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JOURNAL 


OF 


NATURAL  PHIIOSOPHY,  CHEMISTRY, 

AND  THE  ARTS. 


f  : 


'■  H. 


.■?■"* 


*-'  ^ 


> 


JOURNAL 


OF 


NATURAL  PHILOSOPHY,   CHEMISTRY, 


>v  ^  ^F-it  -m'-  ^  *. 


"*■*  •    ■       .  ■■»   K  i^"^   ^^*       -'  ^   ■ 


AND  THE  ARTS 


% 


ILLUSTRATED    WITH    ENGRAVINGS. 


BY  WILLIAM  NICHOLSON. 


VOL.   m. 


LONDON: 

MINTED  rOR  TBX  AUTHOR,  BY  W.  STRATFORD,  CROWN-COURT,  TEMPLE-BAR. 

AND  SOLD   BY    G.   C.   AND   J.   ROBINSON,    PATERNOSTER -ROW. 


M.DCCC. 


f 


v^ 


i      . 


....  i 


/ 


^ 

F 


•  •  • 


•    •  > 


■        • 


•  •    • 


.     JOURNAL 


OF 


NATURAL  PHILOSOPHY,   CHEMISTRY, 


^ 


AND 


THE  ARTS. 


APRIL  1799. 


I  1. 1  i 


ARTICLE  I. 
ARaf^oA  tnfuirj  into  the  Source  of  Nutritku  in  Swcuhnt  VegetaUes^  Sif  M^  J'  GouCH.* 

Kendall,  Ftb.  7^  1799. 


s- 


►UCCULENT  plants  arc  commonly  fuppofed  to  derive  a  greater  proportion  of  nutriment 
from  the  atmofphere^  than  vegetables  of  a  lefs  humid  conftitution  \  and  this  idea  b  fupported, 
at  leaft  in  appearance,  by  a  fingularity  in  the  economy  of  the  plants  under  confidcration.    If 
the  fempervivum  tedorum,  or  any  of  our  indigenous  fedums^be  fufpended  in  the  dry  air  of 
a,chamber»  they  will  live  for  a  long  time  ;  whereas,  other  vegetables  wither  foon  after  their 
connexion  with  the  ground  is  interrupted.    Many  perfonS)  attending  to  the  preceding  fa^b, 
and  reafonbg  from  analogjs  have  concluded,  that  fempervivum  and  fedum,  with  the  reft  of 
the  fucculent  tribe,  derive  this  fupply  not  from  the  earth  but  from  the  atmofphere,  becaufe 
they  can  fubfift  independent  of  the  former :  but  natural  hiftory  points  out  a  fecond  analogy, 
which,  although  it  is  found  in  the  animal  kingdom,  fhould  not  be  overlookecl,  on  account  of 
Its  ftriA  coincidence  with  the  foregoing  deviation  from  the  prevailing  habits  of  the  inferior 
*  d^ds  of  organized  bodies.    The  chameleon  bears  hunger  for  months  together,  when  in  ccm- 
finement :  this  peculiarity,  added  to  the  difficulty  of  obferving  it  take  its  prey,  perfuaded 
the  ancients  that  the  reptile  in  queftion  is  nooriQied  by  the  air  alone,  but  the  induftry 
of  later  naturaliftsf,  has   (hewn  this  notion  co  be  falfc,  by  proving  it  to  feed  on  flies; 
and  that  the  fame  powers  of  abftinence  arc  extended  to  ferpents,  fpiders,  and  many  more 


CommumoKcd  by  the  author. 


Vol.  I U.— April  i799» 


f  Vide  Rail  Synop.  animalium  Quadrup. 

B  animal9|^ 


2  On  the  Source  ofiftirSM  inftucuUnt  W^ttahles. 

animals,  wh6fe  opportunities  to  pr|Aire  {(>oamc  mdarious.  Kow  as  fucculent  plants  are 
intended  to  grow  on  rocks,  and  in  oCbi^drjr  fimations,  wl}«li^t)reir  fupplies  ef  humidity  fufFer 
frequent  and  long  interruptions,  in  al)  firoI^fUHty  ^ey  H^  die  fame  relation  to  the  vegetable 
tribes,  which  reptiles  bear  to  other  animated  befngs. 

The  queftion  whether  of  the  two  opinions  now  dated  is  true,  will  be  beft  refolvcd  by  a  fet 
ef  ftatical  experiments^  made  with  fucculent  plants  furrounded  by  dry  air.  Should  they  ap* 
pear  to  gain  weight  when  treated  in  this  manner,  the  former  notion  muft  be  adopted ;  but 
fhould  they  happen  to  lofe  part  of  their  fubftance,  the  latter  will  have  the  preference :  for  the 
a£l  of  vegetating  implies  the  growth  of  parts  already  formed,  and  the  production  of  new  or- 
gans to  complete  the  plant.  The  following  experiments  were  made,  in  order  to  decide  the 
queftion  under  confideration  i  which  I  {ball  now  relate  without  further  apology. 

Experiment  i^.  Three  plants  of  fedumacre,  weighing  69^  grains,  were  fufpended  in  « 
proper  manner  before  a  window,  on  the  6th  of  September,  1790:  being  again  examined  on 
the  25th  of  the  fame  month,  their  weight  was  reduced  to  42  grains.  They  were  then  placed 
in  water  for  24  hours,  and  afterwards  .expofed  to  the  Ught  and  air  for  half  that  period,  to  give 
the  water  adhering  to  the  plants  an  opportunity  to  evaporate.  At  the  end  of  this  time,  their 
weight  was  63I  grains;  which  is  6^  grains  leis  than  their  original  weight.  Perhaps  the  pre- 
ceding deficiency  is  owing  in  part  to  the  plants  not  being  weighed  before  part  of  their  fap  was 
loft  together  with  the  fuperfluous  water;  but  the  following  circumftance  fhould  alfo  be  taken 
into  the  account.  If  a  glafs  of  limewater  be  placed  under  a  glafs  jar  containing  a  plant  of 
fedum,  the  lime  will  be  precipitated  in  the  courfe  of  three  or  four  days;  from  which  we  may 
conclude  with  reafon»  Aa*  part  of  the  carbon  of  the  plant  is  converred,  m  all  fimilar  cafes,  into 
gas  by  the  oxygen  of  the  atmofphere.  The  lame  experiment  being  repeated  with  fedum  re^ 
flexum,  as  well  as  fedum  acre,  a  confiderable  lofs  of  weight  took  place  in  both  trials ;  and  I 
think  die  tendency  and  uniformity  of  the  refult  will  juftify  the  fucceeding  remarks  and  con* 

clufions. 

'  The  fedum  acre,  in  all  probability,  draws  no  more  nutriment  frpm  die  air  dian  otHer  plants  ;^^ 
at  the  lame  time,  the  herb  in  queftion,  as  well  as  the  reft  of  the  fucculent  tribe,  can  evidently 
retain  life  for  an  unufual  length  of  time,  in  fituations  incapable  of  affording  them  nutrition  in 
the  common  way.  The  vegetative  principle  even  continues  to  a£t  in  the  fedum,  ^en  fuf- 
pended by  the  roots,  apparendy  with  a  view  to  its  prefervation;  for  die  branches  of  the  plants 
ufed  for  the  experiment  curled,  by  turning  their  tips,  contrary  to  die  general  habit  of  vegeubles, 
from  the  window :  by  diis  provident  fingularity,  much  Hght  was  avoided,  an  J  with  it  an  un- 
neceflary  expenditure  of  fap.  The  roots  in  the  mean  time  prodiiced  a  number  of  fine  fila- 
ments, as  if  in  fi»rch  of  humidity;  for  they  feemed,  in  diis  infhuice,  to  imitate  trees  growing 
on  oM  buildings,  which  have  been  known  to  conned  themfetves  with  the  ground,  by  means 
of  roots  defcending  along  die  fides  of  the  waUs*  This  peculiarity  in  the  conftitutions  of  the 
fedums  is  abfolutely  necef&ry  to  their  exiftence ;  for  the(e  plants  being  intended  to  grow  upon 
rocks  and  walls  but  ftightly  covered  with  earthsi  would  be  burned  up  and  deftroyed  by  the 
droughts  of  fummer,  but  dieir  many  fucculent  leaves  obviate  the  diCifter,  by  performing  the 

*  The  fubftancc  of  this  cspcriinent  is  iaferted  in  Wither.  Bot.  Arraogemeat,  edit,  sdv    Vide  arh  Scdum. 


On  thi  Swrci  9f  NuirltiiH  infmuhnt  t^^gitahlis.  ^ 

ijfRcc  of  fo  many  receptacles  of  lap  fufficient  to  anfwer  the  demands  of  thefc  trying  Wfens  i 
and  which  are  recruited  in  a  greater  or  Icfs  degree  by  every  (bower.     Thefe  magazinui  of 
food  are  emptied  in  the  flowering  feafon,  probably  to  feed  the  expanding  capfules ;  for  by  fie 
time  the  feeds  are  ripe,  the  plants  are  exhaufted,  and  fufTer  what  may  be  called  a  vegetable^ 
death,  by  z  natural  procefs. 

Experiment  2.  The  fempervivum  teftorum,  which  rcfcmbles  the  fedums  in  habit,  alfo 
agrees  with  them  in  the  property  in  queftion :  for  an  offset  of  fempervivum,  of  the  weight  of 
250  grains,  being  left  in  a  window  from  the  29th  of  April  to  the  third  of  June,  loft  116 
grains,  and  appeared  to  be  in  a  very  exhaufted  condition,  but  its  Acuity  to  vegetate  remained 
unimpaired  \  for  the  fame  offset  was  afterwards  placed  for  an  hour  every  other  day  in  a  gla(s 
of  rain-water  to  the  end  of  the  month,  by  which  it  was  fo  much  recruited,  as  to  produce  a 
new  (hoot,  and  the  joint  weight  of  parent  and  offspring  amounted  to  170  grains.  Notwith- 
ftanding  the  conclufive  refult  of  the  two  laft  experiments,  it  may,  perhaps,  be  alleged,  that 
the  dry  air  of  a  chamber  does  not  give  fucculent  plants  that  opportunity  to  procure  water  which 
die  atmofphere  affords  them  during  fair  weather,  cfpecially  in  the  nights,  when  the  dews  are 
formed :  but  this  objeAion  feems  to  be  overturned  by  the  fucceeding  paragraph* 

Experiment  3-  I  fufpended  different  offsets  of  fempervivum  tedorum  in  gla(s-bells,  having 
their  mouths  placed  in  water;  which  did  not  rife  in  the  veffels  far  enough  to  touch  the  plant* 
The  air  which  furrounded  the  offsets  was  kept  fo  moift  by  this  fort  of  confinement  that  the  in- 
fides  of  the  jars  appeared  conftantly  covered  with  vapour :  at  the  fame  time  care  was  taken 
not  to  •xpoie  the  apparatus  to  the  dire£t  rays  of  the  fuit.  A  phmt  Seated  in  this  manner  in 
June,  loft  a  (ixth  part  of  its  weight  in  a  fortnight.  Another  plant,  fubje£led  to  a  (hnilar  trial 
during  the  two  laft  weeks  of  September,  loft  but -rr  P^rt  of  its  weight  The  I0&  of  fub(bnce 
which  is  here  remarked,  will  be  beft  explained  by  the  following  fa&>— Dew  does  not  form 
with  equal  facility  on  all  kinds  of  bodies ;  efpecially  in  a  temperature  of  50%  or  higher :  for 
inftance,  glafs  coUedls  dew  from  air,  which  is  not  in  a' (late  to  impart  the  fame  to  vami(hed 
wood  or  polifhed  metals ;  and  were  we  to  form  a  (cale  of  die(e  affinities  by  experiment,  green 
vegetables  would  take  their  refpe^ve  (btiohs,  fomewhere  between  glafs  and  fome  one  of  the 
metals ;  becaufe,  when  the  three  fubftances  in  queftion  are  expofed  to  the  open  air,  glafs  is 
covered  with  dew  in  the  firft  place ;  and  the  vapour  iixes  on  clean  metallic  furfaces,  after  the 
leaves  of  living  (hrubs.  On  this  account,  the  water  contained  by  the  air  u(ed  in  the  laft  ex- 
periment^ attached  itfelf  to  the  fides  of  the  jars,  in  preference  to  the  oflfsets  of  fempervivum; 
which  being  deprived  of  dew,  could  not  repair  die  lofs  they  fuffered  by  evaporation  for  want 
of  aqueods  particles  in  a  condenfed  form*  The  uniform  refult  of  the  preceding  experiments 
feems  to  prove,  beyond  a  poffibility  of  doubt,  that  the  fucculent  vegetables  of  Europe  receive 
riieir  portion  of  nutrition  by  the  common  vehicle  of  water  conveyed  to  them  in  the  common 
way  by  the  earth,  or  depofited  on  their  leaves  in  the  form  of  rain;  and  I  have  reafon  to  fup- 
pofe  that  plants  of  the  fame  defcription,  natives  of  tropical  countries,  are  regulated  by  the  (kme 
principle  of  economy;  for  a  plant  of  aloe  perfoliata,  which  was  fufpended  for  52  days,  about 
die  conclufion  of  autumn,  in  a  room  with  a  northern  afpeA,  loft  fomething  more  than  one- 
fourth  of  its  weight  in  this  dry  fituation;  but  no  attempts  were  made  to  repair  the  lofs  by  the 
meAtds  purfued  in  the  firft  experiment 

B  2  Difiiriptim 


W:\ 


PHkt  SkOriMl  Matkim. 


II. 


J)tfcrtptien  of  a  FotkU  Jti^iand-maeiiiUi  fir  eharpng  a  Jmall  netted  Phial  v/kh  EkBrktif, 

By  J.  Till.  Ulloustone. 


F 


IG*  I  ajid  a,PI.  I,arercprerentation$  of  this  inftrumentof  itsreal  fize ;  ABCD^fijg.  i  and 
2,  are  two  flat  mahogany  boardSf  each  three  inches  Iong»  two  inches  broad,  and  three-eighths 
of  an  inch  thick*    In  the  holes  £  and  F,  fig.  2,  which  are  two  inches  from  each  other,  and 
equtdidant  from  the  fides  and  <ends  of  the  boards,  are  glued  faft  two  cyHndrical  pins  of  box* 
woodt  each  one-fourth  of  an  inch  in  diameter  s  thciepins  |pyroje£l  about  one  inch  and  a  quarter^ 
perpendicularly,  from  the  oppofite  furface  of  the  board,  and  have  their  ends  formed  into  male; 
icrews  about  one-half  of  an  inch  long.    Two  cylindrical  wooden  pins  of  one-eighth  of  an 
Uich  in  diameter^  but  without  icrews,  are  fixed  at  each  end  of  the  fame  boards  and  in  the  (ame 
tranfverfe  lines  with  the  other  pins,  but  near  the  fides,  as  at  G  H  I  J.    They  ftand  parallel 
to  the  other  pins  on  the  (ame  furfiuce  of  the  board,,  and  are  about  a  quarter  of  an  inch  fhorter* 
Ttitfte  pins  pals  through  fix  holes  in/the  board,  fig  i,  when  both  boards  are  applied  together. 
Two  flat  nuts  of  boxwood,  K  and  h,  fig.  i,  of  five-eighths,  of  an  inch  in  diameter  each,  are 
fcrewed  ujpon  the  middle  pins  to  preis  the  boards  together^    Each  board  has  one  of  its  fiices 
covered  with  a  cufliioni  coafifting  of  fix  or  eight  pieces  of  flannel  flightly  ftitched  together^ 
with  perforations  for jhe.i>MM  topalS  iBroiiglu  "  Ihe  cuffiTons  are  covered  WltlT'ikaiQle->fkia 
laid  with  the  fur  outwards,  and  ^  hair  of  ^ck  inclining  to  the  edges  of  the  boards^  in  the  di* 
redioQ  of  the  arrow  in  fig.  i ;  hoks  being  aUo  made  ibrougjb  ^  fluns  tp  admit  the  pins. 
When  the  boards  arc  fcrewed  pretty  dote  together  by  means  of  the  nuts,  with  the  cufliions 
between  diem,  the  redundant  edge  or  border  of  each  flun  is  glued  to  the  edge  of  its  refpedive 
t)oard,  and  they  thus  com(detely  form  two  elaftic  cufluons.    A  piece  of  bra&  wire,  about  one 
tenth  of  an  inch  in  diameter,  is  bent  into  t|ie  bam  M  N  O,  fig.  a,  and  fixed  upon  the  inner 
fide  of  this  board,  which  is  fiiced  with  die  fiir^  Ind  in  the  fituation  reprefented  in  the  drawings 
by  means  of  two  (crews  which  pals  through  pieces  of  flat  bra&,  fbUered  on  the  wire.    To 
the  parts.M  SOT  of  dib  wire,  a  tin  tube  isfoldered,  open  at  both  ends,  and  fitted  to  re- 
ceive the  lower  part  of  a  very  thin  ounce  or  ounce  and  half  phial  or  jar,  coated  on  both,  fides 
with,  tinfoil,  excepting  i|  of  an  inch  of  its  top.    This  phial^  when  placed  firm  in  the  tin  tube, 
has  its  wire  parallel  to,  and  14  inch  fi'om,  the  fide  of  one  of  the  boards,  and  like  wife  in  the 
£une  plane  with  that  produced  by  the  contad  of  the  two  cufliions.    The  wire  proceeding 
from  the  infide  coating  of  the  phial  is  fixed  firmly  in  its  nedb,  by  means  of  a  narrow  filk  rib* 
band  dipped  in  melted  eleflric  cement,  and  rolled  lighdy  round  the  (ame  wire  to  a  proper  degree 
of  thicknefi.    The  fpace  U  V  X  W,  fig.  x,  is  without  tin,and  is  radier  more  dianhalf  the 
circumference  of  the  tube.    Thus  die  charged  phial  may  be  removed  from  the  machine, 
widiout  the  hazard  of  difcharging,  by  pufliing  it  fiarward  a  little  with  the  thumb  applied 
againft  its  bottom,  and  then  taking  hold  of  it  by  its  coating.    R  is  a  curved  wire,  widi  a 
ball  to  it,  which  by  moving  on  E  as  a  Gentre,and  ftanding  at  any  angle, it  is  raifed  to  anfwer 
die  end  of  an  eledrometer  and  difeharger  of  the  phial.    The  figure  <rf'  an  arrow  is  made  00 

tho 


Pockit  Machint  fir  t barging  tm  EUffrical  Jar.  5 

the  board,  fig.  i,  widi  its  point  in  the  fame  diredton  to  which  the  fur  of  its  cufhion  ii^lincs, 
in  order  to  fhew  the  proper  application  which  is  alfb  fecured  by  the  pins.  The  ends  of  a 
filk  ribband,  two  inches  broad,  and  a  yard  or  32  inches  long,  are  neatly  fewed  together  vrit^, 
fiik,and  the  ribband  afterwards  fteeped  in  weak  feed-lac  vamifli.  Indofe  the  ribband  betwixt 
the  cufbions,  the  arrow  pointing  towards  the  wire  of  the  jar.  The  machine  being  expofcd 
to  the  moderate  warmth  of  a  fire  for  ten  or  twelve  minutes,  efpecially  in  damp  weather, 
and  the  cufliions  made  to  prefs  gently  againft  the  ribband,  fet  the  balls  a  quarter  of  an 
inch  from  each  other,  then  hold  the  inftrument  by  the  boards  in  the  left  hand,  and  with 
the  right  hand,  at  a  pretty  good  diftance  from  the  wire  In  the  phial,  draw  the  ribband 
gently,  keeping  the  filk  under  the  wire  of  the  jar,  and  in  qontafl  with  it.  At  fix  revolutions' 
of  the  ribband,  the  phial  will  generally  difcharge  it(elf  at  the  above-mentioned  diftance  of  the 
balls.  Twelve  revolutions  of  the  ribband,  when  the  excitation  Is  powerful,  and  the  balls  fe- 
parated  at  a  confiderable  diftance,  will  produce  a  charge  of  the  jar,  which  few  perfons  would 
choofe  to  receive  a  fecond  time.  Mole-flcin,  with  the  hair  on,  excites  filk,  or  the  refinous  plate 
of  an  ele&rophorus,  better  than  the  fur  of  any  indigenous  animal  the  writer  of  this  has  tried: 
this  he  difcovered  by  accident.  The  machine  may  be  carried  conveniently  in  the  pocket  in 
an  oval  cafe  nude  of  pafl:eboard» 

This  inftrument  is  not  to  be  confidered  (blely  as  a  philofophical  plaything ;  it  may  be  ufed 
when  a  common  eledrical  machine  is  not  at  hand,  as  an  auxiliary  in  recovering  peffons  appa* 
rently  dead  by  drowning,  and  other  kinds  of  fuffbcation;  and  when  the  unfortunate  obje^ 
are  at  fomc  <liftance,  it  will  be  found  not  a  little  convenient,  on  account  af  its  portable  fize. 
It  may  likewife  be  very  advantageoufly  applied  in  (otac  cafes  crf'menftnial  obftrudion,  and  in 
feveral  morbid  aiFedions  where  fmall  fliocks  are  indicated.  In  fu^nded  animation  from  fub- 
oierfion,  (bocks  of  a  proper  degree  of  ftrejagth  nuy  .be  given  conveniently  by  this  inftrument 
in  the  following  manner,  paffing  each  charge  through  the  breaft,  at  the  moment  the  lungs  ar(^ 
expanded  by  an  affiftant.  Apfdy  the  knob  of  the  charged  phial,  held  by  its  coating  in  one 
hand  to  the  region  of  the  heart  of  the  patie^ty  at  the  feme  time  that  a  finger  of  the  other  hand 
is  in  contaft  with  the  ipine.  To  avoid  the  (hock  which  the  operator  receives  in  this  cafe, 
the  eledlrical  circuit  may  be  completed  by  means  of  a  portable  conduAor  formed  of  a  gold, 
fflver,  oc  copper  thread,  neatly  indofed  in  a  filk  ribband^  except  its  ends.  When  the  phial 
is  about  to  be  difidbarged,  perhaps  it  may  be  right  not  to  fuffer  any  part  of  the  patient's  body 
to  come  in  contaA  with  this  conductor,  but  the  (pine;  and  this  may  be  cffe^d  by  means  of  an 
affiftanty  and  one  hand  of  die  operator* 


III. 
On  the  Corundunhjlme  frem  Afia.    By  the  Right  Homurablt  Chamles  GAEFJLLMf  F.R.S. 

(Concluded  from  page  544,  toL  II.) 


Wi 


£  frequently  fee  fmall  rhombs  traced  on  the  furface  of  the  planes,  on  the  ends  of  the 
hexaedral  prifin,  fig.  10,  PI.  XXIV,  vol.  II.  This,  no  doubt>  is  occafionedLalfo  by  the  inter- 
fediQn  of  the  lamine,  on  the  planes  of  the  primitive  rhomboidal  parallclopiped.    But  thefe 

rhombs. 


'11 


6  0»  tie  erjflMnt  Forms  ef 

rhomVSf  formed  by  the  reunion  of  lines  that  join  in  angles  of  6o^and  I20*,  inftead  of  86^  and 
94^  (like  thofe  we  have  ft-en  traced  on  the  faces  which  correfpond  with  thofe  of  the  rhomboidal 
/arallelopiped),  form  angles  of  6o^  and  120^.  It  would,  therefore,  be  an  error  to  confider  them 
as  indications  of  the  form  of  the  elements  of  cryftallization,  as  we  are  tempted  to  do  fi-om  a 
iimple  infpedtion  of  the  cryftal.  Thefe  (ame  lines  form  equilateral  triangles  with  one  another, 
ai  may  be  feen  in  fig.  10. 

The  caufe  of  thefe  fmall  equilateral  triangles,  which  (bmetimes  projeA  a  little  over  the 
planes  on  the  end  of  the  prifm,  mud  now  be  obvious.  If,  during  the  fuperpofition  of  the  cry- 
fialline  laminae  on  all  the  planes  of  the  rhomboidal  prallelopiped,  it  has  happened  from  any 
caufe  whatever,  that  the  laminae  depofited  on  the  three  &ces  of  the  (ame  fumipit,  have  not 
fallen  exadlly  on  thofe  which  preceded  them,  or  that  they  have  experienced  fome  deviation,  or 
have  not  had  the  fame  decreafe,  as  all  the  others,  at  the  angle  of  86%  thefe  triangles  muft  ne* 
ce/Tarlly  occur;  in  the  (ame  manner  it  muft  be  obvious,  why  thefe  fmall  equilateral  triangular 
projections  are  frequently  placed  on  one  of  the  fides  of  the  cryftaL 

The  primitive  form  of  the  corundum  cryftal  is  therefore  a  rhomb<Mdal  parallelopiped,  who(e 
folid  angle  at  the  fummit  is  84^  jiS  and  that  formed  by  the  reunion  of  the  bafes  is  95^  %K)\ 

The  cryftalline  laminae  are  rhombs  of  86*^  and  94® ;  thefe,  in  my  opinion,  are  double  cry- 
ftalline  molecules;  the  fingle  molecules  I  apprehend  to  be  ifofceles  triangles,  of  86^  at  the 
angle  of  the  fummit,  and  of  47^  at  thofe  of  the  bafe*. 

Although  the  rhomboidal  paralW^w^  oL%£i9  and  £^  k  the  i^rimitive  form  of  Ac  corun- 
dum cryftal,  yet  it  is  rare  to  meet  with  that  fubftance  under  this  perfeft  and  determined  form  ; 
and  in  moft  mineral  fubftances,  it  is  more  rare  to  meet  with  their  primitive  cryftals,  than  their 
different  modifications.  Amongft  Mr.  'Greville's  numerous  fpecimens  of  corundum,  I  have 
met  with  only  one  which  has  this  primitive  form,  and  it  is  doubtful  whether  even  this  may 
not  be  a  fragment 

The  corundum  cry(hil  prefents  another  modification,  imder  which  the  regular  hexaedral 
prifm,  inftead  of  having  three  alternate  folid  angles,  at  each  of  its  ends  (on  which  folid  angles 
are  placed  ifofceles  triangular  planes,  forming  a  folid  angle  of  122^  34'  with  the  planes  at  the 
extremities  upon  which  they  are  inclined),  has  alfo  its  angles  fupplied  by  ifofceles  triangular 
planes;  but  thefe  planes,  inftead  of  122?  34',  form  folid  angles  of  160^  42,^  with  the  faid 
planes  on  the  extremities.  (See  fig.  1 1  and  12.)  Thefe  new  planes,  which  conftitute  a  new 
modification  of  the  primitive  form  of  corundum,  are  the  refult  of  a  different  order,  in  the 
decreafe  of  the  laminae ;  which,  in  the  primitive  form,  are'  depofited  on  the  planes  of  its  pri- 
mitive rhomboid  by  ftngle  rows  of  cry(blline  molecules,  and  increafe  the  planes  which  ter- 

"*  I  am  at  prefent  preparing  a  work,  in  which  I  (hall,  if  circumftances  pennit  me  to  finiOi  it,  give  the  refult 
of  my  obfervatioas,  and  my  own  opinion  on  this  intereiling  part  of  mineralogy.  I  ihall  only  obferve  here, 
that  although  double  molecules,  fquare  and  rhomboidal,  are  frequently  formed  in  the  procefs  of  cryftalliza- 
tioD,  yet  the  real  JForm  of  the  cryftalline  molecules  feems  to  be  triangular.  By  obfcrving  the  pregrefs  of  the 
rhomboidal  parallelepiped,  ia  its  paflage  to  the  form  of  an  hexaedral  prifm  (fig  4  and  5),  and  by  confidering 
the  prifm  terminated,  it  feems  evident,  that  the  laft  laminae  which  had  been  depofited,  after  the  progreffive 
decreafe  in  the  rows  of  crydallinc  molecules  to  one  fioglc  molecule,  muft  neceflarily  have  been  triangular.    B. 

minate 


^    the  C^runiwnrfimi  fi%m  Afiok  ff 

iDinate  th6  hexaeditm :  whereas,  in  diis  fecond  modification,  the  decreafe  of  molecules  is  bj  two 
rows,  which  gives  a  more  obtuTe  inclination,  and  forms  new  planes^  The  fur&ce  is  ufualljr 
ftriated,  parallel  to  the  (Ides  of  the  planes  which  terminate  this  cryftal ;  an  appearance  always 
announcing  imperfedion  in  the  cryfiallization,  arifing  either  from  a  change  in  the  ordet  of 
decreafe  or  increafe,  or  from  a  lefs  perfed^  union  of  the  cryftalline  laminae.  A  fe<^ion  would 
fliew  gradual  rifings  or  fteps,  as  appears  in  fig.  14,  which  is  a  fe£lion  of  fig.  13,  in  the  line 
A  D  B.  Thefe  ftriae  are  not  to  be  confounded  with  thofe  in  numberlefe  fubftances,  as  ia 
tourmalines,  fchorl;:,  &c.  which  arife  from  the  longitudinal  union  of  numberlefs  diftinA  cry* 
ftals.  The  cryftal  refulting  from  this  new  mode  of  decreafe  in  the  cryftalline  hminse,  will 
reprefent  one  or  other  of  the  varieties  (hewn  in  fig.  11,  12,  and  13,  according  to  the  period 
when  fuch  decreafe  has  begun  in  the  procefs  of  the  cryftallization ;  and,  if  it  has  begun  very 
{ate,  the  new  faces  will  only  be  fmall,  nay,  almoft  imperceptible,  ifofeeles  triangles,  forming 
folid  angles  of  160^  42'  with  the  planes  of  the  extremities  of  the  prifm,  as  in  fig.  5 ;  the  mea-» 
fure  of  the  angles  however  muft  be  excepted. 

If  this  irregular  mode  of  decreafe  had  begun  with  the  firft  cryftalline  laminar,  which  were 
•depofited  on  the  primitive  rhombddal  parallelopiped,  the  hexaedral  prifin  refulting  therefrom 
would  have  been  terminated  by  two.  very  obtufe  triedral  pyramids,  whofe  planes  would  have 
been  rhombs  ;  and  they  would  have  been  placed  in  a  contrary  direction  to  each  other,  as  ma/ 
be  feen  in  fig.  I2)  by  the  dotted  lines.  I  have  not  met  with  this  variety,  but  its  exiftence  may 
be  fuppofed. 

It  happens  ibmetimes,  that  the  cryftallization  has  not  been  fo  perfe£l  as  to  deftroy  every 
appearance  of  ^kt  faces  of  the  primitive  rhomboidal  paraIielopipc«l  ^  In  diis  cafe  there  remainS) 
on  the  folid  angle  of  iia^^,  fi^rmed  by  the  junction  of  the  new  bets  with  the  edges  of  the 
prifm,  a  fmall  ifofceles  triangle,  as  in  fig^  1 3,  whidi  correfponds  to  thofe  in  fig.  5,  of  die  pre- 
ceding modification. 

The  cryftals  which  explained  the  fecond  modification,  form  alfo  a  part  of  Mr.  Greville's 
col]e£^ion :  one  in  particular,  is  highly  worthy  of  notice;  it  is  the  moft  perfed  cryftal  I  have 
ever  feen  of  this  fuMance.  The  furiace  of  the  fiioes  of  the  prifm,  although  rough,  is  in- 
finitely lefs  fo  than  that  of  the  others,  and  much  more  brilliant.  The  planes  on  the  ends 
have  the  ufual  polifti  of  cryftak;  its  colour  is  a  pale  red,  and  its  tranfparency  may  be  com- 
pared to  that  of  wax. 

This  fubftance  prefents  a  third  modification,  in  which  the  hexaedral  prifm  diminiflies  in 
diameter,, as  is  apparent  by  comparing  the  diameter  of  its  two  ends ;  in  ibme^  it  appears  like  a 
regular  hexaedral  pyramid  truncated  (fig.  15).  The  cryftals  of  this  modification  are  ufually 
irregular,  and  feMom  admit  of  a  certain  meafure  of  their  angles  i  but  among  the  numerous 
Q)ecimehs,  in  Mr.  Greville's  colledion,  I  have  been  able  to  afcertain,  in  the  greater  part, 
that  the  hexagonal  plane  at  the  top,  forms  angles  of  about  lao^',  with  the  planes  of  the  py- 
ramid ;  and  the  hexagonal  plane  at  the  bafe,  forms  angles  of  about  78^^  with  the  planes  of  the 
pyramid.  In  other  inftances,  the  form  of  the  pyramid  varies  greatly ;  in  fome  the  angle  at 
the  upper  plane  was  i  lo^',  and  the  angle  at  the  bafe  about  70^ ;  in  others^  the  angle  at  the 
upper  plane  was  about  ioo^>  and  flie  one  at  the  lower  plane  about  So?. 

In 


/ 


9  Onihi  cryJlalKm  Fmm  of  Ctrtuulum. 

.    In  thefe  (krd  varieties,  the  cryftalline  laminae  can  be  feparated,  as  in  the  hexagortal  prifmii 

at  the  three  folid  alternate  angles  of  each  end,  but  in  a  contrary  dire&ion  to  each  other.     The 

planes  which  appear  when  the  laminae  are  detached  regularly,  form  (olid  angles  of  22^  54.' 

'  /  with  the  planes  of  the  extremity :  this  arrangement  is  analogous  to  that  of  the  hexaedral  prifia . 

/  The  difference  of  form  arifes  from  the  cryftalline  laminae  depofited  on  the  planes  of  the  pri<p> 

/'  tnitive  rhomboid,  decreafing  by  more  than  one  row  of  molecules,  on  the  planes  of  one  of  the 

triedral, pyramids  of  the  rhomboid,  and  by  left  than  one  row,  on  the  planes  of  its  other  pyra« 
mid.  This  general  obfervation,  on  the  manner  in  which  diis  primitive  cryftal  of  corundum 
paiTes  to  the  different  varieties  juft  mentioned^  is  the  only  one  I  have  eftablifhed  with  any  de« 
gree  of  certainty  at  preient.  Specimens  with  perfed  cryftals,  whoTe  angles  may  be  meafured 
with  accuracy,  will  probably  arrive  from  India,  and  give  further  demonftration,  as  to  thefe  and 
other  varieties  of  modificatians  of  corundum.  We  may  conceive,  that  if  in  this  modificadoii 
the  cryftaHization  had  ceafed  before  the  intire  formation  of  the  cryftal,  there  would  have 
remained  fmall  ifofceles  triangular  planes,  on  three  of  the  alternate  folid  angles,  formed  by  th^ 
jundion  of  the  planes  on  the  ends,  with  the  edges  of  die  truncated  pjrramid*  Thefe  ifofceles 
triangular  planes  refemble  thofe  we  have  feen  in  the  firft  modification  (fig»  4  and  5),  and  form» 
in  the  fame  manner,  folid  angles  of  122^  34/  with  the  planes  on  the  ends  of  the  prifm 
(fig.  16.) 

Finally,  if  during  the  formation  of  die  cryftal,  in  this  mpdificadon,  it  (hould  happen  that  the 
laminae  depofited  on  the  three  planes  of  the  rhomboidal  parallelopiped,  on  the  fide  where  they 
undergo  a  greater  decreafe,  do  not  undergo  th»  decreafe  of  one  row  of  molecules  at  the  acute 
angle  of  the  fummit»-<h«^cryftal  w31  be^a  r^  hexaedral  pyramid  (fig.  17);;  who(a  acute  angle 
at  the  fummit,  meafured  on  the  fides,  will  be  neariy  24%  in  ooe  of  the  varieties;  40^  for  the 
moft  obtufe;  and  20^  for  the  m^ft  acute  variety :  the  angle  of  their  triangular  planes,  in  the 
firft  inftance,  I3'^4i'»  in  the  fecond,  22°  20';  and  11°  28' in  the  third.  I  have  not  (Srca 
anyperfed  pyramids;  but  in  many. die  hexagonal  pbuie  terminatihg  the  pyramid  is  fo  finally 
that  it  renders  its  total  fiippreiBon  probahk. 

This  decreafe  necef&rily  produces  a  fingle  pyramid,  as  above  mentioned ;  neverthelefs,  there 
are  inflances  of  cryftals  of  corundum^  belonging  to  the  variety  where  the  terminal  planes 
inake,  with  the  planes  of  the  pyramid,  a  fiibd  angle  of  about  100%  in  which  two  pjrramids  of 
the  fame  dimenfions,  having  their  fummit  replaced  by  a  fmall  hexagonal  plane,  are  placed  bafip 
to  bale.  - 

I  have  alfo  obferved  among  the  cryftals  of  the  cbCuie  variety  above  nsentioned,  in  Mr.  Gre- 
Vilie's  colledion,  an  inftance  of  the  decrsale  taking  plaoe  by  feveraf  rows,  on  ooe  three-Qded 
pyramid  of  the  primitive  rhomboid,  and  by  fingle  rows  on  the  other.  Confequently,  thie 
cryftal  is  a  fliort  itegvtar  hexaedral  prifin,  terminating  on  ooe  end  only  by  an  hexaedral  pyrar 
mid  ;  the  planes  of  which,  as  well  as  of  tke  prifia,  are  alternately  broad  and  narrow,  and  s^moft 
perfed,  its  apex  being  replaced  by  a  very  fmail  plane. 

I  (hall  conclude,  by  mentioning  a  varietjrof  coruodumt'defia-ibed  by  the  Abbe  Hauy»  in  the 
JiHjFnal  iH  t\Unesi|  No.  ^8;  in  which  the  edges  ol  the  terminal  plsgives  of  the  hexaedral  prilki 
are  replaced  by  pLincs  which  form  anism^  of  1  l6^  31'  with:tbe  teirmtn^  pjanes  ;  but  in  the 
Aumcrous  collewlion  of  Mr.  Qreville  I  have  not  feen  this  variety.     One  cryftal  had  an'ap- 

pearanco 


.  \ 


On  the  cryjialline  Forms  of  Corundum,  9 

pearance  of  fuch  planes ;  but,  on  examination,  it  was  clearly  accidental.  The  authority  of 
the  Abbe  Hauy  in  cryftallography,  is  fo  great,  that  the  exiftence  of  fuch  modification  ought 
not  to  be  denied  without  further  examination ;  though  I  cannot,  in  this  inftancc,  adopt  it :  he 
derives  this  variety,  which  he  calls  fubpyramidal,  from  a  decreafe  of  three  rows  of  molcculesi 
at  the  angles  of  the  bafe  of  the  two  pyramids  of  the  primitive  rhomboid  j  and  hefecms  to  attribute 
the  fame  formation  to  the  pyramidal  variety  with  double  pyramid,  which  he  fuppofes  may  exi(h 

The  primitive  cryftals,  and  the  iirft  and  fecond  modifications  of  corundum,  are  from  the 
peninfula  of  India.  The  third  modification,  or  the  pyramidal  variety  is  from  China ;  nothing 
approaching  this  form  being  among  the  Specimens  which  Mr.  Greville  received  from  the 
peninfula  of  India. 

The  preceding  oblerivitions,  and  particularly  the  laft-mentioned  modification  of  corundum, 
compared  with  the  beft  defcription  of  the  fapphire,  fuggeft  the  furtho:  examination  of  the  degree 
of  conne£^ion,  if  not  of  identity,  of.thefe  oriental  ilones. 

In  both,  the  hexaedral  pyramids  are  ufually  incomplete  in  their  apex,  and  ^y  vary  in  acute- 
nefs.  I  have  flated  the  degree  in  which  the  foiid  angles  of  the  pyratnid  (taken  as  complete) 
vary,  in  corundum,  to  be  from  20^  to  40®. 

Rome  de  L'Ifle  ftates,  that  the  fapphire  varies  from  20®  to  30*^.  The  Abbe  Hauy  (Journal 
de  Phyfique,  Aug.  1793)  mentions  two  varieties  of  the  fapphire,  one  meafuring  at  the  folid 
angle  of  the  pyramid  40°  (>\  the  other  57^  24'.  I  never  iaw  a  fapphire  with  fo  obtufe  an 
angle  as  the  laiil,  but  many  whole  angle  at  the  top,  if  the  pyramid  had  been  complete,  would 
have  been  the  fame  as  that  of  the  corundum.  Befides  the  analogy  between  the  cryftals  of 
corundum  and  the  fapphire,  by  the  union  of  two  hexaedral  pyramids  at  their  bafe,  it  alfb  exifb 
by  the  ineafure  of  their  angles ;  and  both  fubfbnces  are  fubjei^  to  the  fame  irregularity, 
fometimes  appearing  as  a  fingle  hexaedral  pyramid,  and  fometimes  as  an  hexaedral  prifm : 
moreover,  the  fapphire  fometimes  has  on  its  folid  angles,  alternately,  the  fame  triangular  planes, 
(fig.  5.),  and  alfo  the  prominent  triangles  on  the  planes  of  the  extremities  (fig.  10.),  which 
often  appear  in  the  cryflals  of  corundum.  The  Abbe  Hauy,  in  the  Journal  de  Phyfique, 
Auguft  1793,  names  this  variety,  orientale  enneagone  ^ifhiQYi  is  reprefented  in  the  annexed  plate 
(fig.  1 8*},  and  fays,  that  the  fmall  triangular  planes  make  with  the  terminal  planes  an  angle 
of  122^.  iVf  and,  in  the  defcription  of  the  fame  triangular  planes  in  the  corundum  (fig.  16.), 
it  appears  that  tbefe  planes  are  the  remains  of  the  planes  of  the  primitive  rhomboid,  and  fomf, 
with  the  terminal  planes,  an  angle  of  122^  34^ 

Perhaps  the  rhomboidal  cryflal,  which  Rome  de  L'Ifle  had  given  as  one  of  the  forms  of  the 
fapphire,  fhould  be  reflored  to  it.  He  had  examined  it  at  M.  Jacquemin's,  jeweller  to  the 
crown.  (Cridallographie,  i  edit.  p.  221),  and  he  fupprefTed  it  in  his  fecond  edition,  but  often 
expreffed  to  me  his  regret  in  having  made  the  alteration.  I  have  before  me  a  letter  firom  that 
celebrated  naturalifl,  dated  September,  1784,^  in  which  he  inclofed,  for  my  opinion,  a  copy  of 
a  letter  he  had  received  from  Mr.  Werner,  with  models  of  fome  cryflals ;  among  them 
two  called  by  him  rubies ;  one  a  rhomboid,  of  which  the  angles  of  the  fummit  are  fubflituted 
by  planes  (fig.  19.),  the  other  is  precifely  the  fame  as  fig.  3,  4,  and  5,  of  the  annexed  plate. 

^  A  iener  to  the  fame  effeft  was  written  to  Mr.  la  Mcthcrie,  and  publiflicd  ic  the  Journal  de  Phyfiquc» 
May,  1787. 

Vol.  IIL— April  1799.  C  The 


t9  On  thi  cryJlaUim  Forms  of  Corundum. 

The  foHowing  is  a  trariflatiQn  of  Rome  de  L'Ifle's  words :  <^  The  Arft  of  dieTe  rubies  has 
^  evai^ly  the  fame  form  as  I  have  reprefented  in  plate  IV.  6g.  60,  of  my  Criftallographie, 
^  viz.  a  rhomboidal  parallelopiped,  truncated  at  each  of  its  obtufe  angles,  by  an  equilateral 
<*  triangular  plane." 

**  You  will  have  acorrefi  idea  of  the  tidier  cryftal,  if  you  fuppofe  the  cryftal,  reprefented  in 

^  Plate  IV.  fig.  87,  truncated  at  each  of  the  fummits  of  its  pyramids,  by  an  equilateral  triangu- 

*^  lar  Plane,  as  in  the  preceding  modification,  but  deeper,  and  in  fo  great  a  degree,  that  the 

^  three  rhombic  plants  of  each  pyramid  di&ppear  with  the  exception  of  three  ifofccles  trian* 

'*  gles :  this  modification  differs  from  the  firft  only  by  the  hexaedral  prifm,  and  the  deeper 

•**  truncature  at  the  fiimmits  of  the  pyramids.'* 

It  is  therefore  clear,  that  if  the  primitive  rhomboid  of  corundum  deftreafed  only  at  die  fupe- 
rior  angles  of  its  laminae,  it  would  exhibit  exadlythe  firft  of  thefe  varieties  of  Mr.  Wemcr^s 
ruby,  as  in  the  annexed  fig.  19. 

As  to  the  fecond  variety  of  Mr*  Werner's  ruby,  it  is  equally  dear,  if  in  fig.  87,  referred 
to  by  Rom£  de  L'lfle  (reprefented  by-the  annexed  fig.  20.),  no  more  of  the  pyramid  was  left 
than  the  three  fmall  triangles  by  Oy  r,  there  would  be  precifely  one  of  the  forms  of  corundum 
before  defcribed,  to  which  the  annexed  figure  5  belongs. 

It  may,  perhaps,  be  objeded,  that  the  laminae  appear  to  be  parallel  to  the  terminal  planes, 
in  die  fapphire,  and  inclined  in  the  corundum. .  There  are  crjrflak  of  corundum,  in  which,  very 
frequendy,  the  lamiftiv  appear  parallel  to  the  terminal  planer  I  was  at  firft,  and  for  fome  dme,  de* 
<:cived  by  duit  appearance.  In  other  corundum  cryftals,  the  laminae  appear  to  be  parallel  to  the 
prifmattc  planes ;  and  to  conclude  die  inftances  of  analogy,  the  iliperpofidon  of  rhomboidal 
laminae  is  fomedmes  obfervable  in  oriental  ndiies  and  fapphires.  It  was  by  this  appearance, 
Mr.  Greville  was  led  to  try  the  effeft  rf  cutting  Ae  foreraendoned  ftones  en  cahchon ; 
whereby  a  fimilat  efFed  of  triple  refledioa,  which  formed  ftars  of  fix  rays  from  a  common 
centre^  was  produced  in  the  oriental  ruby,  vk  the -fapphire,  and  in  the  corundMm« 

It  is  to  be  lamented  that  Mr.  Werner  did  not  fend,  with  his  models,  the  fpecific  gravity  of 
each  of  the  rubies,  and  the  meafures  of  their  angles :  we  ffaould  then  have  had  data  to  decide 
wbether  the  rubies,  fent  by  Mr.  Werner,  were,  as  I  fuppofe  them  to  be,  oriental  rubies,  or 
iapfmires ;  and,  with  equal<:ertaint^,  whether  the  paraHelopiped  rhomboid  correfponds  precifely 
with  that  of  the  corundum :  by  this  the  perfeft  identity  or  analogy,  between  die  corundum  and 
the  fapphire,  would  have  been  no  longer  doubtful* 


TMi 


Specific  Gravities  of  preciuet  $t$9teim^ 


itf 


Table  of  the  fpecific  Gravity  of  the  Corundum,  Sapphire^  Topaz,  Rubjy  and  Diamndf  om 

dijferent  authoriAes^ 


Hatchett  and  Greville 

H.  and  G. 

Klaprodi 

Klaproth 

Blumenbach 

Brifibn 

Hatchett  and  Greville 

Lichtenberg 

Grofs 

Hatdiett  and  Greville 

H.  and  G» 

H.  and  G. 
H.  and  G. 
H.  and  G. 
Klaproth 

Briflbn 

Bergman 

Quift 

Bergman 

Klaproth 

Bergman 

Briflbn        -  *      - 

Briflbn 

Blumenbach 

Hatchett  and  Greville 

Werner 

Blumenbach 

Hatchett  and  Greville  . 

Briflbn 

Blumenbach 

Hatchett  and  GieviHe 

MuCchenbroek 

Blumenbadi 

La  Metberie 


Corone.    Bengal 


Corundum* 

2,768  *  Matrix  of  corundum*.    Coaft 
^9785  *  Lump  of  corvndum.    Coaft 

3>07S 
3,710 

3'«73 
3.876  * 
3,90a 

3.935 

3)950  *  Cryftal  of  corundum.    Coaft 

3>954  *  Ditto,  with  vitreous  crofs  fra£lure 

Coaft 

3,959  *  Ruby-coloured.    Coaft 
3,959  *  Chatoyant.     China 
a,9i6a  *  Cryftal.     China 
4*180 

Sapphire 

.  39T30    Brafilian;  probably  a  topas 
3>6S0  t 
3,800  t 

3>940  t 

3'950  t 

3>974  t 

3,9$*i  f  White  oriental 

3»994  + 
3,994  t  Blue 

4>oo0  f  *  Gueyifli  ftar-flionc 

4,000  f 

4>oio  f 

4,0J5  t  Blue  ftar-ftone 

4,076  f  From  Pay-en- Velay 

4,c8j  f  Crimfon 

4,083  t*  Pale  blue  cryftal 

4,090  f 

4,100  t  Ydlov^ 

4,200  . 

,4,200  + 

C2 


"Topaa^ 


12 


Spiitfic  Gravities  ofpreciws  Stoms: 


liTi  Metherie 

Bergman 

Werner 

Quift 

Werner 

Briffon 

Briffon 

Werner 

Briffon 

Werner 

Briffon 

Briffon 

Bergman 

Bergman 

Mufchenbroeck 

Quift 

Blumenbach 

Quill 

Briffon 

Klaproth 

Hatchett  and  Greville 

H.  and  G. 

Blumenbach 

Blumenbach 

Briflbn        -        -     . 

Hatchett  and  Greville 

Quift 

Bergman       »       « 


Topaz. 

29690    Siberia 
3*460 

3*464 
3»Soo 
3iSa» 
3^531 
3>536 

3i54o 
3»548 
33556 
3*564 


Light  blue.    Brazil 


Eibenftocher 

Red.     Brazil 

Dark  yellow.    Brazil 

Dark  yellow.     Brazil 

Oriental 

Schneckenfteiner 

Schneckenfleiner 
4,010  f  Oriental 
4,560 1 

Ruby. 

3,180 
3,180 
3,400     Spinel 

3,4:54     Ccykm 
3,500    Brazil 
3,53 1     Brazil 

3>57o 

3,57 1  ♦  Odoedral  cryftal 

3,625  *  Macle  of  Odloedral  cryftal 

3*645 

3>76o 

3*760 

4,166^  Sahm  Ruby.    Star-ftone.    Coaft 

4,200  f 

4>24ot 

Diamond. 

3*356    Pcriea  cryftal 


Aggregate  cryflal 


Hatchett  and  Greville 

Wallerius  -  .  - 

Hatchett  and  Greville 

Cronftedt        ... 

Mufchenbroeck 

La  Metherie         *         -  « 

Briffon        -  •  .  - 

Werner        -        -         •'        - 

*  .      »  ■  •       • 

The  Mark  *  diftiiij^aUhes  the,  fpeeinens  ui  my  coUettra,  to  wfaichi  I  have  referred  in  ,tbe 

fer^gmns  paper. 

The 


3>4oo 
3.47 » 
3>5oo 

3,600 


'■Kr 


Refearches  into  the  hiatal.  Communication  ef  Motion  in  Fluids.  13 

The  mark:  f  diftinguiflies  the  ^kjies,.  which,  from  their  fpecific  gravity,  I  think  .belong  to 
the  genus  of  corundum.  •  I 

The  generic  name  corundum,  lam  in  the  habit  of  giving  to  thofe  forts  which  havca  fparrt', 
or  a  granulated  frafture.  When  corundum  has  a  vitreous  crofs  frafture,  I  call  it  fapphirc; 
and  diftinguifli  its  varieties  by  their  colours,  white^  red,  blue,  yellow,  green ;  and  by  the  acci- 
dental rcfleftion  of  light  from  their  laminx:  when  in  orte  direftion,  I  call  the  fapphire  cha- 
toyant; when  the  refleftion  is  compounded  of  rays  which  interfeft  each  other,  and  appear  to 
diverge  from  a  common  centre,  I  call. them  ftar-ftones,  as  red,  blue,  or  greyilh  ftar-ftones,  or 
j(jtar  fapphires. 

IV. 

Experimental  Refearches  concerning  the  Principle  of  the  lateral  Communication  of  Motion  in 
Fluids-^  applied  to  the  Explanation  of  various  Hydraulic  Phenomena.  By  Citizen  y.  B.  Ven^ 
irURl^  Profeffor  of  Experimental  Philojophy  at  Modena^  Member  of  the  Italian  Society^  of 

' .  the  Injiitute  of  Bologna^  the  Agrarian  Society  of  Turin^  bfc. 

(Concluded  from  page  494,  voli  II.) 

PROPOSITION  XI. 

« 

If  the  xvctter  of  a  refervoir^  which  flows  through  an  horizontal  aperture^  be  influenced  by 
mny  foreign  motion^  it  will  form  an  hollow  whirl  above  the  orifice  itfelf. 


c 


« •  •   •  • 


*•      A  I  •  •         •     •       •  ••  •      •  •     •       *!.'%-      \ 


•  •••  . 


. .  •   •• 

■•  •     • 


V 


ITIZEN  BoflTut,  has  given  a  very  good defcription  of  this  kind  of  eddy*.  It  is  of  a'£fier- 
ent  nature  from  thofe  confidered  in  the  foregoing  propofition  $  but  the  caufes  of  both  are,  in  fome 
rcfpefts,  fimilar,  for  which  reafon  I  prbpofe  to  attend  to  them  more  particularly  in  this  place. 

Let  D  Q^fig.  18  (plate  XXII,  vd.  II),  reprefent  an  horizontal  plane  near  the  orifice  £  Ft 
through  which  the  fluid  of  the  refervoir  M  N  flows.  A  fluid  particle  D,  fituated  in  this  plane, 
has  a  motion  D  B,  inclined  to  the  axis  A  B.  This  motion  niay  be  decompofed  into  two,  D  C, 
C  B ;  let  us  fuppofe  that  plane  D  Q  to  delcend  parallel  to  itfelf  along  the  axis,  with  the  motion 
C'B  ;  the  motion  DC  of  the  particle  D  on  the  plane  D  Q,  remains  to  be  examined.  This 
motion  imprefles  u^ion  all  the  particles,  fituated  in  the  plane  D  Q^  a  centripetal  force,  tovirards 
the  centre  C.  •  , 

iLet  any  other  horizontal  motion  whatever,  not  coincident  in  dire£tion  with  D  C,  be  im* 
prefied  upon  the  fame  particles:  Un^er  the  government  of  thefe  two  forces,  the  particles  will 
defcribe  round  the  centre  C  areas  proportional  to  the  times,  and  by  the  equilibrium  of  thefe  '^^  r . ' 

motions,  they  may  aiTume  an  horizontal  circular  rotatioixr.        .  . 

Let  us  imagine,  ^t  during  this  horizontal* circuia(ipn,^<i  particle  D,  in  its  approach  to- 
ward the  centre.  C,  as  iii  a  fpiral,  fhall  defcribe  cirpular'^l^ts,  of  M^iich  the  diaipetcr  is  fuccef- 
fively  diminifiidi^  let  us  odl  the  velocity  of  rotation  pf  the  partid^'De^F?^  9  its'diftance  from  the 
otntresr ;  the^tlme  of  one  r0<vro)ution=/ ;  and  fined"  ihe'^r^milft  be  as  the  tiihes,  we  iball 

\y,-  .\         ;,?  .:-.      *  Hydrod/n.  No.  45»*^'W  :'  • 

'.v.  •  i»-t- V  .S^->i.'-' /  have 


ft 


lf^.ii?r-»P       *  '^  ('+*)  ■ 


14  On  th  uihirBng  EMtd^i^KS'ig  Wattr. 


kaVe  nearly  v=-;  i=r*}  and  the  Mtitilfu'^tforte  4]T  ^^purtidc  D  will  be  s-^.  When  we 

attenttvely  obferve  the  particles  which  revt^Vc  at  tbe'ftir&fce,  of  the  ftiond,  at  M  N,  we  Tee  ' 
dut  the  eSeA  which  really  takes  place  in  nature)  iyaeaAj'tsr*.    Since,  therefore,  die  cen* 

trifugal  force  in  approaching  die  centre  C  inicreaJes  ai|i^,  it  will  become  equal  to  forming   ' 
an  equilibrium  againft  the  upper  preffure  S  D,  w'hi(ii  ^irodiiccs  the  centripetal  force  D  C. 
A  cavicy,  K  R  TH  P  v,  will  therefore  be  formed,  rcAiiul  wftich  theydiirling  £uid  willfupport 
itfelf  by  the  centrifugal  force  of  its  rotation. 

Let  D  Q_P  R  reprefent  a  circular  fluid  zone,  the  particles  of  which'tiM-n  round  the  cavity 
R  P,  according  to  the  law  here  indicated.  Let  the  gravity  of  a  fluid  p^cte  be  =g;  C  R 
=i»i  RD=3;  DX=ai;  X  Z=Ai  and  the  velocity  ofthe  particle  !)=».  Ifthecehtri- 
^gal  force  of  the  particle  D  were  equal  to  its  gravity,  its  velocity,  by  Ac  thorcms  of  Huy-  ■ 

■ '  ^{Cns,  would  be  equal  to  that  of  a  body  fidling  by  gravity  >U|nei  through  die  fpace — ~ — * 
..And  fiiice  u  heavy  body  &11>  in  one  Jecond  through  ^efpac§.jif  i8t  iochessS,  die  vdocity 
':  ,of  ^.pardclc  Don  the  lame  fuppolition  would  be  =  V  (3  S  (a-fi)).  live  centrifu^  force 
i^^;tbe  ciide'is'ak  p*i  die  centrifogal  force  oTD  will  dierefere  ^ly  be  =    ~ "  ^     ■     And 

fihfe  the  fcentrifugal  force  is  =— ;  taking-- — -—--  : 

teroK  wc  fliaU  have  die  centrifogal  force  of  dwdcowiitafD  X  inXc^'X^'''''^]'  '^', . 

2  5  (d+O' — z)» 

M>dltBtofd>efiUmentDX=A+    Tf  ^^t^^\-  WhenxstdieiuetfiW  is  =^01  t»hcnc* 
A  := —■     Takiae  x=^,  die  centrifugal  force  of  the  filament  I^R  will  be=-^-^^ 

it  a+b).    The  quantity  A  ^  is  Ae  gravity  itfelf  of  the  filament  D  R.     The  graVi^of  Uiis- 
filament  ■  therefore  ti*  its  centrifugtl  force  ziw'  (2  «+*).  r  4  <i»8.  ■'■•■■■" 

When  the  fluid  zone,  D  R  PQ,  is  nearer  the  ^witure  E  F,  die  preflure-S  J^  (netwf«B^ 
Valence  die  ccRtrifoga]  force  of  die  zone  ni)ift  alfo  be  increafed  by  diminiHiing  die  nwtius  of 
ihb  Cavity  R  C:  bencc-we  ttUty  determiae  the  nature  of  the  curve  which  forms  the  perpen- 
iicuhr  feftioo  of  the  cavltf-  ife  R  T.  Fot  greater  fim|dicity,  let  us  foppofe  diat  the  fides  t^  the 
velTel  have  the  &me  form  M  D  as  that  of  die  cavity  itfelf,  fo  that  D  R=i  may  be  conftanti 
Let  AC=Xi  and  C  R=:y.  Let  us  fobltittite  y  infleadofajn  the  preoe#ng  forttiiila.  And 
Ance  the  gravity  of  the  filament  D  R,  is  to  the  gravity  of  die  filament  S  Dat :  ^  We  (halt 
have  by  compofitionof  .raiiosj  die.«n«rifugal  force  of  the  filametd  D  R,  to  the  preffure  S  Ds 
k*  V  {2  jt  +  li)  i  ^  X  y^  &;    'Thefe'£i#ntitieftmuf):be.eqiud,  inonler  tofiftildart  ec|uiJibrium> 

We  have  tTier^e^e^r^' — (v^-r*srt^— ):?»  for  the  equation  of  thcr  curve- ^fi'T'.    This 

:':   in  die  {uttj'Soa)^  f()eci.e»in  ^if^pjliilj«n»tion. of  lints  at  ttie^^iti ipi^fti^  $i^Jiii»t* Newton- 
:     Its  convex!*y'i^7*rhfdJp<^^r^  lias  two  «fytoi«bWJ,oiie';*fwM?tl  is  dK  dkifr 

AY,  aod'tluotl^r  fi'tnJ^M^&gbJuig  the  twoeoiaCs;M  ^  toibe  infi.n|^y  diftant. 

•-  '■   ".  ■■''VV' '""'     ".:,'■:''■■;,'■■    '-*  -■■;■'.'•  .-r/  ;'■    ' '  '.  ' 


m- 


'■/;'?',".fv> 


Om  the  whirling  Eddies  of  defienMng^  IVater*  if 

If  the  afiiuned  pofitions  in  this  theory  do  not  abfolutely  coincide  with  nature,  they  approach 
its  effe£b  very  nearly.  It  is  not  only  poflible,  but  there  does  exift  in  nature,  a  whirling  ftreaoif 
of  which  the  cavity  turns  its  convex  pa^:t  to  the  axis,  and  in  which  /=r*  very  nearly,  as  i« 
Ibewn  by  experiment. 

Experiment  xxvi.  Let  the  orifice  E  F  be  opened,  and  any  motion  whatever  be  imprefled  on 
the  fluid,  independent  of  that  which  its  gravity,  and  the  prefTure  of  the  circumambient  particles^ 
lend  to  produce ;  the  turning  immediately  begins,  and  is  feen  to  be  more  rapid  in  thofe  parts  of  . 
the  fluid  which  are  neareft  the  bottom.  The  caufe  of  this  is,  that  the  motion  D  B  is  more 
convergent  and  perceptible  in  thofe  parts  which  are  neareft  the  orifice  E  F*.  The  centri- 
petal force  D  C,  produces  its  efFedi  there  rather  than  at  the  upper  parts.  Thefe  laft  afterwards 
fall  into  the  cavity  which  begins  to  be  formed  below,  by  which  means  chey  alfo  acquire  a  cen- 
tripetal force,  and  the  funnel  or  cavity  opens  to  a  much  greater  height,  than  that  in  which  the 
convergence  of  fluid  filaments  is  obferved  towards  the  orifice  £  F,  in  water  which  is  lefs 
agitated. 

Experiment  xxvii.  Place  a  floating  body  at  the  furface  of  the  fluid,  of  fuflicient  mz^aitude 
to  prevent  the  formation  of  the  cavity.  If  the  fluid  be  much  agitated,  the  cavity  will  take 
place  at  the  lower  part,  and  air  will  introduce  itfelf  through  the  opening  E  F.  Whence  it 
follows,  that  the  prefTure  of  the  atmofphere  on  the  upper  furface  of  the  fluid  is  not  the  caufe  of, 
the  cavity,  which  affumes  the  fhape  of  a  funnel.  The  air  does  not  enter  but  becaufe  it 
finds  an  empty  fpac©  formed  by  a  centrifugal  force. 

Experiment  xxviii.  When  the  fluid  remains  in  a  (late  of  tranquillity  without  eddies,  the  veflcl 
empties  itfelf  in  forty  feconds  ^  but  when  the  circular  motion  takes  place,  the  evacuation  is  ac- 
complifbed  in  fifly  feconds,  more  or  lefs.  It  cannot,  therefore,  be  faid  in  general  terms,  that 
the  whirling  fl:ream  abforbs  and  draws  down  bodies  through  the  opening  E  F  with  more  force 
than  if  no  fuch  circulation  took  place. 

Experiment  xxix.  Pour  aftratum  of  oil  upon  the  water  of  the  veflfcl.  As  foon  as  the  funnel 
fornas  itfelf,  the  oil  rufhes  down,  and  ifTues  out  before  the  greateft  part  of  the  lower  water, 
tipon  which  it  refted.  The  portions  of  oil  partake  lefs  of  the  rotation  of  the  lower  water ; 
having  lefs  denfity,  they  likewife  recede  lefs  from  the  axis  than  the  water ;  in  confequence  of 
which,  as  they  occupy  the  interior  part  of  the  funnel,  and  are  unfupported,  they  flow  out 
firfl. 

Experiment  xxx.  Every  other  fmall  body  which  floats  on  the  water  in  the  veflel,  a<3s  in 
the  fame  manner  a3  the  oil,  provided  its  dimenflons  be  very  fmalL  If  the  volume  of  the  body 
be  fomewhat  greater,  while  it  approaches  the  cavity,  to  fall  therein,  its  extremity,  which  i^ 
neareft  the  axis,  comes  into  a  place  where  the  circulation  is  more  rapid.  This  rapidity  of 
motion  imprefTed  at  one  extremity  of  the  floating  body,  is  tranfportcd  by  the  laws  of  mechanics, 
to  its  centre  of  gravity,  which  is  more  remote  from  the  axis,  in  a  fituarion  where  the  circular 
motion  is  flower,  confequently  the  body  recedes  ifrom  the  edge  of  the  cavity  into  which  it  was 
about  to  fall.  It  returns  a  fhort  time  afterwards,  is  again  repelled,  and  thefe  alternate  motions 
continue  as  long  as  the  circumflances  which  produced  them.     I^ailly,  if  the  body  which  floats 

'    «  Bern(xDillt^  Hydrod.  kdi.  49  S^  I*    Bodutt  arc.  427. 

at 


x6  Eddies  in  the  Jir^'^Mufical  Tramr.  or  UndulatUn. 

at  die  furface  of  the  liquor  after  the  funnel  has  been  formed,  be  of  fufficient  fiie  to  cover  the 
whole  cavity,  it  deftroys  the  funnel  in  the  upper  part,  and  fometimes  alfo  in  the  lower.     The 

I 

reafon  is,  that  the  body  itfclf  cannot  turn  round  its  centre  but  according  to  the  law  v=r;  it 

therefore  deftroys  by  friflion  the  law  v=: in  the  parts  of  the  fluid  in  contact  with  it^ 

and  confequently  it  deftroys  the  funnel  itfelf. 

PROPOSITION  XII. 
The  lateral  communication  of  motion  takes  place  in  the  air  as  well  as  in  water* 

The  ftream  of  air  which  moves  in  the  mid  ft  of  a  body  of  air  at  reft,  produces  undulations 
and  eddies  round  its  current  in  the  fame  manner  as  in  water.  Thefe  may  be  obferved  in  the 
{moke  which  rifes  from  a  furnace,  and  produces  a  remarkable  afped,  when  it  iflues  like  a  dark 
icee  from  an  agitated  volcano.  They  may  likewifc  be  feen  in  the  particles  which  float  in  an 
obfcure  chamber,  when  a  ray  of  the  fun  ftiines  in,  and  the  obferver  blows  through  them. 

If  a  general  wind  comes,  for  example,  from  the  fouth,  it  frequently  happens  that  the  north 
fide  of  a  mountain  is  at  the  fame  time  ffruckby  a  north  wind.  Thfs  partial  and  local  wind  is 
nothing  but  the  eddy  produced  by  the  mountain  itfclf  ailing  as  an  obftacle,  againft  the  prin- 
cipal wind,,  from  the  fouth.  It  is  probably  from  the  lame  reafon,  that  the  wind  fometimes 
a6ls  in  the  contrary  direftion  on  the  fails  of  a  veflTel,  when  they  arc  too  obliquely  prefented  to 
its  ftream. 

The  vapour  of  water  which  ifliies  from  the  eolipile  carries  the  (urrounding  air  with  it,  and 
drives  it  againft  the  burning  coals  oppofite  to  the  ftream  of  aqueous  vapour.  It  muft  not, 
therefore,  be  concluded  that  the  aqueous  vapour  is  itfelf  in  this  cafe  decompofed  to  maintain 
the  combuftion  of  the  charcoal. 

It  is  known  that  the  flues  of  chimnies  aflift  the  rifing  of  (moke  by  their  figure;  concerning 
which,  we  have  drawn  fome  indu£lions,  in  the  feventh  propofition. 

In  organ  pipes,  the  air  which  iflues  out  of  the  fide  opening  (lumiere)  rubs  laterally  againft; 
the  extremity  of  the  column  of  the  air  included  in  the  pipe.  It  rubs  it  on  one  fide  in  the  longi- 
tudinal dire£^ion,  and  is,  as  it  were,  an  elaftic  file,  a£ting  upon  an  elaftic  furface.  Though' 
the  column  of  air  be  fluid,  its  parts  are,  however,  fo  hx  intermixed  together,  that  the  tremulous 
motion  excited  at  the  place  of  fri&ion,  is  (bon  communicated  laterally  dux)ugh  the  whole  thick- 
nefs  of  the  column,  which  receives  vibrations  of  fuch  a  kind,  that  they  are  an  equilibrium  with 
each  other,  and  with  the  velocity  of  the  ftream  which  affords  die  fri&ion.  For  this  efie6t,  it 
is  requifite  that  the  column  ftiould  divide  idelf  at  different  pomts  or  nodes  dlftributed  through 
the  length  of  the  tube*.  It  is  by  repeated  adions  that  the  wind  which  iflTues  from  the 
fide  aperture  imprefles  at  length  upon  the  whole  column  contained  in  the  pipe,  a  movement 
of  vibration  greater  than  that  which  the  laws  of  impulfe,  and  of  the  lateral  communication, 
would  permit  it  to  make  by  a  fingle  impulfe.  In  the  hautboy,  and  other  fimilar  inftruments, 
having  a  mouth -piece,  or  reed,  the  caufe  which  excites  the  tremulous  motions,  does  not  aft 
fideways  on  the  air  contained  in  the  pipe,  but  ftrikes  the  column  direSly  in  the  midde:  for 
which  reafonj  it  communicates  its  vibrations  with  fo  much  the  more  effeft  to  the  whole  mafs. 

*  Memoires  de  TAcad.  an.  1762,  page  431. 

la 


Onihi  FUratiim  which prpduci Soimd.^^Ecb9^  t*j 

In  like  circamftances  the  force  of  found,  which  is  propagated  in  the  atmofphere,  depends  on 
the  magnitude  of  the  fedion  of  the  air  which  is  at  the  extremity  of  the  pipe,  and  the  amplitude 
of  the  vibrations  of  this  fe£lion.  It  is  this  furface  which  ilrikes  the  atmo^here»  and  commu- 
nicates the  pulfations*.  For  this  reafon,  conical  divergent  pipes  afford  a  ftronger  found  than 
lliofe  which  are  cylindrical ;  and  thefe  laft  afford  a  ftronger  found  than  pipes  which  are  conicallj^ 
ccmvergent.  The  firft  caufe  of  the  found  which  a£ts  at  the  mouth  end  of  die  pipe  wouU 
neveti  of  itfelf,  excite  fuch  ftrong  pulfadons  in  the  atmofphere,  as  it  does  excite  )>y  the  lateral 
cdmrnuoication  in  die  air  contained  in  a  divergent  conical  pipe. 

The  explanation  of  this  phenomenon  may  be  underftood  by  obferving,  ift.  That  if  a  number 
t)f  elaftic  bodies  be  difpofed  in  progreffion,  the  firft  will  imprefs  upon  the  laft,  by  the  intermedium 
of  the  others,  more  velocity  than  would  be  communicated  by  the  immediate  flrojce.  %.  The 
Tihrations  excited  in  the  pipe,  have  a  certain  permanence  which  permits  theip  to  receive  aa 
increafe  of  force  by  the  united  effe(Sl  of  fuccei&ve  impulfions;  whereas,  in  the  openatmoiphere 
every  puliation  is  tranilent  and  alone*. 

is  cot  the  augmentation  of  ^(bund  in  the  fpeaking  trumpet,  in  part  owing  to  the  (ame  caufe 
of  the  lateral  communicadon  of  motiont  rather  than  to  the  mere  r^fleftion  c|f  the  /(porous 
lines  from  the  (ides  of  die  tube  itfelf? 

I  call  thofe  nfonani  vibradons,  whidi  take  (dace  in  a  tube  when  fi>i|nd  is  ^xcil^;  and  I 
call  diofe  propagated  vibradons,  or  pulfadons,  ^ch  tranfmit  the  found  through  the  atmofphere. 
I  have  already  pointed  out  a  difference>  which  appears  to  me  to  take  place  t^etweea  thefe  two 
lands  of  vibradons;  namely,  that  the  firft  have  a  certain  permanence  and  conneflion  with 
each  other,  fo  that  the  latter  excites,  fupports,  and  reinforces  the  former ;  whereas*  the  puUa« 
tiofis  which  fucceed  each  other  in  the  atmofphere  by  the  repeated  a£tion  of  the  i^efctnant  body 
are  fingle,  and  independant  of  each  other. 

But  the  following  is  a  much  more  remarkable  difference  between  thefe  two  kinds  of  vibra- 
tions. When  at  the  extremity  of  a  pipe  A  B  C,  a  refonant  vibradon  is  made  in  the  fedlion 
of  air,  B  C,  fig.  2.  Plate  VIII,  vol.  IL  experience  fhews  that  this  vibration  becomes  the  centre 
of  pulfedons  propagated  all  round  in  P  S  Q.  For  on  whatever  fide  the  obfcrver  is  placed, 
whether  at  P  or  at  Q,  he  will  hear  the  found  of  the  pipe  ABC  nearly  as  much  as  at  S.  But 
n^hen  diere  is  no  pipe,  and  the  vibration  at  C  B  is  a  fimple  pulfaticn  propagated  through  theopen 
air  from  A  to  B,  in  this  cafe,  the  pulfadon  is  not  propagated  laterally  and  completely  to  P  and 
Q^like  the  refonant  vibration ;  b^t  iscontained  almoft  entirely  in  the  limits  B  Z  and  P  Y,  with 
adivergence  of  between  15*  and  20  degri^es.  This  fad  has  bceijk.difputed  by  various  philofophers^ 
but  it  cannot  be  queftioned,  fmoe  it  is  well  known  that  we  flo  not  hear  the  echo,  or  refledted 
found,  from  a  plain  furface,  unlefs  we  place  ourfelves  in  the  line  of  ref!e£tion,  or  very  near  it 
If  the  puliation  of  the  echo  "were  ^propagated  all  round,  before  the  refledingfurface^  diverging 
from  thence  as  centre,  ought  we  not  to  hear  the  echo  in  every  fituadon  whatever  before  that 
refleding  furface?  We  muft  therefore  admit,  with  regard  to  fonorous  pulfadons  propagated 
in  the  atmofphere,  certain  excepdons,  and  even  limits,  with  regard  to  the  latera)  communica- 
tioli  of  modoti  which  we  have  ppinted  out  in  the  firft  propofition,  and  in  the  fifth,  with  regard 
to  water.  ^        •        .        • 

*  It  is  known  that  the  material  c^  Ivliich  a  pipe  is  made  ^oet  not  peccepttl»ly  aSe^  ths  found. 

Vol*  UL— April  1799*  D  Addition 


1» 


«      -  .  . 

On  the  contra^ed  Stream  and  Vehcity  ef  fp^uting  Flmiu 


Addidon  rejpe^ing  the  coniraSied  Fein* 

Miich  has  been  written  concerning  the  convergent  direAions  aiTinned  by  the  particles  of 
a  flaid  contained  m  a  vefleK  previous  to  their  being  emitted  through  an  aperture  in  the  fide 
of  the  veflTel  itfelf,  atid  concerning  the  form  of  the  contra Aed  vein  which  is  thus  produced* 
The  tefle&ions  and  experiments,  which  I  fliatl  proceed  to  give,  >  noay  aiFord  ibmc  farther  ex^ 
pl^atlon  in  this  refpe£l. 

1  (hail  begin  by  ddfending  the  fundamental  dodlrine  of  hydraulics  s^atnfl  the  opinion  of  a 
learned  man,  difKnguifhed  by  bis  labours  and  his  zeal  for  the  advancement  of  fcience: 
Lorgna,  the  founder  of  the  Italian  fociety.  He  pretends  *  that  the  contraded  vein  is  nothing 
elfe  but  the  continuation  of  the  Newtonian  cataract  and  that  the  celerity  of  the  fluid,  ifliiing 
from  an  orifice  in  a  Ain  plate,  is  much  left'  than  that  of  a  body  which  fidls  from  the'heig^ 
of  the  charge*  . 

Let  M  D>  fig.  22,  PI.  XXII,  vol.  II,  rcprefent  the  axis  of  the  vein  which  iffues  from  & 
The  radius  of  die  circular  orihce  BC  =  BD=liMB=:a.  Lorgna  pretends  thai!  o^f^  0=: 
H  B,i8  the  height  which  wouM  produce,  in  an  heavy  body,  die  velocity  of  efflux  in  B  C(  he 
fupports  this  propofition  by  computations  deduced  from  die  mutual  adion  of  the  particles  of 
the  fluid  contained  in  the  reffel.  But  afcer  having  feeii  the  fiiilure  of  the  efibrts  of  the  greatefl 
geometers  on  this  fubje^l,  we  ought  to  mifirufl  all  thefe  demooftrations  founded  on>  mechanical 
principle,  very  true  in  themfeWcs,  but  of  which  the  application  to  an  infinity  of  bodies,,  whidi 
move  ajid  are  prefled  in  every  direction,  becomes  extremely  difficult,  if  not  impoffiblew 
Let  us  fee  whether  the  theory  of  Lorgna  agrees  with  experiment.  Suppofing  the  veloctty  of 
the  fluid  at  B,  arifing  from  the  elvation  H  6=0,472  ay  the  velocity  of  die  fame  fluid  in  D 
will  be  increafed  in  the  ratio  of  VIiF  *  VHd  i  and  the  vein  in  D  will  be  contra£led  in  the 

&meratio:  whence D£=  V  *( -^^HiiL  ).  which  is  the  formula  of  die  hyperbolic  conoid  of 

Newton.  ^  If  diis  be  the  fole  caufe  of  the  contra«5lion,  the  dimenfions  of  D  E  ought,  very  nearly, 
to  agree  with  diis  figure  when  examined  by  experiment  But  they,  in  reality^  differ  from  it 
very  much^  as  may  be  fieen  in  the  following  table. 


Audiors  of  die  experiments. 

Pdeni  (de  Caflellis  ^  35.) 
Mtchdotti    (Sperim.  Idrai/l. 
tom.  I.  exper.  46 ;  tom»  II. 
exper.  4)        •         •        • 
BofTut  (Hydrodyn.  art  437 

cxpen  5)         .         . 
Myfel^  with  35  inches  charge 
sind  an  horizontal    circular 
of  18  lines  in  diameter 


Value  of  D  £  found  by 

adual  meafurement* 

0^79 


Value  of  Id  £  calculated  by  the 
preceding  fi)rmula» 
0,97 


•       o>8o 


•       Q>8i8 


.       o>798     • 


o>99 


0,99 


—1^ 


S9*4 


:  ( 


^  n. 


*  ( t )    Mem.  della  fbcicta  lullins,  ?ol%  IV. 


H 


Oh  the  cMtra^i  Stream  and  Vehcity  offymtin^  Fluids.  19 

It  is  evident  that  the  contrac^ipn  of  the  vein,  as  found  by  experiment,  .is  incomparably 
greater  than  can  be^  produced  by  the  acceleration  of  gravity,  eyeh  in  defcending  ftreams.  But 
what  can  we  fay  of  horizontal  and  alcqiding  jets,  in  which,  afluredly,  the  acceleration  of  gra- 
vis does  not  take  place,  but  in  whicb^  neverthelefs,  the  contra£lion  is  obferved*  nearly  in  the 
fame  manner  as  in  defcending  currents  ?  The  contraction  of  the  ftream  is,  therefore,  tery 
different  from  the  Newtonian  hypcrboloid, 

Defirous  of  proving  that  the  vein  does  not  polTefs  the  whole  velocity  arlHrig  Iroih  Sie  hei^jht 
of  the  fluid  above  the  centre  of  the  orifice,  Lorgna  relates  the  experimeiiti  of  Kraft*, 'Which  arc 
hot  applicable  to,  thcr  queftion,  becaufe  they  were  made  with  cylindrical  pipes ;  aiid  we  have 
iecn,  that  fuch  pipes  always  deftroy  part  of  the  velocity,  of  the  fluid ;  confequentty,'  we  cannot 
eftablifh  any  rule  from  them  which  ihall  apply  to  orifices  through  thin  platesf .  He  wMhes  not 
to  determine  the  velocity  of  afcending  jets  by  the  heigh t'toVhich  they  rife,  becaufe  he  is  appre- 
benfive  that  the  preceding  part  of  t(ie  ftream  or  jet  is  urged,  and  fupported  bj^  the  fucceeding 
'{MUt  nearly  to  the  height  of  the  charge.  Neverthelefs,  if  wt  interrupt  the  jet  all  at  once,  the 
laft  portions  of  water  fly  to  the  fame  height  as  thofe  which  preceded  them,  without  having  any 
continued  column  of  the  fluid  below  to  follow  and  fupport  them  :  thefe  laft  pordoils  muft  con- 
fequendy  have  received,  at  their  paflage  through  the  Orifice,  all  the  velocity  which  was  neceflfary 
to  raife  them  nearly  to  the  furiace  of  the  fluid  in  the  refervoir. 

Let  us  confine  ourfelves,  if  it  be  thought  proper,  to  horizontal  jets ;  the  experiment,  which 

•  ■  ■  .. 

I  have  related  as  a  term  of  comparifon,  appears  to  me  to  be  decifive.  Under  the  charge  of  32,  j 
inches  the  vertical  line  PM,  fi&.  i,  PL  VIII,  vol.  II,  being  54  inches,  the  horizontal  line 
"M  N  was  always  8I95  inches,  which  was  only  2  inches  lefs  than  it  would  have  been  if  the  jet 
li^d  preferved  in  the  direction  of  the  horizon,  all  the  velocity  which  a  heavy  body  Acquires  in 
miing  from  the  height  of  32,5  inches.    The  diameter  of  the  contraiSed  vein  was  14,3  lines 
Tery  nearly.     Since  the  quantity  of  81,5  inches  in  MN  fuppofes  in  the  contrafted  vein  a  ve- 
locity of  149,5  inches  per  fecond  i   this  number  multiplied  by  the  area  of'ihe  conttmAed 
vein  itfelf,  gives  the  expenditure  of  4  cubic  feet  in  41  feconds  of  time,  Which  is  alfo  the  refult 
of  experiment    .We  have,  therefore,  three  meafures  determined  by  experiment,  which  agree 
and  mutually  confirm  each  odier ;  namely,  the  quantity  M  N,  the  cohtraftion  of  the  ftream, 
aod  the  time  ot  expenditure.    And  fince  the  quantities  obferved  by  BoflTut,  Michelotti,  and 
^Potent,  give  nearly  die  &me  refidts,  it  can  no  longer  be  doubted ;  i,  That  the  contraAion  of  the 
ftream  is  nearly  0,64  of  the  orifice ;  2,  That  the  velocity  of  the  contrafled  view  is  nearty  the 
iame  as  that  of  a  heavy  body  which  may  have  fallen  through  the  height  of  the  charge.  ' 

Thefe  two  experimental  principles  are  true  in  aH  cafes  where  the  orifice  is  confiderabljr  fimali 
in  proportion  to  the  feAion  of  the  refer  voir,  where  that  orifice  is  made  through  a  diin  plate,  and 
the  internal  afiHux  of  the  fluid  filaments  is  made  in  an  uniform  manner  rbund  the  orifice  itfelf. 
But  what  would  be  the  confequence  if  this  internal  afflux  ftiould  be  modified  in  a  manner 
Afferent  from  what  ufually  happens  ?    The  following  experin^ents  wc^e.  made  with  the  in« 

•  A6ti  Pctrop,  vol.  8. 

>  TorriceiU  took  notice  of  this  difiirence  at  page  168,  of  hit  works,  <*Quofi/Bfcnmque  auif  Qi.aqus  per  tubum 
^  lateatem  dccurrens  per  anguftias  trapfire  debucrit,  falfa  omnia  reperics.*' 

D  2  tcntioii 


io.  kmarkM  flmmina  rffiovilng 

trntion  of  afccrtuning  Ibme  of  the  moft  remarkable  efieds  of  diefe  particular  modifications  in 
the  dire£lion  of  the  fluid  filaments,  which  prefs  each  other  in  order  to  ptb  dirough  die  orificieti 

ExpmnUnt  xxxi.  In  the  orifice  A  C  B  D,  fig.  2i,  PI.  XXII,  vol.  II»  die  two  fides  A  B  are 
parallel  to  the  horizon ;  the  extremities  C  D  are  rounded :  die  width  of  diis  aperture  is  lels 
than  two  lines,  its  length  1 8  lines,  and  the  charge  32,5  inches.  The  fe^on  of  die  ftreanv 
which  ifliies  firom  diis  orifice,  firft  aflumes  die  form  E  F ;  after  which,  the  two  extremides 
£  F,  approaching  nearer  and  nearer  to  fwell  die  middle  part  of  the  feftion  of  the  (beam,  at  4,5 
inches  diftance  from  the  orifice,  acquires  the  <|uadrangular  form  G  H,  The  ftream  aifter*^ 
wards  extenidfi  itielf  in  the  perpendicular  dire£lion  in  die  form  of  a  large  fiui  K  L* 

I  have  repeated  die  experiment  by  placing  the  longitudinal  axis  of  the  orifice  £  D  verdcalljr. 
In  this  caie  the  Cune  phenomena  were  produced  \  £  F  becoming  vertical,  and  K  L  horizon* 
tal,  both  prefervii^  dieir  form. 

The  fluid  filaments  which,  ifluing  out  of  die  orifice,  pals  near  the  two  opp6fite  borders  A,By 
are  very  near  eadi  other,  being  convergent,  tend  to  unite  at  a  very  ihort  diftance  from  did 
orifice  itfel^  The  filaments  C,  D,  are  more  remote,  and,  perhaps,  left  convergent  i  they  cannot 
unite  but  at  a  greater  diftance  dian  the  two  former.  In  diis  cafe,  therefore,  there  are  move- 
ments which  tend  to  form  two  contradions,  the  one  nearer,  and  the  other  more  remote  firbm 
the  orifice.  Thefe  two  contra£bion$  counterbalance  each  odier  in  part ;  their  mutual  oppofition 
carries  diic  effed  G  H  to  a  diftance  five  times  greater  than  that  of  the  contra&ed  vein  of  a 
-circular  orifice,  havuig  a  diameter  of  the  (ame  breadth  as  diat  of  this  orifice. 

In  this  experiment  we  fee  the  caufe  of  a  phenomenon,  which  has  been  pbferved  in  fome  par- 
ticular cafes  by  Poleni  and  others,  without  giving  the  explanation.  In  every  orifice  of  a 
right-lined  figure  through  a  thin  plate,  the  angles  of  the  contraded  vein  anfwer  to  the  fides 
of  the  orifice,  and  the  contrary.  When  die  quadrangular  orifice  has  the  fituation  M  N  O  P, 
the  greateft  contradion  of  the  ftream  is  made  at  a  greater  diftance  than  in  a  circular  aperture ; 
It  afiumes  the  form  and  fituation  Q^R  S  T.  The  reafon  is,  that  the  oppofite  angles,  M^  P, 
are  morere  mote  firom  each  other  than  the  fides  I,  V,  whence  the  (ame  thing  happens  as  in  the 
long  orifice  A  C  B  D.  In  the  fiune  manner,  the  triangular  orifice  in  the  fituation  X  pro- 
duces a  contraAion  of  the  form  and  in  die  fituation  Z,  &c. 

Expcrinunt  xxxii.  The  orifice  being  the  horizontal  cleft  C  D,  fig.  21,  the  place  G  H, 
or  moft  contracted  point  oifthe  ftream,  was  found  to  be  diftant  firom  the  orifice  as  in  the  follow- 
ing table:  . 

Diftance  of  the  greateft  coatradjog 

Lines. 


Hnght  of  the  charge  abo^ 

Inches. 

IP 


53 
4P 


1.  4  *.  •f 

36 


The  long  orifice  C  Diexhibils  to  us,  under  an  enlslrged  dhnenfion,  the  diftance  of  die*fen« 
Iraftcd  vein  from  die  orifice.    By  this  means,  die  foregoing  table  ihews  us>  in  a  very  fenfible 

manner. 


tuiiiier,  tlutf  tbe  cmtnftieo  of  die-ftream  tik 
than  in  tlK)fe  whidi  hate  but  Gtde  dcvitioii. 

Expmnunt  xxxiii.  To  the  ceatit  of  the  circular  orifice  A  B^  fig.  23,  fermed  in  a  thin 
platcy  I  ilifpofed,  widiin  die  rdervotr^  die  cone  of  metal  D  G  £9  vrith  a  cjdindrical  part 
C  F  G  D,  in  focfa  a  manner  that  die  cone  was  moveable  along  its  own  sna  I V,  and  its  finnmiti 
£,  could  be  protruded  more  or  left  dirough  the  orifice  A  B^  .ap£rpach.ing  or  receding  from  die 
point  V.  ThemealUres  in  lineswere  ABsiS;  IE=24;  bG=:27;  C  D=8.  This 
apparatus  was  applied  to  the  orifice  P,  fig.  i».  Plate  VIII ;  the  chat^  being  32,5  inches.  The 
refults  were  as  in  the  follon^ing  table. 


Quantity  £  X,  by  whidi 

1 

the  fummit  of  die  cone 

Diftance  of  die  con* 

Diftance  oTMN. 

Time  of  expenditure 

prcjeds    beyond    the 

traded  vein. 

of  4  cubic  feet 

line  A  B. 

• 

Lines. 

Linis. 

Inches. 

' 

11,1 

9>» 

76 

85" 

6,6 

">3 

77.S 

53 

a 

H 

78.S 

43 

The  cone  removed. 

>4.3 

8i,s 

41 

I  intend-  to  repeat  and  vary  diis'  escperimenty  In  ot^t  to  difcover  die  caufe  of  the  finguhur 
phenomena  Vi^ich  it  prefents. 

£0pirimeni  yxxiv.  The  orifice  being  a  iemi-circl^  Plate  XXII,  fig.  24,  vol.  II,  having  the 
diameter  A  B,  11,2  lines,  I  applied  within  the  vefiel  a  plane  Q^A  B,  perpendicular  to  the 
plate  in  wiuch  the  orifice  was  made.  The  line  A  B  was  perpendicular  to  the  horizon,  ahd 
the  charge  32,5  inches^  The  jet  deviated  in  the  horizontal  direfiion  in  P  F  G,  departing; 
lirom  die  axis  C  £  towards  the  fide  on  which  the  plane  Q^P  was  placed.  The  angle  F  C  ^ 
was  9^  5',  and  die'angle  F  CG  was  jjb^.  The  vertical  fedion  of  the  jet  had  the  fi^rm  K  h, 
(bdiat«belargeftpa]tofthiej)6ewasMF.  The  fimr  cubical  feet  of  water  ifltied  out  in  206 
feconds. 

Thefefidts  of  this  dctierimeM  are  analogous  tothoie  of  the  experhnents  xxxi  and  xxxitl. 

Sxfirimeni  xxxv,  Citfeen  Boida,  in  a  vtry  interefting  memoir*,  rehtes  a  peculiar  pheno* 
nienon,  of  wbich  he  has  grrena  very  fimple  demonftration,  from  die  principle  of  the  equality 
of  prefl«re,  which  HMk  exert  in  every  iTireAion*  It  is  that,  if  the  extremity  of  a  cylindrical 
tube  be  pufted  into  the  interior  part  <of  the  refisrvoir,  die  contrS&ion  of  the  vein  is  greater,  and 
die  expenditure kis, than  if  thefime  tube  be  applied  to  the  fide  of  theveflel.  I  have  repeated 
tUs  experiment,  and  obftrved  a  fintiar  refidt  when  die  tube  was  cyfindriod  from  one  end  ta 
the  other,  like  that  made  ufe  of  by  die  audior,  and  when  the  water  was  made  ta  flow  out  in  a 
full  ftream*  I  afterwards  gave  to  the  interior  extremity  of  die  pipe  the  form  AC,  fig.  4,  Plate 
VIII,  vpL  II,of  the  common  cootradsd  veins ;  in  thb  cafe^  there  was  na  longer  any  renuu-k' 


*  Mcmmret  de  TAcad.  17^6. 


abfe 


/ 


aa  AfecbimiiiilJ^aMcmion  ef  Lint  ^  Uatu    .. 

^e  difference  between  dlQ  twp  ei^enditureSi  in  the  two  fituations  of  tHe  tube.     For  when 
-the  end  AC  was  pulhed  into  the  interior  part  of  the.  referyotrt  the  full  tube  t^ordedp  in  8 1,  feco^ 
iheiame  q^ianttty  of  water  ^^  was  furniihed  in  Sofeconds,  when  it  was  applied:  to  the  fide  of 
4he  veflel.    It  may  be  pfefiimedi  that  if  the  part  A  C  had. more  perfe£lly  polU&d  the  form  of 
the  contnuSltd  vein,  this  lligbt  difference  of  one  fecond  wpuU  have  (li(appeaj:ed*. 


m^ 


.1.1 


^n  the  Mechanical  Fabrication  of  Lint^  and  the  ManufaSure  of  Hati.    B^  M  Z, 

To  M*.  NICHOLSON. 


O 


STR, 


N  the  fuBjcA  of  drei&ng  lint,  by  engines,  the  rerult  of  my  inquiries  is  the  following  :«^It 

"was  attempted  by  a  Mr.  John  Swaq,  of  Whitehaven^  C^umberland  :.the  objeAion  made  againft 

it  was,  ^ha|t  it  broke  the  lint :  could  any  of  your  corfc^pondents,  in  that  part  of  the  country, 

t>btatn  a  drawing  or  model  of  thcmachine ;  as  it  may  be  very  likely  fome  alteration  in  it  might 

accompliDi  the  purpofc  ?  On  the«ther  fubjed  of  inquiry— Uats,  a  Mr*  Saxton,  45  and  46,  Queen« 

ftreet,  Southwark,  is  concerned  with  a  houfe  in  the  cotyitry,  who  makes  hats  with  engines, 

but  %uhere\it  may  pol&bly  inform,  I  do  not  know  myfelf.     Meflrs.  i)avis.  Welts,  and  Martin^ 

Jate  of  Stocl^poft,  now  fomewhere  in  Kent,  make  ufe  of  «iigifties  for  plaiting  hats.     There  is 

alfo,  I  underftand,  another  company  at  Stockport,  names  unknqwn,  who  ufe  engine^  to  makp 

foldiers'  hats:  how  far  might  all  thefe  be  improved,  fo  a^  to  complete  the  procefs  ?     HatS  are 

^vided  into  three  forts  felts,  thofe  made  of  plain  wool^cordies,  cordebacks,  writ  cordies,  thofe 

covered  or  otherwife  with  codies  wool  .(wool  ftript  from  the  (kins  of  thofe  Iambs  that  die  in 

yeaning,  called  by  the  Scotch,  mort  wool) ;  and  the  third  fort  is  called  ftuff^,  Caroline,  or  caftor«* 

•iiats,  that  is,  hats  covered  with  beaver,  or  beaver  and  hares*  wool  mixed :  how  did  the  fecond 

fort,  cordies, obtain  that  name?  The  reafon,  I  have  heard,  is,  they  were^rft  n>ade  in  a  town  of 

France,  whole  name  comes  near  that  this  kind  of  bat  has  obtained^  if  fo,  what  town  is  it? 

Why  are  the  third  fort  called  Carolines  f  Thefe  queftions  may  be  thought,  at  firft,  trifling ;  but 

when  «the  hiftory  of  a  manu&Aory,  from  its  origin,  is  fought  for,  it  fomietimes  happens  that 

the  various  names  of  the  article,  in  queftion^lead  us  to  the  difcovery.  '  Mafters,  in  general,  are 

divided  about  the  u(e  df  galls  in  their  dying :  it  would  be  well,  if  a  regular  plan  could  be  adopted 

for  the  proportionx>f  -ingredients,  whether  of  wool  or  ftuiF;  for  this  we  muft  look  up  to  the 

chemifts  of  the  prefiait  day.    AUpw  me  to  a/k^theoia.queftiQn,  in  .the  refolving  of  which) 

the  dye-houfes  in  the  country,  are  much  interefted.    By  what  mixture  of  ingredients^  do  the 

London  dye-houfes  obuina  black  xolour  fo  much,  fuperior  to  tbofo  Of  the  country?  D/. 

•  Here  concludei  the  interefting  rt(tixt\ie%  of 'Cittzeii  Vehturi  on  ^uids.  At  the  end  of  his  publicaticn  he  has 
^iven  a  fliort  fammary  of  the  contents,  which,  on  account  of  the*  length  of  this  conctuding  part,  I  diall  defer 
-to  the  next  number;  I  take  this  Q|q;>onttiiity  of  announcing,  that  Mr.  Taylor,  bookfellcF  in  Holbom,  haa  ap- 
plied to  me  for  permiffion  to  reprint  the  tranflatios  from  this  Journal,  and  that  it  will  accordingly  appear  ia 
the  forn  of  an  odtavo  pamphlet. 

Aikin, 


JtccHmi  of  thi  Mwit/aifire  df  Hhu  t3 

Aikin,  in  his  hiftory  of  Mancheftcr,  (ays,  that  in  that  part  of  the  country,  the  hatters  boil  the 
felt  hats,  after  bowing  and  balbning  in  a  mixture  of  **  ingredients  of  native  growth.'*  I  wifli 
the  do^toi*  would  inform  us,  what  he  means  by  that  phrafe  ?  as  die  cordics  about  Manchefter, 
are  better  got  upy  than  thofe  in  many  odicr  places,  and  it  may  be  owing  to  fome  vegetable  put 
into  the  pan  during  boiling. 

I  am.  Sir, . 

Your*8,  &c. 

N.  L. 


B 


V. 
Report  and  Ohfervations  on  the  Art  of  Hat-makings    W.  N*  '], 


Y  a  private  letter  of  recommendation  from  the  refpe(Etable  aiithor  of  the  foregoing  com- 
munication, I  vifited  the  manufactory  of  MefTrs.  ColIinfons%  hatters,  in  Gravel-lane,  South** 
wark ;  and  conclude  it  will  be  intereftiifg  to  many  of  my  readers,  to  fee  an  account  of  the 
procefs. 

The  materials  for  making  hats,  are  rabbits*  fur,  cut  ofF  from  the  Ikihi  after  die  hairs  have 
been  plucked  out,  together  with  wool,  and  beaver.  The  two  former  ai'e  mixed  in  various  pro^ 
portions,  and  of  different  qualities,  according  to  the  value  of  the  article  intended  to  be  made; 
and  the  latter  is  unlverfalTy,  as  I  take  it,  ufed  for  facing  the  finer  articles,  and  never  for  the 
body,  or  main  flufE  Experience  has  jfhewn  that  thefe  materials  cannot  be  evenly,  and  well  felted 
togethen  unlefs  all  the  fibres  be  fim  feparated^  or  put  into  the  fame  ftate  with  regard  to  each 
other.  This  is  the  ebjefi  of  the  firft  procefs,  called  bowing.  The  material^  without  aiiy 
previous  preparation  *,  is  laid  upon  a  platfbrm  of  wood^  or  of  wire,  /bmewhat  more  than  four 
feet  fquaref,  called  a  hurdle,  which  is  fixed  againft  the  wall  of  the  work-fhop,  and  is  enlight- 
ened by  a  finall  window,  and  feparated  By  two  fide  partitions  from  other  hurdles,  which  occupy 
the  reft  of  the  fpace  along  the  wall.  The  hurdle,  if  of  wood,  is  made  of  deal  planks,  not 
quite  three  inches  wide,'  difpofed' parallel  to  the  wall,  and  at  the  diftance  of  one-fortieth,  or 
one-fiftieth  of  an  In^h  firom  each  othei:,  for  die  pur^ofe  of  fuffcring  the  duft,  and  other  im- 
purities of  the  fiuff,  to  pafs  througli ;  a  purpofe  ftill'  more  eiFe£tually  anfwered  by  the  hurdle 
•f  wire. 

The  workman  is  provided  with  a  bow,  a  bow-pin,  a  bafket,  and  feveral  cloths;.  The  bow 
is  a  pole  of  yellow  deal-wood,  between  ieven  and  eight  feet  long,  to  which  are  fixed  two 
bridges,  fomewhanike  that  which  receives  the  hair  in  the  bow  of  the  violin.  Over  thefe  is 
ftretched  a  catgut,*  about  one-twelfUi  part  of  an  inch  in  diicknefs.  The  bow-pin  is  a  ftick 
widi  a  knob,  and  is  ufed  for  plucking  the  bow-ftring.  The  bafket  is  a  fquare  piece  of  ozier 
work,  confif(ing  of  open  ftrait  barswidi  no  croffing  or  interweaving.    Its  length  acrofs  the 

*  Some  writers  mention  a  partial  wetting  of  the  for  while  on  the  (kin ,  by  lightly^  fmearing  it  with  a  fblution 
•f  mtrate  of  mercury  to  give  it  a  curl.    Mcffirs.  CoUinfons  do  not  ufe  it,  nor  any  other  preparation. 
t  I  give  the  numerical  eftimatei,  not  from  mtafure,  but  by  memory. 

kkr$ 


bars  may  be  about  two  feet,  and  its  breads  eighteen  inchci.  The  (ides  into  vhich  the  bars 
are  fixed,  are  flightly  beaded  into  a  circular  curye»  fo  tbat  die  bafket  may  be  fet  upright 
on  one  of  thefe  edges  near  die  right  hand  end  of  die  hurdle,  where  it  ufually  ftands.  The 
clodis  are  linen,  and  dyed  of  a  dark  olive  brown.  Beildes  thefe  implementSi  die  worlonan 
is  alfo  provided  with  brown  paper. 

The  bowing  commences  by  (hovelling  the  material  towards  the  right  hand  partition  with 
the  baflcet,  upon  which,  the  workman  holding  the  bow  horizontally  in  his  left  hand,  and  the 
bow-pin  in  his  right,  lightly  places  the  bow*ftring,  and  gives  it  a  pluck  widi  the  pin*  The 
ftring,  in  its^return,  (Irikes  part  of  the  fur,  and  caufes  it  to  rife,  and  fly  pardy  acrofs  the  hurdle 
in  a  light  open  form.  By  repeated  ftrokes,  the  whole  is  thus  fubjefted  to  the  bow,  and  this 
beating  is  repeated  till  all  the  original  clots  or  mafles  of  the  filaments  are  perfe£Uy  opened  and 
obliterated.  The  quantity  thus  treated  at  once,  is  called  a  batt^  and  never  exceeds  half  the 
quantity  required  to  make  ohe  bat. 

When  the  batt  is  fufliciemly  bowed,  it  is  ready  for  hardining^  which  terfn  denotes  the  firft 
commencement  of  felting.  The  prepared  material  being  evenly  di(po(ed  on  the  hurdle,  is 
Jirft  prefled  down  by  the  convex  fide  of  the  baiket,  then  covered  with  a  doth^  and  preiTed 
fucceiSvely  in  its  various  parts  by  the  hands  of  die  workman.  The  preiTure  is  gende,  and  the 
hands  are  very  ilighdy  moved  back  and  forwards  at  the  laqie  time  through  a  fpace  of,  perhaps,  a 
quarter  of  an  inch,  to  fnvour  die  hardening  or  cntaxiglin^  of  the  fibres*.  In  a  very  (hort  time,  ii^- 
deed,  die  ftuflF acquires  Aifficient  firmne(s  to  b^ar  carefiilhandling.  The'doth  is  dien  taken o^ 
and  a  iheet  of  paper,  with  its  corners  doubled  in,  fo  at  to  ^ve  tc  a  triangular  outline,  is  laid 
upon  the  batt,  whidi  laft  is  folded  over  the  paper  as  it  lies,  and  its  edges,  meedng  one  over 
the  other,  form  a  conical  cap.  The  joining  is  foon  made  good  by  prdflTure  widi  the  haqc^ 
on  the  cloth.  Another  batt,  ready  hardened,  is  in  the  next  place  laid  on  the  husdle,  and  the 
cap  here  mentioned  placed  upon  it  with  the  joining  &wnwards«  This  laft  batt  being  alfp 
folded  up,  will  confequendy  have  its  place  of  jundion  diametrically  oppofite  that  of  the  inne» 
felt,  which  it  muft  dierefore  greatly  tend  to  ftrengdien.  The  prindpal  part  of  the  hat  is  dius 
put  together,  and  how  requires  to  be  worked  widi  die  hands  a  confiderable  time  upon  the 
Jiurdle,  the  cloth  being  alfo  occafionally  fprinkled  n^th  dear  water*  Duru^  die  whole  of 
this  operation,  which  is  called  bafrning^  the  ardcle  b^comef  firmer  and  firmer,  and  contra&s 
in  its  dimenfions.  It  may  eafily  be  underftood>  fh^t  die  diief  u(e  of  die  paper  is  to  prevent 
the  fides  from  feldng  togedier. 

The  bafoning  is  followed  by  a  ftill  more  effectual  coodniiation  of  the  felting,  called  w^rt^ 
ing.  This  is  done  in  another  (bop,  at  an  s^paratus  called  a  batturj^  confifting  of  a  httk 
(containing  water  flighdy  acidulated  with  fulphuric  acid,  to  which,  for  beaver  hats,  a  quand^ 
of  the  grounds  of  beer  is  added,  or  elfe  pjaiii  ws^ter  for  rinfing  out),  and  eight  plankf  of  wood 
joined  tcgjcther  in  die  form  of  a  fruftum  of  a  pyramid,  aii4  meeting  in  the  ketd^  at  the  mid^ 
die.  The  outer  or  upper  edge  of  e^ch  plank  is  about  two  S^  b^oa^  ^  n(es  a  litde.more 
than  two  feet  and  a  half  above  the  gh>und  ;  and  the  flope  towards  die  ketde  is  confiderably 
rapid,  fo  that  die  vidiole  battery  is  little  more  than  (ix  feet  ia  diaaieter.    The^iiandty  of  fuU 


^  For  the  caufct  and  medttaifai  of  felting,  fiu  dit  a9|e  aa  IfkiiM*  J^vnnl,  I.  400* 


phurit 


Report  on  tb^  Manufa^ure  of  Hats.  25 

phuric  acid  added  to  the  liquor  is  not  fufEcient  to  give  a  four  tafte,  but  only  renders  it  rough  to 
the  tongue.  In  this  liquor,  heated  rather  higher  than  unpradifed  hands  could  hcdiX^  the  ar- 
ticle is  dipped  from  time  to  time,  and  then  worked  on  the  planks  with  a  roller,  and  alfo  by 
folding  or  rolling  it  up,  and  opening  it  again ;  in  all  which,  a  certain  degree  of  care  is  at  firft 
neceflary  to  prevent  the  fides  from  felting  together;  of  which,  in  the  more  advanced  ftages  of 
the  operation,  there  is  no  danger.  The  imperfeftions  of  the  work  now  prefent  themfelves  to 
the  eye  of  the  workman,  who  picks  out  knots  and  other  bard  fubftances  with  a  bodkin,  and  adds 
more  felt  upon  all  fuch  parts  as  require  ftrengthening.  This  added  felt  is  patted  down  with 
a  wet  bruih,  and  foon  incorporates  with  the  reft*  The  beaver  is  laid  on  towards  the  conclu- 
fion  of  this  kind  of  working.  I  could  not  diftindly  learn  why  the  beer  grounds  were  ufed 
with  beaver-hats.  Some  workmen  faid  that,  by  rendering  the  liquor  more  tenacious,  the  hat 
was  enabled  to  hold  a  greater  quantity  of  it  for  a  longer  time ;  but  others  laid  that  the  mere 
acid  arid  water  would  not  adhere  to  the  beaver  facing,  but  would  roll  off  immediately  when 
the  article  was  laid  on  the  plank.  It  is  probable  that  the  manufacturers  who  now  follow  the 
eftablifhed  pradiCe,  may  not  have  tried  what  are  the  inconveniences  this  addition  is  calculated 
to  remove. 

The  acid,  no  doubt,  gives  a  roughnefs  to  the  furface  of  the  hair  which  facilitates  the  me- 
chanical adlion  of  felting.  Mr.  Collinfon  informed  me  that  they  ufe  nitrous  acid  in  a  procefs 
called  carrotting.  In  this  operation,  the  material  is  put  into  a  mixture  of  the  nitrous  and  ful- 
phuric  acids  in  water,  and  kept  in  the  digefting  heat  of  a  ftove  all  night.  The  hair  acquires 
a  ruddy  or  yellow  colour,  and  lofes  part  of  its  ftrength.  I  did  not  fee  any  part  of  this  procefs, 
nor  of  the  material  fo  treated;  neither  did  I  gather  any  further  information  refpedting  its  utility, 
than  that,  for  fome  kinds  of  work,  the  carrotted  ftufF  is  better. 

It  muft  be  remembered  that  our  hat  ftill  pofleifes  the  form  of  a  cone,  and  that  the  whole 
of  the  feveral  anions  it  has  undergone,  have  only  converted  it  into  a  foft  flexible  felt,  capable 
of  being  extended,  though  with  fome  difficulty,  in  every  direflion.  The  next  thing  to  be 
done  is  to  give  it  the  form  required  by  the  wearer*  For  this  purpofe,  the  workman  turns  up 
the  edge  or  rim  to  the  depth  of  about  an  inch  and  a  half,  and  then  returns  the  point  back 
again  through  the  centre  or  axis  of  the  cap,  fo  far  as  not  to  take  out  this  fold,  but  to  produce 
another  inner  fold  of  the  fame  depth.  The  point  being  returned  back  again  in  the  fame 
manner,  produces  a  third  fold ;  and  thus  the  workman  proceeds,  until  the  whole  has  acquired 

r 

the  appearance  of  a  flat  circular  piece,  confifting  of  a  number  of  concentric  undulations  or 
folds,  with  the  point  in  the  centre.  This  is  laid  upon  the  plank,  where  the  workman  keep- 
ing the  piece  wet  with  the  liquor,  pulls  out  the  point  with  his  fingers,  and  preflTes  it  down 
with  his  hand,  at  the  fame  time  turning  it  round  on  its  centre  in  conta6l  with  the  plank,  till 
he  has,  by  this  means,  rubbed  out  a  ilat  portion  equal  -to  the  intended  crown  of  the  hat.  In 
the  next  place  he  takes  a  block,  to  the  crown  of  which  he  applies  the  flat  central  portion  of 
the  felt,  and  by  forcing  a  firing  down  the  fides  of  the  block,  he  caufes  the  next  part  to  afTume' 
the  figure  of  the  crown,  which  he  continues  to  wet  and  work,  until  it  has  properly  difpofed 
Itfelf  round  the  block.  The  rim  now.  appears  like  a  flounced  or  puckered  appendage  lound  the 
^ge  of  the  crown;  but  the  block  being  fet  upright  on  the  pbnk,  the  requiiite  figtu'e  is  fbon 
^iven  by  working,  rubbing,  and  extending  this  part  Water  only  is  ufed  in  this  opd^tion  of 
Vol.  III.-— April  1799.  £  fafhioning 


%6  Ripdri  m  the  Mamfaflun  $f  Hats, 

faihioning  or  blocking,  at  the  conclufion  of  which  it  is  preiTed  out  by  the  blunt  edjge  q{  a 
copper  implement  for  that  purpofe. 

Previous  to  the  dying,  the  nap  of  the  hat  is  raifed  or  loofened  out  with  a  wire  bru(b|  or 
carding  inftrument,  as  I  underftood;  but  I  did  not  fee  this  done,  '  The  fibres  are  too  ratten 
after  the  dying  to  bear  this  operation.  The  dying  materials  are  logwood,  and  a  mixture  of 
the  fulphates  of  iron  and  of  copper,  known  in  the  market  by  the  names  of  green  copperas  and 
bine  vitriol.  As  die  time  of  Mr,  Collinfon  was  limited,  and  my  attention  was  moK  particu-* 
larly  directed  to  the  mechanical  procefTes,  I  did  not  go  into  the  dye-boufc,  but  have  no  doubt 
that  the  hats  are  boiled  with  the  logwood,  and  afterwards  immerfed  in  the  (aline  folution.  I  par- 
ticularly a(ked  whether  galls  were  ufed,  and  was  anfwered  in  the  negative.'  From  the  candid 
and  obliging  manner  c^  Mr.  Collinfon,  I  am  convinced  that  his  information  was  corre^  and 
diat  if  he  had  any  fecret  to  referve,  he  would  not  have  hefitated  in  telling  me  So* 

The  dyed  hats  are,  in  the  next  place,  taken  to  the  ftifFening  fbop..  One  vnorkman,  affified 
by  a  boy,  does  this  part  of  the  bufmefs.  He  has  two  veflels,^  or  boilerSy  the  one  containing  the 
>grouilds  of  ftrong  beery  which  cofts  fevenihillings  per  barrel,  and  isy  as  I  prefume,  ufed  in  this 
and  other  ftages  of  the  manufactory,  as  the  cheapeft  mucilage  which  can  be  procured;  and  die 
other  veflel  containing  melted  glue,  a  litde  thinner  than  it  is  ufed  by  carpenters.  I  particularly 
alked  whether  this  laft  folution  contained  any  other  ingredient  befides  glue,  and  was  aflured: 
that  it  did  not.  The  beer  grounds  are  applied  in  the  infide  of  the  crown  to  prevent  the  glue 
from  coming  through  to  the  face,  and  alfo>  as  I  fuppofe,  to  give  the  requifite  firmnefs  at  a  bfs 
expence  than  could  be  produced  by  glue  alone.  If  the  glue  were  to  pais  dirough  the  bat  in 
different  places,  it  might,  1  imagine,  be  more  difficult  to  produce  an  even  glofs  upon  the  face 
in  the  fubfequent  finifbing.  The  glue  ftiffening  is  applied^  after  the  beer  grounds  are  dried^. 
and  then  only  upon  die  lower  face  of  the  flap^  and  the  infide  of  the^crown.  For  this  pur* 
pofe,  the  hat  is  put  into  anodier  hat,  called  a  fliffening  hat,  the  crown  of  which  is  notched)  or 
flit  open  in  various  direSions..  Thefc  are  then  placed  iaa  hole  in  a  deal  board,  which  fup* 
ports  die  flap,  and  the  glue  is  applied  with  a  brufh. 

The  dry  hat,  after  this  operation,  is  very  rigid^  and  its  figure  irregular.  The  kfl  dref- 
iiAg  is  given  by  the  application  of  moifture  and  heat,  and  the  ufe  of  the  brufh,  and  a  hot  iron, 
fomewhat  in  the  fhape  of  that  ufed  by  taylors,  but  fhorter  and  broader  on  the  face.^  The  hat 
being  foftened  by  expofure  to  fteam,  is  drawn  upon  a  block,  to  which  it  is  fecurely  applied  by 
the  former  method  of  forcing  a  firing  down  bom  the  crown  to  die  commencement  of  the  rim. 
The  judgment  of  the  workman  is  employed  in  moiflening,  brufhing,  and  ironing  the  hat,  in 
<}rder  to  give  and  preferve  the  proper  figure^  When  the  rim  of  the  hat  is  not  intended  to  be 
of  an  equal  width  throughout,  I  conclude  that  it  is  cut  by  means  of  a  wooden,  or,  periiaps, 
metallic  pattern ;  but  as  no  fuch  hats  are  now  in  &fhion,  I  (aw  only  the  tool  for  cutting  them 
round.  The  contrivance  is  very  ingenious  and  fimple.  A  number  of  notches  are  made  in 
one  edge  of  a  flat  piece  of  wood  for  the  purpofe  of  inierting  the  point  of  a  knife,  and  ftxxn 
one  fide  or  edge  of  diis  piece  of  wood  there  proceeds  a  ihait  handle,  which  lies  parallel  to 
the  notched  fide,  forming  an  angle  fomewhat  like  that  of  a  carpenter's  fquare.  When  the 
legs  of  this  angle  are  applied  to  the  outfide  of  the  crown,  and  die  board,  lies  flat  on  the  rim 
•f  the  hat,  the  notched  edge  will  lie  nearly  in  the  direftion  of  the  jadiusyior  line  pointing 

to 


On  th$  Manufa^un  dfHats  ly  Michanifm*  tf 

to  flie  centre  of  the  hat,  A  knife  being  therefore  infcrtcd  in  one  of  the  notches,  it  is  cafy  to 
draw  it  round  by  leaning  the  tool  againft  the  crown,  and  it  will  cut  the  border  very  tegular 
and  true.  This  cut  is  made  before  the  hat  is  quite  finilhed,  and  is  not  carried  intirely 
through,  fo  that  one  of  the  laft  operations  confifts  in  tearing  oft'  the  redundant  part,  which  by 
that  means  leaves  an  edging  of  beaver  round  the  external  face  of  the  flap.  When  the  hat  is 
completely  finifhcd,  the  crown  is  tied  up  in  gauze  paper,  which  is  neatly  ironed  down*  It  is 
then  ready  for  the  fubfequent  operations  of  lining,  &c. 

The  art  of  invention,  as  Leibnitz  has  long  ago  remarked,  does  not  conHft  of  lucky  thoughts 
and  intuitive  conceptions,  but  is  a  regular  operation  grounded  on  a  fciencc  which  may  be  - 
taught,  and  of  which  the  rules  are  moft  afluredly  inveftigated  by  every  man  who  after- 
wards fucceeds  in  his  refearchps.  The  inventor  of  commercial  objeAs  ought,  as  I  apprehend^ 
firil  to  afcertain  whether  theprocefs,  he  means  to  improve,  is  capable  of  rewarding  his  exer* 
tions ;  and,  fecondly,  what  may  be  the  phyfical  and  moral  difficulties  that  obfbud  his  purpofe* 
With  a  view  to  thefe  refpedive  departments  of  inquiry,  I  afked  Mr.  CoUinibn  what  he  con-* 
ceived  might  be  the  proportion  of  die  charge  of  raw  materials,  rent,  and  other  expences,  com- 
pared with  that  which  is  applied  to  the  mere  fabrication  of  the  article.  He  feemed  to  think^ 
that  this  laft  might  amount  to  one- third  of  the  whole  coft,  and  that  the  bowing  and  baibning 
might  be  one-fixth.  Now  if  we  take,  as  an  extreme  fuppofition,  that  the  inventor  of  a  machine 
could  accomplifh  the  whole  operation  at  a  charge  altogether  inconfiderable,  and .  that  the 
profits  of  the  manufa^urcr  and  (hopkeeper  may  be  refpedivcly  ao  per  cent,  we  Ihall  find,  by  a 
fimple  calculation,  that  fuch  an  inventor,  if  he  were  to  be  content  with  the  fame  profit,  would 
be  able  to  under-fell  other  hatters  by  about  23  per  cent,  or  if  his  article  were  as  good  or  better 
Aan  theirs,  he  would  have  no  occafion  to  lower  his  price,  but  would  realize  an  extra  profit 
of  28  per  cent  as  a  manu&fhirer.  If  his  machinery  and  working  procefles  were  to  call  for 
half  the  prefent  difburfement,  the  diflierence  would  only  be  1 1^  per  cent  in  the  market ;  and  if 
he  couU  only  do  the  bowing  and  bafoning,  the  (ale  price  would  be  only  affected  to  the  amount 
cf  about  5  per  cent,  or  fix,  confidered  as  manuiafhirers  profit ;  a  diflTerence  fcarcely  more 
than  may  reafonably  be  fuppofed  to  take  place  in  various  manu&Aories,  from  the  miere 
tliflferences  in  (kill  and  diligence  between  one  manufadurer  and  another.  It  may,  therefore, 
become  a  ferious  queftion  (according  to  the  fimplicity,  efficacy,  and  profit  of  a  new  ^an,  which 
may  require  a  manufa£birer  to  interrupt  and  lay  afide  his  old  pra&ices),  whether  he  (hould  not, 
in  prudence)  endeavour  rather  to  improve  die  ftate  of  his  afiairs  by  Ae  fafe  and  ordinary  me- 
thods of  ioduftry,  pun&uality,  and  economy,  than  to  unfettle  his  mind,  and  rifk  his  fortune 
and  tranquillity  in  this  new  purfuit.  And  ftiU  more  will  it  become  a  mere  fpeculattve  mechanic 
eo  confider  how  bx  he  ought  to  purfue  a  fcheme,  for  the  reward  of  which  he  muft  either  enter, 
4noft  probably,  widi  borrowed  capital,  into  a  bufmefs  of  i^ich  he  knows  nodmig,  or  depend  on 
•^knowledge,  the  candour,  and  the  integrity  of  a  manu&durec  for  his  gains,  or  the  i-epoymenl 
4if  bifi  labour  and  expence. 

Thefe  are  the  motives  for  caution  which  ought  certainly  to  prefent  themfelves  in>the  firft 
contemplation  of  an  imdertaking  of  this  kind.    But,  on  the  other  hand,  it  is  too  wdl  kno\im  in 
lis  a^ive  manufa£hiring  country,  that  improvements,  if  made  and  conduced  with  (kill  and  in- 

£  2  tclligence, 


a8  Mechanical  Fabrication  %f  HaH. 

telligence,  are  produAIve  of  wealth,  and  a  "^^x"^  honourable  degree  of  independence  and  public 
eftimation.  In  the  folution  of  a  problem  of  this  kind,  experiments  muft  neceilorily  be  made ; 
and  as  thefe  are  attended  with  expence,  and  require  to  be  frequently  repeated^  in  order  to  avoid 
deception,  the  inventor  will  naturally  be  led  to  inveftigate  and  examine  the  general  ftock  of 
fi£ls,  which>  in  other  branches  of  manufacture,  or  departments  in  natural  philofophy,  may  bear 
any  relation  to  his  own  purfuit.  Hence  it  appears  to  be  of  the  higheft  importance  that  he  (hould 
poflefs  an  extenfive  acquaintance  with  incidents  and  events  of  this  kind.  In  the  purfuit  before 
us,  for  example,  he  (Iiould  learn  all  the  methods  by  which  wool,  fur,  and  vegetable  filaments 
arc  manufa^red.  The  proceffes  of  beating,  bowing,  carding,  felting,  fulling,  fpinning^ 
weaving,  knitting,  and  knotting,  wilt  pafs  in  review  before  him.  He  will  confider  which  may 
bcmoft  applicable  to  his  purpofe,  and  what  new  modifications  or  fucceffive  applications  he  may 
make  of  thefe  refpedive  operations,  of  the  principles  on  which  they  are  founded,  and  of  the 
materials,  as  well  as  the  mechanifm  ufed  for  carrying  them  into  efFeA.  The  certainty  of  thefe 
operations,  which  have  been  pra£Hfed  for  ages,  will  give  ftrength  and  firmnefs  to  his  new 
combinations,  and  if  he  poiTefs  enough  of  this  kind  of  knowledge,  he  will,  probably,  enjoy  the 
fatisfadipn  of  feeing  his  attempts  anfwer  his  expedations,  inftead  of  being  repeatedly  mortified 
and  diftrelTed  by  lofs  of  time  in  alterations.  In  the  prefent  inftance,  on  which  I  have  medi- 
tated but  little,  I  am  unwilling  to  fpeculate  in  the  way  of  conje£lure.  Yet  I  am  inclined  to 
fuggeft  the  enquiry,  whether  carding,  which  is  rapidly  and  mechanically  done,  be  inferior  ta 
bowing,  which  does  not  promiie  much  ^ility  for  mechanical  operation?  Whether  a  fucceffion 
of  batts  or  cardings  might  be  thrown  round  a  fluted  cone,  which  rapidly  revolving,  in  contaA 
with  three  or  more  cylinders,  might  perform  the  hardening,,  and  even  the  working,  with  much 
more  precifion  and  fpeed  than  they  are  now  done  by  hand  ?  Whether  blocking  or  ihaping 
be  not  an  operation  extremely  well  calculated  for  the  operation  of  one  or  more  machines  ? 
Whether  loofe  weaving  and  fubfequent  felting  might  not  produce  a  lighter,  cheaper,  and  ftronger 
article  ?  And  how  far  the  mechanical  lilting,  which  is  not  confined  merely  to  the  hairs  of  ani- 
mals, might  be  applied  to  this  art  \  Thefe,  and  many  other  queftions,  might  be  put  and  illuftrat- 
ed  by  incidents  in  the  private  hiftory  of  manufedlurcs  which  have  come  to  my  knowledge  r  but 
iucb  a  detail  could  not  be  of  any  advantage,  unlcfs  it  were  more  amply  extended  than  the  nature 
of  the  prefent  publication  can  allow. 

The  moral  impediments  to  the  fuccefs  of  inventions,  excluGve  of  thofe  which  vife  from 
co-partner(hips,  arc  principally  fuch  as  may  be  excited  by  rival  manufadurers,  or  may  arife 
from  the  difficulty  of  introducing  an  article  which  muft  pafs  through  many  hands  in  its  pro- 
grcfe  from  the  manufafturer  to  the  pubKc.  The  manufadlurc  of  hats  is,  as  I  underftand,  car- 
ried on  with  capitals  much  differing  in  magnitude^  and  the  manufiidurer  may  either  fell  to 
the  veodery  or  vend  the  article  himfelf,  though  I  do  not  find  that  this  is  ufually  the  cafe.  The 
pofleiTor  of  a  new  invention  for  making  hats  might,  therefore,  ftand  alone  between  the  feller  of 
Ae  raw  material,  and  the  confumer  of  the  finiflied  article,  without  being  neceflarily  dependent 
Qn  a  warchoufe-man  or  retailer.  In  this  refpcft,  therefore,  Ac  purfuit  appears  to  be  liable 
to  no  obje^on» 

« 

YIL 


Difficulties  of  obtaining  a  Miafun  of  Length  from  a  Penduttem  29 


VII. 

j1  popular  Account  of  Experiments  which  have  been  made  or  attempted  for  the  Purpofe  of  obtaining 
an  invariable  Meafure  of  Lengthy  from  the  Difference  between  the  Lengths  of  the  fame  Pen^ 
dulumy  when  adjufted  to  meafure  different  known  Portions  of  Time.  (fV.  N.) 


A 


.BOUT  the  beginning  of  the  prefent  century,  and  for  a  confiderable  time  afterwards,  the 
attention  of  fcientific  men,  namely  Huyghens,  Sir  Chriftopher  Wren,  and  others,  was  directed  ' 
to  the  ufeful  application  of  the  pendulum,  as  an  univerfal  meafure  capable  of  being  obtained  ' 
from  the  menfuratioa  of  time,  by  any  number  of  independent  obfervers,  who  fliould  carefully 
follow  the  fame  procefTes  of  obfervation.     Every  one  knows  that  the  vibrations  of  a  pendulum 
will  be  flower  the  greater  its  length;  and  that  by  the  repeated  meafurement  of  the  fame  portion 
of  time,  the  deviations  from  any  given  fra£lion  of  a  day,  as  for  example  a  fecond,  will  be  (hown 
widi  extreme  accuracy*    Thus  in  the  pendulum  which  fhall  vibrate  feconds,  the  difference  of  ^ 
lefs  than  one-thou(andth  of  an  inch  in  the  length  will  be  (hewn  by  a  variation  of  one  fecond  ' 
per  day;  and  if  the  pendulum,  intended  to  be  ufed  as  a  meafure,  were  adjufted  fo  as  to  keep  ■ 
time  without  varying  one  fecond  in  the  week,  it  {hould  feem  to  follow,  that  our  general  or 
univerfal  meafure  would  be  obtainable  to  lefs  than  the  feven-thoufandth  part  of  an  inch,  or  the 
two  hundred-thoufandth  part  of  the  whole.     But  many  difficulties  prefent  themfelves  upon  a 
nearer  practical  view  of  the  fubjeA.     i.  If  the  expanfion  and  contraftion  from  change  of  tem- 
perature be  not  provided  for,  %re  ftill  have  a  caufe  of  error,  which,  in  a  fteel  rod,  would  amount ' 
to  a  fecond  a  day  for  every  four  degrees  of  the  thermometer*  ;  and  it  fcarcely  can  happen  in  any  * 
common  (ituation,  that  the  thermometer  will'  not  vary  many  degrees  in  the  24  hours.     2. 
The  wheel-work  applied  to  keep  account  and  to  overcome  the  effed  of  the  affiftance  of  the  air 
Will  in  moft)  and,  perhaps,  in  every  cafe  alter  the  meafure  of  the  vibration .  3.  If  the  point  of  fuf- 
penfion  have  any  fpring  or  mobility,  the  vibration  will  be  flower  than  correfpOtids  with  the  ap- 
parent length  of  the  pendulum.  Without  entering  into  minute  deduftions  refpcfting  this  varia- 
tion and  its  quantity,  according  to  different  affumed  laws,  this  effeft  may  be  eafily  (hewn  by- 
hanging  any  weight  to  a  ftring,  and  holding  it  in  the  hand  while  it  vibrates.     The  vibraticm 
will  be  much  quicker  if  the  hand  be  held  ftill,  thin  if  it  be  fuffered  to  follow  the  motion  of  the- 
pendulous  body.     4.  When  a  body  moves  in  a  right  line,  the  whole  of  its  motion  may  be  confi-' 
dered  as  if  it  refided  in  the  centre  of  gravity ;  but  if  it  move  in  a  curve,  one  part  of  the  body  will 
move  fwifter  than  the  other,  and  the  centre  of  motion,  or  place  at  which  an  obftacle  would  ftop  it 
without  occafioning  rotation,  wiU  be  nearer  to  the  outer  fide  of  the  extreme  curve  than  the  centre 
of  gravity  itfelf.  This  centre  in  pendulums  is  called  the  centre  of  ofcillation.  It  is  ufual  in  public 
leSures  to  illuftrate  this  dofirine  by  means  of  a  ftrait  fticlc.  If  the  ftiek  be  held  by  one  end,  and 
the  obferver  ftrikes  an  obftacle  downwards  with  the  middle  or  centre  of  gravity  of  the  ftickj  his 


•  Philof.  Journal,  I.  58 .  • 

Tiand 


/ 


30  J>tfficuhtes  of  Experiments  mth  Pmdulumu 

hand  will  be  jarred  by  a  blow  upwards,  owing  to  the  tendency  of  the  outer  half  of  the  flick  to 
proceed  downwards  by  virtue  of  its  greater  velocity.  If  the  obftacle  be  ftruck  with  the  outer  end 
of  die  ftick,  the  jar  will  be  in  the  contrary  dire£tion,  becaufe  the  whole,  or  the  greateft  part  of  the 
force,  is  exerted  within  the  obftacle;  but  if  the  blow  be  given  at  the  diftance  of  one-third  part  of 
the  outer  extremity,  it  will  be  more  efFedual  than  in  other  cafes,  and  the  greater  velocity  of  the 
external  portion  compenfating  for  the  greater  mafs  of  the  part  neareft  the  hand,  no  blow  will 
be  felt,  becaufe  there  is  no  tendency  to  rotation*  The  ftick  therefore  moves,  and  if  hung  up 
would  vibrate  as  if  its  whole  mafs  were  coUeded  at  the  diftance  of  two-<thirds  of  its  length  from 
the  point  of  fufpenfion.  And  it  is  accordingly  found,  that  a  fmall  ball  hung  by  a  thread  of 
diat  length  will  vibrate  in  equal  times  with  the  ftick.  Mathematician^,  particularly  Huyghens, 
have  determined  the  places  of  the  centres  of  ofcillation  of  bodies^  varioufly  figured  and  fufpend- 
.ed.  It  is  enough  for  our  prefent  purpofe  to  have  (hewn,  that  the  effectual  length  of  a  pendu- 
lum cannot  be  determined  without  admitting  the  ronfideration  of  the  figure  and  magnitude  of 
the  pendulous  body  as  an  element  in  the  procefs  4  or  to  ftate  the  effed  more  immediately,  vra 
:may  obferve,  that  if  two  balls  were  Separately  fufpended,  and  fet  to  vibrate  through  equal 
.arcs,  having  the  diftance  .between  their  centres  and  points  of  fufpenfion  refpeAively  equal, 
the  larger  ball  would  vibrate  flo weft,  becaufe  its  centre  of  ofcillation  would 'be  furtheft  from  its 
centre  of  gravity*  Hence  it  muft  follow,  that  our  two  obfervers,  who  are  fuppofed  to  be  in 
fearch  of  one  and  die  fame  meafure,  would,  independendy  of  the  odier  difficult  requifites,  find 
it  necefiary  to  ufe  balls  either  equal  or  proportioned  to  each  odier  in  a  known  ratio,  a  condition 
which  is  precifely  the  difficulty  this  method  is  meant  to  obviate*  It  will,  moreover^  be  requuredf 
in  order  that  the  determinations  may  hold  good,  that  the  material^  i^edier  metal  or  any  other 
.fubflance,  fhould  be  of  uniform  denfity  throughout,  as  well  as  that  it  (hould  poffefs  great  truth 
of  figure ;  both  vriiich  conditions  fcarcely  require  any  remark  with  regard  to  dieir  pra£lical 
difficulties.  5.  The  force  of  gravitation  is  different  according  to  the  latitude  of  the  place  of  ob- 
fervation,  and  as  far  as  obfervations  have  yet  been  carried,  this  variation  is  not  governed  by  aper- 
fedly  regular  law.  It  is  not  the  fame  in  the  northern  and  fouthern  hemifpheres,  and  is  probably 
afieded  by  the  vicini^  of  mountains,  and  die  pofition  of  die  plane  of  vibration  with  regard  to 
them*  Thefe  caufes,  which  do  not  affed  the  utUity  of  an  inftrument  for  meiafuring  time,  are  of 
great  confequence  in  the  deduction  of  our  linear  meafure*  6.  Whether  there  be  any  notable  ir- 
regularity in  the  rotation  of  the  earth,  from  which  our  meafures  of  time  are  derivied,  ttiay  be 
<)ueftioned*  It  is  probable,  from  the  evidence  of  aftronomical  clocks,  fome  of  which  have  per- 
formed with  wonderful  accuracy,  that  there  is  not ;  and  this  evidence  is  ftill  more  confirmed  by 
the  correfpondence  of  the  rotations  of  Jupiter  and  Mars  widi  refpeft  to  that  of  the  earth,  con- 
cerning which,  I  have  heard  of  no  irregularity,  excepting  in  a  paper  of  Dr*  Herfchel,  in  the 
Philofophical  TranfaSions  for  1784*  7*  The  mechanical  determination  of  the  centre  of  fuf- 
jienfion  is  not  altogether  an  eaiy  ta(k* 

From  thefe,  and,  perhaps,  other  difficulties,  the  admeafurement  of  length  by  the  pendulum 
had  been,  for  a  confideraUe  number  of  years,  difregarded,  when  in  the  year  I774>  thefociety  in 
London,  for  the  encouragement  of  arts,  manu&dures,  and  commerce,  offered  a  reward  of  eme 
hundred  guineas,  for  a  mode  of  afcertaining  invariable  fbndards  for  weights  and  meafures^ 
Gommuoicable  at  all  times  and  to  all  nations,  which  offer  being  continued  for  three  fucceeding 

years* 


,  ♦ 


Tnvinfifn  for  ditaining  a  Standard  Miffure.  31 

years,  v^  nt  k^igth  produ^ve  of  competition  on  the  part  of  five  candidates,  one  of  whom» 

Mr.  John  H^toin)  watcHmaJcer,  of  London,  propofed  in  March,  1779,  to  obtain  a  meafure  b/ 

applying  a  moveable  poiot  of  fu^nfion  to  one  and  the  fame  pendulum,  in  order  to  afcertain 

the  diflfereocje  of  length  between  tw:o  portions  fucceifively  made  to  vibrate,  and  meafure  dif- 

:ferent  koown  parts  of  time.  This  attempt,  whether  from  its  imperfection  in  principle,  or 
the  difficulties  found  by  its  author  in  carrying  it  into  effeA,  was  not  confidered  by  the  Society 
9S  intitkd  to  their  reward ;  but  as  an  encouragement  for  the  fu-ther  profecution  of  the  fubjeCi, 
they  prefenttd  the  initentor  with  thirty  guineas.  After  this  time,  the  purf 'it  remained  unattended 

.  to  for  ii:iWR  years,  till  Mr.Hatton's  plan  was  taken  up  by  the  late  John  Whitehurft,  F.R.S.  an 
iagenious  mechanic  and  worjthy  man,  but  poflfefTed  of  very  little  fcience,  at  whofe  houfe  I  faw 
the  machine  going  in  the  y^ar  1786,  which  he  afterwards  defcribed  in  a  pamphlet  on  that 
exprefs  objeCl*.  He  was,  at  that  time,  of  opinion,  that  bis  pendulum,  which  confifted  of  a. 
ball  of  lead  fufpended  by  the  fine  flatted  fteel  wire,  called  pendulum  wire  (of  which  the  length  . 
was^deiermined  by  im  adjuftable  clip),  would  give  a  meafure  by  the  difference  of  its  lengths,. 
as  before  explaijoed,  which  would  not  be  afteCted  by  the  dimenflons  of  the  weight  itfelf ;  and  his 
weight  was  accordingly  a  very  rude-fafhioned  round  piece  of  metal.    It  was  not  without  fome 

.ilifficulty  that  I  perfuaded  him  to  the  contrary,  which  is  a  point  concerning  which  men  of  in- 

. formation  cannot  have  two  opinions;  but  afterv^ards,  when  he  became  convinced,  he  propofed. 
that  the  bftU  Ihould.  be  made  of  a.diameter  anfwering  to  fome  aliquot  part  of  the  meafure 
expodsd  to  be  obtained,  or  deduced  from  crude  experiments,  and  afterwards  corredied  from, 
ifae  a&ual  refult;  which  correAed  ball  being  ufed  to  obtam  a  fecond  refult,  fhouldbe  agaiiu 
correfied,^  ;md  this  proceis  of  approximation  continued  till  the  refults  were  not  found  to  ^ifier 

;by  jaay  .perceptible  quantity.    I  have  reafon  to  believe,  however,  that  he  never  ufed  this 

.method,  nor  even  took  the  trouble  to  give  any  precifioa  of  figure  to  his  ball,  with  which  be- 

.Viade  the^xperiineints  recorded  in  his  pamphlet*. 
,  After  the  death  of  Mr.  Whitehurft,  his  apparatus  came^  by  purchafe,  into  the  hands  of  Dr.. 

.George  Fordyce,  FJLS.  who  confiderably  improved  it,  and  gave  a  defcription  of. the  fame  to 

;  the  royal  (bcietyf.  The  moft  important  improvement  confifted  in  a  contrivance  to  prevent 
the  efFe&  of  variations. of  temperature  upon  the  pendulum,  which  the  reader  will  perceive  to 
be  highly  valuable  for  the  mechanical  fkill  difplayed  in  the  execution,  and  in  principle  fome- 
wh^t  refembling  the  fixed  apparatus  defcribed  at  page  61  of  our  fir  ft  volume.  As  the  fimili.^ 
tilde  of  the  two  apparatus  of  Whitehurft  and  Fordyce  muft  render  many  particulars  of  the 

/jjefcriptipaof  theAme  in  both,  I  have  given.no  copy  of  the  drawings  of  the  former;  but.fhall* 

'  tjl^Qli  both  copjum^ively. 

Fig*  39  Plate  II,  will  afford  a  more  perfe<9:  notipnof  the  apparatus  than  may,  perhaps^  have 

.\fxxi  conveyed  by  the  verbal  defcriptions  ahready  given.    O  reprefents  the  pendulous  ball  fuf« 

*  An  attempt  towards  obtaining  invariable  meafares  of  length,  capacity,  and  weight,  from  the  menfuration 
of  droe,  independent  of  the  mechanical  operations  requiiite  to  afcertain  the  centre  of  ofcillation,  or  the  true^ 
length  of  pendulums.    By  John  Whitehurft,  F.R.S.  4to.  34  pages,  with  three  plates.    London,  1787. 

t  Accoimi  of  a  new  ^ndulum^  Phil.  Tranf.  1794  ^  from  which  our  drawing  is  copied  of  a  ffflaiUer  fixe,  with 
(bme  amendmenti  of  the  perfpe^ive. 


32  Jppardtus  f.r  ajffhdhg  a  StandofJ  Meatfuu  by  the  Pendulum. 

pcndcd  from  Q^by  the  fine  flat  ft^l  wire  O  N.  In  Mr.  Whitrimrft*s  machine,  the  ball 
'  weighed  12251  grains,  or  upwards  of  two  pounds  troy,  and  the  wire,  whidi  was  flat  ftccl  tem- 
pered^ was  of  futh  a  tbicknefs,  that  80  inches  in  length  weighed  nearlythree  grains.  The  piece 
'  W  I  affords  a  notch  through  which  the  wire  paiTes,  and  which  limits-  the  length  of  the  effeftive 
pendulum.  This  piece  is  fixed  to  the  frame^plate  of  a  train  of  wheels,  fimilar  to  diat  of  an 
eight^y  clock,  which,  by  means  of  a  cruteh  of  communication  applied  to  the  pendulum- 

•  wire,ferves'  to  maintain  the  vibration,  and  keep  account  of  the  time;  The  efcapement  is  the 
dead  beat  of  Graham  *,  with  the  addition  of  an  arm  fpringing  from  the  axis  of  the  pallets  up- 
wards, and  carrying  an  adjuftable  weight;'  the  ufex)f  which  is  to  fet  the  pallets  thcmfelves  to 
the  fame  vibration  as  the  pendulum  is  intended  to  perform  :  a  condition  which  Mr*  White- 

"  hurft,  in  common  vmh  other  aftlfts;  fupp6fed  to  be  of  value  to  prevent  the  maintaining  power 
'  from  influencing  the  meafure  of  time,  though  diis,  in  fad,  depends  more  particularly  on  the 

ftrufture  and  figure  of  the  pallets  f. 
The  principal  fupport  to  which  Mr.  WhitehurfPs  apparatus  was  attached,  confifted  %  of 

two  planks  of  deal,  two  inches  thick,  nine  inches  wide,  and  nearly  fix  feet  long,  which  being 

*  framed  ed^e-Wife  together^  left  a  groove  to  admit  certain  bolts,  or  Aiding  parts,  from  the  move- 
"ment  S  S,  by  (he  help  of  which  it  can  be  raifed  or  lowered,  or  fixed  at  any  defired  elevation. 
In  the  aftual  experiment,  therefore,  the  movement  is  to  be  Aided  up  and  fixed  near  the  top  of 

'  the  frame,  and  the  pendulum  then  adjufted  to  the  longer  vibration  by  means  of  die  fcrew  A, 
which  raifes  or  lowers  the  cock  E  G  N.     This,  in  Mr.  Whitehurft's  proceis,  was  one  foity- 

'  fecond  part  of  a  minute.  There  is  a  brafs  rule  or  piece  5  feet  2  inches  long,  and  one  quarter 
of  an  inch  thick,  fixed  at  its  lower  end  in  one  of  the  planks  in  a  vertical  pofition  to  receive  and 
preferve  the  meafure.    On  dtis  brais  piece,  at  the  temperature  of  60^,  a  fine  ftroke  was  then 

-drawn  by^  means  of  a  proper  tool  applied  againft  the  edge  of  the  plate  of  the  movement.  In 
the  next  place  he  Aided  the  movement  about  five  feet  lower,  and,  by  means  of  a  fcrew  applied  Co 

-  the  bottom  of  the  frame-plate,  the  piece  I  W  was  adjufted  to  the  wire  till  the  vibrations  be- 
came 84  ill' the  minute.  At  this  period,  another  ftroke  was  drawn  as  before  on  the  brafs  rule, 
at'the  (ame- temperature  of  60**,  which  is  fuppofed  to  have  been  kept  up  during  the  whole  of 
the  operation  from  firft  to  laft.   '  This  fuppofition  of  an  equal  or  fteady  temperature  of  the  air 

■  in  an  apartment,  can  hardly  be  admitted,  except  with  regard  to  the  mean  temperature  in  aclofe 
fubterraneous  place,  ^hich  is  mbft  Aeadily  kept  during  fummer,  becaufe  the  warmer  air  from 
above  has  then  no  tendenc}*'  to  defcend. 

Mr.  Whitehurft's  machine  was  fixed  in- the  comer  of  a  firft-floor  room,  in  Bolt-Court, 

Tleet-ftreet,  v^ich,  I  think,  was  wainfcotted.    The  meafure  obtained  as  the  diflrerence  of  the 

two  lengths  aforeiaid,  vibrating  through  femi-arcs  of  3^  20^,  was  599892  §  inches,  and  the 

Sength  of  feconds  pendulum  for  London,  thence  refuldng,  proves  39,1196  inches,  inftead 

» 

*Philof.  Journal,  II.  5*.  +  Ibid,  p.  49,  $0. 

\  Dr.  Fordyce  retained  this  part  in  bis  improved  machine.    Philof.  Tranf.  1794,  p.  16. 

§  Sir  G.  Shuckburgh  Evelyn,  who  afterwards  meafured  it,  found  it  about  0,0013  inches  longer  at  64^9 
-i^luch  if  nearly  equiv&leat  to  the  expanfion  ^  brals  from  6o«  to  640.  Sec  Philof.  Journal  I.  58,  and  Phil. 
Tranf.  1798,  p.  135. 

of 


Apparatus  fir  affording  a  Standard  Meafurt  by  tbi  Pitidulum.  33 

of  the  commonly  fuppofed  mcafure  of  39,2  inches^.  He  thinks  the  (hortnefs  of  his  meafure 
a  proof,  that  the  maintaining  power  did  not  zSt&.  the  pendulum.  But,  on  this  it  may  be  re- 
marked, that  this  power  may  either  accelerate  or  retard  the  time  of  vibration,  according  to  cir- 
cumftances,  and  that  there  were  other  modifying  events  that  would  tend  to  (horten  his  pendu- 
Jum,  fuch  as  the  unfteadinefs  of  his  houfe,  his  flight  frame,  and  the  mode  of  fixing,  as  well  as 
the  loofe  connection  of  the  piece,  I  W,  fig.3,  with  that  frame,  the  extent  of  his  arc,  and  the 
flight  fpring  of  his  wire  at  the  place  of  flexure. 

Notwithftanding  all  the  objeftions  which  may  be  brought  againft  this  method  of  meafuring 
the  difference  of  lengths  of  two  pendulums,  inftead  of  the  diredl  length  of  one,  it  obvioufly 
pofliefles  confiderable  advantages  over  this  laft  method ;  and  though  the  experiment  required 
uncommon  precautions  before  unexceptionable  refults  can  be  ^expeded,  yet,  upon  the  general 
confideration  of  the  limits  of  error  in  a  meafure  obtained  by  this  procefs,  and  that  which  might 
be  had  by  dedudtion  from  the  aftronomical  obfervations' of  angles,  it  appears  more  than  proba- 
ble, that  Hatton*s  procefs  would  prove  the  moft  accurate.  This  was,  no  doubt,  a  leading 
motive  with  Dr.  Fordyce  to  improve  the  machine  of  Whitehurft,  and  is  the  chief  reafon  why 
I  have  thought  it  might  be  acceptable  to  the  reader,  to  pofliefs  an  account  of  fads  whi^h  are 
only  to  be  met  with  in  books  of  confined  circulation. 

One  of  the  moft  confiderable,  if  not  the  greateft  impediment  to  accuracy,  in  Mr.  Whitc- 
hurft*s  experiments,  muft  have  confifted  in  the  variations  of  temperature  to  which  his  apartment 
was  undoubtedly  fubjefted.  Dr.  Fordyce  amended  the  conftrudlion  of  the  clock  fo  far,  that 
thefe  variations  became  of  no  confcquence  during  its  adjuftments  for  time  and  the  fubfequent 
trials  of  rate.  The  wire  N  O,  fig.  3,  muft  lengthen  by  heat  and  contrail  by  cold ;  in  confe- 
quence  of  which,  the  ball  O  muft  rife  and  fall,  and  the  length  of  the  effediive  pendulum  be- 
tween I  and  V  will  be  more  changeable  than  that  of  a  fimple  pendulum.  The  remedy  of 
Dr.  George  Fordyce  was  founded  on  the  confideration,  that  if  the  piece  G  G  were  fupported 
upon  a  metallic  rod  or  other  piece  of  fuch  a  length  as  that  the  expanfion  of  this  piece  upwards^ 
by  any  increafe  of  temperature,  fliould  be  precifely  fuch  as  to  counteract  the  expanfion  of  the 
wire  andpreferve  the  length  of  the  effedive  pendulum  unvaried — the  frame-plate,  S  S,  would, 
when  the  adjuftment  was  completed,  occupy  that  ftation,  i^th  regard  to  the  brafs  bar,  when  at 
60  degrees,  or  any  other  ftandard  temperature,  as  it  would  have  occupied  if  that  temperature 
had  been  permanent  during  the  whole  of  the  adjuftment ;  and,  confequently,  that  the  nuurks 
drawn  on  the  brafs  while  at  that  temperature,  according  to  the  previous  diredions, 
would  not  be  afleded  in  their  truth  from  changes  of  this  kind.  In  fig.  a,  the  mafi 
AAA,  reprefents  the  wooden  fupport  of  the  clock :  P,  reprefents  the  head  of  the  fcrew, 
which  is  denoted  by  the  fame  letter  in  fig.  3.  The  fcrew,  and  confequently  the  piece 
E  G  N  of  fig.  3,  is  fupported  entirely  by  the  extremity  of  the  lever  N  H  P.  This  lever, 
the  unflexibility  of  which  is  fecured  by  the  triangular  framing  M  L  K,  refts  upon  a  brafs 
tube  I  I,  and  is  provided  with  a  counterpoize,  O,  equal  in  weight  to  that  of.  the  pendulum, 
and  ferving  to  (ecure  the  tube  I  I  from  any  ftrain  or  flexure  that  might  arife  firom  the 

t  George  Graham's  numerous  experiments,  loofcly  quoted,  without  reference,  by  Defaguliers,  in  his  Courp 
gf  U3ttre$y  I-  437i  gave  the  meafure  between  391 133  and  39,125  inches  by  comparifon  with  the  fiandard  yardt 
»t  Guildhall  and  at  the  Exchequer. 

Vol.  IIL— April  1799.  F  weight 


34  Appitratus  for  affording  a  Standard  Meafun, 

weight  being  all  cm  one  fide.  The  evident  advantages  of  the  metallic  fupport  1 1  being  made 
in  the  form  of  a  tube  are,  that  it  will  be  more  Vigid  than  the  fame  mafs  any  otherwife  difpofed, 
and  that  it  will  more  fpeedily,  on  account  of  its  furface,  acquire  the  temperature  of  the  furround- 
ing  air.  B  B  is  a  brafs  fupj)ort  to  which  the  tube  C  C  is  firmly  fixed  or  foldered.  This  laft 
tube  is  flit  longitudinally,  and  fits  upon  the  tube  1 1,  fo  as  perfeftly  to  fteady  it,  but,  at  the  fame 
time,  to  leave  it  at  liberty  to  Aide  up  and  down  with  confiderably  fecility.  A  ftrongcr  piece 
E  D  F  furrounds  the  tube  C  C,  and  when  the  thumb-fcrew  G  is  tightened,  it  caufes  C  to 
embrace  I  firmly,  and  confine  it  from  Aiding  at  al!.  Imagine  the  tube  II  to  be  continued 
downwards  ;  and  at  fome  diftance  lower  upon  the  wooden  frame  of  fujjport  there  is  fcrewed  the 
piece  A  D,  fig.  i.  This  piece,  at  its  outer  face,  affords  a  dove-tail  groove  for  a  Aiding  part,  G  G, 
to  move  in.  The  Aiding  part  carries  a  piece  which  forms  two  half  holes  at  K,  which  embrace 
the  tube  1 1,  and  hold  it  firmly  when  the  thumb-fcrews  L  L  are  fcrewed  up :  theadjuftingfcrew 
H  H  is  previou  Ay  ufed  to  fet  the  Aiding  piece  to  any  defired  pofition.  If  we  now  conneft  the 
whole  together,  and  fuppofe  the  tube  I  to  be  grafped  by  the  piece  K  while  it  remains  unconfined 
at  D,  in  fig.  2,  the  whole  pendulum  will  be  raifed  and  lowered  by  the  expanfions  and  contrac- 
tions of  the  tube  I  I,  which  is  above  K.  The  centre  of  fufpenfion  V,  fig.  3,  will  alfo  be  liable 
to  fome  change  of  place  frohri  thermometical  variations  of  the  wooden  frame,  and  the  ball  of 
the  pendulum  will  be  lowered  by  the  expanfion  of  the  fteel-wire  from  the  fame  changes  as 
caufed  them  to  rife  from  the  expanfion  of  the  tube  I  I.  Whatever  may  be  the  metal  of  the 
tube,  it  is  eafy  to  conceive,  that  if  it  be  very  long,  its  efFeft  will  predominate  over  that  of  the 
expanfion  of  the  wire,  and,  on  the  contrary,  that  if  it  be  (horterthan  a  certain  length,  the  con- 
trary tSkA  will  take  place.  That  the  tube  (hall  accurately  compenfate  for  the  changes  in  the 
pendulum  is  a  matter  of  experiment  or  trial ;  and  as  brafs  expands  more  than  moft  other  metals 
in  common  ufe,  it  is  clear,  that  a  (horter  tube  or  brafs  will  anfwer  the  purpofe  better  than  one  cf 
any  of  the  other  common  metals.  To  make  the  adjuftment,  nothing  more  is  required  d>an,  in  the 
firft  place,  to  fcrew  the  tube  faft  by  the  nut  G,  fig.  2,  and  afterwards  loofen  the  piece  K,  fig.  i. 
The  Aiding  piece  G  G  may  then  be  moved  upwards  or  downwards,  by  means  of  the  fcrew 
H  H,  accordingly  as  the  observed  efFeft  of  temperature  upon  the  rate  may  have  indicated  the 
neceflity  of  fhortening  or  lengthening  the  afling  part  of  the  tube.  The  fcrews  L  L,  fig.  i, 
may  then  be  again  fcrewed  up,  and  the  fcrew  G,  fig.  2,  loofened. 

It  is  rather  unfortunate,  that  neither  the  publication  of  Mr-  Whitehurft,  nor  that  of  Dr. 
Fordycc,  contain  any  regifter  of  the  going  of  this  clock.  The  former  had  no  tranfit  inftru- 
ment,  but  carried  his  time  fi'om  his  neighbour,  Mr.  Mudge.  The  latter^  who  had  miAaid  the 
particulars  of  his  obfervations,  kept  his  inftrument  going  at  the  vibration  of  feconds  for  about 
nine  months,  during  which,  the  thermometer  had  fallen  as  low  as  15^  of  Fahrenheit,  and  rifen 
as  highas  84^.  The  grcateft  difference  from  its  rate  of  going  was,  in  the  words  of  the 
Doftor ;  "  Counting  on  according  to  the  rate  of  its  going,  during  the  whole  time,  it  never 
exceeded  the  fum  half  a  fecond,  nor  was  ever  lefs  than  half  a  fecond,  whether  it  was  taken  from 
day  to  day,  month  to  month,  or  from  any  one  to  any  other  period  during  the  obfervation,*' 
which,  I  think,  is  at  leaft  as  accurate,  if  not  more  fo,  than  the  performance  of  any  other  time- 
piece. 

It  is  ftill  more  unfortunate,  that  Sir  George  Shuckburgh  Evelyn,  in  his  late  refearches  to 

afcerOun 


Standard  Miafuri.^^AaUntfthiWingff  a  Ply;  55 

afcertain  a  ftandard  of  weight  and  meafure,  did  not  find  any  wire  which  would  fupport  the 
weight  of  the  pendulum  in  this  machine  during  any  confiderable  period  of  time,  while  it  was  in 
his  poffeiEon  in  1796,  though  he  ufcd  wire  nearly  twice  as  think  as  that  of  Mr.  Whitehurfl*. 
From  this  incident,  I  fliould  have  fufpe&ed  that  Mr.  Whitehurft  himfelf  might  have  annealed 
his  wire  to  a  certain  point,  as  he  (aid  it  was  Umptred^  if  it  did  not  appear  from  a  pafTage  in  Dr. 
Fordyce's  paper,  that  he  himfelf  ufed  it  from  the  bobbin.  For,  he  fajrs,  that  the  curvature  was 
not  entirely  unfolded  for  fome  months,  as  he.  concludes  from  the  clock  having  loft  in  its  rate 
during  that  time. 

Upon  the  whole,  then,  though  the  apparatus  for  making  experiments  with  pendulums  is 
brought  to  a  confiderable  degree  of  perfedion,  yet  it  appears  that  the  fundamental  experiments 
ftill  remain  to  be  made,  in  order  to  afford  a  ftandard  meafure ;  the  old  refiilt  of  Whitehurft 
being  the  only  one  we  are,  at  prefent,  in  poflTeffion  of. 

VIII. 

On  the  Fibration  of  the  Wings  of  a  Fly.    By  S.  R. 

To  Mr.  NICHOLSON. 
SIR, 

X  H  £  conne^lion  of  the  different  departments  of  fcience  with  each  other  is  often  fhewn  in 
rcfearches  where  it  might  leaft  be  fuipeded,  and  it  frequently  happens,  that  fubjeds  of  no  ap« 
parent  or  immediate  utility  may  give  birth  to  refledions  which  afford  an  innocent  and  intereft- . 
ing  fource  of  entertainment,  and  often  lead  to  more  valuable  confequences.  Some  time,  in  the 
courfe  of  laft  fummer,  my  thoughts  were  accidentally  dire(^d  to  the  folution  of  the  problem  of 
'  the  firequency  with  which  flies  and  other  fmall  creatures  move  their  wings.  If  we  were  to 
examine  the  h&s  upon  the  general  principles  of  mechanics,  taking  for  our  data  the  fize  sLOfi 
inclination  of  the  wing,  and  the  velocity  of  flight,  we  fhould  certainly  obtain  a  very  rapid 
feries  of  ftrokes ;  but  there  are  two  other  methods  of  divcSt  experiment,  the  firft  deduced  frofi 
the  doctrine  of  found,  and  the  latter  from  optical  principles,  which  give  an  immediate  refult. 
As  the  number  of  vibrations  performed  by  a  fonorous  body  in  a  fecond,  to  produce  a  given 
note  are  known,  and  no  infe£);  has  any  other  voice  than  that  which  is  afforded  by  the  immedi- 
ate vibration  of  its  wings  or  other  mechanical  action,  we  may  eftimate  the  frequency  of  vibn^- 
tion  in  the  bee,  the  fly,  and  the  gnat,  from  the  refpedive  notes  with  which  their  tones  are  in  * 
unifon.  But,  into  this  enquiry  I  fhall  not  enter,  becaufe  the  other  optical  method  has  aofwered 
my  purpofe. 

M.  D'Arcy  *,  Dr.  Watfonf,and  others,  have  fliewn  that  the  impreflion  of  light  upom  the 
eye  endures  for  a  time  after  the  obje6i  has  ceafed  to  exert  its  adlion,  and  this  truth  is  familiarly 
illuftrated  by  the  common  experiment  of  whirling  the  end  of  a  lighted  ftick ;  the  ignited  extre- 
mity of  which  will  appear  to  form  a  circle,  if  the  motion  be  quick  enough  to  bring  the  end 
round  to  its  firft  place,  before  the  original  impreflion  has  ceafed.  When  a  common  fly  moves 
horizontally  towards  the  fun,  and  the  obfervcr  views  him  in  a  line  at  right  angles  to  his  flighj; 

♦  Memoirs  of  the  Paris  Academy,  1765.  f  On  time. 

F  2  (both 


36  Jcc9unt  of  Farieties  cf  Sulphate  of  Strontlan. 

• 

(both  which  events  are  continually  prcfcntingthcmfelves),  the  ftrokes  of  his  wings  may  be  ob- 
fcrvcd  from  the  reflexions  of  the  light,  which  exhibit  a  row  of  bright  fpccks  or  ftars.  ^Vhen 
the  fly  moves  at  the  rate  of  about  five  feet  per  fecond,  the  intervals  are  about  ten  in  the  inch ; 
but  in  very  quicic  flight,  to  avoid  danger,  he  can  advance  near  three  quarters  of  an  inch  per 
ftfokc.  Now  5  X  12  X  10=600  flirokes  per  fecond,  in  the  fir  ft  cafe.  I  could  not  eftimate 
the  velocity  in  the  fecond  cafe  ;  but  fiippofc  it  might  be  fix  or  fevcn  times  as  much,  or  about 
30  feet  per  fecond*.  No  found  was  produced  in  either  cafe  ;  whence,  I  fuppofe,  the  found 
of  the  wing,  when  the  fly  is  caught,  or  the  fhrill  tone  of  an  gnat  when  it  fticks  itfelf  in  the 
melted  tallow  of  a  candle,  are  produced  by  much  ftronger  and  quicker  adlions. 

If  you  fbould  think  thefe  obfervations  may  be  acceptable  to  your  readers,  they  are  at  your 
fcrvice ;  but  if  not,  excufe  the  trouble  I  give  you,  and  fupprcfs  them. 

I  remain,  Sir, 

Your  obliged  reader, 

S.R. 


IX. 

Jn  Account  rf fever al  Feins  of  Sulphate  of  Strontlan  or  Strontltes^  found  In  the  Neighbourhood 
of  Brijiol^  with  an  Analyfts  of  the  different  Varieties.     By  Willi  AM  Clatfield^^ 


T, 


H  E  firft  fpecimen  of  fulphate  of  ftrontian  was  (hewn  to  me  by  Mr.  Tobin,  about  three 
years  fincc.  At  that  time  it  was  generally  believed  to  be  merely  a  variety  of  fulphate  of  barites* 
It  bad  been  found  at  Redland,  a  fliort  time  before,  in  a  vein  of  confiderable  thicknefs.  The 
greater  part  of  this  vein  has  received  a  red  tinge  from  the  iron  ftone  on  which  it  lies,  and  ex- 
hibits but  flight  traces  of  any  regular  cryftallization.  In  fome  few  fituations,  however,  it  is 
entirely  free  from  colour,  and  appears  to  be  compofed  of  a  confufed  mafs  of  bevilled  tables, 
loofely  adhering  together.  Its  fpecific  gravity  varies  from  3,51,  to  3,87.  Walking  along  the 
beach  at  Auft->paflage,  in  June,  1797,  I  met  With  a  fimilar  fubftance,  and  foon  difcovered 
feverai  detached  veins  in  different  parts  of  the  cliff.  The  ftrata  in  which  theft  veins  are  found 
are  neaHy  horizontal,  confifting  of  limeftoneof  different  degrees  of  hardnefs,  and  argillaceous  fan^* 
ftone,  intermixed  with  clay  and  gypfiim.  The  whole  cliflF,  as  well  as  the  furrounding  country, have 
evidently  been  produced  by  aqueous  depofition,  fince  which  period,  the  level  of  the  water  in  the  main 
channel  having  been  confiderably  lowered,  the  Severn  current  has  acquired  fuflScient  force  to 
deepen  the  bed  of  the  river  by  plowing  up  the  ftrata  which  had  been  previoufly  formed. 

A  fecond  depofition  of  the  foil  towards  the  mouth  of  the  river,  by  forming  diagonal  fifllires 
in  the  cliff,  has  occafioned  an  inequality  of  five  or  fix  feet  in  the  level  of  the  ftrata« 

Thefe  fiffures  are  moftly  filled  up  with  veins  of  ftrontian,  from  three  to  twelve  inches  in 
thicknefs,  confifting  of  an  afiemblage  of  femi-tranfparent  cryftals,  flanked  up  on  each  fide  by  a 
ihin  layer  of  a  fibrous  fraflurc ;  both  of  a  delicately  blue  tinge.     This  laft  variety  was  obferved 

*  A  race-horfe,  at  firft  ftarting,  will  clear  90  feet  per  fecond,  making  about  four,  or,  perhaps,  five  leaps 
^ach  fecond. 

f  From  "  ContrtbutioDS  to  pbyfical  and  medical  Knowledge,  &c.  &c.*'  collected  by  Thomas  Bcddoes>  M.  D. 
^c  the  next  article. 

about 


Jnaljfis  of  Experimnts  Viith  SulphaU  of  Strontiath  He.  37 

about  diree  months  iince,  by  Mr.  Deriabin  (infpe^r  of  the  Ruffian  mines),  who  was  Immedi- 
ately ftruck  with  its  refemblance  to  a  fubftance  of  the  dune  nature  found  in  Penfylvania. 

The  cryftallization  of  the  middle  vein  is  either  that  of  bevilled  tables,  or  rhomboidal  cubes 
of  nearly  an  inch  in  diameter  \  the  tranfparency  of  the  latter  exceeds  that  of  every  other  fpe- 
cies ;  the  fpecific  gravity  of  the  cubes  varied  from  3,88  to  3,96,  while  that  of  the  fibrous  was 
about  3,91. 

Wiihing  to  obtain  fome  muriate  of  barites,  about  nine  months  fmce,  I  reduced  a  portion  of 
thefpar  to  the  ftatc  of  a  fulphure,  anddilTolved  the  earth  in  marine  acid;  the  great  folubility  of 
the  fait,  with  its  needle-formed  cryftals,  foon  indicated  the  prefence  of  ftrontian. 

Several  trials  which  were  then  made  with  it,  fully  confirmed  the  refult  of  the  firft  experi- 
ment. Shortly  after  this,  Dr.  Beddoes  informed  me  of  his  having  met  with  a  paper  of  Klap* 
roth's,  containing  an  analyfis  of  the  American  fulphate. 

Since  the  firft  difcovery  of  this  rare  production,  Mr.  Bright  has  furnifhed  me  with  fpecimens 
of  another  variety  from  the  neighbourhood  of  Ham-green,  where  it  is  found  breaking  through 
die  foil  in  fuch  large  mafles  that  it  has  been  made  ufe  of  in  mending  the  roads.  The  cry- 
ftallization  of  the  latter,  like  that  of  the  Redland,  confifts  of  bevilled  tables;  it  does  not,  how- 
ever, partake  either  of  its  tinge,  or  femi-tranfparency :  its  fpecific  gravity  is  between  3,60 
and  3,68. 

The '  prefent  ftate  of  the  arts  furniflies  continual  inftances  of  the  refufe  of  one  manufa£hire 
forming  the  bafis  of  a  fecond.  While  this  continues  to  take  place,  it  is  evident  that  every 
mere  production  muft  claim  a  full  inveftigation.  The  peculiar  properties  of  this  earth  renders 
it  probable,  that  its  affinities  may  fhortly  be  made  to  furnifli,  us  with  thofe  produ£ltons  from 
the  raw  materials  of  our  own  ifland,  which  we  can  now  only  obtain  with  confiderable  diffi^ 
culty  from  other  countries. 

The  following  analyfis  was  undertaken  at  the  folicitation  of  fome  diemical  friends  ;  more 
leifure  would  doubtlefs  have  contributed  to  greater  accuracy.  What  is  now  ftated  is  tho 
mean  refult  of  feveral  experiments,  the  differences  of  which  have  rarely  amounted  to  more  than 
two  or  three  grains.  Confidering  the  fibrous  variety  as  the  moft  deferving  attention,  it  was 
the  firft  fubjected  to  analyfis. 

To  find  whether  it  contained  any  portion  of  water,  or  other  volatile  material,  500  grains 
were  expofed  to  a  red  heat  under  a  mufile  :  the  lofs,  amounting  to  no  more  than  four  grains, 
proves  than  the  quantity  of  water,  if  any,  muft  have  been  very  trifling. 

1.  200  grains  of  the  powdered  fpar,  in  its  original  ftate,  were  digefted  with  a  folution  of 
carbonate  of  pot-afti  (obtained  by  deflagrating  nitre  and  tartar)  \  the  powder,  when  dried  in  a 
red  heat,  weighed  163,5  grains. 

2.  A  folution  of  this  powder  in  diluted  marine  acid  extricated  47  grains  of  carbonic  acid, 
leaving  about  one  grain  undifTolved :  this  was  afterwards  taken  up  by  the  alternate  application 
of  carbonate  of  pot-a(h  and  marine  acid.  From  this  it  appears  that  the  whole  quantity  of 
earth  muft  have  been  very  nearly  1 16,5  grains. 

3.  The  folution,  No.  2,  was  then  fully  charged  with  cauftic  ammoniacal  gas,  which  pro- 
duced fcarcely  any  traces  of  preci[  itation ;  the  addition  of  carbonate  of  ammonia  immediately 
threw  down  a  precipitate,  which,  dried  as  before,  weighed  nearly  160  grains,  the  difference 


38  Analyfts  and  Experimhts  with  SulphaU  9f  Sirontian^  Ve. 

in  the  weight  of  the  precipitate,  and  that  of  the  i62)5  grains  taken  up  by  the  marine  acldf 
arofe  from  decanting  the  folution  into  diiFerent  veiTels. 

4.  To  dete6l  any  fmall  portion  of  barites  which  might  be  contained  in  the  precipitate,  a 
quantity  of  marine  acid  was  poured  on  it,  fufficient  to  diflblve  only  a  few  grains  of  the  earth. 
Had  any  barites  been  prefent,  it  would  have  been  taken  up  in  preference  to  the  ftrontian, 
from  its  fuperior  affinity  for  the  acid ;  the  folution,  however,  after  digeftion  for  feveral  hours, 
ilill  crydallized  in  needles,  and  afforded  a  copious  precipitate  to  baritic  lime-water. 

5.  164  grains  of  the  precipitated  carbonate  of  ftrontian  were  thrown  into  marine  acid, 
which  extricated,  as  before,  about  47  grains  of  carbonic  acid,  leaving  neasiy  one  grain  undif- 
folved :  the  addition  of  fulphuric  acid  to  the  folution  reproduced  200,8  grains  of  fulphate  of 
ftrontian* 

6.  The  folution  of  pot-afh.  No.  i,  was  then  taken,  and  the  whole  of  the  carbonic  acid  re- 
maining in  it  difengaged  by  an  excefs  of  marine  acid :  the  addition  of  muriate  of  barites 
afforded  a  precipitate,  which,  after  drying  in  a  red  heat,  weighed  nearly  249  grains  :  had  the 
whole  of  the  200  grains  been  decompofcd,  the  folution  would  have  furnilhed  nearly  250  grains 
of  fulphate  of  barites. 

Klaproth  and  Dr.  Withering  having  eftimated  the  quantity  of  fulphuric  acid  contained  in 
artificial  fulphate  at  33,  and  Fourcroy  at  35,  of  the  fpecific  gravity  of  2,24,  or  that  contained  in 
fulphate  of  pot-a(h ;  before  the  concentration  of  the  acid  contained  in  fulphate  of  ftrontian 
could  be  known,  it  was  necefTary  to  make  the  following  experiments : 

7.  218,5  grains  of  artificial  fulphate  of  barites.  were  decompofed  by  digefting  with  a  folu- 
tion of  carbonate  of  pot-a(h,  producing  190  grains  of  carbonate  of  barites,  from  which 
marine  acid  feparated42  grains  of  carbonic  acid,  leaving  nearly  14  j  grains  of  earth  in  folution: 
from  this  experiment  it  appears  that  fulphate  of  barites  contains  about  32,2  per  cent  of  acid. 

To  find  the  concentration  of  this  acid,  124  grains  of  fulphuric  acid  of  1,843  Specific  gravity, 
containing  (according  to  Kirwan's  table,  in  the  Iri(h  Tranfaftions)  109,12  grains  of  ftandard) 
or  97,42  grains  of  2,24,  were  precipitated  by  baritic  lime-water,  producing  283,3  grains  of 
fulphate  of  barites,  containing  nearly  34^4  per  cent  of  acid  of  2,24  fpecific  gravity. 

9.  92,2  grains  of  the  fame  acid  were  precipitated  by  a  folution  of  muriate  of  barites,  the 
fulphate  of  barites  weighed  nearly  212  grains,  containing  about  34,1  per  cent  of  acid  of  2,24. 
By  taking  the  mean  of  thefe  experiments,  we  may  eftimate  the  quantity  of  acid  contained  in 
fulphate  of  barites  at  33  per  cent  of  the  fpecific  gravity  of  2,24. 

According  to  this  calculation,  the  250  grains  of  fulphate  of  barites.  No.  6,  would  furniQi 
82,5  grains  of  acid  of  the  above  ftrength. 

10.  To  afcertain  the  difference  between  native  and  artificial  fulphate  of  ftrontian,  204,2  grains 
of  fulphuric  acrd  of  1,843  (containing  160,44  grains  of  2,24  fpecific  gravity)  were  precipiuted 
by  ftrontian  lime-water,  producing  360  grains  of  fulphate  of  ftrontian,  containing  about  44,5 
per  cent  of  acid.  This  accounts  for  the  200,8  of  fulphate  being  produced  from  163  grainy 
of  carbonate  of  ftrontian,  No.  5.  Hence  the  proportion  of  acid  in  the  artificial  will  exceed  that 
of  the  native  nearly  2  per  cent, 

11.  To  determine  whether  the  folution,  Na  2,  contained  any  calcarequs  earth,  a  fmall 
quantity  of  oxalic  acid  was  added  to  it  i  no  precipitation,  however,  took  place* 

12.  PrufHate 


I 


Analjfit  and  Expirimnfts  with  Sulpbati  of  Stntalan^  (sTc.  3^ 

12.  Pruffiate  of  pot-a(h  occafioned  a  flight  blue  tinge. 

The  difFerent  varieties  containing,  fo  nearly,    an  equal  proportion  of  earth  and  acid,  the 
ft^tement  of  a  fingle  analyfis  will  be  fufficient  for  the  ivhole.     Should  diere  be  any  difference 
between  diefe,  it  will  probably  be  found  in  the  Ham-green  varieties,  containing  rather  more 
acid ;  the  quantity  of  fulphate  of  barites  produced  from  it  amounting  to  nearly  252  grains. 
From  the  foregoing  experiment,  it  appears  that  200  grains  of  the  fibrous  variety  contains : 
Strontian  •         •         .         •         .        •         116,5 

Acid  of  2,24 83,5 

With  a  fmall  proportion  of  iron 


200,0 


In  addition  to  the  modes  of  diftlnguifliing  the  two  earths  already  noticed,  we  may  ftate  the 
cryftallization  of  the  fulphures. 

A  warm  folution  of  the  fulphure  of  barites  depoiits,  on  cooling,  an  aflemblage  of  feve-* 
ral  very  thin  layers  of  inclined  oval  plates,  terminating  in  points,  and  radiating  from  a  centre, 
while  the  fulphure  of  ftrontian  runs  into  a  bafe  line  fu^porting  a  number  of  parallel  perpen- 
diculars, gradually  leflening  fo  as  to  form  the  diagonal  of  a  fquare. 

The  ftrontian  earth  in  a  ftate  of  purity  frequently  varies  in  its  cryftallization,  fometimei 
depofiting  folitary  tables,  and  at  others,  arranging  them  in  irregular  lines.  Both  barites  and 
ftrontian  combine  with  phofphorus,  and  exhibit  familiar  appearances  to  the  phofphure  of  lime. 
Mixed  with  Ks.  grains  of  oxygenated  muriate  of  pot<*afli,  and  triturated  in  a  mortar,  an  exv 
plofion  took  place. 


Note  by  the  Editor.     (Dr.  Beddoes.) 

Mr.  Clayfield  has  lately  been  informed  that  another  variety  offulphate  of  ftrontites  is  found 
near  Sodbury.  Mr.  Deriabin  has  feen  a  blueifti  fibrous  variety,  from  a  coal-pit,  near  Dum- 
barton. On  a  profefEonal  journey  to  the  north,  I  was  ftruck  at  Kefwick  with  a  fpecimen  in 
Mr.  Hutton's  coUedion,  \zhA\tAjiriated  gypfum.  It  is  an  exceedingly  beautiful  white  ful- 
phate of  ftrontian,  from  Alfton,  as  the  label  bears.  From  Mr.  Hutton,  I  have  alfo  received  «■ 
b1uei(h  fpecimen,  cryftallized  in  rhomboidal  tables,  which  I  took  for  fulphate  of  ftrontian ;  b\it 
Mr.  Clayfield  finds  it  to  be  barites.  It  comes  fram  Cleter-moor,  Cumberland.  I  have 
another  from  Newlands,  Cumberland,  having  the  exaft  appearance  of  the  fulphate  of  ftron- 
,  tian  from  Ham-green,  which  requires  further  examination.  Many  fpecimens,  fuppofed  to  be 
baritic,  will  doubtlefs,  On  examination,  prove  to  be  ftrontitic.  But  the  diftinftion  will  re- 
quire nice  infpeftion,  even  from  thofe  moft  verfed  in  the  external  characters  of  foffils. 

The  following  experiments  were  made,  it  my  requeft)  by  a  friend  : — Twelve  grains  of  car- 
bonate of  barites  were  given  to  a  two-months  old  rabbit.  In  half  an  hour  not  much  afFedled 
— <  n  hour  nearly  dead. — The  barites  had  acted  violently  as  a  cathartic,  and  had  produced 
almoft  general  paralyfis^.  In  about  two  hours,  the  rabbit  died  much  convulfed.  The  ftomach 
was  greatly  inflamed  j  the  inner  coat  feparated  from  that  below,  lying  in  folds,  and  as  if  half 

macerated. 


40  Analjfis  and  Experiments  with  Sulpbati  of  Strwttan^  htt. 

macerated.  Five  grains  of  barites  in  a  fecond  experiment,  and  two  in  a  third,  killed  fimilar 
rabbits  with  the  fame  effedl  on  the  ftomach,  only  the  fzces  were  not  fo  much  foftened. 
Forty  grains  of  fulphate  of  barites  had  no  efiie&;  twelve  grairt^  of  carbonate  of  ftrontites, 
obtained  from  the  Briftol  fulphate^  aAed  as  a  cadiartic  only:  of  the  fidphate  itfelf,  twelve 
grains  had  no  efFe£t.  This  feems  to  (how  that  ftrontites  might  be  tried  with  little  riik,  as  4 
medicine,  if  any  analogy  fhould  afford  hope  of  benefit  from  it. 

At  my  further  requeft  the  following  experiments  were  tried.  Five  grains  of  carbonate  of 
l^arites,  mixed  with  &ve  of  Cayenne  pepper,  were  given  to  a  fimilar  rabbit,  which  lived  five 
liours,  and  was  not  much  a(Fe6^ed,  till  within  an  hour  of  its  death,  when  it  fu6Fered  as  in  the 
iirft  experiment,  and  the  (iomach  was  fimilarly  injured.  Conddering  that  fulphate  of  barites 
has  no  aftion,  by  reafon,  probably,  of  its  infolubility,  I  thought  it  poflible,  that  innoxious  ab- 
forbents  might  engage  the  acid  of  the  fiomach,  and  prevent  the  efFefi  of  carbonate  of  barites ; 
ki  which  cafe,  Tinder  certain  circumikmces»  we  (hould  be  provided  with  an. antidote  for  this 
deadly  poifon.  The  following  experiments  (hew  the  conjedlure  to  be  erroneous.  Five 
grains  of  barites,  with  five  grains  of  prepared  pota(fa,  were  given  to  a  rabbit ;  the  aninud 
leemed  immediately  affeded,  in  lefs  than  an  hour  was  fcarce  able  to  move,  and  in  lefs  than  two 
houips  died  convulfed,  with  a  ftomach  extremely  injured,  as  before.  Five  grains  of  carbonate 
of  barites,  with  twenty  of  chalk,  deftroyed  a  rabbit  in  five  hours :  the  animal  died  tranquilly* 
Carbonate  of  barites  five  grains,  with  olive  oil,  killed  a  rabbit  in  lefs  than  two  hours.  The 
animal  having  remained  all  night  unopened,  the  inner  coat  of  the  ftomach  was  fo  much 
loofened,  as  to  (hake  out  with  its  contents*  Happening  to  try  calcareous  liver  of  fulphur  as 
an  antidote,  my  friend  obferved  the  following  phenomena* 

Four  grains  of  carbonate  of  barites,  with  a  teafpoonful  of  a  folution  of  fulphure  of  lime, 
being  given  to  a  rabbit  two  months  old,  the  animal  died  immediately.  The  ftomach  being 
inftantly  examined,  was  found  of  a  dark  colour,  and  at  its  curvature  (qu.  the  great  curva- 
ture?) converted  in  a  yellow  fpongy  fubftance,  which  looked  as  if  burned  by  a  cauftic,  and 
when  removed,  left  bnt  a  very  thin  membrane.  The  contents  of  the  ftomach  near  the  dark- 
ened part,  which  feemed  bounded  by  a  whitifh  line,  were  alfo  dark  coloured.  The  u^W^ 
inner  coat  was  deftroyed.  As  this  rabbit,  two  days  before,  had  been  fubjeded  to  an  expe- 
riment with  fulphate  of  barites,  it  was  neceflary  to  afcertain  whether  this  had  not  fome  (hare 
in  the  unexpected  effed.  A  teafpoonful,  therefore,  of  the  fame  folution  of  calcareous  ful- 
phure was  given  to  a  full  grown  rabbit ;  it  had  the  fame  immediate  efFe£t  in  deftroying  life ; 
and  the  ftate  of  the  ftomach  was  found  to  be  the  fame.  On  the  26th  of  January,  1799,  a 
piece  of  folid  fulphure  of  pot-a(h,  about  the  fize  of  a  pea,  was  given  to  a  rabbit;  and  an  hour 
afterwards,  another  piece  of  the  fame  fize.  A  few  minutes  after  the  firft  dofe,  the  animal 
had  convulfions  of  the  fkin,  which  were  confiderably  increafed  by  the  fecond.  The  whole 
head  then  began  to  fwell,  and  in  two  hours  the  tongue  was  fo  enlarged,  as  to  be  frequently 
bitten  in  attempts  to  mafticate.  In  two  hours  and  a  half,  the  fwelling  was  fo  large,  and  the 
breathing  attended  with  fuch  dlQiculty,  and  croup-like  noife,  that  it  feemed  probable,  the  animal 
had  but  few  minutes  to  live.  The  operator,  heartily  fick  of  thefe  cruel  experiments,  and  un- 
willing to  facrifice  more  viiSims,  gave  the  rabbit  two  teafpoonfuls  of  olive  oil,  and  was  much 
plcafed  to  find  that  in  ten  minutes  it  appeared  much  relieved,  and  that  the  noife  in  refpiration, 

had 


On  the  Difinfiry  tf  Sulpbau  9/  Stnntian  mar  BrtfteT.  41 

hul  cetfed*    The  animal  remtined  very  ftiU,  and  after  oil  had  been  applied  to  the  fwellings, 
was  left  all  night  in  a  baflcet  of  hay,  tn  a  warm  iituation*  ' 

January  27.  The  rabbit  had  left  his  baflcet;;  a  little  warm  milk  was  given  him.  In  the  even- 
ing  he  eat  his  parlley,  and  drank  his  water  heartily.  On  the  evening  of  the  28th^  the  power  of 
the  antidote  being  fuppofed  to  be  afeertaiaed,  the  rabbit  was  killed,  and  a  furgeon  was  defired 
to  ejramine  die.  fwelliilgs.  He  found  that  they  arofe  from  an  enlargement  of  the  maxillary 
glandsy  and  of  the  lymphatiesr  The  ftomacb  waa  covered  with  a  number  of  fmall  fpecks,, 
and  (eemed  a  littfe  ilbftened.  It  (hould  be  obfefved  that  this  rabbit  had  been  kept  on  drr 
food,  which  may  account  for  ^  comparatively  flow  aAioa  of  the  fiilphure.  An  accident  co^ 
firmed  this :  in  die  courfe  of  the  experiment,  having  put  bis  nofe  into  wfiter,  he  received  foi4| 
on  his  tongue,  whidi  being  fwallowed,  greatly  increaled  his  agonies^  Ic  happened  (hortly  be4 
fore  die  oil  was  given*  The  (ulphure  had  been  cat^^Uy  prepared.  The  experiment  with 
die  folution  of  calcareoos  (ulphure  was  twice  repeated :  eadi  dme  the  rabbit  died  in  lefs  than 
two  minutes.    The  flomadi  was  black  and  yellow,  ^ngy,  and  much  corroded. 


I 


X. 

LittirfrAn  Dr.  SaU^esy  rejpg^ing  the  Difcovery  of  SulphaU  rf  Strontian^  announcidat 

Page  535»  AV.  II.  9fthis  Journal 

To  Mr-  NICHOLSON. 
SIR, 


SEND  you  die  Weft-country  contribudons,  ftippoGng  that  it  (alls  within  your  plan  to* 
announce  the  publicadon.  You  will  do  diis  the  more  readily,  as  an  article  in  your  laft 
number  erroneoufly  reprefents  Dr.  Gibbes  as  the  diicoverer  of  the  fiilphate  of  ftrcndan  in 
this  neighbourhood.  This  miftake  you  will  fee  correded  in  a  note*  to  my  table  of  contents. 
Whether  Mr.  Richardfon  told  Dr.  Gibbes  what  he  had  learned  from  Mr.^  Notcutt,  viz.  that 
thefpecinun  he  gave  the  do^or  was  fulphate  ofjirontiany  I  have  not  yet  learned ;  but  I  fuppofe 
he  did,  becaufe  it  is  fo  very  natural  to  do  fo,  in  prefendng  a  ^>ecimen;  and  becaufe  Dr.  Gibbes, 
as  it  appears^  immediately  direi^d  his  experiment  according  to  that  fuppofition.  The  tide  of 
the  paper,  no  doubt  (Difcovery  of  Sulphate  of  Strontian,  near  Sodbury,  by  T.^  S..  Gibbes, 

o  The  note  here  alluded  to  is  as  follows.— At  Dr.  Gibbet  hat  related  an  experiment  of  his  own  on  the  Sod- 
Imry  fulphate  of  ftrontian  in  Mr.  Nicholfon*s  Journal,  MArch,^i799,  without  referring  to  any  other  perfon'a 
preriout  obfervadons,  it  feems  but  juft  to  mention  the  following  circumftancet :  In  the  collection:  of  theRer. 
Mr.  Richardfon,  at  Bath,  a  friend  of  mine  (Mr.  Notcutt),  inftru^d  by  Mr.  W.  Clayfield't  fpecimensy  pointed 
out  fome  fulphate  of  ftrontian.  Mr»  Richardfon  gave  a  piece  to  Dr.  Gibbes,  in  January  lad.  I  had  eiihibited  this 
fubftance,  as  found  in  other  places  near  Briftol,  to  a  large  audience,  nine  montht  before,  viz.  in  Spring,  1798, 
snd  had  fent  fpecimens  to  Mr.  W.  Henry,  who  communicated  the  h€t  to  the  Philofophical  Society,  at  Man* 
chefter.  Dr.  Gibbes  does  not,  undoubtedly,  mean  to  claim  the  difcovery.  He  knew  laft  year  that  Mr. 
Clayfield  was  analyfing  the  fofii!.  Hundreds  of  perfons  might  have  anticipated  Mr.C.  in  announeiog  the  hCt, 
It  is,  indeed,  I  oUerve,  diAinftly  noticed  in  the  Appendix  to  the  Monthly  Review^  vol.  zzv,  p.  580,  June,  1798. 
The  manner  in  which  this  fulphate  was  detected  in  this  neighbourhood  is  exactly  related  below. 

Vol.  IIL~Apbil  1799.  G  M.B.), 


■.-.ir'-' 


4- 


r*\^ 


42  On  Stroniian  and  other  ObjeCls.         . 

Al.  o.),  comfs  from  you*".  The  thing  itfelf  is  of  foiall  importance.  Nobody  thinks  it  of 
]cis  than  the  real  difcoverer  of  the  great  quantities  of  this  mineral,  near  BrifloL  But  unleis 
rightful  claims  are  refpecled  in  matters  of , this  fort,  the  confidence  of  private  communication 
will  be  deftroyed)  than  which  few  events  could  be  more  baneful  to  philofophy*  I  leave  this 
diiagreeable  fubje£t,  with  fincere  regret  that  juftice  could  not  be  done  to  the  parties  by  pri- 
vate explanation. 

The  fecond  edition  of  my  introductory  le6lure  will  (hew  you  that  the  projedfor  giving 
k\t&  le&ures.on  anatomy  and  phyfiology,  to  a  mixed  audience,  fucceeded.  We  have  now 
had  two  fuch  courfes.  I  intend  (if  I  can  find  time)  to  give  an  eactenfive  courlb  of  phjrfiolo* 
gical  ledures,  principally  widi  a  view  to  inftru£l  parents  in  die  means  of  preventing  iickli- 
nefs  and  difeafe. 

Lafl  fpring,  I  publi(hed  a  propo(al  for  inftniding  mechanics  in  the  principles  of  chemiftry. 
But  the  advantage  of  the  fcheme  not  being  fi^lt,  it  was  not  carried  into^execution.  But  Ance 
the  Injiitution  for  diffuftng  Economical  and  Micbanical  Improvements^  has  received  fuch  refpeft  • 
able  bn&xon  in  London,  I  fhould  hope  that  another  attempt  may  fucceed  at  BriftoL 

The  Medical  Pneumatic  Injlitutim  is  open  for  out-patients ;  and  foon  will  be  for  in-patientt* 
I  (hall  immediately  circulate  a  profpeJElus.  I  hope  for  further  fubfcriptions.  Under  the  fuper-^ 
intendance  of  a  young  man  of  fuch  extraordinary  genius,  as  Mr.  Davy,  I  think  we  may  ex- 
peA  ufeful  and  curious  difcoverieaT.' 

I  am,  Sir, 

Your  obedient  Servant, 

THOMAS  BEDDOES. 

Clj/iorTy  March  24,  1799. 

*  In  every  cafe  where  it  has  been  expedient  for  me  to  prefix  a  title  to  the  communications  of  correfpondents, 
I  have  endeavoured,  and  I  hope  with  effect,  to  ihew  that  I  was  the  writer.  In  the  prefent  inftancc,  the  title 
feems  to  be  appropriate  to  the  narration,  which  appears  to  ftate  Dr.  Gtbbes  to  be  the  di(co?erer  what  the  ftito- 
Ibance  was. 


SCIENTIFIC 


o 


RtHificatitn  {f  £th*r.^-N*w  PbtiumtHa  $f  Smind.  43 

SCIENTIFIC  NEPTS  JND  ACCOUNT  OF  BOOKS. 

ReSliJliation  of  Ether. 


NE  principal  objeft  in  the  re<£tification  of  ether^  'is  to  deprive  it  of  the  fulphureous  acid  ; 
for  which  purpofe  the  addition  of  a  re-agent  is  neceflary.  It  has  been  ufual  to  add  an  alkah% 
Dize  has  found  it  much  more  advantageous  to  add  a  fubftaMce  which  might  afford  the  requifitc 
quantity  of  oxygen  to  convert  this  into  the  fulphuric  acid ;  in  which  ftate  it  is  not  difpofed 
to  rife  and  come  over.  Various  metallic  oxydes  were  tried,  among  which  the  black  oxyde  of 
maiiganefe  proved  the  beft  and  die  cheapeft.     His  procefs  is  as  follows : 

The  fulphureous  acid  contained  in  unredtified  ether  being  neutralized  with  oxyde  of  manga- 
nefe,  the  fluid  is  decanted  into  a  pewter  veflfel  of  the  capacity  of  fifty  ounces,  which  is  {daced 
6n  a  water  bath.  To  this  veflS^l  a  head  and  worm  are  adapted,  the  latter  of  which  pafTes 
through  a  refrigeratory  conftandy  fupplied  with  water  in  a  ftream  from  below,  which  caufe» 
die  heated  water  to  flow  ofl^  above.  The  diftillatifttt  is  then  performed  by  raifing  the  bath  to  a 
temperature  of  36^  ( 1 13*^  Fahrenheit  if  the  decimal  thermomctor  be  here  meant) .  The  rec- 
tification by  dirs  treatment  ufiially  requires  a  day  to  complete  it.  The  flavour  of  the  ether  is 
of  the  beft  kind,  ahd  the  produd  about  one-fixtb  more  than  in  the  ufual  method  with  cetort  and 
receiver.    Dize  has  pra£Hfed  this  method  with  fuccefs  for  three  years. 

youmal  de  Phyjique^  ^frik  1798. 


EffeSs  of  the  Gafes  in  producing  Sound  through  a  Pipe. 

ProfessoU  Chladni,  well  known  fer  his  numerous  diicaveries  relating  to  the  theory  of, 
ibund,  engaged  profeflbr  Jacquin,  of  Vienna,  to  make  fome  experiments  on  the  properties  of 
die  difierent  gafes  confidered  as  Ibnorous  bodies,  particularly  thofe  gafes  which  conftitute  our 
atmofphere,  and  ferve  to  produce  vocal  (bunds.     A  glafs  bell  was  furniihed  with  a  metallic 
cork  cemented  to  a  neck  at  the  top ;  and  in  the  bore  of  this  cock,  within  the  glafs^  a  finall  flute 
or  pewter  (etatn)  abo|^t  fix  inches  in  length  was  fixed.   The  gjafs  being  then  placed  on  the  fbelf 
of  the  pneumatic  veffel,  and  filled  with  any  particular  kind  of  gas,  a  bladder  al(b  filled  with  the 
iame  gas,  and  provided  with*a  cock,  was  adapted  to  the  external  aperture  of  the  cock  belongbg, 
to  the  bell*glafs.    In  this  difpofition  of  the  apparatus,  the  flute  was  made  to  found  by  gendy 
preffing  the  bladder.    Comparative  experiments  were  made  with  atmofpheric  gas,  oxygen,  hy* 
drogen,  carbonic  acid,  and  nitrous  gas.     The  inteufity  of  the  found  did  not  vary ;  but  when 
compared  with  that  produced  by  atmofpheric  air,  the  oxygen  gas  gave  a  (bund  half  a  tone 
lower ;   azotic   gas,    prepared   by  diflrerent   methods,  conftantly  gave  a  found   half  a  tone . 
tower  ;  •  hydrogen  gas  gave  nine  or  eleven  tones  higher  ;  carbonic  acid  gas  onc^th jrd  lower, 
and  nitrous  gas  alio  very  nearly  a  third  lower.     A  mixture  of  oxygen  gas  and  azote,  in  the 
proportions  of  the  atmofpheric  atr,  afforded  the  tone  of  this  lafl  y  that  is  to  (ay,  it  was  half  ^ 
tone  higher  than  each  of  the  component  parts  alone.    When  the  two  gafes  were  not  uniformly 
mixed,  the  found  was  abominably  harfli.  Chladni  intends  to  give  a  fuller  account  of  theie  in— 
iprdObing  experiments. 

Journal di  Phxftqury  foLlF^  NS.  p^  57. 

G  a.  CoatrLbutLQiB 


44  Jcaunt  §/ B^i.m^Ur4^iypi  Prinilng. 

Contributions  to  Phyfical  and  Medical  Knowledge,  principally  from  the  Weft  6f  England. 

Collcfted  by  Thomas  Beddoet,  M.D.  odUvo,  539  pages,    Briftol,  printed  for  Longman 

and  Rees,  London. 

I  received  this  work  too  late  in  die  month  to  give  it  that  attentive  perufal  which  is  requifite 
to  enable  me  to  give  an  account  of  its  contents*  The  reader  has  already  feen  an  extrad  in  the 
prefent  number. 


Tables  Portatives  de  l^garithms^  life,  or  Portable  Tables  of  Logarithms ;  containing  the 
logarithms  of  numbers^  from  i  to  loSyOOOi  die  logarithms  of  fines  and  tangents  for  every 
lecond  in  the  firft  five  degrees,  and  for  ^very  ten  feconds  of  the  remaining  degrees  of  die 
^luadrant ;  and  alfo  for  every  ten-thou(andth  part  of  the  axe,  according  to  the  new  centefimal' 
di vifions  of  the  quadrant  (to  feven decimal  places) :  widi  a  preiiminary  diicourfe  on  the  explication, 
.  tife,  and  fiimmation  of  k^arithms,  and  dieir  application  to  aftronomy,  navigationt  prafdcal  geo^ 
metry,  and  the  computation  of  intereft :  to  which  are  added,  a  table  of  logtftic  logarithms^ 
with  other  tables  tA  ufe  for  computii^  the  longitude  at  iea.  By  Francis  Calk^  ftereotype  edi- 
tion ;  engraved,  caft,  and  printed  by  Firmin  Didot,  1795^  in  the  third  republican  year.  Sold 
at  Paris  by  Didot,  price  14  livres,  and  in  London  by  Taylor  and  De  Boffe,  price  i4s. 

In  addition  to  the  accept^le  information  to  men  of  fcience,  diat  a  good  edidoa  of  this  ule- 
fid  work  is  at  prefent  to  be  had,  I  (hall  take  this  opportunity  of  noticing  the  ftereotype  me* 
thod  of  printing,  which  Didot  has  purfued  with  much  ipirit,  and  with  the  advantage,  as  I  un- 
derftand,  of  fupport  from  the  French  government  in  thefe  tables.  The  term  ftereotype  is  de- 
rived from  the  words  ssosog^  ^rmus^  rxmog^  mta ;  doubtlefs  on  account  of  the  immutable  con« 
nedion  between  all  the  parts  of  the  fom  from  whic)i  the  impreffion  is  to  be  given.  I  have 
not  heard  what  may  be  die  peculiarities^ the  method  of  Didot,  for  every  ingenious  man  will 
make  his  improvements  ia  the  art  he  undertakes  to  carry  into  efiefi ;  but  I  fcarcely  need  take 
notice  to  diofe  who  are  acquainted  widi  printing,  that  die  projed  of.  foldering  a  whole  form 
together,  or  of  cafting  a  new  form  from  an  impreffion  made  by  a  general  fyftem  of  types,  or 
page  ready' compofed,  is  not  in  itfelf  new^  Rochon  mentions  *  the  Sall^jft  of  Ged,  under  the 
tide,  C  Crijfi  Saluftii  Catilinarii  V  Jugurtbini  Hijioria^  Edmburgi,  GuilL  Gid^  Jitri  Fabir 
idinenfis  non  ^pis  mobiUbm  ut  vulgo  fieri  JUetyfed  tabeOis  feu  laminis  fufis  exauUbat^  ^7449  f^ 
i6mo.  whidi,  he  fays,  is  well  printed,  and  perfeSly  fimilar  to  a  book  printed  with  moveable 
types.  Didot  now,  it  feems,  follows  the  iame  proceft  as  Ged,  that  is  to  fay,  he  cafts 
plates  from  which  he  afterwards  makes  his  impreffions ;  but  the  logarithms  are  from  Ibldered 
types.  The  advantage  of  Ged*s«Aediod  is,  that  only  a  few  original  types,  comparatively 
fpeaking,  are  neceflary  to  form  die  page,  which  is  to  ferve  as  the  pattern  (or  the  fub* 
fequent  cafts;  that  thefe  cafts  or  plates,  fetting  the  type  at  liberty  to  be  again  ufed  in 
other  works,  may  be  preferved  for  the  purpbfe  of  printing  as  many  impreffions  of  the 
work  as  may  afterwards  be  wanted ;  that  the  rifle  of  any  greater  number  of  impreffions 
than  the  public  may  adually  call  for,  is,  by  this  invention,  done  away,  and  that  even  the 

*  Journal  de  Phyfique,  lY.  Dr.  S.  364.    Sec  alfo  Profeflbr  Wilfon'i  paper  in  Philof.  Journal,  1 1,000. 

^tes 


• 

plates  tbcmfelves  may  become  an  article  of  commerce,  not  only  for  (hop-biflg,  advertifcments, 
and  other  fimilar  articles,  tut  alfo  for  books  of  conftant  £alc  and  invariable  ftruSure,  fuch  as 
mathematrcal  works,  the  claiEcs,  religious  books,  and  the  works  of  celebrated  authors  de- 
ceafed*  How  ^  this  invention  might  be  of  value,  with  regard  to  books  which  arc  altered 
and  improved  in  every  fubfcquent  edition,  may,  perhaps,  be  queftioned  \  but  on  a  loofe  con- 
iideration  of  the  fubjedl,  it  feems  as  if  it  would,  in  every  cafe,  be  advantageous  to  a  bookfellcr 
to  print  a  few  copies  of  a  work,  and  keep  the  prefs  (landing  to  print  others  as  they  may  be 
wanted  ;•— I  fay  it  would  be  advantageous  if  it  were  not  for  the  immenfe  value  in  types,  which 
would,  by  that  means,  be  locked  up.  But  the  ftcreotype  method  has  all  the  advantage  of 
keeping  the  prefs  ftanding,  with  none  of  its  inconveniences,  unlefs  the  weight  and  charge  of 
metal  in  the  plates  ihould  approach  to  that  of  the  types  they  reprefent.  To  form  fome  judg* 
ment  of  this,  it  may  be  ftatcd,  that  the  works  of  Virgil^  printed  by  Didot,  in  i8mo.  which  I 
have  bad  from  De  Boffe,  form  a  beautiful  volume  of  418  pages,  of  35  lines  each.  The  cha- 
xzStcr  ranges  line  for  line  with  that  called  burgeois.  No,  a.  irf  Caflon's  book  of  fpecimens, 
the  jkoc  of  the  letter  being  rather  fmaller ;  and  we  are  told  *  that  the  price  of  the  plates  of  this 
work  is  twelve  hundred- franks,  or  50!.  fterlkig.  From  this  hO:  fon^  judgment  may  bo 
formed  of  the  commercial  queftion,  but  I  am  not  at  prefent  provided  with  the  means  of  mak- 
ing the  ftatemenL 

Befides  the  Virgil  and  the  Logarithms,  Didot  has  printed*,  the  fkbles  of  La  Fontaine,  Cor- 
nelius NepoSy  Ffaaedrus,  the  Vicar  of  Wakefield,  the  works  of  Racine,  5  vols. — of  Boileau, 
3  vols.— of  J.  B.  Roufleau,  2  vols* — and  Lady  Mary  Wortley  Montague's  Letters.  He  is 
now  employed  on  an  edition  of  Voltaire's  works.  All  the  works  here  mentioned  are  of  the 
eighteen  fise,  which,  I  fuppofe,  to  be  better  adapted  to  the  prefent  ftate  of  the  art  than  the 
larger  iizes,  perhaps  from  the  difficulty  of  infuring  perfeS  cafts  in  Che  latter. 


Pnp§fals  fir  ftrmng  by  Suhfcription^  in  thi  Mitrop^lU  ofihi  Britifi  Empire^  a  Public  In/Ktu-- 
timfor  diffiifing  the  Knowledge^  and  facilitating  thi  ggneral  Introduffion  tft^ul  nuchamcal 
InvtnHws  and  Improvements^  and  for  teaching  by  C$urfes  rf  Philofopbical  Le&ures  and  Ex» 
perimentSy  the  jlpplication  of  Science  to  the  common  Purpofes  of  Life^  by  Benj^min^  Count  of 
Rumford^  F.R.S.  M.RJ.J.  iic.  O^avo,  50  Pages.  Sold  by  Cadell  and  Davies  in 
London^  Prite  (uL  ^ 

This  pamphlet  confifts  of  an  introdudion,  followed  by  the  propofak  of  Count  Rumford,  which 
have  been  adopted  by  the  fociety.  In  the  introdudion  he  ftates,  how  flow  the  advancement  of 
ufeful  improvements  has  ever  been,  compared  with  the  rapid  adoption  of  thofe  changes  which 
ibrm  the  obje6l  of  fiifliionable  caprice;  that  the  force  of  habit  operates  in  &vour  of  old  methods; 
that  Bovelty  is  ofFenfive,  and  men  aihamed  to  learn  in  departments  where  they  have  fuppoied 
.  their  knowledge  to  be  complete ;  and  that  the  practical  introdudion  of  new  improvements  is 
rendered  more  difficult  by  the  ignorance  of  workmen  who  continually  blunder,  as  well  as  their 
prefumption  which  leads  them  to  alter  what  they  know  nothing«of.  Hence  he  deduces  the 
great  ut^ity  of  a  general  coUedUon  of  modds  of  things  really  excellent  \  not  only  becaufe  the 

*  La  Decade  Phibfophiqut,  &c.  No.  6.  An.  VIL 

.  .  inftrudlioft 


« 


46  Objeif  and  Regulations  of  the  Injlttutm  for 

infiru£Hon  of  artifts  would  be  die  immediate  confequence,  but  likewife  becaufe  even  the 
moft  powerful  imaginations  would  be  wonderfully  affifted'by  fuch  an  exhibition.  The- 
moral  confequences  are  likewife  adduced  in  favour  of  an  eftablifliment  for  this  purpofe- 
Such  a  reputable  inftitution  would  be  above  the  fufpicions  of  interefted  motives  in  their 
puriuits.  Jealoufy  and  envy,  which  never  foil  to  attack  fuch  aftive  individuals  as  exert 
themfetves  in  difinterefted  projecSts  for  the  public  welfare,  and  in  too  many  inftances  deter 
men  from  laudable  exertions ; — thefe  mean  energies  would  have  lefs  power  to  attack  the 
managers  of  a  public  inftitution,  and  the  managers  themfelves,  on  die  other  hand,  would  have 
the  firmnefs,  the  fpirit,  and  the  power  to  refill  them.  The  obffacles  to  difcovery  are  not 
confined  merely  to  objeds  of  art.  Science  alfo  fufFers  from  the  different  ftation,  habits,  and  mo- 
tives which  give  energy  to  philofophers  and  praSrical  artifb^  The  philofbpher  feeks  fame;  the 
ftanu&£lurer,  profit.  Various  inducements  tend  to  prevent  a  mutual  communication  between 
thefe  clalTes  of  men,  though  both  would  be  highly  benefited  by  a  cordial  intercourfe.  Thejiew 
inftitution  has  this  great  objeA  in  view.  One  circumftance  more  is  mentioned  by  the  Count,  in 
addidon  to  the  foregoing  remarks;  namely,  that  we  are  indifferent  to  iniprovements,  and  think 
them  of  litde  value,  becaufe  our  forefathers  did  very  well  without  them;  and  oh  this  topic  he 
Juftly  remarks,  that  die  argument  is  of  no  value,  fince  it  may  be  brought  in  defence  of  the 
moft  favage  ftate  of  human  exiftence ;  the  only  difFerence  between  this  ftate  and  that  of 
bighefl  culture  and  civilization  being,  that  in  the  latter  a  proper  attention  has  been  paid  to 
mechanical  improvements.  The  introduftory  part  concludes  with  an  hiftorical  (ketch  of  the 
origin  of  the  plan  now  fubmitted  to  the  public,  into  which,  for  the  fake  of  brevity,  I  mud 
forbear  to  enter. 

The  fame  motive  induces  me  confiderably  to  abridge  the  prop^fals,  or  outlines  of  the  plan. 
The  objeft  or  purpofc  of  the  infHtution  is  clearly  exprefled  in  its  title.  In  the  execution  of 
the  plan,  the  firft  ftep  of  the  managers  will  confifl  in  preparing  fpacious^and  airy  rooms,  for 
the  reception  and  public  exhibition  of  all  fuch  new  and  mechanical  inventions  and  improve- 
ments>  as  (hall  be  thought  worthy  of  the  public  notice.  The  models  or  machines  wiH,  as 
much  a5  poffible,  be  of  the  full  fize,  and  exhibited  in  a<^ion  as  in  their  real  applicationv  A 
comi^ete  laboratory  and  philofophical  apparatus  wUl  be  provided  foe  making  experiments;  and 
men  of  the  firft  eminence,  will  be  engaged  as  lecturers. 

The  funds  are  to  be  fupplied  according  to  the^Uowing  conftitutional  reguktionsr  i.  By 
the  fubfcriptions  which  fhall  be  received  from  the  original  founders,  and  fole  proprietors  of  the 
inftitution,  at  50  guineas  each  perfon,  to  be  but  once  paid.  2.  By  the  (urns  contributed  by 
a  fecond  clafs  of  fubfcribers,  at  10  guineas  eadi  perfbn,  tabe  but  once  paid.  3.  By  annual 
fubfcriptions  at  2  guineas  each.  4.  By  donations  and  legacies.  And,  5.  By  fums  received^ 
at  the  door  from  occafional  vifitors. 

The  fubfcribers  at  50  guineas  are  the  proprietors  of  the  inftitutioo,  which  is  to-be  vefted* 
In  them,  their  heirSy  and  aiSgns,  individually;  but.  no  affignment  can  be  valid  till  ratified  by 
the  managers  for  the  time  being.  One  half  of  the  amount  of  their  fubfcriptions  wiH  be  per- 
manently vefted  in  government  ftock,  or  freehold  property,,  and  na  part  of  the  money  will  be 
demanded  of  the  fubfcribets,  nor  any  fteps  taken  for  carrying  the  plan  into  execution,  before 
mcbaiter  fhaU  have  been  pbtaioeJ,,  which.  wiU  effetSlually  defend  the  members  of  the  inliitu^ 


diffujmg  thi  Knnvlidgi  ofujefid  Imprvoiminiu 


47 


lion  from  the  general  confequences  of  co-partnerfliip.  The  proprietors  alone  will  have  the 
t)rivilege  of  voting  for  the  appointment  of  managers  and  vifitors,  and  they  alone  will  be  ca- 
pable of  ferving  in  either  of  thofe  offices.  They  will  have  two  transferable  tickets  of  perpetual 
admiifion  into  every  part  of  the  eftablifhrnent,  and  two  transferable  tickets  of  admiffion  to  all 
the  public  philoibphical  leAures  and  experiments. 

The  iiibfcribers  of  ten  guineas  each  will  receive  one  ticket  of  admiffion  to  every  part  of  the 
inftitution,  and  another  ticket  for  the  public  ledlures  and  experiments.  Thefe  tickets  will  be 
for. life,  but  not  transferable. 

The  annual  fubfcribers  will  alfo  receive  two  tickets  for  the  fame  purpofes,  but  they  will  be 
for  one  year  only,  and  not  transferable.  An  annual  fubfcriber  may  become  a  fubfcriber  for 
life,  by  paying  eight  guineas  at  any  time  before  the  expiration  of  the  year  he  has  fub« 
fcribed  for. 

A  member  of  any  of  the  three  clafles  will  be  entitled  to  copies  or  drawings  of  any  of  the 
models  for  the  ufe  of  themfelves  or  friends,  at  their  own  expence.  The  inftitution  will  be 
governed  by  nine  managers,  chofen  by  ballot  by  the  proprietors  from  their  own  body.  Thefe 
managers  will  receive  no  pay  or  emolument.  They  arc  not  to  difpofe  of  any  of  the  property  in 
premiums.  The  committee  of  vifitors  will  alfo  confift  of  nine  proprietors.  Their  bufmefs  is 
to  infpe£l  and  report  upon  the  flate  of  the  inftitution. 

*  The  lift  of  proprietary  fubfcribers  on  the  7th  day  of  March,  was  as  follows : 


Sir  Robert  Ainflie,  bart. 

J.  J.  Anguftein,  efq. 

Rt.  hon.  fir  Jof.  Banks,  K.B. 

Tho.  Bernard,  efq. 

Scrope  Bernard,  e(q.  M.P. 

The  earl  of  Befborough. 

Rowland  Burdon,  efq.  M.P. 

James  Burton,  efq. 

Timothy  Brent,  efq. 

Henry  Cavcndifti,  efq. 

Rich.  Clark,  efq.  chamb.  of  London. 

Sir  John  Colpoys,  K.B. 

John  Craufurd,  efq. 

The  duke  of  Devonfhire,K.G. 

Andrew  Douglas,  efq. 

The  lord  bifliop  of  Durham. 

The  earl  of  Egremont. 

George  Ellis,  efq.  M.P. 

Jof.  Grote,  efq. 

Sir  Rob.  Batefon  Harvey,  bart. 

Sir  John  Cox  Hippefley,  bart. 

Henry  Hoare,  efq. 

Lord  Hobart. 

Lord  Holland. 

Henry  Hope,  efq. 

Thomas  Hope,  efq. 

Lord  Keith,  K.B. 

Will.  Lufhington,  efq.  M.P. 

Sir  John  Macpherfon,  bart.  M.P. 


WiU.  Manning,  efq.  M.P. 

The  earl  of  Mansfield. 

The  earl  of  Morton,  K.T. 

Lord  Ofllilfton. 

Thomas  Palmer,  efq. 

The  lord  vifcount  Palmerfton,  M.P. 

Edward  Parry,  efq. 

Rt  Hon.  Tho.  Pelhaip,M.P. 

John  Penn,  efq. 

Will.  Morton  Pitt.  efq.  M.P. 

Sir  Ja.  Pulteney,  bart.  M.P. 

Sir  J.  Buchanan  Ridddl,  bare. 

Count  Rumford. 

Sir  J.  Sinclair,  bart.  M.P. 

Lord  Somerville. 

John  Spalding,  efq.  M.P. 

The  earl  Spencer,  K.G. 

Sir  George  Staunton,  bart. 

John  Sullivan,  efq. 

Rich.  Jof.  Sullivan,  efq. 

Lord  Teignmouth. 

John  Thomfon,  efq. 

Samuel  Thornton,  efq.  M.P. 

Henry  Thornton,  efq.  M.P. 

CJeorge  Vanfittart,  efq.  M.P. 

Will.  Wilberforce,  efq.  M.P. 

The  carl  of  Winchilfea. 

I  Ion.  Ja.  Stuart  Wortley,M.P. 

Sir  Will.  Young,  bart.  M.P.  * 


*  The  number  oi  pupsittary  l»iblt:iibcrs  00  the  23d  of  March  kmjunicd  to  feveoty.  eight. 


Th. 


4S  hftituHmfir  Hffufing  ihi  Kmwttigi  rf  Jtnfintkns,  (^e. 

The  prefent  managers  arey 
For  thru  years.  For  two  years.  .  .  For  au,  year^ 

The  carl  Spencer.  The  earl  of  Egreraont  The  earl  of  Morton. 

Count  Rumford.  Rt.  hon«  Sir.  J.  Banks.  The  rt.  horn  Tho.  Pdham. 

Richard  Clark,  efq.  Richard  JoC  Sullivan,  efq.  Tho.  Bernard,. efij.  . 


.    By  a  refolution  of  the  9th  of  March,  Sir  J.  Banks  was  appointed  duurmah  oTalTrac  nixt- 

ings  of  the  managers  which  (hall  be  held  before  a  charter  fhall  have  been  obtained. 

At  the  end  of  this  pamphlet  there  is  a  blank  form  to  be  filled  up  by  thofe  who  intend  to  fub* 
fcribe.  In  this  form,  as  well  as  in  the  body  of  the  pamphlet,  thofe  wlf»  are  deArous  of  be- 
coming proprietors,  are  requefted  to  coniider  themfelves  as  candidates  for  proprietors'  places, 
until  they  (hall  have  been  eleSed  ^%  (iich  by  a  majority  of  the  managers.  But  I  have  flnce 
heard,  that  the  regulation  is,  diat  every  fubfcriber  of  50  guineas,  who  (hall  be  reconimended  by 
a  manager,  will  be  admitted  of  courfe.  Forty  per  cent  of  the  fubfcription-money  will  be  wanted 
immediately,  that  is  to  lay,  after  obtaining  the  cfiarter ;  and  the  remainder  may  be  paid  in 
dsree  equal  balAyearly  payments,  luileis  the  proprietor  (hould  prefer  paying  the  whole  fum  at 
cmce. 


I  am  itauch  ofiligcd  to  Mr.  Sheldrake,  of  the  Strand,  for  his  offer  of  a  drawing  and  defcrip* 
tion  of  a  machine  for  ruling  lines  for  die  ufe  of  engravers,  which  was  con(lru£ied  by  him  ibme 
years  ago:  but  from  his  general  account  of  the  principal  parts,  namely,  a  fteel  rule  and  a 
(crew,  and  a  ratchet  wheel,  as  wide  at  from  the  confined  nature  of  the  objeA,  I  doubt  whe« 
ther  another  engraving  would  be  acceptable  to  the  public,  however  judicious  his  arrangement 
may  have  been* 


r 


- 


yVtUC  LUKAK1 


■^m 


n  nv  TtK 

raiUC  LDRAXT 


a*B 


JOURNAL 


PF 


NATURAL   PHILOSOPHY,   CHEMISTRY, 


AND 


THE   ARTS. 


MAY  1799. 


ARTICLE    I. 
On  the  fhHofopbUal  Vfestf  u  tmmm  Pocket  Watch. — Bj  the  Rev.  IV.  PSAXSW^ 


T, 


H  E  theoretic  philofopher,  who  ranges  through  the  variegated  fields  of  fcicncc,  may  gather 
the  fweets  as  he  palTes  along,  and  gratify  his  tafte  with  fruits  that  he  has  had  no  (hare  in 
rearing,  at  a  very  inconfiderable  expence ;  but  the  pleafure  which  the  pra&ical  man  of  fcience 
derives  from  the  refults  of  his  fuccefsful  experiments  is  much  more  exquifite :  the  previous 
imprelSon  made  by  contemplating  the  harmony  that  appears  in  the  laws  of  nature ;  the  latif- 
fadion  of  proving  the  agreement  or  difcrepancy  between  theory  and  pra£lice;  theprofped  of 
benefiting  fociety  in  fome  (hape,  and,  perhaps,  alfo  the  gratification  of  a  certain  degree  of  vanity, 
all  concur  in  (Simulating  bis  exertions.  If  he  (hould  labour  under  any  inconvenience  in  pro- 
curing the  beft  means  of  profecuting  his  labours,  he  will  naturally  avail  himfelf  of  the  beft 
fubftitutes  diat  the  circumftances  of  his  fituation  will  allow.  From  this  confideration  it 
becomes  a  matter  of  furprize  that  a  niore  general  attention  is  not  paid  to  the  philofophical 
ufes  that  may  be  made  of  a  common  Pocket  Watch.  There  are  many  obfervations  and  ex- 
periments in  diiFerent  departments  of  fcience,  the  accuracy  of  which  depend  greatly,  and  fome 
of  them  entirely,  on  the  accurate  meafurenentof  minuti  portions  of  time ;  fuch,for  inftance, 
as  the  determination  of  the  velocity  of  (bund,  the  nature  of  the  de(cent  of  foiling  bodies,  the 
meaAire  of  the  fun's  diameter,  tlie  diiteooe  of  two  oontigaous,  or  at  Icaft  appar^uly  contiguous. 

Vol.  III. — May  1799.  H  heavenly 


50  Philofophical  Ufes  of  a  cmmdn  Watch. 

heavenly  bodies  taken  at  their  paifTage  over  the  metedian,  and  the  diftance  of  places  from  the 
"difference  of  the  velocity  of  light  and  found.  A  pendulum  to  (wing  feconds  has  ufually  been 
applied  for  thefe  and  fimilar  purpofes,  and  in  an  obiervatory  is  found  to  be  very  convenient  ; 
but  a  watch  by  being  more  portable  is  calculated  to  be  more  general  in  its  application,  and  wilt 
menfure  ftnalkr  portions  of  time  than  any  other  inftniment  that  has  been  invented*  ;  befides, 
it  pofllfTes  this  peculiar  advantage,  that  in  all  fituations  the  biots  thereof  may  be  counted  by 
the  ear,  at  the  fame  time  that  the  objedl  of  obfervation  is  viewed  by  the  eye,  fo  that  no  lofs  is 
incurred,  as  mud  inevitably  happen,  when  the  eye  is  ufed  to  view  both  the  object  and  pen- 
dulum or  fecond-index  in fuccejfion^  though  it  be  ever  fo  quick. — But  it  will  be  objedled  here, 
no  doubt,  that  few  watches  meafure  time  accurately,  and  alfo  that,  from  the  different  conftruc- 
tions  of  watches,  the  timtfs  correfponding  to  their  beats  vary  in  a  very  coniidetable  degree. 
I  allow  thefe  obje£Uons  to  be  true,  and  conceive  that  the  reafon  may  be  attributed  to  them, 
why  the  beatpf  a  watch  is  not  generally  applied  as  the  meafure  of  the  loweft  denomination  of 
fubdivifions  of  time :  I  (hall  therefore  endeavour  in  diis  paper  to  obviate  thefe  objedions,  by 
flic  wing  how  any  tolerably  good  watch,  whatever  be  jts  conftrudtion,  may  be  applied  with  ad- 
vantage to  many  philofophical  purpofcs. 

W«  muft,  in  the  firft  place,  confider  that  the  portions  of  time  which  I  propoic  to  have 
meafured  by  a  watch,  are -^//portions  only,  and  thofe  to  be  counted  not  by  a  fecond-hand,  as 
is  the  cuftom  with  medical  men,  but  altogether  by  the  beats  ;  in  which  cafe,  if  the  watdi  be 
not  liable  to  iofe  or  gain  time  confiderably  in  a  day,  the  error  in  die  rate  of  going  will  be 
extremely  minute  in  the  time  correfponding  to  any  number  of  beats  that  the  memory  can  re- 
tain, or  that  the  purpofes  to  which  I  propofe  the  application  to  be  made  will  require :  and  even 
if  the -error  in  the  rate  of  going  be  confiderable,  fo  as  to  amount  to  many  minutes  in  a*day,as 
it  is  uniform,  it  may  eafily  be  allowed  fof  by  a  corre&ionf .  Hence  the  firft  objeSion,  which  jre- 
lates  to  the  error  occaiioned  by  the  rate  of  going  of  any  watch,  will  confUtute  no  real-obftacle 
to.  its  -application  in  the  afcertaining  of  fmall  portions  of  time,  provided  a  fudden  change  of 
temperature  be  avoided  at  the  time  of  ufing  it;  for  it  will  be  neceflary  that  the  rate  of  going 
be  edimated  when  the  temperature  is  the  (ame,  or  very  nearly  the  fame,  as  when  the  watch  is 
ufed  for  philofophical  purpofes  ;  fo  that  if  it  is  ufually  worn  in  the  pockety  it  may  be  held  in 
the  hand  to  the  ear,  but  if  it  be  hanging  in  a  room  or  in  the  open  air  uriiere  the  rate  of  going 
is  afctfrtained,  it  muft  be  hung  near  the  ear,  under  (imilar  circumftances,  ^ere  any  obferva* 
tion  is  intended  to  be  made  by  it. 

As  to  the  other  objection,  which  appUes  to  the  variation  in  the  lengths  of  the  beats  of  two 
difFerent  watches,  owing  to  the  difFerence  of  their  conftru^ons,  though  they  indicate  hours 
and  minutes  alike,  if  may  be  removed  very  readily.    All  common  watches  have  the  iame  num- 

*  The  bvat  of  a  watch  is  quicker  than  that  of  any  other  chronometer  in  general  ufe  ;  but  there  have  been 
inftnimencs  made  to  divide  the  fecond  into  loo  parts.  One  of  thefe,  made  by  Whitehurft,  and  regulated  by 
a  fly,  repeatedly  meafured  the  time  "tof  fall  of  a  leaden  bullet  (in  fome  experiments  vfhich  I  faw)  with  no 
prater  variation  tbtn  one  hundredth*  part  of  theibcond* — N. 

t  If  the  error  were  five  minutes  per  day,  the  allowance  would  be  lefs  than  one  three-hundredth  part^—N. 

ber 


PhlhfipbictI  Ufa  rf  a  cmmn  fVaicb^  $  i 

ber  of  wheels  and  pinions^  which  are  known  by  this  fame  names,  and  placedy  no  matter  bow 
rarioufly,  fo  as  to  ad  together  without  interruption ;  but  all  watches  have  not  their  corref- 
ponding  wheels  and  pinions  divided  into  die  fiune  number  of  teeth  and  fpaces,  and  to  this 
circunaftance  it  is  entirely  owing  that  the  beats  of  different  watches  differ  from  each  other.  As 
die  rate  of  going  of  a  watch  is  regulated  by  die  lengthening  or  ihortening  of  a  fpring,  without 
any  regard  being  paid  to  the  numbers  ^ich  compofe  the  teeth  of  the  wheels  and  pinions,  a 
great  latitude  is  allowable  in  the  calculation  of  thofe  numbers ;  of  which  the  different  makers 
avail  themfelves  according  as  the  numbers  on  die  engines  they  ufe  for  cutting  the  teeth  re- 
quire: but  whatever  die  numbers  may  be  of  which  die  wheelwork  confifts,  if  we  divide 
double  die  produd  of  all  the  wheels,  from  the  centre  wheel  to  the  crown  wheel  inclulively, 
by  the  product  of  all  the  pinions  with  which  they  a£^  the  quotient  will  be  invariably  the  num- 
ber of  beats  of  die  watch  in  queftion  in  one  hour ;  and  again,  if  we  divide  this  quotient  by 
3600,  the  numbed  of  feconds  in  an  hour,  this  latter  quotient  will  be  the  number  of  beats  ia 
every  fecond,  which  may  be  carried  to  any  number  of  p&ces  in  decimals,  and  be  copied  upon 
the  watch  paper  for  infpedlion  whenever  it  may  be  wanted. 

When  any  particular  watch  is  cleaned,  the  workman  may  be  direded  to  count,  and  return 
in  writing,  the  numbers  of  the  centre  wheel,  the  third  wheel,  the  contrate  wheel,  and  the 
crown  (balance)  yrheel,  and  alfo  of  the  three  pinions  which  they  aduate,  refpedively,  from 
which  the  calculation  of  the  length  of  a  beat  is  eaiily  made  by  the  rule  juft  given,  and  when 
once  made  will  apply  in  all  inftances  where  that  individual  watch  is  ufed.  It  will  be  remarked 
here,  that  no  notice  is  taken  of  the  wheels  and  pinions  which  conftitute  the  dial-work^  nor  yet 
of  the  preat  wheel  and  pinion  with  which  it  ads  :  die  ufe  of  the  former  of  thefe  is  only  to 
make  the  hour  and  minute  hands  revolve  in  their  refpedive  times,  and  nu^y  or  may  not  be  the 
fiune  in  all  watches ;  and  the  ufe  of  the  latter,  the  great  wheel  and  its  pinion,  is  to  determine^ 
in  conjundion  with  the  number  of  fpirals  on  the  fufee,  the  number  of  hours  that  the  watch 
(hall  continue  to  go,  at  one  winding  up  of  the  chain  round  the  barrel  of  the  main  ipring :  all 
diefe  wheels  and  pi^ons  therefore,  it  will  be  perceived,  are  unneceilary  to  be  taken  into  the 
account  in  calculating  the  beats  per  hour.  The  reaibn  why  double  the  produd  of  the  wheels 
fpecified  is  taken  in  die  calculation  is  this,  that  one  tooth  of  the  crown  wheel  completely 
e&apes  the  palats  at  every  two  beats  or  vibrations  of  the  balance.  A  few  examples  vnVL 
render  the  general  rule  porfedly  intelligible*  Let  us  take  for  the  firft  example  the  numbers  of 
a  common  watch  given  by  Mr.  Emerlbn  in  bis  ^*  Tra£k,'*  whidii  according  to  his  mediod  of 
arrangement,  fbnd  thus, 

48  great  wheel, 

I  a— —54  centre  wheel 

-48  third  wheel 

contrate  wheel 

crown  wheel 
a  palats. 

H  7.  Now, 


Ij(m»  omcttingtds6:  great  i«beel:  aad  its.  pinioBk'  of  it^  we  hsre.  54J)C4ft>C^;8^tf$)tl'sl 
3732480.  fbr  double thctpscidti^ of:  the  (pecifie4:whceb>^,a»l  6x6^6 s2 16  far  the  pm^^ 

of  the  fpccified  pinions;  alfd  ^^*;  ^  =  17280  arc  die  number  of  beats  man-hour,  and  •^^if?— 4.11 

%vx.  3600       ^^ 

tbeexad  number  of  beats  per  fecpnd;  aecordin^i  Mn  Emerfon  (ajs  that  this,  watdi  maket* 
*<  about  4|  beats  in  a  fecond."    l^he  number  of  (pcrabofli  the  fufce  is  7  ;.  thereiiare,  7X 

-  ==26  18  the  number^*  hours  that  the  wateh-  wilt  go  at  one  winding  up :  like  wife-die  dia(* 

work  1^ X^^-^=r  12  fhevrs  that  whilft  die  firfl:  driving piniQii.  of  10  goes  twelve  ttmo» 

round,  the  laft  wheel  of  36  goes  only  once ;  whence  die  angular  velocity  of  two  hands  carried 
by  dieir  hollow  axles  are  to  each  other  as  12  to  i. 

For  a  fecond  example,  I  will  take  a  watch  which  is  in  my  own  pofleffion,  the  numbers  of 
which *in the  calculation  of  b^ats  per  fecond  will  be  thus :  60x60x60x13x2= 5616000, 
cbuble  the  prodaS  of  the  wheels;  and'Sx 8x6=384   the  produfi  of  die  pinions;  then 

^''^tf/"^  ^^6*5  wiU  be.  die  beat^  ia  aivh9iir,.  and.  ~^  94^251  diebeata  per  fecond^ 

Befide»  this  I  have  examined  twoother  common  wetche%  one  of  vi^ichrequiresr  this  ad«- 
cttladon :  54  x  51 X  S2X 13  X  2-=  37964i64brdoiibledieprodttA  of  the  wheels,  and6  x  6  x-6^ 

Zi6  ibr  theprodtt^.ofthc  pinions;  tberefoie     ^^^    =17576  arethe  heats  in  an  hour,  and 

^^-  =4^882,  the  beats  per  fecond  by  diis  watch :  alfp  double  the  produA"  of  tke  whecli  oF* 
\  lAeotber,  vi^.  56tX\Si  X  59X^^3  X  x^is  3712800,  and.tfae  produA  of  the  pinions,  as  in  die.. 

laft,6x6x6«s2i6;confeqaeiidy'~~S^^^  17188' beats  in  an*  biMir>  wliidi^«idtfd:'b7t 

3^00  givesN497746  for  the  beats  per  fecond. 

Thefe  four  examples,  it  is  prefumod,  mil  render  die  method  of  afirertaining  the  beats  p^ 

fccoodinany.wiaichfufficiendy  eafy  for  any  per(bn  who  is  acquainted.with  common  arithmetic. 

.  It  remain&now  for  an  inftanccor  two  to  be  adduced  for*the,  application  of  the  beats  of  a 

watch  to  pbilafopliical  purpoles>  ia  order  to  (hew  the  practical  utility  of  die  method  here 

pi^qiofiaiof  meafuring  veiy.finaU  portions  of  time. 

Let  us fnppofep  for ondinftanoe,  with  Dr.  Herfchel,  that  the  annual  parallax  of  die  fixed 
ftars  may  be  afcertained  by  obferving  how  dio  angle  between  two  ftars,  very  near  to  each 
other,  varies  in  oppofite  parts  of  the  year.  For  the  purpofe  of  determining  an  angle  of  this  kind, 
where  an  accurate.micrometer  is  wanting,  let  a  tdefcope  that  has  crob-wiresbedireded  to  the 
ftars  when  paffing  die  meridian,  in  fuch  a  manner  that  die  upright  wire  nay  be  perpendicular 
to  the  horizon,  and  let  it  remain  unmoved  as  foon  as  the  former  of  the  two  ftars  is  juft  com* 
ing  info  the  fidd  of  view,;  dien  fixing  die  eye*  to  the  tdefcope  and'the'viratch  to  the  ear,  repeat 
the  word  om  along  with  every  beat  of  the  watch  Before  the  ftinr  is  arrived  at  the  perpendicular 
hair,  until  it  is  inconjunAion  with  it,  from  which  beat  go  on  two^  thne^  fiur^  &c.  putting 
^wiu  finger  of  ekhtr  hand  at  every  iwtntf  tiU  die  fecond  ftar  is  feen  in  the  iame  fituation 

diat 


PhiJrfopbkidlJfestf  a  cmmnWmth.  53 

that  the  leading  one  occupied  at  the  commencement  of  the  counting ;  then  thefe  beats  divided 
by  the  beats  per  fecodd  marked  on  the  watch-paper,  will  give  the  txiQt  number  6f  uncor- 
rected feconds,  by  which  the  following  ftar  pafles  later  over  the  meridian  than  the  leading  one  : 
^en  thefe  feconds  and  parts  of  a  fecond  are  a(certained,  we  have  the  following  analogy 
fordetermining  the  angle,  which  includes  alfo  the  corredion,  namely,  as  the  time  of  a  fidereat 
rotation  of  theeaith  (which  at  a  mean  rate^  may  be  taken  at  23h.  56'  4^^098,  but  more  or  lefs 
accordingly  as  the  earth  is  near  the  aphelion  or  perihelion  of  its  orbit)|  the  daily  error  in  the 
rate  of  going,  is  to  360S  ^o  is  the  obferved  mraiber  of  feconds  (of  time)  to  the  quantity  of 
the  required  angles.  The  watch  is  here  fuppofed  tobe  regulate  to  (hew  folar  time;  but  if 
it  fhould  be  regvlated  -e^cadly  for  iidereal  time,  inftead  of  23h.  56'  4^098  we  muft  ufe  exadly 
24  hours  in  the  analogy. 

As  a  fecond  inftance,  let  it  be  required  to  afcertain  the  diftance  of  the  nearer  of  two  eleAri^ 
fied  clouds  from  an  obferver,  when  there  are  fucceffive  peals  of  tbunder  to  be  heard :  a  little 
time  before  the  expefted  repetition  of  a  flafh  of  lightning  place  the  watch  at  the  ear,  and  com- 
tnence  the  numbering  of  the  beats  at  the  inftant  die  flafli  is  feen,  as  before  direfted,  and  take 
care  to  ceafe  with  the  beginning  of  the  report  %  then  the  beats  converted  into  feconds,  with 
die  proportional  part  of  the  daily  error  added  or  fubtrafied,  will  give  the  difference  of  time 
taken  up  by  the  modon  of  the  light  and  (bund :  if,  iaftly,  we  fuppofe  light  to  be  inftantaneous  at 
lihall  diftances,  the  diftance  of  the  nearer  cloud  will  be  had  by  multiplying  the  diftance  that 
ifbund  is  khown  to  pals  through  in  a  fecond  by  the  number  of  obferved  feconds  obtained  from 
the  beats  diat  were  counted. 

Many  more  inftances  might  be  here  pointed  out,  in  which  the  beats  of  a  good  watch  would 
l>e  extremely  (erviceable  in  the  praAiod  branches  of  philofophy ;  but  the  oitcurrence  of  fuch 
in&aces  will  always  point  out  the  propriety  of  the  applicadon,  when  it.  is  once  known  agd 

I  fhali  dierefore  only  mention  one  furdier  advantage  which  feems  peculiar  to  this  mode 
tf  counting  a  limited  number  of  feconds  by  a  watch,  which  is,  that  it  is  free  from^any  error 
thatmigjit  arile  from  the  graduatbns  of  a  dial-plate,  or  unequal  divifions  in  the  teeth  of  wheels 
^tfid  pinions,  where  the  feconds  are  counted  by  a  hand. 

*  Iniordfir:  U^f  introduce ^his  method  of  meafuring  fnnll  portions  of  dme^  accurately,  it  is  de- 
firable  that  m  witch  be  conftrufiied  lb  as  to  make  an  exa£l  number  of  beats  p^  fecond 
without  a  frafiion,  far  dien  the  redudion  of  beats  into  feconds  would  be  more  readily  madew 
IVidi  a  view  of  t  promoting,  thisobjed,  I  have  calcuhited  numbers  for-  a  watch,  which  will 
l^uce  die  defired  eflS^d,  and  which,  as  they  are  equally  pradicable  as  thefe  in  ufe,  I  (hail 
infert  in  diis  paper,  in.  hopes^of  hearing  at  fome  future  period,  that  they  ^have  been  adopted 
by  fome  gfxxl  workman;  By  the-  method  o£  arrangement  already  given,  the  numbers  proper 
for  fuch  a  watch,,  as  will  indicate  hours^  minutes,  and  feconds,  by  three  hahds^  and  alfemake 
juft  four  beats  per  fecond^  will  ftanddius,  vie 

"*  I  am  not  aware  of  any  obfervoble  variation  in  the  time  of  the  earth's  rotation,    ft)  theory  it  may  vary  from 

th^TariBbit  difturbiog  foroet  of  fun  and  moon,  as  well  as-from  Mher  caufes  >vhich  may  affe6i  it$  mean  diameter. 

asePluM:  Journal,  1. 19$.^!.  4«^aod  III.  3o.«*^N. 

50  great 


t .  I 


54  Pbikfiphical  Ufa  tf  a  commm  fVaUb, 

m 

50  great  wheel 

ic        6a  centre  wliccl 

8  ■   ■  64  third  wheel 

8        48  contrate  wheel 

6      ■  15  crown  wheel  ^ 

2  pivots. 
DiaI*work  as  ufual. 

Six  fpirals  on  the  barrel— to  go  30  hours. 
By  the  preceding  general  rule  for  afcertaining  the  beats  per  fecond  in  any  watch,  the  cai* 
culation  of  thefc  numbers  will  be  thu3 :  60  X  64  X  48  X  1 5  X  2 = 5529600,  and  8  X  8  X  6 = 384 1 

then  — — —  =:  14400,  the  beats  in  an  hour,  and  ^=4  exactly,  for  the  beats  per  fecond  ; 

which  agreement  with  the  rule  is  a  proof  of  the  accuracy  of  the  numbers. 

Whilft  [  am  upon  this  fubje£l,  I  (hall  take  the  liberty  of  cautioning  medical  gentlemen 
tgainft  an  impofition  which  fomc,  I  hope  not  many,  watchmakers  pradife  towards  them  in 
the  fale  of  watches ;  and  I  the  more  readily  make  this  caution  public,  becaufe  the  health  of ' 
thoufands  of  individuals  is  connected  with  the  impolltion,  which  is  this,  that  a  fecond-hand, 
with  a  ftop,  and  an  appropriate  face,  are  fometimes  put  to  a  watch,  the  wheelwork  of  which 
is  not  calculated  to  indicate  feconds.  The  watch  which  is  the  fecond  mentioned  in  this  paper 
as  being  in  my  own  pofleffion,  is  one  of  this  kind  ;  I  bought  it  of  a  clock-maker,  who  had 
it  made  in  town,  with  his  own  name  enamelled  on  the  &ce,  but  unfortunately  I  kept  it  too 
long  before  its  imperfedion  was  difcovered,  fo  that  I  am  now  under  the  neceility  of  uling 
it*  Upon  enquiry,  I  found  that  more  of  the  iame  kind  have  been  fold  to  medical  gentlemen 
and  others  for  the  purpofe  of  afcertaining  the  number  of  pullations  of  invalids  in  a  minute, 
in  order  that  they  may  be  treated  accordingly.  At  firft  I  fufpe£led  that  the  difagreement  in 
the  motions  of  the  fecond  and  minute  hands,  which  I  obferved^  might  be  owing  to  fome 
iiiequality,  or  (hake,  as  the  workmen  call  it,  in  the  teeth  and  fpaces  of  die  wheelwork ;  but 
upon  counting  the  numbers  1  afterwards  dete£led  the  real  caufe ;  that  part  of  the  train  which 
lies  between  the  axle  of  the  centre  wheel  and  the  axle  of  the  contrate  wheel,  on  which  the 

hands  are  placed,  viz.  '^X  ^  is  equal  to  only  56,25  inftead  of  *6o,  fo  that  3^  feconds  are 

in  dtfcSt  in  every  minute,  which  is  equal  to  a  whole  revolution  of  the  fecond-hand  in  every 
16  minutes :  hence,  if  the  pulfations  of  any  patient  in  a  fever  were  really  120  in  a  minute, 
the  determination  by  the  fecond-hand  of  die  watch  in  quefHon  would  be  only  i  J2|,  conie- 
quently  the  judgment  of  the  phyfician  or  apothecary  would  be  proportionably  biaiTed  in  draw- 
ing a  condufion  from  die  pulfe  upon  die  (bte  of  the  fever,  and  would  undoubtedly  prefcribe 
medicines  accordingly.  It  is  to  be  hoped,  therefore,  diat  the  obfervations  here  made  upon 
the  conftruAion  of  a  watch  may,  exelufively  of  philofophical  purpofes,  prove  ufeful  in  di- 
reding  the  choice  of  fuch  gendemen  as  may  have  occafion  to  purchafe  a  ftop->watd),  and  confe* 

*  If  a  wheel  of  #4  be  fabftinned  for  either  of  thofe  of  60  etcb,  thci  fccondt  will  be  truly  indicated.— P. 

quendy 


Phihfopbicdl  and  Chemical  Informaim.  ^^ 

^uendjr  tmy  obviate  the  deception  which  has  hitherto  been  praftifed  by  certain  makers  and 
venders  of  watches. 

Lincoln^  jfpril  5thy  1799* 


Litttr  from  Mr.  H.  DAVTy  introduHory  to  the  Experiments  contained  in  the  fuhfequent  Article^ 

and  on  other  Suhje^s  relative  to  the  Progrefs  of  Science. 


I 


SIR, 


SEND  you  for  your  PhyGcal  Journal,  experiments  and  obfervations  on  the  ilint  contained  in 
tile  epidermis  and  other  parts  of  certain  vegetables :  thefe  experiments  have  been  made  widiin 
die  laft  fortnight.  I  am  induced  to  make  them  public  fo  (peedily,  from  the  hopes  that  others, 
who  have  greater  opportunities  and  more  leifure,  may  be  ftimulated  to  further  refearches  on 
this  interefting  fubjed.  I  doubt  not  that  other  plants  will  be  found  to  contain  filex,  as  well, 
as  the  reeds,  the  canes,  and  the  gralTes. 

In  the  Pneumatic  Inftitution  we  have  lately  made  fome  experiments  on  die  nitrous  phofoxyd 
(gaieous  oxyd  of  azote)^  the  principle  of  contagion  of  Mitchill.  When  it  is  mingled  with 
^of  phofoxygen  (oxygen  gas),  animals  live  in  it  without  fuilering  any  injury.  I  have  made 
two  infpirations  of  it  pure,  without  any  difagrceable  efFedts.  I  have  breathed  it  mingled  with 
an  equal  quantity  of  phofoxygen  (oxygen  gas)  for  fome  minutes  ;  the  effects  produced  by  it 
were  vtiy  peculiar:  (hould  they  be  confirmed  by  future  experiments,  it  will  probably  prove  a 
valuable  medicine. 

Ia  my  eflay  on  heat,  light,  &c.  in  die  W^ft-country  Contributions,  p.  loi.  ob.  4,  ao  inac- 
curacy occurs  with  refpedt  to  the  production  of  diis  gas.  '  It  is  (aid^^no  light  is  produced 
'^during  the  decompofition  of  phofnitrate  of  ammoniac  by  heat."  In  the  experiments  from  which 
that  ob&rvation  was  deduced,  no  luminous  appearance  was  vifible,  as  tht  phofnitrate  was 
mingled  with  a  large  quantity  of  filiccous  (and,  and  (lowly  decompofed  by  the  heat  of  an  Argand 
lamp.  Lately  I  have  made  the  experiment  in  the  large  way :  when  the  heat  is  quickly  ap« 
plied  and  the  phofiiitrate  mingled  with  but  a  fmall  quantity  of  land,  a  vivid  luminous  ap«. 
pearance  is  uniformly  perceived.  A  paper  on  the  nitrous  .phofoxyd  will  appear  in  the  next 
volume  of  Dr.  Bcddoes*^  contributions. 

With  the  hopes  of  difeovering  a  cheap  fubftitute.for  nitre,  I  have  lately  made  the  pbofiau* 
riafes  (oxjrgenated  muriates)  of  ftrontian  and  barytes.  The.properties  of  the  firfticorrefpond  with 
the  iGpount  I  have  given  of  them,  in, the  Weft-country  Contributions,  arL  Combinationiof  the 
muriatic  Pholacid,  except  that  its  folubility  is  not  fo  great  as  I  at  firft  fufpeAed.  The  pboT- 
UHiriate  of  barytes  cryftaliiles  in  plates,  and  detonate^  veiy  Highdy  widi  charcoal  and  phof- . 
phorus.  A  folution  of  it  in  water,  like  diat  of  the  phofmuriate  of  ftrontiai^  becomes  lumi- 
nous when  the  Xulphuric  acid  is  poured  into  it. 

I  woqM  wifh  to  obferve,  that  no  aiFedlation  of  Angularity  induces  me  to  uf^  a  new  nomen- . 
claturt.    Theory  or  arrangement  of  fa£ts  depends  altogether  on  langua^ge,  i.  e.  in  applying 

certain 


certaui  ^eaeral  4orin€  to  ^  number  of  fiinilar  ideas,  or  fitnilar  tcaios  af  ideas ;  cotAopmaldf 
ibere  cannot  well  be  a  new  theory  without  a  new  nomenclature.  Till  my  experioients  lOD 
heat  and  light  are  rendered  incoticluiivei  by  numerous  contradi£kory  &^  or  experiments,  I 
connder  myfelf  as  entitled  to  ufe  my  prefent  nomenclature  for  the  combinations  of  light. 

Dr*  BcddOes  defires  me  to  inform  yoii,  that  the  Pneumatic  Inftitution,  lb  £u:  as  we  can  yet 
judge,  promifes  to  do  well.  We  were  apprehenfive  that  prejudice  would  prevent  applications  ^ 
but  no  fooner  was  its  opening  notified  to  the  people,  than  they  began  to  rcfort  to  it.  We  have 
already  upwards  of  fifty  patients.  By  degrees  we  {halt  provide  apparatus  for  trying,  in  every 
way,  fuch  gafes  or  vapours  as  promife  any  thing,  or  ought  to  be  tried.  He  requefts  furdiei^ 
that  you  would  notify  tliat  a  confiderable  prror  has  been  difooverisd  in  the  copy  frpm  wUch 
page  381,  line  9,  of  the  "  Weft^cpuntry  Contributions''  was  printed:  it  Xhould  .be 
<<  calomel,  three  grains,''  inftead  of  ^  calomel,  eight  grains.''  I  remain^  Siti  with  wiflies> 
for  the  fuccefs  of  your  academical  undertaking, 

Yoursy  wUhgneatfttTpe^ 

Cliff  n,  AprU  i  uh>  HUMJfMXT  DaTT. 

y   .  To  Mr.  Nicho^-son. 


III. 

EiepirtMUHti  snd  Obfirvatlom  §n  the  Silex  compojing  the  Epidermis^  or  external  Sart^  emieeit- 
tained  in  other  Parts  of  certain  Vegetables.     By  HuM^HItr  Davt. 


D.  1.  A. 


FEW  day^  ago,  Mr.  Coatcs,  of  Clifton,  informed  me  that  his  fon,  accidentally 
rubbing  two  pieqss  of  bonnet-cane  togedier,  in  the  dark,  had  perceived  a  luminous  appear- 
ance«  This  phenomenon  was  fufficiently  novel  and  curious  to  induce  me  to  examine  it. 
«  found  that  all  canes  of  this  kiiid,  when  brifldy  rubbed  togedier,  produced  fparks  of  white 
Ugbt.  The  luminous  appearance  was  much  more  vivid  on  collifion.  When  the  canes  were 
violeatly  ftrack  together,  (parks  nearly  as  vivid  as  thofe  lix)m  the  gun-lock  were  produced. 
At  the  iame  dme  a  ftroi^  finell,  fimilar  to  diat  generated  by  die  collifion  of  flint,  or  tho 
ciDCftement  of  the  deAfic  Auid,  was  perceived. 

D.  2.  I  firft  thought  that  the  phenomenon  was  eledric,  and  depended  on  fbme  refinous 
matter  in  die  cane.  The  dedrometer,  however,  was  not  fenfiUy  aiFeded  dunng  die  experi- 
ittent.  When  the  cane  was  ftruck  againft  wood  of  any  kind,  no  fig^  was  perceived. 
When  a  cane  was  ftruck  vioiendy  againft  quartz,  agate^  or  any  filiceous  ftone,  the  lig|ht  was 
ashriQiant  as  when  two  canes  were  ftruck  together.  The  luminous  appearance  was  pro^ 
diiced  when  §iarp  fted  was  ftmek  againft  the  cane.  When  die  cane  was  ftrwck  againft  fisl<» 
phatc  of  ftrendan,  orbarytes,  or  carbonate  of  lime,  no  light  appeared 

D.  3.  Thefe  circumftances  induced  me  to  fuppofe  that  die  phenomenon  depended  -ofi 
fiUceous  cardi  in  die  epidermis,  or  in  die  whde  of  die  caae.  To  determine  this,  !  took  ^flT 
a  fia^U  quantity  of  49idrfBiis  from  one  of  die  eanes.    It  was  hard,  white,  and  had  -Tomediiiis^ 

dae 


Difcov€rj  of  Silex  in  the  Epidermis  ofVegetahhs.  5y 

^e  appearance  of  pulverized  glafs.     When  Ae  epidermis  was  removed,  the  canes  no  longer 
|)oireffed  the  property  of  giving  out  light  on  ccJlifion. 

D.  4*  To  afccrtain,  with  certainty,  the  nature  of  the  epidermis,  I  obtained  from  280 
grains  of  cane  22  grains  of  epidermis ;  this  was  expofed,  in  a  crucible,  to  the  ftrong  heat  of 
an  air-furnace  for  half  an  hour.  It  had  loft  three  grains,  was  very  white,  infufible  by  thp 
heat  of  the  blow-pipe,  and  infoluble  in  any  of  the  mineral  acids.  Ten  grains  of  it  were  kept 
in  fufion  with  cauftic  potafh,  in  afilver  crucible,  for  a  quarter  of  an  hour*  The  compound 
was  white  and  femi-pellucid.  It  was  pcrfeftly  foluWe  in  water,  without  communicating  to  it 
any  turbidity.  Wh£;n  muriatic  acid  was  poured  into  the  aqueous  folution,  a  copious  white 
flocculent  precipitate  was  produced*  This  precipitate  colIe£ted,  weighed  about  nine  grains, 
and  had  every  property  of  filex, 

D.  5.  To  determine  whether  the  wood  and  internal  bark  of  the  cane  contained  any  filex, 
I  burnt  240  grains,  carefully  deprived  of  the  epidermis,  for  an  hour.  The  aftics  were  per- 
fc6Hy  white,  and  weighed  about  feven  grains.  When  muriatic  acid  was  poured  upon  them,  a 
portion  was  diflfolved  with  effcrvefcence.  This  portion  was  chiefly  carbonate  of  potafh  9  the 
infoluble  part,  colledled,  weighed  about  two  grains,  and  was  apparently  filex. 

D.  6.  Having  afcertained,  by  thefe  experiments,  that  the  epidermis  of  the  bonnet-canc 
was  chiefly  compofed  of  flint,  and  that  the  luminous  appearance  above  mentioned  depended 
^n  this  compofition,  I  thought  it  probable  that  the  other  canes,  particularly  the  fugar-cane, 
arundo  faccharitera,  and  the  bamboo,  or  arundo  indica  %  were  fimilar  in  their  organization. 
When  two  bamboos  were  ftnick  together,  I  could  perceive  no  luminous  appearance.  Four 
ounces  of  this  cane  only  aflForded  feven  grains  of  true  epidermis.  This  expofed  to  a  ftrong 
heat,  left  five  grains  of  white  matter,  which  had  all  the  properties  of  flint.  The  rcafon  why 
thefe  canes  produce  no  light,  on  collifion,  is,  that  the  flint  of  the  epidermis  is  too  fmall  in 
quantity,  and  too  thinly  diffufed.  The  epidermis  of  the  fugar-cane  contained  a  ft  ill  fmaller 
proportion  of  flint :  200  grains  of  this  gave  five  grains  of  white  aflies,  of  which  only  one 
grain  was  infoluble  in  muriatic  acid :  the  four  grains  of  foluble  matter  appeared  to  be  car* 
bonate  of  lime.  A  large  piece  of  bamboo  (the  weight  of  which  I  am  ignorant  of)  deprived 
of  the  e[ndermis,  gave  a  confiderable  quantity  of  white  aflies,  of  which  about  two«thirds 
were  foluble  in  the  muriatic  acid :  die  infoluble  part  was  filex.  The  aflies  of  the  fugar-cane» 
deprived  of  the  epidermis,  appeared  to  be  chiefly  compofed  of  carbonate  of  lime^  and  car- 
bonate of  potafli. 

D.  7.  The  analogy  between  the  Englifli  reeds  and  graflTes,  and  die  caiieS)  and  particularly 
^e  fimilarity  of  the  appearance  of  die  epidermis,  induced  me  to  ftippofe  that  diey  might  like* 
wife  contain  filex.  On  this  fuppofition  I  firft  examined  the  amndo  phragmites,  or  cotnmon 
reed.  It  produced  no  luminous  appearance  on  collifion  with  flint.  Twenty^even  grains  6f 
€he  epidermis^  expofed  to  a  ftrong  heat,  gave  1 3  grains  of  white  earthy  matter,  insoluble  ia 

^  I  m  aware  that  the  iogenious  Mr.  Macit  difco? crcd  the  tibalbecr,  found  in  the  bamboo,  to  be  chiefly 
^ouipflfed  ol  fliat.  He,  howe? er,  did  not  tblblutely  difcover  it  in  the  wood  of  that  cane  %  and  ao  ooe,  to  my 
lUMwledge,  hat  ever  fafpefted  its  eziftence  in  the  epidermis  of  any  vegetabie.«-*2>t 

Vol.  IIL— May  1799.  I  die 


54  Silex  in  Fegitahles. 

the  mineral  acids.  Ten  grains  of  this  was  fufed  with  34  grains  of  potafli.  The  compouikl 
was  fduble  in  water.  The  nitrous  phofacid  threw  down  from  the  aqueous  folution  a  white 
flocculent  matter,  which  was  neceflarily  flint ;  this  matter  I  did  not  weigh,  but  I  conjedure 
that  it  was  about  feven  or  eight  grains.  One  hundred  and  ten  grains  of  the  reed  from  whence 
the  epidermis  was  removed,  gave  about  fix  grains  of  flint. 

D.  8.  I  now  examined  the  culm  of  wheat:  200  grains,  burnt,  gave  31  grains  of  white 
aflies  J  of  thefe  1 8  grains  were  foluble,  with  effervefcence,  in  the  muriatic  acid.  The  re- 
mainder had  all  the  properties  of  filex.  The  matter  diflToIved  in  the  muriatic  acid  was  potr 
a(h.  The  afhes  of  oats  and  barley  afforded  filex  in  nearly  the  fame  quantities  as  thofe  of 
wheat  The  cuhns  of  the  grafles,  among  which  I  examined  anthoxanthum,  poa  pratenfis^ 
and  fome  others,  appeared  to  contain  more  filex  in  the  epidermis,  than  even  the  corns  with  a 
much  larger  proportion  of  carbonate  of  potafh. 

D.  9.  The  filex  in  all  thefe  vegetables,  as  in  the  canes»  appeared  to  be  contained  in  the  epi- 
dermis, or  in  the  fecond  bark.  When  the  plants  are  carefully  burnt,  the  figure  of  the 
epidermis  is  preferred.  In  the  cane,  when  well  burnt,  it  has  a  white  glofTy  appearance,  and  ia 
femi-tranfparent.  In  the  reeds,  corns,  and  grafTes,  it  is  white  and  opaque,  and  when  viewed 
through  a  magnifier,  appears  to  confiil  of  longitudinal  threads  joined  together  by  net  work. 
Jn  the  microfcope,  even  the  fmalleft  particles  have  a  diftinft  reticular  appearance. 

D.  10*  The  quantity  of  carbonate  of  potafh  in  the  afhes  of  the  corns  and  grafTes,  in- 
duced me  to  fuppofe  that,  in  a  flrong  heat,  they  might  be  fufed  into  glafs.  The  afhes  of  tlie 
arundo  phragmites  were  expofed  to  the  ftrongefl  heat  of  an  air-furnace  for  fome  minutes ; 
there  was  no  appearance  of  fufion;  the  carbonate  of  potafh  was  not  fufficient  to  form  glafs 
with  the  filiceous  earth.  The  afhes  of  draw,  in  a  flrong  heat,  gave  a  fine  white  tranfparent 
glafs,  perfeAly  infoluble  in  water,  and  indecompofable  by  acids.  The  afhes  of  bay  gave  a 
black  glafs,  with  a  fuperabundance  of  potafh.  This  converfion  of  com  and  grafs  into  glafs, 
may  be  efFeded  by  the  blow-pipe,  and  affords  a  pleafing  experiment.  A  ftraw  burnt  with 
the  Uow-pipe,  and  urged  with  the  ftrong  heat  of  the  blue  flame,  beginning  at  the  top,  is  con? 
verted  into  a  fine  pellucid  globule  of  glafs  almofl  fit  for  microfcopic  experiments.  A  culm  of 
grafs  is  fufed  under  the  blow-pipe  into  a  globule  of  glafs,  black  and  opaque,  probably  from  its 
containing  iron. 

D.  f  I.  Thefe  fa£ts  will  afford  fome  curious  inferences  to  the  Q)eculator  on  organized 
nature.  The  flint  entering  into  the  compofition  of  thefe  hollow  vegetables,  may  be  confidered 
as  analogous  to  the  bones  of  animals ;  it  gives  to  them  flability  and  form,  and  by  being  fituated 
in  the  epidermis,  more  e&£hially  preferves  their  veflels  from  external  injury.  They  will  pro- 
bably enable  us  to  determine  whether  filex  be  a  fimple  or  a  compound  fubftance.  Reed  or 
wheat  might  be  eafily  made  to  vegetate  deprived  of  filex.  Confined  under  mercury,  in  a  foil 
compofed  of  known  quantities  of  die  £dine  earths,  and  fupplied  with  diflilled  water  and  h&i^ 
tious  air,  we  might  difcover  whether  it  would  compofe  filex,  or  fubflitute  for  it  another  earth. 
This  experiment,  as  well  as  fome  others  on  the  fiime  fubjed,  we  propofe  to  make,  if  leifure 
and  opportunity  occur.    The  numerous  complex  attradions  of  organic  beings,  refiilting  from 

their 


Gimral  Ri/v&s  $fbydfauUc  ExperinuHlt.  59 

their  rariety  of  compofition,  art  continually  producing  changes  which  the  art  of  the  chemfft 
is  unable  to  imitate.  Though  the  chemift,  at  prefent,  can  extend  his  power  no  further  by  the 
fimple  attradions  and  repulfive  motions  o(  inorganic  matter,  yet  a  path  of  fcience,  dil^ayii^ 
a  boundlefs  field  for  inveftigation.  Teems  now  open  in  the  changes  effeded  in  dead  matter 
by  living  beings.  By  difcovering  tiiofe  changes,  we  might  go  far  towards  diicovering  the 
laws  of  their  organization* 


IV. 

j/nafytlcal  Table  tf  ihe  Refulu  of  the  Courfe  ef  Experiments  on  the  lateral  Communicatltn  of 
'    Motion  in  Fluids.     By  Citizen  J.  B.  VENTURBt  f^^fiff^  tf  experimental  Philofophy  at 
Modenay  £sfr.  drawn  up  by  the  author  bimfelf  *. 


D 


ESCRIPTION  of  the  apparatus,  page  172. — It  is  proper  to  miftnift  all  theories  of 
Hydraulics,  not  excepting  that  which  is  exhibited  in  the  prefent  work,  excepting  ib  &r  as 
tiiofe  theories  may  be  fupported  by  experiment,  p.  173. 

In  any  fluid,  thofe  parts  which  are  in  motion  carry  along  widi  them  the  lateral  parts  which 
are  at  reft.  Prop.  L  exper.  i.  ibid, — I  call  this  phenomenon  the  lateral  communication  of  motion  ; 
and  I  confxder  it  as  a  principle  of  experiment,  or.elementary  b&y  without  explaining  its  caufe, 
174. — If  water  be  drawn  out  of  a  veflel  by  an  horizontal  cylindrical  pipe,  of  whidi  the  part 
neareft  the  vefTel  is  contracted  according  to  the  form  of  the  contraAed  vein  of  water  which 
flows  through  an  equal  orifice  in  a  thin  plate,  the  expenditure  will  be  increafed  by  this  pipe, 
in  the  fame  manner  as  if  ^  there  had  been  no  contradion.  Prop.  11.  exper.  3  and  4*  iHd,—' 
The  velocity  of  the  flream,  within  this  tube,  is  greater  than  that  of  the  jet  dirough  a  thin 
plate,  p.  175. — The  increafe  of  expenditure  of  water  through  an  horizontal  cylindrical  pipe, 
whether  it  be  of  uniform  diameter  throughout  or  contraded  at  the  end  next  die  refervoir,  ia 
caufed  by  the  prefTure  of  the  atmofphere.  Prop.  III.  exper.  5, 6,  7,  /*/^/.— This  increafe  of 
expenditure,  through  a  pipe,  does  not  take  place  in  the  vacuum  of  the  air  pump.  Exper.  8* 
p.  176. 

When  water  is  drawn  through  a  defcending  cylindrical  tube,  of  which  the  upper  part  is  of 
a  divergent  form,  anfwerable  to  that  of  the  contraAed  vein,  the  expenditure  will  be 
that  which  is  anfwerable  to  the  height  of  the  charge  above  the  lower  orifice  of  the  tube. 
Rectification  of  the  theory  afTerted  on  this  fubjeA  by  Guillielmini,  and  adopted  by  various 
phQofophers. — Experiments,  prop.  IV.  exper.  9,  lo,  ii,  12.  p.  I78.<— The  lateral  commu- 
nication of  motion  in  fluids  is  the  caufe  which  excites  the  prefTure  of  die  atmofphere 
to  increafe  die  expenditure  and  internal  velocity  in  horizontal  conical  tubes  of  a  certain  form. 
Prop.  V.  p.  273. — Experiments  relative  to  this  augmentation — the  refiilt  always  fidls  fliort 

*  And  fubjoined  to  hb  trcatife.— -The  paginal  numben  refer  to  the  fecood  volume  of  this  JOttDul>  except 
wkese  the  Number  III.  is  prefizedi  which  of  cMirfe  implies  the  prefent  Tolume. 

la 


6t  Gimrifl  Xijkbs'jf  bydrauUc  Expirimmit. 


of  tiieory-'Kraufe  of  this  dek6i.  Exper.  13, 14,  15.  p.  275.«— Limiti  of  die  tugmentttioiiii 
of  expenditure  in  the  fame  horizontal  conical  tube.  Exper.  16,  179  lifW.— »In  horixontai 
cjrlindrical  tubes,  the  increafe  of  expenditure  does  not  approach  the  maximuni  ib  nearly  as 
in  conical  tubes.  Prop.  VI.  exper.  18)  p.  423.— *Cafe  of  the  Ample  Cylindrical  tube  more 
particularly  examined,  ibid* — ^The  Velocity  of  the  fluid  ftream  ifluing  through  a  tube  is  lefs 
than  that  which  flows  through  an  orifice  in  a  thin  plate.  Caufe  of  this  diflRnrence.  Exper.  19^ 
p.  424.-— The  fame  law,  and  the  lame  caufes,  alfo  determine  the  expenditure  through  afcend- 
ing  and  dcfcending  tubes.  Exper.  20,21,  ibid. — The  effed  of  the  lateral  communication 
of  motion  is  produced  in  a  very  ihort  portion  of  the  length  of  the  inner  cavity  of  the  cylin- 
drical tube.  Exper.  22.  p>  425. — The  efFed  itfelf  is  greater  dian  could  ha.ve  arifen  from  the 
mutual  attraction  of  the  particles  of  the  fluid,  /i/^/•-<»The  expenditure  which  takes  place 
through  a  cylindrical  tube  of  given  dimenfiotu,  and  under  the  lame  charge,  may  be  increafed 
to  nearly  double  by  proper  adjutages.  Prop.  VIL  /^/^-^Roman  law  relative  ta  this  objedt, 
p.  426.-— Application  of  the  (ame  law  to  the  flues  of  chimnies.  Ibid», 

How  far  elbows  and  fmuofities  diminiih  the  expenditure  through  tubes^  Exper.  23. 
p.  487. — Lofs  of  expenditure  occafioned  by  enlargements  or  inflated  parts  in  tubes.  It  & 
neceflar}*  to  have  regard  to  this  in  the  conftru£Uoa  of  hydraulic  machines.    Exper.  24. 

p«488. 

In  the  machine  for  blowing  by  means  of  a  £alt  of  water,  the  air  is  afibrded  to  the  furnace 
by  the  accelerating  force  of  gravity,  and  the  lateral  communication  of  motion  combined, 
together.  Pfop<  VIII.  ibid*. — Wind  produced  by  falls  of  water  in  the  internal  parts  of 
mountains,  p«  489.  •--'The  wind  of  the  water-blowing  machine  is  not  produced  by  the  de- 
compofitionr  of  water.  Exper.  25.  p»  490. — Qixanti^  of  wind  which  one  of  theie  machines 
|S  capable  of  affording  in  a  given  time.     Ibid^ 

It  is  poffibky  in  certain  circumftances,  by  means  of  a  M  of  water,,  to  drain  a  piece  of 
ground  without  the  help  of  machines,  even  though  the  ground  ihould  be  on  a  lower  level 
dian  the  eftabliihed  current  below  the  falL  Prop.  IX.  p.  491.— ^Application  ol^  the  fame 
principle  ta  the  tail  water  of  mills.    Ibid^ 

The  eddies  of  water  in  rivers  are  produced  by  motioflb  communicated  from  themoxe  rapid 
parts  of  th^  flream  to  the  laterd  parts  which  are  lefs  rapidly  moved.  Prop.  X.  p.  492.— «• 
Vertical  Eddies  at  the  fur&ce  and  at  the  bottom  of  the  ftream  of  rivers.  Ibid^ — Thefe  cir- 
cular motions  conflitute  one  of  the  principal  caufes  of  the  lofs  of  active  &rce>  and  the  retard- 
ation of  the  current  of  rivers,,  p.  493. — ^In  a  river  of  which  the  courfe  is  permanent^  and  die 
fedions  of  its  bed  unequal,  the  water  continues  more  elevated  than  it  would  have-  done  if  the 
whole  river  had  been  equally  cootra^d^  the  dimenfions  of  its  fmallefl  fe^on.     Uid. 

Whirling  motions,  or  eddies,  formed  in  a  refervoir  kom  which  the  water  ifTues  by  an  hori-^ 
aiontal  aperture.^  Theory  deduced  from  the  do&ine  of  central  forces.  Prop.  XI.  vol.  IIL 
p.  13.  The  cavity  of  thefe  whirls  is  convex  on  the  (ide  next  the  axis.  III.  p.  14. — Phenomena 
lelattve  to  thefe  whirls,  and  thrir  explanation.    Exper.  26,  27,  28,  29,  30.  III.  p.  15. 

The  lateral  communicatiod  of  motion  takes  phce  in  the  air  as  will  as  in  water*  Prop.  XIL 

lU.  p. 


t^firauUc  BifpiriminU*^^ Art  of  Printings  6i 

Illt^p.  rit^-^Tbe  cacckatbn  of  (bund  in  organ*pipes  is  effe£^ed  by  this  communication.  Ibid. 
The  £une  onife  augments  the  force  of  (bund  in  conical  divergent  pipes.  UiJ.p.  17. — ^Re- 
markabk  differesnoes  between  the  refonant  vibrations  of  the  air  in  a  pipe,  and  the  puKations 
propagated  in  die  atmofphere,    Jiid^. 

The  contra6lion  of  the  fluid  vein  which  iflues  through  a  thin  plate,  is  not  the  Newtonian 
oatarad.  III.p*  i8.*— The  velocity  of  the  contra£led  fircam  through  a  thin  plate  is  nearly  the 
fiune  as  ttuit  of  a  heavy  body  which  may  have  fallen  through  the  height  of  the  charge.  III.  p.  19. 
— Singidar  form  of  the  ftream  which  is'emitted  through  a  long  hole  or  cleft.  Exper.  31.  IIL 
p.  ao.'—In  right-lined  orifices  the  fides  of  the  contrafted  ftream  anfwer  to  the  angles  of  the 
orifice,  and  the  contrary.  Caufe  of  this  phenomenon.  IhU. — The  contra<3ion  of  the  fluid 
vein  is  made  at  a  greater  diftance  under  a  ftrong  charge  than  when  the  charge  is  weak.  Expcr. 
32*  IIL  p.  21. — Other  varieties  in  the  figure  and  velocity  of  the  contradled  ftream..  Exper.  33 
and  34...  /iK^/.— »£x{^nditure  through  a  tube,  the  inner  extremity  of  which  is  thruft  into 
die  cavity  of  the  refervoir  itfelf.    Exper.  35..    Hid. 

V. 

j/  Memoir  onibr  Typographic  Art^  by  Alexis  Rocbon^  of  thr  French  National  Injiitutif  mtd 
Dire^or  tf  the  Marine  Ohfervatery  at  the  Port  of  Brefi. 

jL  YPOGRAFHY  is  the  art  of  multiplying  copies.  Amongft  the  proceffis  to*  which  the 
improvement  of  this  art.  has  given  rife,  there  is  one  for  ever  memorable  in  d>e  records  of 
icience  and  of  art  This  fimple  defignation  is  flifficient  to  point  out  die  invention  of  printing  y 
and  the  reader  will  be  ready  to  obferve,  that  it  is  unneceflary  to  defcribe  die  utility  of  this 
happy  e3cpedieflt^  the  fruitful  and  inexhauftible  fource  of  mental  illuminadon,  the  ever-durable 
regifter  of  all  nations.  Men  of  information  well  know,  that  the  notions  acquired  by  reading 
conftitute  the  bafis.  of  all  our  fcience  \  and  it  is  to  the  art  of  printing  that  we  are  moft  indebted 
fer  thefe  acquifitions. 

Hencefbrdi  the.  precious  depofit  of  our  fciences  and  arts  is  preferved,  and  nothing  (hort  of 
imiverial  convulfion  can  deftroy  it.  This  wonderful  art  gives  to  man  the  fiaculty  of  tranfmitting. 
die  refult  of  his  enquiries  to  hiS' fellow  men,  however  difper(ed  aver  the  fuf&ce  of  the  globe,  or 
even  though  removed  to  tbofe  periods  of  duration  which  fhall  be  occupied  by  our  remoteft 
pofterity*  .If  this,  precious  iaventioahad  been  known  to  the  ancients,  we  furely  (hould  not 
have  to  regret,  at  diis  moment,,  the  numerous  mafter*pieces  of  compoflcion,  and  the  many 
ufieftil  arts  which  time  has  for  ever  covered  with  oblcurity. 

Let  tho(e  who  fliew  ^  ignorant  contempt  for  the  mechanic  arts,.  dire&  their  attention  to 

Hhis,  andxepent  their  errors.     Let  them  renounce  thofe  unhappy  prejudices  which  tend  to  dif- 

coorage  the  numerous  and  refpefbble  clafs  of  induftrious  artifts.    Much  fagacic}'  has  certainly 

been  required  to  carry  our  arts  to  the  degree  of  perfection  they  at  prefent  poiTefs.    I  will  fay 

aaore^ .  and  bring  die  art  of  printing  19  fupport  of  my  aiIertion.^^One  iingle  happy  difcovery 

is. 


62  Invention  of  Printing. — Steridijpi  Improvemint, 

is  Tufficient  to  change  the  face  of  the  univerfe.  Let  us  leare  thofe  men  who  have  more  eradi- 
tion  than  genius  to  feek  the  origin  of  printing  in  the  ages  of  antiquitjr.  Theyare  ignorant 
that  the  great  advantage  of  tliis  art  confifts  ftill  more  particularly  in  calling  the  charaders, 
than  in  their  mobility ;  for  which  reafon  we  join  in  the  opinion  of  thofe  who  affirm  John  of 
Gottcnburgh,  Furft,  and  SchoefFer,  made  the  difcovery  in  1439-  ^e  muft,  however,  obfcrvc, 
that  SchoefFer,  the  clerk  or  principal  workman  of  the  goldfmith,  Furft,  was  the  inventor  of 
moveable  types,  according  to  the  learned  Trithcmius,  author  of  the  Chronicle  Herlanges, 
who  was  particularly  acquainted  with  Schoefier.  Trithemius  was  fo  well  (atisfied  with  this 
.procels,  that  he  gave  his  daughter  in  marriage  to  SchoeiFer.  But  whatever  may  be  the  deci- 
lions  refpe£):lng  this  point  of  hiftory,  the  immediate  objeA  of  my  memoir  will  not  allow  me 
to  enter  into  any  further  difcuffion  refpefling  the  degrees  of  pcrfe^on  which  this  art  has  fuc- 
-ceffively  acquired  fince  that  memorable  epocfia.  I  cannot,  however,  pp&  over  in  filence  a  me- 
thod invented  in  Scotland,  "by  William  Ged,  to  make  fixed  plates  with  moveable  chara^rs. 
By  means  of  thefe  plates  he  printed  an  edition  of  Salluft,  widi  the  tide  ^^  C,  Crifpi  Salujlii  Ca^ 
tUinarji  V  Juguthini  Hiftoria^  Edinburgty  GuilL  Ged^  Auri  Faber  edtnenjis  non  typis  mobilU 
bus  ut  vulgo  fieri  folet^  fed  tabellis feu  hnunis  fufis  excudebaty  1744,**  in  l6mo. 

The  Salluft  of  Ged  is  well  printed,  and  refembles,  in  every  refpedl,  a  book  printed  with 
moveable  chaiaders.  But  Ged  reduced  his  printing  chara£lers  to  a  moderate  price,  and  ob- 
tained, befides,  a  much  greater  laving  on  the  paper,  becaufe  he  printed  no  greater  number  of 
copies,  at  a  time,  than  he  had  reafonable  groui^l  to  expeS  he  Ihould  fell.  His  procefi  is 
more  particularly  advantageous  for  claiHcal  books,  which  are  of  flow,  though  fteady,  lale.  Thefe 
Polytype  plates,  as  they  are  now  called,  are  likewife  capable  of  affording  a  confiderable  profit 
to  the  founder,  who  may  make  them,  for  the  purpofe  of  exportation  or  fale,  at  great  diftances 
from  the  plac^of  fabrication.  Hoffman,  an  induftrious  artift,  communicated,  in  1784,  to  the 
French  Academy,  a  procefs  fimilar  to  that  here  defcribed ;  but  he  applied  his  art  to  the 
compofition  of  a  journal,  for  which  it  was  little  calculated.  If  we  could  flatter  ourfelves 
with  making  any  addition  to  the  fame  of  the  Didots,  we  Ihould  not  fail  to  make  honorable 
mention  of  their  labours.  But  the  obje£k  of  the  prefent  communication  is  lefs  the  art  of  printing, 
or  impreifion,lhan  of  typography.  Typography  embraces  the  generality  of  the  art  of  multiply- 
ing copies,  whether  the  plates  prefent  an  engraving  in  relief  or  excavated,  and  whether  the  cha- 
raflers  be  fixed  or  moveable.  It  will  not  be  contended,  but  that  die  art  of  typography  was 
very  anciently  known  in  China.  Duhalde,  and  every  other  writer  who  has  treated  of  the  in- 
duftry  of  that  nation,  informs  us,  that  they  transfer  to  a  block,  of  apple  or  pear  tree,  the 
work  of  which  they  are  defirous  of  multiplying  copies,  by  firft  pafting  a  written  copy,  upon 
thin  paper,  on  the  fece  of  the  block,  through  which  they  trace  the  marks  of  the  writing  with 
a  point,  and  afterwards  clear  away  the  blank  parts  with  the  graving-tooL  Duhalde  obferves, 
that  this  method  of  procuring  copies  has  the  great  inconvenience  of  requiring  an  exceffive 
multiplicity  of  blocks  for  fuch  works  as  are  voluminous.  But  how  could  it  be  poffible  for 
the  Chinefe  to  make  ufe  of  moveable  caft  types,  fince  they  have  near  one  hundred  thoufand 
charaSers*     Neverthelefs,  according  to  the  lame  author,  this  people  are  not  ignorant  of  the 

iiie 


Copper^plati  Prlnttng.-^Spiidy  iwpravtng  of  fFrlting.  63 

tife  of  moveable  cbara£lers,  becaufe  they  make  then  in  wood,  and  ufe  them  to  correal  the  Ac- 
count of  the  State  of  China,  which  is  printed  at  Pekin  every  three  months.  Duhalde  doe» 
not  hece  feem  to  be  aware  of  the  inefliniable  advantage  of  cafting  types.  The  very  celebrated 
Dr.  Frankh'n,  who  was  long  a  printer  at  Philadelphia,  (hewed  me  fome  elTays  which  he  had 
made  for  fpeedily  multiplying  the  copies  of  his  own  hand- writing.  I  do  not  here  fpeak  of 
thofe  Engiiih  prefles  which  anfwer  the  purpofe  of  a  copyiil,  but  of  a  procefs  which  gave  birth 
to  that  notion,  a  conflderable  time  afterwards.  This  method  confifted  in  wzdting  upon  (moocK 
paper,  with  ink  containing  much  gum,  which  was  afterwards  fanded  with  emery,  or  powder 
q£  caft-iron,  and  by  means  of  a  rolling-prefs,  fuch  as  is  ufed  by  the  copper-plate-printers,  the 
ftrokes  of  the  writing  were  transferred  to  a  plate  of  rofe-copper,  or  pewter.  This  plate 
affords  as  many  copies  as  the  depth  of  the  engraving  can  permit  9  but  it  muft  be  confeiTed, 
diefe  copies  are  very  far  from  being  beautiful,  and  the  ground  is  fpotted  and  foiled.  Tnough 
Franklin  did  not  immediately  committcate  his  procefs  to  me,  I  (hewed  him,  before  the 
illuftrious  Turgot^  that  by  writing  with  a  fteel  point  on  a  copper-plate,  previoufly  varnifh- 
ed,  a  more  &tis&£tory  refult  might  be  obtained  by  etching  the  ftrokes  with  nitric  acid  to  a 
liifficient  depth  for  the  fubfequent  ufe  of  a  liquid  ink  fimilar  to  that  of  the  printers.  In  this 
cafe  the  plate  may  be  wiped  without  precaution,  and  twelve  or  more  copies  may  be  pulled  o(F 
upon  coarfc  paper.  Thefc  proofis  are  foul  and  rcverfcd  ;  whence,  in  order  to  have  them  neat 
and  in  the  proper  direftion  of  the  writing,  it  becomes  neceflary  to  place  the  fame  number  of 
leaves  of  white  paper,  wetted  and  prepared,  upon  the  twelve  proofs,  and)  while  the  ink  is  ftill 
frefh,  the  whole  being  pafTed  together  through  the  roUing-prefs,  the  fame  number  of  counter- 
proofs  are  obtained  as  there  were  proofs :  fo  that  inftead  of  twelve  turns  of  the  prefs^  thirteen 
will  be  required  to  afford. twelve  counter-proofs,  very  black,  neat,  and  legible,  even  when  the 
plate  has  not  been  perfeftly  well  wiped.  This  method  is  certainly  not  to  he  compared  with 
fine  engraving ;  but  it  maybe  ufeful  in  military  operations,  and  all  other  cafes  in  which  a  fpeedy 
multiplication  of  copies  is  required.  No  precaution  is  here  neceffary :  whether  the  nitrous 
acid  be  more  or  lefs  ftrong,  or  remain  a  longer  or  (horter  time  upon  the  plate,  or  whether  the 
plate  be  fomew)iat  heated,  to  increafe  the  ftrength  of  the  folvent,  the  fuccefs  of  the  operation 
will  sever  £ul ;  provided. the  fteel  point,  made  ufe  of  to  trace  the  characSters  through  the  var- 
nifh,  (hall  lay  the  copper  perfedly  bare.  It  is  offadvantage  that  the  nitric  acid  (hould  bite  deep, 
becaufe  the  counter-proofs  are,  by  this  means,  much  darker.  The  plate  need  not  be  well 
wiped,  becaufe  it  is  of  no  confequence  whether  the  proof  which  is  ufed  to  aftbrd  a  counter- 
proof  (hould  be  very  clean,  provided  it  do  not  (pot  the  copy  intended  to  be  procured.  The 
moft  liquid  kind  of  printers'  ink  may  be  made  ufe  of. 

The- art  of  multiplying  copies  by  a  copper-plate  engraved  by  excavation,  appears  to  have 
been  an  invention  of  the  fifteenth  century.    The  Italians  and  Germans  contend  for  the  honour 
•f  this  difcovery*     This  art,,  which  is  particularly  diftinguifbed  by  the  nzme  of  eng:  aving,  is, . 
ncvcrthclefs,^  more  generally  attributed  to  a  goldfmith  of  Florence,  named  Thomas    Sini— 
guerra.    It  is  more  efpecially  ufed  to  tranfmit  to  pofterity  copies  of  paintings  and  defigns  of' 
great  maftcrs.    Engravers,  or  rather  copper-platc-printers,  have,  in  certain  circumfbuices, 

mad^ 


•64  jfccdunt  $fa  new  Machine  for  engffemng^ 

,  made  ufe  of  counter-proofs ;  but  they  are  little  efteemcd.    Thefc  counter-proofs  liive  put  rtm 
in  pofleffion  of  a  method  of  procuring,  with  celerity,  a  number  of  copies  of  a  manufcript  of  no 
•great  extent ;  and  I  can  affirm  that  diis  application  of  the  art  has  not  been  vridiout  confi* 
derable  utility.     Intereiling  memoirs,  of  which  the  impreffion  had  been  prohibited,  were 
printed  in  diis  manner.     The  fame  procefs  has  alfo  been  ufed  in  the  publication  of  flying  ga- 
zettes.    Without  attaching  any  particular  importance  to  a  procefs. of  fuch  eafy  invention  after 
what  was  previoufly  known,  I  (hall  only  add,  that  it  may  be  uTefully  applied  in  all  cafes  where 
.a  printing-prefi  cannot  be  had  recourfe  to.      The  procefs  here  delcribed  may  be  alio  found  in 
a  work  which   I  publifhed  in  1783,  on  mechanics  and  natural   philofophy.     T-heyarecon- 
i^ained.in  a  memoir,  entitled,  ^  Defcrtption  (Tune  Machine  a  graver^* 

It  was  tfie  ilkiftrious  Turgot  1^0  engaged  me,  after  thefe  firft  eflays,  to  turn  my  attention 
^  the  mechanical  method  here  defcribed-  The  reftraint  under  which  the  liberty  of  the  prefs 
^en  laboured,  caufed  this  great  man  to  wifli  that  autmrs  (hould  be  able  to  compofe  and  print 
(their  works  under  their  own  infpeftion.  The  learned  Morcllet,  who  became  ftrongly  inte- 
i^ed  in  this  projed,  gave  me  fome  punches,  whidi  I  ufed  in  my  firft  attempts.  If  I  have  not 
«ntirelj  accomplifhed  the  wiih  of  Turgot  and  Morellet,  I  have,  neverthelefs,  produced  a  ma- 
chine which  has  contributed  to  the  perfeflion  of  paper-money,  and  will  probably  be  ufeful, 
liereafter,  in  the  procefs  which  Ged  has  pointed  out  for  the  compofition  of  claffical  works.  It 
would,  no  doubt,  be  difficult,  without  the  affiftance  of  a  great  number  of  drawings,  to  fiiew, 
in  detail,  the  diflferent  parts  of  this  machine,  which  is  necefTarily  very  complicated,  though  its 
jaJSdon  is  infinitely  fimple :  for  when  it  is  ufed,  a  detent  is  held  by  one  hand,  and  the  other,  by 
tneaas  of  a  handle,  brings  the  letter  which  is  required  under  the  preffing  tool,  which  letter,  as 
well  as  its  placeo  is  precifely  indicated  by  a  moveable  piece,  which  pafles  along  till  it  is  pro- 
perly difpofed  with  regard  to  an  index :  the  detent  is  dien  let  go,  and  firmly  retains  a  wheel 
which  carries  the  letters  of  hardened  fteel :  a  fmall  lever  is  then  moved,  of  which  the  flop  is 
Aearer  or  further  o(F,  according  to  the  width  of  the  letter :  the  lever,  while  it  ftrikes  the  ftop^ 
delivers  the  preffing-fcrew  from  a  tooth  which  ftopped  its  a6tion ;  fo  that  by  thefe  three  ope- 
rations, any  letter  whatever  is  i^aced  and  ftnick  with  equal  precifion  and  facility. 

Franklin  was  defirous  of  making  a  comparifon  between  die  time  employed  with  this>  ma- 
chine, to  engrave  a  plate  of  900  letters,  and  that  required  by  a  fkilfiil  coropolitor  in  performing 
the  fame  work  bj  moveable  characters.  He  was  very  much  furprized  to  fee,  that,  without 
practice,  the  machine  engraved  the  plate  in  nineteen  minutes,  without  any  fault,  and  his  com- 
pofitor  employed  twenty-three  minutes  to  fet  up  the  fame,  vriiich  ftill  required  ft>  be 
corre&ed  *. 

A  report  of  the  cornmiifaiies  of  the  Academy  of  Sciences,  of  die  23d  December,  178 1,  will 


^  Nine  hmidred  ckanden  ire  conttined  ia  about  twelve  Unct  of  this  jovmal.  It  feemt  probable,  that  the 
inachine  of  the  author  was  worked  nearly  at  the  fame  race  as  the  eompofitor  placed  his  types  in  the  (Uck,  but 
that  the  latter  being  ncceifiuted  to  take  up  his  fpaoea,  might  lofe  time  qb  this  account.  The  fpcedieU  writer 
^ith  a  pen,  who  has  come  under  my  obfcrvatioa,  would  have  writtem  the  Xame  ^uaatitji  perfectly  legible,  in 
1^  minutes. — N. 

fcrvc 


Repmrt  cMKimii^  a  Machine  for  4npraviug.  6g 

fervc  to  give  a  firft  notion  of  this  machine.  **  The  charaders  intended  to  be  engraved  are  dif. 
pofed  in  a  circle,  on  a  movekble  wheel,  fucceffively  brought  under  a  preffing-fcrew,  which 
engraves  them  upon  a  plate  of  pewter.  The  inventor  has  imagined  different  means,  as  well 
for  fpeedily  bringing  die  defired  charafler  beneath  the  fcrew,  as  to  regulate  the  prefTure  in 
proportion  to  the  extent  of  the  letter  itfelf,  in  order  that  all  the  different  impreffions  may  be 
made  to  the  fame  depth.  The  plate  itfelf  has  a  d6uble  motion,  one  of  which  ferves  to  fpace 
the  letters  and  the  words,  and  the  other  to  regulate  the  diflance  between  the  lines.  Thefe  mo- 
tions are  performed  in  fuch  a  manner,  that  any  diflance,  at  pleafure,  may  be  allowed  between 
tile  letters,  the  words,  and  die  lines,  and  thefe  diflances  poffds  the  moft  perfed:  equality. 
The  differept  widdis  of  the  letters  prefcnt  an  obflach  here :  in  faft,  it  may  eafily  be  under- 
ftood,  that  in  order  to  render  thefe  fpaces  equal,  it  is  neceffary,  aoi  that  the  letters  themfelves 
ihould  occupy  equal  portions  of  the  line,  but  that  a  conftant  interval  fliould  be  allowed  be- 
tween them.  The  beauty  of  printing,  likewife,  demands  that  thefe  fpaces  fhould  be,  in  fome 
inftances,  varied  in  a  fmall  degree,  in  order  that  the  juftification  (hould  be  perfe<^  that  is  to 
fay,  diat  the  ends  of  the  lines  (hould  prefent  to  the  eye  a  regular  and  ftraight  termination. 
The  machine  of  our  audior  affords  the  means  of  doing  this. 

^*  This  machine  appears  to  us  to  unite  feveral  advantages :  i.  Engraved  editions  of  books 
may  be  executed,  by  this  means,  fuperior  to  thofe  which  can  be  made  by  the  hand  of  the  en- 
graver, however  fkilful ;  and  thefe  engraved  originals  will  be  made  with  much  more  fpeed, 
and  much  lefs  expence.  2.  As  diis  machine  is  portable,  and  of  no  confiderable  bulk,  it  may 
become  very  ufeful  in  armies,  fleets,  and  public-offices,  for  the  impreffion  of  orders,  inftruc- 
tions,  &c«  3.  It  poffeffes  the  advantage  which,  in  a  variety  of  circumftances  is  highly 
valuable,  of  being  capable  of  being  ufed  by  any  man  of  intelligence  and  fkill,  without  requir- 
ing the  affiflance  of  any  profeffional  workman.  And,  laftly,  it  affords  the  facility  of  waiting 
for  the  entire  compofidon  and  engravings  of  a  work  before  any  of  the  copies  are  pulled  off;  the 
expence  of  plates,  even  for  a  work  of  confiderable  magnitude,  being  an  ohjeSt  of  litde  charge; 
and  this  liberty  it  affords  to  authors,  may  prove  highly  beneficial  in  works  of  which  the  chief 
merit  confifts  in  the  order,  method,  and  connexion  of  ideas. 

^  So  that  even  if  it  (hould  prove,  as  experience  only  can  fhew,  that  it  could  not  acquire  the 
tune  fpeed  as  die  common  method  of  printing,  nor  an  equal  degree  of  facility  for  alterations 
and  cor  regions,  it  would,  neverthelefs,  be  of  very  great  utility. 

<<■  We  think,  therefore,  that  the  idea  of  this  machine  being  new,  and  the  means  adopted  by 
the  inventor,  to  give  it  the  degred  of  perfeAion  to  which  it  is  brought,  being  fimple  and  inge- 
nious, and  its  application  being  of  great  utility,  the  fame  is  worthy  of  the  approbation  of  die 
Academy ;  and  that  the  defcription  of  the  machine,  executed  with  the  machine  itfelf,  and 
prdented  by  the  author,  is  worthy  of  being  publifhed  under  the  privilege  of  that  Academy; 

(Signed)        «<  CoNDORCBT  and  Bossut. 
*  Given  at  die  Louvre,  «2nd  December,  1781/* 
Vol.  III.— May  1799,  K  DefmftUn 


46  Ditait  of  thi  Qnftruilion  rf    ' 

Defer tption  of  the  Machine  for  Engravings 

Tbis  B^'achine  conGfts  of.  two  brafs  wheels,  placed  oa  the  iame  axis  above  each  other,  and 
fcparated  by  a  number  of  pillars^  each  two  inches  in  lejngth  (Plate  III).  Thefe  two  wheels^ 
with  the  interval  which  feparatcs  them,  are  equivalent  to  a  iingle  wheeL  about  three  inches  thick* 
In  order,  therefore,  to  fimplify  my  defcription,  I  fhall  confider  them  as  a  fingle  wheel  whkfai 
moves  freely  on  its  axis. 

This  wheel  is  perforated  near  its  circumference  with  a  number  of  fifuare  holes,,  which  are 
the  (heaths  or  fockets  through  which  a  like  number  of  fteel  punches,  of  the  fame  (hape,  are 
infertedy  and  are  capable  of  moving  up  and  down..  They  are  very  well  fitted,  and  from  this  cir- 
cumdance,  as  welL  as  the  thicknefe  of  the  double  wheet,  they  have  no  (bake,-  or  fide  motion^ 
independent  of  the  motion  of  the  wheel  itfelf.  Every  punch  is  urged  upwards  by  a  feparate 
Q)ring,  in  fuch  a  manner,  that  the  wheel  armed  with  its  cfaara£ters,  or  fteel  types,  (the  lowec 
£ices  of  the  punches  being  cut  into  the  figures  of  the  feveral  letters),  may  turn  freely  on. its 
axis  \  and  if  it  be  moved,  the  ieveral  punches  will  pais  in  fiicceffion  beneath  an  upright  (crew, 
for  prefllire.  The  fcrew  is  fixed  in  a  very  fir m  and  iblid  fi-ame,  attached  to  the  fupports  of 
the  machine ;  and  by  this  arrangement,  a  copperplate,  difpofed  on  die  table,  or  bed  of  the. 
apparatus,  will  receive  the  impreffion  of  all  the  punches  in  fucceffion,  as  they  may  be  brought 
beneath  the  vertical  preffing-fcrew,  and  fubje£bd  to  ita  adion.. 

But  as  the  pseis  is  fixed,  it  would  neceilarily  follow  that  each  fucceffive  imprcifion  would, 
in  part,  deftroy,  or  mutilate,  the  previous  imprefSons,  unkfs  the  plate  itfelf  were  moveable. 
It  therefore  becomes  necefTary  that  the  plate,  (hould  be  moveable  in  two  dire£lions ;  the  firft 
to  determine  th&  interval  between  the  letters  and  words,  and  form  the  lines ;  and  the  other  mor 
tion,  which  is  more  fimple,  becaufe  its  quantity  may  remain  die  fame  through,  the  whole  of  a 
book»  ferves  to  give  the  interval  between  line  and  line,  and  to  form  the  pages. . 

It  will  eafily  be  conceived,,  that  it  would  be  a  tedious  operation,  to  feek,  upon  the  circum- 
ference of  the  wheely  each  feveral  character,  as  it  might  be  required  to  come  beneath  the  prefs, 
becaufe  it  is  neceflary  to  repeat  this  operation  as  manydmes  as.  there  are  charadters  in  a  worb 
I  have  confiderably  diminiflied  the  dme  and  trouble  of  this  operadon,  by  fixii^  upon  the  axis 
of  the  gj:eat  wheel,,  which  carries  the  punches,,  another  finall  wheel,  about  four  inches  in  diar 
meter,  the  teeth  of  which  2&  upon,  a  rack,  which  carries  a  rule  moving  between  two  Aiders. 
This  rule,  or  flraight  line,  will,  therefore,  reprefent  the  developement,  or  unfolding  of  the  cir- 
cumference of  the  wheel  which  caufes  it  to  move,  and  will  (bew  the  pofidon  of  the  great 
wheels  which  carries  the  punches..  For  theie  two  wheels  being  concentric,  the  developement 
of  the  fmall  toothed  wheel,  of  about  two  bches  radius,  will  exhibit,  in  a  fmall  fpace  (for  ex- 
ample, that  of  a  foot),  an  accurate  regifter  of  the  relative  pofidons  of  the  punches,  with 
regard  to  die  preffing-fcrew.  To  obtain  this  efle^  nothing  more  is  neceflary  than  to  place  a 
fixed  index  oppofite  the  moveable  rule,  which  lafl  ia  divided  in  the  following  manner:  * 
The  punch  on  which  the  firfl  letter  of  the  alphabet  is  engraved,  muil  be  brought.undei  the 

centrcL 


yf  Machiutfir  engraving  nutallic  Plates.  6^ 

centre  of  <the  prefllng-fcrew ;  and  a  line  of  divifion  then  drawn  upon  the  moveable  ri2le»  to 
ivhich  the  letter  itfelf  muft  be  added  to  diftinguiOi  it.  The  index,  already  inenttoned,  being 
'placed  oppofite,  and  upon  this  firft  divifion,  will  ferve  to  place  immediately  beneath  the  preflT- 
ing-icrewy  the  punch,  ar  rather  the  chara£ler,  correfponding  with  the  divifion  upon  the  rule, 
without  its  being  afterwards  ncccffary  to  infpeft  the  place  cither  of  the  punch  or  the  fcrew, 
with  regard  to  each  other.  Confequently,  as  foon  as  the  divifions  which  correfpond  with  all 
the  punches  inferted  in  the  wheel,  are  engraved  upon  the  ftraight  rule,  Uie  fixed  index  will 
hnmediately  determine  the  pofition  into  which  that  wheel  muft  be  brought,  in  order  to  place 
the  punches  under  the  preffing-fcrew,  in  the  order  which  the  work  may  require. 

This  rcgiftcr  (tableau) ^  for  by  this  name  I  (hall  hereafter  diftinguifli  the  rule  and  its  index, 
has  no  other  fun<^ion  in  the  machine,  than  to  guide  the  hand  of  die  operator,  and  to  (hew 
when  the  punch  is  very  near  its  proper  pofition  beneath  the  preiling-fcrew.  When  this  is  the 
cafe,  the  required  pofition  is  accurately  obtained  by  means  of  a  detent,  or  catch. 

The  detent  which  I  ufe  for  this  operation,  is  a  lever  with  two  tails,  one  of  which  is  urged 
toward  the  circumference  of  the  wheel,  by  a  fpring.  To  this  extremity  of  the  lever  is  fixed  a 
f)iece  of  hardened  fteel,  which  has  the  figure  of  a  wedge,  which,  by  means  of  a  fpring,  is 
preded  towards  the  axis  of  the  great  wheel,  but  may  be  relieved,  or  drawn  back,  by  pre(ruro^ 
4>n  the  oppofite  tail  of  the  lever,  fo  as  to  permit  the  great  wheel  to  revolve  at  liberty. 

In  the  next  place  it  muft  be  explained  how  this  detent  takes  hold  of  the  wheel,  fo  as  to  re- 
tain it  precifely  in  the  fituation  neccflary  to  caufe  any  one  of  the  punches,  at  plcafure,  to  give  its 
'impre(fion  to  the  plate*  For  this  purpofe  there  are  a  number  of  notches  eut  in  the  circum- 
ference of  the  wheel,  for  the  purpofe  of  receiving  the  detent.  Thefe  notches  may  be  about 
half  an  inch  deep,  wider  towards  the  circumference  than  elfewhere,  and  it  will  be  of  advantage 
that  this  outer  width  (bould  be  as  great  as  the  circumference  of  the  wheel  can  conveniently 
allow.  By  this  contrivance,  the  wedge  will  not  £ul  toprefent  itfelf  oppofite  one  of  the  notches 
into  which  it  will  fall,  and  draw  the  wheel  exa£Uy  to  its  due  fituation,  even  though  the  index  of 
the  regifter  (hould  not  be  brought  preci(bly  to  the  line  of  divifion  appropriated  to  any  particular 
letter.  For,  if  this  laft  degree  of  precifion  were  required  in  working  the  machine,  it  would  be 
very  prejudicial  to  the  requifite  fpeed  which,  above  all  things,  is  required  in  its  ufe.  When  the 
wedge  is,  therefore,  left  at  liberty,  it  not  only  enters  immediately  into  its  place,  and  moves  the 
wheel  till  its  two  fides  apply  foirly  to  the  interior  furfaces  of  the  notch,  but  retains  the  wheel  ia 
this  ftate  with  the  neceflary  degree  of  ftability. 

The  method  of  giving  the  proper  figure  to  thefe  notches  is  very  eafy.  For  this  purpo(e 
nece(ra]:y,  in  the  firft  place,  to  impre(s  all  the  charaders  contained  in  the  wheel,  on  a  plate  of 
copper  or  pewter.  The  fupport  on  which  the  plate  is  fixed  muft  be  moved  in  a  right  line,  after 
each  ftroke  of  the  punch,  through  fucha  fpace,  that  the  characters  may  be  arranged  ono.  after 
the  other  without  touching.  Now,  as  the  perfed  linear  arrangement  ( fuppofing  every  other  part 
to  ^e  true)  muft  depend  on  the  notches,  it  might  Teem  fu(Ecient  to  cut  thefe  according  to  die 
method  ufed  for  the  wheels  of  clock-work  :  but  as  it  is  very  difficult  to  avoid  fome  obliquity 
on  the  face  of  the  punch,  and,  perhaps,  in  th^  hole  through  which  it  pa(res,  it  is  in  almoft  t^trj 

K  a  cafe 


68  Dit^H  t>f  the  Conftruiilon  9f 

cafe  neceflary  to  retouch  the  notch  itfelf.  The  requifite  degree  of  precQion  may  be  eafilf 
obtained,  when,  upon  examining  with  attention  the  print  of  the  chara^rs  engraved  upoa 
the'  plate,  the  inequalities  (hall  have  been  afcertained  by  a  very  fine  line  pafling  exadljr  under 
the  bafe  of  two  fimilar  letters,  afTumed  as  obje£h  of  comparifbn :  for  the  irregularity  of  linear 
pofition  may,  by  this  means,  be  determined,  with  great  exa£biefsy  and  remedied  to  the  moflr 
extreme  nicety.  In  this  operation,  the  workman  muft  file  away  part  of  diat  furbce  of  the 
notch  which  is  oppofite  to  the  dire^on  of  the  motion  the  charader  requires.  Great  care 
muft  be  taken  to  file  only  a  (mail  portion  at  a  time,  in  order  that  the  inflrant  may  be 
feized  at  which  die  wedge,  by  entering  into  the  notch^  brings  the  charafter  to  its  due 
fituation. 

Thefe  details  refpe<%ng  the  right-lined  arrangement  on  the  charaAen^  muft  not  divert  our 
attention  from  the  very  great  celerity  with  which  any  letter  is  brought  to  its  place  under  the 
prefs,  by  means  of  the  regifter  and  detent*  This  celerity  is  an  obje£fc  of  fo  much  importance 
in  the  engraving  of  a  great  work,  that  every  means  ought  to  be  purfued  which  may  tend  ta 
increafe  lU  For  this  reafon  it  is,  that  inftead  of  fbUowing  die  alphabetic  order  in  the  arrange 
ment  of  punches  on  the  fur&ce  of  the  wheel,  we  ought  to  prefer  that  in  which  the  (um^ 
of  the  difFerent  motions  to  be  given  to  the  wheels  for  engraving  an  entire  work,  (hall  be  the 
leaft  poffible.  This  tedious  enquiry  may  well  be  difpenfed  with>  by  obferving  the  order  in 
which  printers  di^ofe  their  cafes  of  chanuSers^  that  the  letters  of  the  moft  frequent  recurrence 
may  be  moft  immediately  under  the  hand  of  the  workman. 

If  all  the  characters  afforded  an  equal  refiftance  to  impreffion  in  a  pkte  of  metal,  a  conftant 
force  would  never  fail  to  drive  the  pttnches  to  the  fame  depth.  But  the  faces  of  the  letters 
are  very  unequal,  and,  confequemly,  it  will  be  neceflary  to  ofe  a  variable  force.  Moft  work^ 
men  ufe  the  hammer>  and  not  a  fcrew^  as  in  dus  machine,  for  ftamping.  If  the  hammer  had 
been  ufed  in  this  machine,  it  is  evident  diaC  if  we  (uppofed  it  to  have  fallen  from  the  fame 
height  upon  every  one  of  die  punches,  die  force  of  the  ftroke  could  be  rendered  variable  ac- 
Cdrdlng  to  the  nature  of  the  cbaraders,  by  placing  a  c^tal,  or  head,  upon  each,  of  an  height 
properly  a^ufted  to  receive  the  hammer  after  paffing  through  a  greater  or  lefs  fpace.  Bat 
die  heads  of  our  punches  are  variable  at  pte^fure^  becaufe  they  are  (crewed  on ;  and  thus  it  is 
diat,  by  experimentally  adjufting  die  heads  of  all  the  punches,  a  fet  of  impreffions  are  obtained, 
*  of  equal  depths  from  every  one  of  thenv  When>  for  example,,  the  letter  /  is  placed  under  the 
hammer,  the  upper  part  of  its  head  is  at  a  fmall  diftance  from  die  head  of  the  hammer,  in 
order  that  its  fall,  which  begins  always  at  the  fame  place,  may  ftrike  diis  letter  weakly ;  but 
when  the  letter  M  is  brought  under  the  hammer,  the  upper  part  of  its  head  being  much  lefs 
elevated  than  that  of  the  letter  i,  will  receive  a  much  ftronger  Wow.  The  impreffions  of  the 
letter^  M  and  /  will,  therefore,  always  .be  equally  deep,  if  the  heads  of  the  punches  be  once 
properly  fixed  by  experiment. 

Though  I  have  already  obferved,  that  the  prefTure  in  this  machine  is  given  by  means  of  a 
fcrewx  I  (hould  certainly  have  ufed  the  hammer^  if  it  were  not  for  the  inconvenience  arifing 

^  booft 


A  Machimfor  engraving  mtaUic  Platen,  69 

from  the  tremulous  motion  it  gives,  particularly  to  thofe  parts  which  are  hammer-hardened  ^. 
The  prefTure  of  a  fcrew  has  not  the  fame  inconvenience.  Its  effect  is  gradually  performed, 
without  occafioning  thofe  fudden  jars  fo  inimical  to  precifion  and  durability  of  a  machine. 
It  neverthelefe  happens^  in  fome  inftanceS)  that  the  imprefiion  on  metals  made  by  a  fcrcw> 
do  fometlmes  partake  of  the  circular  motion  of  the  fcrew;  but  this  defe£t  maybe  avoided,  by 
giving  its  threads  a  great  inclination.  The  fcrew  I  make  ufe  of  has  eight  (breads,  which  are 
fo  inclined  that  it  runs  through  its  female  focket,  and  would  fall  out  merely  by  its  own  weight. 
This  conftru6lion  affords  the  double  advantage  of  preferving  the  impreffions  from  the  eiFedls 
of  the  circular  motion,  and  of  affording  a  fall  in  the  fcrew  of  nearly  nine  lines  for  each  revolu- 
tion. The  head  of  this  fcrew  is  folidly  fixed  in  the  centre  of  a  brafs  wheel,  of  which  the  poG- 
tion  is  horizontal.  The  diameter  of  this  wheel  mufl  be  fuf&ciently  large,  that  its  motion 
may  not  be  perceptibly  afFecled  by  the  irregularities  of  firi£kion  in  the  fcrew.  This  confi- 
derable  diameter  is  alfo  requifite,  becaufe  the  prefTure  of  the  fcrew  depends  not  only  upon  the 
force  which  is  applied,  but  the  difbnce  of  the  place  of  application  from  the  centre  of 
movement. 

It  is  efTential  that  this  wheel  (bould  have  very  little  (hake ;  for  which  reafon  it  is  advifeaWe 
that  the  axis  of  the  fcrew  (bould  be  prolonged  above  the  wheel  itfelf,  that  it  may  Aide  in  a 
focket  firmly  fixed  to  the  frame  of  the  machine.  In  this  fituation,  the  wheel,  which  is  fixed  on 
the  prolongation  of  the  fcrew,  will  have  its  plane  confla;itly  preferved  in  a  fituation  parallel  to 
itfelf,  without  any  libration,  notwithftanding  the  rife  and  fall  of  near  nine  lines,  or  three 
quarters  of  an  inch,  which  it  undergoes  for  each  revolution  on  its  axis. 

It  has  been  ftated,  as  a  requifite  condition,  that  die  fcrew  fhould  conftantly  fell  from  the 
lame  fixed  point,  or  elevation,  upon  the  heads  of  every  one  of  the  punches.  To  accompliih 
this  eflendal  purpofe,  a  lever  is  firmly  fixed  to  the  fupport  of  the  fcrew,  which  lever  refembles 
die  beam  of  a  balance,  having  one  of  its  extremities  armed  with  a  claw,  and  the  other 
ferving  to  give  it  motion  through  a  fmall  vertical  (pace.  The  claw  falls  into  a  notch  ki 
die  upper  furface  of  the  wheel  attached  to  the  fcrew,  as  foon  as  that  wheel  has  rifen  to  ' 
Ae  deiired  elevation,  and  the  lever  itfelf  is  fo  fer  limited  in  its  motion,  that  it  cannot  take 
bold  of  the  wheel,  excepting  when  it'has  reached  diat  height.  The  wheel,  therefore,  remains 
confined  and  immoveable,  by  means  of  this  detent,  and  cannot  defcend  until  it  is  delivered 
by  prefliire  upon  tlK  oppofite  tail  of  the  lever.  In  my  machine,  the  wheel  which  has  die  preffing 
fcrew  for  its  axis,  does  not  perform  an  entire  revolution.  It  was  with  a  view  that  there 
might  never  be  any  fall  capable  of  (baking  and  diflurbing  the  machine,  that  I  determined  to 
ufe  only  two-thirds  of  a  revolution  to  ftrike  thefe  punches,  which  aflbrd  die  ftrongefl 
xefiftance*    The  fcrew  confequently  fells  only  through  fix  lines,  upon  thofe  heads  which 

^  Whicb  alters  their  figure,  and  loofens  the  fittings.  The  tSc6k  of  agitation  or  firoke,  in  reftoriag  bam- 
mer-hardened  metals  to  their  original  date,  is  well  known  to  workmen.  Filing  and  turning  of  hammer* 
hardened  ficel,  in  particular,  caufes  it  to  regain  its  figure.  Thus,  for  example,  when  a  circular  faw  is  ground, 
and  flattened  by  the  hammer  of  the  faw  maker,  it  cannot  afterwards  be  rendered  thinner  and  truer  in  the  lathe, 
.WcavTe  the  point  of  the  gravcf' produces  #  tremulous  motion  which  recnoYcs  the  cfic6t  of  the  hammer.—^. 

are . 


7  0  Ditall  tf  ibe  Confiruilm  9f 

are  leaft   elevated,  and  aboct  two  lines  upon  thofe  which   ftand  higheft.     Whence  th^ 
•difference  between  the  extreme  heights  does  not  exceed  four  lines. 

It  is  obvious,  that  fo  fmall  a  difference  is  not  fufficient  to  firike  all  the  characters  From 

M  to  the  letter  i,  when  the  wheel  which  governs  the  fcrew  is  put  in  motion  by  a  conftant 

weight,  of  which  the-  impulfe,  like  that  of  the  hammer,  is  inereafed  only  by  the  acceleration 

of  its  fell.     It  is  evident  that  this  requifite  variation  of  force  might  be  had  by  changing  the 

weight;   but  it  is  equally  clear^  that  the  numberlefs   and   inceflant  changes  which  the 

engraving   of   an   entire  work  would  demand,  would  be  incompatible  with   that  degree 

of  fpeeJ  which  forms  one  of  our  firft  requiAtes.     I  was,  therefore,  obliged  to  render  the 

force  of  the  weight,  which  turns  the  fcrew,  variable,  by  caudng  it  to  zck  upon  levers  of  greater 

or  lefs  lengths,  according  to  the  different  quantities  of  impulfe  required  by  the  feveml 

punches.     For  this  purpofe,  I  adopted  the  following  conftrudion.     I  connected  by  a  ffcel 

•chain  to  the  wheel,  which  moves  the  fcrew,  another  wheel,  having  its  axis  horizontal,  fo  that 

<he  two  wheels  refpe6tively  command  each  other.     They  are  of  equal  diameter,  and  the 

chain  is  no  longer  than  to  make  an  entire  turn  round  each  wheel.     This  fecond  wheel  or 

leading  pulley,  is  intended  to  afibrd  the  requifite  variations  of  force,  which  it  does  by  means 

of  a  fnail  fixed  upon  its  axis.     The  fnail  is  a£led  upon  by  a  cord  paffing  ov«r  its  fpiral 

circumference,  or  groove,  and  bearing  a  weight  which  is  only  to  be  changed  when  a  new 

fet  of  punches  for  charaders  of  a  different  fize  are  put  into  the   great  whed.       The 

fpiral  is  fo  formed,  that  when  the  weight  defcends  only  through  a  fmall  fpace,  the  part  of  the 

cord,  which  is  unwound,  ads  at  a  very  (hort  diftance  from  the  center  of  the  pully;  but 

when  the  fall  is  greater,  the  part  of  the  fiiail  upon  which  it  a£b  is  fo  far  enlarged  as  to 

afford  a  much  longer  lever,  and,  confequently,  to  give  a  proportionally  greater  effeA  Id 

Che  ftroke.     This  conftru£tion,  therefore,  by  giving  the  advantage  of  a  longer  lever  to  a 

greater  fall  of  the  fcrew,  affords  all  the  power  which  the  nature  of  the  work  and  the 

<liffcrent  fpaces  of  the  letters  demand. 

The  fupport  on  which  the  plate  is  fixed,  mufl,  as  has  before  been  remarked,  move  fo  as  to 

form  ftraic  lines.   This  motion,  which  ferves  to  fpace  the  different  chara&ers  with  precifion, 

IS  obuined  by  means  of  a  fcrew,  the  axis  of  which  remains  fixed,  and  carries  a  female  fcrew  or 

nut.    The  nut  itfelf  is  attached  to  the  fupport  of  the  metallic  plate,  which  deceives  the 

letters  and  carries  it  in  the  right  lined  diredion  without  any  deviation,  becaufe  it  is  confined 

in  a  groove  formed  between  two  pieces  of  metal.     The  fcrew  is  moved  by  a  lever  which 

can  turn  it  in  one  .direflion  only,  becaufe  it  ads  by  a  click  upon  a  ratchet-wheel,  which  is 

fixed  to  the  head  of  the^ fcrew.     The  adion  of  this  lever  always  begins  firom  a  fixed  ftop  ; 

4}ut.the  fpace  through  which  it  moves  is  variable,  according  to  the  refpedive  breadths  of  the 

letters.     This  new  confideration  induced  me  to  fix  upon  the  rule  or  plate  of  the  regifter,  a 

number  of  pins,  correfponding  with  the  different  divifions  which  anfwer  to  each  punch  ; 

Ihcfe  pins  determine  thediflance  to  which  the  lever  can  move.     It,  therefore,  becomes  a  con» 

dition  that  its  pofition  in  the  machine  fhould  be  oppofite  the  fixed  index  which  determines 

ihe  ch^ader  at  any  time  beneath  the  prefGng-fcrew.    The  lever  and  its  pin  are,  therefore, 

the 


A  Machine  fir  tngravhg  rmtallh  Plate f.  %t 

Ae  fole  agents  employed  to  tpKt  die  charatSlers*  If  the  plate  were  not  moved  by  the  lever^ 
the  impreflions  would  fdW  upon  each  other,  and  thus,  for  example,  the  letter  i  would  be  totally 
obliterated  by  the  impre/Hon  of  the  letter  L 

Whenever,  therefore,  it  is  required  to  difpofe  the  letters  /  and  /  bcfidc  each  other,  the 
plate  mufl  be  moved  after  ftriking  the  letter  i  through  a  fpace  eqyal  to  the  quantity  of  the 
deiired  operation.  Suppofe  this  to  be  one  fourth  of  a  line,  and  that  the  lever  ihould  run- 
through  an  arc  of  ten  degrees  to  move  the  plate  through  this  quantity  :  as  foon  as  the  pin 
of  the  letter  /  fhall  be  adjufted  to  the  neceflary  length  to  enable  the  lever  to  defcribe  an  arc 
of  ten  degrees,,  the  operation  of  fpacing.  the  two  letters  i  and  /  will  be  reduced  to  thac  of 
placing  the  lail  letter  beneath  the  fixed  index,  and  moving  the  plate  till  the  lever  fhall  be 
(lopped  by  the  pin  belonging  to  the  letter  L  All  the  other  letters  will  be  equally  fpaced,  if 
die  difpofition  of  the  punches  in  the  wheel  be  fuch,  that  the  laft  ftroke  of  any  letter  fhall* 
confound  itfelf  with  any  letter  of  a'  fingle  ftroke,  fuppoflng  them  to  be  imprefted  one  after 
the  other,  without  moving  the  lever  between  ftroke  and  ftroke.  This  arrangement  deferves- 
to  be  very  ferioufly  attended  to,  becaufe  the  procefs  could  not  be  performed  without  it. 

Many  well  informed  perfons  are  of  opinion,  that  the  perfect  eq^uality  which  this  machine 
for  engraving  affords  in  the  formation  of  letters  and  figns  the  moft  difficult  to  be  imitated, 
may  afford  a  means  of  remedying  the  dangers  of  forgery.     It  is  certain  that  the  performance 
exhibits  a  fimple  and  ftriking  charader  of  precifiotiy  which  is  fuch,  that  the  leaft  experienced- 
eyes  might  flatter  themfelves  ia  certain  caies  to  diftinguifli  counterfeits  from  originals.     My 
unfortunate  colleague,  Lavoifier,  whom  the  friends  of  fcience  and  the  arts  will  notceafetO' 
jcgret,  made  fome  experiments  of  this  kind  for  the  caijfp  d*efcompte  which  were  attended  with- 
perfect  fuccefs.     Ardfts  appointed  for  that  purpofe  endeavoured,  in  vain,,  to  imitate  a  vignette- 
formed  by  the  fucceffive  and  equal  modon  of  a  character  of  ornament*.    My  firft  machine 
for  engraving,  was  executed  by  Carrochez,  with  whom.  I  had  very  much  trouble,  from  die- 
affiduity  with  which  it  was  neceflary  to  attend  to  his  operations.     I  was  more  fortunate  in  the 
conftrudion  p£  the  iecond ;  a  Ikilfol  ardft,  Richer,  executed  this  for  a  lover  of  the  arts>. 
with  a  degree  of  intelligence  which  was  altogether  furpriAng,  and  he  even  rendered  it  more 
perfe£t  by  the  addidon  of  a  (hail.     The  third  machine  of  this  kind,  which  was  intended  for 
the  fabrication  of  affignats,  is  not  finiftied.    It  is  by  the  iame  ardft. 


While  I  was  employed  ih  the  conftru£don  and  improvement  of  my  machine  for  engraving,  ^ 

Condorcet  engaged  me  to  make  ufe  of,  in  a  (hort  memoir  of  die  celebrated  Dupad,  a  method 

I  had.  imagined  to  compofe  a  large  work  with  a  very  fmall  number  of  types.    I  complied  with 

his  demand,  and  prefented  to  the  academy  a  polytype  plate,  endtled  E£ai  d' imprimerUy  prefenti: 

i  r academe  des  fciences  le  8  Fevriery  1786. 

The  number  of  moveable  caft  types  which  I  poflefled,  was  contained  in  a  box  of  the 
£>rmof  a  book,  and' was  fuflicient  to  compofe  only  four  lines.     When  thefe  four  lines  were* 

'^Thit  argument  feemt  to  apply  only  u^on  the  fuppoiitioa  of  the  machine  itfelf,^ being  generaUyun. 

known  to  the  pub)ic.*«>N. 

Gomppied^, 


» 


y2  On  ihi  polytypic  Art. 

compofed,  I  took  their  impreflion  in  fine  piaifter,  mixed  with  charooal-duft* ;  this  mouIS 
enabled  me  to  caft  a  number  of  copies  of  the  four  lines  which  I  had  compofed.  I  foon  per- 
ceived that  the  iirft  and  laft  letter  of  each  Une  loft  its  pofition'by  finking  fiirdier  back  than 
the  hce  of  the  other  letters.  It  was  eafy  for  me  to  obviate  this  defeS,  by  placing  a  ftnall 
metallic  fupport  at  a  certain  diftance  from  the  beginning  and  end  of  each  tiney  to  prevent  the 
finking  of  the  letters.  It  is  fcarcely  nccefTary  to  remark,  that  the  mould  ought  to  be  very  dry, 
and  that  a  flight  preiTure  upon  the  metal  while  in  the  half  fluid  ftate)  is  ufefiil  to  obtain  a  good 
plate  :  feven  or  eight  of  thefe  are  required  to  form  a  page  in  odavo*  I  can  take  upon  me  to 
affert,  that*  this  procefs  is  neither  tedious  nor  embarraffing,  and  it  has  the  convenience  of  in- 
cluding the  power  of  making  correSions  and  additions. 

This,  in  fhort,  is  the  account  I  have  to  give  of  my  enquiries  into  the  typographic  art 
Retb,  formerly  direAor  of  the  fabrication  of  affignats,  is  better  acquainted  than  any  other  perfon 
with  what  has  fmce  been  done  for  the  improvement  of  this  important  art.  I  have  but  a  few 
words  to  add.  In  my  eflfay  on  ancient  and  modem  coins,  I  defcribed  a  method  of  imitating 
ancient  and  modern  coins  in  bell-metal,  by  the  polytypic  art.  For  this  purpofe  I  place  in  a 
cavity  in  an  anvil  the  p  ieceof  bronze  heated  to  a  proper  degree,  to  render  it  foft :  the  ufe  of 
the  cavity  is  to  enable  the  metal  to  fufbin  the  a^on  of  that  preflure  which  it  is  to  receive 
from  the  fcrew  or  ram  at  the  inftant  the  medalljion  is  applied  to  it)  which  is  intended  to  give  its 
liollow  impreffion.  If  the  metal  be  heated  to  a  proper  degree  of  fofbieis,  die  original  will 
not  be  in  the  leaft  altered,  whether  it  be  of  gold,  filver,  or  copper ;  but  it  is  requifite  diat  the 
f>iece  fhouldnot  be  fuffered  to  become  hard  by  cooling,  nor  the  medallion  itfelf  to  remain  in 
<onta£t  with  it  a  fufficient  time  to  alter  its  own  temperature.  The  fuccefs  of  this  procefs 
Spends,  therefore,  on  the  quicknefs  of  the  operation,  and  the  pra£tical  knowledge  of  the 
degree  of  heat  which  the  objeA  of  the  impreflion  can  bear  to  foften  it  widiout  injuring  it  in 
<^er  refpefts:  it  is  necefTary  to  faften  the  medal  to  the  £ice  of  the  fcrew  or  ram,  in  order 
that  it  may  not  touch  the  heated  metal  but  at  the  moment  of  its  fidl. 

Two  filver  medals  ftruck  under  the  magiftraturc  of  Titus  Cavifius,  TriumVir,  Monetarius, 
which  exhibit  the  inftruments  ufed  at  Rome  for  coining;  fuggefted  to  me  the  notion  of  the 
procefs  I  have  been  defcribing.  There  are  two  dies,  one  fuperior  and  the  other  inferior ;  Ac 
lower  die  is  fupported  on  an  anvil,  befide  which  lie  a  hammer  and  pair  of  tongs.  The  form  of 
the  tongs  leave  no  doubt  refpefling  the  ufe  to  which  they  were  applied  ;  they  ferye  to  place 
the  blanks  or  pieces  of  metal  of  the  legal  weight  and  finenefe  between  the  two  dies,  and 
ihefe  blanks  being  fufficiently  heated,  could,  by  a  fingle  ftroke  of  the  hammer,  receive  both 
impreffions.  By  this  defign  the  ancient  art  of  polytypage  is  difplayed.  The  two  Roman 
medals  which  bear  for  their  defign,  the  Dies,  the  Pincers,  die  Anvil,  and  the  Hammer,  were 
ftmck  at  Rome  three  hundred  years  before  the  Chriftian  era,  at  the  epocha  of  the  war  with 
the  Tarentines.  Andrew  Morell,  in  his  work  upon  the  medals  of  the  Roman  Families, 
cxpreffes  himfelf  as  fellows : 

*  The  material  ufed  by  the  celebrated  Taffie,  in  a  fimilar  procefs  of  extreme  delicacy,  was  a  mixtuft  of 
ifulphate  of  lime  (plailler  of  Paris)  and  tripoli.    Sec  PhiloC  Journal,  II.  63,-*N. 

Caput 


RmanMtiaU. — Hahmaklni.  73 

-  -  Caput    Junonis    monetit  falutaris  :   inftrumnta  momtaUat  incus,  maVius^  firctpi,   cum 
vukani  piUo  in  laurea. 

In  helloy  videlicet^  contra  Pjrrbum  it  Tarentin§s^  quum  picunia  deftituinntir  Romania  i$f 

Jcribunt  Jumni  ad  cmparandam  eandem^  votafictjfe^  deam  vero  monmffi  ilUs  utjufticia  armtM 

uterentur ;  fic  enim  pecuniam  iis  nm  defeRuram.    S^uod  monitum  fuum/atutarc  Rmamsfiurk 

agnomina  Montta  Salutaris  inde  yuno  adopta  eft*  Laurea  ad  vi^oriam  illam  oUm  dea  mmifu 

relatam  refpkere  potejl. 

This  Memorandum  is  tranflated  from  the  J.  de  Phyf.  IV.  N.  S.  p.  363. 


aesae 


VI. 

Gbi  the  Prouffis  for  Manufaffuring  Hats^  the  Vfc  of  Machines^  and  other  Obfcffs*    Bf  N.  L% 

ff 

To  Mr.  NICHOLSON. 


In 


Niwcaftk^  lyb  April,  1799. 
SIR, 


addition  to  the  informadon  contained  in  my  former  letters  on  the  fubjed  of  hatwnaktng 
by  engines,  I  would  add  the'houfe  of  Meilrs.  Wells  and  Cbatterton  of  Brenchly,  inKent» 
From  thefe  inftances,  it  would  appear  that  the  queftion  regarding  the  poffibility  of  making; 
hats  by  en^es,  is  clearly  decided  in  the  affirmative.  The  enquiry  now  apparently  is,  how 
fiu*  can  thofe  already  in  ufe  be  fimplified ;  their  principles  accurately  diffdayed  to  the  public^ 
or  their  numbers  encreafed? — ^For  I  believe  the  diredions  given  already  zxc  all  that  aft 
creded* 

The  knowledge  of  hat-making  necellarily  includes  the  practice  of  bowing,  bafoning,  feltingi 
pulling  (thefe  two  laft  are  included  in  the  term  working  ;  that  is,  at  the  plank}|  fo  that  to  a 
hat-maker  the  remainder  of  the  procefles  of  felting  he  would  have  to  inveftigate  (whether  of 
animal  or  vegetable  filaments,  amongft  which  might  be  included  even  the  combing  of  wool, 
the  dreeing  of  flax,  and  the  &brication  of  foldiers'  belts),  would  be  trifling.  For  a  peribn  to 
have  complete  fuccefs  in  the  formation  of  machines,  fuch  as  thofe  in  queftion,  the  fabricator 
Ihould  have  a  comprehenfive  and  determined  mind,  to  bear  with,  and  to  overcome  the  impe- 
diments which  may  be  thrown  in  the  way  by  the  journeymen ;  and  an  enlarged  view  of  che- 
mical, and  efpecially  of  mechanical,  operations,  a  fufficient  portion  of  which,  few  indeed  of 
the  mafters  of  the  prefent  day  poflefs. 

Your  account  of  hat-making  in  your  laft  number,  fuggefted  by  a  viflt  to  the  manufadory 
cf  my  efteemed  friend  Mr.  Collinfon,  will  convince  your  readers  how  far  from  the  truth 
any  former  accounts  are  as  given  to  the  public  in  the  Encyclopedia,  and  alfo  in  the  Uni- 
verial  Magazine  for  the  year  1750,  which  are  all  the  places,  or  nearly  ib,  in  i^ich  it  has 
appeared.  They  will  not  wonder  at  the  few  improvements  regarding  the  introduAion  of 
machines  into  a  bufmefs  which  has,  till  very  lately,  been  hidden  by  the  lahourcd  obfcurity  pf 
prejudiced  and  felf-interefted  manufa£lurers»  Few,  indeed,  yet  think,  that  the  hefl  way  ofim^ 
proving  a  manufacture  is  to  give  it  publicity.    The  progrefs  of  our  cotton  and  woollen  ma* 

Vol.111.— May  1799.  L  nufaftorics 


|4  ^   FafHm$  Olffirvattons  tm  the  Prcciffh 

fiuiatSeries  to  tBeirprefent  ftate,  has  not  probably  been  impeded  by  a  knowledge  of  the  rci- 
ipeAive  btiflnefies  being  developed*  It  is  not  improbable  but  that  the  intervention  of  machine9 
tjas  fufKciendy  repaid  to  the  interefl:<fd  manufa^rer,  any  loTs  attending  that  which  he  might 
ibppoic  to  be  ah  impolitic  difctofure*  We  have  found,  in  the  courfe  of  our  enquiry,  that 
)hachines  are  invented  and  iit  work ;  from  their  fmall  number,  and  the  ftrong  prejudice  exifting 
agalhft  tticm>  eveh  in  the  minds  of  ^e  majority  of  the  majiersy  the  undertaking  muft  be  ac- 
knowledged to  be  only  beginning  to  expand.  Is  it  impiffible  to  accomplifh  it  ?  A  few  years 
ago  the  mafters  in  Lancalhire  generally  fmiled  at  the  attempt,  and  the  houfe  at  Lea  Wood,  In 
Grofi)fevdt..wlis  ridiculed  by,  the  majority,  and  pitied  by  a  few.  But  (ball  ingenuity^  Sir,. 
fabricate  engines  for  other  buHnefles,  and  muft  the  mere  attempt  at  machines  for  this  appear  as 
aaabfurdity  ?  Surely  the  condemnation  of  fuch  attempts  is,,  if  notfutile»  at  leaft  premature.; 
Kideed  it  appear^  to  me  a  ftep  gained,  and  that  no  inconfiderable  one,  to  be  able  publicly  ta 
produce  the  addrefs  of  houfes  who  ufe  engines.  The  contemplation  of  fuch  fads  muft  over- 
dirow  the  qpinioa  of  the  impoi&bility  of  their  ereAiony  that  many  mafters  wifti  to  fpread 
abro2uL 

The  queries  you  fuggeft:  with  regard  to  the  dregSy  are  anIWered  by  my  men  in  the  /bllowir^ 
ifctiner!  The  operation  of  planUng  depending,  in  a  great  degree,  upon  i)ie  acidity  of  die 
l!()QOr,  they  preffer  old  dregs  to  hew,  becaufe  the  older  they  are  the  fourer  they  becoihe.^-^ 
Tlie  fittie  rtafon,.  namely,  Its  acidtiy,  is  given  by  the  felt-makers  for  preferring  old  urine,  as 
ihentiDned  in  a  former  letter,  in  the  boiling  of  felt>4iats  ;  as  to  thofe  no  *  vitriol  is  ufed  in  the 
working.  The  ittp  ought  to  be  thick,  or  the  top  (the  dim)  poured  off.  If  diin  or  new 
tJiey  (poil  the  body  of  the  hats  by  hindering  their  working.  I  may  mention  here,  diat  inr 
confequence  of  the  ftuff^hat-makers  ufing  vitriol,  they  are  obliged  to  have  a  leaden  ketde^ 
wfailft  die  felt  or  woohnakeis  have  only  a  caft-metal  one  ;^  though  wool  hats  feel  much  fofter 
when,  worked  in  a  lead  kettle  dian  a  caft-metal  one,  if  worked  in  each  with  dean  water^ 
(the  reafons  for  this  diflbrence  would  oblige  die  author  of  this).  The  kettle  or  bath  heated 
to  a  lefi  degree  than  diat  you  mention  in  your  memoir,  has  no  power,-  even  though  with 
an  additional  quantity  of  lees  or  vitriol ;  the  hats  are  generally  cb&rved  to  work  ((brink  in) 
as  the  kettle  ^  comes  t6o,*^  that  is,  heats.. 

Before  the  operation  of  planking  is  begun,  the  hat  is  dipped  into  the  boiling  kettle,  and 
allowed  to  lie  upon  die  plank  until  cold  again ;.  diis  is  called  (baking,,  that  is,  being  perfe£Uy 
iaturated' with  the  hot  liquor ;  if  they  are  put  in  too  haftily  in  this  ftate,  for  they  are  then; 
only  bowed  and  bafoned,  they  would  burft  firom  the  edges,,  each,  bat  not  being  fufficiently 
felted  into  the  other*  Vitriol  alone  would  harden  the  hat  too  much ;  the  dregs  keep  it  mellow 
and  thicken  the  body,  for  die  vitriol  alone  eats  or  purges  the  ftujF  too  much  ;.  the  hats  feed 
as  it  were  upoa  the   dregs  f*.     The  pumeymen  tell  me  that  the  dregs  are   to  hold. 

or 
^  The  term  vitriol  appears  to  defignate  ^e  (Uphuric  acid  (^t  of  vitriol)  in  manufadtorics ;  and  not  thfr 
fulphate  of  iron  or  coppec — Nt 

\  Thert  is  a  degree  of  obfcuricy  in  the  defcription,  as  well  as  the  rttionale  of  what  happens  here.    Might 
il  he  con^e&ussdy  that  the  fttipburic  acid  bydiflTolviog  or  difcjigaginga  natural,  mucilage  frum  rhc  face  of  the 

hair,. 


mndi  life  ^h  thi  Manufafforf  if  &A,  y^ 

-or  (31  the  body,  whilft  a.  little  vitriol  dearies  it  of  the   dirt,  &c  that  may  be  tm  'iho 

rabbit  or  other  wools;    Coo  much  vitriol  would  make  the  whole  that  wai  weighed  out 

tp  the  journeymen  work  into  the  hats,  but  by  the  mutual  a&ion  of  the  vitrid  and  the 

dregs,  the  quantity  of  the  firft  being  fmall,  about  a  fmall  wine  giaft  fullt  the  dirt  aad 

the  ftrong  hairs*  get  j)urged  out,  whilft  at  the  £une  time  the  dregs  keep  dieiiat  phmpb .  After 

the  body  is  got  up  to  ascertain  fise,  the  workmen  pat  on  gloves  made  c£  the  Ible  of  a  flioe^ 

to  ihield  their  hands  from  the  vitriol,  to  enable  them  to  work  the  hat  tightert  and  to  bear 

hotter  water.     The  kettle  is  ufually  weakened  before  blocking  the  hats,  left  the.  vitrio| 

ihould  eat  out.  the  dregs.   There  is  only  one  cloth  a(ed  at  the  hurdle^  which  #ith  paper  is 

generally  thought  iuffictent,  and  the  doth  fi^m  its  being  unbleached  and  felled  in  the  wear^ 

anight  naturally  enough  convey  the  idea  of  bdng  dyed  brown.    The  bow  is  beft  made  of 

-afli,  that  it  may  be  heavy  and  fteady  in  working :  it  is  compofed  of  the  ftang  f  or  faandte 

viade  of  the  above  wood :  the  bridge  at  the  finailer  end,  or  that  neareft  the  window,  when  hdd 

in  the  hand  in  the  aA  of  bowing,  is  called  thi  tocky  and  that  at  the  other  end,  which  from  itt 

being  hung  to  balance,  and  being  thicker,  is  the  nearer  to  the  workman's  hand,  n  called  the 

Creech.    After  bowing,  ^lA  previous  to  die  bafoniag,  a  hmrdgmug  Jkin^  that  i9»  a  large  piece 

<tf  Ikin,  about  four  feet  long  and  three  feet  broad,  of  leather  alumed  or  half  turned,  is  preficd 

iipon  die  bat,  to  bring  it  by  an  eafier  gradation  to  a  compaSl  appearance,  after  wUch  it  ti 

4albned,  being  ftill  kept  upon  the  hmrdle.    This  operation,  die  bafening,  derives  its  name 

booi  the  proosis  or  twde  of  wirkingf  being  the  iame  as  that  pra&ifed  upon  a  wool  hat  aAa: 

bowing,  the  laft  being  done  upon  a  piece  of  caft  metid,  four  feet  accds,  of  a  <;ixcular  flupe^ 

<aUed  a  bafon :  the  joining  of  each  bat  is  made  good  here  by  ihufiii^  die  hand^  diat  is,  by 

rubbing  the  eigcs  of  each  bat  folded  over  the  odier  to  estate  the  progreffivo  motion  of  each 

^  the  filaments  in  felting,  and  to  join  the  two  togedier.    Many  journeymen,  to  huny  dii$ 

work,  life  a  quantity  of  vitriol,  and  dien^  C^make  the  nap  rife  and  flow,  they  kill  the  vitriol, 

and  open  the  body  again  by  throwing  in  a  handfiil  or  two  of  oatmeal ;  by  this  means,  thej 

geta  great «any  made,  diougb,  at  the  fiune  dme,  diey  leave  them  quite  grainy  %  from  the  want 

i>f  labour.    This,  in  handling  die  dry  grey  hat  when  made,  tsmff  be  in  part  difcovere^  bttt 

in  part  oi^ly. 

Another  aAvstfage  attending  the  ufe  of  dr^,  whe^er  of  beer,  porter,  or  wine,  is,  that 
«8  die  boiling  in  die  dying  does  iwt  draw  OMtOHioh  of  the  flAucilagip  frame       hat,  wfaendiey 

faaur,  au^  lendor  the  sftioa  of  k)Bng  too  fpeeiy,  dole,  and  inregulsr,  fo  as  not  to  allow  6mt  eidier  for  purfiog 
-ar  lepairing  ^  and  that  the  mUcilaae  of  the  dre^s  prerents  this,  and  has  the  adrant^e  of  being  afterwards 
waihed  out  to  aay  requiMd  -degree  towards  the  tnd  of  the  procefs  ?— N. 


■  .i< 


^Beeaafr:diey  ave  ftraiter  ?*«»Philof.  Journal,  1. 401.  note.— 'N. 

^  Aa  old  noidi-.couiitTy  w<Mrdy.  iigntfylng  a  pole  or  AaC-^N.  r  ' 

i  The  canie,  as  f  prefume,  of  hats  wearing  into  fliioing  or  greafy  fpots.  Thn  was  a  firincipal  defect  <^  the 
cksh  made  under  Booths  patent,  in  wbidi  the  ftaple  ef  the  mw  material,  namely^  cotton,  flax«  or  wool,  was 
fPffOHght  i^tthec,  l?y  an  en^e,  wkfa  iictk  or  no  dependance  jO&  the  fdcuig  property  of  thi  fibre  itielf.— N« 

Lt  come 


76  On  the  iljhoneft  Praiiicis  in  Hat-maUng^  bfc, 

come  to  be  ftiffiuied,  the  dregs  form  a  Ixxiy  withia  the  hat,  fufficiently  ftrong  or  retentive  to 
keep  the  glue  from  coming  through  amongft  the  nap :  vitriol  alone  purges  or  weakens  the 
goods  too  much,  confequendy  half  of  die  quantity  does  better  widi  the  addition  of  dregs, 
and  they  alfi>  allow  the  body  to  be  clofer  from  its  getting  mere  wOrk. 

Let  us  now  examine  the  opportunities  that  journeymen  have  to  fteal  from  their  mafters  ; 
and  probably  diis  review  will  fuggeft  ftill  ftronger  arguments,  for  the  more  general  introduc- 
tion of  machines,  than  has  been  advanced  in  a  former  number.    For  we  fliall  find  that  the 
goodneis  of  die  bodies,  as  well  as  the  quantity  of  beaver  weighed  out  for  the  napping  or 
covering,  which  you  call  the  facing,  may  both  be  gready  impoverifhed,  and  the  mafter,  from 
the  di(honefty  of  the  men,  nearly  ruined  before  he  is  aware :  from  the  mafter  who  weighs  to 
tiie  maker,  and  from  him  after  he  has  got  his  hat  ready  for  the  dreffing,  or  raiiing  the  nap, 
the  beaver  may  be  eafily  ftolen,  and  yet  remain  unknown  to '  the  mafler,  by  the  hats  coming 
in  damped,  though  imperceptible  to  the  hand,  and  of  courfe  weighbg  heavier.    Or  it  may  be 
firid,  by  the  journeymen,  diat  die  hats  were  wider  laid  in  the  bafoning,  and  had  purged  more 
at  plank,  and  of  courfe  lofl  weight    Nay,  die  very  dregs  in  which  it  is  feen  the  hats  are 
worked,  may  increafe  die  weight,  and  even  beating  them  when  dry,  does  not  free  them  entinfy 
from  die  dried  mucikge.    The  cdour  of  the  covering,  or'  beaver,  is  no  infallible  guides  as 
the  journeyman  who  cuts  it,  often  puts  inferior  beaver  into  the  middle  of  a  hood,  lock,  or  ball  of 
beaver,  and  iecretes  a  part  of  the  befl,  which  diey,  as  well  as  the  journeymen  bat-makers,  {ell 
to  the  inferior  mafters  at  a  low  price  ;  detection  in  either  cafe  being  almofl  impoffible.    The 
journeyman  hatter  knows  this,  and  can  fay  the  beaver  was  light  coloured ;  though  that 
article  might  be  very  good,  and  the  covering  appear  light  from  the  hare  wool  or  inferior  beaver 
put  in  by  die  journeyman  hat-maker,  after  having  ftolen  an  equal  weight  of  good  beaver 
(the  value  of  beft  hare's  wool  being  about  i6s.  per  lb.  and  beaver  from  30s.  up  to  6qs.  per  lb.}, 
efpecially  if  backs  of  hare's  wool  be  weighed  into  die  body.    It  is  from  diefe  depredations 
that  die  ufe  (rf"  machines  appears  fo  urg^t :  the  fame  inconveniencies  attend  the  inafter  fur- 
rier or  fkinner  i  he  does  not  examine  each  lock  or  ball  of  beaver  minutely,  fbr  his  dme  will 
:wK  allow  him,  and  any  mixture  of  inferior  beaver  (which  is  very  eafil/ obtained  and  effeded), 
worth,  as  above,  about  30s.  with  the  beft  at  about  6os.  and  a  part  of  that  beft.  ftolen,  will, 
within  a  very  litde  time,  arrive  to  a  large  amount.    Thefe;  and  many  fuch.  Will  demand,  I 
ted  almoft  (aid,  imperioufly,  the  attention  of  the  ingenious  mechanic,  whilft  the  certain  ad^* 
vantage  from  the  above  ftatement^  will  not  be  loft  fight  of  by  the  fiibricator,  inexamimng  the 
arguments  for  and  againft  the  introdudion  of  machines  into  each  bufineft.    To  the  moralift, 
ivho  views  the  di4>Iicity,  the  crimes  and  their  parent  ignorance  of  his  fellows,  die  recoUedion 
of  the  depravity  fo  deeply  impreffed  upon  each  circle  of  journeymenr^from  the  eafe  widi  which 
diefe  thefts  may  be  conduced,  from  the  great  wages  they  receive,  many  in  London  more 
than  30s.  per  vveek,  and  from  their  confirmed  habits  of  debauchery,  confequent  upon  both 
thefe— motives  fufficiendy  ftrong  will  prefent  diemfelves,  to  accelerate  an  enquiry,  at  leaji, 
into  the  impediments,  or  the  advantages,  attending  the  introdu^on  of  engines,  if  they  were 
only  fbr  the  bowing,  hardening,  and  bafoning,  for  then  the  journeymen  would  be  totally 

hindered 


On  Machines.^On  tbe  Mm  $f  Difs.  77 

hindered  from  ftealing ;  or  if  thofe  few  already  in  ufe  were  more  general,  and  probably 
more  fimpliiied,  the  purpofe  might  be  anfwered.  Let  it  then  be  the  pra£lice  of  the  well* 
^ifliers  to  virtue,  to  diminifb,  or  remove  zsbx  2A  poffible^  the  impediments,  whether  arifing 
from  moral  or  other  caufes,  and  vice  will  prefent  to  them  too  ftriking  a  front,  not  to  induce 
them  to  hold  out  the  advantages  in  an  unomamented,  though  decifive  mannen  With  re- 
gard to  flax,  the  objed  of  the  journeymen  in  that  bufinefs,  and  in  that  of  the  wool-combqrs, 
being  the  lame,  that  is,  to  lay  each  filament  in  a  flraight  line  in  certain  proportions,  an  engine 
yrhich  would  accomplifh  the  one,  muft  widi  a  trifling  alteration  effect  the  other.  I  find  in 
the  General  Evening  Poft  for  the  14th  March,  1799,  that  there  is  a  manufa^Qry  eflablifh- 
ing  in  the  neighbourhood  of  Prefcot,  in  Lancafhire,  for  the  purpofe  of  combing  wool  and 
fpinning  Jlax^^How  far  might  a  liint  be  taken  from  this  to  accompliih  the  former? 

Your*s  &c. 

N.  L. 


VII, 
^<ount  of  a  Suhftance  found  in  a  Qay-pit^  and  of  the  Effe^i  of  th^  Men  of  Dlfs 
upon  various  Subflances  immerfid  in  it.  By  Mr.  Benjamin  JFlS£MANy  of  Difs 
in  Norfolk*  With  an  Jnalyfis  of  the  Water  of  the  faid  Mere.  By  CHARLES  HaT'- 
CHETTi  Efq.  F.R.S.  In  a  Letter  to  the  Right  Honourable  Sir  Joseph  BaNKS^  Bart. 
K.  B.  P.R.S.  (Stc.* 


Ti 


HE  fubftance  I  have  inclofed  was  found  near  Difs,  in  a  body  of  day,  from  five  to  eight 
feet  below  the  furfiicc  of  the  foil.  All  the  pieces  I  obierved  laid  nearly  in  a  horizontal 
^ire^on ;  and  varied  in  fize,  from  two  or  three  ounces,  to  as  many  pounds.  The  colour 
i€f  the  fubibuicc,  when  taken  freih  from  the  day-pit^  was  like  that  of  chocolate ;  it  cuts  eafUy^ 
and  has  the  ftriated  appearance  of  rotten  wood.  The  pieces  were  of  no  particular  form ; 
in  general,  they  were  broad  and  flat,  but  I  do  not  recoiled  to  have  met  with  a  piece  that 
,wa8  more  than  two  inches  in  thicknefs :  it  breaks  into  laminae,  between  which  are  the  remains 
of  various  kinds  of  (hells.  The  fpecific  gravity  of  this  fubftance,  dried  in  the  (hade,  is  1.588 ; 
it  burns  freely,  giving  out  a  great  quantity  of  (moke,  with  a  ftrong  fulphureous  (mell. 
By  a  chemical  analyiis,  which  I  cannot  coniider  as  very  accurate,  one  hundred  grains 

^pear  to  contain, 

grains. 
Of  inflammable  matter,  including  the  (mail  quantity  of  water  contained  in  die 

fubftance               -               -  •                 •                •                         •  '^i'S 

Of  mild  calcareous  earth               -  1.                  -•                  -          •     20.0 

Of  iron                -                   -  *  •                 •                    •            .      :  2.0 

t)f  earth  that  appears  to  be  (ilex  •              «              *              «              36.7 


♦  PhifeCTn^f.  1798.  page  567. 


100 

On 


I 

TB  jlceonnt  of  the  Mcrt  tfDifs  U 

On  the  E^eH  of  the  Merc  of  Dtfs  upon  various  Sub/lances^ 

Obferving  (everal  years  ago,  that  flint  ftones  taken  out  of  the  Mere  of  DUs  wcrt  incrufted 
wth  a  metallic  ftain,  I  was  induced  to  make  fome  experiments^  in  order  to  difcover  the 
nature  ec  compoiition  of  this  metallic  fubftance*  Nitrous  acid  readily  removes  it,  diflblving 
a  party  and  leaving  a  .yellowifh  powder,  which,  waflied  and  filtered,  was  found  to  be 
iiilphur.  Vegetable  fixed  alkali  precipitated  from  the  nitrous  acid  a  ferruginous  coloured 
|X>wdery  which  was  iron- 

With  a  view  to  determine  what  length  of  time  was  neceflary  for  the  formation  of  this 
metallic  (lain  upon  flint  ftooes,  or  other  fubdances,  I  inclofed  in  a  bra(s-wire  net  the  follow- 
ing articles-:  flint  ftones,  calcareoMS  ipar»  common  writing  flate,  a  piece  oPconunon  white 
fione  ware,  and  likewife  a  piece  of  black  Wedgwood-pottery.  After  remaining  in  the  water 
from  the  fummer  of  1792,  to  Auguft,  17959  the  flints  and  Wedgwood- ware  had  acquired 
4be  metallic  ftain  in  a  flight  degree,  and  the  flate  had  afllimed  a  ruft  colour ;  the  other 
fubftances  appeared  not  to  be  at  all  altered.  I  was  greatly  furprifed  to  find  the  copper  wire 
that  held  the  net,  furrounded  with  a  metallic  coating  of  a  confiderable  thicknefs;  it  was 
of  a  deep  lead  colour,  and  of  a  granulated  texture.  When  taken  from  the  wire,  and  ground 
in  a  mortar,  it  had  a  black  appearance,  intnfperfed  with  very  hard  fliining  particles.  The 
wire  was  evidently  eroded,  and  this  fubfbmce  depofitcd  in  the  place  of  the  cc^per  that 
was  dectmpofed,  Ibmewhat  fimilar  to  the  decompofition  of  iron  in  cupreous  waters.  By 
repeated  chemical  analyfis  of  this  fubfbmce,  one  hundred  grains  contain,  of  copper,  70; 
of  fulphur,  i6.6i  of  iron,  13.3  grains. 

I  have  never  met  with  an  account  of  the  decompofiti«n  of  copper,  in  waters  impneg- 

tiated  with  iron,  in  any  chemical  wcnrk ;  and,  as  iron  appears  to  have  a  greMer  aflbiity  to  the 

vitriolic  acid  than  copper  has  (as  is  conftandy  evinced  in  the  nci^ibourhood  of  copper 

taines)^  it  appears  an  anomaly  in  chemifby,  that  I  am  not  adept  enough  in  tlw  fciencc  to 

account  for. 

[The  Prefident  and  Council  of  the  Royal  Sodety  thinking  the  effeas  of  th^  water  of  Dift 
Mere  deferving  of  further  inquiry,  defired  Mr.  Wifeman  would' fend  feme  of  the  &id  water, 
ibr  the  purpofe  of  examination.  Mr.  Wifeman  accordingly  fent  a  i)uafitity  of  die  water, 
accompanied  by  die  odier  fubftances  defcribed  in  the  ibUowing  letter  to  the  Ptefident.] 

Sir,  I>if»>  May  29,  17^8. 

As  the  Society  have  expreflfed  a  wifli,  through  Mr.  Frere,  to  have  fome  of  the  water  in 
which  the  copper  wire  was  depofised^  v4iich  Mr.  Frtre,  at  my  requeft,  laid  before  the  Soci^, 
X  have  fent  two  gallons  of  the  water  of  Diis  Mere  (No.  i),  with  a  fmall  quantity  of  copper 
cuttings  (No.  2),  which  laid  in  the  £uBe  water,  a  few  feet  from  the  fid^  and  fix  feet  in 
4eptb,  from  the  yth  of  February,  1797,  to  the  2odi  of  the  prefent  month,  May,  1798*  The 
]ueces  of  copper,  when  laid  in,  weighed  3051  grains ;  when  6iey  were  taken  out,  and  waflieil 
from  die  mud  that  lighdy  adhered  to  them,  prefirving  and  weighing  the  fcaly  matter  that 
casie  oflF,  they  vireighed  2944  grainSj  indicating  a  loft  of  107  grains*    Examijung  the  pieces 

cf 


Norfolk  \  thi  EftSts  of  its  Water,  fie.  79 

•f '(*opper,  the  fame  evening  ibey  were  taken  out  of  the  water,  I  obierved  a  nuoiber  of 
finall  cryftals  formed  upon  fome  of  tbem,  in  the  form  of  pyramids  joined  at  their  bafes  ; 
thefe  cryftals  loft  dieir  fliining  appearance,  by  the  evaporation  of  the  water  of  cryftallization, 
in  the  warmth  of  the  fucceeding  day.  Whether  they  will  be  preferred  in  a  journey  of 
nearly  100  mUe%  is  perhaps  doobtfiil.  No.  3*  cdatains  two  pieces  of  copper,  on  which 
the '^  cryftals.  wece  ipoft  abundant.  No.  4.  contains  a  fmall  quantity  of  the  fubftance  formed 
upon  the  copper,  .that  came  06F  in  wafliing  and  in  weighing  itr 

The  town  of  iDifs  is  principally  fituated  on  the  NNE.  and  £.  fides  of  this  piece  of  water. 
The  land  runs  pretty  fteep  on  the  W.  and  N.  of  it,  to  the  height  of  40  to  50  feet; 
on  the  SE.  the  ground  comes  within  a  few  feet  of  die  level  of  It.  The  foil  of  the  upper 
part  of  the  town  is  a  ftifF  blue  clay  ^  that  of  the  lower  part,  to  the  S£«  a  black  land,  beneath 
which  it  is  a  moor.  The  water  in  the  higher  parts  of  jdie  town  is  good ;  in  the  lower 
parts,  it  is  a  chalybeaXe,  of  which  a  Qiecin^en  is  font  (No.  5.) 

Na  6.  contains  a  guantity^  of  flint  ftones,  taken  from  the  S£.  fide  of  the  Mere,  where 
the  water  is  (hallow ;  many  of  which  are  flrongly  marked  with  the  metallic  fhun,  which 
they  acquire  by  lying  In.this  water  a  few  years* 

The  Mere  contains  about  eight  acres>  and  is  of  various  depths,  to  twenty-four  feet :  from 
its  fituation  with  reipeA  to  the  town>  it  may  naturally  be  fuppofed  to  contain  a  vaft 
quantity.of  miid,  as  it  has  received  the  filt  of  the  ftreets  for  ages.  In  fummer  the  wiater 
turns  green  \  and  the  vegetable  mattec  that  fwins  on  its  furface,  when  expofed  to  the  rays 
of  the  fun,  affords  Vaft  quantities  of  oxygen  ga^  I  cannot  help  confidering  this  procefs 
as  having  a  confiderable  agency  in  the  corrofion,  and  in  the  formation  of  the  metallic  cru{( 
upon  the  copper  depofited  in  this  water.  Some  of  this  vegetable  matter  will  be  found  in  the 
water  fent  to  the  Society. 

1  intend  ta  make  fome  further  experiments  with  different  metallic  fiibftances^  at  different 
parts,  and  at  various  depths  \  but,  as  the  procefs  is  flow,  if  in  the  mean  tinte  you.  Sir,  or 
any  of  the  members  of  the  Society,  will  have  the  goodnefs  to  point  out  any  experiment  you  or 
they  may  wifli  to  have  made,  I  ihall  be  very  glad  to  contribute  all  in  my  power  towards- 
the  illuftradon  of  the  fubjed.. 

I  have  the  honout'  to  be,  huu 

BENJ.  WISEMAN.. 
The  Right  Hon.  Sir  Joseph  Banks,  Bart»< 

ICB.  P.R.S. 


(The 


8o  Analjfis  $/  the  FFaiif  df  thi  Mere  of  Difs. 

■  » 

[Tht  water,  and  odier  fubftances  defcribed  in  the  foregoing  letter,  were  delivered  to  Mr# 
Hatchett,  who  had  been  previoufly  requefted,  by  the  Prefident  and  Council)  to  examine 
them.    The  refult  of  his  examination  is  related  in  the  following  letter  to  die  Prefidentr] 

Analjfis  of  tbi  Water  rfthi  Men  rfDifi^  hy  Charlm  HATCHMTt^  £&[• 
Dear  Sir,  Hammerrmith,  September  i4di,  1791, 

In  confequence  of  the  requeft  which  you  and  the  Council  of  die  Royal  Society  have  done 
me  the  honour  to  make,  diat  I  would  examine  the  water  of*  Difi  Mere^  and  die  other  fub- 
ftances fent  by  Mr.  Wifeman,  I  now  haften  to  acquaint  you  widi  the  refuh  of  my  experi«- 

* 

ments. 

The  fubftances  fent  by  Mr.  Wifeman  are  as  fdbws :  Some  copper-wire,  with  a  blackifh« 
grey  incruftarion.  Water  from  Difs  Mere  (marked  Na  i.)  Copper-cuttings,  covered  with 
a  blackiih  cruft,  fimilar  to  that  on  the  copper* wire  (marked  No.  2.)  Some  cuttings  fimilar 
to  tbofe  above  mentioned  (marked  No.  3.)  The  paper,  No.  4,  contained  fome  of  die  black 
cruft,  detached  from  the  cuttings.  No.  5,  a  quart  botde,  containing  fome  water  from  the 
lower  part  of  the  town  of  DUs,  and  called,  by  Mr.  Wifeman,  a  chalybeate  water.  No.  6^ 
fi>me  flints,  taken  from  the  SE.  fide  of  the  Mere,  where  die  water  is  ibaBow,  and  having,  as 
Mr.  Wifeman  terms  it,  a  metallic  ftain. 

My  firft  experiments  were  made  on  the  incruffation  of  the  copper-wire,  mentioned  in  Mr« 
Wifeman's  firft  letter.  This  incruftation  was  ejiifily  detached  fix>m  the  wire,  and  being 
reduced  to  powder,  was  digefted  widi  nitro-muriatic  acid,  in  a  gende  heat :  a  green  foludon 
was^formed,  and  there  remained  a  refiduum,  of  a  pale  yellow,  which  proved  to  be  fulphur. 

The  folurion  being  diluted  with  two  parts  of  diftilled  water,  was  fuperiaturated  with  pure 
ammoniac,  by  which  a  few  brown  flocculi  of  iron  were  precipitated.  The  fupernatant 
liquor  was  blue ;  and,  being  evaporated,  and  re-difiblved  by  fulphuric  acid,  the  whole  viras 
precipitated  by  a  plate  of.polifhed  iron,  in  the  ftate  of  metallic  copper.  The  component  parts 
of  this  coating  were,  therefore,  copper,  and  a  very  fmall  portion  of  iron  combined  with 
fulphur.  I  could  not  extend  thefe  experiments,  as  the  whole  quantity  of  die  coating  that  I 
was  able  to  colledt,  amounted  only  to  diree  grains  and  a  half  ^. 

The  next  experiments  were  made  on  the  black  cruft  of  Nos.  2,  3,  and  4.  This  I  found 
to  be  exadly  the  fimie  as  that  formed  on  the  copper-wire,  viz,  it  confifted  of  copper 
combined  with  fulphur,  and  a  very  finall  portion  of  iron. 

^  The  copper-wire,  when  the  coating  was  renMved,  was  perfc6tly  flexible,  and  the  furface  did  not  appear 
ainrqual  or  corroded  :  this  is  commonly  the  cafe  under  fuch  circumftances ;  for,  when  fulphur  has  combined 
fuperBcially  with  a  mttal,  the  compound  is  obferved  to  feparate  eafily,  fo  as  to  leave  the  metal  underneath  not 
injured  in  quality,  and  very  little,  if  at  all,  affected  in  appearance.  Thofe  who  diminilli  Giver  coin,  make  ufe  of 
the  following  method  :  They  expofe  the  coin  to  the  fumes  of  burning  fulphur,  by  which  a  black  cruft  of 
fulphurated  filver  is  foon  formed,  which,  by  a  flight  but  quick  blow,  comes  off  like  a  fcalc,  leaving  the  coin  fo 
Utile  affected,  that  the  operation  may  foroctiroes  be  repeated  twice  or  thrice,  without  much  hazaid  of  deicaion, 
f  the  coin  has  a  bold  imprefldoa, 

I  next 


jlnatyfis  of  ibi  fFater  tf  thi  Afer  of  *D^^  tt 

I  next  examined  the  water  of  Oifs  Mere  (No.  i»)iand  I  was  at  length  led  on,  ftep  by  ftep, 
to  make  a  regular  analyfis  of  the  fixed  ingredients.  Before  I  made  die  analjKis,  I  examined 
this  water  with  certain  re-agents^  and  remarked  the  following  properties.  i»  The  water  of 
Difs  Mere  has  a  yellowifli  tinge,  and  the  flavour  is  rathec  (aline  \  but  it  has  not  any  perceptible 
odour.  2.  Prui&ate  of  pptaQi  did  not  produce  any  efie£l.  3»  Acetite  of  lead  produced  a 
flight  white  precipitate.  4.  Nitrate  of  filver  formed  one  very  copious.  5.  Tindure  of  galls 
had  not  any  eiFed.  ,  6.  Muriate  of  barjrtes  caufed  a  flight  precipitate.  7.  Ammoniac,  pot- 
afli,  and  oxalic  acid,  feverally  produced  precipitates,^  when  added  to  different  portions  of  this 
water. 

Anahjfes. 

A.  Three  hundred  cubic  inches  of  the  water,  by  a  gentle  evaporation,  left  a  pak  browiv 
fcaly  fubftance,  which  weighed  58  grains.     B.  Thefe  58  grains  were  digefled  in  alcohol,. 
widiout   heat,  during   24  hours,  and  afforded  a  foiudon,  which,  by  evaporation,  yielded 
muriate  of  lime,  flightly  tinged  by  marihy  extra^  1 8  grains.     C  Six  ounces  of  cliftilled 
water  were  then  poured  on  the  refiduum,  and,  with  repeated  ftirring,  remained  during  24 
hours. ,  By  evaporation,  this  afforded  muriate  of  foda,  with  a  very  (mall  portion  of  fiilphate 
•of  foda ;  in  all,  10  grains.    D.  What  remained  was  boiled  in  800  parts  of  diftilled  water,  and' 
,the  iblution  being  evapcN^ted,  left  of  felenite  1.70  grains.    £•  The  imdiflblved  portion  now 
weighed  25  grains,  and  was  digefted  with  diluted  muriatic  acid :   a  great  part  was  diflblved, 
with  much  eflfervefcence,  and,  being  filtrated,  afforded,  by  ammoniac,  of  ahimine  1.50  gr.- 
•From  this  I  afterwards  feparated  a  very  minute  quantity  of  iron,  by  means  of  pruffiate  of  pot- 
afli.     F.  Carbonate  of  foda  was  dien  added  to  the  liquor,  and  precipitated  carbonate  of  lime* 
20  grains.     G.  The  infoluble  refiduum  weijghed  3.50  gr.  ^  and  proved  to  be  principally  car- 
bon (produced  by  decompoied  vegetable  matter},,  with  a  very  fmall  quantity  of  filiceous  earth.- 
The  refult  of- this  analyfis  wasy  therefore, 

B.  Muriate  of  lime  --.-.- 

C.  Muriate  of  foda,  with  a  very  imall  portion  of  fulphate  of  foda 

D.  Selenite  --..-- 

E.  Alumine,  with  a  portion  of  iron  too  fmall  to  be  eftimated 

F.  Carbonate  of  lime        -  -  -  -  - 

G.  Carbon,  with  a  little  filiceous  earth  »  -  . 

Loft 


18 

10 

I 

70 

r 

SO 

20 

3  5<» 

54  70 
3  30 

58 

0 

It  b  worthy  of  notice,  that  the  iron  prefent  was  in  fo  very  fmall  a  quantity  as  not  to-  be  db-- 
teOedby  any  teft,  till  it  had  been  feparated  in  conjundion  with  the  alumine. 

Tlie  water.  No.  5,  firom  Mr.  Wifeman*s  account,  does  not  appear  to  have  been  concerned^ 
Voju  IIL— Mav  1799.  M  in: 


12  iHveftigation  ofthi  Eff$R%  produced  vpm 

in  producing  the  eiFe&s  v^hich  he  has  obferved,  and  the  quantity  was  too  fmall  to  be  Tub- 
je6lcd  to  a  regular  analyfis;  I  noted,  however,  what  follows  : 

I.  It  has  a  very  ftrong  hepatic  flavour  and  fmell.  2.  A  plate  of  poliOied  filver,  put  into  it, 
became  black  in  a  few  hours.  3.  It  became  faintly  bluifli  with  prufliate  of  pota(h,  after 
ftanding  five  or  fix  hours.  4.  Tin£ture  of  galls  produced  a  faint  purple  cl6ud«  5.  SoIu« 
tion  of  acetite  of  lead  afforded  a  brown  precipitate.     6.  Nitrate  of  filver  produced  the  &me. 

7.  Potafh,  and  ammoniac  caufed  a  precipitate ;  but  that  of  the  former  was  the  mofl  copious. 

8.  Oxalic  acid  produced  a  precipitate.     9.    Muriate  of  barytes  had  alfo  a  flight  effedl. 

The  water,  No.  5,  cannot,  therefore,  be  confidered  as  a  chalybeate  (the  quantity  of  iron 
contained  in  it  being  fcarcely  perceptible) ;  but  it  appears  to  be  a  water  containing  fome 
hepatic  gas,  together  with  fubflances  fimilar  to  thofe  contained  in  No.  i.  From  the  above 
experiments  it  is  evident,  that  the  water,  Na  i,  does  not  contain  any  of  the  component  parts 
of  the  cruft  formed  on  the  copper- wire  and  cuttings,  although  it  is  certain  diat  the  incruftadon 
took  place  during  the  immerflon  of  thofe  bodies ;  but,  before  I  mention  my  ideas  on  this  fub- 
je£l,  I  (hall  give  an  account  of  fome  experiments  made  on  the  flints.  No.  6.  Thefe  were 
coated  with  yellowifh  fhining  fubftance,  which  appeared  to  me  to  be  pyrites ;  and,  as  the 
flints  could  not  have  contributed  any  metallic  fubftance  to  form  this  coating,  I  was  enabled 
by  their  means  to  afcertain,  whether  the  copper  of  the  cruft,  formed  on  die  wire  and  cuttings, 
liad  been  furniflied  hy  the  pieces  of  copper,  or  by  any  thing  in  the  vicinity  of  the  wat^r. 

1.  I  poured  nitro-^muriatic  acid  on  fome  of  the  flints,  in  a  matrafs,  fo  as  completely  to  cover 
them.  The  coating  was  rapidly  difTolved,  with  much  eflFervefcence ;  andy  when  the  flints 
appeared  perfedly  uncoated,  and  in  their  ufual  ftate,  I  decanted  the  liquor. 

2.  A  yellow  matter  fubflded,  which  proved  to  be  fulphur. 

3.  Prufliate  of  potafh  produced  PrnfSan  blue ;  and  the  remaining  part  of  the  folution, 
being  fuperfaturated  with  ammoniac,- afforded  an  ochraceous  precipitate  of  iron.  The  fupei^ 
natant  liquor  did  not  become  blue,  as  when  copper  is  prefent,  nor  was  the  fmallefl  trace  of  it 
afforded  by  evaporation. 

Martial  pyrites  is,  therefore,  the  only  fuUbnce  depofited  on  bodies  immerfed  in  the  water 
of  Difs  Mere ;  and  the  copper  of  the  crufl-,  formed  on  the  wire  and  cuttings,  was  furni(hed 
by  thofe  bodies. 

It  is  proved  by  the  analyfis,  that  the  water  of  Difs  Mere  does  not  hold,  in  folution,  any 
fulphur,  and  fcarcely  any  iron  ;  it  has  not,  therefore,  been  concerned  in  forming  the  pyrites  ; 
but  it  appears  to  me,  that  the  pyritical  matter  is  formed  in  the  mud  and  filth  of  the  Mere; 
for  Mr.  Wifeman  fays  in  his  letter,  that  «*  the  Mere  has  received  the  filt  of  the  ftreet  for 
ages."  Now  it  is  a  well-known  faft,  that  fulphur  is  continually  formed,  or  rather  liberated, 
from  putrefying  animal  and  vegetable  matter,  in  common -fewers,  public  ditches,  houfes  of 
office,  &c.  &c. ;  and  this  moft  probably  has  been  the  cafe  at  Difs.  Moreover,  if  fulphur 
thus  formed  fhould  meet  with  filver,  copper,  or  iron,  it  will  combine  with  diem,  unlefs  the 
latter  fhould  be  previoufly  oxydated.  The  fulphur  has,  therefore,  in  the  prefent  cafe,  met 
with  iron,  in,  or  approaching,  the  metallic  ftate,  and  has  formed  pyrites ;  which  (whilft  in 

a  minutely 


V. 


■'y 


various  Bodies  imnurfed  in  fti  fFater  ofDifs  Men.  Sj 

a  minutely  divided  ftate,  or  progreffively  during  formation)  has  been  depofited  on  bodies^, 
iuch  as  the  flints  when  in  contact  with  the  mud.  Buc  an  excefs  of  fulphur  appears  to  be  pre- 
fent ;  for,  when  copper  is  put  into  the  Mere,  the  fulphur  readily  combines  with  it  \  and,  at 
the  fame  time,  a  dnali  portion  of  iron  appears  to  unite  with  the  compound  of  copper  and 
fulphur,  poiSbly  by  the  mere  mechanical  Z&  of  precipitation. 

The  incruftation  on  the  copper  wire  and  cuttings  is,  in  every  property,  fimilar  to  that 
rare  fpecies  of  copper  ore,,  called  by  the  Germans  kupftr  fchwUrtxe  (cuprum  ochraceum 
nigrum)  \  and  I  confider  it  as  abfolutely  the  (ame.  In  re^e£t  to  the  martial  pyrites  on  the 
flints^  there  can  be  no  heiitation  ;  and,  as  in  thefe  two  inftances,  there  were  evident  proofs 
of  the  recent  formation  of  ores  in  the  humid  way,  I  was  defirous  to  afcertain  the  efFe£b  on 
iilver.  I  therefore  wrote  to  Mr.  Wifeman,  to  requeft  that  he  would  take  the  trouble  to* 
make  the  experiment ;  and  received  from  him  the  following  anfwer,  accompanied  by  tha 
ipecimens. 

««  Sir,  **  D«fs,  8ih  of  September,  1798. 

"  Immediately  upon  the  receipt  of  ^ur  letter  (27th  July),  I  laid  (bme  filver  plate,  and! 
filver  wire,  into  the  Mere;  the  whole  weighed  235.6  gr,  I  took  it  out  on  Thurfday 
laft  (September  6th).,  and,  after  cleaning  it  carefully  from  mud  and  weeds,  I  find  it  weighs 
'  142.?  gr. ;  an  mcreafe  of  7.2  gr.  The  filver  plate  you  will  find'  much  tarnifhed^  in  fome 
parts  almoft  black ;  the  wire  is  in  many  places  fairly  incrufted,  which  crufl,  upon  the  prefTure 
of  the  fingers,  comes  ofF  in  thin  fcales.  The  whole  appearance  of  the  filver  flrongly 
indicates  the  prefencc  of  fulphur,  which  I  have  no  doubt  abounds  in  every  part  of  the 
Mere.  The  peculiar  finell  of  the  mud  gives  me  reafbn  to  fuppofe,  that  a  great  deal*  of 
hepatic  air  is  produced ;  which,  probably,  uniting  with  the.  iron,  hei(^  in*  folution  in  the 
urater  of  the  Mere^  may  account  for  the  martial  pyrites  found  on  the  flints.  By  what  affinity- 
the  copper  wire,  laid  in  this  water,  is  attacked,  I  am  not  chemifl  enough  to  determine. 

^  I  have  begun  a  fet  of  experiments,  with  the  view  of  producing  the  fame  efFe<Ss  upoa 
copper  wire  by  artificial  means;  but  whether  I  fhall  fucceed,  I  am  not  at  able  prefent  to  fay. 

•••I  am,  StQ. 

*«'  BENJ.  WISEMAN." 

P.  S.  By  experiments  I  have  lately  made,  I  findhepatFc  gas  precipitates  carbonate  of  iron 
in  the  form  of  a  black  flocculent  matter ;  71  parts  of  which  are  iron,  and  29  fulphur. 

The  filver  plate  I  found  (as  Mr.  Wifeman  has  mentioned)  much  tarnifhed,  and  in  many 
places  almoft  black,  bull  could  not  detach  any  part  of  it.  I  fucceeded  better  with  the  wire^> 
and  colle^ed  a  fmall  portion  of  a  black  fcaly  fubflance^  which^  as  fiu*  as  the  fmallnefs  of 
the  quantity  would  allow  it  to  be  afcertained,  was  fulphuret  of  filver ;  and  was  fimilar,  in' 
«very  refpe£l,  to  the  fulphurated  or  vitreous  ore  of  filver,  called  by  the  Germans  glafertz.. 
This  tStSt  on  the  filver  was  to  be  expe£ted  ;  and  I  recollect  to  have  read,  not  many  month  ss 
ago^  in.  one  of  the  foreign  journals^  that  Mr.  Prouft  had  examined  an  incruftation,  of  a 

Mz  darkL 


94  f^mafhn  9/ Pfriut^On  Ph^/^Uruu 

dirk  grey  colour,  fonned  in  the  courfe  of  z  very  long  time,  on  fooie  filirer  linages,  in  % 
church  at  (I  believe)  Seville.  Tliis  incruftatibn  he  found  to  be  a  compound  of  filver  widi 
fulphur,  or,  in  other  words,  vitreous  filver  ore.  The  fame  principle  is  die  caufe  of  die 
tarnifh  which  filver  plate  contra^  with  fo  much  esdie,  particularly  in  great  cities }  for  this 
tarnifh  is  principally  a  commencement  of  mineralization  on  die  furface,  produced  by  die 
fulphureous  and  hepatic  vapours  difperfed  throughout  the  atmofphere,  in  fuch  places. 

To  Mr.  Wi&man's  obfervations  we  are  much  indebted,  as  they  make  known  the 
recent  and  daily  formation  of  martial  pyrites,  and  other  ores,  under  certain  circumftances. 
It  is  not  to  be  fuppofed  that  fuch  efFc£b  are  local,  or  peculiar  to  Difs  Mere ;  on  die 
contrary,  there  is  rcafon  to  believe  that  fimilar  effeds,  on  a  larger  fcale,  have  been,  and  are 
now,  daily  produced  in  many  places.  The  pyrites  in  coal  mines  have,  probably,  in  great 
meafure  thus  originated.  The  pyritical  wood  aUb  may  thus  have  been  produced ;  and,  by 
the  fubfequent  lo(s  of  fulphur,  and  oxydation  of  the  iron,  this  pyridcal  wood  appears  to  have  form^ 
ed  the  wood-like  iron  ore  which  is  found  in  many  parts,  and  particularly  in  the  mines  on  the 
river  Jenifei,  in  Siberia.  In  (hort,  when  the  extenfive^uence  of  pyrites  in  the  mineral  king- 
dom, caufed  by  the  numerous  modif^cadons  of  it,  in  the  wayof  compofidon  and  decompofidon^ 
is  confidercd,  every  thing  which  refleds  light  on  its  formation  becomes  intereftiiig  \  and  I 
cannot  but  regard  as  fuch,  the  effei^s  which  Mr*  Wifeman  Ivas  obferved  in  the  Mere 
<X  Difs. 

With  great  refped,  I  remain,  &c. 

CHARLES  HATCHETT. 
The  Right  Hon.  Sir  Joseph  Banks,  Bart. 

K.B.  P.R.S.  &c. 


VIII. 
Abjlraef  rf  ExpirimenU  and  Obftrvations  en  tbi  internal  Vfi  rf  Pbt/^hms.     By  AlbSQIJ* 

SUS  LMJtOZf  Pro/effbr  at  the  School  9/  Afedkine  in  Paris*. 


,T, 


HE  internal  adminidration  of  phofphoms  in  fuch  dileafes  as  exhauft  the  vital 
powers,  appears  to  give  a  certain  degree  of  aftivity  to  the  eneigy  of  life»  and  aflTord  fpirits 
to  the  patient  ¥athout  raifing  the  pulfe  in  die  iame  proportion.  The  author  relates  feveral 
cafes  in  his  own  pradice^  Among  others  is  the  following.  He  was  called  to  a  woman  at 
the  point  of  death,  who  was  exhaufted  with  wtakhefi  after  duree  years^  ficlmefi.  He  yielded 
to  the  preffing  intreades  gf  her  hufband,  who  eameftly  defired  that  be  wbiM  prefkribe 

r 

fomething.  He  compofed  a  draught  confiiling  of  fyrup  diluted  widi  wat^y  which'  had 
renuuned  upon  the  fticks  of  phofphoms.  She  was  much  better  the  fiSoiiiiag  day,  and 
continued  to  recover  for  feveral  days  afterVWds.  SM  £ed  about  fixteen  dajrs  fubfequent 
to  this  prefcription. 

^  Fiom  the  bulletiA  of  the  Sociic^  Philmnaduqut,  copied  into  the  jounud  de  Fbrfi^e,  IV.  N.  S.  40s. 

2.  He 


Oufhi  intifW^Vfe  and  EfeSs  ffPhnfphoYuU  IS^ 

2.  He  himfelf  had,  as  he  exprcffes  it,  the  imprudence  to  take  two  or  three  grains  of  folid 
phofphorus,  *tii[^ly  united  with  Acriaca.  The  confequenccs  were  dreadfully  alarming.  His 
firft  fcnfiition  W3,s  'that  of  a  burning  heat  in  the  region  of  the  ftomach,  which  organ  appeared 
to  him  to  be  filled  with  gas,  and  even  emitted  elaftic  fluid  by  the  mouth.  In  this  (hocking 
ftate  of  torment,  he  endeavoured  but  in  vain,  to  caufe  himfelf  to  vomit,  and  found  no  relief 
but  by  drinking  cold  water  from  time  to  time.  His  pains,  were,  at  length  affuaged ;  but 
Ae  following  day  an  aftonifliing  mufcular  force  was  developed  through  the  whole  habit, 
with  an  almoft  irrefiftible  difpofition  to  exert  that  force.  The  efFeft  of  the  medicine  at  length 
terminated  after  a  violent  priapifm. 

3«  In  many  circumftances  the  author  has  employed,  or  continues  to  prefcribe,  phofphorus 
internally,  with  the  greateft  fuccefs,  to  reftore  and  eftablifh  the  forces  of  young  perfons 
exhaufted  by  too  frequent  fenfual  indulgence.  He  defcribes  the  procefe  by  which  he 
divides  the  phofphorus  into  very  fmall  particles.  He  agitates  the  phofphorus  in  a  bottle  filled 
with  boiling  water,  by  Which  means  it  becomes  divided  into  globules ;  and  by  afterwards 
continuing  to  agitate  the  bottle  beneath  cold  water,  be  obtains  a  kind  of  precipitate  or  very 
£ne  powder  of  phofphorus,  which  he  levigates  gently  with  a  fmall  quantity  of  oil  and  fugar, 
and  dilutes  the  whole  m  the  yolk  of  an  egg,  to  be  ufed  as  a  loboch.  By  the  help  of  this 
medicine  he  has  performed  cures,  remarkable  for  the  ipeedy  reftoration  of  ftrength  obtained 
by  his  patients. 

4.  In  malignant  fevers,  the  internal  ufe  of  phofphorus,  to  ftop  the  progreft>«f  gangrene, 
fucceeded  beyond  all  hope.     The  author  relates  feveral  inftances. 

5.  Pelletier  related  to  him,  that  having  negle<^ed  a  portkm  of  phofphorus  in  a  copper  bafon, 
tiie  metal  was  oxyded,  and  remained  fufpended  in  the  water ;  that  having,  by  accident, 
thrown  this  water  into  a  fmall  court  where  ducks  were  kept,  tkofe  birds  drank  of  it,  and 
every  one  died ;  but  the  male  covered  the  females  to  the  laft  inflant  of  his  life :  an  obfervation 
which  agrees  with  the  h&  of  the  priapifm  which  the  author  experienced^ 

6.  The  author  relates  a  fa£i,  which  (hews  die  aftonUhing  divifibility  of  phofphoras.  Hair- 
ing ufed,  in  the  treatment  of  a  patient,  certain  pills,  into  the  compofition  of  wfaidi  a  quantity 
of  phofphorus,  amounting  at  moft  to  one-fourth  part  of  a  grain,  entered  ;  he  feuad  upon 
theoccafion  of  opening  the  body,  that  all  the  internal  parts  were  luminous,  and  even  die  hands 
of  die  operator,  diough  vira(hed  and  well  dried,  preferved  the  phc^phoric  lij^  far  a  confider- 
able  dme. 

7.  The  phofphoric  acid  ufed  as  a  lemonade^  proved  very  advantageous  m  the  cure  ct  ^ 
great  number  of  diibrders* 

8*  Leroi  affirms,  diaC  having  oxyded  iron  with  phofphorus,  he  obtained  a  white  oxyd^ 
fcarcely  reducible  by  the  ordinary  methods,  whidihe  thinks  may  be  advaatageoufly  fubftituted 
inftead  of  white  lead,  in  die  arts,  particularly  m  oil  and  enamel  paintings.  This  wbhe  oxyd 
of  iron  produced  a  very  ftrong  nau(ea  in  the  audior,  who  ventured  to  place  a  particle  upon 
his  tongue.  He  does  mot  hefitate  to  confider  it  as  a  dreadful  poifon.  He  could  not  reduce  it 
.but  by  fixed  alkali  and  phoijpboric  ghfs» 

g.  The 


• 


16  Concerning  tbi  Figurt  of  a  BoiUrfir  Steam^ingines* 

9*  The  author  affirms,  that  by  the  afliftance  of  phofphorus  he  has  decompofed  and  fepa^- 
rated  the  fulphuric,  muriatic,  and  nitrous  acids,  from  their  bafes  -,  and  that  he  has  tranfmuted 
the  earths  by  means  of  phofphoric  acid,  fo  as  to  obtain  confiderable  quantities  of  magnefia 
from  calcareous  earth.  And  he  declares,  that  by  his  operations  upon  phofphorus  he  has  ob- 
tained procefTes,  by  means  of  which  he  has  eiFeded  the  frit  of  rubies  *f  the  fufion  of 
emeralds,  and  vitrification  of  mercury. 


IX. 

Letter  of  Enquiry  rejpe^ing  the  proper  Form  of  a  Boiler  for  Sttam  Engines. 

To  Mr.  Nicholson. 
Sir,  17th  April,  1799, 


I 


AM  about  to  ereSt  a  large  fteam-engine,  but  am  in  doubt  of  the  proper  conftru£lion  of 
boilers.    Thofe  which  I  ufe  at  prefent,  appear  to  me  very  improper  for  raifing  the  greateft 
quantity  of  fteam  with  the  leaft  fiiel.    The  form,  however,  has  been  in  repute  for  10  or  15 
years  paft.     My  boilers  are  8  or  9  feet  in  height,  4  to  5  in  breadth,  and  9  feet  in  length* 
Through  the  middle  lengthways  is  a  flue  of  iron  plates,  as  is  the  reft  of  the  boiler,  and  the 
water  muft  always  cover  this  flue,  confequently  ftand  5  to  6  feet  deep  in  the  boiler.    This  flue, 
with  die  flues  on  the  outfide  of  the  boiler  running  parallel  to  it,  is  iaid  to  accelerate  greatly 
the  production  of  fleam,  and  to  have  the  fame  effedt  as  a  great  fire-place  below  a  broad 
and  (hallow  boiler.    But  I  have  often  obferved,  that  a  flame  paffing  through  any  flue  in 
which  there  are  no  obftru6ltons,  to  make  the  flame  reverberate,  commum*^cates  very  little  heat 
to  the  fide  in  proportion  to  the  fuel  wafM.     And,  in  my  boilers,  while  the  foiu-  fides  of  the. 
internal  flue  have  been  perfedly  entire,  the  end  of  the  flue  where  it  turns  ofl^  has  been  burnt 
through.    If  this  internal  flue  communicates  dierefore  little  heat  to  the  furrounding  water, 
Ac  greateft  part  of  the  fteam  raifed,  muft  be  from  the  loweft  ftratum  of  water  in  contaA 
with  the  bottom  of  the  boiler ;  but  by  the  confbii^on  this  ftratum  has  to  overcome  a  column 
of  5  or  6  feet  of  water.      Hence  I  conclude,  that  the  conftru£tion  of  boilers  to  raiie  the 
greateft  quantity  of  fleam  with  the  leaft  fiiel  fhould  be  fliallow,  and  flues  placed  below^ 
with  obftrudions  to  force  the  flame  agauift  the  bottom.    Engineers  objeSt  to  Aich  a  form 
on  account  of  the  danger  of  burning  the  boiler,  by  inattention  in  the  engine-keeper,  in 
not  fupplying  water  enough  always  to  cover  the  parts  aded  on  by  the  fi^re,  and  the  difficulty 
of  preferving  a  highly  elaftic  fteam.     But  furely  it  is  eafy  to  proportion  the  fupply  of 
water  to  the  evaporation,  and  a  contrivance  fimihr  to  a  ball-cock  in   water-cifterns  would 
obviate  the  firft  objection.     By  forming  the  crown  of  the  boiler  with  a  flat  arch  not 
far  removed  from  die  fur&ce  of  the  water,  I  can  diicover  no  reafon  why  fteam  as  elaftic 
as  in  the  prefent  form  of  boilers  may  not  be  always  at  command. 

You  will  oblige  siany  of  your  readers  by  giving  your  opinion  on  Ai%  ftibjed,  fo  Interefting 

to  die  arts. 

I  am,  &c. 

A.  MINER.  Wt 

•  V  otire  la  frit*  des  rkiii.    An  ezprcRion  which  I  do  not  uaderftaad.— N.  * 

'^  Tilt 


Pnduflhn  #/  Sii4im  under  Jlffirent  Grcumjlancet.  if 

.  Th*s  letter  arrived  too  late  in  the  mdndi  for  me  to  give  an  abridgement  of  fo  much  of  Count 
Rumford's  excellent  *^Effay  VI.  On  the  Management  of  Fire  and  the  Ecommy  of  Fuel,  as  is  appli- 
cable to  the  enquiry  it  contains.     If  I  can  have  the  Count's  permifEon  to  copy  fome  of  the 
engravings  (of  which  I  have  no  doubt),  this  fhall  appear  next  month.     In  the  mean  time  I 
muil  refer  niy  correfpondent  to  die  eflfay  of  the  lame  author,  on  the  propagation  of  heat  in 
fluids,  of  which  accounts  are  given  in  this  Journal,  vol.  I.  289.  341.  563.     He  will  there 
oUerve  that  fluids  communicate  no  perceptible  quantity  of  their  heat  in  any  other  way,  than 
by  the  a(^ual  contaf):  with  folids,  produced  by  the  relative  motions  of  their  parts  ;  and  from 
this  leading  bBt  it  will  follow,  that  the  quantity  of  heat  communicated  to  the  boiler  from  a 
given  fire,  will  be  governed  by  the  arrangements  for  caufmg  the  greateft  number  of  particles 
of  heated  air  and  flame  to  come  into  conta(^  with  it,  and  for  preventing  the  heat  being  con- 
ducted off.     It  is  very  obvious,  that  the  boiler  he  defcribes  is  not  calculated  to  abforb  all  the 
heat,  but  that  from  the  (hortnefs  and  ftraitnefs  of  the  channes,  thofe  heated  fluids  muft  pafs 
off  at  a  very  high  temperature,  to  the  confcquent  diminution  of  efie£l  and  wafte  of  fuel.    I 
do  not  here  minutely  enquire  what  may  be  the  bed:  figure  for  a  fteam^^boiler  of  iron^  at  the 
ufual  ftrength  of  lolb.  to  the  fquare  foot,  to  fuftain  an  internal  prefflure  of  betwe^  one-fixth 
and  one-fourth  of  an  atmofphere,  becaufe  every  one  is  aware  of  the  advantages  of  a  figure 
approaching  to  the  fpherical  form,  and  becaufe  other  figures  of  much  lefs  ftrength  will  hold 
very  well  under  the  circumftances  above-mentioned. 

The  principal  queftion  exclufive  of  the  faving  of  heat,  hereafter  to  be  confidered,  b  to  de« 
termine  how  far  the  depth  or  fhallownefs  of  the  water,  in  the  boiler,  may  influence  the  produo* 
tion  of  fteam. 

If  the  parts  of  a  mafs  of  water  could  preferve  the  iame  relative  pofitions,  during  the  appli* 
cation  of  heat,  and  this  heat  were  applied  at  the  bottom  linder  a  depth  of  fix  feet,  it  would 
depend  upon  the  conducing  power  of  the  fluid,  whether  the  upper  or  lower  parts  (hould 
give  off  the  greateft  quantity  of  fteam  in  a  given  time.  If  the  lower  parts  were  to  afford  the 
greateft  product,  this  would  be  done  under  a  greater  preflure  and  at  a  higher  temperature ; 
fo  that  it  would  become  an  objed  of  experimental  refearch,  whether  fuch  fteam,  by  giving  out 
heat  to  the  fuperincumbent  water,  through  which  it  muft  rife,  and  rendering  a  portion  of  it 
elaftic,  might  not  be  as  efFedual  in  its  ultimate  operation,  as  if  the  heat  had  been  employed 
upon  a  fltallower  mafs.  But  the  h&  is,  that  the  parts  of  fluids  do  not  preferve  their  relative 
fituation  during  the  application  of  heat :  the  water  in  the  boiler  will  expand  and  rife  with 
rapidity  as  it  acquires  heat,  and,  in  all  probability  (for  in  this  cafe  alfo  we  are  in  want  of  fa6l$), 
will  give  ofF  a  much  larger  portion  of  fteam  while  it  circulates  near  the  upper  furface, 
and  is  lofing  its  elevated  temperature,  than  while  it  glides  along  the  bottom  in  the  a£l  of  re- 
ceiving heat.  From  this  view  of  the  fubje^  though  I  am  difpofed  on  the  whole  to  con- 
clude that  the  (hallower  mafs  of  water  may,  in  many  refpeiSs,  deferve  the  preference,  yet  I 
doubt  whether  the  difference  arifing  from  mere  preflure  be  an  obje£i  of  any  confiderable  im- 
portance*   As  the  medium  temperature  of  the  whole  mafs  of  a  fluid,  heated  from  beneath, 

*  Publifhed  before  the  commencement  of  this  Journal. 

is 


8S  BoiUrfir  Steam.'^^il  JFurtroie. 

is  higher  when  dsep  than  when  fhallowy  it  is  found  to  be  of  fome  omfequence  in  the  diftlN 
lation  of  fermented  liquors,  that  the  charge  fhould  not  be  deep.  But  this  appears  to  be  lefs 
on  account  of  any  fuppofed  rapidity  of  evaporation,  than  becaufe  the  flavour  of  the  produS; 
may  be  altered,  by  fuch  increafe  of  temperature. 

To  afford  a  regular  fupply  of  water  to  the  boiler,  without  depending  upon  the  engine-keeper, 
IS  certainly  an  objcft  of  no  difficulty,  and  is  actually  done  in  many  fteam-engines,  by  means 
fimilar  to  that  tiggefted  ]jy  my  correfpondent.  In  Mr.  Kier's  engine,  defcribed  in  diis 
Journal,  I.  422.  the  water  is  admitted  through  a  valve,  kept  (hut  by  a  float,  which  falls  as 
the  water  fubfides  by  evaporation.  On  which  particular,  I  may  here  add,  that  the  body  im- 
merfed  in  the  water  is  not  a  fimple  float,  but  a. piece  of  £tone  that  hai^  from  the  valve, 
which  is  affifted  in .  its  tendency  upwards  by  a  balance-lever  and  counter  weight.  When  the 
ftone  is  immerfed  to  a  certain  depth,  the  weight  attached  to  the  lever  predominates,  but  when 
the  water  fells  below  that  depth,  the  flone  exerts  mor€  of  its  gravity,  and  keq>s  the  valve  down> 
till  the  requifite  fupply  of  hot  water  has  flowed  in.  ^ 

a  I/?  Jpril,  1799. 

W.N. 


Ml 


X. 

Vefcriftm  of  the  Furnace  for  twutrting  Bar-irtn.  into  Steel,  ly  Mr.  JOSMPH  COLLISR*. 


T 


H  £  furnaces  for  making  fteel  are  conical  buildings,  about  the  middle  of  which  are  two 
troughs  of  brick,  or  iire-ftone,  which  will  hold  about  four  tons  of  iron  in  the  bar.  At  the 
bottom  is  a  long  grate  for  fire.  The  fteel  furnace,, however,  is  not  well  adapted  with 
defcription.  I  fhall,  therefore,  avail  myfclf  of>n  accurate  account,  which  v^as  conununicateil 
to  me  by  a  gentleman  conver(ant  with  the  maoufaiSure. 

A  layer  of  charcoaUduft  is  put  upon  the  bottom  of  the  trough^  and  upon  that  a  layer  of 
bar-iron,  and  fo  on  alternately,  until  the  trough  is  fuU.  It  is  then  covered  over  with  day^ 
to  keep  out  the  air,  which,  if  admitted,  would  effediually  prevent  the  cementationr  When 
the  fire  is  put  into  the  grate,  the  heat  paflTes  round  by  means  of  flues,  made  at  intervals, 
by  the  fides  of  the  trough.  The  fire  is  continued  until  the  converfioci  is  oomplete, 
which  generally  happens  in  about  eight  or  ten  days.  There  is  a  hole  in  the  fide,  by  vidiich 
the  workmen  draw  out  a  bar,  occafionally,  to  iee  bow  far  the  tranfinutation  has  proceeded. 
This  they  determine  by  the  bliflers  upon  the  fur&ce  of  the  bars.    If  they  be  not  flifficiently 

^  Extracted  from  his  Obfervations  on  Iron  and  Steely  in  the  Manchefter  Memoin,  V.  109.— The  paper  itfelf 
contains  a  concife  and  clear,  though  in  fome  refpects  imperfect,  account  of  the  ufua)  procefles  of  the  fmeltiog 
and  purifying  this  ufcful  metal.  This  author,  who,  ioadverfiendy,  blames  M«  Fourcroy  and  myfclf  for  (his  ine- 
vitable confequence  of  abridgment  ip  our  elementary  writings,  has  himfelf  ikewa  that  the  taik-  of  defcribing 
complex  operations  in  a  few  words,  is  fufliciently  difficult  to  afford  a  claim  upon  the  public  indulgence.— On 
Steel,  fee  Philof.  Journal;  I*  210.  248.  381.  468.  575  j  11*  64.  102. 

changed. 


Gafe9US  Oiiyi  $f  AnHifiuni  to  bi  Rifpirahh.  93 

known;  for  the  fubfequent  operations  may  then  be  properly  condudled,  and  the  inconve- 
'  tiience  attending  the  ufe  of  fome  of  thefe  ialts  may  be  prevented.  This  no  doubt  is  a  lead- 
ing advantage  poffeffed  by  the  man  of  information,  beyond  the  fimple  operative  artift,  who  is 
incapable  of  varying  his  proceflcs  according  to  the  nature  and  Rate  of  the  (alts  he  may  ufe. 
I  fliall  confine  this  paper  to  accounts  of  the  colour  obtained  from  the  oxyde  of  iron : 
1.  When  it  is  ufed  alone  upon  goods  which  have  received  no  previous  preparation,  and,  2. 
when  it  is  employed  jointly  with  the  red  of  madder,  on  a  piece  prepared  to  receive  the  Adri- 
anople  red. 

I.  If  fulphate  of  iron  or  any  other  martial  fait  be  dilTolved  in  water,  and  cotton  be  plunged 
Aerein,  it  will  acquire  a  chamois  tinge,  more  or  lefs  deep,  accordingly  as  the  folution  may  be 
charged  with  the  fait.      The  affinity  of  cotton  with  the  iron  is  fuch,  that  it  attrafts  the 
metal,  and  takes  a  great  part  from  the  acid  which  held  it  in  folution. 

(To  he  concluded  in  our  next*) 


SCIENTIFIC  NEfFSj  Vc. 

Refpirahility  of  the  Gafeous  Oxyd  of  jizote* 

£xtraa  of  a  Letter  from  Mr.  H.  Davy* — Dattd^  Clifton^  April  17,  1799. 

^  X  HAVE  this  day  made  a  difcovery,  which,  if  you  pleafe,  you  may  announce  in  your  Phy- 
sical Journal,  namely,  that  the  nitrous  phofoxyd  or  gafeous  oxyd  of  azote,  is  refpirable 
when  perfe£^ly  freed  from  nitric  phofoxyd  (nitrous  gas).  It  appears  t^  fupport  life  longer  than 
common  air,  and  produces  effe&s  which  I  have  no  time  to  detail  at  prefent.  Dr.  Mitchill's 
dieory  of  contagion  is  of  courfe  completely  overturned ;  the  miftake  of  Prieftley  and  the  Dutch 
chemifts,  probably  arofe  from  their  having  never  obtained  it  pure.  I  am  now  preparing  a 
faper  on  this  fubje£l,  for  the  next  volume  of  the  Weft*country  Contributions." 

In  a  fubfequent  communication,  Mr.  Davy  exprefles  his  apprehenfion,  left  a  general  notice 
cf  the  refpirahility  of  gafeous  oxyd  of  azote  fhould  induce  anyone  to  make  injurious  ex- 
periments on  himfelf,  and  therefore  wilhes  it  ihould  be  added,  that  the  circumftances  of  (afety 
and  of  hazard  will  be  fpeedily  pointed  out  to  the  public.  A  train  of  experiments,  by  which  he 
hopes  to  clear  up  this  perplexed  fubjccl,  are  in  progrefs ;  and  he  is  the  more  iblicitous  that  this 
general  notice  (hould  be  publiihed,  becaufe  fome  moft  remarkable  phenomena  witnefled  by 
divers  perfons,  in  the  pneumatic  inftitution,  and  leading  to  ufeful  pra£liceS)  have  been  a  good 
dad  talked  of  at  Briftd>  and  an  erroneous  anticipation  may  get  into  print>  before  the  true 
account  can  be  prepared. 

I  under* 


>..  -  k  -----  ■ 


r 


I 

I 

f 
^ 


-5+ 


Sdenlijic  Nitu/t. 


1  underfiand  by  a  letter  from  the  Rev.  Mr.  Pnrfon,  of  Lincoln,  thtt  he  did  not  mean  ttr 
imply,  by  the  words  in  the  firft  parcnthefis  on  pags  53,  that  the  earth  has  any  [lerceptible  irre- 
gulaiitics  in  its  rotation,  of  which  he  obfcrvcs  that  a  rufpicion  was  entertiuned  by  Kepler.  The 
inaccuracy  of  exprellion  arofc  from  bis  attention  being  dirc^ed  to  the  length  of  the  apparent 
fohr  day,  inftead  of  mean  folar  time.  ■ 


Mtf  Produce  cf  European  Sugar. 
I  have  heard  much,  within  the  laft  fortnight,  concerning  the  produfl  of  fugar  from  1 
fpecles  of  (he  beet,  or  mangel  wuriel,  by  Mr.  Achari).  The  experiments  of  Margraaf 
and  others  many  years  ago,  who  obtained  fugar  from  vegetables  by  treatment  with  alcohol, 
are  well  known  to  chemil^s.  But  it  is  ftated,  that  the  chemlfl  of  Berlin,  has  obtained  it 
by  a  proccfi  fufEciently  cheap,  and  in  quantities  fo  confiderabie,  that  if  the  reports  which  are 
circulated  be  true,  the  difcovery  will  bid  fair  to  change  a  large  part  of  the  commercial  fyftem 
jif  the  world,  with  regard  to  this  great  article  of  modern  confumptioiu  The  experiments 
are  faid  to  have  been  confirmed,  on  a  large  fcale,  by  Klaproth.  But  I  muft  defer  any 
further  report,  until  the  fubje£tcan  he  exhibited  in  an  unqueftionable  fhape. 


A  tranflation  of  Dr.  Gren's  Elementary  Treatifc  on  Chemiftr)-,  in  two  volumes  oflavo, 
is  ready  for  the  prefs.  This  work  is  an  abridgement  by  the  author,  of  his  own  fyftem  of 
chemiftry,  of  which  the  fecond  edition,  in  four  large  oflavo  volumes,  was  publifhed  in  1796* 
A  work  highly  efleemcd  diroughout  Germany,  for  fyftematicil  arrangement,  and  the  extent 
of  knowledge  it  difplays.  Though  Dr.  Grcn  was  neither  of  the  phlogiftian  nor  antiphlo- 
giflian  order  of  chemifts,  but  maintained  a  fyflem  of  his  own,  in  which  bot!i  theories  were 
combined,  "he  has  neverthelcfs  chofen  to  follow  the  antiphlogiflian  fyftem  in  his  abridged 
work.     The  tianflacor  has  added  the  difcoveries  made  fince  the  year  1796. 

Dr.  Trederick  Albert  Charles  Gren,  public  profeflbr  of  medicine  at  Halle,  died  on  the  26th 
of  November  laft,  of  a  nervous  fever,  in  the  38th  year  of  his  age.  The  public  proofs 
which  he  gave  of  ability  and  induflry,  have  rendered  his  lofs  a  fevere  affliflion  to  the  fciendfic 
world.  He  was  author  Of  an  Introduflion  to  nacuiai  philofophy,  of  which  the  third  edition 
was  publithed  in  1797  i — Elements  of  Pharmacology,  in  two  rolumes  o<Savo,  of  which  the 
Hecond  edition  was  publifhed  in  1798  ;— and  alfo  the  Journal  of  Natural  Philofophy,  began  in 
^1 770,  of  which  eleven  volumes  are  extant. 


4 


April  J7, 

]  have  received  fome  papers  from  Dr.  Beddoes,  relating  to  the  fubjefl  animadvcrttd 
upon  at  page  41  of  the  prefcnt  volume,  and  alfo  a  letter  from  Dr.  Gibbes.  Dr.  Beddoes  doe* 
not  confider  his  documents  as  fuScicntly  intcrcfling  to  the  public,  ta  dcfervc  a  place  in  the 

Journal ; 


4 


DifcufftoH  nlatittg  U  the  Str^Hfian  rfSddburj*  9j^ 

^    Journal ;  but  wiflies  them  to  be  printed  on  a  feparate  leaf.    But  as  fuch  a  leaf  would^no 
doubt)  be  confidered  and  preferved  by  all  my  readers  as  a  part  of  the  Journal,  and  as  the 
general  caufe  of  morality  and  fdence  is  involved  in  difcuffions  of  this  nature,  I  have  prefeired- 
diat  an  abridged  ftatement  fhould  appear  in  the  Journal  itlelf. 

The  papers  I  have  received  are:,  i.  Letter  from  Dr..BeddoeS)  dated  Aprir24.     2.  Letter 
from  the  Rev.  Mr.  Richardfon,  of  Bath,  to  Dr.  Beddoes,  dated  17  (I  fuppofe  April).     3. 
Queftions  to  Mr.  Notcutt,  by  Dr.  Beddoes..   4.  Mr.  Notcutt's  anfwer,  dated  April  21. 
5.  Queries  to  Mr.  Davy,  with  his  replies.     Thefe  papers  were  received  yefterday,  and  by. 
this  morning's  poft  I  received  a  letter  from  Pr.  Gibbes,  dated  April  26.     In  Mr.  Richardfon's 
letter  it  is  ftated  to  be  a  mifreprefentation,  that  Mr.  Notcutt  pointed  out  fome  fulphate  of 
firondan  in  his  (Mr.  R's)  coUeftion ;  but  he  admits,  that  Mr.  N.  faid  the  fpecimen  in  queftion 
might  probably  be  fulphate  of  ftrontian;  but  Mr.   Richardfon  does  not  remember  ever 
mentioning  this  conjefture  to  Dr.  Gibbes. — Mr.  Notcutt  in  his  letter  admits,  that  Dr.- 
Beddoes'  ftatement  of  Mr.  N.  having  recognized  the  fulphate  of  ftrontian,  is  contSt  to  the 
befl  of  his  recolledion ;  that  in  a  late  conference  with  Mr.  Richardfon,  this  laft  gentleman  had '. 
affirmed,  that  Mr.  Notcutt  had  notfpoken  with  certainty  in  giving  his  opinion  of  the  fpecinien  at 
the  time  alluded  to :  upon  which  Mr.  Notcutt  obferves,  that  he  cannot  pretend  to  repeat  exadly 
the  words  he  may  have  ufed,  but  that  it  is  evinced,  that  he  felt  the  ftrongeft  convidion  of 
its  being  that  fubftance,  by  his  informing  Dr.  Beddoes,  Mr.  Clay  field,  and  others,  immediately 
Upon  his  return  to  Briftol,  that  it  had  been  found  near  Sodbury,  as  well  as  by  his  authorizing 
Ae  former   to  notice  it  in  the  volume  of  papers  juft  publifhed;    that   he,  Mr.  Notcutt. 
(from  Dr.  Gibbes*  knowledge,  that  conftderable  quantities  of  the  fame  fubftances  had1»eenj 
dilcovered  near  Briftol  by  Mr.  Clayfield,  and  that  Mr.  Clayfield  had  long  beenengaged  in  a. 
courfe  of  experiments  upon  its  analyfis,  and  that  no  official  account  of  it  was  before  the  public), 
cannot  account  for  His  omitting  to  notice  what  was  fo  inunediately  conne£ted  with  the 
fubjeS  of  his  paper, .  without  fuppofmg  that,  he  wiftved  to  take  to  himfelf  more  than  the 
merit  of  having  analysed  the  fpecimen  from  Sodbury. — Mr.  Davy  in  his  anfwers  to  the  queries 
propofed  to  him,  ftates,  that  Mr.  Notcutt,  in  a  converfation  previous  to  the. publication  of 
Dr.  Gibbes'  experiment  in  the  Philofopbical  Journal,  did  inform  him  that  fulphate  of  ftrontian 
was  found  in  large  quantities  near.  Sodbury;  and  admits,  that  Mr.  Notcutt  had  mentioned 
before  that  period^  that  he  (Mr.  Notcutt)  had  pofitively  told  Mr.  Richardfon,  that  the 
mineral  in  queftion  was  fulphate  of  ftrotian.    And  laftly,  he  partly  admits  and  partly  ftates, , 
that  Dr.  Gibbes  was  pjefent  at  converiations  refpe£^ing  Mr.  Clayfield's  analyfis*  who  con^ 
fidentially.  communicated  to  him  (fads  or  incidents]  refpefUng  the  fame  mineral  in  the  fame 
diftri£l..  And  that  Dr.  Gibbes  muft  have  known,  that  by  publiftiing  his  analyfis  prior  to  Mr. 
Claj(ield*8,  and  without  communicating  it  to  him,  he  (Dr.  G.)  would  be  confidered  as  the 
fiirfl:  difcoverer  of  thfe  fulphate  of  ftrontian,  to  the  prejudice  of  Mr.  Clayfield,  whofe  name 
ought  to  have  been  mentioned.— The  teftimony  of  Mr.  Clayfield  himfelf  could  not  be  obtained  ' 
in  time  for  Dr.  Bieddocs  to  fend  it  with  the .  other  papers,  becaufc  Mr.  C.  was  then  abfent 
from  BriftoL 

Olta 


90  On  the  Antifuiff  df  tHi  Aresmetif* 

This  notice  i4  not  accurate^  if  the  poem  De  Ponderibs  et  Menfuris^  printed  at  die  end  of 
the  ^jrorks  of  Prifcian,  and  admitted  by  all  the  learned  to  have  been  written  by  Rhcmnins 
Fannius  Palaemon  be  truly  afcribed  to  that  grammarian:  Rhemnius  lived  under  Tiberiu8» 
Caligula,  and  Claudius  Csefar,  and>  confequently,  was  three  centuries  anterior  to  Hypacia. 
The  follow  ing  is  the  defcription  which  he  gives  of  Areometry^  which  is  equally  valuable 
^for  its  per  fpicuity  and  exa£lnefs: 

Ducitur  argento  tenuive  e<  xre  cylindruS) 
Quantum  inter  nodos  fragilis  produci^  arundo^ 
Cui  cono  interius  modico  pars  ima  gravatur 
Ne  totus  fedeat,  totufve  fupematet  undi8>  ' 
Lineaque  \  fummo  tenuis  defcendit  ad  ima, 
Du£la  fuperficie,  tot  quseque  in  frufta  fecatur 
Quot  fcruplis  gravis  eft  argenti  xrifve  cytindrus*- 
HoC|  cujufque  potes  pondus  fpefbure  liquoris. 
Nam  fi  tenuis  erit,  majori  immeigitur  unda ; 
Sin  gravior,  plures  modulos  fuperefle  notabis. 
Aut  fi  tantimidem  laticis  fumatur  utrinque 
Pondere  praeftabit  gravior  5  fi  pondera  fecum 
Conveniunt,  tunc  major  erit  quae  tenuior  unda  eft> 
Quod  fi  ter  feptem  numeros  texifle  cylindri^ 
Hos  videas  latices,  iUos  cepiile  ter  oQtOy 
His  drachml  gravius  fatearis  pondus  inefle. 
Sed  refert  xqui  tantum  conferre  liquoris, 
Ut  gravior  fuperet  drachm^,  quantum  expulit  undae 
Ulius  aut  hujus,  teretis  parfima  cylindri*. 

It  cannot,  therefore,  be  doubted  but  die  Areometer  was  an  inftrument  well  Kriown,  and 
commonly  ufed,  three  hundred  years  before  the  birth  of  Hypacia.  It  is  difficult  to  conceive 
how  Synefius,  contemporary  and  friend  of  this  celebrated  lady,  could  attribute  the  invention 

*  In  Engliili,  <<  A  cylinder  is  aade  of  iihrer,  or  thin  brafs,  in  length  equal  to  the  diftance  between  the  knots  of 
a  brittle  reed.  The  lower  partis  loaded  within,  fo  that  it  (bail  neither  totally  fink,  nor  entirely  flbat.  A- fine 
line  is  drawn  from  the  upper  to  the  lower  extremity  of  its  furfacc,  and' divided  into  as  many  portions  as  the 
fcruples  which  ezpref*  the  weight  of  the  cylinder.  With  this  inftrument  the  relative  weight  of  any  fluid  may 
be  afceruined :  for,  if  it  be  Ught,  the  cylinder  will  fink  deeper  ^  or»  if  heavy,  the  number  of  diviiions  above  the 
furface  will  be  more  confiderable.  If  equal  bulks  of  different  fluids  be  taken,  the  denfeft  will  exceed  the 
other  in  weight ;  or,  if  the  weights  be  equal,  the  rareft  fluid  will  occupy  the  greater  fpace.  For  example,  if 
the  cylinder  be  found  to  fink  through  twenty-one  divifions  in  one  fluid,  and  in  another  through  rwenty-four» 
it  may  be  concluded,  that  the  heavier  exceeds  the  other  by  three  fcruples,  or  one  drachm.  But,  it  is  more  ac- 
curate, inftead  of  attending  to  the  difference,  to  compare  the  two  fluids,  by  attending  to  the  quiotitici  of  each 
in  magnitude^  which  are  difplaced  by  the  immerfed  part  of  the  cyliad^r.** 


JnciifH  Ohfirviithni  %n  SpidJU  Gravity*  91 

to  her  "*•    But  the  follo^raig  line  immediately  after  this  defcription  b  RhemnluSj  is  ftiU 


more  remarkable : 


Nunc  aliud  partum  ingenio  trademus  eodem. 


*<  Let  us  now  defcribe  another  invention  of  the  fame  genius.' ~After  which  he  proceeds 
to  defcribe  the  method  ufed  by  Archimedes,  to  afcertain  the  quantity  of  filver  contamed  in 
the  crown  of  Hiero. 

It  appears,  therefore,  to  be  certain,  that  we  owe  the  invention  of  the  Areometer  to  the  fame 
man  who  enriched  the  accurate  fciences  with  fo  many  difcoveries,  and  who,  to  the  glory 
of  his  talents,  added,  that  of  living  for  the  welfare  of  his  country,  and  dying  in  its  de« 
fence.' 

The  poem  of  Rhemnius,  or,  rather,  the  fragment  which  remains,  deferves  to  be  known. 
Independent  of  the  two  defcriptions  I  have  quoted,  and  a  complete  fyftem  of  ancient  mea« 
fures,  it  contains  other  interefting  details.  Such  is  the  following  obfervation,  which  fuppofes 
experiments  of  fome  delicacy  on  the  fpecific  gravity  of  liquids. 

f  Namque  nee  errantes  undis  labentibus  amnes 
Nee  merC  puteis  latices,  nee  fonte  perenni 
Manantes,  par  pondus  habent :  nee  denique  viiia, 
Qiue  campi  aut  coUes,  nuperve  aut  ante  tulere. 

Permit  me  to  obferve  the  elegance  and  accuracy  of  thefe  cxpreflions.  They  appear  to  me 
to  belong  to  a  writer  of  good  latinity :  and  to  obviate  all  the  doubts  which  can  be  raifed  con- 
cerning the  date  of  the  poem,  another  citation  will  confirm  this  idea : 


-Pondus  rebus  natura  locavit 


Corporeis :  elementa  fuum  regit  oihnia  pondus. 
Pondere  terra  mapet ;  vacuus  quoque  ponderis  iEtlicr 
Inde  fefla  rapit  volventis  fydera  mundi. 

An  author  of  die  fizth  century,  fuch  as  Prifcian,  the  only  one  to  whom  the  poem  of 
Rhemnius  could  be  attributed,  could  not  eafily  have  compofed  thefe  verfes. 

*  With  aM  the  advantages  of  the  art  of  prinUAg,  we  fiod,  that  valuable  inventiont  arc  forgecten,  and  re  .in- 
vented, during  the  lapfe  of  |>eriods  much  ihoner  than  three  centuries.  Whoever  will  pcfufe  the  writings  of 
Boyle,  Kunkel,  Hooke,  Wren,  and  the  regiilers  of  the  learned  focieties  and  fcientific  correfpondences  during 
the  laft  century,  will  have  ample  reafoniobe  convinced  of  tliis.— Hypacia  might  be  the  fecond  inventor. — N. 

')' Jn  Englifli,  *'  The  weights  of  river,  well,  and  (pring- water,  are  different;  as  are  likewifc  the  vfises,  ac* 
'*  cording  to  the  place  of  their  growth,  in  liilis  or  places,  and  the  time  of  keeping.*' 

N  a  Chemical 


gz  On  tbi  Ufi  rf  Irm  in  Djlng^ 

XII. 

Chemical  Conjidirattons  en  thi  Ufe  of  the  Oxydes  of  Iron  in  the  Dying  ef  Cettm. 

By  y.  A.  Chaptal  *. 


T 


H  E  oxyde  of  iron  has  fo  ftrong  an  attradlion  to  the  fibre  of  cotton,  that  if  the  latter  be 
plunged  in  a  iaturated  folution  of  iron  in  any  acid  whatever,  it  afllimes  a  chamois  ycUovir 
cdiour,  ef  greater  or  lefs  intcniity,  according  to  the  ftrength  of  the  folution.  It  is  no  le& 
curious  than  eafy  to  make  the  experiment  of  paffing  a  piece  of  cotton  through  a  Iblution  of 
.fulphatc  of  iron  rendered  turbid  by  theoxyde  which  remains  fufpended  in  die  ftuid.  Nothing 
more  is  neceflary  than  to  pafs  the  cotton  dirough  the  hath^  from  which  it  leizes  the  lafl: 
particle  of  the  oxyde,  and  rellores  its  tranfparancy*  The  folution)  which  before  was  yellowi(hp 
immediately  becomes  more  or  lefs  green,  according  to  its  ftrength. 

The  colour  which  the  oxyde  of  iron  givc»  to  cotton^  becomes  deeper  bj  iimple  expofure 
to  the  air ;  and  this  colour,  which  is  foft  and  agreeaUe  at  firft  taking  out  of  the  bath,  becomes 
hard  and  ochrcous  by  the  progref&ve  oxydadon  of  the  metiL 

The  colour  of  the  oxyde  of  iron  is  very  Iblid.  It  refiftft  the  aftioa  not  oolj  of  the  air  and 
water,  but  likewife  of  alkaline  folutioiis.  Soap  gives  it  brightneis .  without  perceptibly 
diminifhing  its  intenfity. 

From  thcfe  properties  it  is,  that  the  art  of  dying  has  availed  it(elf  of  the  oxyde  of  iron  as  a 
moft  valuable  colouring  principle.  But  I  have  fucceeded  in  giving  a  new  extenfion  to 
the  applications  of  this  oxyde.  I  ihall  confine  myfelf  in  prelenting  to  the  Inftitute  thofe  refults 
only  which  deferve  to  be  adopted  in  the  prafkice  of  manufiLdurers,  and  have  been  executed  for 
feveral  years  in  my  dying-works. 

In  order  that  the  oxyde  of  iron  may  be  conveniendy  ^ipplied  to  the  cotton  thread,  its  ibiudoa 
muft  firft  be  eifefled.    Acids  are  ufed  z&  the  beft  (blvents. 

Moft  dyers  make  a  myftery  of  the  acid  they  ufe  ;  but  the  univerlal  pra&ice  is  confined  to 
the  acetous,  the  fulphuric,  the  nitric,  and  the  muriadc  adds. 

Some  dyers  attribute  great  differences  to  the  acid  they  ufe  in  the  folutipn  of  iron;  but  the 
preference  is  commonly  given  to  the  acetous  acid. 

This  predileAion  appears  to  me  to  be  grounded  much  lefs  upon  die  difference  of  the 
colours,  which  one  acid  or  the  other  may  give,  than  upon  the  corrofive  aAion  which  each  of 
them  exerts  to  different  degrees  on  the  ftuff.  This  is  (b  great>  with  relpe«3  to  the  fulphate 
and  the  muriate,  that  if  the  piece  be  not  waihed  immediately  as  it  conies  out  of  the  bath,  it 
will  certainly  undergo  an  effed  of  the  fame  nature  as  combuftion;  whereas  die  iblutions  in 
the  acetous,  %t  any  other  vegetable  acid,  do  not  produce  this  inconvenience. 

The  iron  appears  to  exift  at  the  fame  degree  of  oxydaiion  f  in  the  different  acids,  fince  it 
produces  the  fame  fhade  of  colour  when  precipitated ;  and  any  acid  iait  may  be  indifcrimi« 
jutely  ufed,  provided  the  nature  of  the  fait,  and  the  degree  of  faturation  in  the  acid^  be  fufficiendy 

•  Read  to  the  French  Narional  Inftitute,  s  i  Germinal,  in  the  fixth  Republican  year,  and  inferted  in 
the  Annalet  de  Chimle,  XXVI.  a66,  whence  this  tranflation  it  made. 
f  Oa  this  fubjcft  fee,  however,  the  Philof.  Joumsl^  I.  453. 

luiown; 


Hiltf  Ji'ianal  MjaJUrAiufif-vif, 


•'/ff^f^//  ■^/fmfr  f'//Arr'j^fitfr/ff  /n 


fnrfi'urf>/tfi 


_  :?3///'.  /rr^f  rn/r .  /iv/ 


ggMBWBEaaaaefcggBB^ii^'Mi.iii  iBBeggggggg i    ■nigcggae 


JOURNAL 


OF 


NATURAL   PHILOSOPHY,   CHEMISTRY, 


AND 


THE   ARTS. 


JUNE  1799. 


ARTICLE    I. 

I 

'An  Account  of  firm  Endeavours  to  afcertain  a  Standard  of  ff^etght  and  Meafure.    By  Sir' 

George  Shuckburgh  Eveltn^  Bart.  F.R.S.  and  A.S.* 


H 


AVING  for  fomc  years  turned  my  thoughts  to  the  confideration  of  an  invariable  and 
imperifhable  ftandard  of  weight  and  meafure,  as  being  a  thing  in  a  philofophical  view  highly 
defirable,  and  likely  to  become  extremely  beneficial  tu  the  public,  I  had,  fo  early  as  the  year 
1780,  taken  up  the  idea  of  an  univerfal  meafure,  from  whence  all  the  reft  might  be  derived, 
by  means  of  a  pendulum  with  a  moveable  centre  of  fufpenfion,  capable  of  fuch  adjuftments  as 
to  be  made  to  vibrate  any  number  of  times  in  a  given  interval;  and  by  comparifon  of  the 
difference  of  the  vibrations,  with  the  difference  of  the  lengths  of  the  pendulum  (which  difference 
alone  might  be  the  ftandard  meafure),  to  determine  its  pofidve  length,  if  that  fliould  be 
thought  preferable,  under  any  given  circumftances ;  by  which  means  all  the  difficulties  arifing 
in  determining  the  adual  centre  of  motion  and  of  oicillation,  which  have  hitherto  fo  much 
cmbarrafled  thefe  experiments,  would  be  gotten  over.  • 

§•  2.  I  made  (everal  computations  of  the  probable  accuracy  that  might  be  expeded  from 
Tuch  an  experiment,  and  was  fatisfied  with  their  refult.    But  not  feeing  clearly  bow  fuch  a 

*  Philof.  Tranf.  1798. 

Vol.-  III.— JuNB  1799,  O  pendulum 


98  "O^  a  fianiard  Mtajurt  fr^m  a  Pendulum. 

pcQil^Iuiii  could  b«  cooiMiA^d  loapkceofmecbiQUintDnttmbertbevtbrsdoitt  widio^ 
ing  tnem,  I  dropped  the  idea  for  that  time,  I  learnt,  however,  fome  time  afterwards,  diat  Mr. 
John  Whitehurft,  a  very  ingenious  perfon,  had  been  in  purfuit  of  the  fame  objeA,  with  better 
fuccefS)  and  had  contrived  a  machine  fully  correfponding  to  his  expe&ations  and  my  wi(hes» 
This  he  afterwards  explained  to  the  world  in  a  pamphlet  entitled  ^  An  Attempt  to  obuin 
**  Meafures  of  Length,  &c.  from  die  Menfuration  cif  TimC)  or  the  true  Length  of  Pendulums,'' 
publiihed  in  .1787.  Mr.  Whitehurft  having  therein  done  all  that  related  to  the  ftandard 
meafure  of  length,  and  fuggefted  that  of  weighti  it  appeared  to  me  that  it  remained  only  to 
verify  and  complete  his  experiments. 

§•  3.  For  this  purpoTe,  by  the  kind  affiftance  of  my  firiend  Dr.  G»  Fordyce,  Who  at  Mr* 
Whitehurft's  death  had  purchafed  his  apparatus,  I  wa$  fiimiflied  witft  the  very  itucfaine  witb 
which  Mr.  Whitehurft  had  made  his  obfervations*     I  alfo  procured  to  be  made  by  Mr. 
Troughton  a  very  excellent  beam-compa&  or  divided  (cale,  furniflied  widi  microfcopes  and 
micrometer,  for  the  moft  exad  obfervations  of  longitudinal  meafure  \  as  aUb  a  very  nice  beam 
or  bydroftatic  balance,  fenfible  with  the  to«  of  a  grain  when  loaded  witb  61b»  troy  at  each  end. 
Mr.  Arnold  made  me  one  of  his  admirable  time-Jceepers,  in  order  to  carry  time  firom  my  fidereal 
.  legubtor  in  my  obfervatory,  with  which  it  was  acljufted,  to  the  room  wherein  I  had  fixed  Mr. 
Whitehurft's  pendulum ;  and  who  having  taken  a  journey  into  War^irickfliire,  was  fo  good 
as  to  affift  in  the  beginning  of  thefe  experiixients.^    Thus  equipped,  I  went  to  work  in  tiie 
latter  end  of  Auguft,  1796,  when  the  temperature  was  about  60^,  firft  to  examine  the  length 
of  the  pendulum ;  when,  to  my  great  mortificattoo^  I  found  that  the  thin  wire  of  which  die 
rod  confifted  was  too  weak  to  fupport  the  ball  in  a  ftate  of  vibration ;  and  that  after  15  or  20 
hours'  aAion  it  repeatedly  broke.    The  £une  misfortune  attended  taf  trialt  wilk  tbrae  odier 
different  forts  of  wires  that  I  had  obtained  from  London.    Whether  this  accident  happened 
from  any  rufl  in  the  old  wire,  or  from  want  of  due  temper  in  die  new,  or  from  its  being  tod 
liiudi  pinched  between  die  cheeks  ^^  I  catinot  tdl.    I  can  only  obfertev  that  all  die  wires 
that  I  ufed  were  coniiderably  heavier,  and»  diefeforC)  ptobaUy  (trooger  than  what  Mr.  White* 
hurfl  mentions,  viz.  3  grains  in  weight  for  80  inches  in  length ;  nay,  mine  proceeded  a» 
fiv  as  from  5  to  6  grains  for  diat  length,  and  ytt  1  eould  never  get  it  to  fupport  dke  ball 
during  die  whole  period  of  my  experiment*    This  being  the  eafe>  tod  being  in  die  oimitiyf 
br  removed  firom  die  manufiiAory  of  diie^iine  Wire,  I  was  rdodAndy  compeHed  to  reKkiipiiflik 
dds  part  of  the  operation  to  fome  more  fovoursMe  opportunit]^   In  die  mean  vAiSin^  bowever,^ 
I  diought  it  defirable  to  meafiirr the  difierence  of  die  lengdis  of  Mr.  Whitehorft's  pendulum 
from  his  own  obfervadons  \  for  very  fortunately  die  marks  dut  he  had  made  on  die  brafo 
vertical  ruler  of  his  machine  were  Aill  vifible,  and  diis  interval^  whidi  he  caUs  ^  59, 892 
inches,"  I  determined  on  my  divided  fcale  made  by  TroughMi  from  Mr.  Bindrs  ftandard  10 
bes=  59,99^58  inches,  from  a  mean  of  four  difierent  trialt  in  the  temperatmo  uf  64^ ;  dut 
mean  dUEbriftg  from  die  extremes  only  ss,ooo3  indi  f. 

^  c  c  Fig.  I.  of  Piatt  IT.  ia  Blr.  Whkebnrft't  pamphlet. 

t  Sec  the  remark  in  PhUof.  Journal,  III.  32*  aoce«««N«  ^        ^ 


§.4.  By  diis  exttnination,  if  I  have  not  verified  I  have  at  leaft  preferved  Mr.  Whitdiorft^a 
fiandard ;  and,  for  the  prefent,  I  (hall  confider  this  meafure  of  the  difference  of  the  lengdi  of 
the  two  pendulums,  vibradng  4a  and  84  times  in  a  minute  of  mean  time}  as  corre&  On  this 
prefumption  I  Ihall  proceed  to  the  examination  of  weight. 

§.  5*  From  the  opinion  of  different  (kilful  perfons  with  whom  I  have  conferred,  as  well  as 
from  the  refult  of  my  own  confiderations,  I  am  inclined  to  believe,  there  is  Hfcrdly  any  body 
in  nature  with  vrfiich  we  are  iamiKaily  acquainted,  that  is  of  (b  (imple  and  homogenous  a 
quality  as  pure  diftiBed  water,  or  fo  fit  for  the  purpofesof  this  enquiry ;  and  I  have  concluded, 
that  if  the  weight  of  any  quantity  of  water  whofe  bulk  had  been  previoufly  meafured  by  the 
'  dbevementioned  fcale,  could  be  attained  under  a  known  preffure  *  and  temperature  of  the 
atmnfphcrc^  we  0iould  be  in  poffeffion  of  a  general  ftandard  of  weight 

5*  6.  With  this  view,  I  diredled  Mr.  Troughton  to  make,  in  addition  to  die  very  fenfiUe 
hydroftadc  balance  before  mentioned,  a  iolid  cube  of  bra^^  whofe  fides  were  5  inches  \  and  alfo 
a  cylinder  of  the  (ame  metal,  4  inches  in  diameter  and  6  high.  From  St.  Thomas's  hofpital, 
liy  £rvoiir  of  Dr.  Fordyce,  I  procured  3  gallons  pf  diftilled  water  ^  with  thefe  I  made  die 
Ibilowing  obfervations  :  but  before  I  relate  the  experiments,  I  will  defcribe  the  apparatus. 

Mr.  Wkitehurft's  machine  for  meafuring  the  pendulum,  has  been  fufficieiftly  explained  iai 
Ms  pamphlet  mendoiied  above ;  my  divided  fcale,  which  was  a  new  inftrumenti  was  as  follows; 

§•  7*  Df/mfiim  of  the  Biam^ompgfs^  or  Divided^caU  $f4qugl  parts. 

a  h  (Plate  V«  fig.  i.}  is  a  block  or  beam  of  mahogany,  6  feet  3  incites  long,  6  inches 
deep,  and  5  wide,  upon  which  are  laid  two  bra(s  rules,  c  d  e  2ivi/g^  each  divided  into  60 
inches  and  tenths.  The  former  of  thefe,  called  the  fcale,  is  for  a  time  kept  immoveable 
by  the  finger-fcrews  c^  dy  and  is  fumifhed  with  fine  hair4iae  divifions,  intended  to  be  viewed 
<mly  by  the  microfcopes,  hi:  die  latter,  called  die  beam,  has  no  modon  but  by  means  of  the 
ftxew  f,  and  bears  ftrongcf  diriikms  upon  it,  widi  which  the  Aiding  pieces  or  indexes  at  i 
and  as  may  readily  be  compared  by  the  naked  eye,  and  is  intended  only  to  fet  the  jmiorofoopes, 
er  sather  die  wires  in  dieir  fopus,  so  the  required  diftance  nearly,  viz.  to  widiin  t4«  or  1  ov 
«f  aninch.  The  microfcopes  arc  compound,  and  fimilar  to  thofe  defcrifoed  by  the  late  General 
]loy  in  his  aocoimt  of  his  krge  dieodolite.  (See  PhiL  Tranf«  voL  LXXX.)  The  one 
at  ^  contains  onlycro(s-mrcs  fix»d  in  its  focus;  the  other  at  i  has  a  micrometer  alfo,  by  means 
«f  which  its  crofe- wires  may  be  moved  to  die  right  or  Id^  or  over  the  image  of  thedivifiont 
of  the  fcale,  any  givm  <pa£e  not  exceeding  ^  indi;  and  the  quantity  fo  aoirtd^may  bo 
meafiwedby  the  divifions  on  the  :fcrew*head  paffing  under  die  index  at  «.  The  divifions  on 
diefe  ndes  have  been  caUed  indies  and  tenths ;  it  was  not  necedary  that  they  fhould  be  more 
than  -equal  parts  ;  but  they  were  la  fs£t  laid  down  by  Mr.  Troughton  from  a  fcale  of  the 
late  excdlent  ardft  Mr.  J.  Bird,  who  iiad  divided  into  inches  feveral  fcales  of  different  lengths  ; 
one  of  which,  42  inches  long,  bdonged  tt>  the  late  General  Roy;  a  (econd,  of  5  feet,  was 

*  I  do  not  here  mean  to  infer  any  opinioa  refpe£ling  the  compreflibility  of  water,  but  only  to  fay,  that 
vfhere  water  or  any  thing  dfe  is  weighed  in  air,  the  deniity  of  that  medium,  ai  ibewn  by  the  barometer  and 
theniomecer,  rnuft  be  known  in  order  to  auks  allowances  for  it  if  ncceflary. 

O  2  j>urchafcd 


^00  DifcrlptidH  a$ti  Ufg  rf  0  Bidm^mipafs 

purchafed  by  Alexander  Aubert,  efq; }  and  a  third,  of  90  inches,  which  it  now  the  ptoptrtf  of 
the  Royal  Society,  is  kept  in  their  archives,  and  is  faid  to  have  been  iifed  by  Mr.  Bird,  in 
dividing  his  large  mural  quandrants  *.     Bciides  thefe,  he  made  two  ftandards  of.  thi^e  feet^ 
by  order  of  the  Houfe  of  Commons,  of  which  I  (ball  fpeak  more  hereafter.    The  mode  of  ufing 
this  inftrument  is  as  follows; 

§.  8*  Let  the  obje£fc  to  be  meafured  be  fuppofed  to  be  about  fix  incbes*  and  let  it  be 
defired  to  compare  it  with  the  interval  between  the  2odi  and  the  26th  divifions  in:  the 
fcale  c  d :  move  by  hand  the  microfcope  hj  with  its  Aiding  plate,  until  the  divifion  of  the 
index  at  i  coincide  widi  the  divifion  of  20  inches  on  the  rule  of  f  g\  then  move  by  hand 
alfo  the  microfcope  1,  with  its  Aiding  plate,  and  appendage/  m  n  0,  unfil  the  index  divifion 
near  m  coincides  with  26  on  fg :  the  axes  of  the  microfcopes,  or  centres  of  their  croft-wires, 
will  be  at  the  approximate  diftance  of  6  inches.  To  corred  this,  examine  if  the  wires  of  ^ 
correfpond  with  a  divifion  on  c  di  if  not,  move  the  rulofg  backward  or  fbrwarf  by  the 
fcrcw  g  till  they  do ;  then  will  the  microfcope  b  be  adjufted.  Now  examine  if  the  wires  in  i 
cover  exiaftly  a  divifion ;  if  they  do  fo,  the  true  interval  of  6  inches  between  the  microfcopes 
is  obtained  ;  if  not,  move  the  microfcope  1  a  little  by  means  of  the  fcre^  till  they  do,  and 
both  the  microfcopes  will  be  adjufted :  then  remove  the  rule  c  e  dAxom  its  place,  by  taking  out 
the  fcrews  c  e  d^  and  place  the  objeA  to  be  meafured  in  its  room,  at  the  fame  time  taking 
care  that  it  be  exa&ly  in  the  focus  of  the  obje^-glafs  of  the  microfcope,  in  fuch  a  manner  that 
one  extremity  may  correfpond  with  the  wires  in  the  microfcope  b  \  that  done,  if  the  other 
extremity  coincide  with  the  wires  in  /,  the  dimenfion  of  the  objed  is  exa£lly  i  inches ;  if  not* 
reftore  the  coincidence  by  turning  the  micrometer  fcrew  n,  and  the  divifions  at  0  will 
give  the  difference  in  loooths  and  lopooths  of  an  inch  -f-  or  —  6  inches. 

§•  9*  DifcriptUn  of  the  Hydrojtatic  Balance. 

abed  (Fl.  V.  fig.  4. )  is  a  box,  which  contains  the  whole  apparatus  when  not  in  ufe ;  and  when 
iifed,  (erves  as  a  foot  to  the  hollow  brafs  pillar  efg  i6,  which  is  fixed  into  it  by  the  four  fcrews 
at  the  bottom  e  and/.  This  pillar  contains  another  within  it,  and  which  is  raifed  up  and 
down  about  r\j  inch,  by  means  of  the  fcrew  a*  :  »  0  is  the  beam,  27  inches  long,  and  3,9  inches 
wide  .in  its  greateft  diameter ;  each  arm  of  which  is  made  hollow  and  conical,  for  ftrength  and 
lightnefs  ;  through  the  centre  at  m,  pafies  the  axis  of  motion,  the  ends  of  which,  when  ufed,  aoe 
fuffercd  to  fall  gently  upon  two  cryftal  pkmes,  which  are  fet  horizcmtally,  by  means  of  the 
fpirit  levels  k  4  and  the  fcrews  underneath  the  box,  at  c  and  b.  The  ends  of  this  ^xis  are  bf 
hardened  (leel,  of  a  wedge-like  Aiape,  and  reduced  to  a  fine  edge,  vis*  to  an  angle  of  about  40% 
fo  as  to  move  upon  the  planes  with  very  little  fri Aion,  and  at  the  fiune  time  fo  hard,  as  (with 
due  care  in  ufing)  to  be  in  no  danger  of  being  blunted :  to  prevent  which,  the  inner  pillar  has 
a  motion  upwards,  as  has  been  faid,  by  the  fcrew  at,  and  by  means  of  a  iemi-circular  arm  at  its 
upper  extremity,  lifts  the  beam  of  its  bearings,  when  it  is  not  ufed,'  or  is  greatly  loaded.  This 
axis  is  placed  carefully  at  right-angles  to  the  beam ;  and  by  means  of  two  fmall  brafs  fprings 

5  A  fartber  account  of  theft  fcales  is  ^ven  in  the  appendix. 

Ihat 


that  prefi  gently  at  the  ends,  is  brought  ^vn,y%  to  have  the  (ame  bearing  tipon  the  cryftal ;  fo 
that  no  error  need  be  feared  from  a  fmall  deviation  from  the  right-angular  pofition  of  the  axis 
to  the  beam,  (hould  any  fuch  exift,  and  from  its  flnpe  and  quality,  it -may  be  confidered  as  in- 
flexible in  ordinary  experiments.     At  ^,  is  a  fmall  adjuftingfcrew,  which  raifes  or  deprefles  a 
weight  within  \  and  with  it,  in  confequence,  the  centre  of  gravity  in  the  whole  beam  \  by  this 
means  the  motion  in  its  centre  may  be  brought  ta  almofl  any  required  d^ree  of  fenfibility. 
Should  the  centre  of  gravity  be  raifed  above  the  centre  of  tnotion,  the  beam  would  turn  over ;  if 
it  be  in  that  centre,  the  beam  would  ftand  eVery  where  indifferently,  without  any  vibration ;  if 
it  be  placed  much  below  it,  the  vibration  would  be  too  quick,  and  its  fenfibility  not  fufficient ;  it 
is  therefore  brought  by  the  fcrew^  a  very  fmall  quantity  below  the  centre  of  motion,  fo  as  to 
defcribe  one  vibration  in  40  or  50  feconds :  the  fenfibilrty  is  then  fully  fufficient.     At  each 
end  of  the  beam  are  circular  boxes,  n  and  Oj  through  which  paf?  the  fbeel  centres,  from  whence 
are  fufpendcd  the  fcale  pans  q  and  r :  thefe  centres  referable,  fn  fome  degree,  thofe  at  i»,  but 
have  their  chamfered  or  angular  edges  upwards,  and  thereon  hang  the  hooks  j8,  to  which  are 
affixed  the  links  a,  and  to  them  the  three  ftlken  lines  of  the  (cafe.     Each  of  thefe  centres  has 
a  motion  in  its  rcf^e£tnr(e  box,  by  means  of  two  fmall  adjufting  fcrews  s  that  in  0  laterally,  and  ! 
that  in  n  vertically ;  the  former  to  make  the  two  arms  of  the  beam  of  an  equal  length,  the  latter 
to  bring  the  three  points  of  fuipendon  of  the  beam  and  (bales  into  a  right  line.     At  the  extre« 
mity  of  the  boxes  are  fixed  two  needle  points,  or  indexes,  which  play  againft  the  ivory  fcale  of 
divifion  at  s  and  /.     Thefe  divifions,  although  they  do  not,  indeed  they  c^not,  (hew  any  de- 
finite weight,  are  neverthelefs  very  ufeful  in  making  the  adjuftments,  and  even  in  weighing 
to  the  fmall  fraftions  of  a  grain,    ft  v  are  two  fteady  plates  that  are  raifed  br  deprefTed  by  the 
wooden  nut  uf,  to  check  the  vibrations  of  the  fcales  q  and  r,  and  bring  themfpeedily  to  an  equi- 
librium ;  y  z  is  a  table,  whereon  the  whole  is  placed,  to  raiie  it  to  an  hqight  convenient  for 
experiments*.  .  >      . 

To  ufe  with  this  beam  I  had  three  fets  of  weights  made,  viz. 

The  firft  fet,  or  feries,  of  fifteen  weights,  rifing  in  a  duplicate  progrelTion*  from  one  to  16384 
'grains,  viz. 

No.  '   Grains^. 

1  =        •        •        •    .     -         I 
a  =        -        -       -        -        2 

3  =        -        -        •       -        4 

'^  This  beam  is  conftruded  after  that  matte  by  RamfHen  for  the  Right  Honourable  Sir  Jofeph  Blanks,  Ban. 
P.R*S.  &c.  and  known  by  the  name  of  the  Royal  Society's  Balance.  It  is  to  be  regretted  that  wc  have  no 
good  account  of  that  infirurtenr.  The  chief  differences  between  this,  and  the  beam  defcribed  in  the  textf  are,. 
'  2,  that  certain  pieces,  or  rings,  fimilar  to  thofe  called  Jhps^  in  telefcopes,  are  driren  into  the  cones,  and  great!/ 
prorent  flexure,  by  prefenring  the  circular  feftion.  For  a  tube  can  fcarcely  bend,  unlefs  its  cavity  be  made 
to  change  its,6gure  ;  and  2,  the  planes  which  bear  the  fulcrum  are  fet  and  ground  together, '  and  are  levelled 
by  a  fpirit  level  placed  on  the  face  of  the  ftones|themfclYes.—X^ 

4  - 


tot 


EitpirimntU  u  ifitrtaU 


Ki. 

4 

5 

6 

7 
8 

SI 
12 

13 

14 


GratHS, 

« 

8 

Fra^km  rf  m  Grain, 

S6 

I 

3* 
<»4 

3» 

I 
iS 

ia8 

I 

s 

jia 

iot4 
2048 

.    I 

T 

r 
ft 

4096 

819s 

I*3«4 

Tbe  lecond  icrics  of  weights  in  an  aritbmetkad  oidco  as  fo&ows,  viz. 


\ 

Deemnl  FraaUns  afn  Grain^  viz. 

drains.. 

G^atMi 

Grains. 

1 

Grainsi 

^#V  fi4fmS9 

wr  »*•#•«• 

lootb  Grain. 

7>«f**. 

I 

10 

100 

1000 

lO« 

,10 

a. 

20 

200 

2000    , 

»oa 

,10 

3 

30 

J 

1O3 

.30 

4 

40 

4CX) 

4000 

,04 

.4« 

5 
6 

£ 

• 
600 

■ 

6000 

2J 

.SO 
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i 

1; 

>    800 

8000 

,08 

:£ 

9 

90 

( 

. 

»09 

»9®     « 

^ 

0 

I0»000 

N.B.  The  fndi- 

20)000 

cms  of  a  erain  are 
made  of  fine  wire 

The  third  fet  confifts  of  a  weight  oi 


1  ounce 

2  ounces 
4i>unces 
Bounces 
I  pound 


tfojr* 


*$  10.  akcdmi aid  (Plate  V.  fig.  5«)  is  the braft  cnbe ef  fire  inches^  Aatlias  been 
nentionedy  fu4)cnded  in  itt  own  Icsdes  by  means  of  four  fine  wires  £"001  the  arm  0  of  the  beatQ» 
fig*  4.  hy  taking  away  die  common  fcale  ar.  The^nte  refts  upon  aaradk^  or  crofs,  dme 
^rms  of  ^ich  are  ieen  at^  il  %  and  by  this  means  waej  be  weighed  either  In  air  or  watBr> 
%y  immerfion  into  die  large  glals  veflel  ^  A,  fig.  7. 

.  At  fig.  6  is  fecn  the  -cylinder  abc  i^nA  ai-td^  four  iadcs  in  duunctar  and  five  h^ 

Aung 


0  StanJifrd  •f  ffVgBi  and  Meafun.  itj 

flting  in  anodier  eradle,  part  of  whicb  is  (ixn  ztgbb  $^  Aipported  by  foor  wires  from  die 
point/; 

In  fig.  7,  is  feen  a  fphere  olF  brafs,  dy  fix  inches  m  diameter^  flung  in  a  cradle,  mbcyhy  tfiree 
wires*,  from  the  links  f^  fufpended  in  a  glafc  jarf ,  containing  near  four  gallons  of  water, 
whofe  temperature  is  (hewn  by  a  thermometer  at  e. 

§  1 1.  It  was  neceflary  to  meafure  the  exsft  fise  and  correfinefs  of  figure  of  this  fphere. 
For  this  purpofe  was  made  a  wooden  gauge  or  frame  a  b  c  de  (Plate  V.  fig.  a),  in  which  the 
fphere  was  placed  upon  femicircular  pieces,  within-lined  with  green  cloth  to  prevent  bmifing 
it;  upon  this  frame  was  placed  a  brafs  fquare  k  Imtiy  whofe  fides  were  about  xho  inch  in 
length  more  than  the  diameter  of  the  fphere.    This  fquare,  by  raifing  or  lowering  the  fcrews 
0  r  f,  was  eafily  made  to  coincide  with  a  plane  paffing  through  the  centre  of  the  fphere.    f 
is  a  micrometer  fcrew,  the  interior  extremity  of  which  is  brought  juft  to  touch  the  furfiice 
of  the  fphere,  while  tbe  oppofite  fide  bears  gently  againft  the  interior  fide  of  the  frame  at  o  ; 
and  by  turning  the  fphere  round  (b  as  to  pcefent  different  diameters  to  the(e  points  of  contad, 
any  variety  in  the  diameter  maybe  (een  by  the  index  /and  [date  f  divided  into  io,oooilis 
inch.    To  render  this  operation  more  convenient,  three  great  circles  were  drawn  with  a 
pencil  upon  the  fphere^^it  90^  diftance  from  each  other  (die  two  former  were  traced  by  the 
artift  in  the  lathe,  while  the  fphere  was  making,  and  the  third  was  drawn  from  them),  and 
each  was  divided  into  Z  equal  parts^     The  immediate  refult  of  dieie  experiments  would  only 
give  the  differences,  and  not  the  ablblute  quantity  of  the  diameter;,  for  this  purpoie,  a  brafs 
nilier,  r,  fig.  3>  was  made  of  fucb  a  lengdi  as  juft  to  go  within  the  brafs  frame  k  Imny  and 
being  fubftituted  in  the  place  of  the  fphere,  could  eafily  be  compared  with  any  given  diameter, 
and  afterwards  meafured  with  the  divided  fcale,  fig,  i.     With  thefe  inftruments  I  made  the 
following  obfervadonsy  Auguft  31,  1796^  the  thermometer  being  at  6i^ 

§  12.^  Examination  of  the  dimenfions  of  the  brafs  cube^  by  means  of  the  divided  fcale. 

The  microibope  and  micrometer  being  both  adjufted^  as  well  with  refpe£t  to  their  focus  % 

*  Thefc  wires  were  of  fuch  a  fixe  that  91  inches  weighed  10,71  grains,  confequently  i  incbaeo,s£76  grain, 
and  the  three  wires=o,6828  grain;  and  their  fpecific  gravity  being  8,?,  their  lofs  of  weight  by  finkbg  1 
inch  in  water,  would  be  0,0785.  grain.    This  oorreAton  it  may  be  neceflary  hereafter  to  attend  to. 

t  The  glafs  jar ismade  fcmewhat conical^ being  in 

Inches. 

Diameter  at  top        .•«...     12,0 

Ditto  at  bottom:  • 8,7 

Mean  dino  10,35 

Mean  height  within     •    ....     11,8 

Contents  in  cubic  inohct^    ».   _   •    .    991,78 

Which  is  in  aie.gallooa     .     •    .      =3,8aMi5j  quarts. 

It  may  aMb  be  noted,  thai  one  inch  in  depth«f  the  water  near  the  top  is  :»ii3  cubic  iachcv  which  is  equal 

in  the  exa£k  bulk  of  the  fphert, .as  will-be  feen  hercaf^r. 

Inchet-. 

'}  The  local  leag^  of  tha  otjeft.  lent  in       •    •    :ro^75 

Tht  diftance  of  the  crois. wires  from  the  objcft  lens       :si,oo 

The  focal  length  of  the  combined  tye-gla(s  ...••.••    8:i,l{o 

Whence  the  nai^ytngpawer  of  the  microfeope  becomes       ....    aai4ia  times. 

as 


104  EMperlmnU  U  n/cerimn 

as  to  the  value  of  the  micrometer  fcale,  the  crofs -wires  in  dieir  focui  were  removed  to  z 

'  diftance  from  each  other  of  five  inches  nearly  on  the  beam  (the  former  being  at  27,  and  the 

latter  at  32  inches),  and  then  comply  adjafted  to  this'  interval  on  the  divided  fcale*    I  muft 

obferve,  indeed,  that  the  value  of  the  micrometer  fcale  was  not  exa&ly  ten  revolutions  of  Ac 

fcrew  to  ,^0  inch,  as  Mr.  Troughton  defigned;  but  this  meafure  by  the  fere  w^,  from  6  trials, 

was  deficient  by  0,0002  inch ;  viz.  two  ten-thoufandths  of  an  inch  were  to  be  added  to 

each  tenth  of  an  inch  meafured  by  the  micrometer,  and  fo  in  proportion  for  a  lefs  quantity  ; 

but  this  correction  is  hardly  worth  notice. 

On  the  fcale.    Inches. 

The  interval  of  the  crofs-wires  in  the  microfcope')  Inch    Inch 

and  micrometer       -        -        -        -  5  27  and  32=5,0009 

Interval  of  ditto  on  another  part  of  the  fcale,"?  ^y-      . 

^  *^  '  (  26  and  31  =  5,0000 

viz.      ------  J 

Ditto  ditto        -----  25  and  3o=5',oooi  t 

I  therefore  fay,  this  interval  ,was   5  inches  corre£lly,  to  within  le(s  than  0xc  twenty-* 
thoufandth  part  of  an  inch  on  this  fcale. 

Meafurcment  of  the  cube,  viz.  of  the  fide  i  (fee  fig*  5«) 

Inches.  Mean. 

From  a  to  4=5—^0114  therefore  =  4998861        Inches. 

a  to  ^=5-^01 1 5   =  4,9885  I  _^    «oo 

.to  ^=S-,oi05  =  4,9895  f-*'988,82. 

*to  rf=5— ,0113  =  4*9387  J 

The  fide  2. 
From  a  to  ^=5 — ,0106 = —   =1  4,9894"! 

c  to //=5— ,0102 =  4,9898  f -♦'9»9SS 

d  toi/— 5— ,0112    >  =  4,9888  J 

Height  of  the  cube,  firom  fide  i  to  fide  2. 

Fromatodr=5 — ,0110 =  499890I 

b  to  A=5-,oi05 =  4>989S(  =4,98025+ 

c  to  i:=5— ,0107  =  4,9893  f  ~4jV09*^T 

^to^=5 — ,0108  —    —  =s  4,9892  J 

*  One  revolution  of  the  fcrew  of  the  micrometer  was  i^  inch. 
Each  grand  diviiion,  of  which  there  were  ten  .  •  ,J^  inch. 
Thefe  again  fubdivided  into  five  each,  became  .  .  ^^o  inch. 
And  half  a  divilion,  which  is  very  vifible,  ii .    .    .    ,^^0  inch. 

t  It  cannot  efcape  notice,  that  all  thefe  meafures  were  fomething  lefs  than  $  mchet,  the  quantity  propofed ; 
it  arofe  from  this,  Mr.  Troughton  informs  me,  he  was  more  folicitous  to  obtain  a  true  figure,  than  the  exadc 
fize  ;  neither  of  .vhich,  however,  were  very  important,' as  both  were  to  be  proved  by  the  mode  I  have  adopted. 
What  was  important  was  to  have  the  fides  true  planes,  and  thefe  were  exammed,  as  I  am  informed,  by  the 
reflc£ted  image  of  the  moon  fecn  through  a  large  tclcfcopei  the  focus  of  which  would  be  altered,  if  the  fur-* 
face  were  either  hollow  or  convex. 

*     §  13.  Now 


9 

a  itdniari  of  W^itght  md  Mtaptn.  105 

^13.  Now  the  three  foregoing  mean  meafures  of  the  fide  of  the  cube,  multiplied  into 
Tach  other,  will  give  =124, 189 17  cubic  inches  for  the  contents  of  the  brafs  cube,  which 
muft  be  very  near  the  truth  ;  for  if  not,  let  us  fuppofe  the  error  in  taking  each  of  thefc 
meafuretnents  to  be  half  a  thou(andth  of  an  indh,  which  is  much  greater  tha  n  is  probable, 
viz.=x^'cTyv  p^  ^f  (be  fide  of  the  cube ;  and  let  us  fuppofe  each  of  thefe  errors  to  lie  the 
lame  way,  which  is  alfo  very  Improbable ;  in  that  cafe,  the  error  in  determining  the  folid 
content  would  be_  only  to^  of  the  whole ;  in  the  above  inftance,  about  0^03  cubic  inch :  but 
more.prob^ly  the  error  does  not  amount  to  half  diis  quantity. 

§  14.  Examination  of  the  cylinder. 

The  micrometer  and  microfcope  of  the  divided  fcale  (Plate  V.  fig.  i.)  being  removed  till 
their  crofs-wires  were  four  inches  diftant,  viz.  from  54  inches  to  58  inches,  and  the  thermo- 
meter at  62^,  I  obferved  of  the  end  or  bafe  of  the  cylinder.  No.  i.  fig.  6» 

Indies.  Inches.        Mean. 

The  4iameter  4i  ^=4 — ,0027=73,9973 

e  ^=4—^0024=3,9976 

End  2,  of  the  cylinder. 

Inches.  Inches. 

The  diameter  a  *=4— ,0014=3,9986?  _         g^ 

c  </=4— »0029=3,997ii     ^'VV/«^ 

Height  of  the  cylinder* 

The  microfcope  and  the  micrometer  being  placed  reQ)e£Uvely  at  52,1  inches  and  581 1 
Inches,  viz.  at  the  interval  of  exa6Uy  6  indies  on  die  fcsde,  I  foand 

Inches.  Inches.  Mean. 

The  height  from  a  to  tf =6—^0049  ^  5>99S^ 

*  to  *=6— ,0047  =  S,99S3 
c  to  c=6— ,0047  =  S>9953 


1     Inches. 
X  =3.9974S 


Inches* 

i  to  ^=6-;^; "  •"''""  }► =5,99502 

Repeated 


6— ,005+  f 

»^«J^^J]=5,9944j 


2^ow  the  mean  diameter  of  the  cylinder  having  being  found 

Inches. 

At  the  end  1=3,99745 

At  the  end  2=3,99785 

The  fador  for  the  fquare  of  the! 

diameter  of  a  circle  to  find  the  >  =0,7854 
area,  being,  as  is  well  known,   j 

And  the  height  of  the  xyKnder      =5,9950. 

The  above  four  quantities  multiplied  into  eacli  other,  give  for  the  contents  of  this  cylinder 
in  inches=74,94823 ;  and  diis  refult  may.  be  taken  at  lead  as  corred  as  that  of  the  cube^ 
viz*  to  about  the  third*  place  of  decimals. 

§  15.  Hanring  acQufted  the  beam  of  the  balance  (fig.  4.)  with  refpa^  to  the  length 
Vol.  Ill— June  1799,  P  of 


xa6  •  £fcpifimtnts  maii  u  ajctruin 

of  its  arms,  tts^  centre  of  gravity,  and  the  three  points  of  fufpenfion  of  the  bquB  uA  id^ 
and  having  examined  the  weights,  I  proceeded  to  the  remaining  parts  of  this  experiment. 

September  2d,  1796.  The  balance-beam  adjufted  bj  the  fcrew/,  till  tke  vibrations  wefc 
fo  flow  as  to  require  more  than  50  feconds  of  time  for  each,  Vv  g»in  appeared  to  move  the 
index  through  three  divifions*  of  the  fcale  x  and  /,  =|  inch,  when  the  beam  was  not  loaded  ; 
but  when  the  beam  was  loaded  with  16384  grains,  or  near  31b.  troy,  tvv  grain  was  equ^ 
only  to  oh  diviflon  f  of  the  iame  (bale. 

%  1 6.  September  4th.  The  thermometer  being  at  63%  and  die  barometer  4t  29*36 
indies, 

Oz.  Grains^    Grains. 

The  weight  of  the  counterpoife  to  the  1 

pan  or  fcale  for  weighing  the  cube  in  (  =  1    75^02     =555,02^ 
air,  was  •         ^.         -  3 

To  which  the  weight  of  the  coauiioa*| 
pan,  with  the  fillcTines  on  the  left  arm  l 

of  the  beam,  and  marked  widh  jr,  the  V-**^  ■   •    C4i3»4a 

common  right-hand  pan  having  been  I 
removed  -        -  -  J 

And  the  whcde  weight  of  Ae  pan  or  ap-1 
^  paratus  for  weighing  the  cubt  in  aify  >  — ^       ■  5:969,42 

becomes  *         ""  •  j 

§  17.  The  counterpoife  to  the  pan  or  1 
fcale  for  weighing  the  cylinder  in  ain  r  =x     72,34    =552,34 
was  found  •         -       '    -  ^ 

To  which  add  the  weight  of  the  com»?  ._^    —  ra  ao 

mon  pan  on  the  left  arm,  as  before       3  ""^  •  J 

And  the  whole  weight  of  the  pan  or  fcale  1 

for  weighing  the  cylinder  in  air  Ije-  >  — •      =965,74 

comes  -  -         -  3 

JNote^  in  the  preceding  and  fuch-Kke  experiments,  the  common  right-band  fcale  bein^ 
removed,  and  die  left-hand  fcale  being  always  ufed  and  always  the  £une  weight,  viz.  41394a 
grains,  when  either  the  cube  or  cylindei^  or  any  large  body,  is  weighed,,  notice  need  only  ta 

•  Twenty  divifioni  arca»i,o  inch.  , 

f  That  is,  the  beam  was  fenfible  with  ,cJ^  part  of  the  whole  weight.  Mr.  Harris's  beam,  with  which  he 
and  Mr.  Bird  made  their  obfenrations  on  the  cxchequtr  weights,  turned  with  ^,^  part  of  the  whole  weighr^ 
and  was  confequtntly  only  one  )  part  To  fenfible  as  this..  See  **  The  Repdft  of  the  Committee  of  the  Houfe 
*<  of  Commons  in  1758^,  to  inquire  into  the  original  ftandards  of  weights  aad  mdUiires  itfthis  kingdom,  and 
**  to  coniider  the  laws  relating  thereto.*'  See  alfo  a  (econd  Repon  in  1759  ;  both  of  whicb  contain  a  vafi 
deaVof  ufefol  information  on  this  fubje6^,  extending  through  fifty  folio  pages»  and  are  to  be  found  in  the  zd 
Yol.  of  Reports,  from  1737  to  1767.  A  bill  was  brought  in,  in  canfequencey  but  aftrrwirds  dropped ;  and  it 
13  much  to  be  lamented  that  this  inquiry  did  not  go  to  the  full  length  of-  an  a£t  of  Parliament.  Note  farthcr« 
the  largeft  of  the  beams,  of  which  there  ar^  fome  of  different  fixes  now  mfde  ufe  of  in  the  duchy  court  of. 
Lancafter,  for  the  a6hial  fizing  of  the  weights  of  the  kingdom,,  is  about  three  feet  long,  and  is  moveable  with 
about  30  grains  when  561b.  avoirdupois  are  in  each  fcale,  viz.  about  ^^  part  of  the  whole.— G«  8.  £.«-^ 
An  acQOU^i  •f  nine  othrr  balances  x^ay  b^  feen  in  »y  Firji  PrincifUt  9f  Cbmifi^j  ciiip.  VL-«*-N« 

•  be 


a  Standard  rf  tVttght  and  AHiafures  '  107 

t>e  taken  ofcdie  cotmterpoife  weight,  vix.  555iOt  grains,  or  552,34  grains  refpediively ;  and 

^efe  are  to  be  deducted  from  die  general  amount  of  all  the  weights  in  the  left-hand  fcale 

marked  x ;  but  it  certainly  would  have  been  more  convenient  to  have  had  fingle  weights 

ready  adjufted  for  diefe  counterpoises,  both  in  air  and  water.    Thefe,  diough  at  firft  omitted, 

'liave  fince  been  Supplied.  ^ 

Grains. 

5  18.  TTie  counterpoife  to  the  fcale  for  (he  cube^  —  aai  tc 
in  diftilled  water,  with  the  heat  of  61^       -         3  —^  »/5 

To  this  add  die  weight  of  the  common  fcale  as  before =4 13,40 

And  we  Jiave  the  whole  weight  of  the  fcale  for7  _o-g  ,. 
the  cube  in  water         •  -  •  ^ —oS^*  S 

But  the  weight  in  air  having  already  been  found      =968,40 

The  diflperence  of  the  weights        -        -         -         =112125 

Gives  for  the  fpecific  gravity  of  this  brafs       *         r:    8»6t 

§  19.  The  counterpoife  to  the  fcale  for  the  cy-^  «.j. •  go 
Under,  in  the  fame  water  with  the  fame  heat     3  ""       * 

To  this  add  die  weight  of  the  common  fcale  as  before=4 13,49 

And  the  whole  weight  of  the  fcale  for  the  cylinder  1  _q^- qQ 

in  water  becomes  -  -  -  5"" 

Its  weight  ia  air  has  already  been  found         «  =965,74 

The  difference  of  diefe  weights  -         -  =110,66 

Gives  for  the  fpecific  gravity  of  this  brals  -  =    8,78 

The  mean  fpecific  gravity  of  this  brafs,  and'brafe-?  —      8«7 
wire,  may  therefore  be  put  about  -  ^  ^-      "»/ 

.  N.B.  The  titbles  of  fpecific  graritj^  give  that  of  wrought  braft  «firem  8,00  to  8,2a 
It  was  neceflary  to  afcertain  the  fpecific  gravity  of  Ae  bra&  wire,  to  make  the  corredion 
mentioned  in  the  note  to  §  10 ;  for  as  it  was  highly  poffible  that  in  experiments  with  thi$ 
hydroftadc  balance,  the  fcales  for  the  cube  and  cylinder  would  occafionally  be  immerfed  tm 
<Iifferent  depdis  in  the  water,  and  dieir  weights  would  be  altered  as  more  or  4els  of  the 
Vikes,  by  which  they  were  fufpended,  renmined  out  of  Ae  water. 

Grains, 
laccordingly  found  diat  80  indies  in  lengdi  oi 
this  wir^,  lifed'  in  thefoales  for  die  cum  and 
cyliofiex^  weighed  m  air 

Atidconfequently  i  indfa  would  be  =0,077  ff^^^»  ^  ^^^^  wires  of  i  indi  =,308  graii^ 
which  divided  by  the  fpecific  gravity,  vis.  ^ ,  would  give  0,0354  grain  for  tfie  correftioa  ^ 
•veqr  inch  diat  the  fcale  wis  funk  lower  in  die  water;  and  fo  in  proypodjioiL 

(Ta  bttMtinuid^J 


208 


(h  tbi  DiJUviriis  tf  May9W» 

n. 


Litter  fromDr.  Beddoes  n^e^ing  Gt.  FouRCRor^s  Account  of  tbi  Dlfcoviriis  ofMATOnrm 

To  Mr.  Nicholson. 
Sir,  May  id,  1799. 


I 


T  would  be  eafy  to  write  a  comment  upon  Mr.  Fourcroy*s  expefition  of  the  merits  of 
Mayow,  as  long  as  the  expofition  itfelf  (fee  Annales  de  Chimie,  No.  85) ;  I  wi(h,  how- 
ever, to  fubmit  only  two  or  three  remarks  to  that  author's  candoiur.  From  unremitting  oc- 
cupations of  a  more  important  nature,  Mr*  F.  was,  I  fuppofe,  prevented  from  bedowing 
much  time  upon  Mayow.  Marks  of  hade  and  of  want  of  information  are  very  apparent. 
I  will  not  inflft  upon  fuch  an  error  as  tranflating  taidai  firali'^^orcbe  crueUi^  or  upon  the 
wrong  aflertion  that  I  republifhed  Mayow  in  1790.  In  general,  the  French  author  has 
bellowed  ample  praife  upon  our  countryman;  but  in  the  eftimate  of  his  underftanding  he 
has  &iled  moft  materially.  He  has  neither  entered  into  his  views  nor  rightly  conceived  the 
fyxtit  with  which  Mayow  laboured.  Mr.  F.  fiiys,  that  tbi  thread  wbicb  be  found foon  broke 
in  his  bands  \  that  be  did  not  fufpe^  the  extent  of  the  career  wbicb  be  opened  \  and  that  he  was 
not  fufficientlj  Jlruck  with  the  Jingularitj  and  importance  of  bis  prfl  cRfioveries  (p.  89).  It 
would  be  extraordinary  indeed,  if  a  peribn  who  outftripped  his  age  in  a  degree  of  which 
there  is  no  other  example  in  the  hiftory  of  fcience,  had  not  been  endowed  with  fuperior  com- 
prehenfion  of  mind.  And  Mr.  F.  is  dire£lly  contradided  by  Mayow's  dedication.  Never 
was  a  fenfe  of  the  importance  of  a  man's  writings  more  fervently  cxprefTed,  **  ^a  autem 
^  de  Nitro  fcripjimusy  ea  fe  per  univerfam  fere  naturam  diffundunt !  refque  abjirufas  explicant 
^  quarum  plerafque  e  numerofd  fcriptorum  turbd  vix  quifquam  attiget :  and  (b  on.  HadMr.  F. 
known  that  Mayow  died  at  27  or  28,  he  would  not  perhaps  have  talked  of  the  diread  breaking 
in  his  hands,  and  of  his  only  opening  the  career.  What  Mr.  F.  advances  concerning  caufes 
of  the  greater  populiarity  of  BoyTe,  appears  to  me  ill  founded.  But  I  will  not  encroach  upon 
your  Journal*,  by  any  further  obfervations,  uide(s  you  or  your  readers  defire  it. 

I  am,  Sir,  jour  humble  fervant, 

THOMAS  BEDDOESJ 


III. 

Obfervaiions  and  Experiments'  on  various  Saponauouf  Ctmpoundt^' farticularlft  tbi  Fijb  Soap  of 
Sir  John  Dalrtmfle.    By  Afrr.  Robert  Jamxson  F.L.S.  feV. 

SlR» 


I 


INCLOSE  you  a  paper  on  the  making  of  Soapi  from  Fifli,.  a  fcheme  which  has  beea 

for  fome  time  the  objeA  of  very  confiderable  attention  in  this  part  of  the  ifland.     As  many 

feem  to  view  it  in  a  more  fiivourable  light  than  it  deferves,  I  conceive  it  to  be  doing  juftice  ta 

the  public,  to  publifli,   through  the  means  of  your  excellent  Journal,  a  fair  ftatement  of  its 

plaufibility.  i  am,  with  refpeft,  Sir,  your  obedient  fervant, 

ROBERT  JAMESON. 
Sheriff  BraC)  Lcitb^  AUy  i^tb,  1799* 

TaMr.  NicHOLSoK.  On^ 


•< 


I 

Hijlorj  of  tbi  tf  Aft  tf  Soap^mahi^g.  109 

On  SoaPf  and  particularly  the  Combination  nf  Fijh  andPotaJhy  called  Fijh  Soap. 

The  utility  of  this  fubftance  mud  have  made  it  an  obje£l  of  early  attention,  for  as  man- 
kind advanced  in  civilization,  and  ailbciated  in  villages  and  towns,  faponaceous  matter 
became  neceflary,  not  only  foH  the  purpofes  of  cleanlinefs,  but  for  other  cotemporary  arts. 
Although  this  Teems  to  be  the  probable  origin  of  the  manufaAure,  we  have  no  written  re- 
cord of  its  ufe  until  die  time  of  Pliny,  who  attributes  its  invention  to  the  Gauls.  Their 
foap  feems  to  have  been  a  compound  of  tallow  and  potafli,  for  Pliny  obferves,  that  it  was  made 
6(  taflow  and  aflies,  but  the  beft  of  goats*  ullow  and  the  afhes  of  the  beech-tree.  Befides 
this  foap,  we  have  early  accounts  of  the  ufe  of  different  deterfive  fubftances,  particularly, 
aQies  of  vegetables,  natron,  and  urine ;  feveral  of  the  ancient  writers  mention  faponaceous 
vegetables,  that  appear  to  have  been  ufed  for  cleanftng  clpthes.  Beclcman,  profeiTor  of  eco» 
nomy  at  Gottingen,  is  led  to  fuppofe,  on  the  authority  of  Strabo,  that  bran  was  employed 
by  the  Romans,  for  the  purpofes  of  wafliing  fuch  cloth  as  would  be  injored  by  the  hard 
rubbing,  and  ftrong  deterfive  power>  of  an  alkali  or  common  foap. 

The  Romans  alfo  ufed  different  natural  combinations  of  the  argillaceous  eartfr,  for  the 
purpofeof  fulling.  Thefe  were  imported  from  different  countries,  as  the  Chia,  Lemnia,  Sarda, 
Samia,  &c.  They  varied  much  in  their  deterfive  power  :  the  beft  and  moft  valued  was 
named  cimolia.  This  has  been  confidered  by  feveral  mineralogifts,  as  the  fame  with  our 
fullers-earth ;  but  Mr.  Ha\^ins  has  lately  difcovered  the  true  cimolia  of  Pliny,  which  is 
very  different  from  the  fullers«^arth)  upon  the  ifland  of  CimolO|  or  what  is  now  denominated 
Argeijtie'^a*. 

Durmg  the  courie  of  ages,  feveral  alterations  have  been  made  in  the  art  of  foap-making ; 
but  thefe,  like  many  other  improvements^  have  occurred  acckfentatly  to  the  manufadiurer,  who 
in  general  was  bat  ill  qualified  to  make  the  beft  ufe  of  them.  Their  prejudices,  and  the 
vague  general  knowledge  of  the  man  of  fcience,  have  been  the  greateft  bars  to  improvement. 
Happily,  circumftances  are  now  altering,  the  artift  and  the  philofopher  are  combining  their 
efforts  to  improve  the  manufactures,  and  to  eftablifh  fuch  a  connexion  among  them  as  will 
\t  for  dieir  mutual  advantage.  The  great  inftitution  now  forming  in  London,  will  contri- 
bute very  much  to  this  end,  and  afford  us  another  proof  of  the  fuperiority  of  the  Britilh 
nation,  in  every  thing  regarding  the  improvement  of  manufadlures. 

The  accounts  which  have  been  publifhed  of  the  procefs  for  foap-making,  are  in  general 
vague,  and  often  dontradiClory.    The  report  in  the  19th  vol.  of  the  Annales  de  Chimie,  is' 
the  moft  complete  treatife  that. has  ever  appeared  upon  this  fubjedb,    It  is  a  model  which 
deferves  to  be  imitated,  not  only  for  the  accuracy  of  the  details,  but  the  comprehenfive 
manner  in  which  the  whole  is  treated* 

Different  Kinds  of  Soap* 

I  cannot  pnetend  to  enumerate  in  this  paper  all  the  kinds  of  foap  which  are  now  manu^- 
faAured,  but  will  only  mention  the  moft  important 

•  Piiniut  hift.  nat.  lib.  ssiCap.  57.— AgricoU  dc  naturlFtiT.  lib*  *.— Lenz.  Mincralogiftcs  Hand-buch. 
Emntrloig,  Lehrbucb,  vol.  3,-^Kiaproth.  Bcitrage, 


no  Cifi^cfiism  and  Pt$€ifiS  fir  making 

In  France,  both  bard  and  Toft  foaps  art  manufa&ured  in  very  confiderable  quantity,  l>ut  the 
hard  foap  is  the  moll  generally  ufed.  The  hard  foap  is  principally  made  from  the  oil  of 
olives  and  bariUa,  and  it  is  found  that  twelve  hundred  weight  of  oil,  with  a  fuffident  quah* 
ticy  of  barilla  ley,  forms  a  ton  of  foap*.  Manufacturers,  however,  do  not  always  reft  con«» 
tented,  with  fuch  a  return  >  but  by  ufmg  many  unwarrantable  pradices,  tncreafe  the  weight 
y  of  the  foap,  without  adding  to  its  value  as  a  cleanfer.     Thus   we  are  told  in  the  French 

reports,  diat  Quefnot  has  publi(hed  a  method  of  increafing  the  weight  of  foap  in  a  four-fold 
proportion.  This  he  does  by  mixing  with  it  alumen,  muriate  of  foda,  ftarch,  chalk,  foda  in 
powder,  oil,  tallow,  and  water  i  and  this  ftupid  procefs  he  announces  under  the  title  *'  Dg  bitti 
augmentation  defavon.** 

.  In  J^rance  the  foft  foap  is  made  with  potafh  and  different  vegetable  oils,  as  oil  of  turnip, 
hempfeed,  Untfeed,  &c. 

In  Hungary,  foap  is  made  with  tallow  and  natron,  according  to  Townfon,  who  has  given  us 
a  vague  account  of  their  method  of  manufadure.  Ill  many  parts  of  Germany  and  Ruffia, 
tallow  foap  is  manufactured  ;  and  in  Ruffia  a  good  hard  foap  is  made  with  butter:  the  butter - 
which  is  ufed  for  foap  making,  is  in  general  damaged*  iidt  batter,  which  does  not  make  a  pro- 
fitable foap  ;  this  is  owing  to  its  rancidity,  and  die  quantity  of  £dt  and  cheefy  matter  dif- 
fufed  through  it.  Weigleb  aiTures  ui  that  a  foap  is  manu&i£hired  with  yellow  and  wlute  wax, 
which  is  hard  and  firm,  with  an  agreeable  fmell  like  almonds. 

As  no  confiderable  quantity  of  vegetable  oil  can  be  procured  in  Great  Britain,  our  (bap  it. 
always  made  with  tallow,  or  fiih-^1 ;  fometimes  alio,  the  refufe  of  kitchens  and  rancid  butter 
have  been  ufed.  The  foaps  manufactured  in  the  great  way  are  white,  mottled,  yellow,  anA 
foft  foaps. 

!•  Whiii  Soap.  This  is  made  from  tallow,  with  a  ley  of  barilla,  or  kelp ;  the  tallow  is  rec*' 
kpned  good  if  i^cwt.  with  the  proper  proportion  of  ley,  affords  a  ton  of  ibap.  It  is  the; 
moil  expenfive  of  the  hard  foaps,  and  is  principally  ufed  for  the  finer  kinds  of  work. 

2.  Mittiid  Scap.  This  is  the  next  in  value,  and  is  manufiiftured  from  tallow,  kitchen-fhi^. 
and  barilla.  The  mottled  appearance  is  given,  towards  the  end  of  the  operations  of  boiling^ 
by  difperfing  the  ley  through  the  foap.  In  France,  they  follow  ^  method,  which  is  more^ 
fimple,  and  furely  more  fuccefsfiil.  Their  method  is  as  follows :-— After  die  foap  has  been  fo* 
farated  from  the  wafte  ley,  it  is  boiled  again  with  a  freih  portion  of  cauftic  ley,  then  a  quan* 
tity  of  the  folution  of  fulphate  of  iron  is  added,  which  by  its  decompofiU(m>  depofits  its 
oxyd  through  the  foap,  gi^ng  it  a  blui(h  colour.  The  foap  is  now  allowed  to  cool  flowlj,. 
when  it  rifes  above  the  wafte  ley ;  this  ley  is  then  drawn  off,  and  the  foap  melted  by  itfel^  * 
before  cafting  into  frames. 

3.  Tiilew  Hard  Soap^  is  made  with  tallow  and  rofin;  and  tiiefo  are  icchoiiedl -good^  il 
loctvt.  of  tallow,  34^ti;/.  of  rofin,  with  the  proper  quantity  of  barilla,  or  kdp  ley,  afibrd  a  ton 
of  foap.  The  rofin  is  ufed  merely  to  cheapen  the  foap,  for  it  certainly  does  not  increafe  its 
power  as  a  cleanfer.  Rofin  and  alkaK  boiled  together,  without  taUow^  foim  n  vifcid  tern* 
cioos  mais,  of  a  very  inferior  nature  as  a  cleanfer. 

K  *  Annakt  4e  Chisue,  toI.  99. 


*    1- 


thi  tmrims  j^Mdf  jof  Snip.    "  .  .    ttt 

4.  iefi  Soapf  ts  made  with  whale  or  fifli  dl;  but  I  am  not  acquaint  widi^e  proportion 
ttfed.  The  procefs  for  making  it  differs  frpm  that  of  hard  foap,  in  diis  circumftance,  that 
none  of  the  ley  is  drawn  off*,  but  the  whole  is  allowed  to  combine  with  the  feapy  compound. 
On  diis  account}  it  is  neceflfary  to  ofe  a  pretty  pure  alkali,  particularly  that  it  (hould  be  free 
from  iea*falc,  which  is  a  tubftance  of  the  greateft  detriment,  as  it  caufes  the  foap  to  feparate 
from  the  ley,  and  rife  to  the  top  of  the  vefTeL  The  oil  and  alkali  ( whldi  muft  be  pot-a(h) 
are  boiled  together,  until  a  cojpbinatioh  has  taken  place ;  then  a  quantity  of  tallow  is  added, 
which,  by  particular  management,  is  difperfed  through  the  foap,  in  the  form  of  white  fpots, 
giving  it  a  beautiful  appearance  *.  ' 

Having  thus  curforily  mentioned  the  principal  kinds  of  foap  manu&dured  in  different 
countries,  I  will  now,  in  as  few  words  as  poffible,  ffate  the  procefs  folbwed  in  this  cduntry, 
for  making  common  white  foap.  This  will  enable  us  to  judge  with  more  certainty  of  the 
pbui  lately  propofed  for  making  hard  foap,  by  mixing  the  mufcular  fibre  of  fifh  with  the 
tallow. 

Procefs  fir  making  White  Soap. 

The  tallow  is  firft  melted  in  the  veffel  with  weak  barilla  ley,  the  mixture  is  then  gradually 
brought  to  a  boiling  heat,  and  we  continue  adding  alkali,  until  the  whole  of  the  tallow  has 
formed  a  faponaceous  compound.  We  know  this  has  taken  place,  if  the  compound  has  a 
milky  appearance,  widi  a  confiderable  degree  of  coniiftence,  and  feems  to  be  feparating  from 
tiie  liquor  below.  This  feparation  is  a  very  material  part  of  the  operation ;  and  to  efFedk  it 
completely,  a  quantity  of  fea-falt,  or  weak  kelp  ley,  is  added,  the  materials  are  continued  boil- 
ing for  two  or  three  hours,  and  then  the  fire  is  withdrawn.  The  foap  will  now  be  found 
united  at  the  top  of  the  liquor>  or  what  is  called  the  wafte  /ryf,  which  is  of  no  further  ufe, 

and 

*  I  fliould  be  happy  to  learn  the  proponions  ufed  in  foft  foap  making,  and  alfo  the  particular  management 
of  the  tallow  in  producing  the  white  fpots ;  and  if  this  tallow  be  of  any  fervice. 

\  The  ley  which  it  found  below  the  foap,  and  known  under  the.  name  of  wafte  ley,  is  of  a  rery  mixed 
nature,  and  the  variety  it  much  increafed,  according  as  potafh,  barilla,  or  kelp,  are  ufed  in  the  manufa^ure. 
Several  fobftancet  alwayt  occur,  whatever  be  the  nature  ^  the  faline  compound  employed.    Thefe  are, 

K.  GeUuine,  A  confiderable  quantity  of  this  fubftance  (which  had  bcen.previoufly  combined  with  the  tal- 
low) is  found  ro  folution,  or  fufpended  in  the  ley :  the  caudic  alkali  has  fo  firong  an  a£tion  upon  it,  that  a 
portion  is  decompofed,  the  hydrogen  and  azote  flying  oflf  in  the  form  of  ammonia,  while  the  carbonaceous 
matter  remains  behind,  giving  a  dark  blue,  or  blackiih  colour,  (o  the  undecompofed  gelatine. 

a.  As  tallow  contains  febacic  acid,  it  unites  with  the  alkali,  and  fometimes  with  the  lime,  forming  fcbats» 

3^  Carbonate  or  uncombined  alkaliJ  However  accurately  the  manufa£turer  works,  ftill  a  quantity  of  the 
alkali  elcapes,  and  it  found  in  the  wafte  ley.  Befides  the  fubftances  we  have  already  mentioned  to  be  com- 
viOD>  other  combinations  occur.  Thus  if  kelp  be  ufed  alone,  in  making  the  foap,  betides  the  gelatine,  &c 
the  ley  contains  muriate  of  foda,  fulphate  of  foda,  fulphurets  of  foda,  and  potalh.  As  pota(h  is  never  worked 
by  itfelf  in  making  hard  foap,  but  generally  with  kelp  (ac  leaft  in  Scotland),  we  obtain  diflferent  (aline  com- 
ynations  *,  thefe  are  muriate  of  potafli,  muriate  of  foda,  and  fulphate  of  foda  ;  but  this  laft  is  in  fmall  quantity  : 
fvlphuret  of  foda  alfo  occurs.  If  barilla  is  employed,  we  have  muriate  of  foda,  fulphate  of  foda,  and  folphuret 
of  foda,  11^  the  ley.  The  nature  of  the  faline  compounds  found  in  barilla  ley,  are  often  confideiiibly  different 
fforn^  what  has  been  now  mentioned  \  particularly,  whea  the  foap  is  made  with  Catalonia  barilla.    This  it 

owiag; 


lit  iulfikHiis  fi^  Talhw.    S^ap  ff  Fljh. 

and  IS  therefore  to  be  drawn  off  bj  a  pump  or  fyphon.  The  Toap  is  now  melted  for  die  laft 
time,  with  a  finall  quantity  of  water,  or  Mvhat  is  better,  weak  kelp  ley ;  it  is  then  allowed  to 
cool  for  a  ihort  time,  and  afterwards  caft  into  frames.  The  melting  with  water  is  of  con* 
fiderable  importance,  as  it  gives  the  ibap  a  fmooth  and  compadl  appearance,  or  what  the  work- 
men term  a  flcin. 

Having  premifed  this  much  with  regard  to  the  different  kinds  of  foap,  which  are  already 
'known,  I  will  now  proceed  to  confider  the  plaufibility  of  a  late  propofal,  for  the  manu&£hir- 
ing  of  foap  with  fi(h  and  tallow,  or  by  ufing  fi(h  alone,  diflbred  in  potafli. 

Attempts  have  been  made  at  different  times  to  procure  a  fubftitute  for  tallow  ;  but  in  no 
inftance  has  it  been  attended  with  fuccefs.  Several  years  ago, .  when  the  Greenland  fifhery 
was  more  confiderable  dian  it  is  at  prefent,  foap  manufacturers  ufed  a  confiderable  quantity 
of  oil,  in  making  their  hard  foap ;  but  the  ftrong  oily  fmell  foon  deftroyed  its  .(ale,  and  feveral 
ibap-makers  were  fubjeded  to  confiderable  lois.  It  is  to  be  regretted  that  this  attempt  was 
not  attended  with  fuccefs,  particularly  when  we  confider  the  great  advantages  wHich  would 
refult  from  the  increafe  of  our  Greenland  ikBitTy^  by  the  diminutipn  of  die  importation  of 
tallow  from  Rui&a*. 

During  the  courfe  of  the  laft  year.  Sir  John  Dahymple,  Bart,  one  of  the  barons  of  ex- 
chequer,  obtained  a  patent  in  the  name  of  John  Crooks,  for  a  new  method  of  making  foap* 
He  prcpofed  to  ufe  the  mufcular  fibre  of  fifli  in  a  certain  proportion  with  tallow  to  make 
hard  foap,  and  to  fubftitute  it  for  oil  in  the  manufadure  of  foft  foapf*  As  this  fcheme  pro- 
mifed  to  be  of  the  greateft  national  importance,  it  was  taken  into  confideration  by  the  Houfe 
of  Commons.     Soon  afterwards.  Sir  John  Dalrymple  was  examined  by  a  conunittee  of  the 

owing  to  a  method  thty  employ  of  adulterating  ir,  by  burning  along  with  the  SaHbla  foda  different  fpccies 
of  fuci.  In  London,  a  barilla  is  made  by  mixing  together  Alicant  barilla  and  kelp ;  and  this  is  termed  Britifli 

barilla. 

'*  The  importation  of  tallow  from  Ru(!ia  is  ftated  to  be  about  one  million  fterling  yearly. 

+  The  difcovery  of  the  converfion  of  the  mufcular  fibre  into  a  fubftance  refembling  fpermaeeti,  has  aflforded 
room  for  confiderable  fpeculation,  as  to  the  probable  advantages  mankind  may  derive  from  it.  The  anuziag 
number  of  animals  killed  in  different  countries,  for  the  fake  of  their  fkin  and  tallow,  has  been  Ticwed  at  likely 
to  afford  a  means  of  procuring  this  fubftance  at  a  cheap  rate.  A  more  plaufible  method  of  rendering  this  in- 
terefting  difcovery  of  ufe,  may  be  found  in  employing  fiih  in  place  of  the  mufcular  fibre  of  land  animals.  la 
Scotland  particularly,  this  fpeculation  deferves  attention,  as  the  quantity  of  fi(h  which  fills  our  (ea  at  different 
times  of  the  year  is  very  great.  Thus  the  herrings,  which  yearly  arrive  upon  the  coaftt  of  Scotland, 
would  afford  a  great  foQrce  of  animal  matter  for  this  purpofe ;  alfo,  the  dog  fifli,  which  are  fo  obnoxious  to 
fi(berF,  might  be  taken  in  immenfe  quantities ;  and  after  they  had  afforded  their  oil,  might  ferve  for  the  pur- 
pofe of  aff*ording  fpermaccti.  The  coafts  of  Scotland  are  alfo  happily  conilitoted  for  this  branch  of  induftryp 
owing  to  the  number  of  running  waters,  which  we  find  almoft  in  every  quarter  5  thefe  might  be  eafily  turned 
in  different  directions,  and  employed  to  run  over  a  great  quantity  of  animal  matter.  The  advantages  at- 
tending a  fuccefsful  cultivation  of  this  difcovery  in  the  Highlands  of  Scotland,  are  numerous  and  important ; 
but  they  cannot  be  detailed  here.  It  is  an  object  worthy  the  attention  of  the  Highland  Society  of  ScotUnd, 
which  has  already  done  much  for  the  intereffs  of  that  part  of  the  iffand.  If  premiums  were  off*ered  with  this 
view,  wc  ihould  foon  have  the  whole  tried  experimentally* 

Houie 


AfiihiJs  of  making  Soap  of  tifih.  J13 

H<H^  vh^  ^  detailed  the  value  of  the  &ippofed  improvement  in  fuch  ftrong  terms,  Aat  an 
^rder  was  given  by  the  Lords  of  Trade  and  Plantations  to  have  the  whole  determined  by  a 
Ucilful  manu&^rer,  in  the  neighbourhood  of  fome  fiihing  ftation ;  and,  in  compliance  with 
.  this  order,  the  Honourable  the  Board  of  Trudees,  at  Edinburgh,  requeiled  my  fiither  to  make 
the  neceflary  trials,  and  report  for  their  fatisfatStion.  Thefe  experiments  were  made  as  fooii 
as  circumftances  would  permit ;  and  the  refult  has  been  lately  laid  before  the  board.  As  thi^ 
report  contains  a  (atisfaftory  feries  of  experiments,  I  will  now  lay  before  the  public  a  few  of 
them,  with  the  view  of  fetting  this  fuppofed  improvement  in  a  proper  point  of  view. 

Previous  to  this,  I  (hall  mention,  in  as  few  words  as  poffible,  the  procefles  followed  by 
Sir  John  Dalrymple  in  making  hard  and  foft  foaps  ♦. 

To  make  Soft  Soap,  The  fifli  are  firft  to  be  well  wafhed  in  water,  to  free  diem  frpm  blood, 
&c.  and  are  then  to  be  thrown  into  a  boiling  folution  of  cauftic  potafh,  in  the  proportion  of 
front  fix  ta  ten  parts  of  fifli  to  ten  of  alkalis  The  fefli  being  diffolved,  tallow  is  dien  to  be 
added  in  the  proportion  of  one  part  to  eight  .of  fiflt.  Thefe  being  boHed  together  for  fome 
time,  turpentine  is  added  in  the  proportion  of  one  part  to  fixteen  of  foap  j  afterwards,  a  36tli 
part  of  palm-oil  is  added,  to  give  the  foap  a  better  colour.  The  foap  being  finifbed,  it  is  to  be 
ipread  about  two  inches  thick  in  a  cool  place,  and  kept  there  for  a  month  before  beii^  ufed  ; 
during  this  time,  it  muft  be  turned  every  two  or  three  days  with  (hovels  or  hoes* 

To  make  Hard  Soap.  Having  diflTolvcd  a  certain  quantity  of  fi(h  in  cauftic  vegetable 
alkali,  an  equal  quantity  of  tallow  is  to  be  added,  and  to  be  continued  boiling,  until  they  arc 
completely  united.  The  vefTel  is  then  flowed  to  cool,  and  mineral  alkali,  or  mineral  and  ve- 
getable alkali,  and  rofm  are  to  be  added:  the  alkaline  ley  in  the  proportion  of  five  parts  to 
twenty  of  fi(h  and  tallow.  The  whole  is  .then  to  be  boiled,  and  in  an  hour  after  the  ftrongefl: 
wafte  ley  is  to  be  added  in  the  proportion  of  two  parts  in  weight  to  25  parts.  The  whole  is 
then  to  be  boiled  until  the  alkali  has  united  with  the  vegetable  and  animal  matters.  The  ley  is 
now  to  be  pumped  off,  and  cauftic  mineral  alkali  added^  in  the  proportion  of  three  parts  iji 
weight  to  25  parts ;  and  the  whcde  is  to  be  boiled,  until  a  good  foap  is  formed :  laftly,  the  foap 
is  to  be  melted  in  water,  and  caft  into  frames. 

We  need  not  ftop  to  examine  the  proceflTes  here  detailed,  as  they  muft  appear,  from  what 
lifls  been  already  ftated  with  regard  to  foap.«iaking,  to  be  very  incorred; 

As  the  report  given  to  the  Board  of  Truftees  contains  a  long  (cries  cf  experiments,  it  wbuli 
occupy  too  much  room  to  infert  Aei^at  full  length ;  1  (hall,  therefi^rCr  only  abftradl  thofc  whk& 
^peartoiie  the  moft  kr^KHTtant. 

Hard  Snap  from  Fijh^  i^c. 

Ekfbrimbnt  I.  . 


- 

•             Ok>t.  tfrT.  Ar 

Herrings 

Talbw 

Rofin 

5      2     20 

-    '    -       -       -5      3  '    8 
*-      ^-       •*        r      a 

^E  i799« 

*  This  is  abridged  from  his  patent. 

Q.' 

.» 


rh€Ce 


X 14  Expninuntal  Enquiry  tnU  the 

Thefe  fubftances  were  boiled  together  lb  as  to  form  a  (bap,  and,  after  cafting  intQ  framety 
afforded  i^cwu  2qrs.  of  foap.  According  to  the  returns  mentioned  in  a  former  part  of  the 
communication,  the  tallew  and  rofin  alone  ihould  have  afforded  ticwt.  fo  that  the  fifli  ap* 
pears  only  to  add  2cwt»  It  might  be  fuppofed  that  this  icwt.  2qrs.  of  filhy  matter  had  combined 
with  the  tallow  and  alkali,  forming  part  of  the  foap :  it  was  otherwife,  the  greater  part  was  of 
a  black  colour,  and  adhered  to  the  under  part  of  the  foap,  immediately  above  die  wafte  leys. 

Experiment  IL 

Ctvt.  qrs.  lb* 
Herrings  •---800 
Tallow  ----400 

Rofin  -        -        -        -        I      o      o 

Thefe  materials  afforded  lywu  ^qrs.  4/^.  of  foap :  of  this  the  tallow  and  rofin  gives  ^ctuK- 
and  the  fifh  ^£tut.  The  greater  part  of  the  fifhy  matter  was  ulelelsi  being  nearly  in  a  gela- 
tinous ftate. 

Obfirvation. 

Tn  the  art  of  hard  foap  making,  it  is  known,  that  the  addition  of  fea-ialt,  or  weak  kelp  ley,. 
IS  neceflary,  to  enable  the  foapy  compound  to  feparate  and  rife  to  the  top  of  the  wafte  ley. 
If  we  attempt  to  follow  this  pra&ice  with  the  combination  of  fi(h  and  tallow,  inftantly  the 
fifhy  matter  feparates,  and  the  tallow  dies  to  the  top  in  die  form  of  light  yellowilh  coloured 
iwp«    This  h6t  fhows  us  the  impoffibility  of  combining  filh  and  tallow  to  make  hard  ibap. 


Sfiji  Soap  maii  frm  Fijb^  TalktUy  btc. 

Experiment  I. 

lb.     9Z. 

Herrings 

•       .       - 

36      0 

Tallow 

.       •       •       . 

4    " 

Rofin 

.... 

a      Si 

Palm-oil 

.... 

X      aj 

This  gave  45/2.  of  foap  of  the  confiftence  of  treacle.  According  to  calculation,  the  talUbus 
Mfin^and  palm-oil  gives  i8/^.  119%.  and  the  fiih  27A.  The  foap  in  this  ftate  is  too  foft  for 
die  macket,  fb  that  it  requires  to  be  deprived  of  a  portion  of  its  moifhire  to  reduce,  it  to  the 
ftate  of  common  foft  foap,  when  it  weighs  only  33/^.  It  was  found  a  difficult  operation  to 
tfied  an  union  of  the  fifh  and  tallow,  as  it  required,  not  only  a  longer  continuance  of  boiling, 
but  idfo  a  greater  proportion  of  alkali,  than  a  fimple  combination  of  tallow  and  rofin*  Even 
after  careful  boiling,  if  die  alkali  contained  the  finalleft  portim  of  fea-filt,  die  fiih  feparated 
ftom  the  tallow :  this  is  a  circumftance  of  fuch  a  nature,  as  to-  render  working,  in*  the  great  way 
very  precarious. 

Many  other  experiments  of  the  fiune  nature  widi  the  one  now  mentioned,  are  rdbttd  in  the 
leport  ^  but  it  wiU  be  fufficiendy  (atis&Sory,  to  give  the  following  table  of  expences,.  which  is 
Aawn  up  upon  an  average  of  all  die  trials. 

Expenct 


QugUtUs  and  Valui  rf  Fijh  Soap. 


i»5 


Expend  df  manufaffuring  a  Tin  of  Sir  John  DalfjmpVs  Soft  Soap. 


Fiflx 

Tallow 

kofm 

Palm-oil 

Pot-alh 

Lime 


CwU    qrs.    lb, 
i8 

2 


I 

O 

5 
3 


2 
O 
I 

2 

3 


o 

10 

I 
o 

o 
o 


oz. 

o 
o 
o 

3^ 

o 

o 


Value 


c 

s. 

d. 

-    I 

I 

^ 

5 

17 

o 

I 

0 

a 

I 

II 

I 

15 

8 

o 

o 

3 

6 

2 

o 

o 

2 

3 

o 

i6 

6 

8 

3 

o 

Q 

)C-47 

12 

4l 

48 

O 

o 

Expence  of  manufii6luring 
Firkins  as  packages 
Duty      ... 
Profit      -        -        - 


What  the  manufa^rer  can  afFord.  to  fell  a  ton  at 
Common  foft  foap  a  ton         .        .        •        •        - 

From  this  calculation,  we  find  only  a  very  trifling  difference  of  expenee  between  the  dfk 
ibap,  and  common  fi>ft  foap :  and  experience  has  (hewn  mey  that  ictvU  of  commoa  foft  ibap 
is  equally  valuable  with  icwU  ifrs.  of  fi(h  (bap.  This  article,  therefore,  can  never  be  bioi^;ht 
into  the  market. 

Sir  John  Dalrymple  having  found  that  the  methods  propofed  in  die  patent  were  not  likely 
to  be  attended  with  fuccefs,  has  adopted  an  old  pradice  of  the  Swediih  peaCmtry,  in  forming 
ai  foft  foapi  without  oil  or  tallow,  by  dillblving  fifh  in  cauftic  potalh.  In  the  report,  we  have 
a  number  of  trials  upon  this  combination,  with  a  view  to  afcertain  the  expenoe  of  manufcftur* 
ing,  and  the  following  lift  of  expences  is  drawn  up  from  thefe  trials. 

Expence  of  manuf alluring  a  Ton  of  this  Soap ;  and  what  the  ManufaRurer  can  afford  to 

feU  it  at. 


FiOi 
PotaOi 

Lime 


Value 


T.  cwt.  qrs*  W. 

-        -         I     lo 

o      6 

.        .        o      3 

Labour,  fuel,  &ۥ  ......       i 

Firkins  as  packages 

Duty         -        -        - 

Profit        .... 


X. 

o 
i6 

3 

o 

a      3 

i6    i6 


o 

6 

o 
a 
8 
o 


)C-4«    9      a 


From  the  above  flatement  it  would  appear  diat  the  fifh  foap  would  fuperfede  the  nib  of  com« 
mon  foft  foap.  Expaience  however  has  fhewn  me  that  icwt.  of  common  foft  foap  will  clean 
nearly  as  much  linen  as  icwt  of  this  fifliy  combination*  We  muft  therefore  conclude,  that 
Done  of  the  prop<^  mttbods  will  be  in  any  economical  point  of  view  of  much  confequence*' 

Q  2  Having 


m6  QuaSties  end  VMi  •/  Fifli  S^f. 

Having  diufi  ftatcd  tbc  reMts  of  the  cxpcritnents  Isid  before  the  Board  of  Truftees  by  my 
fether,  I  will  conclude  this  paper,  with  fome  mifcellaneous  obfervations  upon  the  combination 
of  fi(b  and  potafh,  and  the  relation  of  a  few  experiments  on  other  faponaccous  compounds. 

When  caufttc  potaih  and  fi{h  are  heated  together^  a  decompofition  of  the  anknal  matter 
foon  commences,  as  is  demonftrated  hy  the  feparation  of  a  quantity  of  ammosua.  The 
quantity  of  ammonia  feparated  or  formed  in  this  procefe  is  fo  great,  that  OxouU  tSie  fifhy 
compound  jNTove  of  any  ufe,  it  would  be  economical  to  colle£l  the  ammoniacal  vapours  in 
a  chamber  with  muriatic  acid  gas,  to  form  muriate  of  ammoniac.  This  ammonia  is  derived 
not  only  from  the  gelatine,  but  alfo  from  the  pure  fibrous  matter,  as  I  found  by  particular 
trials  with  it.  This  fifh  foap  has  a  more  or  lefs  brown  colour,  varies  in  its  confidence^ 
which  depends  on  the  quantity  of  water  it  contains ;  it  has  a  moft  difagretable  fmell,  and 
by  keeping  in  a  damp  place  becomes  fofter,  and  acquires  a  thin  whitifh  covering.  The  bony 
matter  of  die  fifh  is  not  diflblved,  but  remains  fu^nded  in  the  ibap ;  £>  that  when  the 
foap  is  diflblved  in  water,  the  bony  matter  falls  down.  When  an  acid  is  added,  the  Hlhy 
matter  is  feparated  of  a  white  colour,  and  remains  diffufed  through  the  water,  giving  it  a  milky 


r-^  Sir  .John  Dalrymplc  mentiona  in  his  printed  letters,  that  from  repeated  experience,  he 
has  diibovered  this  ibap  to  be  poflefled  of  peculiar  properties,  which  he  hys^  independent  of  its> 
cheapnefs,  will  render  it  an  obje£l  of  great  national  concern.  The  following  experiments  were> 
DPade  to  try  the  trudi  of  Sir  John  Dalrymple's  ftaCements,  as  affi>  to  oUerve  if  diis  compound 
kad  fimilar  properties  with  common  foap. 

.  I.  With  diftilled  water  it  forms  a  brown^ooloured  fblution,  which  being  kept  for  ieven  0^ 
eight  weeks,  did  not  alter  in  its  appearance  or  fmell.    It  alfo  lathered  pretty  well. 

a.  With  foft  water  it  forms  a  brown-colouredjlfolution,  and  lathers  well. 

3.  With  hard  water  it  is  changed  in  the  &me  manner  as  common  foap,  a  part  of  the 
£ipbhaceous  compound  being  decompofed  by  the  earthy  falts,  which  are  generally  to  be 
found  in  fuch  kinds  of  water.  Sir  John  Dalrymple,  however,  aflerts,  that  it  wafhes  equally- 
well  in  cold  bard,  as  in  cold  foft  water,  and  beiides,  that  it  wafhes  widi  equal  advantage 
although  the  water  be  not  heated.  The  experiment  which  has  been  jtifl  mentioned,  fhews 
that  it  does  not  differ  firom  common  foap  when  ufed  with  hard  water-^that  it  wafhes  equally 
well  in  cold  as  in  warm  water,  does  not  require  refutation. 

41  If  this  foap  be  agitated  in  cold  fea  water,  a  part  of  it  is  decompofed  by  the  earthy  felts, 
contained  in  the  water,  and  the  water  acquires  a  milky  appearance.  This  decompofition  is 
jrendered  the  more  evident,  if  the  folution  be  kept  for  fome  time^  for  it  then  acquires  a  moft 
diiagreeable  fmell,  owing  to  the  putrefaction  of  the  animal  matter,  which  had  been  feparated 
l)y  means  of  the  earthy  falts.  Sir  John  Dalrymple  affirms,  that  this  foap  waflies  well  in  cold 
fea  water,  which  he  juftly  obferves,  is  a  difcovery  of  great  importance.  The  milky  appear.- 
ance,  and  imperfeft  Jathering  which  this  ibap  exhibits  when  agitated  with  cold  fibawater^ 
has  probably  led  Sir  John  Dalrymple  to  draw  this  conclufion.  Thefe  appearances,  however,, 
are  no  proof  of  its  poflei&ng  any  greater  deanfiog  power  than  common  foap  with  iait  water. 

Accordingly 


Exptrimem  on  fhi  S$Mpt  tf  Fijh  mni  9/  Tf^ool.  trj 

Accordingly  wj  father  found  that  this  aflertion  of  Sir  John  Dairfrmple)  was  without 
foundation. 

In  the  6th  volume  of  the  tranfa&ions  of  the  London  Society  of  Arts»  mention  is  made  of 
a  foap)  manufactured  in  India,  which  is  faid  to  wafli  with  fta  water.  It  would  be  very  inte- 
refting  to  have  the  truth  of  thiS  afcertained. 

5.  Chaptal,  in  the  21ft  volume  of  the  Annales  de  Chimie,  has  defcribed  a  method  of  making 
fbap  from  wool,  and  he  remarks  towards  the  conclufion  of  his  paper  *'  This  foap  has  been 
employed  in  every  mSinner,  and  under  every  form,  in  my  manufaftory  for  dying  cottons ; 
and  I  am  at  prefent  convinced  that  it  may  be  fubftituted  inftead  of  the  faponaceous  liquor 
we  make  from  lixivium  of  foda  and  oil,  to  prepare  the  cottons.  I  have  conftantly  obferved^ 
that  by  diffolving  a  fufficient  quantity  of  this  foap  in  cold  water  to  render  the  fluid  milk^^  '"--  ■ 
fcnd  by  working  the  cotton  with  the  apparatus,  which  is  well  known,  it  is  fufficient  to  pafs  the 
cotton  three  times  through,  drying  it  each  time,  in  order  that  it  may  be  as  well  difpofed  to 
receive  the  dye,  as  that  which  has  been  pafled  feven  times  through  the  ordinary  folution  of  ;  '^■.■. 
(osip*    This  will  not  appear  fiirpriflng,  when  it  is  conddered  that  animal  matters  are   very  -J 

proper  to  difpofe  thread  and  cotton  to  receive  the  dye,  and  fome  of  the  operations  of  our  dye 
pfcxks  confift  Amply  in  impregnating  them  with  thefe  fubftancts  */'  In  feveral  trials  which  I 
have  made  with  this  fifh  foap,  I  find  that  it  gives  a  greyilh  or  brownifh  tinge  to  cotton  clodi^ 
:wbich  remains  after  repeated  wafhing  with  common  foft  fbap*  If  this  be  found  to  hold  true 
an  other  trials,  it  is  not  improbable  that  this  fiih  foap  may  be  ufed  in  place  of  wool  foap^ 
jn  the  proceflbs  mentioned  by  Chaptal.  Several  preliminary  trials  muft  be  made^  to  determine 
whether  the  Gallic  acid  decompofes  this  compound,  and  if  the  aftringent  principle  will  combine 
with  the  fifhy  matter ;  at  leaft,  this  is  neceflary  in  the  procefs  for  dying  cotton  red*  (Sep 
Chaptal's  paper,  Annales  de  Chimie,  vol.  26th.) 

ff^ool  Soap  with  Tallow^ 

Having  obferved  from  the  preceding  experiments,  that  the  mufcular  fibre  of  fi(h  does  not 
unite  with  tallow  in  making  hardfoap^  I  imagined  that  other  animal  &ibftances  might  polTefs 
the  (ame.  property.  Accordingly  I  made  feveral  experiments,  with  the  view  of  uniting  the 
woolly  matter  with  tallow. 

Experiment  i.  A  quantity  of  vAAte  woollen  doth  was  diflblved  in  cauftic  potafli,  ^a  a 
confiderable  portion  of  tallow  was  added,  and  the  wbde  boiled  (with  a  frefli  addition  of  ley) 
until  a  brownifh' coloured  foap  was  formed.^ 

2.  A  quantity  of  wool  fixq>  which  had  beeamade  about  a  year  before,  and  flill  retsuiied.a 
di&greeable  imell,  was  boiled  with  tallow,  and  formed  a  foap. 

3*  A  quantity  of  wool  (bap  was  boiled  with  whale  oil,  and  aflfbrded  a  (oap» 

4.,  A  quantity  of  foap  made  with  wool  and  tallow  was  boiled  with  water;  fea  iait  was 
then  added)  and  the  boiling  coAtimiedibr  fome  time ;  the  tallow  foon  leparattd)  and  rofe  to  th^ 

^  FhiloC  Journal^  L  4^«> 


iiS  Soaps  tf  #W,  of  Ghu^  4f  Peatj  (fc. 

top,  m  the  form  of  white  foap  :  below  in  the  wafte  ley  was  the  brown-coloured  woolly  matter: 
This  experiment  fliews  the  impolEbility  of  combinlnywoolly  matter  and  tallow  to  form  hard 
foap.     I  next  endeavoured  to  combine  glue  with  tallow»  and  to  form  a  hard  foap. 

Glue  Soap. 

I  took  a  quantity  of  common  joiner's  glue,  and  boiled  it  with  cauftic  potafli,  until  it  was 
diflblved;  during  the>  boiling, a  condderable  quantity  of  ammonia  was  feparated,  which  gave 
the  combination  a  pret^  dai^k  colour.  This  compound  was  again  boiled  with  a  firefli  portion 
of  cauftic  potafliy  along  with  a  quantity  of  tallow ;  and  the  boiling  was  continued  untOy 
upon  cooling,  a  fine  yellow-coloured  foft  foap  was  formed.  This  foap  had  a  very  ftrong  fmell9 
fomewhat  like  putrefying  fifb.  When  it  was  boiled  with  fea  ^It,  to  form  a  hard  foap,  a 
dccompofition  was  immediately  eflFeded  i  the  tallow  rofe  to  the  top,  in  the  form  of  white  foapi 
and  1}elow  in  the  wafte  ley  was  the  glue  of  a  brown  colour  and  curdled. 

Peat  Soap. 

Having  found  from  the  preceding  trialsy  that  neither  the  mufcular  fibre,  g|lue,  or  wool, 
would  remain  united  with  tallow  in  the  common  procefs  of  hard  foap  making  ;  it  occurred 
to  me,  that  different  vegetable  fubftances  might  be  ufefuL  Accordingly  I  endeavoured  t» 
combine  peat  and  tallow  together,  fo  as  to  form  a  hard  foap.  I  diflblved  a  quantity  of  peat 
in  caufljc  potafli,  and  continued  the  boiling  until  the  compound  had  acquired  the  confiftence 
of  common  foft  foap.  In  this  ftate  it  was  fiduble  in  water,  and  lathered  with  it  With  tallow 
it  formed  a  brown-coloured  foap,  which  was  not  decompo(ed  by  boiling  with  fea  (alt.  I  was 
in  hopeS9  from  this  circumftance»  that  it  might  enable  us  to  introduce  an  ufeful  manufadury 
into  the  Highlands  of  Scotland,  where  peat  is  to  be  got  in  great  quantity.  I  found,  however, 
that  it  gave  a  brown  colour  to  cloth  which  was  wafhed  widi  it,  fo  that  my  attempt  at  rendering 
it  uieful  was  fruftrated. 

Prefervathn  of  Axumal  Subftanas  by  Atkaline  Solution. 

Sir  John  Dalrymple,  in  his  examination  before  the  Houfe  of  Commons,  claimed,  as  a 
dtfcovery  of  the  greateft  importance,  the  method  of  preferving  fifti  by  immerftng  them  in 
a  folution  of  alkali.  This  is  fomewhat  furprifing,  for  we  find  this  hdt  mentioned  long  ago, 
and  in  diiFerent  publications.  Thus,  in  one  of  the  early  volumes  of  the  Trania&ions  of  die 
Royal  Society  of  London,  feveral  experiments  are  related,  on  die  power  of  lime  water  in 
preferving  animal  fubftances,  and  it  is  remarked,  that  fifh  immerfed  in  lime  water,  were 
preferved  firefli  for  a  cenfiderable  time,  ^tr  John  Pringle  alfo  made  feveral  experiments 
on  the  antifepdc  power  of  cauftic  alkalies ;  and  more  lately,  in  one  of  the  volumes  of  die 
Traii£iiftions  of  the  Royal  Irilh  Academy,  there  are  feries  of  experiments  on  the  andieptic 
power  of  cauftic  sdkalies. 

Sbirif  Bree,  Leitk,  KjOBERT  JAMESON,  F.L.S.  a^c. 

May  lUb^  1799. 


Oh  the  Oxfgmfi^fii  U  hi  CifUaioHl  in  Snow,  219 

IV. 

Experiments  and  Obfervations  to  prove  that  Snow  Joes  not  contain  Oxygen^  either  in  Solution 
9T  in  Comhination-t  and  that  its  fertilizing  Quality  does  not  depend  on  this  Caufe.  By  Dx* 
JOACHIN  CaRRALQRI  DE  PrATO*. 


T, 


HE  generally*received  opinion,  that  fnow  produces  fertility)  is  true,  becaufe  Tt  is  proved 
by  experience ;  but  I  do  not  think  it  can  be  admitted  in  the  fenfe  which  is  commonly  received. 
I  am  well  convinced  that  (how  produces  this  efFefl,  but  I  conceive,  as  many  others  have  aUb 
done,  that  it  ads  in  a  negative  manner  only,  by  defending  the  plants  in  winter  from  a  degree 
of  cold  below  that  of  freezing,  and  not,  as  is  commonly  thought,  from  its  imparting  any  principle 
of  fertility.  But  Citizen  HalTenfratz  at  prefent  thinks  he  has  confirmed  this  laft  opinion,  by 
a  difcovery  of  the  caufe  of  the  phenomenon,  which  he  thinks  muft  be  afcribed  to  a  quantity  of 
oxygen  in  combination  in  the  fnow,  which  it  afterwards  communicates  to  the  (eeds  which  are 
developed  when  it  is  converted  into  water,  and  he  undertakes  to  prove  by  feveral  experiments^ 
that  fnow  water  contains  much  oxygen  in  the  ftate  of  combination  f  • 

I  ihall  prove  by  inconteftable  fads,  that  fnow  water  does  not  contain  pure  oxygen  in  the 
fiate  of  (blution  or  aggregate,  nor  in  the  date  of  fixity  or  combination  ;  and  confequently  that 
the  fiiow  cannot  impart  fertility  by  virtue  of  this  principle. 

In  the  month  of  Auguft  of  the  prefent  year,  I  took  the  pureft  fnow  I  could  find,  and  after 
having  wafhed  it,  I  filled  a  fmall  glafs  bottle  with  a  long  neck,  and  when  it  began  to  diflblve, 
I  covered  it  with  very  pure  oil  olive,  in  order  that  it  might  not  abforb  any  air  from  the  atmofphere. 
About  fixteen  hours  afterwards,  1  firfl  removed  the  whole  of  the  oil  from  its  furfiice,  then  threw 
in  a  finall  fifh,  and  immediately  afterwards  covered  the  water  with  frefh  oil.  When  the  fi(h 
entered  the  water  it  began  to  druggie,  and  died  almeft  infbntly.  I  threw  in  another  with 
the  fame  precautions,  and  it  alfo  died.  Laftly,  I  took  a  portion  of  water  of  the  fame  fnow^, 
which  had  been  kept  for  the  fame  time  expofed  to  the  air,  in  a  receiver  with  a  large  mouth, 
and  poured  it  into  a  fmall  glafs  bottle  equaT  to  the  former.  Into  this  I  threw  a^  fifh  of  the 
fame  fize  as  before,  and  immediately  covered  the  water  with  oil  olive;  but  in  this  water 
the  fiib  gave  no  figns  of  uneafinefs,  and  lived  quietly  for  more  than  three  quarters  of  an 
hour.  The  thermometer  flood  at  nineteen  degrees  of  Reaumur  during  thefe  experiments,  and 
the  barometer  at  about  27  inches  and  a  half. 

As  I  have  elfewhere  proved  %  that  fifh  by  their  refpiration  in  water,  have  the  facuk}'  of 
abforbing  all  the  oxygen  it  contains,  and  diat  they  immediately  die  in  water  which  Js  entirely 
deprived  of  oxygen :  I  inferred  from,  thefe  experiments,  that  fhow^  water  does  not  contain 
oxygen  in  a  ftate  of  folution. 

*  Journal  dc  Phyfique^V.  126. 

f  Journal  Politechnique,  IV.  Cahter;  of  which  Ibme  account  it  givtn  in  our  Jounial,  L  144.. 

X  Annakt  de  Chimici.  ct  Hift.  Nat.  de  Pavie,  tooie  5  et  14, 

III: 


»M  Suppufiit  Okygm  in  Snon 

In  order  to  confirm  my  dcduftion,  I  immediately  poured  the  water,  in  which  the  fiflies  had 
died%  into  a  receiver,  which  prcfented  a  large  furface  to  the  air,  and,  a  few  inflants  afterwards, 
I  threw  in  a  fifli  of  the  fame  fpecies,  which  lived  very  well  in  it,  and  might  have  remained  as 
long  as  I  chofe.  It  is,  then,  an  inconteftable  truth,  that  the  mere  want  of  oxygen  was  the 
caufe  of  the  death  of  the  two  fifli  thrown  into  the  fnow  water  in  the  firft  experiment ;  for  it 
is  very  evident,  that  when  the  (how  water  was  placed  in  a  fituation  to  re-abforb  the  oxygen,  of 
which  it  had  been  deprived  by  its  congelation,  it  became  as  capable  of  maintaining  the  life 
of  fiflies  as  any  other  water. 

But  it  feems  certain,  from  feveral  experiments,  that  fnow  water  rc-abforbs  oxygen  from  tha 
atmofphere  more  flowly  than  other  waters  which  were  deprived  of  it.  I  have  before  remarked, 
that  fnow  water  after  having  been  expofed  during  fixteen  hours  to  the  air,  contained  fo  litrfc 
oxygen,  that  it  could  fcarccly  fupport  the  refpiration  of  afmall  filh  for  an  hour ;  whereas  I  knew 
from  other  trials^  that  waters  commonly  contain  a  fufficient  quantity  of  oxygen  for  the  refpira- 
tion of  a  fma-l  fifli  in  the  fame  circumftances  for  feveral  hours.  It  feems  proper,  therefore, 
to  conclude,  that  the  water  by  its  converfion  into  fnowlofes  part  of  its  difpofition  to'abforb 
tiie  oxygen  of  the  atmofphere.  But  in  order  to  determine  this  more  accurately,  I  chofe  to 
make  fome  trials. 

I  exhaufted  all  the  oxygen  contained  in  two  pounds  of  well  water,  by  the  refpiration  of  a 
iifli  which  was  kept  in  the  water  included  in  a  narrow-necked  bottle  until  it  died.  When  the 
fifli  was  dead,  i  cleared  the  bottle  very  exadly  of  the  whole  of  the  oil,  and  poured  the  water 
into  a  veflel  with  a  large  aperture,  in  which  I  kept  it  expofed  to  the  air  for  fixteen  hours.  I  then 
returned  the  water  into  the  fame  bottle,  introduced  a  fifli  of  die  fame  fize  and  kind,  and 
immediately  covered  it  with  oil.  At  the  end  of  four  hours  the  fifli  was  flill  alive,  but,  after 
half  an  hour  longer,  it  died  in  convulfions,  in  the  fame  manner  as  fiflies  ordinarily  die  for  want 
of  air.  Well  water,  therefore,  though  totally  deprived  of  oxygen  like  fnow  water,  that  is  to 
(ay,  to  the  point  of  being  incapable  of  maintaining  the  refpiration  of  filhes  during  the  fame 
time,  did  rc-abforb  more  oxygen  than  fnow  water. 

This  cannot  be  attributed  to  the  quantity  of  foreign  matters  ufiially  contained  in  fnow  water, 
on  the  fuppofition  that  they  either  hinder  the  water  from  re-abforbing  oxygen,  or  the  fifli  from 
extra&ing  it  by  refpiration ;  fur  I  have  found  that  fiflies  live  for  feveral  hours  in  turbid  water 
expofed  to  the  fame  circumftances  as  the  fnow  water :  and  I  have  alfo  proved  that  tfais*  water, 
after  having  been  deprived  of  oxygen,  re-abforbs  it  in  Icfs  time  than  (how  water. 

Neverthelefs,  fnow  water,  after  a  long*interval  of  time,  becomes  again  charged  with  all  the 
oxygen  it  .can  contain,  and  becomes  capable  of  maintaining  the  refpiration  of  fifli,  like 
every  other  water.  In  the  month  of  September,  I  kept  clear  fnow  water  for  five  days  in  a 
bottle ;  and  in  order  that  the  oxygen  might  infinuate  itfelf  more  eafily,  I  firft  filtered  it  through 
a  paper,  and  afterwards  agitated  it  every  day  in  the  receiver.  This  water  (b  treated,  abforbed 
as  much  [oxygen  as  it  was  capable  of  holding ;  for  when  it  was  introduced  into  a  fmall  bottle 
with  a  narrow  neck^  it  fupported  the  life  of  a  fi(h  for  Aine  bours^  which  was  introduced  and  the 
the  wate   covered  with  oil. 

'But 


But  fnow  wAter  docs  not  even  coojUio oxygen  in  a  combined  (latsci  a^  Uallenfratz  pretends. 

I  have  proved  this  by  thp  oioft  decided  eKpeciments.    If  melted. fnow  be  oxygenated  watOTt 

Containing  oxygen  in  the  ftate  of  :coinbination)  it  will  foliow  that  when  expofed  to  the  fu.i 

tt  ^ill  emit  the  Oxygen  iagain  in  the  ,ga(ceous  forni,  by  the  combination  of  caloric  and  light, 

precifely  in  the  fame  manner  as  it  eicapes  and  (hews  itfelf  when  the  nitric  or  oxygenated 

muriatic  acids  are  expofed  to  the  fi>l^  light.      But  certainly  fince  fnow  water  does  not  con* 

tain  oxygen  in  folution,  but  can  abforb  it  fucceifively  as  often  as  it  is  expofed  to  the  atn(i9- 

fphere,  it  muft  at  leaft,  if  this  .principle  do  exift  in  (how,  contain  it  in  the  aggregate  ft^^. 

1  therefere,  in  the  month  of  September,  jn.^  .prefent  year,  put  very  pure  fnow  in  (mall 

pieces  into  a  fmall  glafs  bottle  with  a  narrow  neck,  and  before  it  was  entirely  melted^, I 

poured  oil  upon  its  furface,  in  order  4P;ptievent  the  co^ioiunication  ^Ith  the  ajTi  and  after* 

wards  expo(ed  it  /or  three  fucce(Sve  days  to  liifi.  TMn ;  fo  that  the  whole  tiiac  of  expoAupe 

amounted  to  eighteen  hours  s  and  afti?rward%  having  well  cleared  it  of  the  oil,  I  introduced 

a  fmall  fifh  :  it  died  inftantly,  as  in  the  fnow  water  immediately  after  liquefaAion.  An$l  nojt* 

Withftanding  the  loi\g  eXpoTure  tp  the  fun>  whicb  i^endered  it  very  perceptibly  warm,  though  I 

obferved  it  witji  every  po(&ble  Attention,  J  never  perceive^  the  fqfialleft  bubble  ^  indicati^ 

of  oxygen*    Confeq^ent^  it  cannot  be  Admitted  that  this  water  was  charged  with  oxygqn 

in  combination,  becau(e  it  mud  .have  ^fn^aped  in  the  fprqi  of  gas  ;  and  if  it  .had  afterwards 

abforbed  it,  the  fi(h,  which  is  the  fureft  indication  of  the  fmalleft  quantity  of  oxygen  in  water^ 

"would  have  availed  itfelf  of  it,  and  lived  for  fi>me  time. 

The  experiments  of  Ha(renfrats,  which  -fisem  to  prove  by  analyfis  the  prefence  of  com^ 
bined  oxygen  in  (iiow  water^  are  not,  in  my  apprehenfipn,  conclufive,  becaufe  they  are  not 
confirmed  by  fynthdls.  It  is  not  an  exclufive  property  of  water  (aturated  with  pure  oxygen 
in  a  combined  (bte  to  alter  the  tin£lure  of  turnfol  to  a  red  colour,  and  to  precipitate  the  (o^i- 
tion  of  fulphate  of  iron. 

It  has  already  been  obferved  by  Bergman,  in  his  analyfis  of  waters,  that  fnow  recently  lique* 
fied  is  abfolutely  without  air ;  but  his  afTertion  is  not  well  proved,  becaufe  the  method  he  made 
ufe  of  to  afcertain  the  exiftence  of  vital  air,  or  oxygen  in  water,  namely,  boiling,  is  abfolutely 
imperfeft.  Water  retains  its  oxygen  too  ftrongly,  to  allow  its  being  cxtraSed  by  boiling,  as 
this  experiment  Would  require.  I  filled  a  fmall  matrafs  with  well  water,  and  boiled  it  for  an 
hotil*  and  a  half,  and  upon  taking  it  from  the  fire,  I  poured  it  out  beneath  oil,  in  order  that  no 
air  might  enter.  When  it  was  cold,  I  took  off  the  oil  and  put  in  a  fi(h,  immediately  after 
which  I  covered  it  again  with  oil-olive.  Notwithftahding  the  boiling,  the  fifh  found  a  fuf- 
ficient.  quantity  of  oxygen  in  this  water  .to  enable  him  to  live  more  than  three  hours. 

Frcfh  water  fifh  are  true  eudiometers  for  water,  for  when  they  refpire,  they  have  the  faculty 
.of  abforbing  all  the  ox;ygen  jt  contains.  From  this  property,  natural  philofophers  may 
have  recourfe  to  them  for  meafuring  the  quantity  of  oxygen  contained  in  different 
waters,  by  taking  fifh  of  the  fame  fpecies  and  fize,  and  obferving  the  time  they  live  in  equal 
quantities  of  die  water.  In  this  way  a  feries  of  experiments  might  be  inflituted,  to  deter- 
ntine  the  tnie  proportions  of  oxygen  contained  in  different  waters ;  as  has  been  done  byFontana, 
though  by  tbe  uncertain  method  of  boiling.     But  it  will  be  necefTary  .to  take  into  confiden* 

VoL  III— June  1799*  R  tion 


1st  Snnt^^-'On  Strontian  and  Baryteu 

tion  the  rariations  of  Ae^1>aroineter  and  thennometery  becaufe  I  have  obfenred  dnfc 
contains  lefi  oxygen  in  fummer  than  in  winter ;  and  when  the  borooiettr  is  high  (qiu  low  ?) 
dian  when  low^  the  reaibn  of  which  is  fufficiently  evident. 

Bergman  affirms^  t)>at  fiiow  affords  an  indication  of  nitrous  acid.  If  this  \t  true,  it  ac« 
counts  for  its  efFeA  in  burning  ieatheri  and  other  fubftances  plunged  therein  %  as  Haflenfratz 
has  remarked,  who  afcribes  it  to  the  combined  oxygen,  with  which  be  thinks  it  is  fiiturated. 
Is  it  probable  that  this  acid  fhould  be  fDrmed  at  the  moment  of  the  congelation  of  the  water, 
by  the  concentration  or  mechanical  approach  of  die  parts,  caufed  by  the  cold  in  die  oxygen 
gas,  with  which  the  water  is  charged,  and  the  azodc  gas  which  may  be  afForded  by  die  a(-^ 
mo(phere  ? 

Let  this  be  as  it  may,  a  queftion  will  prelent  itfelf  concerning  diis  commoidy  fiippofed  ac- 
tivity of  fiiow,  namely,  how  it  can,  if  reduced  according  to  the  afierdon  of  Haflenfratz,  into 
water  pofleffing  the  fiune  qualities,  prove  beneficial  for  developing  the  tender  embrios  of 
vegetables  ? 

It  feems,  therefore,  that  from  the  whole  confideratioR  of  the  fobjiefk,  we  are  jtsftified  in 
concluding,  that  there  is  no  reafon  to  believe  that  (how  communicates  any  pofidve  fertility  to^ 
die  earth ;  its  good  efFeds  muft  be  attributed  merely  to  the  fimple  prefervadoiv  of  [daots  from 
intenfe  cold,  which,  by  altering  dieir  orgamsation>  would  deftroy  die  powers  of  lifo« 


v: 

On  certain  PropirtJes  ef  Strantian  and  Barjtis.    Bj  Citizen  Vav^^ELIN^ 


s 


INCE  the  method  of  obtaining  barytes  and  ftrondan  In  a  ftate  of  perfefl  purity  has  beeii 
difcovered  by  chemifts,  they  have  obferved  ieveral  properdes  in  thefe  earths,  analogous  to. 
thofo  of  the  alkalis,  fuch  as  the  acrid  burning  tafte,  fdubility  in  water,  and  feparadon  in  cfyf-* 
ta]s>  together  with  the  change  which  they  produce  in  the  blue  colours  of  vegetables,  which 
they  convert  into  green* 

I  ihall,  on  the  prefent  occafion^  exhibit  fome  other  of  their  properties,  which  I  apprehen4 
may  ferve  to  (hew  their  ftill  more  ftriking  refemblance  to  the  alkaline  fubftances. 

About  a  year  and  a  half  agp,  upon  analyzing  a  filiceous  fulphate  of  barytes,  I  found,  afttc 
having  decompo(i»l  it  with  charcoal,  that  the  greateft  part  of  die  filex  had  been  diflblved  bgr 
die  acid  I  made  ufe  of  to  decompofe  the  fulphate  which  had.  been  formed* 

I  could  not  immediately  determine  the  caufc  of  this  unexpefted  event,,  but  merely  fuppofcdi 
die  barytes  to  have  produced  it 

I  have  fince  made  (bme  more  dired  experiment^  to  elucidate  this  queftioni,  there(LiltQ£ 
which  ihews  that  my  fuppoGdoa  was  not  without  foundation. 

Experinunts  on.  Strontioiu 

Experiment  X.  Two  hundred  parts  of  ftrontian  in  fine  powder,  mixed  widi  fixty-  parts^ 
4sf  filex  alfo  powdered,  were  fiibje^ed.  for  an  hour  to  a  ftrong  fire.ia a  crucible  of  pladns^; 

the: 


Co/niinaiicHi  0/ SifMtian  with  Slhx  ani  AlumnB.  tag 

IIm  ^Utidud  vras  1  grey  fonorous  mafs,  cracked  in  various  places,  the  p^Mtsjof  which  adhered 
together  with  confiderable  force.  In  this  ftate,  it  had  no  very  evident  tafte,  but  when  pulve» 
rized  it  was  flighdy  cauftic  (  when  put  into  .water,  whether  in  the  lump.or  in  powder,  this 
compound  neither  produced  heat  nor  fwelled  up,  as  is  the  cafe  with  the  pure  ftiontian.'  It  only 
became  fomewhat  whiter. 

Experiment  2.  The  fubftance  laft  fpoken  of  was  pulverized  and  boiled  in  water,  whidi 
diflblved  it  much  lels  abundantly  than  pure  ftrontian,  but  the  water  acquired  a  flight  alkaline 
tafte,  and  foon  became  covered  with  a  white  pellicle :  it  did  not  afford  cryftals.  When  (atn- 
cated  with  nitric  acid,  this  folution  afforded,  by  evaporation,  a  jelly  in  confiderable  abundance. 

Experiment  3.  Another  portion  of  the  fame  matter  pulverized  and  moiftend  with  a 
little  water,  was  totidly  diflbl ved,  by  the  muriatic  acid,  and  the  folution  afforded  by  evapora-* 
tson  a  very  abundant  jelly,  which,  after  walking  and  drying,  prefented  all  the .  chara&ers  of 
filex.    The  nitric  and  acetous  acids  produced  the  (ame  eiFe^  on  this  fubftance. 

Experiment  4.  Five  parts  of  pure  ftrontian  in  fine  powder,  and  one  part  of  alumine,  re- 
oendy  prepared,  and  ftill  humid,  vftvt  heated  together  with  water,  and  when  die  liquor  had 
fully  boiled,  it  was  filtered,  and  contained  much  undiflblved  matter.  The  filtered  liquor  had  a 
flight  alkafine  tafte,  but  did  not  cryftalize,  though  a  much  greater  quantity  of  the  earth  had 
been  ufed,  than  could  be  diflblved  without  heat. 

This  folution  was  then  iaturated  with  muriatic  acid,  and  being  afterwards  mixed  with 
ammoniac,  affo^died  a  fmall  quantity  of  flocculent  matter,  which  was  alumine. 

Strontian  confequendy  poftefles  the  property  of  favouring  the  foludon  of  alumine  in  water ; 
but  what  is  more  remarkable  is,  'that  the  alumine,  on  die  other  hand,  rendered  a  great  quantity 
of  the  ftrontian  inlbluble ;  for  the  water  did  not,  in  this  cafe,  diflblve  one-tenth  part  of  v^C 
k  would  elfe  have  taken  up. 

The  examination  of  what  remained  on  dye  filter,  proved  that  the  ftrontian  became  infiilublcf 
by  an  intimate  combination  between  thefe  two  earths ;  and  it  is  probable,  that  if  a  greater 
quantity  of  alumine  had  been  prelent,  there  would  not  have  been  a  particle  of  mere  ftrontian 
diflblved. 

The  refidue  was,  in  hSt^  fduble  in  acids,  with  fcarcely  any  effervefcence ;  its  folution  a& 
forded  a  flocculent  precipitate  of  alumine,  by  means  of  ammoniac ;  and  the  fupematant  liquor 
ibrmed  a  very  abundant  depofition,  when  carbonate  of  potafti  was  added. 

It  will  not)  therefore,  be  furprifing,  if  a  combination  of  thefe  two  earths  fI\ould,  hereafter, 
be  found  in  nature* 

Cnuiming  Burytes. 

Experinunt  i  •  One  hundred  and  fifty  parts  of  cauftic  barytes  were  mixed,  as  accurately  as  pof. 
fible^  wtdi  fifty  parts  of  filex,  and  the  whole  was  aftervi^s  ftrongly  heated  for  an  hour  and  a 
half  in  a  crucible  of  platina.  The  mafi  was  in  one  fingle  piece,  cracked  in  various  places,  but 
mdioutdie  cdiefion  obferved  in  the  e3q)erinient  widi  ftrontian.  Its  cdour  was  a  light  apple 
green,  its  tafle  almoft  mild,  and  it  did  not  heat  with  water,  whether  it  was  immerftd  in  lumps, 
pr  in  powder.    It  Qreferved  its  green  colour  in  die  water. 

R  2  Experiment 


ttjf  GmAhmihiu  if  SaryUf  voifh  Sihx  amtJkmtiie. 

Bxferimini  a.  The  pure  nitric,  muriatic,  and  aCetckis  acids  totally  difibktf  this  febftoncel 
Its  iblutiony  in  any  one  of  thefe  acids,  immediately  affords  a  fiocculent  precipitate  by  ammdniac^ 
Thefe  fdutions  become  gelatinous  by  evaporation^  and  when  compkteiy  dried,  the  filex  ft 
again  developed  in  poffi^ffion  of  all  its  propertied  It  cannot,  therefore,  be  doubted,  but  that 
barytes,  as  well  as  ftrontian,  poflefles  the  property  of  combining  with  filex,  and  06  renderihl^ 
it'  foluble,  even  in  the  woakeif  acidl. 

Experiment  3.  Nine  parts  of  4Auftic  barytes  were  mixed  with  one  jSart  of  alumine,  new}y 
feparated  from  its  ibivent,  and  ftill  moift  f  and  the  Whole  was  fubjeded  for  a  quarter  of  an- 
hoor  to  ebullition,  with  a  fufficient  quantity  of  waiter.  Much  undiflblved  matter  femained^ 
The  filtered  liquor  had  a  (lightly  cauftic  tafte,  radiet  ftro/iger  than  that  of  ftrohtian  treated 
in  the  fame  manner.  It  (bon  becaihe  covered  witii  it  white  cruft  by  the  abforption  of  carbonic 
acid  from  die  atmolphere  1  but  it  did  not  cryftalice,-  though  the  qiiantit]^  of  water  was  not 
fufficient  to  have  pfeverrted  that  eflfe£l,  if  die  alumtrie  had  not  been  prefent. 
'  A  drop  of  mufiatic  acid  poured  into  a  glals  of  tiiis  (blution,  produced  a  flocculent  cloudy 
il^hich  was  rediflblved  by  agitation;  A  iecond  and  third  drop  produced  the  fame  effeft,  until 
the  greateft  part  of  the  barytes  was  Saturated ;  but  at  lengtii  the  precipitate  bdng  no*longer 
diflS>lved  by  tiie  motion  imprefled  on  the  fluid,  an  excefs  of  acid  diflblved  it.  When  the 
fluid  was  entirely  (aturated  with  acid,  the  floccuknt  m^ter  was  again  reproduced  by  ammoniac  | 
and  when  this  laft  addition  ceafed  to  produce  any  tfkStf  a  very  abundant  precipitate  was  af« 
forded  by  the  carbonate  of  potaih. 

We  (ttf  therefore,  that  barytes,  as  well  as  fti'ontbui,  diflblves  ahmtme,  and  even  ttrore  abund- 
sftitly  i  heverthelefr,  there  ftitl  remained  in  die  refidue  a  ^rtion  of  alumine  and  barytes^ 
#hich  were  not  difiblved>  and  appeared  to  be  in  a  ftate  of  intimate  combination. 

SufpeAing  that  this  more  abundant  folution  of  alumine  by  barytes,  dianby  ftrontian,  might 
be  owing  to  a  greater  quantity  of  barytes  having  been  ufed  in  this  experiment  dian  of  ftjt)n- 
tian  in  die  other ;  I  made  a  fecond,  in  which  I  mixed  equal  parts  of  barytes  ai£d  alumine,-  ahdi 
boifed  them  as  before.  The  liquor  ftill  gave  fign*  of  an  abuttdint  iidtition  of  aliithine  a/ii 
barytes,  and  about  half  the  matter  remained  in  the  form  of  a  white  powder  infoluble  in  water; 
in  vrtiich  the  acids  demonftrated  die  prefehce  of  thefe  tv^  eai^s  iitCdfnbinatidn*  * 

The  &me  effefls  take  place  between  ftrontian  and  alumina,  and  ft  is  not  fifrprifing  th^ 
diis  property  extends  rtielf  to  die  alkalis ;  for  when  alumine  15  precipitated  by  pOtafli,  andli 
rather  too  much  of  diis  fubftance  is  added,  die  earth  dways  retaiits  fbnu;  traces  «f  the  alkidi,, 
however  carefully  it  may  be  waflied.  Befides  which,  we  have  examples '  enough  of  glalff 
which  becomes  foluble,  or  infoluble,  accoi'ding  to.  the  quantity  of  alkali;  and  a  ftill  more 
ftriking  inftance  is  afforded  of  potafti  in  hard  flones,^  which,  ouinpt  bi^  Icpin^  by  any  me-^ 
chaiiical  means.. 

The  truth  of  what  is  here  advanced,  may  be  very  iimpl/  fliewft^  by  pMti)9g  %  feuirated 
hot  folution  of  barytes  into  a  folution  of  the  muriate  of  alumine.  A  precipitate  in  Adtes  will 
firft  be  found,  which  will  be  rediflblved  by  anew  quantity  of  the  folution  of  barytes;  and  if 
before  this  precipitate  be  entirely  rediflblved,  it  be  feparated  from  the  fluid^.  it  will  be  found 
to  be.  comfiofed  o£  alumine  and  barytes.. 

Jffarjtes 


Barytes  and  OIL 


if5 


'^^^xpirlnunt  4.  It  is  known  that  when  a  folution  of  barytes  or  ftrontian  is  poured  Into  a  ibiu- 
tion  of^  common  foap,  a  very  abundant  depofition  is  formed,  which  is  a  coipbination  of  the 
earth  witn  the  oil  of  the  foap,  while  the  alkali  remains  pure  andcauftic  in  the  fluid.  In  order  . 
to  afccrtain  whether  thefe  earths  could  unite  directly  with  oil)  I  boiled  a  folution  of  baryteSy 
made  with  heat,  together  with  oil  olive ;  the  oil  foon  became  confiftent,  the  water  loft  its  alka^ 
line  tafte,  and  the  new  combination  exhibited  the  tafte  and  fmell  of  a  true  (bap,  from  which, it 

differed  merely  in  its  want  of  folubility  in  water. 

'  "•  . 

Barytes  and  Jnimal  Matter* 

Experiment  5. 1  was  deiirous  of  knowing  whether  barytes  would  ad  upon  animal  mattersi  ui 
the  fame  manner  as  the  alkalies,  which  laft  are  known  to  decompofe  them,  and  form  a  kind  of 
foap,  while  ammoniac  is  difengaged.  I  therefore  mixed  twenty  drams  of  bullocks'  liver  pounded 
with  ten  drams  of  barytes  diffufed  in  water,  and  boiled  die  whole  in  a  retort,  to  which  are^- 
ceiver  was  applied.     In  a  very  fhort  time,  I  obtained  a  large  quantity  of  ammoniac,  and  the* 
animal  fubftance  was  converted  into  a  fort  of  clotted  magma  of  a  rofe  colour,  infohible  m 
water,  and  which,  by  feveral  experiments,  I  afcertained  to  be  a  CQmbinatibn  of  fatty  matter  and  • 
barytes.     It  is,  therefore,  proved  that  the  alkaline  earths  exert  the  fame  affion  as  die  alkaliet 
upon  animal  matters,  though  with  a  flight  difference  in  the  refult* 

Cenclujion. 

It  is  evident  from  the  preceding  fads,  i/That  ftrondan  and  barytes  pefTefs  nearly  the  fame 
habitudes  as  the  alkalies,  with  regard  to  filex  and  alumine,  like  which  fubflances  they  con)- ' 
bine  with  the  earths,  and  divide  them  in  fuch  manner,  as  to  render  them  afterwards  foluble  in 
the  weakeft  acids.  2.  That  they  may  be  ufed  like  the  alkalies,  in  the  analyfis  of  hard  flones,' 
which  are  not  attacked  by  acids  ;  a  property  which  maybe  advantageoufly  applied  in  fuch  cafes 
as  do  not  allow  the  exhibition  of  alkalies.  3.  That  it  is  neceflary  to  be  cardful  indecompofing 
the  nitrates  of  barytes  and  ftrondan  in  crucibles  of  earth,  in  order  to  obtain  thofe  bafes  in  a 
Kate  of  purity,  not  to  apply  top  ftrong  a  heat,  forbear  they  fbould  combine  with  iilex  and 
alumine*  4.  That  it  wa^,  no  doubt,  owing  to  combination  with  the  eardi  of  the  crucibles^ 
that  barytes  was  formerly  obtained  in  the  ftate  of  a  frit  infoluble  in  water,  and  dut  die 
powder  of  charcoal,  at  preffcnt  ufed  in  expelling  the  carbonic  acid,  has  no  other  tSUA  than 
that  of  removing  the  earth  from  the  contad  of  the  crucible.  5.  That  barytes  and  ftrontian 
ought  henceforth  to  be  feparated  from  the  cfafs  of  eardis,  andinferted  in  that  of  alkalies,  with 
which  they  have  many  more  properties  in  common.  This  has  already  beeii  done  by  Citia&en 
Fourcroy,  in  his  new  work.  6.  That  it  is  very  projb^le,  we  (hall  hereafter  find  combina- 
tions of  barytes  and  ftrondan  with  fllex,  and  perha^ps  with  alumine. 


Csnteming 


126  Defcrtptkn  9f  a  dnk  mved  hf  the  Barmitifm 

VI. 

Concerning  ihofe  P€rpetual  Motions  which  are  producible  in  Ma^chines^  by  the  Rife  and  Fall  9f 
the  Barometer  or  tht  Thermometrical  Variations  in  the  Dimenfiom  of  Bodies, — [TV.  N%) 


I 


N  a  former  communication,  I  have  given  an  account  of  fome  of  the  dclufive  projeSs  for 
obtaining  a  perpetual  motion,  from  an  invariable  power  *.  In  that  paper  I  remarked  that  the 
flow  of  rivers,  the  viciflitudes  of  tides,  the  variations  of  winds,  the  thermometries  ,expan(ion8 
oT  folids  and  fluids,  the  rife  and  fall  of  the  mercury  in  the  barometer,  the  hygrometric  changes 
in  organized  remains,  and  every  other  of  diofe  mutations,  which  never  fail  to  take  place 
around  us,  may  be  applied  as  firft  movers  to  mills,  clocks,  and  other  engines,  and  keep 
them  going  till  worn  out.  Many  inftances  of  this  kind  of  perpetual  motion  are  feen  in  water- 
mills,  and  other  common  engines,  which  are  neceflSu'ily  confined  to  certain  loc^  iituations. — 
The  wind-mill,  though  lels  confined  with  refped  to  place,  is  the  fubjed  of  a  much  more  va- 
riable power ;  other  inflrumcnts,  flill  lefs  con^ned  with  regard  to  fituation  and  expofure,  have 
been  made,  which  are  capable  of  continuing  their  motion  without  ceafing.  Such  was  the 
dock,  or  perpetual  motion,  in  Cox's  mufeum,  which  was  (hewn  about  twenty  years  ago  in 
London*  My  former  paper  was  written  to  fhew  the  value  of  the  perpetual  motion^  ftri£^ly  fo 
called,  which  has  kx  the  mod  part  been  purfued  by  men  of  little  information.  In  the  prefent 
memoir,  I  (hall  endeavour  to  afcertain  that  of  this  fecond  kind  of  motion,  which,  becaufe  more 
promifing,  and  of  nearly  the  (ame  apparent  pradical  value,  has  been  followed  at  fome  expence 
by  men  of  higher  claims.  For  this  purpofe,  I  (hall  firft  defcribe  a  few  fchemes,  and  dien  in* 
veftigate  the  quantity  of  power  they  are  likely  to  afFord. 

Fig.  I,  Plate  6,  is  a  (ketch  of  the  firft  mover  in  a  clock,  which  formed  part  of  Cox's  mu- 
feum, which  was  fold  by  public  lottery,  about  the  year  1776,  if  my  recoUeftion  be  accurate. 
A  B  reprefents  the  furface  of  the  mercury  in  a  barometer,  the  glafs  veflel  of  which  had  the 
form  of  a  bottle  or  chemical  matrafs.  Tlie  diameter  of  the  upper  furfiace  of  the  mercury  was^ 
I  think,  about  twelve  inches.  C  D  reprefents  the  bafon  or  receptacle,  into  which  the  aper- 
ture of  AB  was  plunged.  I  fuppoie,  of  courfe,  that  the  lower  furface  of  mercury,  which  was 
expofed  to  the  preflTure  of  the  atmofphere,  was  nearly  the  (ame  as  the  upper  A  B,  as  in  fa£l  it 
appeared  to  be.  From  the  intervention  of  the  cafe,  and  other  parts  of  the  apparatus,  I. could 
only  conje£lurc  die  maimer  in  which  the  ttkSt  was  produced ;  but  this  was  afterwards  ex- 
plained to  nie  by  Mr.  Rehe  f,  who  contrived  and  made  it.  The  bafon  C  D  is  fufpendedl 
by  two  chains  K  L,  which  pafs  over  the  pullies  or  wheels  H  I,  and  are  attached  to  the  frame 
£  F ;  which  laft  is  fixed  to  the  barometer  A  B.  Let  us  now  fuppo(e  die  apparatus  to  be  at 
liberty,  and  it  will  be  clearly  (een,  that  if  the  two  maflTes  attached  to  the  oppofite  ends  of  the 
chains  K  L  be  not  preciiely  equal,  the  heavieft  will  defcend,  and  caufe  the  lighteft  to  ri(e. — 
The  ma(res  muft,  cherefbre,  be  brought  nearly  to  this  (buto  of  equality,  by  the  adjuftment  of 
weight  added  to  one  or  both  of  them.    Xn  this  (hte,  fuppofe  the  preflTure  of  the  atmo(phere  ^ 

♦  Philof.  Journal,!.  375. 

t  This  gentleman  is  at  prefent  one  of  the  board  of  infpe^lion  of  naral  works  at  the  Admiralry. 

to 


JBanmitrU  mJ  Tbernmietrk  Pirft-mtvirs^  »      \%*i 

to  increafe,  and  the  conlequence  will  be,  that  a  portion  of  the  mercury  being  foretd  from  Ae 
veflel  C  D  into  A  B,  will  render  this  laft  heavier,  and  caufe  it  to  defcend  ;  while  C  D  at 
the  fame  time  rifes.  And  on  the  other  hand,  when,  by  a  diminifhed  preifure  of  the^'^temal 
air,  the  mercury  fubfides  in  A  B,  the  veflel  C  D  will  preponderate,  and  A  B  will  rife. 
Now  the  frame  E  F,  which  is  interpofed  between  the  barometer  and  the  pullies  I  K,  is  jointed 
at  the  corners  and  alfo  at  the  places  where  it  is  attached  to  die  chain  and  the  barometer  ;  and 
the  inner  edges  of  the  upright  pieces  £,  F  are  formed  into  teeth  like  tbofe  of  a  faw,  the  flopes 
of  which  lie  in  oppofite  direftions,  as  is  (hewn  in  the  figure.  The  wheel  G,  which  is  placed 
between  thefe  bars,  is  alfo  toothed  in  the  fame  manner ;  and  its  diameter  is  fuch,  that  when  the 
teeth  on  one  fide,  as  for  example  E,  are  engaged,  thofe  on  the  other  fide,  F,  may  be  free ;  but 
it  is  too  large  to  admit  of  both  fides  being  difengaged  at  once.  The  wheel  G  is  prevented 
by  a  click  from  moving  in  the  diredion  oppofite  to  that  which  may  be  produced  by  the  ^Si\on 
•f  the  bars  E  and  F.  Hence  the  play  of  the  machine  is  evident.  When  the  preflure  of  the 
atmofphere  diminifhes  and  the  barometer  rifes  from  its  ciftern,  the  fide  E  of  the  frame  will 
move  the  wheel  G  through  a  greater  or  lefs  fpace,  according  to  the  variation  \  and  when,  on 
the  contrary,  it  fiills,  the  teeth  £  will  be  drawn  out  of  their  bearing,  and  thofe  of  F  will  be 
dirown  into  the  wheel,  and  ftill  produce  a  motion  of  the  (ame  kind ;  the  joints  of  the  frame 
£  F  allowing  it  to  change  its  figure  enough  for  this  purpofe.  It  is  hardly  neceflary  to  remark^ 
that  this  wheel  G  being  connected  with  the  clock,  ferves  to  wind  it  up,  and  that  the  clock,  is 
conftruded  to  go  for  a  much  greater  number  of  days  than  the  barometer  has  ever  beenknowu 
to  remain  ftationary. 

The  ingenious  mechanic  will  readily  form  a  notion  of  many  other  methods,  of  applying  the 
variations  of  the  barometer  to  fimilar  objects.  The  wheel-barometer  of  Robert  Hook,  as 
well  as  another  contrivance,  in  ^ich  the  barometer  and  its  ciftern  are  placed  at  the 'different 
extremities  of  an  inclined  lever,  may  Kkewife  be  u(ed  for  this  purpofe. 

Several  artifts  have  exerted  their  induftry,  in  attempts  to  apply  the  variations  produced  by^ 
change  of  temperature  in  bodies  as  a  firft  mover.  If  a  dietmometer  be  fufpended  by  its  centre 
of  gravity  is  fuch  a  manner,  that  the  tube  may  lie  nearly  horizontal ;  the  daily  variations  in  the 
bulk  of  the  mercury  will  caufe  a  preponderance  on  the  one  fide  or  the  other,  accordingly  as  the 
temperature  is  higher  or  lower,  than  it  was  at  the  original  fixing  of  the  centre  of  fufpenfion. 
The  thermometer  may  contain  mercury  or  any  other  fluid,  or  it  may  confift  of  air  confined  by 
mercury,  as  in  the  manometer.  In  diis  contrivance,  the  great  and  frequent  ranges  of  variation 
affords  much  promife  of  utility.  The  limits  of  convenient  or  pra&icable  power  from  change 
^  equilibrium  in  a  fluid  thermomeler,  ^11  hereafter  bd  examined.  A  much  greater  force 
fecms  to  offer  itfelf,  in  the  power  by  whiph  the  expanfion  is  produced  ;  but  the  difficulty  of 
forming  a  pifton  or  other  apparatus  for  ccC^ning  fluids,  win  probably  conftitute  an  infiirmount- 
able  impediment  to  this  method.  4S' 

The  folid  thermometer  does  not  framthe  &me  dSflkulty.  Fig.  2,  reprefents  a  fecies  of  ex* 
jonfion-bars,  each  confift  ing  of  a  plate  of  brafs,  foldered  to  another  of  fteel,  and  pofTcfling  the 
propeit|  of  bending  by  change  of  temperature,,  according  to  the  laws  akeady  explained  in  thia 

worJu. 


•' 


work  *.  •  If  the  fteelface  of  C  A  be  itppermoft,  and  the  end  C  be  fixed  to  C  B,  the  extre- 
mity A  will  rife  from  B,  when  the  temperature  is  elevated ;  and  if  ihe  fucceeding  bars  be 
iimilarly  fixed  above  each  other,  as  in  the  figure,  the  whole  fyfteTi  will  occupy  a  greater 
length,  or  elevation,  above  C  B,  when  heated,  than  when  cold.  Another  more  convenient  mc* 
ihod  of  difpofing  the  bars  is  (hewn  in  fig.  3 ;  in  this,  the  bars  are  fixed  together  at  the  middle, 
With  the  bra&  faces  turned  towards  each  other.  Each  bar  has  a  flight  curvature  (much  lefs 
than  is  here  (hewn),  which  will  be  increafed  by  heat,  and  by  that  means  caufe  the  diftance  be- 
tween the  middle  of  two  extreme  bars  to  be  greater  than  it  would  be  at  a  lower  temperature. 

Thefe  caufes  of  a£kion  may  be  applied  to  machinery  by  various  contrivances,  fome  of  which 
ferve  toincreafe  the  length  of  range,  but  add  nothing  to  the  power.  This  laft,  no  doubt,  is  an 
.  objedl  of  convenience,  according  to  the  effect  intended  to  be  produced.  The  only  method  of 
adding  to  the  power  will  confift  in  increafing  the  number  of  the  bars.  Fig.  4,  reprefents  a 
fyftem  for  this  purpofe,  which  is  the  fimpleft  and  moft  convenient  that  his  occurred  to  me.  A  C 
reprefents  the  circumference  of  a  barrel,  refembling  thoie  in  which  the  main  fprings  of  clocks 
are  put ;  the  length  and  diameter  of  which  may  be  varied,  according  fo  the  power  intended  to 
be  gained.  To  this  external  part  is  fixed  a  ratchet-wheel  to  recfive  the  click  C,  which 
confines  its  motion  to  one  dire^on.  At  A  is  fixed  a  plate  to  receive  the  a<5lion  of  the  ex- 
panfion-pieces.  B  D  is  an  internal  cylinder  of  the  iame  kind,  which  is  alfo  confined  by  a 
ratchet-wheel  and  click  to  move  only  in  the  fame  diredion  as  the  outer  part  A  C.  It  is  not 
neceflary  to  defcribe  the  operative  arrangements,  by  which  thefe  two  cylinders  are  diipofed,  fo 
as  to  move  on  the  fame  axis,  and  the  ends  duly  applied,  fo  as  to  form  one  box ;  while  the  in- 
terior and  exterior  parts  allowed  to  move  independent  of  each  other.  At  B  is  fixed  a.  plate, 
by  which  the  adiionof  the  expanfion-pieces  is  communicated  to  the  inner  cylinder.  A  feries 
of  bars,  fimilar  to  thofe  delineated  in  fig.  3,  are  difpofed  in  the  fpace  between  the  two  cylinders, 
the  greateft  part  of  which  they  occupy,  leaving  only  fuch  an  interval  between  A  and  B,  as 
may  be  fufficient  to  allow  for  the  motion  of  the  bars.  In  this  interval  is  placed  a  fpring,  tend-, 
ing  to  caufe  A  and  B  to  recede  from  each  other :  and  laftly,  there  are  fide-pins  proceeding  firom 
the  places  of  jundion  of  every  pair  of  bars,  which  refpedivdy  pafs  through  circular  grooves  in 
the  caps,  and  prevent  the  motion  of  the  bars  from  being  interrupted  or  impeded  by  their 
touching  either  the  inner  or  the  outer  cylinders.  £  reprefents  a  whed»  which  is  fuppofed  to 
be  connefied  by  tooth-work,  or  otherwife,  with  the  &ce  of  the  external  cylinder,  and  may  be 
confidered  as  the  machinery  intended  to  be  moved.  Or  otherwife,  if  the  clicks  C  and  D, 
with  the  teeth  they  zSt  upon,  be  reverfed,  and  the  interior  cylinder  be  fixed  to  the  axis  itfelf, 
that  axis  may  be  ufed  as  the  firft  mover* 

♦  Philof.  Journal,  I.  6s.  576. 

{Tt  ii  C99uludtd  in  our  mxU) 

ChemUal 


Cmp$imd  Qburt  fndncid  $9  CaHim  hj  ibi  Oxjde  §/  Inn.  129 

VIL 

Chimcat  Confidirati^m  $n  thi  U^i  cf  tU  Oxydts  ff  Irm  in  ihi  dying  tf  Cotton.    By  J.  A. 

Chaftal. 


A 


^Omcludid  front  f^igt  93;)^ 


F  tfie  iron  be  precipitated  from  a  folution  radier  ftrong  by  alkaline  liquor,  marking-bciweei^ 
five  and  fix  degrees  of  the  areometer  of  Baume,  the  produd  will  be  a  bluilh  green  magma. 
Gotton  macerated  in  this  precipitate  acquires  at  firft  a  dirty  irregular  green  tinge ;  but  fimple 
cxpofure  to  th«  air  converts  it  to  a  yellow,,  in  a  very  (hort  time,  of  a  very  deep  (hade- 
It  is  by  a  procefs  nearly  (imilar  to  this,  that  the  ochre  or  rud  colour  of  the  fbops  is  formed. 
But  thefe  colours  are  attended  with  various  inconveniences,     i.  They  either  corrode  the 
the  clotbor  injure  its  durability-    2.  This-  colour  is  harfh,  dUagreeable,  and  cannot  eafily  be 
combined  with-  the  (bft  colours  afforded  by  vegetables. 

I  was  defirous  of  remedying  thefe  inconveniences,  and  fiicceeded  by  the  following  treatments 
I  wQrk  the  cotton  in>  a  cold- folution,. marking  three  degrees  ((jpecific  gravity  1,02),  dien 
carefully  wring  it  with  die  pin,  and  afterwards  plunge  it  in  a  (blation.of  potafh  at  two  degrees 
(1,015))  into  which  fulphate  of  alumine  has  been  poured  to  iaturation.  By  diis  means  the  colour 
is  brightened^  and  becomes  infinitely  finer^fofter,  and'more  agreeable  y — the  fulphate  does  not 
attack  the  body  of  the  fluff; — and  after  having  left  the  cotton  in  the  (fecond)  bath  for  four 
or  five  hours,  it  is  taken  out  to  be  prefled,  waflied,  and  dried. 

By  .this  procefs,  everyihade  which  can  be  defired  may  be  obtained  by  graduating  die  ftrengdi 
of  the  folutions.  The  famples  which  I  prefent^to  the  inftitute  are  prepared  according  to  this 
method.  This  fimple  procefs,  of  which  the  theory  wilt  preient  itfelf  to  the  mjnd  of  every 
chemift,  poflefies  the  advantage  of  affording  a  very  agreeable,  very  folid,  and  parti  Ailarly  cheap, 
colour.  I  have  ufed  it  widi  advantage  for  nankeens,  of  which  the  colour  is  infinitely  more 
fixed  than  that  of  the  Engli/h  nankeens.  It  has  the  advantage  over  them  in  refifting  alkalies^ 
and  the  only  fiiult  I  know  in  it  is  that  of  acquiring  a  brown  colour  by  the  adion  of  aftringents. 

I  was  for  fome  time  of  opinion,  that  it  might  be  polfible  to  combine  diis  yellow  with  the 
Uue  of  indigo,  to  obtaun.a  folid  cobur.  But  hitherto  my  expeditions  have  not  been  realised^ 
and  the  cefults  of  the  trials  I  have  made  are,  that  theie  is  not  a  fuflkient  affinity  between  the 
blue  of  indigo  and  the  oxydes  of  iron.  I  obtained  only  a  dirty,,  earthy,  vtty.  deep,  and  unequal 
green  colour. 

The  oxyde  of  iron,  on  the  contrary,  combines  very  eafily  with  the  red  of  nudder,  and 
affords  a  light  violet  prune  odour  of  very  extenfive  and  advantageous  ufe  in  cotton  manur- 
fii^ries. 

But  if  thefe  two.  colours  be  applied  to  cotton  without  employing  a  mordant  capable  of  fixing 
the  latter,  the  colour  will  not  only  remain  dull  and  difagreeable,  from  the  impoffibility  of 
brightening  it,  but  it  will  likewiie  have  the  very  great  inconvenience  of  not  refifting  alkalies* 
It  is  proper,,  therefore,  to  begin  the  operation  in  the  fame  maimer  as  when  cottons  are 
prepared  to  receive  the  Adrianople  red ;  and  when  the  goods  are  brought  as  fiur  as  to  the 
operation^of  galling,  they  are  to  be  paffed  into  a  folutioQ  of  iron,  more  or  left  charged,  accord- 
Vol.*  in.— JuMi  1799^  S  iog 


•  X 


\ 


130  Compound  Colours  proiuai  on  Cotton  ty  the  X^xyae  of  Tron. 

ing  to  the  nature  of  the  violet  which  may  be  JcGred.     The  cotton  muft  be  carefully  waflied 
and  niaddered  twice  m  facceffion,  aftci  wkich  it  is  brightened  in  a  balh  rf  foapw 

When  a  true  violet  of  a  foft  and  firm  cbhnir  is  required,  the  folution  of  iron  is  not  to  be 
ufed  till  after  the  galling.  The  iroix  is  then  precipitated  in  a  bluifli  oxyde,  which  combining 
with  the  red  of  the  madder  affords  a  fuperb  violet,  more  or  lefs  deep  according  to  the  ftrei^gth 

■  ■  •  •  •     • 

oftfte  galling  And  of  the  martial  folutkm. 

It  is  very  diflieuk  t6  obtain  an  unifcrfn  cqIoup  by  this  proceft ;  and  a  very  even  violet  is 
corffider^d  in  the  manu&Aories  as  a  mafter*piece  of  the  art.  It  is  gefieitdly  imagined^  that 
this  important  problem  of  the  art  of  dying  c^n  only  be  folvcd  by  weU-coiMki6led  manipuiaciofis* 
But  I  am  weH  convinced  that  the  great  eaofe  of  die  onev«nnefs  of  this  dye  is,  that  the  iron 
depofited  upon  the  cotton  receives  an  oxydiation  by  mere  ospofure  to  the  air,  which  varies  in 
€tit  different  partis  of  tKe  cotton.  The  thvradt  wiifch  are  at  the  outfide  of  the  mafs  become 
ftrongly  oxyded,  while  the  interior  part,  being  defended  tirom  die  a£Hon  of  die  air,  undergoes  no 
change.  Whence  it  foflows,  t^t  die  inner  part  afcquires  a  ^m  fliadses  white  the  outer  fur&ce 
|iitfents  a  violet  alnK>ft  black.  The  only  means  of  remedying  this  inconvenience,  is  to  wafli 
die  cotton  on  taking  ft  out  of  die  folution  of  iron,  and  to  madder  it  Wbile  wet.  The  cotton  is 
^s  rendered  more  ty^  and  velvety. 

The  folvents  for  iron  are  nearly  the  fame  for  diis  colMr,  as  for  the  yettow  of  which  we  have 
ahridy  treated. 

I  fupprefs  all  obfervation  on  the  manipukdons,  in  order  to  cOiiflne  myfeif  to  mere  diemical 
report ,  and  on  this  confideration,  I  fhall  add  an  obfervadon  to  diraS  the  ardft  in  die  brighten- 
ing of  violet  upon  eotton. 

The  red  of  madder,  and  the  oxyde  of  iron,  befaig  depofited  mi  the  fluff,  determine  the  viokt 
colour.  This  colour  inclines  to  red  or  blue,  accordingly  as  the  one  or  the  other  of  the  two 
principles  predothinates.  The  dyer  knows  by  experience,  how  difficult  it  is  to  obtain  a  com* 
binadon  which  fhall  produce  any  defired  tone  or  colour ;  particularly,  when  it  is  required  to 
be  uniform,  bright,  and  folid.  It  may,  neverdieleis,  be  efFeded,  not  only  by  varying  the  pro« 
pordons  of  the  two  principle  but  alfo  by  varying  the  proceis  of  brightening.  It  is  only  ne- 
ceffiiry  to  know  die  following  fads :  namely,  that  foda  deflro}  s  the  iron,  while  foap  by  flrong 
boiling  attacks  the  red  of  the  madder  in  preference.  Hence  the  dye  may  be  made  to  inciinc 
to  red  or  bhie,  accordingly  as  the  brightening  is  efFe£led  widi  one  or  die  odier  of  diefe 
mordants.  Thus  cotton  taken  out  of  the  madder,  waflied,  and  boiled  with  30,00  parts  of 
(bap,  will  afford  a  fuperb  videt }  though,  if  fbdahad  been  ufed,  it  would  have  turned  out  merely 
a  prune  colour. 

The  oxyde  of  iron  precipitated  upon  piece-goods,  unites  ftill  more  advantageoufly  widi 
die  yellow  afforded  by  aflringents;  and  an  infinite  number  of  fhades  may  be  obtained  by  vary- 
ing, the  foire  of  the  mordants.  In  this  cafe,  it  is  left  a  combinadoU}  or  fohtdOn,  of  princi  piles, 
than  a  fimple  mixture,  or  juxtapofirion  of  the  colouring  matters  upon  the  ^uff.  The  okyde 
of  iron  may  be  more  intimately  combined  with  the  afbingent  principle  by  a  boiling  heat, 
which  brings  it  to  die  fbte  of  black  oxyde,  as  our  colleague  Berthollet  has  obferved. 

It  Is  alfo  pofBble  to  render  theic  fimc  colours  brown>  and  give  diem  a  variety  of  dnges, 

•  -      .  'from 


Oh  tie  EffiS  tf^ringm  FigitahUs  h  Dpng.  I31 

fcom  light  grey  to  .deep  black  ;  limply  by  paffing  the  cottons,  impregnated  with  the  aftringent 
principle,  into  a  folution  of  iron.  The  oxyde  is  then  precipitated  by  the  principle  which  is 
fix^d  in  the  ftufF. 

It  is  an  obfervation  which  nuy  become  of  high  value  in  the  art  of  dying,  that  the  aftringent 
vegetables  moft  commonly  ufed  afford  a  colour  which  is  not  very  bright,  but  of  high  value  for 
its  durability.  This  yellow  colour  is  brightened  in  the  feries  of  vegetables,  in  proportion  as 
the  alUingent  principle  is  lefs  in  quantity,  and  the  livelinefs  of  the  colour  is  alfo  increafed  in 
the  fame  proportion.  It  is,  therefore,  difficult  to  obtain  yellow  colours  which  (hall  be  at  the 
fame  time  folid  and  bright.  Thefe  two  valuable  qualities  are  inverfely  proportioned  to  each 
other.  But  it  is  poffible  to  join  thefe  colouring  principles  in  fuch  a  manner  as  to  add  brightneis 
to  (olldity.  Green  oak-bark  joins  perfeSly  with  woad,  and  fumach  with  quercitron.  By 
this  mixture,  we  may  fucceed  in  combining  with  the  oxyde  of  iron  fuch  vegetable  colours  as 
unite  durability  with  brightnefs. 

I  fliall  conclude  thefe  obfervations  with  a  remark  concerning  the  u(S  of  aftringents  in  the 
dying  of  cotton. 

It  has  been  pretended,  that  by  increafing  the  proportions  of  fumach,  or  the  bark  of  alder, 
or  oak,  it  may  be  praflicable  to  fupply  the  place  of  galls  in  the  red  dye  for  cotton.  I  ihould 
be  fo  much  the  more  gratified  if  this  were  true,  as  the  galls  confiderably  add  to  the  expence  of 
our  colours,  and  fumach  may  be  had  at  a  low  price,  becaufe  it  grows  almoft  every  where  in 
the  dry  fituations  of  our  fouthern  climates  ;  but  I  can  affirm  that  the  fubftitution  is  impoffible, 
however  large  the  dofe  of  this  aftringent  may  be  ;  for  the  colour  is  much  palsr,  with  le(s  body 
^nd  durability.  I  know  that  this  is  not  the  cafe  with  regard  to  wool  and  filk,  in  which  this 
article  is  ufed  with  fuccefs ;  and  in  giving  an  account  of  this  difference,  I  think  it  may  be  af- 
Cribed  to  the  nature  of  the  nut-gall  itfelf  i.  The  acid,  which  it  contains  exclufively  of  the 
Other  aftringents,  as  Berthollet  has  proved,  fecilitates  the  decompofition  of  the  foap,  with 
which  the  colours  have  been  impregnated ;  and  then  the  oil  remains  fixed  in  their  texture  in 
a  much  larger  quantity,  and  more  intimately  combined.  2.  The  nut-gall,  which  owes  its 
development  to  animal  bodies,  retains  a  character  of  animalization,  which  it  tranfmits  to  the 
vegetable  piece ;  and  by  that  means,  increafes  its  affinities  with  the  colouring  principle  of  the 
madder ;  for  it  is  known  how  ufeful  animal  fubftances  are  to  facilitate  this  combination.  This 
animalization  becomes  ufelefs  in  operations  upon  wool  or  filk. 

VIII. 

JkcQtmt  pf  ibi  EMfitkm^s  (f  Gtizin  CzouETj  w  tbi  iiffkrwt  StaUs  rf  Iron^  and  its  CoH' 

wrjm  into  Gaft^Jieil*. 


T 


HE  learned  reporter  begins  his  account,  by  giving  an  hiftorical  iketch  of  die  fcientific 
and  correA  information  we  poITefs,  relpe£ting  die  art  of  fbel-making.     He  ftates,  that  from 

*  From  the  report  of  Citizen  Gujcon,  made  to  the  National  Inftitute  of  France,  OA  i6th  Meffidor  in  the 
jcar  VI.  (J^^y  4>  *79^)»  nd^rt^  >b  the  Annidet  de  Chtmit,  XXVIII.  19. 

S  2  dif 


t^2  Experiments  m  Steel,  er  ihe  QnAtnatlons 

the  time  when  the  labours  of  Reaumur  had  enlightened  the  pradice  of  making  natural  ftee% 
and  fteel  by  cementation,  the  theory  remained  ftationary,  notwithftanding  die  numerous  and 
valuable  experiments  of  Bergman^  Rinmann«  Prieftley,  ice.  until  the  appearance  of  the  ex- 
celtentmemoir  of  Vandermonde,  BeKhuIlet)  and  Monge,  in  the  Memoirs  of  the  Academy  of 
Sciences  for  i^6.  That  theEnglifh,  who  had  long  fupplied  the  European  market  with  fteel  of 
cementation,  remained  alfo  in  the  exclufi ve  pofleffion  of  the  article  known  by  the  name  of  caft- 
fteel,  which,  though  confined  to  ceruin  fine  works  \  Is,  neverthelefs,  a  very  valuable  branch 
of  national  induftry ;  that  various  experimentsliave  been  made  with  fuccefs,  on  a  confined  (bale, 
in  France  to  imitate  this  produA,  fince  the  time  when  Jars.publiflied  an  account  of  the  me- 
thod ufed  at  Shefiield  ;  but  that  from  a  W^t  of  precifion  in  the  narrations  of  thefe  procefies,  and 
the  difference  which  is,  with  jullicey  confidered  to  fubfift  between  the  experiments  of  thel». 
boratory,  and  thofe  of  the  manufii&urer  in  his  extenfive  operations,  the  art  of  making  caft- 
fleel  was  confidered,  hyfhc  mod  eminent  French  chemifts,  as  very  far  from  being  publicly  known : 
and  Vandermonde,  Monge,  and  BerthoUet,  notwidiftanding  their  acquaintance  with  thele 
fads,  thought  fit  to  declare,  in  the  public  inftrudions  drawn  up  by  order  of  the  committees 
of  lafety,  that  they  could  oiFer  nothing  but  conjedures  on  the  fubjed  f.  In  this  fituation  was 
the  knowledge  of  the  chemlfts^  and  jnamifeifturers  of  France,  when  Citizen  Clouet  refumed 
his  experiments  on  a  larger  Tcale  at  thetioufe  of  the  Confervatory  of  Arts,  and  the  mineralogical 
fchool  at  Paris,  on  the  fufion  of  various  kinds  of  fteel,  and  the  immediate  converfion  of  iron 
into  caft-ftecl. 

On  this  fubjed,  the  author  delivered  a  memoir  to  the  Inftitute  of  France,  which  forms 
the  fubje(St  of  Guyton's  report.  He  firft  treats  of  the  combinations  of  iron  and  chsUrcoal* 
One  thirty-fecond  part  of  charcoal  is  fufficient,  as  he  affirms,  to  convert  the  iron  intb  fted; 
one-fixth  part  of  the  weight  of  the  iron  affords  a  fteelwhich  is  more  fufible,  but  ftill  malleable ; 
and,  after  this  term,  it  becomes  nearer  to  the  ftate  of  caft-iron,  and  no  longer  pofleflfes  enough 
of  tenacity.  By  augmenting  the  dofe  of  charcoal,  the  fufibility  is  increafiKi  $  and,  at  laft,  it  ac- 
quires the  ftate  of  grey  caft-iron. 

The  particular  caft-iron,  which  refults  from  the  combination  of  iron  and  glafs,  forms  the 
fecond  objeft  upon  which  the  attention  of  Citizen  Clouet  was  fixed.  The  glafs  enters  but  in 
a  finall  quantity  into  this  compound,  notwithftanding  which  the  properties  of  the  mafs  are 
changed.  This  iron,  though  very  foft  to  the  file,  if  heated  merely  to  cherry  red,  flies  in  pieces 
under  the  hammer :  the  caft  ingot  contrails  greatly  in  cooling  ;  and  when,  by  careful  manage- 
ment, it  has  been  made  into  bars,  the  operation  of  hardening  gives  them  die  grain  of  fleel,  and 
renders  them  brittle,  without  adding  to  their  hardnefs. 

Charcoal  in  powdery  added  to^e  glafs,  changes  the  refult,  and  increaies  die  fufibility;  but  the 
nature  of  the  produ£t  is  gready  influenced  by  the  dofe  of  thefe  ingredients.  From  one-joth  to 
one^20th  part  of  the  iron  .affords  fteel  ^capahle  of  a  high  degree  of  hardnefii,  which  may  be 
forged  at  a  low  red  hear,  and  has  all  the  properties  of  caft-fleel.  If  more  charcoal  be 
employed,  the  produds  refemble  thofe  of  the  fmdting-furnaee. 

*  It  it  ufed  in  a  great  variety  of  common  tools  and  works  in  this  country  .^N. 
^  PhiL  Jonmal  11.  102. 

The 


Sf  Iron^  Carhmi  and  Vttndus  Maitir.  133 

"  The  attraSion  of  iron  for  carbone,  continues  Citizen  Clouet,  is  fuch  diat,  at  a  very  high 
temperature,  it  will  take  it  even  from  oxygen.  He  proves  this  by  the  following  experiments : 
Let  iron,  in  fmall  pieces,  be  put  into  a  crucible  with  a  mixture  of  equal  parts  of  carbonate  of 
Time  and  clay;  let  the  heat  be  urged  to  the  degree  neceflary  to^weld  iron,  and  kept  at  that 
elevation  for  an  hour,  or  more,  according  to  the  fize  of  the  crucible  :  the  metal  being  then 
poured  into  an  ingot  mould,  will  prove  to  be  fteel  of  the  fame  quality  as  caft-fteel. 

The  oxydes  of  iron  are  equally  fufceptible  of  paffing  d^rough  the  dates  of  ioft  iron,  fted, 

and  fufible  or  caft-iron,  according  to  the  proportions  of  coal  made  ufe  of.    The  black  oxyde  of 

iron,  of  which  the  ftate  appears  to  be  the  moft  conftant,  becomes  iron  when  heated  in  the 

crucible  with  an  equal  bulk  of  charcoal  powder  :  a  double  quantity  affords  fteel.    A  progreffive 

augmentation  imparts  the  characters  of  the  white  and  the  grey  caft-iron. 

Laftly,  Citizen  Clouet  obferved  the  fame  tranfitions  dependant  on  die  refpedive  quantides, 
by  heating  caft-iron,  and  the  oxyde  of  iron ;  caft-iron  and  forged-iron  ;  the  oxyde  of  iron  and 
iron ;  the  oxyde  of  iron  and  fteel.  No  more  dien  one-fifth  of  caft-iron  is  neceilary  to 
convert  bar-iron  into  fteel. 

Iron  and  its  oxyde  do  not  intimately  unite  together.  The  black  oxyde^  mixed  with  half  die 
quantity  of  charcoal  which  would  be  necefiary  for  its  reduction,  affords  iron*  which  is  foft, 
pdfieffing  little  tenacity,  of  a  black  colour,  and  indiftin<^  fradure. 

One-fixth  of  oxyde  reftores  common  fteel  to  the  ftate  of  iron,  by  heating  them  together  im 
the  forge,  or  in  the  way  of  cementation. 

At  the  end  of  his  memoir.  Citizen  Clouet  has  given  obfervations  on  the  manner  of  producing 
caft-fteel,  and  the  furnances  proper  for  this  effeft. 

He  determines  die  nature  of  the  fluxes,  the  degree  of  heat,  the  quality  of  the  crucibles,  die 
precautions  for  cafting  the  ingot,  the  method  of  forging  this  kind  of  fteel,  the  proceflTes  to  be 
followed  in  experiments  at  the  forge  upon  two  kilogrammes  of  the  materials,  and  the  propor* 
tions  to  he  given  to  a  reverberatory  furnace  capable  of  heating  four  crucibles,  each  containing 
1 2  or  13  kilogrammes  6f  fteel  (about  a8  pounds  avoirdupois  each  crucible). 

He  remarks,  diat  die  mere  ingredients  of  (aline  glafs  cannot  be  diredly  ufed  in  this  procels( 
that  glaffes,  which  are  too  fufible,  render  the  fteel  difficult  to  forge ;  that  fbel,  kept  for  a  long 
time  in  fufion,  takes  up  more  glafs  than  is  proper }  and,  laftly,  that  the  melted  matter  muft 
be  ftirred,  and  the  glafs  carefully  taken  off  before  cafting,  in  order  to  prevent  its  mixing  with 
die  fteel. 

The  Commiffaries  of  thelnftitute  proceeded  to  repeat  and  verify  the  eaqieriments  of  Citizen 

Clouet.  Thefe  operations,  which  are  related  at  length,  were  as  follows,     i.  Six  he&ogrammes 

(about  21  oa^  avoirdupois)  of  filings  of  farrier's  nails,  and  four  of  a  mixture  of  equal  parts  of 

white  marble,  or  carbonate  of  Ume,  and  baked  clay  of  an  Heffian  crucible,  both  reduced  to 

powder,  were  well  blended  together,  and  expo&d  to  the  heat  of  a  forge-furnace  urged  by  three 

bellows-pipes  for  an  hour  and  a  half.     The  crucible  failed  at  the  firft  experiment;  but,  on 

tepetitioo,  a  bar  of  fteel  was  afforded,     a.  Upon  making  the  experiment  widi  Macquer's 

furnace,  die  fofion  was  not  complete,  though  die  fire  had  been  urged  to  151^  of  Wedgwood. 

3*  InanodiercxccHcntwind-fumace,  367  grammct  (about  13  oz. avoirdupois)  of  fmall-draW 

iron 


13^  HiJUiy  Md  Sstfirhimts  4H  StaUtuiiing. 

iron  naSs^  tod  24^  grammes  (idiout  Si  og.  avoirdupois)  ol  a  ouxture  of  carbonalt  of  lime  and 
fcoked  day^  were  expofed  lo  ftroog  heat  for  an  hour,  \rfien  the  fiifioa  was  judged  to  be  complete^ 
and  after  removing  the  vitreous  matter  the  iagot  was  poured  put.  From  the  effed  produced 
en  two  pjTOikietric  piedte,  it  was  judged  that  the  fleel  had  undergone  an  heat  of  150  degrees. 
'f  his  fteel  had  all  the  properties  of  caft«fleel,  and  was  made  into  razors  by  Citizen  Lepetitwalie» 
vriio  found  it  of  a  good  qualit/,  eafy  to  be  workedf  and  capable  of  bearing  a  comparifon 
MA  dwcaft-fted  marioed  Mar^^ni  B.  Hkmifmutu. 

Upon  thefe  fafts,  the  rqwrter  ohferves,  that  fioce  iron  does  not  become  fleel  but  by  taking 
up  about  0,2013  ^  ^  weight  of  carbone*,  and  in  the  prefent  proce(s  it  exifts  only  in  the 
form  of  carbonic  acid,  this  acid  muft  confoquently  be  decompofed ;  which  happens,  as  the 
reporter  obferves,  by  means  of  a  combination  between  its  principles  refpeAively  and  certain 
adequate  portiooi  of  the  iron,  dnt  is  to  lay,  the  oxygen  of  the  acid  coanbines  with  part  of. 
fte  iron,  and  forms  an  oxyde  with  4diich  the  vitreous  flux  becomes  charged,  and  the  car  bone 
OimbhMS  with  tbe  reft  of  dieirotti,aiid  forms  AeeL    Heiiee  it  may  be  inferred,  that  this  new 
procefs  muft  be  attended  vrith  a  lofs  of  fo  much  more  confequence,  as  it  is  necefiary  to  ufe  iron 
of  die  beft  qudity  for  makulg  fieel.    Bu^  on  this  head,  the  ipgporter  takes  notice  that  the  4ofa 
in  die  ttcperimcnt  with  the  wind-fiiroace  wi|s  not  fuite  one^twelfth  part ;  aud,  in  aoodier  ta^gm^ 
ment,  by  Vauquelin,  the  lots  was  iefs  than  one  twenty-fecpndpart ;  a  lofs,  which  he  ohfePKes, 
will  be  well  repahi  by  die  increafed  valtte  of  die  produft,  and  ouy  reafonaUy  be  expeded  ta 
be  ftill  lefi  in  operations  on  a  large  fcale.    He  thinks,  moreover,  that  diis  new  method  xnxjf^ 
probably  tum  out  of  hig^  value  for  prddudi^  fteel  of  uniform  quality  with  rctgard  to  tfie  dofe 
of  carbone.    For  he  thinks  that  this  quantity,  or  proportion,  is  likely  to  be  determined  by  the 
equilibrium  of  die  forces  of  affinity  which  caufe  die  decompoCdon  of  the  carbonic  acid.    Orj^ 
in  odier  wordsi  if  we  foppofe  an  indefinite  quandty  of  carbonic  acid  to  be  prefented  at  an 
risvalcd  temperature  to  a  mais  of  iron  not  greater  than  could  be  converted  by  the  dofe  of 
carbooe  eontaioed  in  that  acid,  the  iron  will  form  two  combinadons,  the  oxyde  and  tbe.fted  i 
and  it  is  conceived  diat  the  equilibrium  between  the  attrai^on  which  tends  to  preferve  the 
anion  of  principles  in  carbonic  acid,  and  thole  which  are  exerted,  between  the  iron  and  thofo 
principles  will  prote  to  be  fuch  that  the  carburet  of  iron  will  be  formed  precisely  in  thofe 
|ilx>pordoas  which  conftitute  good  caft-fteel.  This  fiit^e^  which  certainly  (hews  die  acutene& 
of  Cidsen  Ouyton  with  regard  to  the  do&-iiies  of  chemical  attradlion,  muft  be  decided  hj 
die  teft  of  experiment 

The  report  is  cooduded  with  k  fummary  of  the  IwBts  and  obiervadons  it  contains,  together 
widi  an  inference,  that  the  immediate  converfipn  of  iron  into  fteel,  without  ufing  charcoal,  is  ^ 
grettt  and^uaMe  difeovery  with  regard  to  the  increafe  of  aadonal  iad^ftry ;  that  there  is  no 
ibUbt  but  the  pracefi  will  fiicceed  in  the  hrge  way,  and  that  Citizen  Clouct  is  entitled  to  a 
^blic  reccHtopence  for  his  liberal,  and  unreferved  communications* 
That  all  die  ilAaiare  of  high  value  to  rcienceyand  that  the  obfervadoa  re(pe%ng  the  combi- 

*  This  quamicy  (upwards  of  one-fifch)  fomuch  Exceeds  thy  addhieii'lKfhitbirmi  ik  fbted  to  ^ia^by 
coBverfioB  into  ftte],  thsl  I  fuppofe  it  to  be  o.^otj  in  the  ccmi^fMt*3r  o4r'htilrilre4  pans  of  itnu  Jreu  isKckoac4 
lo  gdo  iiUmt  a  litUe  nitet'lhaa  kilf  a  poimd-hi  iIkk  IrattiirMl;  w«t|^t  by.ctnrfl|t|wai.«<^ . 


Pi^  fir  Bfiffing  0  Bri4ge  0if  LMdtm,  i^e^  ^ 

tifttio)!  jdf  vftreovs  mttlcr  with  iron,  as  well  as  cbiit  which  (hows  that  carbonic  acid  can  producf 
the  fleel  cont'erfion,  uc  new  and  important,  cannot  be  qMoflioned ;  but  whether  the  ufe  9( 
carbonate  of  lime  and  clajr,  which  is  attended  with  fome  lofs,  may  be  preferable  to  vitreous  flux 
and  eoal,  which  afford  (bme  finaU  additional  wtight,  is  WK  jet,  ai  it  ihould  ^>pear,  decided 
by  the  adual  operations. 

''  ■      pill  >■  ^'T?^r"^i^5S55fSSsss8S5sr*"*^*™"       L  ■  . '^'*^^T*r' 11     ■!        II  '"'"T^nsg 

SCIENTIFIC  NEfFS. 

JUetters  to  a  Mwchant  on  ^  Improvement  of  the  Port  pf  London,  demonftrating  its  Prac« 
:  /tioability  without  Wet  Docks,  or  any  additional  Burdens  being  laid  on  Shipping,  and  at  4 
'  il  Idfs  Sxpence  of  Time  and  Money  than  any  other  Plan  propofed.    By   C.  Dodd, 
.   Enginecnr,  1799. 

'  THIS  o£bvo  pamphlet,  cf  mnetien  pages,  has  been  given  away  by  die  pubUQier  of  the  au*', 
fSMr*%  former  Reports  {Tzyht  in  Holbora)*  The  plan  confifts  in  building  a  ncwbridgc»  in* 
dead  of,  or  upon,  the  prefent  Loedon-bridgf;,  which  (hall  confift  of  one  principal  centre  arcb^ 
formed  of  iron,  one  hundred  feet  from  low  Wdler  to  the  cfown  of  the  arch,  defcrihing  a  fpan-  of 
^00  foet,  with  iwo  large  fliore  ait^es  of  80  feet  (pani  ss  near  to  the  butment  on  each  ibore  as 
advifeable,  for  keeping  deep  water  abogfide  die  prefent  below-bridge  quays.  Among  die  aid|« 
vantages  of  the  ftru^re^  the  principal  is,  that  it  will  admit  fhipping  to  pafs  through,  and  arr 
rive  at  the  (pace  between  London  tnd  Biacjcfriars-bridge,  which,  as  the  engineer  obferves^ 
would  contain  above  double  the  number  of  Ihips  pr<^pabd  to  be  held  in  the  new  London  docks, 
which  have  been  long  in  agitadon ;  at  the  fame  time  that  it  would  be  near  the  centre  of 
commerce,  more  than  twice  as  ehoap  in  time  an4  niouey,  and  require  no  houfes  to  be  pulled 
down,  nor  eftablifhed  courfe  of  induftry  f o  be  diftiMrbed. 

The  flope  on  each  fide,  which  nvuft  neceiTarily  be  addcjd  to  diis  ftrudure,  is  propo&d  to  have 
an  incltnadon  anfwering  to  three  inches  in  the  y^d,  and  will  then,  as  Mr.  Dodd  afferts,  ter^ 
minate,  on  the  city  fide,  at  Monument*yard,  ^  on  the  Borough  fide^  near  St  Thoou^'s 
HoTpital.  And  this  may  be  proportionally  diminiflied,  eidier  in  inclinadon,  or  in  lengdiy 
by  making  the  main  arch,  only  60  or  70  feet  high,  which,  it  is  obferved,  will  afford  the  iame 
advantages,  provided  the  ifaipping  ftrtke  dieir  yards  and  tq)m^fts.  The  evident  advantages  of 
this  plan  are  detailed  at  length,  with  confideraUe  a^umadon,  in  thefe  letters;  in  the  fecond  of 
which,  die  fubjed  is  confidercd,  as  to,  i.  PraAicabiiity  with  regard  to  the  ere^on.  %.  Dcc]^ 
ehtng  the  river  above^bridge.  3.  The  creAion  of  quays,  wharfe,  &c.  4.  Facility  of  accomnio^ 
dation  to  the  commerce  of  die  port  of  London^  5^  AjivsAfages  of  commercial  tran&Sionf 
hi  nvers,  beyond  thofe  in  docks,  and,  in  particelar;  iof  diis  plan,  b^rond  %hc  plan  of  the  London 
jdocks  i  and,  6.  The  poiEbility  of  conipleti^  this  undertaking,  without  any  expence  being  laid 
4^^  the  (hipping. 

In'confeqnence  of  this  difplay  and  elucidation  6l  diefubjed,  a  petldon  tos  fotejy  boen  pre;, 

fented 


iji  Pkn  fir  triBing  0  Bridge  at  Lmdtn^  Ufc. 

faiited  to  die  Hottfe  <^  Commons,  in  favour  of  the  plan,  and  die  Ci^  of  London  ditedei 
George  Dance,  e(q.  ardiked  to  ihe  corporation,  to  examine  andr  verify  die  local  circum- 
ftances  relating  to  the  fiune.  By  the  help  of  fome  notes  I  have  taken  from  a  fe&ion  made 
1^  this  architdft,  which  I  have  (ben  at  the  Right  Honourable  Sir  Jofeph  Banks*8»  I  ihall  be 
enabled  to  make  a  few  obfervations. 

From  fome  experiments  made  by  the  Society  for  the  Encouragement  of  Arts,  under  die  di-» 
re£lion  of  their  able  fecretary,  Mr.  Moore,  with  an  appropriate  inffrumenti  for  meafuring  Ae 
rea£tion,  I  upderftand  that  a  horfe,  moving  at  the  rate  of  three  miles  an  hour,  can  only  exert  e 
force  equal  to  70  or  Zolb.  and  from  the  general  eftimate  of  the  work  of  horfes,  deduced  at 
page  466  of  the  fecond  vol.  of  our  Journal,  the  readion  againft  a  commoa  horfe,  moving  at 
the  lame  rate,  will  prove  fomewhat  left  than  (>olb»*  and  the  half  of  this,  namely  yM*  ^iU  ^ura 
out  to  be  die  fteady  force  exerted  by  a  horfe  in  a  poft-chaife,  or  carriage,  which  in  Londoo 
is  feldom  driven  quicker  than  at  the  rate  of  about  fix  miles  and  a  half  an  hour ;  though,  on  tfaa 
roads  near  London,  they  go  at  the  rate  of  eight,  and  fomedmes  near  nine  miles  an  hour.  I  think 
it  likely  that  there  might  be  fomewhat  of  temporary  eflFurt  in  die  dedudion  of  Mr.  Moore^ 
and  that  'joBf.  may  be  a  good  eftimate  fir  theftout  cart-horles  in  London;  and,  from  various 
circumftances,  particularly  the  over-rated  deduf^ions  of  ieveral  refpeSable  authors,  we  may 
infer  that  the  animal  can  donUe  his  efforts  for  a  (hort  dme,  ftich  as  ten  minutes,  without  re- 
ceiving any  injury  from  the  exertion.  Thefe  fpeculadons  are  notoniy  of  general  utility^  but  are 
particularly  applicable  to  the  fubjed  before  us.    If  the  dope  of  Mr»  Dodd^s  bridge  ihould  ^ 
be  fo  confiderable  as  to  require  additional  horfes  to  fiirmoant  it, — or  if  the  length  of  the  inclined 
plane,  required  to  afford  an  eafy  afcent,  fhould  be  fuch  as  to  exceed  every  rtafonable  computa* 
tion,  with  regard  to  the  expences  of  conftruflion,  and  the  purchafe  of  lands,— either  of  thefe 
refiilts  would  afford  the  moft  ferrous  objedions  to  the  plan  itfelf*    Mr«^  Dance's  fiirvey  appears 
to  have  thefe  particulars  in  view. 

^  In  his  drawing,  the  new  bridge  is  traced  ico  feet  high  {n  die  dear,  ahsve  bigb  waUr^  and  a 
thicknefs  of  rather  more  than  ten  feet  is  allowed  between  the  interior  curve  of  the  crown  of 
the  arch,  and  the  pavement.     Hence  die  inclination  of  a  line  drawn  from  Monument-yard  to 
the  higheft  part  of  the  bridge  pavement  gives  3,9  inches  rife  per  yard,  or  very  nearly  one 
ninth.     If  we  fuppofe,  therefore,  an  horfe  to  draw  half  a  ton  up  diis  Hope,  the  weight  will 
re-a&  with  about  120  pounds,  and  from  the  length  of  the  line  of  inclination,,  it  appears  that 
the  horfe  would  have  this  pull  to  make  for  about  duiee  minutes.     But  I  mud  not  overlook 
that  Mr.  Dance's  arch  is  taken  from  the  top  of  high  water,  whereas,  that  of  the  projeftor  is 
ftated,  in  two  places  of  his  pamphlet,  to  be  taken  from  low-water  line ;  which  makes  a  differ^* 
ence  (as  I  gather  from  the  two  lines  in  Mr.  Dance's  fe£kion)  of  22  feet,  or  more  than  one>» 
fifth  in  the  whole  rea£Hon,  and  reduces  it  to  S5  pounds,  or  very  litde  more  than  Mr.  Moore's 
horfes  at  plough  did  fteadily  ove|[Conie.     If  this  reafoning  be  well  founded,  it  will  confequendy 
fidlow,  that  the  fiidden  afcent  of  Mr.  Dodd's  flope  will  not  occafion  any  inconvenience^  or 

♦  That  is  to  fay,  the  horfe  raifes  (or  moves  againft  a  re-a6^ion  of)  %i  hogiheads  of  water,  or  i375^b.^  (at  thfe 
pttc  of  or)  through  ten  feet  in  a  minute.  But  three  milts  per  hour,  give  the  rate  of  ^64  feet  per  mmutt-} 
whence  264 :  10 : :  1375  :  io^ 

render 


London  Bridgi  ImprwemiHt.^^Strdntlan.  ^[37 

tender  it  necel!ary  to  take  his  fmaller  arch,  which  would  dicninilh  it  by  one-third  more,  and 
bring  the  refiftance  within  the  lowcft  eftinuite  of  re-a£tion  given  in  the  foregoing  paragrs^h. 
Mr.  Dance  has  (hewn  in  his  furvey,  that  the  mean  inclination  of  Holbom-hill,  from  Field- 
lane  to  Bartlett's-buildings,  gives  a  rife  of  2)06  per  yard,  and  that  a  dope  of  this  kind  would 
reach  about  half  way  between  Lombard-ftreet  and  Eaftcheap ;  the  latter  of  which  ftreets  would 
be  nearly  half  fliut  in,  while Thames-ftreet  would  be  entirely  furmouiite J,  or  covered  up  ; — that 
the  inclination  of  Ludgate-hill  from  the  obclifk  in  Bridge-ftrcet  to  the  rails  in  St.  Paul's  Church.- 
yard  gives  a  rife  of  0,96  inches  per  yard,  and  that  a  flope  of  this  kind  would  reach  beyond 
Tbread-needle-ftreet  on  the  city  fide,  paffing  at  double  the  height  of  the  houfcs  on  the  fouth* 
fide  of  Thames-ftreet  \  compieatly  covering  Eaftcheap  ;  intercepting  tlie  fecond-fioor  windows 
at  Lombard-ftreet ;  croiSng  Cornhill  at  the  height  of  twelve  feet,  or  above  the  tops  of  the 
(hop-windows ;  and  nearly  four  feet  high  at  the  end  of  Thread-needle-ftreet.  The  lame 
flope  on  the  Borough  fide  would  reach  completely  through  that  town,  and  meet  the  ground 
on  the  road  beyond  the  ftones'  end :  the  whole  length  of  both  ilopes  being  above  one  mile  and  a 
quarter.  It  feems  unneceflary  to  enter  into  the  confequences  deducible  from  thefe  fadh,  or  to 
obferve,  how  much  the  length  of  thefe  inclined  roads  would  be  diminiflied  by  redifying  die 
drawing  with  regard  to  the  water-line,  or  by  adopting  the  loweft  of  Mr.  Dodd's  arches ;  the 
latter  of  which  would  make  a  difference  of  nearly  two  to  one.  For  if  the  extreme  declivity, 
or  fnorteft  inclined  plane,  in  Mr.  Dance's  plan  can  be  eafily  furmounted  by  a  loaded  horfe, 
for  the  time  required  to  pafs  over  its  length,  it  would  follow,  of  courfe,  that  (peculations  ref- 
pe^ing  other  planes  will  be  fcarcely  applicable  to  the  fubjedl  *. 


I  have  received  a  letter  from  the  Rev.  Mr.  Richardfon,  of  Bath,  inclofing  the  fecond  letter 
ftatea  by  Dr.  Gibbes  (fee  p.  96  of  our  laft  number}  to  be  ftrongly  in  his  favour;  and  alfo 
a  letter  from  Dr.  Beddoes,  on  the  (ame  fubjed  ;  which  letters  I  hope  will  terminate  the 
difcuiSon.  Mr.  Richardfon  (April  20)  quotes  an  aflertion  of  Mr.  Notcutt,  made  in  conver- 
fation  fince  the  difpute,  that  he  did  not  know  what  the  fpecimen  was,  but  conje£tured  it  might 
be  fulphate  of  ftrontian;  at  the  fame  time  that  Mr.  N.  informed  Mr.  R.  that  he  did  not  yet 
know  its  compofition,  as  neither  he,  nor  Mr.  Clayfield  had  analyfed  it.  The  fubfequent  part 
of  i^.  R.*s  letter,  contains  general  inference  and  obfervation  of  that  kind,  which,  in  fele^ihg 
the  mete  fadls,  I  have  avoided  relating ;  and  a  requeft  that  Dr.  Beddoes  would  tranfmit  to 
me  the  fads  contained  in  his  letter.  YroSx  Dr.  B.'s  letter,  I  find  that  he  did  not  think  it  in- 
cumbent  on  him  to  publifli  Mr.  R.'s  report  of  Mr.  Notcutt's  teftimony,  becaufe  he  was  in 
poileffion  of  the  teftimony  itfelf^  and  be  therefore  returned  this  fecond  letter  in  time,  with  an 
invitation  to  Mr.  R.  to  (end  it  to  me,  if  he,  or  Dr.  G.  thought  it  to  the  purpofe.  With  re- 
gard to  the  general  fubjefl.  Dr.  B.  afles  me,  whether  I  ought  not  to  diftingutfh  between  the 

^  Since  the  tbore  was  compofed,  I  have  been  informed  that  in  Mr.  Dodd't  plan,  firft  pub'Hhed  in  a 
6Bgle  Iheet,  the  main  arth  was  propofed  to  be  elevated  one  hundred  £eet  above  high  water,  and  that  this 
wsa  the  plan  fubmitccd  to  Mr.  Dance.  ' 

Vol.  Ill—- Junb  1799*  ^p  v      tMmitf 


138  9ik»  in  DuHk  Rtfjh^  l^c. 

noCofiety  of  a  difcoverj,  and  of  the  dilcowiter  i  Wbedier  (be  name  of  die  titter  eould  be  laid  t» 
be  before  the  public  ?  Whether  I,  or  one  in  many  hundreds,  even  of  my  Englifb  readers^ 
knew  it  i  And  whether  Dr.  G/s  paper  will  not  make  him  pafsfor  the  difcoverer  abroad^  till  the 
iucceeding  numbers  of  the  Journal  fliall  correft  this  error  i  And  he  adds,  that  diere  can  be  no 
doubt  of  the  iimilarity  of  die  Sodbury  mineral,  to  fome  varieties  of  that  nearer  Briftol.  Mr. 
Clayfield  fufpeds  the  Red-land,  Ham-green,  and  Sodbury  ftrontian  to  come  from  Ac  &me 
vein* 

With  r^ard  to  the  queftions,  there  is  but  one  which  feems  to  call  on  me  for  an  anftrer ; 
and  to  thU  I  reply,  that  I  knew  nodiing  of  Mr.  Clayfield,  and  ihould  probably  have  mentioned 
him  in  a  note,  or  modifkation  of  the  tide  at  page  535,  of  die  fecond  volume  of  this  Journal^ 
if  I  had.  ^ 

Extras  §f  a   Litter  from  Mr.  H.  Davy. 

*^  When  I  mentioned  to  Mr.  CUyfield  theexiftence  of  (ilex  in  the  epidermis  of  vegetaUes^he 
itquefted  me  to  examine  the  equifetum  hyemale,  or  Dutch  ruib,  vkd  in  manufafiories  fojr 
polifliing  brafs,  &c.  A  (hort  time  after,  Mr.  Notcutt  informed  me  that  he  had  fucceeded  in 
obtaining  a  globule  of  glafs  from  it  by  the  blow-pipe.  I  have  examined  this  plant,  and  find 
that  the  epidermis  of  it  is  almofl:  wholly  compoied  of  filex,  which  is  reticularly  di^iofbd  like 
that  of  the  bonnet  cane,  or  calamus  rotang* 

<^  Since  my  laft  letter  to  you,  I  have  feen  a  paper  of  the  ingenious  Vauquelin,tn  the  88  No^ 
of  Annales  dc  Chimic,  On  the  Excrement  of  Fowls  comparedwith  their  Nourifimiknt ;  withfime 
Obfervations  an  the  Formation  of  the  Egg.  He  found  in  the  afhes  of  the  oat-grain,  filex  and 
phofphate  of  lime.  I  have  not  yet  had  time  to  exaunine  any  grains  or  feeds,  but  it  is  more  than 
probable  that  the  filex  exifls  in  the  epidermis  of  the  oat-grflio,  and  not  in  the  fiurina.  The 
huflcs  of  wheat  and  barley,  as  well  as  the  feeds  of  graflib$»  and  hard  (hells  and  capfules.  of 
fruit,  will,  I  have  no  doubt,  be  found  to  contain  flint*" 


The  following  printed  addre(s  was  tranfmitted  to  me  by  the  penny«poftt  under  comr  of  ir 
letter  firom  Mr.  Pepys,  jun.  to  acqusdnt  me  that  the  Society  had  order^ed  it  to  be  &nt  to  the 
Scientific  Journals.  In  return,  I  (ent  aletter.requefling  information  concerning  tbeconftii*. 
totion  and  funds  of  the  Society,  particularly  with  a  view  to  inform '  the  public:  of  the 
regulations  under  which  they  might  contribute  to^  the  defirable  objedl  held  forth,  as  well. 
as  of  the  degree  of  confidence  this  body  might  be  entitled  to.  To  tbeie  inquiries  I  received 
only  a  verbal,  anfvrer,  that,  the  Society,  ia  not  yet  org^zqd>,  and  that  a&  profpe^ui^  will- 
be  fentto  me  z»  (bop  as  publifhed. 

Britijh  JliCmrabgiexl  Stciety^. 

The  benefits  which  have  refulted  to  our  manu&Aures,  don^eftic  economy,  and  convenience, 
from  the  great  progrefi^  made  in  othe;i:  branches  of  fcience,  have,  for  a  confiderable  dme,  caUedj| 
for  die  eftablifhment  of  a  Society  whofe  attention  (hould.hc  diredcd  to  the  aoaIy(isand. 
of  our  native  ores  and  nuperals. 

The 


The  principal  obftade  that  hindefred  our  mineralogmal  treafuret^  ftdnl  Mug  d^Ioied  ha*, 
in  foaiemeafure)  been  happily  removed  by  the  scdvances  that  have  beat  made  in  chemical 
knowledge ;  and  there  is  now  every  reafon  to  hope  that,  at  no  rery  diftant  period,  by  Ae  gradual 
removal  of  other  impediments,  an  accurate  knowledge  will  be  obtained  of  the  compofitioiiy 
nature  and  properties,  not  only  of  fuch  minerals  as  are  generally  found  in  cabinets,  but  of  the- 
various  hitherto  neglefted  ftrata  of  the  different  parts  of  diis  kingdom; 

There  are,  no  doubt,  in  many  of  our  mines,  other  vahiable  metals  and  minerals  (at  prefent 
imported  from  abroad)  befides  thofe  they  are  worked  for ;  which  want  of  chemical  knowledge 
refpeAing  the  compound  ftate  of  fuch  produSions  have  caufcd  to  be  hitherto  entirely  neglednd. 
Nor  indeed  could  it  be  expeded  that  the  miner,  whole  bufinefs  is  to  produce  a  given  quantity 
of  a  known  metal  in  a  ihort  time,  fbould  fo  far  wander  from  his  track  as  to  attempt  to 
examine  what  he  has  always  been  taught  to  confider  as  wafte.  When  he  meets  widi  any 
odier  fubftance  than  the  one  he  is  in  queft  of,  it  excites  no  attention,  and  in  many  inftances 
is  turned  out  of  the  mine,  and  fcattered  like  rubbifh  X»  repair  the  roads. 

To  affift  in  preventing  a  wafte  of  the  bounties  afforded  by  Providence  to  this  country, 
The  British  Mineralooical  Society  has  been  inftituted  ;  but  the  landholders  and 
.  proprietors  of  mines  can  alone  overcome  the  obftades  which  arife  from  the  prejudices  of  the 
minerSyby  caufing  them  to  produce  famples  of  die  various  ftrata  they  pa(s  through,  and  by 
pving  them  premiums  for  every  new  fubftance  of  ^ich  they  may^  be  able  to  produce 
l^cimens.-«The  country  will  be  benefited  exadiy  in  the  proportion  that  luch  a  pra£Uce 
fliall  become  generals 

The  Britifli  Mineralogical  Society  will  analyfe,  frte  rf  exfencey  package  and  carriage 
excepted,  for  the  proprietors  of  mines  or  landed  eftates,  whatever  fubftance  they  may  meet 
with  in  fufficient  quantiiy  to  render  a  knowledge  of  the  component  parts  a  defirable  obje£l» 
In  return,  the  Society  expeds  that  fingular  or  curious  fpecimens  of  the  mineral  produdions, 
irtiich  may  be  met  with  in  working  the  Britifh  mines,  will  be  (ent  for  the  improvement  of  the  ^ 
Society's  Cabinet,  which  will  thus  in  time  become  a  national  ornament. 

It  muft  be  obvious,  that,  in  purfuits  of  this  nature,  a  Society  pofteftes  many  advantages  over 
an  tndividuai  \.  for,  in  every,  c^fe  where  the  component  parts  of  a  mineral  are  very  intricate,,  the 
knowledge  and  experience  of  all  the  members  can  be  concentrated  for  the  analyfis. 

Wiito  the  analySs  of  any  mineral  fetit  for  examinination  is  completed,  the  refult,  witb. 
Wl  account  of  the  methods  employed,  will   be  fent  to  the   proprietor  of  the  fpecimen; 
wA  if  it  (hallt  contain  any  new  fubftance,  the  probable  u£s  to  which  it  may  be  applied  will 
Ito  fuggefted^ 

Sddl  IS  die  outline  of  the  Plan  of  the  Society^  whichy  having  nothing  mercenary  in  view, 
encourages  its  members  toexped-tbat  their  labours  for  the  mineralogical  improvement  of  the 
Britilh  natiiMi  wiH  be 'feoondedy^iot  only  by:  thofe  who  have  aaimmediate  intereft  in  obtaining; 
an  accurate  knowledge  of  the  nature  and  properties  of  the  various  mineral  produ&ions  of 
Ihetr  eftates,  but  by  every  individual  who  has  the  profperity  of  his  country  at  heart. 

Specimens  ient  for  analyfis  are  requefted  to  be  packed  up  in  fuch  a  manner  as  to  prevent,  as 
■mcfa  as  poffible,  dieir  being  nibbed  or  fretted  by  the  carriage  \  as  the  external  ftrudure  and 

fihaia^ier 


ij^o  Society  far  analyxtng  Afimralsr  Wr. 

character  of  minerals  4)ften  aflift  in  leading  to  z  knowledge  of  their  compofition.  It  is  alfo 
fequefted  that  an  account  be  fent  of  the  circumftances  conn^ed  with  the  fpccimen,  as  the 
dq)th  below  the  furface  of  the  earth,  and  the  nature  and  thicknefs  of  the  ftratum  in  which 
it  i6  found,  and  alfo  of  the  incumbent  and  fubcumbent  ilrata,  &c.  and,  where  ncceflary, 
fpecimcns  of  thefe  with  their  provincial  technical  names. — Addrefs  the  package  (carriage  paid) 
to  the  Society's  Secretary,  Mr.  W.  H.  Pepys^  junior,  No.  24,  Poultry,  London. 

By  Order  of  the  Society. 

\V.  H.  VLVVS,}un.Sfcreta^: 


A  Praftical  IntroduSion  to  Spherics  and  Naotical  Aftronomy,  being  an  attempt  to  fimplify 
thofc  ufeful  Sciences, — containing,  among  other  original  Matter,  the  Difcovery  of  a  Prcgedion 
for  clearing  the  Lunar  Difhinces  in  order  to  find  the  Longitude  at  Sea  ;  with  a  new 
Method  of  calculating  that  important  Problenu  By  P.  Kelly,  Mafter  of  Fin(bury»fquare 
Academy,  London.    Johnfon  and  Robinfons.    Price  6s.  p.  210.  pi.  17. 

This  work  is  divided  into  two  parts  ;  the  firft  contains  the  principles  of  ft:reographic  prqgec-' 
tion,  exemplified  by  numerous  figures  drawn  upon  a  large  fcale ;  thefe  are  followed  by  right* 
angled  and  oblique  fpheric  trigonometry,  in  Which  all  the  problems  are  fcrfved  both  by  prcjedtda 
and  calculation :  this  part  concludes  with  improved  folutions  of  certain  cafes  of  fpheric  trian^piL 

The  fecond  part  treats  of  aftromony,  particularly  thofc  parts  which  are  ufeful  at  fea  ;  fudi 
as  finding  azimuths,  amplitudes,  time,  latitude,  and  longitude.  Thefe  problems  are  folved  hj 
the  globes,  and  likewife  by  projeftion  and  calculation. 

The  method  of  finding  the  longitude  by  lunar  obfcrvation  is  here  explained  at  fome  lengtiiy 
in  a  dear  and  elementary  manner.  The  principles  of  this  problem  are  explained  by  ftereogra- 
phic  projections,  whence  rules  are  deduced  for  eftimating  the  true  diftance  beforehand. 

A  new  projedlion  here  given  for  clearing  the  diftancc  from  parallax  and  refradion,  is 
performed  by  drawing  four  right  lines  from  the  plan  fcale.  The  author  does  not  infift  upon 
this  method  as  affording  a  perfed  folution  of  the  problem,  but  he  obfcrves  that  it  i^ill  be 
found  fufficiently  exact  for  the  general  purpofcs  of  navigation,  and  where  perfeA  cotre&iels,  is 
j'cquired,  it  will  even  be  found  ufeful  as  a  guide  or  check  to  calculation. 

The  new  method  given  for  working  the  lunar  obfervation,  confifts  in  the  regular  folutioo  of ^ 
two  fpherical  triangles,  and  taking  the  zenith  diilances  inflead  of  the  altitudes,  by  which  tb? 
operation  is  performed  by  fines  only  :  this  is  certainly  an  advantage,  efpecially  to  learners,  who 
are  apt  to  confound  fines  with  cofinis,  &c.  but  how.  ver  fimple  and  accurate  this  method  may 
be,  it  cannot  be  conveniently  applied  except  by  fuch  as  are  in  poflfeflion  of  Tayior't 
Logarithms^  or  fome  other  tables  which  readily  afford  portions  of  the  quadrant  to  feconds* 

The  figures  throughout  this  work  are  on  a  large  fcale,  vnd  appear  to  be  very  contBU 


i. 

'a 


c 


V 


*♦ 


mm^mi 


TUJWH  »«UM»ATIu«t« 


MMiW 


1 


^     k 


•1       <• 


.('..•^•••"•"'l 


/3aAffme^ti^  x^//i/a^ntrme/Uc  ff^^  m^wM.i 


Fip.Z. 


FIg.S 


Fig   4 


Mf.6. 


142  Unufual  Appearances  by  terrejirial  RtfraRion. 

wyi  not  alter  the  poHtion  of  their  parts,  in  re(pe£l  to  the  horizon ;  that  iS)  the  image  of  the 
higheft  part  of  the  objeft  will  be  uppermoft,  and  the  image  of  the  loweft  part  will  be  under* 
moft.  The  figures,  however,  of  the  fun  and  moon,  when  near  the  horizon,  will  fuffer  a 
change  in  confcquence  of  the  refraflion  of  the  under  limb  being  greater  than  that  of  the 
upper,  from  which  they  affume  an  eliptical  form ;  the  minor  axis  of  which  is  perpendicular 
to  the  horizon,  and  the  mtijor  axis  parallel  to  it.  But  a  perpendicular  obje£ly  fituated  upon 
the  furface  of  the  earth,  will  not  have  its  length  altered  by  refra6lion  ;  the  refraftion  of  the 
bottom  being  the  fame  as  that  of  the  top*.  Thefe  are  the  effefts  which  are  produced  upon 
bodies  at,  or  near,  the  horizon,  in  the  common  ftate  of  the  atmofphere,  by  what  I  fliall  call 
the  ufual  refraction. 

But  befides  the  ufual  refraftion  which  affefls  the  rays  of  light,  the  atmofphere  over  the  fea  15 
fomctimes  found  to  be  in  a  ftate  which  refradls  the  rays  in  fuch  a  manner,  as  to  produce  other 
images  of  the  objecft,  which  we  will  call  an  effe£l  from  an  unufual  refraftion.  In  the  Phil. 
Tranf.  for  1797,  Mr.  Huddart  has  defcribed  fome  efFefts  of  this  kind,  which  he  has  accounted 
for,  by  fuppofmg,  that  from  the*evaporationof  the  water,  the  refraftive  power  of  the  air  is  not 
greateft  at  the  furface  of  the  fea,  but  at  fome  diftance  above  it;  and  this  will  folve  in  a  very 
fatisfaftory  manner,  all  the  phenomena  which  he  has  obferved  :  but  efFeSs  very  different  fron^ 
thofe  defcribed  by  Mr.  Huddart,  are  fometimes  foimd  to  take  place.  Thefe  I  had  an  oppor- 
tunity of  obferving  at  Ramfgate,  laft  Summer,  oa  Auguft  the  firft,  from  about  half  an  hour, 
after  four  o'clock  in  the  afternoon,  till  between  feven  and  eight.  The  day  had  been  extremely 
hot,  and  the  evening  was  very  fultry;  the  fky  was  clear,  with  a  very  few  flynig  clouds*  I 
(hall  defcribe  the  phenomena  as  I  obferved  them  with  a  terreftrial  telefcope,  which  magni- 
fied between  thirty  and  forty  times ;  they  were  vifible,  however,  to  the  naked  eye.  The 
height  of  the  eye  above  the  furface  of  the  water,  at  which  moft  of  the  obfervations  were  madq^ 
was  about  twenty-five  feet;  fome  of  them,  however,  were  made  at  about  eighty  feet  from  the 
furface;  and  it  did  not  appear  that  any  of  the  phenomena  were  altered,  from  varying  the  height 
of  the  eye,  the  general  efFcft  remaining  the  fame. 

The  firft  unufual  appearance  which  I  obferved,  was  that  which  is  reprefented  in  Plate  Vlf. 
tg.  I.  Diredmg  my  telcfcope  at  random,  to  examine  any  objeds  which  might  happen  to 
be  in  view,  I  faw  the  top  of  the  mafts  of  a  (hip.  A,  above  the  horizon,  x  y,  of  the  fea,  as  ihewn 
in  the  figure.  At  the  fame  time  alfo,  I  difcovered  in  the  field  of  view  two  complete  images, 
B,  C,  of  the  fliip  in  the  air,  vertical  to  the  (hip  itfelf.  B  being  inverted,  and  C  eredl,  having 
their  h ulks  j oined.  The  phenomenon  was  fo  ftrange,  that  I  requefted  a  perfon  prefent  to  look  into 
the  telefcope,  and  examine  what  was  to  be  feen  in  it,  who  immediately  defcribed  the  two 
images  as  obferved  by  myfelf ;  indeed  they  were  (b  perfeft,  that  it  was  impoffiUe  we  could 
differ  in  our  defcription.  Upon  this,  I  immediately  took  a  drawing  of  the  relative  magnitudes, 
and  diftances  of  the  ftiip,  and  its  images,  which  at  that  time  were  as  reprefented  in  the  figure^ 
as  near  as  it  was  poffible  for  the  eye  to  judge  ;  and  it  was  very  eafy  to  eftimate  them  to-  a  very 
confide  cable  degree  of  accuracy.    As  the  fhip  was  receding  from  the  (hore,  lefs  and  lefs  of  its 


See  my  Complete  Syfti^m  of  Aftronomy,.  art»  194* 


mafts^ 


Unufual  appearances  by  Urrejrial  RefraStion^  m 

mafts  became  vifible;  and  continuing  my  obfervations,  in  order  to  difcover  whether  any  or 
what  variations  might  take  place^  I  found,  that  as  the  (hip  defcended,  the  images,  B,  C,  afcend* 
ed  y  but  as  the  (hip  did  not  fmlc  below  the  horizon,  1  had  not  an  opportunity  of  obferviog  at 
what  time,  and  in  what  order  the  image  would  have  vani(bed,  if  the  (hip  had  fo  difappeared.  # 

Being  defirous  of  feeing  whether  the  fame  efFedt  was  produced  upon  the  other  (hips  which 
were  vifible,  I  dircdlcd  my  telefcope  to  another  (hip,  A  ffig-  2),  whofe  hulk  was  juft  in  the 
horizon,  x  y\  when  I  obferved  a  complete  inverted  image,  B,  the  main-maft  of  which  juft 
touched  that  of  the  (hip  itfelf.  In  this  cafe,  there  was  no  fecond  image  as  before.  .  The  (hip, 
A,  moving  upon  the  horizon,  B  continued  to  move  with  it  without  any  variation  in  its  ap- 
pearance* 

The  next  (hip  which  I  direfted  my  telefcope  to,  was  fo  far  on  the  other  fide  of  the  horizon, 
yy,  as  juft  to  prevent  its  hulk  from  being  feen,  as  is  reprefentcd  by  A  (fig.  3).  And  here  I 
obferved  only  an  inverfed  image  of  part  of  the  (hip ;  the  iipage,y,  of  the  topfaii,  with  the  maft  ^ 

joining  that  of  the  (hip>  the  image  x  of  the  top,  a  of  the  other  maft,  and  the  image  z  of  the  end  c 
pf  the  bowfprit  only  appearing  at  that  time.  Thefe  images  would  fuddenly  appear  and  difap- 
pear  very  quickly  after  each  other ;  firft  appearing  below,  and  running  up  very  rapidly,  (hewing 
more  and  lefs  of  the  mafts  at  different  times  as  they  broke  out ;  refembling  in  the  fwiftnefs  of 
their  breaking  out,  the  fliooting  out  of  a  beam  of  the  aurora  borealis.  As  the  (hip  was 
defcending  on  the  other  fide  the  horizon,  I  continued  my  obfervations  upon  it,  in  order  to  dif- 
cover what  changes  might  take  place ;  when  I  found,  that  as  it  continued  to  dcfcend  more  of  the 
image  gradually  appeared,  till  at  laft  the  image  of  the  whole  (hip  was  completed,  with  theif 
main-mafts  touching  each  other;  and  upon  the  fhip  defcending  lower,  the  image  and  the  (hip 
feparated ;  but  I  obferved  no  fecond  image  as  in  the  iirft  cafe :  a  fecond  image,  however^ 
isight  probably  have  appeared  if  the  (hip  had  continued  to  defcend. 

Upon  moving  my  telefcope  along  the  horizon,  in  order  to  examine  any  other  (hips  which 
might  be  in  fight,  I  obferved,  juft  at  the  horizon,  x  y  (fig.  4),  the  top,  a^  of  the  maft  of  a  (hip; 
and  here  an  eflfeft  was  obferved  which  had  not  been  difcovered ;  for  there  was  an  inverted 
image,  B,  vertical  to,  ^,  an  erc6t  image,  C,  both  of  them  very  perfedl  and  well  defined ;  and 
an  image,  v  w,  of  the  fea  between  them,  the  water  appearing  very  diftinftly.  As  the  (hip  was 
coming  up  towards  the  horizon,  I  continued  to  obfervc  it,  in  order  to  difcover  the  variations 
which  might  follow,  and  found  that,  as  the  (hip  approached  the  horizon,  the  image  C 
gradually  difappeared,  and  at  laft  it  vaniihed ;  and  after  that,  the  image  v  w  of  the  fea  difap- 
peared ;  and  during  this  time  the  image  B  defcended;  but  the  (hip  did  not  rife  fo  near  to  the 
horizon  as  to  bring  the  main-mafts  together.  Had  I  direfled  my  telefcope  to  the  fame  poinjt  • 
of  the  horizon  a  little  fooner,  I  (hould  have  feen  the  two  images  before  the  (hip  itfelf  was 
vifible;  in  faft,  the  images  were  vifible  when  the  whole  (hip  was  acSlually  below  the  horizon; 
for  from  the  very  fmall  part  of  the  maft  which  was  at  firft  vifible,  that  part  muft  then  havp  been 
below  the  horizon,  and  appeared  above  it  by  the  ufual  refraftion;  the  altitude  of  a  above  the 
horizon  having  then  been  much  lefs  than  the  increafc  of  altiljide  which  arifes  from  the  common 
horizontal  r^fradions.    The  difcovery  of  fhips  in  this  manner,  might  in  fome  cafes  be  of  great 

U  2  importance; 


f  44  UHcommen  EfftEls  of  Rtfraflm  ufm 

importance ;  and  on  fuch  occafions,  it  might  be  worth  while  to  appoint  proper  perfbns  to  make 
obfervations  for  that  purpofe. 

The  cliffs  of  Calais  being  very  vifible,  I  direfted  my  telefcope  towards  them,  in  order  to  ex- 
amine whether  there  were  any  thing  unufual  in  their  appearance;  when  I  obferved  an  image  of 
the  cliffs  above  the  cliffs  thcmfelves,  together  with  an  image  of  the  fea  feparating  them,  as  is 
reprcfented  in  fig.  5,  in  which  jry  reprefents  the  horizon  of  the  fea,  A  B  the  cliffs,  a  h  their 
image,  and  v  lu  the  image  of  the  fea  between  them ;  the  depth  of  a  b  was  much  lefe  than  that 
of  A  B.  It  is  probable,  however,  that  v  w  might  not  be  the  image  of  the  fea  immediately  ad-« 
joining  to  the  cliffs,  but  a  partial  elevation  of  the  fea  at  fome  diftance  from  them  ;  and  that 
die  image  v  w  might  intercept  fome  part  of  the  image  a  by  which  would  otherwife  have  beea 
vifible  i  we  muft  not,  therefore,  conclude  diat  the  image  a  b^  fo  fiir  as  it  appeared,  was  lefs  than 
the  correfponding  part  of  the  objeft.     From  the  memorandums  which  I  made  at  the  time  of 
obfervation,  1  do  not  find  that  I  examined  the  appearance  of  the  cliff,   A  B,  and  its  images 
a  bf  which  had  there,  at  that  time,  been  any  ftriking  marks  in  diem,  would  have  determined 
whether  the  objed  and  its  image  were  of  the  fame  magnitude.     The  image  a  b  was,  however^ 
ere£t ;  the  boundaries  on  the  top  of  A  B  and  a  b  agreeing  together.      Having  examined  this 
for  fome  timc^  and  taken  a  drawing  of  the  appearance,  during  which  I  could  difoovcr  no 
variation,  I  dire£ied  my  telefcope  to  odier  objedls;  and  upon  turning  it  again  to  the  fame 
cliffs,  after  the  fpace  of  about  fix  or  feven  minutes,  the  images  a  b  and  v  of  were  vanished: 
but  examining  them  again  foon  after,  the  images  were  again  vifible,  and  in  every  xtfytBt  tfat 
iame  as  they  appeared  before.     A  (hort  time  after  they  di&ppeared,  and  did  not  appear  any 
more.        '  * 

Soon  after  the  above  appearances,  I  obferved  a  (hip,  C,  with  the  hulk  below  the  horizon,  xy^ 
paffing  by  the  fame  cliffs,  A  B ;  an  inverted  image,  D,  of  which  appeared  againft  the  cliffy 
as  rcprefented  in  fig.  6.  The  {hip  was  in  motion,  and  remained  at  the  lame  diftance  on  die 
other  fide  of  the  horizon.  I  continued  my  obfervations  upon  it^  till  it  had  paffed  the  cliffs  for 
a  confiderable  diftance,  but  there  was  no  change  of  appearance.  The  cliffs  were  illuminated 
by  the  fun,  and  appeared  very  diftindly ;  but  there  was  no  image  above,  as  in  the  laft  cafe. 

Continuing  to  obierve  the  fame  cliffs,  A  B,  fig.  7,  I  foon  after  difcovered  two  partial  ele- 
vations, m  Tty  of  the  fea,  by  the  unufual  refraSion;  they  changed  their  figures  a  litde,  and 
difappcared  in  the  place  where  they  firft  appeared,  and  were  equally  diftin£t  in  every  part. 

About  this  time,  I  difcovered  a  very  thick  fog  coming  upon  the  horizon  froni  the  other  fide, 
rolling  upon  it  with  a  prodigious  velocity,  curling  as  it  went  along,  like  volumes  of  fmoke 
ibmetimes  out  of  a  chinrmey.  This  appeared  feveral  times :  I  conclude,  therefore,  that  there 
was  a  confiderable  fog  on  the  other  fide  of  the  horizon. 

The  laft  phenomenon  which  I  obferved,  was  that  which  is  reprefented  in  fig.  8,  where  x  y 
leprefents  the  horizon,  a  b  two  partial  elevations  of  the  fea  meeting  at  r,  and  continued  to  4% 
/,  another  partial  elevation  of  the  fea,  of  which  kind  I  obferved  feveral,  fome  of  which  moved 
parallel  to  the  horizon  with  a  v&ry  great  velocity.  I  conjedure,  therefore,  that  thefe  ap« 
pearances  were,  in  part  at  leaft,  caufed  by  the  fog  on  the  other  fide  the  horizon  \  for  though  I 

did 


Ji/lant  Ohjiffs  at  Sia.  t^S 

did  not  at  the  lame  time  fee  the  motion  of  thefe  images,  and  Aat  of  the  fog,  yet  from  memory, 
I  judged  the  motions  to  be  equal;  and  they  were  alfo  in  the  fame  diredlion.  A  fog,  which  by 
producing  an  unufual  refradlion,  might  form  thefe  images,  would,  by  its  motion,  produce  4 
correfponding  motion  of  the  images. 

I  have  here  defcribed  all  the  different  phenomena  which  I  obferved  from  the   unufual  re- 
fraftion,  of  moft  of  which  I  faw  a  great  many  inftances.     Every  fhip  which  I  obferved  on  the 
other  fide  of  the  horizon  of  the  fea,  exhibited  phenomena  of  the  kind  here  defcribed,  but  not  in 
the  fame  degree.     Of  two  fhips,  which  in  different  parts  were  equally  funk  below  the  horizon, 
the  inverted  image  of  one  would  but  juft  begin  to  appear,  whilft  that  of  the  other  would  reprefent 
nearly  the  whole  of  the  (hip.  But  this  I  oHferved,  in  general,  that  as  the  (hip  gradually  defcended 
below  the  horizon,  more  of  the  image  gradually  appeared,  and  it  afcended;  and  the  contrary, 
when  the  (hips  were  afcending  upon  the  horizon  in  different  parts,  one  (hip  would  have  a 
complete  inverted  image ;  another  would  have  only  a  partial  image ;]  and  a  third  would  have 
no  image  at  all.    The  images  were  in  general  extremely  well  defined,  and  frequently  appeared 
as  clear  and  (harp  as  the  (hips  tbemfelves,  and  of  the  fame  magnitude.     Of  the  (hips  on  this 
fide  of  the  horizon,  no  phenomena  of  this  kind  appeared ;    there  was  no  fog  upon  our  coafl:, 
and  the  (hips  in  the  Downs,  and  the  South  Foreland,  exhibited  no  uncommon  appearances. 
The  ufual  refraction  at  the  fame  time  was  uncommonly  great,  for  the  tide  was  high,  and  at  the 
very  edge  of  the  water  I  could  fee  the  clifFs  at  Calais   a  very  coniiderable   height  above  the 
horizon ;  whereas  they  are  frequently  not  to  be  feen,  in  clear  weath«r,  from  the  high  lands 
about  the  place.     The  French  coaft  alfo  appeared  both  ways  to  a  much  greater  diftance  than 
I  ever  obferved  it  at  any  other  time,   particularly  towards  the  eaft,  on  which  part  al(b  the 
unufual  refradion  was  the  ftrongeft. 

During  the  remainder  of  my  (lay  at  Ramfgate,  which  was  about  five  weeks,  I  continued 
daily  to  examine  all  the  (hips  in  fight ;  but  I  difcovered  no  phenomena  fimilar  to  thofe  which  I 
have  here  given  a  defcription  of.  The  phenomenon  of  the  (hip,  obferved  by  Mr.  Huddart, 
differed  altogether  from  thofe  above  defcribed,  as  the  inverted  image  which  he  obferved  was^ 
below  the  (hip  itfelf.  An  appearance  of  this  kind  I  obferved  on  Augufl  the  17th,  about  half  an 
hour  after  three  o'clock  in  the  afternoon,  of  which  fig.  9  is  a  reprefentation.  The  real  (hip 
is  reprefentcd  by  A,  and  the  imago  by  B  ;  i  r,  m  Vj  the  hulks ;  i  /,  the  flag ;  and  w  x^  its 
image,  juft  touching  it,  with  the  fea,  x  y,  below.  Between  the  two  hulks,  fome  faint  dark 
fpots,  and  lines  appeared,  but  I  could  not  difcover  what  they  were.  The  reprefentatives  of  the 
veflTel,  at  the  time  of  this  appearance,  was  not  quite  come  up  to  the  horizon ;  and  as  it  ap- 
proached it,  the  image  gradually  diminifhed,  and  totally  difappeared  when  the  (hip  arrived  at  the 
horizon.  • 

It  remains  now,  that  we  enquire  into  the  caufes  which  might  produce  the  very  extracrdl- 
tiary  effe£ts  which  h^ve  been  above  related.  From  the  phenomena,  we  are  immediately  led  to 
the  nature  of  the  path  of  the  rays  of  light  to  produce  them;  and  we  may  conceive  that  the 
air  may  poffibly  be  in  fuch  a  ftate  as  will  account  for  the  unufual  vmSt  which  they  muft  have 

defcribed.. 


14^  Phinomtna  of  unufual  Rt/ra^loft, 

defcrlbcd.  For  let  b  (fig.  lO),  be  the  furfacc  of  the  fca ;  ah  z,  an  objeft ;  E,  the  place  of  th« 
eye ;  arEjbsEy  the  progrefs  of  two  rays  by  the  ufual  refraftion  from  tlie  extreme  parts  of 
the  objeft  to  the  eye;  to  thefe  curves,  draw  the  tangents  E  a\  E  ^',  and  a^  V  will  be  the  image 
of  the  objeS,  as  ufually  formed.  Now  if  we  take  the  cafe  reprefentcd  in  fig.  4.  let  a^  b" 
reprefent  the  inverted  image,  and  d"  b"'  the  ereS  image.  Join  a"  E,  a"  E,  and  b"  E,  h"  E, 
and  thefe  lines  muft  refpeflively  be  the  direftions  of  the  rays  entering  the  eye,  from  a  by  in 
order  to  produce  the  images  a'  b%  and  « "  b'\  hence  thefe  lines  muft  be  tangents  at  E,  to 
the  curves  which  arcdefcribed  by  the  rays  of  light;  let,  therefore,  a  nE^  amEy  b  v  Ey  b  wE^ 
be  the  curves  defcribed.  We  have,  therefore,  to  afEgn  a  caufe  which  may  bring  rays  pafling  above 
the  rays  a  rEj  £  x  E,  to  the  eye  at  E.  Now  if  there  were  no  variation  of  the  refradlive  power 
of  the  air,  a  ray  of  light  palling  through  it  would  defcribe  a  ftraight  line;  therefore  the  curvature 
of  a  ray  of  light  paffing  through  the  atmofphere  depends  upon  the  variation  of  the  refraftive 
powfcr  of  the  air.  If,  therefore,  we  fuppofe  the  air  lying  above  a  r  E  to  vary  quicker  in  its 
refraftive  power  than  the  air  through  which  a  r  E  paffes,  the  curvature  of  a  ray  pro- 
ceeding above  that  of  a  rE  will  be  greater  than  the  curvature  of  a  r  E ;  and  upon  this 
■principle  we  may  conceive  that  a  ray  may  defcribe  the  curve  /?  it  E,  and  in  like  manner,  if 
a  quicker  variation  of  refraflive  power  (hould  take  place  above  the  curve  a  nEy  than  in  that 
curve,  a  third  ray  may  defcribe  the  curve  a  mE.  The  fame  may  be  faid  for  the  rays  b  v  E, 
IwEy  diverging  from  b.  The  alterations  of  the  refraftivc  power  may  arife  partly  from  the 
variations  of  its  denfity,  and  partly  from  the  variations  of  its  moifture;  and  the  paflage  of  the 
rays  through  the  boundary  of  the  fog,  may  there  fufFer  a  very  confiderable  refradion;  for  from 
the  motion  of  the  fog,  and  that  of  the  images  above  mentioned,  I  have  no  doubt  that  the  fog 
was  a  very  confiderable  agent  in  producing-  the  phenomena.  When  all  the  caufes  co-operate, 
I  can  eafily  conceive  that  they  may  produce  the  efFedls  which  I  have  defcribed.  If  the  caufe 
ihould  not  operate  in  the  tra£lof  air  through  which  the  curves  a  nE^  b  vE  pafs,  but  fhould 
operate  in  the  tra£t,  through  which  a  mE^bwE  pafs,  an  eredl  image  which  would  be  vifible, 
but  there  would  be  no  inverted  image;  and  fhould  It  operate  in  the  latter  cafe>  but  not  in  j^e 
former,  there  would  be  only  an  inverted  image. 

As  the  phenomena  are  very  curious  and  extraordinary  in  their  nature,  and  have  not,  that  I 
know  of,  ,bcen  before  obferved,  1  have  thought  proper  to  lay  a  defcription  of  them,  with  all  the 
attending  circumftances,  before  the  Royal  Society.  They  appear  to  be  of  confiderable  im- 
portance ;  as  they  lead  us  to  a  knowledge  of  thofe  changes,  to  which  the  lower  parts  of  the 
atmofphere  are  fometimes  fubjedt.  If  when  thefe  phenomena  appear,  a  vefTel  furnifhed  with  a 
barometer,  thermometer,  and  hygrometer,  below,  and  alfo  at  the  top  of  the  maft,  were  fcnt  out 
to  pafs  below  the  horizon,  and  return  again,  and  an  obferver  at  land,  having  like  inflruments, 
were  to  note,  at  certain  intervals,  the  fituation  and  figure  of  the  images,  it  might  throw  further 
light  upon  this  fubjed,  and  lead  to  ufefiil  difcoveries  refpefting  the  flate  of  the  atmofphere  from 
^conjunction  of  the  caufes  which  a  fFedl  thefe  jnflruments. 

An 


Experlmnts  for  ditumuHing  Standards  of  Weighty  bfc.  14J 

II. 

Jn  Account  of  fome    Endeavours  t§  a/certain  a  Standard  of  freight  and  Meafure.     By  Sir 

George  Shuckburgh  EvELYNy  Bart.  F.R,S.  and  AS. 

(Continued  from  p.  107,  of  the  prefent  volume.) 
(§.  20.)  Experiment  of  the  Cube  of  Brafs  weighed  in  Air. 

Jl  he  cube  was  fufpended  to  the  right  arm  of  the  beam,  by  the  fcale  belonging  to  jt,  and  the 
left  fcale  pan,  with  the  mark  x,  was  hung  at  the  other  end  of  the  beany,  in  which  were  placed 
the  following  weights  ♦,  made  by  E.  Troughton. 

grains. 
viz.  No.  15  of  1 63  84 

14  -  8192  .  "  V 

13  -  4096 

12   -  2048. 

II  -  1024 

9  -  256 

84^82. 

—————  inch. 

The  total  weight  of  the  cube  7  _  ^^^« .  q«  C  the  barom.  being  at  20,0 

in  air  S''^^     l^^^^^-    -    .    ►     at  62^0 

(§•21.}  Exfertnunt  of  the  Weight  of  the  Cylinder  in  Air-^ 

grains. 

No^  15  of  16384 

13  -     4096 
II  -     1024  ^ 

§«"*«•  S3>37 

But  a  counterpoife  of  5S5>02"1  ■           — - 

having  been  ufed,              j  2'>SS7>37 

by     miftake,     in-              \  ,^ 

fteadof     -      -     55^34^  ^                         ' 

Add  this  exce£s    =r         2j68^ 

And  the  total  weight  of  the  cylinder  «      =     "'-^<^°»0S  ^t  a";:^'^  at"  -  *  3^ 

($.23.)  Jhi  Cube  weighed  in  dijiillei  Water. 
Sept.  5.  Put  into  the  left  fcale,  the  coiinterpoiic  for  the  water  f  300  )  gnint. 

fcale  liOo;=      -      -      400,00 

The  cube,  with  its  fcale,  was  then  immerfed  in  the  water. 

■»  Thii  fcaU  contained  atfo  555,0*  graini,  being  the  weight  or  conntcrpoiTe  to  the  fcale  for  the  cube. 

*  I  then 


148  Expirimnii  t9  tffcertaln 

I  then  reftbred  the  equilibrium,  by  putting  into  the  oppofite  or  left*hand 
common  fcale,  Mn  Troughton's  weigh ts.  No*  io«  :;  r. 

(The  barom*  ibuiding  at  29,47  incheSf 
the  therm*  at  6o^|2.) 


But  a  counterpdfe  of  •> 

having  been  taken,  by  miftake^ 


grams. 


grains* 

=  512,00 
200, 

3»7o 

745.70 

42>7S 

,08 
703*03 


(§.23.)  ExpirtMna  rf  tbi  CfUndiT  in  dlfttUei  fFater. 
Sept  5.  The  thermometer  being  at  from  60^2  to  6o%5,  and  the  barometer  29,47  inches, 


s  -  400     •) 

inftead  of  *  442,75  I   =  — 

fo  left  out  -  r=  42,7SJ 

by  i;n-l 

as  ad->    =  4- 


Dedud  the  difference,  which  was 

The  apparent  weight  of  the  cube  in  water  becomes 

Add  the  correftion  *  for  the  lofs  of  weight  of  the  4  wires,  by  i;n- 
merfion  2^  inches  deeper  than  when  the  counterpoife  was 
jutted 

And  the  true  correded  weight  of  the  cube  in  water,  with  60^2  of  heat? 
becomes  .  .  -  -  •  ^ 


Put  into  the  left  fcale  pan,  the  counterpoife  to  the  water-fcale  for  the  cy-  \  3^0 


Under  •  •  •  •  •  •  •# 

The  cylinder,  with  its  water-fcale,  was  inunerfed  in  water.    I  then  reftored  die  equili* 


gnuni. 

300    1 

[100    \^Uh\ 

.  4i»73 


brium,  by  putting  into  die  kft  fcale^ 

Mr,  Troughton's  weights.  No.  1 2 

No.   9 


Weight  of  the  cylinder  in  water 


grams. 

s  2048 
s=     256 

200 

30 
10 

4 
1,10 

as  2549iio 


*  When  the  cube  w»i  iauDerftd,  the^  water  in  the  glafs  }tx  ftood  i{  iDchet  higher  than  when  the  counter* 
foife  for  this  M^^er-fcale  wm  adjufted,  apd  found  to  be  441,75  grains  (fee  §.  t8.) ;  and  t  inch  of  alteration  in 
the  height  of  the  water  having  i(ppei^«d  to  be  ip*  0^0354  grain  in  weight  (§.  i9.)»  e^  inches  will  be  ■«  0,079 
grain  ;  and  fo  much  mud  be  added,  to  Qomd  for  the  lofs  of  weight  in  the  four  wires  that  fufpended  th« 
icale  and  cube  in  water..  When  the  cube  was  immerfed,  the  furfice  of  the  water  ftood  1,5  inch  below  the 
top  of  the  glafs  jar,  and  9,7  inch  below  the  centre  of  the  bean,  or  index  point. 

When  the  cube  w«t  in  the  water,  the  bean  was  clearly  feniible  with  to  of  *  g^'"* 

Add 


a  Standard  df  freight  and  Meafure, 

Add  the  corre£lion  frr  the  lofs  of  weight  of  the  four  -wires,  by  being! 

1^  inch  deeper  imnficrfcd  in  the  wattrj^  than  when  the  coumerpoife  wail>  s  + 

adjufted  -  -  -  -  '  •  -'     '      •  j 


M9 


0,05' 


Corredled  weight  of  the  cyhnder  in  water  -  -  -  -         =  2549,15 

After  this  experiment,  I  difcovercd  that  ibtne  fmall  bubbles  of  air  had  infinufted  themfclve* 

between  the  cylinder  and  the  fcale  in  which  it  hung ;  thefe  therefore  were  removed,  and  the 

experiment  repeated,  as  follows :  t  .  .      .  .        . 

*  In, order  that  this  and  fome  other  correftions  may  be  the  more  cafiiy  applied,  !I  hkr%  compilted  the  three 

following  tables,  to  be  ufcd  whenever  great  accuracy  is  required.  '  '  • 

Table  I.  Shewing  the  e>p«ifioB  of  caft  brafs,  both  in  length  and  folidityj  and  alfo  of  water,  in  fplidityf  by 
the  effect  of  heat :  the  former  k'dcri?ed  from  Mr.  Smeaton't  ezperimentt  (Phil.  T^f.  toL  XLVIITJ); 
nd  the  latter  from  fome  of  my  own,  when  I  wa»  a  refident  member  of  the  univerfiy.of.  Oxfoc4« 


Degree* 

Ea9anfi->n 

of  Braft. 

of  Heat. 

1 

In  L^o^iA.      1 

in  Scud    y 

In  Solidity.   ^ 

0       1  Milliomh  Parts.  | 

Millionth  Partst 

MilliontJi  Parts. 

I 

I. 

I    ■• 

165         / 

% 

X 

6 

330 

3 

3 

9 

495 

4   , 

4 

la 

j66o 

5 

r 

16 

8m 

6 

19 

990 

7 

7 

%%' 

"55 

8 

8 

M 

i3»o. 

9 

9 

1485 

.K>      1 

«o»4 

31 

r        1650 

Table  If.    Shewing  the  corre^pn  for  the 

.  wires,  or  the  diminution  of  the  weight  of 

the  water-fcales,  by  immerfion  in  water. 


Table  III.  Shewing  the  corcoaioii  of  tht  we%htof.tbe 
fpbere  in  air,  on  account  of  the  weighti  or  beat,  of  the 
ftraofphere. 


fion  in  Wa- 
ter. 

The  4  Wires 

of  the  Cube,  or 
Cylinder. 

.Tbc  3. Wires 
of  the  Sphere 
lofe 

Inches. 

Grains.          |         Grains.          | 

% 
3 
4 

5 

6 

■      7 
8 

9 

10 

20 

—  0,035 

—  0,071 
•—0,106 

—  0,14a 

—  0,177 

—  0,11  a 
-^0,248 

—  o,t83 

—  0,319 

—  0,3  5  A 

—  0,708 

—  0,078 

—  0,157     . 

—  0,235 

—  0,314 

—  0,39a 

—  0,471 

-  Z%^ 

—  0,706 

—  0,785 

—  1,570 

■ 

• 

Therm. 

CorrediMi- 

Inch-Vo- 

Grains. 

0 

Grains. 

»9»5 

0,00 

50 

0.00 

1 

—  ,12 

+  0,10 

X 

»*3 

o,ao 

•    * 

>35 

0,30 

4 

'*2 

040 

I 

>58 

0,50 

6 

t7* 

0,60 

.  1 

•81 
>94 

IZ 

9 

1,05 

0,90 

14 

«>I7 

fO 

»fOO 

N.B.  If  the  btiMMtcr  It  Mow  994  iacbet^  or  t^  Cfacr-| 

■mneler  below  50^,  afe  the  cootiafy  fignt.                      J 

Jf,  B.  80  inches  in  length,  of  the  wires 
for  the  fcales  for  the  cube  and  cylin- 
der weigh 

therefore  1  inch  will  be  ,077  grain,  7  .^ 
and  4  wires  of  i  inch        -       j  '*" 

J^ifb,  91  inches  of  the  wire  for  the  >  _ 
fphei^  weigh  -  y  — 

and  I  infh =0,227,  v^d  3  wires  of  ) 
I  inch  -  -  y^ 

and  the  fjfkcific  graTityof  the  wire  is  « 

Vol.  Ill— July  1799. 


I 


grs. 
6,r6 


0,308 

20,71 

o,68j 
»,7 


Wat^r  being  taken  as  heavier  than  air,  as  836 :  i  (fee 
Obfenrations  in  Sa^oy,  Phil;  Tr^nf.  for  1777)*  the  baro* 
meter  being  at  29,27,  and  thermometer  51*,  a  fphere  of 
air  equal  in  bulk  to  the  braia  fphere,  viz.  «>  1 13I  cubic 
inches,  would  weigh,  when  the  barometer  was  29,5 
inches,  and  the  thermometer  509  «>  34,57  grains; 
'  and  1  cubic  inch  of  fuch  air  -  ■■  •,304 
This  corre^QD  wili  ferfe  for  any  othci  bodj  whofe  bulk 
is  known* 

X  No. 


ISO 


Exp4r$mnts  U  afartaln 


graiBt. 
"Na  12  es  2048 


Weigbu 
as  bmre 


No.   9  ss 


The  buoyancy  oQ  ^ 

llieairbubUes>s4-^ 
being  removed^  ^ 


256 
200 

10 

4 

3 

1,07 


Adddieajrrt£Hon^  ^SSSi^? 

for  the  kfi  off  _  .  ^^^ 

weight  in  thef  =  +  ^^ 
wires,  as  before  J 


And  the  more  exaAl 
we^t  of  the  cylin- >  s  2553)22 
derin  water  becomes  3 


\ 


Air/,  when  ^  ^  ^,j^^ 


with  the  temperature  60^,5 

iachct. 

and  the  barometer    29947 

iachca. 
wai  weigbed  in  water>  itsl 
centre  was  bdow  die>  ti  ^ 
furface  of  the  water       1       ^^ 


that  is,  die  cylinder  was  die  deepeft  by        -        *        •     s  i,t 

The  repetition  of  this  experiment  (hewa  how  necefiry  it  b  to  attend  to  die  moft  trifling 

circumftances :  there  were  not  more  than  three  or  four  of  thefe  particles  of  air^  and  thofe  WK 

larger  dian  a  finall  pin*s  head.    Moreover)  it  may  be  noted,  the  diftilled  water  in  which  diefe 

eiperiments  were  made,  being  afterwards  examined  with  my  (Martin's)  hydrometer,  in  the 

heat  of  60^7,  weighed  on  diat  fcale  s  1,0005  >  'o  diat  I  fee  no  reafon  for  diflidence  in  the 

quality  of  die  water. 

(§•  24.)  J  Sfn9ffis  %f  the  fnading  Experimmif. 


« 

1 

Contents  (true  to  roivw)  t^  inches 

Weight  in  air,  true  to  0,02  grain 
Weight  in  waier,  true  to  09  to  grain 
Weight  of  an  equal  bulk  of  water,  1 

true  to  0, 12  grain,  or  rmz-v       3 
Weight  of  a  cubic  inch  of  water, 

from  thefe  experiments 

C«U. 

TlMfB 

Cyrndcf. 

ThMm. 

».». 

lackct. 

124,18917 

gninf. 
32084,82 

703*03 

3»3®»»79 
252,694 

6e^ 

74,94836 

tis6o,os 
«SS3,3s 

19006,83 
*$J.6oo» 

0 

6s 

6s 
60,5 

lacket. 
299OO 

a9»47 

*  The  weight  of  a  cable  iodi  of  conmicm  or  taiia  water  has  beta  i»duMwd  about  153  graiai,  fometimct 
«*  *$3»33  griilis»  at  othen  a53,i8.  But  authors  do  aot  feem  to  have  agreed  ia  what  they  mcaat  bj  commm 
waur»  raiH  water, /mr;^  water,  J^ng  water,  and  iSJUikd  wwttr ;  for  occafionally  they  are  all  confbnaiied,  aad 
nrade  to  paTt  for  each  other  ;  and  fufficieat  notice  feemt  not  to  have  b^iea  taken  of  the  temperature  to  which 
thefe  weights  were  affigned.  See  Mania's  Fti/§/i/dm  Britmmi€tu  Lcwis'i  PhiloTophical  Coomiercs  of  Arts« 
Chsfliben't  Diaioaary,  Itj  Dr.  Rces,  ftc.  &c         ' 

The 


a  Standard  tf  Weight  and  AUaJure.  i^x 

TKe  diverfitjr  tn  die  refult  of  chde  tviro  expenmentt  is  defcrving  of  notice^  and  muft  be 
explained.  It  may  proceed  from  two  caufes,  which  we  will  now  inquire  into.  But  firft 
it  may  be  obfervedi  that  the  accuracy  in  meafuring  the  dimenfions  of  tbde  two  bodies>  a^ 
well  as  the  precifion  in  weighing  them,  has,  I  think,  been  fucb  as  to  putout  of  all  doubt  thb 
part  of  die  experiment  From  whence  then  does  this  difference  arife  ?  Either  of  two  cauies 
may  be  fufpeded ;  v/z.  the  prefltire  of  the  water  againft  the  fides  of  tbefe  two  bodies  altering 
their  volumes,  which,  it  nuy  be  prefumed^  would  have  a  greater  efFed  on  the  ciibe,  from  its 
figure,  than  on  the  cylinder,  and  in  a  diredion  agreeable  to  diis  difference ;  that  is,  it  would 
diminifli  the  capacity  of  the  cube  more  dian  that  of  the  cylinder,  and  thus  make  the  apparent 
weight  of  a  cubic  inch  lefs  in  the  experiment  of  the  cube.  But  alfo  we  fee,  that  the  cylinder 
was  weighed  at  a  greater  depth,  by  i,l  inch,  than  the  cube,  bdow  the  furface  of  the  water. 
Now,  if  it  be  true  that  water  is  compreffible*,  it  will  become  denfer,  from  its  weighty  at 
different  depths,  and  this  circumftance  would  aft  in  the  (ame  way  with  that  juft  mentioned  ; 
vi%.  would  make  the  apparent  weight  of  a  cubic  inch  lefs  from  the  expeiiment  of  the  cube 
than  the  cylinder,  which  we  fee  is  the  i^Su 

{\.  25.)  In  order  to  diffipate  thefe  doubts,  I  cauled  a  very  accurate  hollow  brafc  fphere  to 
be  made,  of  about  fix  inches  diameter,  and  of  fueh  thicknefi  of  metal,  vis.  0,13  indi,  as  to 
be  very  litde  heavier  than  water,  and  yet  of  fUch  ftrength  as,  together  with  its  form,  to  rcfift 
any  probable  change  of  bulk  by  the  prefliire  of  water. 

This  fphere,  which  has  already  been  mentioned  (§.  10.),  was  examined  in  die  following 
manner.  The  fix-indi  moveable  bar  r  (Plate  V.  fig.  .3.]  of  the  guage,  was  compared  with 
the  divided  Icale  of  inches,  fig«  i.  The  microfcopes  being  adjufted  to  exadly  fix  inches,  or 
the  interval  between  26  inches  and  32  inches,  and  the  bar  placed  under  them,  the  exceft 
above  6  inches  was  found  to  be  as  follows,  by  th^  micrometer,  nc. 

ill  trial.  id  trial,  after  rc-adjullroeftt* 

inches*  incfact. 

6+,oa55  T  6+,<io55 


,0056 
,0054 
,0057 


"♦  ^  ,0054 

,005a  J 


therm. 

r64V 


Mean  of  die  ift  trial  =r  6    ,00550  '  6    ,00536 

Mean  of  the  ad  trial  =  6    ,00536 

**Si2^"^  =  6    ^S43^inthete«pemu,eof64«'. 

(§.  26.)  The  bar  was  then  placed  in  the  redangular  gaugt  klmn^  fig.  a.  in  die  direfiion 
f  • ;  and  die  end  of  the  micrometer  fcrew  brought  to  bear  againft  it  repeatedly,  fo  as  tftouch 
without  force,  or  confiderable  preflure :  and  the  divifions  f  cut  by  the  index,  on  the  micro-^ 
BKter  phte  of  the  gauge,  were  as  foltow: 

« 

*  See  Mr.  Caoton't  experiment  in  the  Phil.  TranC  toI.  LIT. 

t  Each  thread  of  this  fcrew  it  ■■  ^  inch,  and  each  refoludoa  of  the  icrew  b  dirid^  ia:o  soo  \  ^  that 

tfery  di\inoB  oa  the  mkrometer  plate  is  »  ^J^  inch. 

X  %  Trial 


154  Bxptriments  U  a/certain 

tcrs  (hould  exceed  th<  other  by  i&o  inch ;  in  diat  cifir,  die  enor  in  the  aSiimed  ibiid  would 
not  exceed  ,600  psut  of  die  whole:  and  diis  is  a  pofition  infinitely  too  extravagant  to  be 
admitted)  when  we  reconeA>  that  this  diameter  has  been  probably  taken  to  widiin  a  tendi 
part  of  that  error. 

{§.  29.)  The  weight  of  this  ^^here,  in  air  and  in  water,  conies  next  undo:  our  confidera* 
tion  i  the  experinisiits  for  wfaidi  were  as  foUow^  made  June  11^  1797  ;  die  barometer  being 
at  29,74  inches,  aiid  die  thermometer,  in  air,  at  67®. 

Expiriment  tbi  \ft. 

The  weight  of  the  Qihere  in  air,  the  counterpoiie,  or  waght  of  the  fiade  orl  Trofgnins. 
cradle,  «  h  cf  {Vmt  V.  fig.  3.),  in  which  the  fphere  hung,  being  allowed  >  ^287 2 2,64 
for  *>  fo  that  this  was  the  net  weight  -  *  -  -  3 

gnios. 
The  fphere  and  feale  fiiliieoded  in  water,  widi  it  centre  5,6  inches?  _      .^^  ,^ 
below  die  furfaoe,  and  die  beat  66^  •  -  *      y-     3^3*17 


Dedud  the  coonterpoife,  or  weight  of  the  fade,  in  water^  with  die*)  _ 
£une  heat  of  6frS  and  fiiine  dq^  t  >^w  die  liufm      '-        j -~^S3f32 


The  diflference  is  the  net  weight  of  die  fphere  in  water  of  the  temperature  66^,7  g 

idiicfa,  deduced  firom  its  weight  in  air.  •  -  •  .         3  "^      49»*S 

Leaves  the  weight  of  a  bulk  of  water  =  the  Sphere,  in  die  temperature  66^,7  «.«qx..« 
and  5,6  inches  below  die  furface  -  -  -  -  5  -**^?*»7» 

Expirinunt  tbt  id.    Jum  16,  1797* 
The  barometer  being  at  30)i3  inches,  and  the  thermometer  at.68^ 

graifls* 

Weig^  of  the  fphere,  together  widi  die  fcale^  in  air  «  -  29165,91 

Dedttft  die  weight  of  die  ibde^  or  cdinterpoife,  in  air         •  «>  s—      5449O3 

Remains  the  total  net  weight  of  the  fph^e  in  air  •  .  • 

And,  to  reduce  this  to  the  iame  ftate  of  the  atmofphere  as  die  preceding 
oUervation,  viz.  29,74  inches  of  die  barometer,  add  the  correAion  for 
0^39  inch  (iee  table,  \*  23.)  •  »  . 

Alio  the  corredion  for  i^  of  the  diermometer  -  •  *         s:  + 

And  die  net  weight  of  the  fphere,  in  an  atmofphere  of  29,74  inches,  and?  «a..««  ^^ 

heat  of  67^  becomes  -  -  -  -  .  3       =2*1722,42 

grtiBf. 
Weieht  of  the  fphm^  widi  its  fade,  in  water,  2,7  inches?  '     •   „ 
be&w  die  fitf&ce,  and  die  diermometer  at  66S1  5  *  4o4f  7«> 

:.•.,...-■ 

I 

^  The  weight  ef  this  finle,  with  ht  3  wire^  is  sir,  was  a*  176,10  gndni. 

t  The  fphere  Imviiig  bees  weigbtd  ia  the  fime  depth  ef  water  thtt  dM  couaterpeife  to  the  fcsle  wu 
delenaiaied  ia,  no  corredion  for  the  greater  or  left  immerfioe  of  ijhe  fale-wiiet  wit  here  neceflarj ;  which 
however  will  ibmetimei  be  the  ca£e«    Sec  f'  19*  sad  table  ILof  comftioD,  |.  aj. 

From 


a  StandMrd  $/  fTiigbt  and  Miafurt, 

grains. 

From  thence  deduA  the  weight  of  the  fcak  ia  water  =:  435*09 

The  net  weight  of  the  fcale  in  water  becomes  •  =    49>^< 

To  which,  add  the  correAion  for  the  wires  of  the  fcalel 
beinfl"  immerfed  2*53  inches  deeper  now^  than  when  its  >  =r     CHIO 
wei^t  in  water  wtt  determined  (fee  table,  §•  23.)         j 

And  the  correOed  net  weight,  in  water,  is  -  -  - 

Which,  deduAed  from  its  weight  in  air«  leaves  the  weight  of  a  bulk  of7 
water  =  die  fphere,  in  temperature  66^,1  *  *  5 

Conedion  for  o^i  of  heat  •  -  -  -  - 

And  the  true  correded  weight  of  a  bulk  of  water  equal  to  the  fphere,? 
reduced  to  die  barometer  s  S9>74t  wd  thermometer  66^,0,  becomes     5 

Ejeperhmnt  tbi  yL    June  x6,  1797. 

The  true  net  weight  of  die  (phere  in  air,  reduced  to  a  ftate  of  the  barome*? 

ter  of  19,74  indies,  and  dMurmometer  67^,  as  in  laft  experiment     -       3 

grabs. 

Weiffht  of  the  fphere,  together  with  its  fcale,  in  water.l 

6,8  inches  bdow  the  furfiice;   the  thermometer  atfs  484910 

66*,i  .  .  .  .         i 

Dedud'  die  weight  of  die  fcale  in  water  -  -  435>09 


m 


gniUf 


49»8« 


s:       a867S,6i 
+  .45 

=       aW73iP6 


grwas. 

a87ia,4z 


The  difference  is  the  net  weig^  of  the  fphere  in  water*  of)  ^ 
the  temipeiatune  66^*4  •  •  3 

To  which,  add  the  corredion  for  the  wires  of  the  fcalel 
being  immerfed  5,5  inches  deeper  now,  dian  when  its  ^  -f 
weight  in  water  was  determined  (fee  table,  ^  13*)  j 


49,11 


M 


The  correAed  net  weight,  in  water,  becomes  •  .  « 

Which,  deduAed  from  its  net  wrieht  in  air,  leaves  the  weight  of  a  bulkl 
of  water  =:  the  fphere,  and  6  in^es  bdow  the  furfiicet  with  the  heat  of  >  =: 

66^yf i 

CorreSion  for  0,^4  of  heat  (fee  table,  §.  13.)  -  *  c 

The  true  correAed  weight  of  a  bulk  of  water  :=  the  fphere,  in  die  heatl 
of  66^/>,  and  with  a  prefiure  of  the  barometer  of  19>74  inches,  and  6  >  r: 
below  the  furfitte  -  -  -  -       3 


«  49»S$ 
28671,87 

+  1,81 

18674^8 


•  fhkfi  degree  difference  of  heat  in  the  water  mtUI  aker  Jthe  weight  of  the  fphere  in  water,  or  the  weight 
of  the  hulk  of  water  equal  to  it,  a«  4,54  grains ;  fo  that,  hf  hx  the  greaieft  foarce  of  error,  ia  thefe  espc* 
f  iments,  lies  in  the  difBcuItjr  of  txUXXj  knowing*  sad  preferring,  the  tunperacurc  of  the  water. 

RefuHs 


lj;6  E^tpirimnts  U  Bfc&tain  .  • 

(§•  3^'j  Rifults  of  the  Obfervaiions  of  the  Sphere  coUeSfed^ 

Correfl  weight  of  a  bulk  of  water  »  fpherc,  the  baromcftcr  '' '  ^   '    At  i  defrrh  betet 

being  at  29,74  inches,  thermometer  66<^,o.  .     .  ....     the  furfacc  of  the 

By  the  ift  obfervation"'  -  -^        .       *       '     .  -  x.  :* .  •  *  ^9yX?'»79 

2d  obfervation  -  •  .'    •  r  •  ■    .     ^8672,06 

3d  obfervatioa ^  •  -  -  28674,6s 


ft  I    !■■ 


■  ••   • 


1 5*6 
It 

5.37 


"Mfemofall  -  -  -•  -  -  28673,51 

"-Which,  I  thlnk^'  majr  felrly  be  preTumed  to  be  wthin  i  part  in  563,000  of  the  truth. 
(§•  3'*i   Now  the  contents  of  this  fphere  Aaving  already'  f§.  28.)  been  found  ta  be 

•^Trr^^T^Q  cubi9  inches s  ^^^  —  252,587  grains,  will  be  the  weight  of  a  cubic  inch 

of  difEit^  waicTy  under  the  circumftancesiboye  mentiosedyby  Mr.  Trougfatoi^'s  weights  *. 

I  think  it  may  now  be  concluded,  diat  the  variety  in  the  experiments  of  the  cylinder  and 
die  cube,  (§.  24.}  does  not  proceed  from  die  .'diffirirent  ideptbs.'-^  in  the  water,  at  which  they 
were  ni^e ;  at  leaf!:,  that  the  preiTure  of  3.indies,  in  perpendicular  height  x)f  water,  does  noC 
rehdtr  that  fluid  qiore  denfe  by  «oioo  pafl^  urtiich  may  be  reckoned  an  infenfible  quantify;, 
but  that  this  variety  did  proceed  from  a  difference  in  the  yielding  of  the  fides  of  the  cube  and 
the  cylinder*  And  laftly,.!  hope  it  may  be  truftcd,  that  t!ie  weight  of  i  bulk  of  water  »» the 
fphere,  has  been  determined  to  within  ,«ioo  ^^  ^  whole,  and  probably  to  within  half  that 
quantity,  .  ,,  ,-  .  .  ,  ;  ••    -  f  ;  ..       .  '. 

(i*  3^0  Having  then,  through  the  means  of  Mr.  Whitehurft's  obfervadons,  and  of  his 
own  inftrument,  afcertained  the  ki^gth  of  his  proppied-flaodard,  !)i  the  latitude  of  London^ 

113  feet  above  the  level  of  the  iea}ii  under  a  denfity  oTthe  atmo^ere  correfponcfing  to  30 

•  •      •  1 

^  But,  as  will  appear  hereafter  ({.  41.%  thefe  weights  arc  too  laghtr  when  compared  with  the  ftandard  in 
the  hoofe  of  commons,  by  about  i  in  i$X3,9£;  die  corre^ion,  therefore,  for  thi»  di^rence,  would  be 
4«  0,165  grain,  to  be  deducted  from  .       •  « r  •  -  252,587  grains. 

—       ,165 


And  the  weight  of  %  cubic  inch  of  diftilled  water,  in  grains  of  the  pariiaaentary  ftandard,  > 
will  be  .  -  -  .  -  .  -         ]  -252,412 

..  t  %  >^*M  ^^"^  alteration  and  addition  to  my  apparatiu,  lince  the  experiment  above  mentioned  was  made, 
I  have  been  able  to  repeat  it  at  greater  depths  below  the  furface  of  the  water,  via.  fvhen  the  centre  of  the 
^here  was  5  inches,  S3  inches,  and  ai  inches,  below,  without  any  appearance  ^f  water  having  a  fenfible  dif- 
fierence  of  denfity  a^  diflerent  depths.  The  veflel  I  ufed  for  this  purpofc  was  of  wood,  32.  inches  high,  and 
IS  fquare,  containing  16  gallons,  with  two  fides  of  plate*glafs,  to  admit  the  lights  and  the  wires  by  which 
die  fphere  were  fufpended  were  45  inches  long,  and  fironger  than  before,  via.  100  inches  of  the  fingle  wire 
weighed  24,14  grains  |  and  due  allowance  was  made  for  the  different  weight  of  the  fpale  and  wires,  in  air  and 
w^er,  from  actual  experiment. 
%  The  height,  as  I  have  been  iaformed,  of  the  room  of  Mr.  Whitekwit's  obfervations. 

inches 


^   m  Standard  of  Weight  and  Meafun*  l^f 

inches  of  the  barometer,  and  6q^  of  the  thermoqieter,  which  is  full  as  CatisfeAory,  for  all 
pradical  purpofes,  as  if  it  had  been  done  in  vacuo  ♦,  which  I  conceive  to  be  nearly  impof- 
fible  ;  and,  having  determined  the  weight  of  any  given  bulk  of  water,  compared  with  this 
c6mmon  meafure,  'L  believe  it  now  only  remains,  to  afcertain  the  i)roportion  of  thi&  common 
sneafure  and  weight,  to  the  commonly-received  meaiures  and  weighls.of*this  kingdom. 

(§•  33O  I^  is  perfeaiy  true,  that  if  I  chofe  to  indulge  in  fanciful  fpeculation,  I  flight 
negle£l  thefe  comparifons,  as  an  unphilofophical  condefcenfion  to  modern  convenience,  or  to 
ancient  practice,  and  might  adopt  fome  more  magnificent  integer  than  the  EngUJh  p$und  of 
fathom  ;  fuch  as  the  diameter  or  circumference  of  the  world,  i^c  t^c.  and,  without  much  (kill 
in  the  learned  languages,  and  with  little  diiSculty,  I  might  ape  the  barbartfms  of  die  prefenC 
day.  But  in  truth,  with  much  inconvenience,  I  fee  no  poffible  good  in  changing  the  qgan- 
tities,  the  divifions,  or  the  names  of  things  of  fuch  conftant  recurrence  in  common  life  ;  I 
fliould,  dierefore,  humbly  fubmit  it  to  the  good  (enfe  of  the  people  of  thefe  kingdoms  at  leaft, 
to  preferve,  with  the  meafures,  the  language  of  their  fore&thers*  I  would  call  a  yard  a  yard, 
and  a  pound  a  pound,  without  any  other  alteration  than  what  the  preciiion  of  our  own  artifts 
tnay  obtain  for  us,  or  what  the  lapfe  of  ages,  or  the  teeth  of  time,  may  have  required. 

(§.  34.)  l^he  difference  of  the  length  of  the  two  pendulums,  from  Mr.  Whitehurft*» 
obfervations,  appearing  to  be  59989358  inches,  on  Mr.  Troughton's  (cale  ;  and  a  cubic  inch 
•F  diftilled  water,  in  a  known  ftate  of  the  atmofphere,  having  been  found  to  weigh  252,587  troy 
grains  according  to  the  weights  of  the  fame  arifb,  it  remains  only  to  determine  the  proportions 
of  thefe  weights  and  meafures,  to  thofe  that  have  been  ufually,  or  may  be  fitly,  confidered  as 
the  ftandards  of  this  kingdom ;  and  herein  a  fmall  difcrepancy  between  themfelves,  in  theie 
authoritative  ftandards,  witt  have  no  influence  on  the  general  condufion  I  propofe  to  draw; 
which  is,  not  fo  much  to  (ay  what  has  been  the  fbndard  of  Great  Britain,  as  what  it  Jhall  be 
henceforward,  and  may  be  immutably yi  ;  and  which  (hall  differ  but  a  very  fmall  quantity, 
and  that  an  aflignable  one,  from  thofe  diat  have  been  in  ufe  for  two  or  three  hundred  years 
paft.  By  thefe  means,  no  inconvenience  would  be  produced  from  change  of  terms,  or  fubdi- 
viflons  of  parts,  or  from  fenfible  deviation  from  ancient  practice :  all  that  wiU  be  done,  wiQ 
be  to  render  that  certain  and  permanent,  which  has  hitherto 'been  fluduating,  or  liable  to 
fluduadon.  To  give  effeA  and  energy  to  thefe  fuggeftions,  is  the  province  of  another 
power. 

*  It  is  ptrk€dy  trae,  that  this  fuppofes  the  experiment  to  be  made  with  a  pendulum  fimilar  to  Mr.  AViijte» 
liurft's. 

{To  he  concluded  in  a  future  Number.) 


Vol*  III.— July  I799»  Y 


15I  Jmfr^vement  9/  Ink  for  writing, 


ni. 


On  cin0im  ufffkt  Pr9pirisi^  ef  ibt  Oxyginattd  AAirUtic  AdJL    By  $k$  Rev.  AiEXANDEi 

JoBN  FoRsrra*. 


T, 


HE  oxygenated  nmriadc  acid  has  of  late  been  employed  with  mu^k  fuccefi  (a  the  art  of 
Ueaching  and  difiAarging  colour ;  but  I  do  not  know  that  any  one  ha^  hitherto  obferved  that 
its  combinations  widi  alkalies  and  earths,  not  only  poflefTes  the  property  of  difcharging  colour, 
but  alfo  of  brightening  and  rendering  many  colours  much  more  intenfe. 

As  I  hope  that  infimnation  on  this  fubjeA  may  be  acceptable  to  foqie  of  your  readers,  I 
^fliaU  give  you  an  account  of  a  few  experiments  made  with  the  oxymuriate  of  carbonated  pot- 
afli  with  an  intention  not  to  difcfaai^»  but  to  brighten  colours.  I  preferred  this  (alt,  having 
a  coniiderable  quantity  of  it  ready  made,  and  from  a  few  experin^pits  tried  with  the 
oacymuriates  of  carbonate  of  ibda,  foda,  and  lime,  I  thought  they  were  more  apt  to  difcharj^e 
Ae  colour,  and  feldom  produced  it  fo  c)ear  as  the  former.  Until  very  lately>  I  did  not  think 
of  making  any  experiments  with  the  oxymuriate  of  ammponiac,  but  from  thefe  I  am  led  to 
fuppofe  that  it  will  have  a  ftill  better  efied  than  the  oxymuriate  of  carboiuited  potaA^. 

I  diicovered  this  property  of  the  oxymuriate  of  carbonated  pota(h  by  accident ;  having 
dropped  a  little  of  the  aqueous  folution  of  diis  ialt  upon  dean  writings-paper,  when  the  paper 
became  dry,  I  was  furprifed  to  Ice  my  ink  write  much  blacker  where  the  (aline  (plution  had 
i^read,  than  any  where  elfe.  I  then  fpread  ibme  of  die  oxygenated  muriatic  acid  upon  dia 
fame  paper,  but  here  the  ink  became  lighter  coloured  than  ufual.  J  mixed  a  little  ink  in  a 
phial  with  clear  water,  and  dropped  into  it  a  fmall  quantity  of  the  above  falinc  folution;  at 
firft,  the  ink  became  remarkably  black,  but  whenever  it  had  attained  its  greateft  intenfity,  the 
very  next  drop,  in  fume  degree,  discharged  the  colour.  After  many  trials,  being  perfuaded 
that  diis  (aline  iblution  when  properly  u(isd  would  improve  ink,  I  filled  a  quart  bottle  witb  the 
thinneft  part  of  common  ink  poured  off  from  the  fediment,  and^  made  it  as  black  as  poffible 
widi  this  fiiline  iblution.  It  has  now  ftood  without  being  moved  jfor  two  mpnths,  has  let  &U 
no  precipttatf,  writes  remarkably  black  (which  to  many  people  would  be  a  very  great 
recommendation),  flows  eafily  from  the  pen,  and  continues  upon,  the  paper  much  blacker  dian 
any  patent  ink  I  have  ever  feen  of  the  (ame  thicknefs :  ink  with  litde  gum  in  it  anfwers 
jbeft,  becaufe  the  (aUne  fohitton  precipitates  from  gum  a  white  fubftance,  infoluble  in  water. 
If  is  likewife  proper,  not  to  add  fo  much  of  the  faline  folution  as  to  make  the  ink  periedly 
black  all  at  once,  for  it  improves  by  (landing  in  the  bottle,  and  there  is  lefs  danger  of  any  of 
the  colour  being  difcharged.  Of  the  (aline  foludon  which  I  u(U,  two  drachms  and  forty 
grains  was  fuflicient  for  a  quart  botde  of  ink,  or  one-fifth  part  of  the  weight  of  the  fulphates 
^f  iron  and  copper  ufed  in  the  compofidon  of  the  ink  to  he  improved :  this  proportion  occafiona 
no  precipitation  of  the  metallic  oxids. 

•  ComixniJiicated  by  the  Author. 

Having 


Advantag9s  of  O^muriate  of  Potajh  in  Dying.  159 

Having  remarked  the  good  effeft  which  the  oxygenated  muriate  of  carbonated  potafh 
produced  upon  ink,  I  next  tried  if  it  wouM  improve  the  colour  of  the  fubftances  commonJIy 
nifed  in  dying.  The  aqueous  extrad  of  galls  by  a  fmall  addition  of  this  faline  folution  at  firft 
becomes  a  little  white  and  turbid,  a  litde  more  immediately  renders  it  as  dark  coloured  as  it 
becomes  by  long  expoTure  to  the  adiion  of  the  aif  and  light;  ftill  more  of  the  faline  iblation 
difcharges  the  dark  colour,  and  changes  it  to  a  kind  of  yellow :  but  galls  require  a  much 
greater  quantity  of  the  fait  to  difcharge  their  colour,  than  any  vegetable  colouring  fubftance 
I  have  tried.  The  colours  of  logwood  and  weld,  are  rendered  much  brighter  and  more 
intenfe  by  the  faline  folution :  cochineal  and  archil,  are  improved :  the  colours  of  brasil 
wood  and  madder,  are  little  altered*  But  if  a  folution  of  alum  be  poured  into  the  aqueous 
extraA  from  any  of  the  abovementioned  fubftances,  and  fuffered  to  remain  at  reft  until  no 
more  precipitate  falls  down,  and  if  the  clear  liquor  be  then  poured  off*,  and  a  little  of  the  (aline 
folution  mixed  with  it,  |i  very  abundant  and  better  coloured  precipitate  immediately  fubfides*  * 
By  adding,  alternately,  folotions  of  alum  and  oxygenated  muriate  of  carbonated  potalh^ 
the  whole  of  the  colouring  particles  may  be  precipitated  from  the  liquor,  and  thus  a  much 
more  abundant  and  better  coloured  precipitate  procured,  than  could  have  been  got  by  ufing 
alum  alone.  Great  orre  muft  be  taken  not  to  add  too  much  of  the  faline  folution  at  one  time« 
for  if  any  of  the  colour  is  difcharged,  it  cannot  be  recovered.  It  is  likewife  proper,  to  add 
little  of  the  alum  at  one  time,  for  too  much  of  it  injures  the  colour,  and  the  firft  precipitates 
are  generally  the  beft.  No  heat  muft  be  applied  after  the  addition  of  the  (aline  folution :  the 
colour  of  all  the  preparations  I  could  make  of  indigo,  was  injured  or  difcharged  by  being 
treated  with  diis  (aUne  folution. 

As  yet,  I  have  tried  the  effeft  die  folution  of  this  (alt  would  have  upon  the  dying  of 
cotton  with  weld  only,  and  in  every  inftance  it  has  been  an  improvement  where  the  fmall 
pieces  of  cotton  were  of  the  (ame  quality,  immeried  in  the  (ame  mordants  and  colouring  baths, 
for  the  fame  length  of  time,  with  this  difference  only,  that  before  one  of  them  was  taken  out, 
a  little  of  the  faline  folution  was  added  to  the  colouring  bath,  the  colour  was  brightened  by  the 
addition,  and  about  one-third  part  lefs  wdd,  produced  the  (ame  (hade  as  when  none  of  the 
(aline  folution  was  ufed.  The  bath  muft  be  cold  before  the  fidine  folution  is  added,  otherwife 
the  colour  will  be  injured ;  and  I  imagine  that  this  fait  will  be  employed  to  moft  advantage, 
where  the  ftuiF  to  be  dyed  is  immerfed  in  a  cdd  colouring  badi«  It  certainly  has  a  tendency 
to  extrad  the  colouring  particles  from  the  dye,  and  to  brighten  them  when  cold,  but  in  every 
cafe  injures,  and,  in  fome  cafes,  entirely  difcharges  their  colour  when  virarm. 

I  cannot  precifely  (ay,  to  what  degree  the  carbonated  potafh  ought  to  be  (aturated  with  the 
oxygenated  muriatic  acid,  fo  as  to  produce  the  beft  poifible  tSeSt  upon  colours ;  but  I  have 
found,  that  the  degree  of  faturation  has  a  powerful  influence,  and,  in  many  cafes,  changes  the 
(bade  of  colour  completely*  Different  Colours  alfo  require  different  degrees  of  faturation  in 
the  fait,  fo  that  a  great  many  experiments  muft  be  tried  before  it  can  be  exa^y  afcertained 
what  will  anfwer  beft  in  every  cafe:  for  ink,  it  (hould  be  fiiturated  to  fuch  a  degree,  as  that 

Y  2  ''  bubbles 


x6o  '  Upf^*^  JppHcathns  of  Oxymurtafe  rf  Petajh, 

0 

bubbles  of  air  are  juft  beginning  to  rife  in  the  falinc  liquor  in  the  operation  of  making  it:  or 
if  it  is  faturated  above  that  point,  a  litde  more  alliali  may  be  added,  or  the  phial  in  which  it 
is  prefefved,  may  be  left  open  until  the  air-bubbles  ccafe  to  rife. 

I  have  obfcrved  in  all  the  experiments  made  with  this  (ait,  that  it  produces  the  fame  effecSr 
upon  moft  colours  as  expofure  to  the  air  and  fun,  with  this  difference  only,  that  its  operation 
IS  much  more 'rapid  and  complete:  therefore,  I  have  accounted  for  its  effefts,  by  fuppofmg 
that  when  a  proper  quantity  of  the  fait  was  added,  the  colouring  particles  attracted  as  much  of 
oxygen  from  the  fait,  as  was  fufficient  to  give  them  their  greateft  degree  of  intenfity  and 
brightncfs ;  but  when  too  much  of  the  fait  was  added,  fo  much  oxygen  united  with  the 
colouring  particles  as  to  oxydatc  them  comjjletely,  and  deftroy  their  colour :  probacy  the 
.  indigo  (the  colour  of  which  is  more  or  lefs  difcharged  by  all  proportions  of  this  faline  folution) 
is  fufficiently  oxygenated  in  the  operation  of  making  it. 

As  in  all  the  experiments  tried  upon  colours,  the  oxygenated  muriate  of  carbonated  potafh 
produced  a  better  effeft  than  the  oxygenated  muriate  of  potafh ;  it  is  probable  that  the 
carbon,  or  carbonic  acid,  aSs  a  very  important  part.  What  renders  this  more  probable  is,  that 
charcoal,  when  ufed  for  purifying  any  fubftance,  but  particularly  ardent  fpirits,  extrad  of  galls, 
or  water  become  putrid,  by  (landing  too  long  in  glaiTes,  with  fldwers,  &c.  if  left  on  the  filter, 
expofed  to  the  air  and  fun,  and  not  fuffered  to  dry  too  quickly,  aflumes  a  variety  of  beautiful 
colours,  principally  blue,  yellow,  and  purple.  When  the  colour,  therefore,  is  improved  by  die 
oxymuriate  of  carbonated  pot-afh,  both  the  oxygen  and  carbon  may  unite  with  the  colouring 
particles,  and  produce  a  joint  cffeft.     < 

The  oxymuriate  of  carbonated  potafti,  when  not  ufed  in  excefs,  precipitates  many  of  the 
metals  from  their  fol  vents,  with  a  great  deal  of  colour,  and,  in  many  cafes,  may  be  advan- 
tageoufly  ufed  to  deteA  the  prefence  of  a  metallic  oxyde  difTdved  ii\  water. 

Soap  is  improved  by  mixing  it  with  a  fmall  proportion  of  this  faline  folution ;  common  ibap, 
if  well  mixed  with  it  in  a  mortar  till  it  becomes  white,  anfwers  better  for  wafliing  the  hands, 
or  (having,  than  any  of  the  kinds  of  foap  moft  ftrongly  recommended  for  thefe  purpoies. 

All  the  fat  and  expre(red  oils  are  rendered  as  white  as  milk,  and  partly  ibluble  in  water,  by 
mixing  them  with  this  faline  folution;  and  they  may  be  reftored  to  their  former  fhte,  by  a 
fmall  addition  of  any  of  the  mineral  acids,  excepting  a  fmall  quantity  of  a  mucilaginous  fub« 
ftance,  which  remains  for  a  while  fufpended  in  the  water,  and  at  laft  coUefb  upon  its  fur&ce  : 
common  whale-oil  .treated  in  this  way,  lofes  much  of  its  offenfive  fincU,  and  becomes  better. 

Thefe  arc  a  few  of  the  obfervations  I  have  lately  made  upon  the  effe^  produced  by  oxyge* 
nated  muriate  of  carbonated  potafh.  Though  I  have  not  had  an  opportunity  of  making  fo  many 
experiments,  or  of  confidering  their  refults  with  all  that  attention  which  diey  feem  to  defervc^ 
yet  as  many  of  them  are  entirely  new  to  me,  and  promifc  to  be  ufeful  to  fociety,  I  have  pre- 
fiimed  to  lay  them  before  the  public,  even  in  their  preient  imperfcd  ftate>  through  the  mediuni 
#f  your  very  excellent  publication. 

Belhihf^i^  Abndcen^  Jum  2,  i799,  A.  I.  F. 

On 


«     • 


GeHtrathn  ef  Htat  in  th*  CmihuflloH  of  Fuel, 


i6 


T, 


IV. 

On  the  Management  of  Fire^  particular^  with  Regard  to  the  ConftruSilon  of  Boilers. 

By  Benjamin^  Count  of  Rum  ford*. 


HE  fixth  of  Count  Rumford's  experimental  cflkys  is  divided  into  fix  chapters.     In  the 
firft,  the  curious  and  interefting  nature  of  the  fubje£t  is  difplayed,  and  the  importance  of 
ceconomy  in  fuel,  is  ftrongly  impreiTed.   It  is  ftated,  in  general  terms,   that  no  lefs  than  feven- 
cighths  of  the  heat  which  might  be  produced  and  ufefully  applied  from  any  given  quantity  of 
fuel  is  loft  in  the  common  methods  of  application.     But  not  to  leave  the  fub]e£l  to  reft  upon 
general  induction,  the  author  proceeds  to  relate  various  interefting  experiments  which  fhew  the 
difference  of  eiFefl  with  the  fame  vefTcK   Accordingly  as  the  fire  was  applied  in  the  common^ 
method  without  confining  it>  or  according  to  the  improved  methods  of  the  Count,  theproportions- 
of  fuel  required  to  raife  the  temperature  of  equal  quantities  of  water^  difitred  incomparably 
more  than  common  obfervers  might  have  been  led  to  expeiSl.     In  this  fijjft  chapter,   the    . 
Counik enters  into  the  midft  of  his  fubje(Sl>  by  giving  a  defcription  of  the  arrangements  in  the 
kitchen  of  the  houfe  of  induftry  at  Munich;  the  conftfu£lion  and  judicious  provifions  of  the 
fire-place,  the  form  of  the  vefiels  and  their  covers,  and  the  laving  of  heat,  by  caufing  the  fteam^ 
and  even  the  fmoke,  to  perform  ufeful  offices.  He  ftates  the  advantages  of  wooden  boilers  in  many 
cafes,  over  thoie  of  metal,  and  after  an  interefting  detail  of  particulars,  we  arrive  at  the  valuable 
hSt^  that  the  quantity  of  fuel  confumed  in  this  eftablifbment  is  only  one-tenth  part  of  what 
is  required  to  produce  like  proportional  efFe£):s  in  private  families.     This  narration,  is  followed. 
by  accounts  of  ibme  of  the  provifions  in  the  conftruAion  of  the  beft  fire-places,  and  the  figure  '^ 
of  the  boilers,  and  is  concluded  by  a  confeiEon,  which  doe^  honour  to  the  underftanding  and. 
the  principles  of  the  Author :  namely,  that  the  want  of  methoil  in  this  chapter^  is  intentional  ^ 
that  he  was  defirous  rather  of  writing  a  ufefiil  book,  thaa  a  (plendid  performance  ;  for  which^ 
purpofe  be  rather fhofe  to  decoy  the  reader  into  a  fituation  where  he  fhould  have  an  inviting. 
view  of  the  whole  profpe£l,  than  to  preicnt  a  regular  (eries  of  elementary  principles    to  the 
multitude,  who  have  neither  time  nor  patience  to  labour  through  fo  abftrufe  a  fubje£t. 

The  ibcond  chapter  accordingly  preients  us  with  a  popular  and  perfpicuous  account  of  the 
generation  of  heat  in  the  combuftion  of  fueL    Whether  heat  be  matter  or  motion,  forms. no* 
part  of  the  prefent  difcuffion  ;  the  laws  of  its  action  conftitute  the  obje£t  of  pra£Ucal  rcf^arch. 
Whether  the  heat  be  afforded  exclufively  by  die  air,  which  is  decompofed  in  combuftion,  of 
not,  it  is  evident  that  the  quantity  wiU  be  greater  or  left,  accordingly  as  the  combuftion  or 

*  In  coafcqucnce  of  the  letter  received  from  my  correfpondent  W*  ^^  p.  86  of  the  prefent  volume,  I  ap- 
plied to  Count  Rumforili  for  permiflion  to  copy  the  engravings  which  conftitute  plateVlil.  of  the  prefent  number^ . 
which  he  granted  with  the  utmoft  readinefs.    As  the  whole  of  the  prefent  article  confifts  of  abridged  matter 
from  hit  iixth  eflay,  or  fuch  remarks  and  fa£ts  as  I  have  received  from  him  in  converfation,  I  have  t-tuughc  ir 
moft  proper  to  fubjoin  his  name  to  the  title,  though  I  have,  for  the  fake  of  concifenefs,  ufed  my  own  language, 

and  have  fpokcn  of  him-  Ia  the  third  perfoiu 

decompcAtioo. 


i62  Theory  tff  Combuftion^  applied  to  the  Improvement  of  Fire-places. 

decompofition  of  the  fuel  is  more  complete.  This  greatly  depends  on  the  ftream  of  airi  which 
pafles  through  the  burning  fuel ;  that  is  to  fay,  upon  the  velocity  of  this  ftream,  which  muft 
be  definite,  in  order  to  produce  the  greateft  poffiblc  efFeft  with  fuel  of  any  particular  kind. 
Without  air  there  is  no  combuftion  ;  a  fmall  portion  of  air  will  maintain  the  combuftion  but 
feebly;  a  greater  quantity  will  give  intenfity  to  the  heat,  and  rapidly  decompofe  the  air  and  the 
fuel ;  a  flill  greater  quantity  will  carry  off  more  heat  than  it  can  generate,  that  is  to  fay,  it 
will  blow  the  fire  out  *.  The  current  of  air,  by  which  a  fire  is  excited,  may  be  made  to  flow 
by  mechanical  me^s,  fuch  as  bellows ;  or  by  the  ilatical  tWtSt  of  its  own  expanfion.  This 
laft  is  the  common  procefi  operated  by  diinmies ;  and  it  is  of  great  practical  advantage  to  be  able 
to  regulate  thisairrent.  If  we  fuppofe  the  dimenfions  of  the  fire-place,  ^  and  the  height  of  the 
chimney,  to  be  fuch  as  are  beft  calculated  to  produce  a  rapid  combuftion  of  the  fuel,  it  may,  in 
many  inftances,  be  defirable  to  moderate  that  combuftion,  by  diminifhing  die  quantity  of  air  ; 
diis  is  done  by  perfe£Uy  clofing  the  door  or  aperture,  through  which  fuel  is  conveyed  to  the 
fire-place,  and  by  fecuring  a  command  of  the  other  two  paflages,  namely,  that  of  the  afli-hole 
under  the  grate  and  that  of  the  chimney,  by  proper  regifters,  which  may  be  opened  to  any 
required  extent,  'or  clofed  at  pleafurc*  By  thefe  arrangements,  tb^  combuftion  is  governed  by 
the  operator,  and  may  be  entirely  ftopped  by  clofing  both  regifters.  The  Author  obferves, 
that  nearly  the  fame  efl^e£ls  as  thofe  of  the  chimney  regifter  may  be  produced,  by  caufing  the 
fmoke  to  defcend  feveral  feet  after  it  has  quitted  the  fire-place  before  it  afcends  again ;  andfi-om 
a  late  converlation  with  him^  I  underftand  that  this  defcent  is  of  the  utmoft  importance  and  value  in 
its  effect.  As  the  cooled  air  or  vapour  always  occupies  the  loweft  place,  it  muft  follow,  that  no 
part  of  the  ftream  can  pafs  up  the  chimney,  till  it  has  imparted  fo  much  of  its  heat,  as  to  caufe 
it  to  defcend  to  the  bottom ;  whereas,  in  the  ordinary  form  of  chimnies,  it  is  the  moft  heated 
part  which  flies  immediately  and  rapidly  up  the  chimney.  Many  fire-places  have  been  greatly 
improved  by  this  fimple  addition.  The  fize  of  the  fire-place,  as  well  as  of  the  fuel,  are  both  of 
confiderable  importance.  The  air,  which  in  common  conftru£lions  is  fuffered  to  pafs  over 
the  fire,  is  a  thief  which  carries  off  heat  without  aififting  the  combuftion :  a  large  grate, 
partly  covered  with  fuel,  produces  a  fimilar  effe£t  by  admitting  air  through  the  vicinities, 
which  fimply  becomes  heated  by  robbing  the  boiler,  and  the  reft  of  the  apparatus  with  which 
it  may  come  in  contact.  The  Count  recommends  a  grate  in  the  form  of  a  fegment  of  a  fphere, 
which  affords  the  advantage  of  the  fuel  rolling  to  the  loweft  part,  as  it  becomes  fmaller;.  and 
he  gives  the  form  of  a  cone  to  the  paffage  beneath  the  grate,  converging  downwards,  till  the 
diameter  becomes  only  one  third  of  that  of  the  grate.  Inftead  of  the  grate  itfelf,  he  has  intro- 
duced earthen  pans  perforated  widi  holes  to  admit  the  air,  and  thinks  they  anfwer  even  better 
than  the  grates  themfelves. 

The  heat  generated  in  the  combuftion  of  fuel,  manifefts  itfelf  in  two  virays  \  namely,  in  the 
bot  vapour  which  rifes  from  the  fire,  and  in  the  rays  which  pafs  off  in  ftraight  lines  in  all  di- 
reiStions.    It  is  not  known  what  proportion  this  radiant  heat,  as  it  has  been  called,  bears  to  that 

*  Philofophical  Journal,  I.  515 

which 


Pr9duilion  and  Confifument  of  Heatj  Clothings  fie.  163 

iwliicb  pailcs  ofF  in  flame  and  heated  vapour.  It  feems  probable  that  it  may  vary  according  to 
the  volatility  of  the  combuftible  matter  and  other  circumftances ;  but,  in  general,  it  feems 
that  the  quantity  of  the  former  is  much  lefs  than  that  of  the  latter.  Open  fires  warm  apart^- 
ments  by  their  radiant  heat  only,  all  the  heat  of  the  vapour  being  entirely  loft.up  the  chimney. 
It  is  a  remarkable  fiiA,  that  radiant  heat  is  emitted  in  great  abundance  by  all  bodies  which  are 
capable  of  ignition,  whether  they  be  folid  or  fluid,  combuftible  or  incombuftible. 

The  means  of  confining  beat  and  directing  its  operations,  conftitute  the  objed  of  the  third 
chapter.  It  is  well  known  that  heat  paflies  more  fpeedily  through  fome  bodies  than  others.  The 
ufeful  applications  of  this  property  are  feen  in  a  variety  of  inflances  ;  among  which,  the  wooden 
handle  of  a  tea-pot,  and  the  cloth  made  ufe  of  in  handling  hot  iron,  are  bmiliar^Asunples. 
The  Author  mentions  fome  others,  and  remarks  that  >the  conducting  powers  w  no  two 
bodies,  with  regard  to  heat,  are  exadUy  alike. 

To  confine  heat,  is  nothing  more  than  to  prevent  its  efcape  out  of  the  heated  body,  by 
furrounding  that  body  with  a  covering,  through  which  it  cannot  readily  pafs.  If  a  covering 
could  be  found  perfe£lly  impervious  to  heat,  there  feems  no  reafon  why  the  heated  body,  thus 
defended,  ihould  not  continue  hot  forever;  but  it  is  not  probable  that  any  fuch  body  exifts. 

All  metals  are  remarkably  good  condudors.  Wood,  and,  in  general,  all  light  fpongy  bodies, 
or  fuch  as  contain  fluids  in  their  interfaces,  are  bad  condudors  ^.  Mercury,  water,  and  all 
fluids,  are  condu&ors  by  circulation,  but  not  perceptibly  foin  any  other  way.  Air  and  the 
clafiic  fluids  are  very  flow  conductors,  even  when  permitted  to  circulate;  probably  on  account 
of  their  ytty  fmall  mafs:  pulverifed  bodies  condud  worfe  than  the  fame  bodies  in  the  aggregate. 
Very  dry  powder  of  charcoal  is  one  of  the  befl  we  know ;  but  common  air  is  the  f  ubflancc 
employed  by  nature  to  confine  heat,  and  is  certainly  the  beft  which  can  be  ufed. 

The  warmth  of  the  fur  of  beafls,  is  undoubtedly  owing  to  the  air  entangled  or  confined  in 
their  interflices  f.  Double  windows  and  walls,  fo  ufeful  in  cold  countries  to  confine  heat,  and 
In  hot  climates  to  prevent  its  admiffion,  operate  in  the  fame  way  %•  The  Author  proceeds  to 
give  a  fhort  account  of  his  experiments  formerly  made  on  thefe  fubjedb,  and  (hews  by  a 
curious  experiment,  that  fleam  is  not  a  conductor  of  heat  in  any  refpeft,  except  by  the 
intefline  motion  of  it  parts.  The  fame  experiment  is  applied  to  fliew  diat  heated  air  and 
vapour,  are  alfo  non-condu£tors,  and  may  be  ufed  with  the  greateft  advantage  in  our  operations 
for  confining  heat. 

Thefe  interefling  fpeculations  lead  in  the  fourth  chapter  to  an  enquiry  how  the  heat  is  com.- 
municated  from  flame  to  other  bodies.  If  the  conducting  quality  of  bodies  be  not  altered  by  any 
increafe  of  temperature  which  does  not  change  their  chemical  combination,  it  will  be  proper  to 
confider  flame  as  a  hot  wind.  It  is  necefTary,  in  order  that  a  fluid  fhould  receive  or  impart 
heat,  that  all  its  parts  fhould  fevcrally  come  into  contact:  with  the  body  which  gives  or  receives. 

Hence  a  hot  body  immerfed  in  air  is  not  cooled  except  fo  far  as  the  air  has  motion;  and  the 

•  ( 

•  Philofophical  Journal.  I.  289-295 
f  Philofophical  TranfadtiuDS,  1792. 

\  Double  walls  and  windows  are  fcarccly  ufed  in  hot  countries.  I  have  feen  light  double  ftru^ures  of  bamboo 
in  India.  N. 

cSefb 


J  64  Comnunicafion  of  Utat  from  Fire.    Fa^s  and  Expmmertts^ 

effects  of  wind,  or  a  Waft,  becomes  afUve  in  carrying  ofF  the  heat.  If  flame  be  merdy  a  hoit  * 
wind,  it  will  follow  that  the  ftream  of  a  blow-pipe,  when  ufcd  to  impel  the  flame  and  ndt  to 
excite  the  fuel,  muft  probably  2£t  by  impelling  the  ignited  vapour  with  greater  ^xe  ami  quaa- 
ticy  agaiiift  bodjes,  and  no  otherwife ;  and,  confequently,  that  carbonic  acid  gas,  or  any  other 
^laftic  fluid,  will  have  the  fame  efTevSl  under  thefe  circumftances  as  oxygen.  The  Count  found 
this  to  be  the  cafe  with  thofe  very  fluids,  as  well  as  with  atmofpheric  attt  vrging  the  flame  by 
the  blow-pipe,  and  ufed  to  fufc  the  end  of  a  ftick  6f  glais*  It  is  probable  that  this  reiult  may 
•require  to  be  modified,  and  the  experiments  varied,  in  order  to  reconcile  it  with  the  efl^eds  pro- 
duced by  the  ufe  of  oxygen,  in  fufmg  filex  and  other  incombuftiUe  bodies  by  Lavoifler,  Erhman, 
And  c|tejjs ;  but  there  is  no  doubt  that  it  is  ftrikingiy  conclufive  with  i^egard  to  the  pradi* 
cal  o^illi  to  which  our  author  applies  his  reafoning.  The  boiler  to  be  beaudmufl  mt  only  expoji 
as  large  afurface  as  pojjible  t9  AeflanUy  and  hot  .vapour\  but  kmujihe  offucb  a  form  as  tocaufe 
Jhe  flame  which  embraces  it  to  impinge  againfi  it  with  force^  to  break  againfl  it^  and  to  play  over 
itsfurface  in  edSes  and  whirlpools.  It  is  therefore  againft  the  bottom,  and  not  the  fides,  that  the 
principal  efforts  muft  be^lireded. 

The  next  chapter,  V.  prefents  an  account  of  experiments  with  fireplaces  and  boilers  of  va- 
rious forms  and  dimenfions :  a  philofophical  and  practical  courfe  of  unparalleled  fidicity,  whe- 
ther we  confider  the  ability  and  condud  of  the  diredor,  or  Ae  means  afforded  to  perform 
fthem.  la  order  to  obtain  a  refult  capable  of  comparifon,  it  is  taken  for  granted  that  equal 
'quan&cs  of  fuel  fimilarly  expended,  will  raife  the  temperature  of  water  through  the  fiune  number 
of  degrees.  Whence,  by  knowing  the  original  temperature  and  quantity  of  water,  together 
•with  that  of  the  fuel  expended  to  raife  it  to  the  boiling  temperature,  the  refult  may  be  acpreflSMJ 
by  ftating  the  -quantity  rf  water  at  32**,  which  would  have  been  raifed  i«o^  degrees  by  ilbb  of 
the  fuel  in  that  furnace  *•  The  Count  calls  this  the  precife  refukj  and  fometimes  adds  the 
4]uantity  of  water  which  might  have  been  Jcept  boiling  one  hour  by  i  lb.  of  die  fuel ;  which  laft, 
lis  he  remarks,  caiux)t  berbery  exaft. 

From  the  indifpenfable  motive  of  brevity,  it  becomes  neceflfary  to  refer  the  reader  to  die  f&j 
itfelf  for  the  particulars  of  the  refpeSive  conftrudions,  and  the  ufcful  confequences  to  which 
they  point.  I  fhall,  therefore,  mention  fome  of  the  leading  finds,  and  then  give  die  defcripdon 
of  the  furnace  and  boiler  delineated  in  the  plate. 

l^he  fuel  made  ufe  of  was  wood ;  and  it  is  a  f3&  of  no  inconfideraUe  value,  diat  pine  wood, 
which,  weight  for  weight,  cofts,  in  moft  placft,.only  half  the  price  of  beech,  affords  more  heat  in 
its  combuftion.  It  was  not  found,  as  might  be  expeded,  that  the  laving  of  fuel  was  greater  the 
larger  the  fcale  of  operation ;  but,  on  the  contrary,  the  experiments  (hewed  that  there  is  a 
maximum  of  effedl  widi  fingle  fire-places,  which  will  be  departed  from  when  the  quantities  of 
liquid  tidier  exceed  or  fall  (bort  ^a  certain  definite  ^luantity.    The  caufes  of  diis  are  pointed 

•  In  the  form  of  a  rule.  Miiltiply  the  quantity  of  water  by  the  number  «xprefling  the  degrees  a£hially  raifed; 
multiply  the  number  of  pounds  of  fuel  expended  by  180.  Divide  the  firft  produ^l  by  the  latter,  and  die  quo- 
tient will  expreCs  the  waicr  which  would  hav«  been  rai(cd  180^  by  1  lb.  of  the  fuel.  N. 

'  •Ut, 


ConJIruefion  df  tumaas.    Saving  of  FueL  165 

out,  namely,  that  flame  will  ad  more  effeflually  the  greater  the  furface ;  and  this  is  proporw 
tionally  greateft  in  fmall  furnaces :  and,  fecondly,  that  the  cooling  efFedl  of  the  mafonry  aii4 
apparatus  will  be  greater  the  greater  its  mafs ;  and  this  alfo  is  proportionally  greater  in  (xnall 
furnaces.  The  exa£l  flze  to  produce  the  greateft  efFeft  is  not  eafy  to  be  afcertained;  but  fup* 
poling  this  to  be  done,  it  will  follow,  as  the  Count  has  remarked  to  me,  that  in  all  eftabliih- 
ments  of  confiderable  magnitude,  it  will  be  better  on  this  and  many  other  accounts,  to  heat  die 
veflel  by  a  number  of  fmaller  £res,  inftead  of  one  large  one.     . 

In  the  conftruflion  hereafter  to  be  defcribed,  the  flame  was  at  iirft  made  to  circulate  round 
tiie  fides  of  the  boiler ;  but  by  iiibfequent  experiments,  in  which  the  circulation  through  thbfc  ^ 
fide  flues  was  prevented  (the  hot  vapour  being  ftill  fufFered  to  enter  them)»  it  was  found  that 
the  efied  v^as  accelerated  by  the  fpeedier  draft  of  the  chimney^  without  z^y  greater  ex- 
pence  of  fuel.  ,  ^ 

In  every  furnace  there  feetns  to  be  a  rate  of  working,  at  which  the  heat  is  more  cheaply  pro* 
tjuced  dian  at  any  other ;  that  is  to  lay;  if  there  be  too  little  fuel  in  the  fire-place  at  once,  ^he 
prooefs  will  be  longer,  and  die  lofs,  by  the  condu<^ing  power  of  the  apparatus,  more  confiderable : 
if  there  be  too  much,  the  bufinefs  will  be  performed  more  Ipeedily,  but  at  a  greater  expence^ 
thiefly  from  the  efcape  of  heated  vapour  by  the  chimney.  In  fome  cafes,  it  may  be  moft  pro- 
fitable to  (ave  time ;  in  others,  fuel.  In  the  experiments,  no.  3  c  an4  32,  it  was  found,  that 
to  abridge  the  time  oneniiird,  there  was  an  additional  confumption  of  about  on&»eighth  voffff 
fuel. 

The  progrtftve  improvements  in  die  laving  of  fuel,  as  fumraed  up  at  page  U 1  of  the  cflaj^ 
are  very  curious.  With  a  common  open  fire,  carefully  managed,  the  precife  refult  was  i.i  i. 
t>r  lib.  (rf'fuel  raifedjl^lb.  of  water  i8o^«  But  in  the  experiment,  no.  ao.  with  the  improved 
fire-place  and  boiler,  the  refult  was  20. i ;  or  20c>ybs  of  water,  were  boiled  with  lib.  of 
wood»  So  that  it  appears  that  theVatter  procefs  was  eighteen  times  more  economical  than  the 
former,  and  that  feventeen  parts  out  of  eighteen  of  the  fuel  were  confumed  to  no  purpofe  in  the 
iirft  experhnent*  With  regard  to  the  abtblute  quantity  of  heat,  the  author  deduces  firom  the  expe- 
riments related  in  Dr*  Crawford's  treatifc,  diat  lib.  of  charcoal  woul4  caufe  57. 6  lbs.  of  water  to 
l)on,  if  none  6f  the  heat  was  fuffered  to  efcape.  And  b^  Lavoifier's  experiments,  the  quantities 
of  he^it  generated  by  equ^  weights  of  charcoal  and  dry  oak  are  as  1089  to  600 ;  and  the  Count 
takes  it  to  be  nearly  true,  that  equal  weights  of  oak  and  of  dry  pine  wood  will  afford  equal  quan-* 
titles  of  heat.  Thefe  pofitfons  afford  th^  refult,  that  3i,74.1bs»  of  water  would  have  been 
brought  from  the  freezing  to  the  boiling  heatt  by  the  combuftton  of  lib.  cf  his  fuel.  It  follow^, 
therefore,  diat  in  the  method  cf  4>6i{mg  over -common  opcin  fire,  nearly  a8  parts  out  Of  29  of  the 
heat  are  loft ;  and  th:H:  in  the  Count's  edqperimenCB  the  abfolute  {ois  amounted  to  about  one>  third. 
When  the  generation  and  lofe  of  (learn,  the  conducing  power  of  the  materials,  and  the  quaiv> 
tity  of  heat  which  tnuft  neceffiirily  befi^iiired  to  pais  up  the  chimney  in  order  to  produce;  a  draf||, 
are  confidered,  it  may  be  doubted  whether  the  economy  of  fuel  can  be  carried  much  farther. 

As  the  fuel  of  this  country  confifts  of  coal  and  coke,  and  not  wood,  it  fcems  requifite  to 
Hate  their  comparative  powers  of  affording  heat  by  combuftion»   The  experiments  of  Lavoifier, 

Vou  IIL — July  i799>  -2  quoted 


i66 


Difcription  of  a  Furnace  and 


quoted  by  the  author>  give  the  following  proportions  *•    Equal  quantities  of  heat  are  produced 

by  the  combuftioii  of 

403  lbs  of  cokes      "^  f  1 7  of  cokes. 

600  —  of  pitcoal      i  ^^  .    ^^r.,^  J  10  of  pitcoal. 

600  —  of  charcoal  [  ^'  *"  "^^f""'  1  40  of  charcoal. 

1089  —  of  oak         J  ^  33  of  oak. 

If  pitcoal  had  been  ufed  inftead  of  pine-wood,  die  number  of  pounds  of  water  made  to  boil  by 
lib.  of  the  fuel  would  have  been  36,3  inftead  of  20,1 ;  and  as,  from  th^  experiments  of  Watt, 
it  is  eftablifhed,  that  nearly  five  and  a  quarter  times  the  quantity  of  heat  is  required  to  con- 
vert boiling  water  into  fleam  as  would  have  raifed  the  fame  water  from  the  freezing  to  the  boiling 
point,  it  will  follow,  that  the  heat  generated  in  the  combuflion  of  one  pound  of  pit-coal  ought 
to  afford  very  nearly  ylbs.  of  fteam. 

In  all  the  experiments  made  on  a  very  large  fcale,  with  brew-houfe  boilers,  rather  more  than 
one-half  the  heat  actually  produced  found  its  way  up  the  chimney  and  was  loft. 

The  fixth  chapter  of  this  efTay  contains  a  (hort  account  of  a  number  of  kitchens,  public  and 
private,  and  fire-places  for  various  ufes,  which  have  been  conftruded  under  the  direSion  of  the 
author,  in  different  places :  of  thefe  I  muft  neceflarily  forbear  to  fpeak  at  prefent. 

Fig.  I.  Plate  VIII.  is  a  front  view  of  the  new  boiler  of  the  brew-houfe  called  Neuheuiel 
(belonging  to  the  Eledor  of  Bavaria),  or  rather  of  its  fire-place  and  cover  (the  boiler  being  con- 
cealed in  the  brick-^irork).  The  infide  door  of  the  fire-place  is  here  reprefented  fhut ;  and,  ta 
order  that  it  might  appear,  the  outfide  door  is  taken  off  its  hinges,  and  is  not  (hown.  T|ie  two 
vaulted  galleries.  A,  B,  in  the  folid  mafs  of  the  brick- work,  on  the  right  and  left  of  the  fire- 
place (which  were  made  to  fave  bricks),  ferve  for  holding  fire-wood.  The  partition  walls  of 
the  fire-place  and  the  different  flues,  as  alfo  a  fedion  of  the  boiler,  are  reprefented  by  dotted 
lines.  The  fmall  circular  hole  on  the  left  of  the  fire-place  dior  is  the  glazed  window  opening 
into  the  fire-place,  by  which  the  burning  fuel  may  be  moft  acivantageoufly  ieen,  without  dif- 
turbing  the  current  by  any  opening  of  doOrs.  a  k  \s  the  wooden  curb  of  the  boiler :  r  ^  a 
platform  on  which  the  men  fhuid  when  they  work  in  emptying  the  boiler,  &c. :  efisz  plat- 
form which  ferves  as  a  pafTage  firom  one  fide  of  the  boiler  to  the  other.  This  platform,  which 
is  about  18  inches  wide,  is  12  inches  higher  than  the  other  phttforms,  in  order  that  the  openings 
g  and  hf  into  the  flues,  may  remain  free.  Thefe  openings,  which  are  opened  only  occafionally, 
that  is  to  fay,  when  the  flues  want  cleaning,  are  kept  cloied  by  double  brick- walls.  Thefe  walls 
are  exprefTed  in  the  following  figure. 

Fig.  2.  is  an  horizontal  fefiion  of  the  fire-place  at  a  level  with  the  bottom  of  the  boiler,  a^  a^ 
tf,^,  are  four  openings,  by  which  the  flues,  which  in  the  firft  arrai^ment  of  this  fire-place  went 
round  the  outfide  of  the  boiler,  were  occafionally  cleaned :  b  is  the  canal  by  which  the  fmoke  went 
off  into  the  chimney.    The  entrance  into  the  fire-place,  and  the  conical  perforation  in  the  wall 

*  Thefe  experiments,  which  were  communicated  to  Count  Rumford  bj  Mr.  Kirwao,  arc  to  be  found  in  the 
Mcmtirt  of  the  Paris  Academy  %  I  think  for  the  year  1781. 

of 


Boiler  fw  a  Brnvhoufe.  167 

^  •£  the  fire-place,  which  ferves  as  a  window  for  obferving  the  fire,  are  marked  by  dotted  fines. 
The  pofition  of  the  outfide  door  of  die  fire-place  is  marked  by  a  dotted  line,  c  d.  The  circular 
difliing-grate  is  feen  in  its  place ;  and  the  walls  of  the  flues  under  the  boiler  are  all  feen.  The 
crooked  arrows  in  the  flues  (how  the  diredion  of  the  flame. 

Fig*  3*  is  a  vertical  fedionof  the  boiler  reprefented  in  the  foregoing  fig.  i.  Thisfedion  is 
taken  through  the  middle  of  the  boiler  of  the  fire-place,  and  of  the  cover  of  the  boiler.  A  is 
the  a(h-pit,  with  a  fedion  of  its  regifter  door.  B  is  the  fire-place,  and  its  circular  di(hing.grate. 
C  is  the  entrance  by  which  the  fiiel  is  introduced,  with  fedlions  of  its  two  doors.  D  is  a  fpace 
left  void  to  fave  bricks.  £  is  the  boiler,  and  F  its  wooden  cover,  m  is  the  fteam  chimney, 
which  is  fumifhed  with  a  damper.  R  R  is  the  vertical  wall  of  the  houfe  againft  which  the 
brickwork  in  which  the  boiler  is  fixed  is  placed,  a  b  is  the  curb  of  timber  in  which  the 
boiler  is  fet.  The  manner  in  which  the  cover  of  the  boiler  is  conftrudled,  as  well  as  its  form, 
and  the  door  and  windows  which  belong  to  it,  are  all  feen  difti'ndUy  in  this  figure. 

Fig.  4*  is  an  horizontal  fefkion  of  this  fire-place  taken  on  a  level  with  the  bottom  of  the 
flue  which  goes  round  the  outfide  of  the  boiler,  in  which  flue,  before  the  fire-place  was  altered, 
die  flame  circulated.    The  flues  under  the  boiler  are,  in  this  figure,  indicated  by  dotted  lines. 

Fig.  5.  Is  an  horizontal  fe£tion  of  the  fire-place  of  the  brew-houfe  boiler,  at  a  level  with  the  top 
of  the  flues  under  the  boiler,  after  the  flue  round  the  outfide  of  the  boiler  had  been  flopped  up^  or 
rather  the  flame  prevented  from  circulating  in  it  This  figure  (hows  the  aAual  ftate  of  the 
fire-place  at  the  prefent  time.  The  crooked  arrows  (how  the  direction  of  the  flame  in  the 
flues. — Oj  bj  are  the  two  canals  (each  of  which  is  furni(hed  with  a  damper)  by  which  the  fmoke 
goes  off*  into  the  chimney ; — and  r,  r,  c,  r,  c,  r,  are  fix  fmall  openings  communicating  with  the 
flues,  by  which  the  flame  and  hot  vapour  can  pafs  up  into  the  cavity  on  the  outfide  of  the  boilery 
which  formerly  ferved  as  a  flue. 

Fig.  6.  is  a  front  view  of  the  afh-pit  door  of  this  brew-houfe  fire-place,  with  its  regifter.  This 
door  is  clofed  by  means  of  a  latch  of  a  particular  conftrud^ion,  which  is  (hown  in  the  figure.       \ 
Fig.  7.  is  the  door  without  its  regifter ; — and 
Fig.  24.  the  circular  plate  of  the  regifter  reprefented  alone. 

In  conllruSing  thefe  itgiftcr  doors,  and  in  general  all  iron  doors  for  fire-places,  great  and 
linall,  the  door  (hould  never  be  (hut  in  a  rabbet,  or  groove,  in  the  frame,  but  (houl4  merely 
fl3ut  down  on  the  front  edge  oftheframe^  which  edge,  by  grinding  it  on  the  flatfurfece  of  a  large 
flat  ftone,  fliould  be  made  quite  level  to  receive  it.  If  this  be  done,  and  if  the  plate  of  iron 
which  conftitutes  the  door  be  made  quite  flat,  and  if  it  be  properly  fixed  on  its  hinges,  die  door  ^ 
will  alwa]rs  (hut  with  facility  and  clofe  the  opening  with  precifion,  notwithftanding  the  efieds 
of  the  expanfion  of  the  metal  by  heat ;  but  this  cannot  be  the  cafe  when  the  doors  of  Hre-places 
are  fitted  in  grooves  and  rabbets.  Where  the  heat  is  very  intenfe,  the  frame  of  the  door  (hould 
be  made  of  fire-ftone  \  and  that  part  of  the  door  which  is  expofed  naked  to  the  fire  (hould  be  co. 
vered  either  with  a  fit  piece  of  fire-ftone,  faftened  to  it  with  clamps  of  iron,  or  a  fufficient 
number  of  ftrong  nails,  with  long  necks  and  flat  heads,  or  of  ftaples,  being  driven  into  that  fide 
<if  -the  plate  of  i  Fon  which  ibrms  die  door  which  is  expofed,  (hould  be  covered  with  a  body  about 

Z  2  *  two 


two  inches  ihlckof  ftrong  day,  mjxed  wid)  a  due  portion  of  coarfe  powder  of  broken  crucibles^ 
which  rnafs  will  be  beM  in  its  place  by  the  heads  of  the  nails,, and  by  the  projediing  ftaples.  This 
mafs  being  put  on  wet,  and  gently  dried,  the  cracks  being  carefully  filled  up  as  they  appear,  and 
the  whole  well  beaten  together  into  a  folid  mafs,  will,  when  properly  burned  on  by  the  h;:at  of 
the  fire,  form  a  Covering  for  the  door,  which  will  efFedluially  defend  it  from  all  injury  from  the 
fire;  aiid  the  door,  fo  defended,  will  laft  ten  tknes  longer  than  it  would  laft  without  this  defence. 
The  infide  doors  of  the  two  brew-boufe  fire-places  which  the  Count  fitted  up  at  Munich  are 
both  defended  from  the  heat  in  this  manner ;  and  the  contrivance,  which  has  anfwered  perfedl/ 
all  that  was  expe£tcd  from  it,  has  not  been  found  to  be  attended  with  any  inconvenience  what- 
ever. 

I  have  lately  feen  the  patterns  at  Count  Rumford's  for  cafting  a  regulating  door  of  his  inven- 
tion, which  poflTefTes  the  advantages  of  fimplicity,  cheapnefs,  andefFeft,  in  a»very  ftriking  de- 
gree. It  has  neither  hinges  nor  Hiding  groove :  it  clofcs  with  utmoft  precifioii ;  and  from  the 
very  fmall  quantity  of  work  it  requires  to  finifh  it,  the  price  ought  not  to  exceed  two  or  three 
killings.  I  am  not  at  liberty  to  anticipate  the  inventor,  who  will  communicate  it  to  the  public 
as  foon  as  this  can  be  nK)ft  effefiualiy  done,  xuunely,  by  direding  them  to  a  place  where  they 
■lay  fee  what  they  are.  to  imitate. 


4Ma^ 


V. 
Extra/fion  of  Sugar  from  CarrotSy  &c, — Experiments  on  Barytes  and  Strontites. 

Extras  of  a  Letter  from  Mr^  William  Henrt  of  Manchefiery  to  the  Editor^  dated 

June  7.0th ^  1 799* 


M- 


Y  friend,  Dodor  Pefchier  of  Geneva,  who.  is  now  at  Vienna,  fends  me  the  following  in- 
formation refpeding  the  extradion  of  fugar  from  carrots,  &c.  I  iubjoin  alfolbme  experiments 
of  my  own,  on  the  fulphate  and  Pruffiate  of  barytic  and  flrontian  earths. 

<'  Profeflbr  Jacquin  rafped  and  exprefled  4olbs.  of  roots  of  carrots  (daucus  carota).  The 
juice,  which  was  pretty  clear,  and  of  an  agreeable  tafb,  was  evaporated  to  the  confidence  of 
iyrup ;  clarified  with  fome  albumen  of- egg,  after  being  mixed  with  fbme  ounces  of  quick-lime  i 
and  filtrated.  After  cooling  a  few  days,  it  contained,  in  the  bottom  of  the  veflel,  (mail  cr}  llals^ 
which,  when  wafhed  in  cold  water,  were  white  and  diaphanous*  To  thefe  fucceeded  others  of 
a  yellow  colour.  The  whole  of  the  cryftals  amounted  to  12  oz. ;  they  Cafl^d  eza&Iy  like  the 
pureft  fugar,  and  preferve  their  drynefs  to  this  day.  There  remained  about  41b.  of  a  brown 
fugar  perfedUy  agreeable  to  the  tafle.  ' 

^^  Second  experiment.    Three  roots  of  beta  cycla  altiffima>  weighiog,  afbr  having  been 
peeled,  41b.  were  pounded  and  exprefTed.    The  juice  was  tUck,  mucilaginous,  and  fweet,  but 
4ifagreeably  mixied  with  the  tafle  of^turnips.    It  was  evaporated,  according  to  the  method  of 
Mr.  Acbard  of  Berlin,  without  any  addition,  and  flummed  at  intervals.    This  fcum  was  pro- 
duced 


Sngarfim  Carrots^  Bat.  btc.  169 

duced  by  the  alhumen,  which,  you  know,  is,  to  be  found  in  raoft  vegetables,  and  coagulates  at 
a  certain  degree  of  heat.  When  thus  cleared,  it  had  completely  loft  its  (harpnefs,  but  after 
ftanding  at  reft  for  fomc  days,  in  a  cool  place,  it  ihewed  no  tendency  to  cryftallize.  It  was 
then  evaporated  in  a  water-bath,  and  afforded  a  pafte  of  a  light  brown  colour;  that  deli- 
queiced  in  a  fhort  time,  and  refumed  the  conflftence  of  a  thick  fyrup,  to  the  weight  of  4 lb.     . 

**  Third  experiment  iilb.  of  the  fame  roots  were  expreiTed,  as  in  the  fecond  experiment, 
but  were  purified  as  in  the  firft.  They  gave  31b  of  a  clear  fyrup,  which  afforded  3  oz.  of  fmall 
cryftals  of  fugar,  of  a  pleafant  tafte^  The  remaining  fyrup  was  brown  and  very  fwcet.  It  is  to 
be  obferved,  that  as  thefe  experiments  were  made  in  the  fpring,  the  roots  had  already  begun  to 
fhoot,  and  contained  rather  more  mucilage  than  fugar.  It  is  neceffary,  alfo,  to  inform  you,  that 
the  little  plate,  affixed  to  the  work  of  M.  Achard,  reprefents  the  beta  vulgaris,  while  the  de- 
icription  is  that  of  beta  cycla  abtiffima,  which  is  very  different.  On  the  whole,  the  extraftion 
of  fugar  from  the  carrot  and  turnip,  on  a  larger  fcale,  promifes  to  become  an  objeA  of  profitable 
peculation. 

^  It  has  been  difcovered  lately,  that  the  water,  remaining  after  obtaining  ftarch,  contains  a 
large  quantity  of  fugar." 

I  know  not  whether  you  will  think  the  following  experiments  on  barytes  and  f^ontites 
worthy  of  a  place  in  your  journal 

The  analyfis  of  the  native  fulphate  of  ftrontites  from  the  neighbourhood  of  Briftol,  which  has 
been  fo  well  executed  by  Mr.  Clayfield,  eftablifhcs,  beyond  all  controverfy,  the  naturp  of  that 
compound.  If  any  teftimony  were  required  to  the  accuracy  of  Mr.  C.'s  experiments,  I  might 
ftate,  that  early,  laft  winter  I  read  to  the  Literary  and  Philofophical  Society  of  this  town,  an 
analyfis  of  the  fame  fubftance,  from  which  I  ai&gned  as  its  components,  in  100  grains,  414  of 
fulphuric  acid,  58^^  pure  ftrontites,  and  one-fourth  of  a  grain  of  water,  befides  a  fcarcely  not- 
able portion  of  iron.  Thefe  proportions  do  not  differ  more  than  a  quarter  of  a  grain  from  thofe 
ofMr.C. 

If  Mr.  Clayfield's  analyfis  be  imperfeft  in  any  refpe6t,  I  think  it  is  in  the  deficiency  of  proof 
diat  the  mineral  under  examination  contains  no  portion  whatibcver  of  barytes.  To  afcertain 
the  prefence  of  the  laftmentioned  earth,  Mr.  C.  poui:ed  on  the  precipitate  obtained  by  boiling 
riie  native  fulphate  of  ftrontites  with  carbonajtc  of  potaib,  "  a  quantity  of  muriatic  acid,  fuffi- 
cient  to  diffolve  only  a  few  grains  of  the  earth.  Had  any  barytes  been  prefent,  it  would  have 
been  taken  up  in  preference  to  the  ilrontites,  from  its  fuperior  affinity  for  the  acid;  the  folu- 
( tion,  however,  after  digeftion  for  feveral  hours,  ftill  cryflalli^d  in  needles,  and  afforded  ^ 
copious  precipitate  to  barytic  lime-water.'*  (Phil.  Journ.  III.  38.)  It  will  be  found,  however, 
that  on  the  addition  of  dilute  muriatic  acid  to  a  mixture  of  carbonates  of  barytes  and 'ftrontites^ 
a  portion  of  each  earth  is:  diffolved,  as  might  indeed  be  expend  from  ieveral  known  fa&s  re- 
>^ding  chemical  affinity,  which  (hew  that  facility  of  combination  and  ftrengtb  of  affinity  by^ 
SID  means  keep  pace  together.  At  a  certain  point  of  concentration^  the  muriatic  acid  even  dif« 
fiolvcs  ftrontites  in  pitference  to  barytes,  on  account  of  the  greater  AriubiUty  of  the  refulting 

compound* 


O 


lyo  Experiments  $n  Strenttan  arid  Barf tes* 

compound.-— The  method  by  which  I  examined  whether  the  mineral  under  examination  con« 
tained  barytes,  was  as  follows. 

1.  The  fpar  was  decompofed  by  digeftion  with  carbonate  of  potafh>  as  in  Mr.  Clayfield*s 
experiments.  The  fubilanee  thus  obta:ined,  confifting  of  the  earthy  part  of  the  mineral  com- 
bined with  carbonic  acid,  I  (ball  call  the  precipitated  earth. 

2.  Nitric  acid  was  gradually  diluted  with  water,  till  it  became  capable  of  diilblving  ftron* 
titcs  but  not  barytes  ;  for  to  diflblve  the  latter,  much  further  dilution  is  neceflary«>  The  pre- 
cipitated earth  was  wholly  diflTolved  by  this  acid,  which  would  have  left  undifiolved  any  portion 
6(  barytes. 

3.  Barytes,  in  a  pure  and  caufticftate,  according  to  Dr.  Hope  (Edinb.  Tran(a£t.  vol.  iv.), 
precipitates  ftrontites  and  all  other  earths  from  muriatic  acid.  I  expoTed,  therefore,  to  an  in-* 
tenfely  ftrong  fire,  a  portion  of  the  precipitated  earth}  and  thus  deprived  it  of  its  carbonic  acid 
fo  completely,  that  it  readily  diflblved  in  hot  water,  and  cryftallized  on  cooling.  Now,  if  the  pe« 
culiar  mineral  under  examination  contained  any  barytes,  this  watery  folution  of  its  pure  earthy 
part,  on  being  added  to  a  folution  of  die  precipitated  earth  in  muriatic  acid,  would  occafion  a 
reparation  of  ftrontites.  On  making  the  experiment,  however,  no  precipitation  took  place» 
which  (hows  that  the  watery  folution  contained  no  barytes,  but  confifted  of  pure  ftrontites 
only.  The  iame  hiSt  alfo  proves  that  the  muriatic  folution  contained  neither  lime,  magnefia^ 
alumine,  nor  any  of  the  metals,  any  one  of  which  would  have  been  precipiuted  by  the  ftrontitic 
water. 

The  following  experiments  are,  perhaps,  worth  relating,  as  they  fumifb  additional  proof  diat 
barytes  and  ftrontites  are  really  diftinA  and  peculiar  earths. 

Dr.  Hope,  and  I  believe  the  generality  of  writers  on  this  fubjed,  affcrt  that  barytes  (in  con- 
tradittinftion  to  ftrontites^  is  precipitated  from  muriatic  acid  by  the  Pruifiate  of  potafli.  But 
Mr.  Kirwan,  on  grounds  which  he  has  not  ftated,  teftifies  the  contrary.  **  Moft  earths,"  he 
obferves  (Elements  of  Min.  I.  3.),  **  are  foluble  in  fome  acid  or  another,  and  many  in  all 
acids  ;  theTruffian  alkali  can  precipitate  none  of  them  from  thefe  folutions ;  idiereas  it  preci- 
pitates all  metallic  fubftarices  except  platina  ftom  Acir  acid  folvcnts.  This  forms  a  diftindl  line 
o{  feparation  between  eartfis  and  metals.  The  exception,  formerly  made  in  favour  of  baryjic 
earth,  is  now  found  to  have  arifen  from  a  naftake."  As  the  decifion  of  this  queftion  is  of  fome 
importance,  from  its  influence  on  mineral  analyfis,  I  determined  to  (atisfy  mylelf  of  the  truth  by 
the  proper  experiments ;  the  relation  of  barytes  and  ftrontites  to  the  Pruffic  acid,  not  having 
'been  an  objeS  of  attention  either  with  Dr.  Hope,  M.  Klaproth,  or  MefT.  Pclletier>  Fourcroy, 
and  Vauquelin. 

1.  Relation  of  Barytes  to  the  Prujjic  Acii^ 

To  a  folution  of  cauftic  cryftallized  barytes  in  hot  water,  Pruffiate  of  iron,  which  had  been 
well  wa(hed  with  boiling  diftilled  water,  was  gradually  added,  iill  it  ceafed  to  be  diicoloured. 
The  folution  of  barytes  acquired  a  yellow  tinge,  refembling  that  of  Pruffialed  potaflu  It  was 
geritly  evaporated,  and  when  cold,  a  number'  of  cryftals  had  formed,  which  were.flightly  tinged 
<by  iron,  and  appeared  to  be  very  minute  rhomboidal  parallelopipeds. 

Thefe 


0 


Expirtmenis  §h  Strontian  and  Barytes.  171 

Thcfe  cry  ftals  were  fparingly  foluble  in  water,  4  oz,  of  which,  at  65^  Fahrenheit,  took  up  barely 
one  grain  ;  and  of  boiling  water,  each  ounce  diffolved  only  between  five  and  fix  grains.     The 
watery  folution  gave  a  precipitate  of  fulphate  of  barytes,  on  adding  fulphuric  acid,  and  of 
Pruffiated  iron,  with  the  folutions  of  that  metal.   In  a  low  red  heat,  the  iait  was  foon  changed 
into  a  black  mafs,  confiding  of  carbonate  of  barytes  and  charcoal.    The  cryftals  difiblved 
readily  in  diluted  nitric  and  muriatic  acids,  apparently  without  decompofition,  for  the  folutions 
precipitated  falts  of  iron.    They  were  decompofed  by  carbonate  and  fulphate  of  pouih»  a 
double  exchange  of  principles  enfuing. 
.  Part  of  the  precipitate,  obferved  on    adding  the  Pruffiate  of  potafli  to  muriated  barytes,   is 
doubtlefs  often  occafioned  by  the  prefence  of  fulphate  of  potafh  in  the  Pruffiatcd  alkali  j  an 
adulteration,  which  it  is  difficult  entirely   to  avoid  j   but  that  a  double  elective  affinity  is  . 
exerted  between  the  two  falts,  clearly  appears  on  examining  the  precipitate.    After  being 
repeatedly  wafhed  with  diftilled  water,  muriatic  acid  will  be  found  to  diflblve  the  greater  part 
of  it ;  and  the  folution  of  the  precipitate,  in  this  acid,  betrays  the  prefence  of  Pruffiate  of  ba- 
rytes, on  applying  the  proper  tells.     It  may,  therefore,  be  received  as  an  eflablifhed  fa(5t^  that 
an  infoluble,  or  difficultly  foluble  Pruffiate  of  barytes  is  formed,  on  adding  Pruffiate  of  jj^taSh 
to  the  muriated  earth,  a  property  in  which  barytes  differs  from  all  other  earthy  bodiei,  and 
refembles  the  metals  :  the  fimple  affinity  of  potafh  for  Pruffic  acid  is  fuperior  to  that  of  ba- 
rytes; for  cauflic  barytes  does  not  precipitate  a  perfe£lly  pure  Pruffiate  of  potafh.     Barytes  ^j|^  « 
attrads  Pruffic  acid  more  powerfully  than  lime,  for  Pruffiate  of  lime  is  decompofed  by  pure 
barytes  ;    the  order  of  thefe  affinities,  I  believe,  has  not  before  been  afcertained. 

2.  Relation  of  Strontites  to  the  Pruffic  Acid, 
A  folution  of  pure  cryflallifed  ftrontites  deprives  Pruffiate  of  iron  of  its  tinging  acid ;  but 
the  folution  of  Pruffiated  flrontites  is  much  lefs  difpofed  to  cryflallife  than  the  homologous 
barytic  fait.  Indeed  I  have  repeatedly  evaporated  folutions  of  Pruffiated  {lr9ntites  very  low, 
without  having  been  able  to  obtain  any  cryftals.  I  therefore  expelled  from  one  portion  the 
whole  of  the  water  by  a  gentle  heat ;  the  dry  mafs  thus  obtained  difl!blved  readily  in  water  at 
65*,  an  ounce  of  which  took  up  120  grains,  and  even  then  did  not  appear  to  be  faturated: 
but  having  no  more  of  the  fait,  I  was  prevented  from  afcertaining  its  tx^&,  folubility.  The 
dry  fait  does  not  deliquiate  :  in  its  other  properties,  it  refembles  Pruffiated  barytes. 

A  folution  of  cauftic  ftrontites  does  not  precipitate  Pruffiated  lime,  as  barytes  does ;  ftill, 
however,  a  decompofition  probably  takes  place,  but  is  prevented  from  being  apparent  by  the 
folubility  of  the  new  compound.  This  may,  alfo^  be  the  cafe,  when  muriated  ftrontites  is  added 
Co  Pruffiate  of  potafh,  or  of  lime. 

Pure  barytes,  when  added  to  Pruffiated  ftrontites,  occafions  a  precipitate,  but  a  much  left 

abundant  one,  than  might  be  expe£led ;  hence  it  is  probable  that  the  affinities  of  thefe  two 

earths  for  Pruffic  acid  are  nearly  equal  in  ftrength,  as  Dr.  Hope  has  (hewn  they  are,  with 

fcfpedt  to  carbonic  acid. 

Dr.  Pefchier  acquaints  me,  that  die  fulphate  of  ftrontites  abounds  in  Syria  and  in  Hungary, 

but  not  the  carbonate. 

Concerning 


lya  Tltrmmetrlcat  Flrfi  nuvtr$. 


V.I.    . 

Concerning  thofe  perpetual  Motions  which  are  producible  in  Machines^  by  the  Rife  and  Fall  of 
the  Barometer y  or  the  Thermemetrical  Variations  of  the  Dimenjions  of  Bodies.    W.  N. 


s 


(Concluded  from  p.  izS.) 


UPPOSE  this  apparatus  to  be  put  together  at*  a  certain  temperature  in  thie  day-time;  and 
that  in  the  night  the  temperature  becomes  colder;  in  this  cafe,  the  curvature  of  all  the  bars 
will  diminifh)  and  the  diftance  between  A  and  B  will  be  increafed  by  the  aftion  of  the  inter*« 
mediate  fpriiig :  but  as  the  plate  A  is  prevented  by  the  click  C  from  receding,  the  plate  B 
will  be  pu(hed  forward,  and  the  interior  cylinder  will  gather  a  certain  number  of  its  teeth  upon 
the  click  D.  The  next  day^  when  die  temperature  again  rifeS)  all  the  expanfion  bars  will 
bend)  and  the  fpace  i3etween  A  and  B  will  be  diminilhed ;  this,  however,  cannot  happen  by  the 
motion  of  B,  which  is  held  faft  by  the  click  D.  The  external  part  will,con(equently,  be  now 
carried  forward,  and  will  aA  upon  the  apparatus  E:  a  fecond  lowering  of  die  temperature,  by 
whatever  caufe,  will  occafion  the  interior  part  again  to  advance)  and,  in  this  manner,  the 
accumulations  of  force  may  be  incefTantly  reiterated* 

Experience  muft  determine  how  far  the  properties  of.  diefe  compound  bars  may  be  changed 
in  the  courfe  of  time**  It  feems  probable,  that  the  mere  changes  communicated  by  tbe 
atmofphere,  could  fcarcely  produce  any  fenfible  effed;  and  vi^ether  this  effed  would  be 
detrimental  to  the  general  refult,  may  alfo  be  queftioned*  Confiderations  of  this  nature,  lead 
to  the  enquiry,  whether  our  obje£l  may  not,  with  equal  facility,  be  obtained  by  the  dired  pufll 
or  pull  of  bars  of  metal,  as  in  the  gridiron  {5endulum,  or  that  of  Ellicottf. 

If  a  fucceffion  of  bars  of  brafs  were  difpofed  round  a  cylindrical  face  of  lefs  expanfible 
metal,  fo  as  to  form  an  helical  line  from  the  one  end  to  die  other;  or,  otherwife,  if  we  fuppofe 
a  brafs  clock  chain,  with  a  right*lined  edge,  to  be  wrapped  round  fuch  a  cylinder ;  or  again,  if, 
inftead  of  the  cylinder,  we  fuppofe  tbe  chain  to  pafs  over  a  fuccei&on  of  rollers,  whedier  dif-« 
pofed  in  a  cylindrical  fyftem,  or  according  to  the  form  of  a  puUy,  the  refult  will  be  the  fame; 
that  is  to  (ay,  the  chain  will  contrail  and  expand  about  the  ten-thoufandth  part  of  its  lengdr^ 
for  every  ten  degrees  of  Fahrenheit's  thermometer.  In  die  way  of  rough  eftimate,  let  US| 
therefore,  aiTume  a  cylinder  of  caft-ironi  one  foot  in  diameter*  and  one  foot  in  lengdi, 
having  a  groove  turned  in  its  furface,  like  a  fcrew,  with  twelve  turns  in  the  inch,  for  the 
purpofe  of  lodging  a  iyftem  of  fridion  rollers  to  receive  the  brafs  chain,  wrapped  round  it. 
Such  achain:(,  cpnfifling  of  144  turns,  would  meafure  450  feet§,  and  would  contracEl  nearly 
o,S4  inches  for  every  10  degrees,  or  one-twentieth  of  an  inch  for  each  degree  of  change  of  tem- 
perature ;  but  as  the  cylinder  itfelf  contradU,  the  whole  effedl  will  be  fomewhat  lefs  than  half 
diat  quantity ;  that  is  to  iay,  each  degree  of  the  thermometer  will  be  one-fortieth  of  an  inch; 


*  Philof.  Journal,  I.  62.  f  Ibid,  p.  59,  60^ 

:J;  And  would  coH  about  25!.  {  For  pyrometrical  data,  fee  Philof.  Journal,  I«  58. 


The 


Thermm-trical  anJ  Baromitrica!  Firft'mwers.  173 

The  philofophical  world  is  aware,  that  hygrometers^  have  been  made,  on  this  priiiciplei 
with  cat-gut,  hair,  whalebone,  and  other  materials.  It  feems  probable,  that  the  firft  gf  theCe 
fubftances  would  exert  confidcrabls  force  as  2  firft-movcr,  but  it  would  fcarcely  prove  durable ; 
and  what  is  ftill  worfe,  the  variations  of  moifture  in  the  atmofphere  are  little  fuited  to  operate 
upon  machinery  prefcrved  in  a  cafe  in  an  apartment. 

If  the  increafe  of  the  fpace  moved  through  by  the  expanfion  of  metals  upon  the  principle  of 
£lHcott's  pendulum,  ihould  be  adopted  indcad  of  the  compound  bars  in  fig.  4,  the  projed 
of  fig.  5,  may  be  followed.  A  bar  of  fteel,  A  K,  is  fixed  befide  a  bar  of  brafs  B  I,  the 
joinings,  I K,  being  inflexible;  but  thcfe  at  A,  B,  in  the  lever  A  F,  h^ing  jointed,  the 
difference  of  expanfion  between  the  two  metals  will  be  magnified  at  F,  in  the  proportion  of 
A  F  to  A  B.  The  lines,  L  C,  G  D  £,  reprefent  a  fecond  combination  of  the  fame 
kind,  in  which  the  point  G  will  have  a  fimilar  and  equal  modon  to  that  of  F,  but  the  bar 
£  L,  being  prolonged  to  F,  fo  as  to  bear  upon  the  lever  E  F,  the  whole  of  the  fecond 
combination  will  be  pufbed  forward  by  the  expanfion  of  the  firft;  on  account  of  which,  the 
oiotion  of  G  will,  in  fa<Sl,  be  double  that  of  F;  by  the  addition  of  a  third  combination,  the 
motion  will  be  tripled,  &c.  A  fufiicient  number  of  thefe,  properly  placed  in  the  cavity,  be- 
tween the  two  cylinders,  fig.  4,  would  afford  the  fame  confequences  ^  but  it  may  be  doubted, 
whether  any  contrivance  of  this  laft  kind  could  afford  the  fame  power  in  as  fmall  a  fpace  as 
that  occupied  by  the  compound  bars. 

I  ihall  now  proceed  to  form  an  eftimate  of  the  quantities  of  force  communicated  by  thefe 
(everal  contrivances. 

The  apparatus,  fig«  j,  plate  VI.  or  barometrical  clock,  is  driven  by  a  force  which  may  be 
ellimated  in  its  annual  quantity  from  the  fum  of  the  deviations  of  the  barometer  taken  from  a 
Meteorological  Journal,  fuch  as  that  in  the  Philofophical  Tranla<aions ;  together  with  the 
quantity  of  mercury  fo  moved,  which  may  be  derived  from  the  dimenfions  of  the  furfaces  in 
the  tube  and  bafon.  From  thefe  variations,  feverally,  muft  be  taken  the  quantity  of  what 
mechanics  call  lofl  time,  or  the  ineffectual  movement  between  the  dired  and  retrograde  aflions 
on  the  machinery.  The  whole  power  will  be  meafured  by  the  entire  column  of  variation^ 
fuppofed  to  defcend  through  half  its  height;  for  this  will  be  the  cafe  when  a  perpendicular 
tube  empties  itfelf  by  the  defcent  of  any  fluid  contained  in  it.  I  have  not  taken  the  trouble 
to  colled  thefe  elements ;  but  it  may  eafily  be  imagined,  that  the  fum  of  all  the  variations 
during  the  year,  would  amount  to  no  great  quantity.  I  underftand,  from  the  ingenious 
conftru£lor  of  this  apparatus,  that  the  accumulated  power  was  not  fuflicient  to  allow  the 
clock  to  be  maintained  by  a  force  equal  to  that  which  drives  a  common  watch,  namely,  fix 
ounces,  with  the  daily  fall  of  twelve  inches. 

In  the  inveftigation  of  the  power  of  expanfion,  in  fig.  4,  a  variety  of  curious  objeds  of 
phyfical  and  mathematical  refcarch  offer  themfelves  to  our  confideralion.  In  a  former  part 
of  this  Journal*,  it  has  been  (hewn,  that  the  curvature  affumed  by  a  ftraight  compound  bar^ 
having  each  of  its  parts  uniformly  thick,  will  be  circular  \  whence  it  follows,  from  the  nature 

•  I.  62. 
Vol.  IIL— July  1799.  A  a  of 


'  tj4.  On  tie  Power  (f  Expanjion'-hars  as  Fir/t-moverf, 

of  verfed  fines  of  fmall  arcs^  that  the  diftance  A  B,  fig.  2,  will,  ceteris  parihesy  he  as  the 
fquare  of  C  A;  and  it  (hould  feem  as  if  a  confiderable  advantage  might  be  derived  from  ufing 
the  whole  length  of  the  bar,  as  in  that  figure,  2,  inftead  of  the  two  half-lengths  in  fig.  3.  But 
it  muft  be  confidercd,  that  the  eflFecl  of  hammer- hardening  the  lower  part,  and  wire-drawing 
the  upper,  of  the  compound  bar  C  A,  is  twice  as  great  at  C,  fig.  2,  as  it  is  at  C,  in  fig.  3^ 
and  is  fliewn  in  the  greater  fpring,  or  jrielding  of  the  parts ;  and  that  the  a6lion  at  A,  in  this 
figure,  is  doubled  at  the  oppofite  extremity  of  the  bar : — fo  that  upon  the  whole,  the  a<5iion  at  A,. 
On  account  of  the  fhort  lever  A  C,  fig.  3,  being  twice  as  powerful  as  that  at  A,  in  fig.  2,  and 
being  exerted  through  the  (pace  A  B,  fig.  3,  of  one-fourth  part  of  the  fpace  A  B,  in  fig.  2, 
will  be  half  the  adion  at  the  end  of  fig.  2.  But  as  both  extremities  of  the  bar  are  made  to 
aft  in  fig.  3,  the  whole  of  its  aftion  will  be  precifely  equal  to  that  in  fig.  2.  The  combi-^ 
nation,  fig.  3,  appears,  therefore,  to  be  preferable  on  account  of  its  convenient  figure  only. 

It  may  alfo  be  queftioned,  whether  thefe  bar^  (hould  be  made  extremely  thin,  or  the  contrary^ 
If  they  be  very  thin,  the  efFeft  of  the  reaftion  being  equivalent  to  a  pull,  or  pu{h  endways 
upon  the  bar,  which  is  greater  than  the  readion  itfelf,  in  the  proportion  of  the  length  of  the 
bar  to  its  half  thicknefs,  it  may  eafily  be  imagined,  that  the  texture  and  cohefion  will  be  moft 
ftrongly  aflFefled ;  but,  on  the  contrary,  if  the  bar  be  very  thick,  the  eflFe£k  fropa  change  of 
temperature  may  refolve  itfelf  intirely  into  an  aftion  upon  the  parts  near  the  contiguous 
furfaces  without  producing  any  flexure  at  all.  It  appears,  therefore,  that  there  is  a  thickne& 
which  is  praSically  better  than  any  other.;  but  what  this  thicknefs  may  be,  remains  to  be 
determined  by  trials.  As  the  quantity  of  motion  is  inverfely  as  the  thicknefs  (Philo& 
Journal,  I.  576),  and  the  force  direftly  as  that  thicknefs,  it  muft  follow,  that  the  quantity  of 
mechanic  efl^eft  in  all  fimilar  bars,  neither  extremely  thick,  nor  extremely  thin,  will  be  the 
fame  upon  equal  changes  of  temperature.  I  fhould  give  the  preference  to  thin  bars,  not  fo 
much  reduced  as  to  have  any  perceptible  fpring. 

If  the  fig.  4.  be  fuppofed  of  fuch  dimenfions,  as  that  the  circular  arc  ftruck  through  the 

» 

middle  parts  of  all  the  bars  might  be  three  feet  in  length,  and  the  bars  were  each  fix  inches 
long  in  the  radial  direction,  with  a  thicknefe  nearly  equal  to  that  of  the  fecond  experiment 
related  at  the  laft-quoted  article  of  our  Journal ;  the  fpace  moved  through,  by  each- bar,  upon 
an  alteration  of  146  degrees,  would  be  about  0,05  inch,  or  half  a  tenth :  bat  300  of  thefe  bars 
might,  with  eafe,  be  contained  in  the  circular  fpace  of  three  feet,  and  thefe  would  produce  a 
motion  of  fifteen^  inches  by  the  fame  change  of  temperature,,  or  one-tenth  of  an  inch  for 
every  degree  of  Fahrenheit.  In  order  to  determine  the  force  with  which  this  change  oft 
pofition  would  be  afFe&ed,  we  are  in  want  of  fome  experiments  on  the  expanfions  of  metals* 
It  is  generally  fuppofed  that  a  rod,  or  wire,  will  contraft  or  dilate,  by  change  of  temperature, 
in  the  £une  manner,  whether  it  be  at  perfeft  liberty  to  move  horizontally,  or  be  made  to 
fupport  a  weight  hung  from  its  extremity,  or  placed  on  its  upper  end.  This  is,  in  fad,  fup-^* 
pofed  to  be  the  cafe  in  the  eftimates  for  conftrufting  gridiron  pendulums,  and  if  it  were« 
ftriiSly  true,  the  power  of  this  wheel  would  be  conftantly  equal  to  the  reaftion  againft  which  ir 
ibould  be  exerted.  But  it  would  be  to  little  purpofe  to  ioftitute  a  calculation  upon  data  afTumed 


Thermometricai  Firft^mavers*    Dying.  ijS 

at  random:  I  (hall  therefore  only  remark,  that  the  power  of  this  wheel  is  very confiderable, 
and  may  be  cncreafed  almoft  at  pleafure,  by  enlarging  the  dimcnfions  of  the  bars,  in  die 
di region  parallel  to  the  axis  of  the  cylinder. 

Whatever  queftion  there  may  be,  with  regard  to  the  force  and  durability  of  this  fyftem  of 
bars,  neither  of  which  I  am  difpofed  to  doubt,  there  can  be  fcarcely  any  with  regard  to  the 
fpiral  chain  round  the  cylinder.  The  direft  cxpanfion  and  contraftion  of  metals  is  certainly 
very  powerful,  and  was  (hewn  in  a  ftriking  manner  by  the  Rev.  Mr.  Jones  inan  experiment 
related,  if  my  memory  be  correfl:,  in  George  Adams's  Philofophical  Lectures.  He  hung  a 
very  heavy  weight  to  the  longer  end  of  a  lever,  the  ihorter  arm  of  which  preffed  upwards 
againft  the  longer  arm  of  another  lever,  and  the  (horter  arm  of  this  laft  was  fupported  by  a 
rod  of  metal.  By  this  mechanical  arrangement,  it  will  be  underilood,  without  difficulty,  that 
a  very  flight  motion  of  the  arm  which  bore  upon  the  metal,  might  be  attended  with  a  very 
confiderable  motion  of  that  extremity  which  fupported  the  weight ;  and  the  dimenfions  were 
fuch,  ttiat  this  was  in  fad  the  cafe.  The  flame  of  a  candle  applied  to  the  bar  of  metal  caufed 
it  to  expand,  and  carried  up  the  load  without  difficulty. 

Hygrometric  contractions  and  dilatations  are  known  to  be  performed  with  immenfe  force ; 
but  want  of  durability  in  the  materials,  and  the  difficulty  with  regard  to  expofure,  which  has 
been  already  mentioned,  feem  to  forbid  the  practical  u(e  of  this  power  for  the  purpofes  to 
which  our  attention  is  now  direded. 

The  contrivance,  fig.  5,  may  be  confidered  as  effe£hia!  j  but  the  objeftions  which  have  been 
made  to  Ellicott's  pendulum,  are  ftill  more  ftrongly  applicable  to  this,  namely,  that  the 
fiidtion,  the  wear,  and  the  irregular  aAion  of  the  joints,  muft  be  hurtful  to  the  general  efFeft. 


VII. 

Effays  on  the  Art  of  Dyings  by  Means  of  the  Solutions  ofTin^  and  the  coloured  Oxides  of  that 

Metal.     By  J.  M.  Haussman^* 


T, 


HIS  memoir  of  Citizen  Hauflinan  contains  the  refults  of  his  numerous  experiments  on 
the  folutlons  of  tin,  and  the  oxydes  of  that  metal ;  refults  which,  as  well  as  the  obfervations 
of  the  author,  are  very  interefting^  not  only  with  regard  to  the  improvement  of  the  art  of 
dying,  but  likewife  with  regard  to  our  fcientific  knowledge  of  the  diflFerent  degrees  of  the 
oxygenation  of  metals,  the  union  of  their  oxydes  with  their  folvents,  and  the  furcompofitions  of 
which  thofe  oxydes  are  fufceptible. 

The  author  commences  his  paper  by  announcing,  that  fince  the  time  of  his  refearches  con- 
cerning the  Turkey  red,  of  which  a  defaiption  is  inferted  in  the  twelfth  volume  of  the  An- 
nales  de  Chimie,  he  has  difcovered  a  red  which  is  no  lefs  fimple  than  beautiful  and  (olid,  the 
procefs  of  which  he  intends  fpeedily  to  publiih. 

.  *  Abftraft  from  the  memoir  of  the  authof  bearing  the  fame  title,  by  C.  A.  Prieur,  in  the  Annalcs  dc 
Chimie,  XXX,  15,  of  which  the  prefent  article  is  a  tranflatioQ. 

A  a  a  He 


9 

1  j6  Ontbi  Art  rf  Pytng  by  eibured  Oxydes  of  Tin. 

He  then  proceeds  to  give  an  account  of  his  experioients,  concerning  the  means  of  com* 
bining  the  colouring  matter  of  madder,  cochineal,  and  all  the  feveral  dying  drugs,  with  tin,  in 
order  to  fix  them  immediately  on  piece-goods,  in  the  way  of  folution  and  precipiution. 

His  experiments  were  made  on  the  folutions  of  tin,  by  the  nitro-muriatic,  muriatic,  ful- 
phuriCy  aiid  acetous  acids,  and  by  potafh;  and  he  mixed  the  colouring  decodlions  of  plants,  in 
fome  inflances,  with  the  acid  folutions;  in  others,  with  the. oxydes  precipitated  from  them ; 
or,  otherwife,  he  re-diflblved  in  alkali  ^e  oxydes  already  coloured.  The  following  is  a 
fummary  of  the  principal  circumftances  and  efFe£is  of  thefc  operations. 

When  the  fluids  do  not  immediately  afford  a  precipitate,  he  caufes  it  to  take  place  by  im- 
merfing  a  piece  of  filk,  cotton,  or  woollen.  The  precipitation,  in  fome  inftances,  takes  place 
by  the  fimple  mixture  of  the  two  liquids,  and  the  refult  confifts  of  oxydes,  coloured  accord* 
ing  to  the  nature  ^f  the  vegetable  fubftance.  Thefe  coloured  oxydes  appear  likely  to  b^ 
ufeful  in  painting.  In  other  experiments  h^  forms  thefe  coloured  powders,  by  firft  precipitating 
the  oxyde  of  tin  from  its  acid  folution,  by  the.  mere  addition  of  water;  and  the  edulcorated 
oxyde  feizes  part  of  the  colouring  matter  from  the  tinfturc  in  which  it  is  plunged,  Laftly, 
theie  coloured  oxydes  being  diiTolved  by  potafh,  and  the  fluffs  impregnated  with  the  folution^ 
the  colouring  matter  afterwards  become  fixed,  either  by  fimple  expofure  to  the  air  or  by» 
immerfion  in  an  acid  folution  of  tin  or  of  aluminej  according  to  the  obje£l  propofed  by  the 
operator. 

The  colours  which  are  produced  differ  in  kind,  in  (hade,  in  b/ightnefs,  -and  in  folidity^ 
from  various  caufes,  namely,  the  fpccies  of  vegetable,  the  kind  of  acid,  and  the  oxydation  of 
the  tin  ;  the  portion  of  acid,  or  alkali,  which  may  exifl  in  {be  precipitate,  according  to  the 
choice  of  the  operator;  the  greater  or  lefs  proportion  of  water  in  the  folutions  ;  the  other  <nr- 
cumflances  of  manipulation ;  or  the  feveral  ingredients  which  may  have  been  employed. 

Each  acid  differs  principally  by  the  degree  of  oxydation  to  which  it  is  difpofed  to  carry  the 
tin.  The  nitro*-muriatic  acid  being  capable  of  variation  in  its  dofe  of  oxygen,  is,  on  this  ac- 
count, more  or  lefs  proper  to  advance  the  oxydation  of  the  metal.  The  oxydation  is  alfo  more 
perfeft,  if  the  folvent  be  more  concentrated,  or  if  the  a£lion  of  heat  be  added,  or  if  the  fblutioa 
be  expedited,  by  adding  a  confiderable  quantity  of  the  metal  at  one  time.  The  oppofite  con- 
ditions are  attended  with  the  contrary  effed.  In  order  to  regulate,  at  pleafure,  the  greater  or 
lefs  oxydation  of  the  metal,  and  in  fome  meafure  at  the  will  of  the  operator,  it  will  be  fufEcient, 
if,  to  a X nitro-muriatic  folution  of  tin,  there  be  added  a  certain  quantity  of  the  muriatic  folu- 
tion of  the  fame  metal ;  for  this  lafl  may  eafily  be  obtained  at  the  lead  po(&ble  degree  of  ox« 
ydation. 

'  It  is  a  well-known  fsuft,  that  the  fpontaneous  progrefs  of  the  oxydation  of  the  folutions  of 
tin,  or  the  addition  of  water,  in  fufficient  quantity,  caufe  the  Reparation  of  a  precipitate.  This 
ctEcSt  maybe  prevented  when  neceflary,  by  leaving  of  adding  an  excefs  of  a^id  to  the  folution; 
or  by  adding  a  quantity  of  the  muriatic  folution.of  tin,  which  has  the  property  of  fupporting  a 
much  greater  quantity  of  water  v^ithout  precipitation }  or,  lafllyi  by  adding  muriate  of  fbda> 

or 


y 


On  the  Art  of  Dying  Ij  coloured  Oxydes  of  Tin*  177 

or  any  other  muriatic  fait,  the  efFe£t  of  which  feems  to  be,  that  they  (aturate  the  excefs  of 
water  which  would  elfe  have  occafioned  precipitation. 

Xo  haften  the  muriatic  folution  of  our  metal,  it  is  advantageous  to  fprinlcle  it  with  the  con- 
centrated acid,  and  then  leave  it  expofed  to  the  air.  The  furface  of  the  metal  becomes  oxyded 
with  fuch  rapidity,  that  a  fenfible  heat  may  be  produced  \  arifmg,  no  doubts  from  the  caloric 
taken  from  the  oxygen  gas  abfprbed  from  the  atmofphere. 

The  muriatic  folution  of  tin,  when  concentrated,  affords  many  cryftals  at  the  temperature 
of  ice,  and  thcfe  cryftals  are  permanent  in  a  cold  place.  The  heat  of  thirty  or  forty  degrees 
above  zero  (q.  of  Reaumur?)  liquifies  them*  When  difTolved  in  water,  they  afford  a  folution 
of  tin,  which  may  be  ufed  as  occafion  requires.  This  folution  becomes  oxyded  to  the  maximum 
(and  will,  confequently,  produce  different  efFcfts  on  the  colouring  fubftances)  if  it  be  left 
expofed  for  a  certain  time  to  the  air,  the  contact  being  favoured  by  an  extenflve  furfoce. 

The  oxyde  of  tin,  precipitated  from  its  muriatic,  or  nitro-muriatic  folution,  by  an  alkaline 
carbonate,  may,  if  not  too  much  oxyded,  be  very  eafily,  and  without  decompofition,  diffolved 
in  the  diluted  nitric  or  fulphuric  acids,  and  alfo  in  the  acetous  acid.  Thefe  folutions  producey 
with  colouring  fubftances,  (hades,  which  are  more  efpecially  governed  by  the  oxj^tion  of  the 
tin,  and  are  difpofed  to  change  more  or  lefs  fpeedily  in  the  air,  by  a  fuperoxydation  of  the 
metal,  and  according  to  the  nature  of  the  folvent.  The  fulphuric  acid  accelerates  this  effect 
more  than  the  nitric,  and  the  acetous  acid  the  mofl  rapidly  of  any  ;  which  circumfl^nce  (hews 
that  the  acetic  folution  of  tin,  if  it  be  required  to  be  kept  without  fpbntaneous  precipitation^ 
muft  be  preferved  in  well-clofed  bottles ;  and  that,  on  this  account,  it  would  be  preferable  to 
the  muriatic  folution  for  eudiometric  elTays. 

The  difpofition  of  the  colon  red  oxydes  of  tin  to  change  their  (hade  by  fuperoxygenation  from 
the  air,  appears  to  depend  on  the  circumAance  that  diey  retain  a  portion  of  the  acid  folvent* 
If,  on  the  contrary,  they  (hould  retain  a  portion  of  alkali,  the  (hade  is  different,  and  continues 
fixed  in  its  firft  ftate.  Thefe  precipitates  do  not,  however,  appear  to  unite  with  the  carbonic 
acid,  whether  it  be  that  this  acid  has  very  little  attraction  for  the  oxyde  of  tin,  or  whether,  a$ 
is  more  probable,  that  the  colouring  fubflances  exclude  it.  > 

A  very  remarkable  phenomenon  takes  place  in  thefe  changes  of  (hade,  by  the  degree  of  ox- 
ydation ,  when  the  infufion  of  cochineal  is  made  ufe  of:  the  leaft-oxyded  precipitates  are  of  a 
violet  colour,  which  by  expofure  to  the  air  becomes  more  or  lefs  fpeedily  converted  into  beautif* 
ful  carmines.  Ammoniac  caufes  them  to  approach  fomewhat  towards  crimfon;  but  they  prcr 
ierve  their  primitive  colour,  and  are  even  more  beautiful  when  the  ammoniac  has  evaporated. 
Jf  this  alkali  were  employed  upon  the  carmine  red  produced  by  precipiution  from  the  nitror 
muriatic  acid,  the  new  (bade  would  be  brown,  and  would  not  recover  its  original  luftre. 

In  general  this  kind  of  colours  depends  on  (everal  complicated  circumftances :  when  applied 
on  piece-goods,  they  rcfift  the  action  of  acids  better  than  that  of  the  air  and  the  fun.  They 
become  ftill  more  unchangeable  by  fubftituting,  inftead  of  the  nrtro-muriatic  folution  of  tin,  that 
made  with  muriatic  acid,  or  a  mixture  of  both*  The  coloured  oxydes  appear  likewife  to.gain 
both  in  folidity  and  brilliancy  when  they  are  prepared  by  a  folution  of  which  the  acid  is  not  ca- 
pable 


fji  Oh  the  Art  of  Dying  by  coloured  OxyJei  of  Tin. 

fable  of  decompofition,  and  in  which  the  oxygen  is  aflForded  to  the  metal  by  the  decompofi* 
tion  of  water.  The  muriatic  acid,  and,  which  is  flill  better,  die  ac4tous  acid,  afford  this  ad- 
vantage. 

The  phofphoric,  oxalic,  gallic,  and  tartareous,  acids  prefented  no  valuable  properties  with  re- 
gard to  the  produftion  of  thefe  colours.  The  precipitates  formed  by  the  urtlon  of  thefe  acids 
with  the  oxyde  of  tin  do  not  difcolour  the  infufion  of  cochineal. 

The  quantity  of  water  which  may  be  ufed  contributes  likewife  to  the  greater  or  Icfe  intimate 
combination  of  the  oxyde  of  tin  with  colouring  matters,  and  modifies  the  (hade  which  is  af^ 
forded.  For  example,  in  the  produftion  of  the  carmine  oxyde  by  the  infufion  of  cochineal,  too 
little  water  afFords  a  dull  colour,  and  too  much  prevents  the  metallic  oxyde  from  acquiring  co- 
lour enough  ;  fo  that  it  may  even  be  completely  difcoloured  by  repeated  wafliing. 

After  having  given  a  variety  of  intercfting  details  refpedling  the  coloured  oxydes  of  tin,  and 
carefully  related  theefTential  conditions  for  producing  each  of  thefe  oxydes  in  particular,  the  au- 
thor purpofes  to  ufe,  as  a  mordant  in  dying,  the  folution  of  the  acetite  of  tin,  which  he  prefers 
obtaining  by  the  cold  mixture  of  the  aqueous  folutions  of  the  acetite  of  lead,  and  the  muriate  of 
tin  in  cryftals,  in  order  that  the  acetous  folutions  of  tin  thus  obtained  may  be  very  concentrated, 
and  loaded  with  the  metal  We  cannot  do  better  in  this  place  than  copy  the  words  of  the 
author,  which  will  explain  the  nature  of  the  operation,  its  importance,  and  the  precautions  it 
Inquires. 

*'  In  order  to  apply  the  acetic  folution  of  tin  upon  cotton  or  linen,  cither  by  the  block  or  the 

r 

^  pencil,  it  is  necefTary  that  it  fhould  contain  gum,  and  be  left  at  red:  for  feveral  days  (upon 
<<  the  piece),  during  which  time  it  quits  its  acid  folvent,  and  depofits  its  oxyde  of  tin,  which 
*^  by  affinity  of  adhefion  will  remain  fixed  on  the  piece  by  attradiing  the  oxygen  of  the  atmo- 
**  fphcrc.  Before  the  piece  is  expofed  to  the  dying  adion  of  any  fubflance  whatever  with 
«  heat,  it  muft  be  boiled  a  few  minutes  in  bran  and  water,  or  with  cow-dung,  after  which  it 
«  muft  be  walhed  in  running  water.  The  colours  to  be  produced  will  be  different,  according 
^<  to  the  dying  drugs  made  ufe  of.  Madder,  vegetable  kermes,  cochineal,  and  fermambouc,  will 
**  afford  reds  of  various  degrees  of  beauty ;  the  wood  St.  Martin  affords  a  brown ;  logwood 
^  various  fhades  of  violet ;  yellow  wood,  quercitron,  yellow  berries  (graines  d*Avignon), 
**  &c.  &c.  afford  yellows.  By  mixing  all  thefe  ingredients  in  different  proportions,  by  weak- 
**  ening  the  acetic  folution  of  tin  more  or  lefs  with  the  gummed  water,  or  by  adding  the  acetic 
^  folution  of  iron,  an  infinity  of  (hades  may  be  produced.  It  is  efTential  to  gum  this  mordant 
-  ((  before  it  is  applied  on  the  linen  or  cotton.  If  this  circumftance  be  forgotten,  the  colours 
'  <<  will  be  lefs  bright;  the  fame  precaution  muft  be  attended  to  when  the  acetic  folution  of  alu- 
<^  mine  is  added.  But,  on  the  contrary,  filks  and  woollens  impregnated  with  ah  ungummed 
^  folution,  then  dried  for  feveral  days,  and  dyed  with  the  beforementioned  ingredients,  exhi- 
**  bit  very  bright  cololirs.  Wool  more  particularly,  dyed  with  cochineal,  then  paffed  through 
^^  boiling  water,  and  afterwards  wafhed,  prefents  the  moft  beautiful  purple. 

^  The  intenfity  of  thefe  colours  will  be  much  increafed  by  ufing  the  muriatic  folution  of  tin* 

**  inftcad 


O/i  the  Art  cf  Dying  iy  coloured  Oxydes  of  Tin.  1^9 

^  inftcad  of  the  acetic.  But  this  folution,  which  becomes  more  and  mo^c  oxygenated  as  it 
"  dries,  and  fucccffi  vely  difengages  a  portion  of  acid,  weakens  the  cotton  or  the  linen,  which  are 
**  impregnated  with  it ;  but  wool  and  fillc  fufFer  lefs*  To  avoid  this  inconvenience,  it  is  ne- 
•*  ccflary  to  defend  the  piece  by  a  folution  of  one  part  of  Marfcilles  foap,  and  fixteen  of 
♦'  water  *.  The  article,  after  drying,  is  to  be  plunged  in  the  muriatic  folution  of  tin  diluted 
"  with  water,  and  when  well  walhed,  i(  may  be  dyed.  The  colours  obtained  by  means  of 
**  fjap  are  m  )re  llvely-J*.'* 

The  author  here  makes  a  very  important  remark  with  regard  to  the  play  of  the  affinities } 
namely,  that  in*order  to  have  the  coloured  oxydes  of  tin  beautiful  and  folid,  it  is  necefTary  that 
there  fhould  remain  a  fmall  quantity  of  combined  acid ;  and  that  neverihelefs  the  fame  colours 
are  obtained  upon  goods  dyed  by  the  intermedium  of  the  folutions  of  tin,  though  thefe  goods 
may  have  been  previoufly  palTcd  through  boiling  water,  which  muft  neceflarily  carry  off  the 
fait  or  acid  which  might  remain,  and  prove  an  impediment  to  the  attraction  of  the  colouring 
parts.  The  author  inclines  to  attribute  this  effecEl  in  linens  and  cottons  to  part  of  the  gum, 
with  which  they  are  impregnated,  remaining  combined  with  the  oxyde,  and  ferving  inftead  of  the 
acid,  while  in  wool  and  filk  the  animal  part  ads  in  a  fimilar  mamier. 

Faffing  afterwards  to  the  operations  made  with  the  alkaline  folutions  of  the  coloured  oxydes, 
which  he  fucceeded  in  obtaining,  deprived  of  all  caufticity,  he  gives  the  following  defcription. 
"  I  commonly  ufe  for  thcfe  fcJutions,  when  the  coloured  oxyde  is  in  the  form  of  powder,  a  fo- 
lution of  potafli  made  with  one  part  of  the  carbonate  of  potafh  in  cryftals,  one  part  of  lime,  and 
eight  parts  of  water.  After  decantation,  and  reducing  the  liquid  to  one-half,  I  pound  and  ftir 
well  the  powder  with  this  liquor.  The  reduSion  of  the  fluid  is  to  be  made  to  one-fourth,  when 
.the  oxyde  is  intended  to  be  diffolved  fimply  as  it  comes  from  the  filter  without  drying.  It  is  thus 
put  into  a  veflel,  and  fhaken  with  the  fluid. 

«  To  avoid  an  excefs  of  potaQi,  the  folution  muft  be  poured  a  little  at  a  time  upon  the 
oxyde,  and  fome  oxyde  muft  be  kept  in  rcferve,  in  cafe  too  much  alkali  (hould  have  been  added* 
This  may  be  eafily  known  by  applying  a  fmall  drop  to  the  tongue. 

**  When  thefe  folutions  do  not  pofiefs  fufficient  confiftence,  they  muft  be  gummed.  By  this 
means  they  become  applicable  by  the  block  or  the  pencil.  They  fix  upon  the  cotton  or  linen 
the  coloured  oxydes,  which,  by  fome  weeks  repofe,  attra£t  the  carbonic  acid  of  the  atmofphere,  is 
with  which  the  alkali  becomes  faturated  by  degrees. 

'*  T  he  precipitation  of  thefe  oxydes  may  likewife  be  made  fpeedily,  and  immediately  after  the 
piece  is  dried,  in  which  method  the  colours  are  alfo  more  vivid.  For  this  purpofe  nothing  more  is 
requifite  but  to  fteep  the  piece  for  fifteen  minutes  in  a  muriatic  folution  of  tin,  diluted  with  twenty 
parts  of  water,  or,  which  is  better,  in  a  (olution  of  fulphate  of  alumine  made  with  eight  parts  of 

^  I  have  given  in  the  Annates  de  Chemie  preparations  of  foap,  which  may  be  ufcd  ioftead  of  that  of  M;|r- 
f«IIIes.     Note  of  the  author. 

t  Journale  dc  Phyfique  Fluvoife.  Annual  Regifter,  vol.  v.  p.  114,  whera  the  entire  ipemoir  it  to  be 
found. 

water. 


j8o  On  the  Art  of  Dying  by  coUured  OxyJes.  tf  Tin. 

water,  the  cxcefs  of  acid  being  abforbed  by  adding  one-eighth  part  of  carbonate  of  lime,  while  the 
liquor  is  hot.  Either  of  thefe  proccffes  with  the  alkaline  folution  of  the  carmine  red  oxyde,  afforded 
by  muriate  of  tin  and  an  infufion  of  cochineal,  produce  nearly  the  fame  (hade  of  carmine,  incrining 
to  crimfon.  The  fhade,  on  the  contrary,  will  l^|Mppy  colour,  if,  inftead  of  the  muriatic  folution, 
the  nitro-muriatic  folution  of  tin  be  added,  diWed  with  the  fame  quantity  of  water;  to  which, 
in  order  to  prevent  fpontaneous  precipitation,  one-fourth  of  the  muriate  of  foda  has  been  added. 
Thefe  colours  are  as  folid  as  the  oxydes  from  which  they  arife.'*     ' 

Citizen  HaufTman  then  gives  a  detail  refpeSing  the  fhades  of  colour,  of  infinite  variety, 
which  may  be  obtained  from  the  various  mixtures  of  the  alkaline  folutions  of  coloured  oxydes: 
very  beautiful  fcarlet  reds  are  afforded  by  a  mixture  of  the  folution  of  the  carmine  oxyde,  with 
that  of  the  oxyde  coloured  by  yellow  wood.  The  folutions  of  indigo  made  by  means  of 
arfenic,  antimony,  or  muriate  of  tin,  may  be  ufed,  but  not  thofe  made  by  the  fulphurets  of  the 
fame  metals,  bccaufe  the  imraerfion  of  the  piece-goods,  which  muft  afterwards  be  made  in  the  ' 
muriatic  folution  of  tin,  or  in  that  of  the  fulphate  of  alumine,  would  precipiute  the  fiilphurets, 
and  render  the  colours  obfcure. 

Thefliades  of  green,  of  violet,  and  of  prune  monfieur,  are  particularly  remarkable;  the  blue 
grounds  can  fcarcely  be  obtained  of  an  even  tinge  but  in  the  vats.  The  folutions  of  indigo, 
gummed,  and  applied  either  alone  or  mixed  with  other  coloured  folutions,  being  ufually  un- 
equal; too  much  excels  of  dkali  in  the  blue  folutions  would  render  the  colours  dull. 

A  fme  Wue  may  likcwife  be  produced  without  the  folution  of  tin,  by  that  of  gummed 
indigo,  dried  on  the  piece,  and  afterwards  fteeped  in  the  folution  of  fulphate  of  alumine:  an 
ingredient  affording  a  yellow  colour  will  complete  the  defired  (hade  of  green. 

Some  of  the  coloured  oxydes  of  tin,  prefent  Angular  k&.% ;  that  which  is  coloured  by  fef- 
nambouc  becomes  clear  and  pale  as  it  dries  on  the  piece,  but  the  colour  becomes  of  a  deep 
red  by  immerfion  In  a  folution  of  fulf^te  of  dumine:  a  iimilar  operation  caufes  the  colour 
from  campeachy  wood  to  become  a  deep  violet,  from  a  bright  reddifh.grey. 

The  alkaline  folution  of  the  oxyde  of  tin,  coloured  by  madder,  requires  more  precautions 
for  its  fuccefs  than  the  forgoing,  and  perceptibly  differs  from  them  in  its  properties-  The 
author  defcribes  die  moft  proper  method  of  obtaining  the  infufion  of  madder,  to  which,  a 
proportionate  quantity  of  carbonate  of  potafli  is  added ;  the  coloured  oxyde  is  obtained  by 
mixing  it  with  the  muriatic  folution  of  tin :  but  in  order  to  obtain  an  intenfe  colour,  it  is 
abfolutely  ncceffary  €o  filter  and  dry  the  oxyde  before  it  is  diffolved  in  the  potafh.  By 
treating  tliis  folution  in  die  fame  manner  as  was  diredled  for  that  of  the  carmine  oxyde,  by 
means  of  the  folution  of  the  fulphate  of  alumine,  and  not  that  of  the  muriate  of  tin,  which  is  not 
applicable  to  die  prefent  experiment,  a  fhade  of  fuperfine  pulverized  madder  is  obtained  ;  by 
boilmg  widi  bran  and  water,  the  fhade,  known  in  manufaftorics  by  the  name  of  the  fecond  red^ 
will  be  obtained,  which  will  become  brighter  by  the  addition  of  gum-water. 

The  alkaline  folution  of  the  oxyde,  coloured  by  madder,  when  it  is  well  made,  is  fufficiendy 
con&ftent  to  be  ufid  widiout  gum. 

It 


Jrt  of  Dying.     Natural  Hi/Iory  of  tU  Elephant.  •  i8i 

It  Is  to  be  regretted,  that  goods  coloured  by  thefe  alkaline  folutions,  retain  the  excefs  of 
colour  and  of  gum  fo  ftrongly,  that  it  is  neceflary  to  rub  them,  in  order  to  clear  it  off;  this 
inconvenience  is  confiderable  in  deep  {hades,  but  lefs  fo  in  thofe  which  are  l^right. 

L^ftly,  the  author  briefly  exhibits  the  properties  of  zinc,  by  way  of  comparing  its  appli- 
cation with  that  of  tin,  as  a  colouring  agent.  If,  like  this  lafl  metal,  zinc  be  fufceptible  of 
forming  lakes  with  vegetable  deco6tions,  or  infufions,  its  properties  differ  much  in  other 
refpefbs  from  thofe  of  tin ;  for,  on  the  one  hand,  the  acetlte  of  zinc  cannot  be  ufed  as  a 
mordant,  becaufe  its  acid  does  not  become  difengaged  by  drying,  and  the  oxyde  requires  an 
alkaline  carbonate  to  fix  it  on  the  piece  \  on  the  other  hand,  the  alkaline  folution  of  the  oxydc 
of  zinc  not  being  capable  of  fuperoxydation,  is  not  proper  to  co-operate  with  the  folution  of 
indigo :  and  the  alkali  not  lofing  its  caufticity,  cannot  be  advantageoufly  ufed  in  the  folution 
of  the  coloured  oxydes'of  zinc. 

Here  concludes  the  tafk  I  have  undertaken  of  giving  an  account  of  the  labours  of 
Citizen  HaufTrpan.  His  paper  abounds  with  fo  many  fa£b,  and  excellent  views,  that  it  is  with 
regret  that  1  have  abridged  his  recital.  I  have  been  careful  to  omit  nothing  of  importance. 
Some  conje£lural  ideas  of  the  author,  refpe£iing  the  produfUon  of  phofphorus,  during  the  folu- 
tion  of  tin  by  the  muriatic  acid,  and  the  compofition  of  metals,  prcfumed,  from  their  analogy 
with  alumine,  are  pafFed  over  in  lilence,  becaufe  the  author  himfelf  does  not  feem  to  attach 
any  confiderable  value  to  thefe  notions,  and  has  offered  them  with  that  modefty  which  ought 
always  to  be  (hewn  with  regard  to  aiTertions,  not  yet  fupported  by  decifive  experiments. 

C.  A.  PRIEUR. 


VIII. 

Obfervations  on  the  Manner Sj  Habits j  and  Natural  Hijlory  of  the  Elephant.     By  JOHif 

CoJiSEy  Efq*. 


s 


INCE  the  remoteft  ages,  the  elephant,  on  account  of  his  fize,  ,his  fagaclty,  and  his  won- 
derful docility,  has  attracted  the  notice,  and  excited  the  admiration  of  philofophers  and  natu« 
ralifts,  both  ancient  and  modern ;  and  few  travellers  into  Aiia,  or  Africa^  have  omitted  giving 
fome  account  of  him. 

A  refidence,  however,  of  more  than  ten  years,  in  Tiperah,  a  province  of  Bengal,  fituated  at 
the  eaftern  extremity  of  the  Britifh  dominions  in  Afia,  where  herds  of  elephants  arc  taken  every 
feafon,  afforded  me  frequent  opportunities  of  obferving  riot  only  the  methods  of  taking  them, 
but  alfo  the  habits  and  manners  of  this  noble  animal. 

From  the  year  1792  till  1797,  the  elephant  hunters  were  entirely  under  my  direftion;  fo 
that  I  had  it  in  my  power  to  inftitute  fuch  experiments  as  I  thought  likely  to  difcover  any  par- 

•  Philof.  Tranf.  1799.  p.  31. 

Vot.IIL— July  1799.  Bb  '  ^         ticulvs 


1^2  N^^^^^J  Hiftori  of  the  Elephant. 

ticulars,  not  formerly  known,  in  the  natural  hiftory  of  the  elephant.  Soon  after  my.  arrival  at 
TiBeraij>  while  informing  myfclf  pf  the  methods  of  taking  wild  elephants,  1  had  occafion  to  ob- 
fcrve,  that  many  errors,  relative  to  the  habits  and  manners  of  that  ufeful  animal,  had  been 
ftated  in  the  writings  of  European  authors,  and  countenanced  by  fome  of  the  moft  approved 

writers. 

The  elephant  has  been  declared  to  poiTefs  the  fentiment  of  modefty  in  a  high  degree ;  and,  by 
fome,  his  fagacity  was  fuppofed  to  excite  feelings  for  the  lofs  of  liberty,  fo  acute  as  to  caufe 
him  to  refufe  to  propagate  his  fpecies  while  in  flavery,  left  he  fliould  entail  on  his  progeny  a  fate 
Croilar  to  his  ownj  whilft  others  have  aflerted,  that  he  loft  the  power  of  procreation  in  the  do- 
meftic  ftate. 

So  circumftanced,  I  was  defirous  of  taking;  advantage  of  my  (ituation,  and  of  making  'fucK 
experiments  and  obiervations,  as  might  tend  to  render  more  perfed:  the  natural  hi(lory  of  this 
ufeful  animal* 

Early  in  the  year  1 7  89,  I  gave  an  account  of  the  methods  ijien  iifed  for  taking  and.  training 
wild  elephants,  to  the  A^fiatic  Society  in  Calcutta,  which  was  publiflied  in  vol.  iii.'  of  their 
Refearcbes :  and  the  following  experiments  and  obfervations,  made  fince  that  period,  on  the 
natural  hiftory  of  the  elephant,  will  not,  I  hope,  prove  unworthy  the  attention  of  the  Royal 
Society. 

The  young  of  the  elephant*  at  its  birth,  is  about  35  inches  high  ;  and,  as  a  knowledge  of  its^ 
progreffive  growth  forms  thcbeil  criterion  by  which  we  can  judge  of  the  age  of  this.am'mal,  I 
ihall  here  i^ote  down  fome  obferv^itions  made  on  this  fiibje£l,  till  the  elephant  has  attained  its 
full  fize  J  for,  after  this  period,  till  figns  of  old  age  appear,  I  do  not  know  any  marks  by  which 
atolerable  guefs  can  be  made  of  the  number  of  its  years,  unlef&Mn;^  couldexamine  the  teeth  ac;- 
curately ;  and,  even  then,  there  would  be  much  uncertainty. 

Very  erroneous  notions  have  been  entertained,  with  refped  to  the  fize  of  elephants,  in  differ- 
ent parts  pf  India;  for  which  reafon,  I  have  collefted'fuch  fefts  as  were  likely  to  afcertain  their 
general  height.  The  following  obfervations,  of  the  gradual  increafe  of  growth,  were  made 
upon  a  young  elephant  of  Mr.  Stephen  Harris,  which  was  accurately  meafured  from  time  to 
time,  and  upon  a  female  elephant  of  my  own,  till  I  left  Tiperah. 

Mr.  Harris's  elephant,  at  its  birth,  Odober  16,  1789,  was  35  inches  high. 

Feet.    Inches. 
In  one  year  he  grew  1 1  inches,  and  was        3  10    high. 

-     46 

5        o 

5         5 

5        10         ,  • 
-         6         IX 
-        -       6         4 
Except  during  his  4th  and  5th  jrears,  the  above  meaTurement  fliows  a  gradual  decreafe  in 

the 


In  the  2d  year 

8 

In  the  3d  year 

6 

In  the  4th  year 

5 

In  the  5th  year 

5 

In  the  6th  year 

3i 

In  the  7th  year 

ai 

Natural  HiJIory  of  thi  Elephant  •  t8j 

the  proportion  of  growth  for  every  year ;  and  there  wis  no  Opportunity  of  tracing  the  growth 
of  this  elephant  further  than  it§.  7th  year. 

Another  elephant,  fix  feet  nine  inches  high,  at  the  time  fhe  came  into  my  pofleflion,  was 
fuppofed  to  be  fourteen  years  old  ;  but,  as  the  accuracy  of  the  hunters  cannot  be  depended  on, 
it  will  be  proper  to  take  Mr.  Harris's  elephant,  whofe  age  is  exafily  known,  as  a  ftandard:  and, 
judging  from  its  annual  increafe,  this  will  lead  us  to  confider  the  elephant,  at  the  time  I  re- 
ceived her,  to  be  only  eleven  years  old ;  giving  a  period  of  four  years,  for  the  addition  of  five 
inches.  I  have  made  a  greater  allowance  of  time,  on  account  of  this  elephant  being  afethale; 
and  Mr.  Harris's  a  male,  which  there  is  much  reafon  to  believe  grows  fafter. 

During  the  next  five  years,  before  (he  was  covered,  (he  grew  only  fix  inches;  but,  what  is  ex- 
tremely curious,  while  pregnant,  (he  grew,  in  twenty-one  months;  five  inches:  and  in  the  fol- 
lowing feventeen  months,  though  again  pregnant,  (he  grew  only  half  an  inch  ;  at  which  time, 
fhe  was  fent  from  Comillah,  as  I  was  then  preparing  to  leave  India. 

At  this  time,  (he  was  about  nineteen  years  old,  and  had,  perhaps,  attained  her  full  growth. 
Her  young  one  was  then  (Nov,  1796)  not  twenty  months  old  5  yet  he  was  four  feet  five  inches 
and  a  half  high,  having  grown  eighteen  inches  fincehis  birth,  which  is  the  greateft  progrefiive 
growdi,  in  the  elephant,  that  I  have  known. 

Thefe  obfervations,  when  applied  to  the  general  growth  of  elephants,  are  to  be  taken  with 
(bme  allowance  ;  fince,  during  die  (late  of  the  firft  pregnancy,  there  is  fo  great  an  irregularity 
iadie  growth  of  female  elephants,  as  alone  occafions  confiderable  difficulty,  even  fuppofing  the 
progreffive  growth  nearly  equal  in  thefpecies.  It  is  probable,  however,  that  this  is  not  by  any 
means  equal :  for,  as  the  elephants  vary  greatly  in  fize,  and  as  males  are  generally  much  taller 
than  fimiales,  we  muft  conclude  they  either  grow  fafter,  or  are  longer  in  attaining  their  full 
growth  *•  fiut  it  may  be  (afely  afferted,  that  elephants,  like  moft  quadrupeds,  propagate  their 
fpecies  biefbre  diey  have  acquired  their  full  growth.  Many  females  have  been  known,  when 
taken  while  pregnant,  to  have  grown  feveral  inches  higher  before  delivery;  and,  as  it  has  been 

ft 

ftated,  that  the  female  elephant  on  which  my  obfervations  were  made,  could  not  exceed  fixteen 
years  when  (he  received  the  male,  it  is  probable  the  wild  female  elephants  are  in  heat  before  that 
period. 

If,  from  the  above  data,  it  may  be  allowed  to  form  a  probable  conje^ure,  elephants  attain 
their  full  fixe  between  eighteen  and  twenty-four  years  of  age.  The  height  of  the  elephant,  I 
bdxeve,  has  been  generally  much  exaggerated.  In  India,  the  height  of  females  is,  in  ge- 
neral, from  feven  to  eight  feet ;  and  that  of  males,  from  eight  to  ten  feet,  meafured  at  the 
Ihoulder. 

I  have  never  heard  but  of  one  elephant,  on  good  authority,  that  much  exceeded  ten  feet : 
this  was  a  male,  belonging  to  Afoph  ul  Dowlah,  the  late  vizier  of  Oude.  His  dimenCons,  as 
obligingly  conununicated  to  me  by  Mr.  Cherry,  then  relident  at  Lucknow,  were  as  follow. 

^  A  mate  elephtnt,  belonging  to  the  Cudws^  Rdjah,  till  he  was  aWe  twenty  years  of  age,  cdntinued  to  in- 
creafe in  height,  and  was  fuppofed  not  to  have  attained  his  full  fuc,  ^hen  I  left  Tiperah :  he  was  then  aoove 
twenty -two  years  old. 

B  b  2  He 


FwCt. 

Inchcfr 

22 

lO} 

10 

6 

12 

2 

IS 

II 

1 84  Natural  Hift&rj  of  the  Elephant, 

He  was  meafured  on  the  iSth  of  June,  1796. 

From  foot  to  foot  over  the  (boulder  - 

From  the  top  of  the  fhoulder,  perpendicular  height 

From  the  top  of  the  head,  when  fet  up,  as  he  ought  to  march  in  ftate 

From  the  front  of  the  face  to  the  infertion  of  the  tail        '      - 

Captain  Sandys,  of  the  Bengal  eftablifhmenc,  obligingly  fhcwed  me  a  lift  of  about  150  cle-» 

phants,  of  which  he  had  the  management  during  the  late  war  with  Tippoo  Sultaun,  ikr  Myforc^ 

and  not  one  of  them  was  ten  feet,  and  only  a  few  males  nine  feet  and  a  half  high.     I  was  very 

particular  in  afcertaining  the  height  of  the  elephants  employed  at  Madras,  and  with  the  army 

under  Marquis  Cornwallis,  where  there  were  both  Ceylon  and  Bengal  elephants ;  and  I  have 

been  affured,  that  thofe  of  Ceylon  were  neither  higher,  nor  fuperior,  in  any  refpe(5t,  to  thofe 

of  Bengal ;  and  fome  officers  affert,  that  they  were  confiderably  inferior,  in  point  of  utility. 

The  Madras  elephants  have  been  faid  to  be  from  feventeen  to  twenty  feet  high;  but, 
to  (hew  how  much  the  natives  of  India  are  inclined  to  the  marvellous,  and  how  liable 
Europeans  themfelves  are  to  miftakes,  I  will  relate  a  circumftance  that'happened  to  myfelf* 

Having  heard,  from  feveral  gentlemen  who  had  been  at  Dacca,  that  the  Nabob  there  had  an 
elephant  about  fourteen  feet  high,  I  was  defirous  to  meafure  him;  efpecially  z%  I  had  feen  him 
often  myfelf,  during  the  year  1785,  and  thenTuppofed  him  to  be  above  twelve  fcct  After 
being  at  Tiperah,  and  having  feen  many  elephants  caught,  in  the  years  1786,  1787,  and 
1788,  and  finding  all  of  them  much  inferior  in  height  to  what  I  fuppofed  the  Nabob's  elephant^ 
I  went  to  Dacca,  in  1789,  determined  to  fee  this  huge  animal  meafured.  At  firft,  I  ient  for 
the  driver  %  to  aflc  fome  queftions  concerning  this  elephant;  he,  without  hefitation,  aflured 
me  he  was  from  ten  to  twelve  cubits,  that  is,  from  fifteen  to  eighteen  feet  high ;  but  added, 
he  could  not,  without  the  Nabob's  permiffion,  bring  me  the  elephant  to  be  examined.  Per- 
miffion  was  accordingly  afked,  and  granted :  I  had  him  meafured  exadly,  and  was  rather  fur- 
prifed  to  find  he  did  not  exceed  ten  feet  in  height 

The  honourable  company's  ftandard,  for  ferviceable  elephants,  is  feven  feet  and  upwards, 
meafured  at  the  (boulder,  in  the  fame  manner  as  horfes  are.  At  the  middle  of  the  back, 
they  are  confiderably  higher ;  the  curve  or  arch  of  which,  particularly  in  young  elephants^ 
makes  a  difference  of  feveral  inches. 

After  an  elephant  has  attained  his  full  growth,  it  is  a  fure  fign  of  old  age  when  this  curve 
becomes  lefs;  and  ftill  more  fo,  when  the  back  is  flat,  or  a  little  deprefled..  A  partial  de- 
preffion  of  the  fpine  is,  however,  no  uncommon  occurrence,  even  in  very  young  elephants ; 
and  I  am  convinced  it  happens  from  external  injury.  I  have  been  furprifed  to  fee  the  violence 
ufed  (in  herds  of  wild  elephants  juft  taken)  by  the  large  elephants,  both  male  and  female, 
putting  the  projefting  part  of  the  upper  jaw,  from  which  the  tufls^s  grow  out,  on  the  fpine  of 
the  young  ones,  and  preffing  them  to  the  ground,  while  they  roared  from  pain. 

It  has  been  ftated^  that  the  fagacity  of  the  elephant  is  fo  great,  and  his  memory  fo  retentive^ 

*  Or  mabofCi  &$  he  is  generally  called. 

that 


Natural  Hijlory  of  the  EUphani.  1 85 

that  when  once  he  has  received  an  injury,  or  been  in  bondage,  and  afterwards  efcapes,  it  is 
not  poffible,  by  any  art,  again  to  entrap  him.  Great  as  my  partiality  is  for  this  noble  animal, 
whofe  modes  of  life,  and  general  (agacity  I  have  had  fo  many  opportunities  of  obfcrving,  yet  a 
regard  to  truth  compels  me  to  mention  fome  facls,  which  contradi(^  that  opinion.  The 
following  hiftory  of  an  elephant  taken  by  Mr.  Leeke*,  of  Longford  Hall,  Shroplhire,  con- 
tains many  interefting  particulars  on  this  fubje£l.  The  elephant  was  a  female,  and  was  taken 
at  firft,  with  a  herd  of  many  others,  in  the  year  1765,  by  Rajah  Kifhun  Maunickt>  who, 
about  fix  months  after,  gave  her  to  Abdoor  Rezah,  a  man  of  fome  rank  and  confequence  in  the 
diftrid.  In  1767,  the  Rajah  fent  a  force  againft  this  Abdoor  Rezah,  for  fome  refraftory 
conduiSl,  who,  in  his  retreat  to  the  hills,  turned  her  loofe  into  the  woods,  after  having  ufed 
her  above  two  years,  as  a  riding  elephant  In  January,  1770,  (he  was  retaken  by  the  Rajah  ; 
but,  in  April,  1771,  ftie  broke  loofe  from  her  pickets,  in  a  ftormy  night,  and  efcaped  to  the 
hills.  On  the  25th  of  December,  1782,  (he  was  driven  by  Mr.  Leeke's  elephant  hunters  into 
a  keddah  X\  and,  the  day  following,  when  Mr.  Leeke  went  to  fee  the  herd  that  had  been  fe« 
cured,  this  elephant  was  pointed  out  to  him  by  the  hunters,  and  particularly  by  a  driver  who 
had  charge  of  her  for  fome  time,  and  well  recoUefted  her.  They  frequently  called  to  her 
by  name ;  to  which  fhe  feemed  to  pay  fome  attention,  by  immediately  looking  towards,  them, 
when  her  name,  Juggut-Peaurcey  was  repeated  j  nor  did  (he  appear  like  the  wild  elephants, 
which  were  conftantly  running  about  the  keddah  in  a  rage,  but  feemed  perfedly  reconciled  to 
her  fituation. 

*  He  was  then  the  refident  of  Tiperah,  and  took  fome  pains  to  afcertain  the  fa£ls  here  mentioned. 

-|-  The  Rajah  is  the  principal  Zemindar  in  the  province  of  Tiperah,  paying  the  ufual  revenue  for  his  lands 
in  the  low  country ;  but,  in  the  hills  he  is  an  independent  fovereign,  has  the  power  of  life  and  death  over 
his  fubjefts,  a  mint,  and  other  iniignia  of  fovereignty. 

X  The  inclofure  in  which  elephants  are  fecured.  Fide  AHatic  Refearches,  Vol.  III.  Art.  ^'  Method  of 
catching  Elephants." 

(T$  be  concluded  hereafter.) 


PHILOSOPHICAL  NEWS  AND  ACCOUNTS  OF  BOOKS. 

m 

Experiments  on  the  Vibrations  of  Plates  of  Glafs.     By  Profeffor  Chladniy  of  Berlin. 


I 


N  the  year  1787,  M.  Chladni  publifhed,  at  Leipzic,  a  work  in  German,  entitled,  DtfcO'^ 
veries  r^fpeSiing  the  Theory  of  Sound '^  in  which  he  announces,  that  if  glafs,  fprinkled  with  fine 
powder,  be  made  to  found,  this  powder  will  be  fo  diftributed  by  the  effeft  of  the  vibrations, 
as  to  form  very  remarkable  figures,  which  are  conftantly  produced  under  fimilar  circum- 
ftances. 

Thefe 


l86  Refonant  Figttres  on  Gla/s.'-^Phih/ophical  Tranf anions. 

Thefe  experiments  have  been  lately  repeated  at  Paris.  In'order  to  make  them  with  fuccefs, 
it  is  neceffary  to  take  a  fquare  piece  of  glafs,  three  or  four  inches  wide,  not  too  thick,  and 
without  either  bubbles  or  knots.  This  plate  is  to  be  held  firm  between  two  very  pointed 
pieces  of  cork,  and  then  powdered,  with  very  fine  fawduft  or  fend  ;  and  when  the  bow  of  a 
violin,  well  roziried,  is  drawn  againfl  the  edge  of  the  glafs,  blunted  or  rounded  by  grinding, 
a  found  will  be  produced,  and,  at  the  fame  time,  the  powder  will  be  feen  to  difpofe  itfelf  in 
lines  which  afford  different  figures,  according  to  the  manner  or  place  at  which  the  glafs  is 
held,  the  bow  is  drawn,  and  the  found  produced. 

If,  for  example,  the  fquare  be  pinched  by  its  centre,  and  the  bow  drawn  along  the  middle 
of  one  of  its  fides,  die  powder  will  difpofe  itfelf  in  tWQ  lines,  nearly  diagonal  to  the  fquare.' 
If  the  bow  be  drawn  at  the  diftance  of  one-fourth  of  the  fide  firom  the  angle,  the  two  line^ 
will  become  the  fides  of  an  ofiagon,  and  the  found  will  be  the  ofbive  of  the  preceding  tone. 

By  varying  the  pofition  of  the  point  at  which  the  gtafs  is  held,  the  figures  alfo  become 
changed. 

If  the  plate  of  glafs  be  circular,  and  the  bow  be  a  little  inclined,  the  fijt  radii  of  an  hexagon 
will  be  formed. 

In  this  manner,  Mr.  Chladni  obtained  r66  different  figures,  which  he  calls  refonant  figures. 
Without  precifely  explaining  the  caufe  v^hich  produces  thefe  figures,  their  analogy  with  the 
ftationary  and  vibrating  parts  of  a  mufical  ftrJng  evidently  (heWs  diat  the  vibrating  furface  di- 
vides itfelf  into  a  number  of  portions  which  move  feparately,  but,  no  doubt,  in  an'ifochronous 
or  commenfurate  manner,  when  the  tones  are  clear  ancf  mufical.  The  lines  in  which  the 
powder  is  colle£bd,  are  a  kind  of  gutters  formed  by  the  points  which  remain  at  reft,  while  the 
other  parts  become  alternately  convex  and  concave. 

Thefe  experiments,  which  fucceed  equally  with  plates  of  metal,  and  even  of  wood,  being 
carefully  maide  and  clafled  fyffeihatitaily,  prdmife  to  throw  much  light  on  the  manner  in  which 
furfaces  vibrate,  and  may,  perhaps,  tend  to  the  improvement  of  the  theory  of  Wind  inftrumentjs^ 
and  other  mufical  apparatus,  w&ich  is  ^I  ^ery  imperfeft,  notwithftanding  the  labours  of 
Euler,  in  attempting  to  reduce  them  to  computation. 

Decade  Philof.  Na  17.  Art.  VIL- 


* 
Philofopbical  Tranfafitons  of  the  Royal  Society  of  London^  for  the  Tear  1799.     Part  the  Firjl. 

Quarto^  156  Pages^  with  three  Plates  ;  London^  fold  by  Elmfly. 

This  part  contains,  i.  The  Croonian  le£lure.  Experiments  and  obfervations  upon  the  ftruc* 
ture  of  nerves.  By  Everard  Home,cfq;  F.R.S.  2*  The  Bakerian  lefture.  Obfervations  upon 
an  univerfal  horisfontal  refradion  of  the  air;  with  remarks  on  the  variations  to  which  the 
lower  parts  of  the  atmofphere  are  fometimes  fubjed.  By  the  rev.  S.  Vince,  A.M.  F.R.S.  and 
plumian  profeflbr  of  aftronomy  and  experimental  philofophy  in  the  univerfity  of  Cambridge* 
3.  Abftra6t  of  a  regifter  of  the  barometer,  thermometer,  and  rain,  at  Lyndon,  in  Rutland,  1797. 

With 


Philofophical  Traufa£iloH$.'^Trea$ifi  bn  Time-pieees.  187 

Wiih  fome  remarks  on  the  recovery  of  injured  trees.  By  Thomas  Barker,  Efq.  4.  Some  ad- 
ditions to  a  paper  read  In  1 790,  on  the  fubje^^i  of  a  child  with  a  (iouble  head.  By  Evcrard  Home, 
£fq;  F.R.S.  5.  Obfcrvations  on  the  manners,  habits,  and  natural  hiftory  of  the  elephant.  By 
John  Corfe,  Efq.  6.  On  the  decompofition  of  the  acid  of  borax,  or  fedadve  fait.  By  Law- 
rence de  Crell,  M.D.  F.R.S.  Lond.  and  Edinb*  and  M*RL  A.  traoflated  from  (he  German. 
7.  A  method  of  finding  the  latitude  of  a  place,  by  means  of  two  altitudes  of  the  fun,  and  the 
time  elapfed  betwixt  the  obfervations*  By  the  rev.  W.  Lax,  A.M.  Lowndes's  profcffor  of 
Aftronomy  in  the  univerfity  of  Cambridge.  8^  A  fourth  catalogue  of  the  comparative  bright- 
nefc  of  the  ftars.  ^y  William  Herfchel,  LL.D.  F.R.S.  9.  On  a  fubmarine  foreft  on  theeaft 
coafliQf  England.  By  Jpfeph,  Correa  de  Seraa,  LL.D.  F.R.S.  and  AS.  Appendix.  Meteo- 
rological journal,  kept  at  the  apartments  of  the  Royal  Society,  by  order  of  the  prefident  and 
counciL 


Traiti  dis  Montns  a.  Longhujfs^  &r.  or  a  treatife  on  time-pieces,  containing  the  defcrip- 
tion,  conftru£Hon,  and  all  die  details  relative  to  the  workmanfhip  of  thefe  machines ;  their  di- 
menfions,  the  method  of  trying  them,  &c.;.  together  with,  i.  An  inftruftive  memoir  on  the 
fabrication  of  clocks  and  timerpiec;es ;  2^  Defcription  of  two  aftronomical  clocks ;  3.  Trial 
of  a  fimple  method  of  preferving  the  relation  of  weights  and  meafures  j  and  of  eftablifhing  an 
univerfal  and  perpetual  meafure.  One  volume  in  qu^to,  with  feven  engraved  plates;  by 
Ferd.  Bertkoud,  of  the  national  inftjitute  of  France,  and  mechanic  to  the  marine.  Sold  at 
Paris  by  the  author  aux  Galleries  du  Louvre,  1792* 

This  work  «,  though  it  has  been  printed  ieven  years,  has  not  been  puUi£h;:d  till  lately ;  and. 
we  haften.to  announce  it  to  the  pi^bljc.  It  .is  an  ipiportant  fupplement  to  the  Eflai  fur  I'Hor- 
logerie,  2  vols,  in  quarto,  publxfhed  in  1763  and  178.6ft  and  to  the  Traite  des  Horloges  marines, 
1773,  of  the  (ame  author. 

The  firft  article  confifts  of  the  dcfcription  of  a.marine  time-piece,  portable  and  vertical,  de- 
noted by  the  number  46,  which  has  been  ufedat  (bt  It  is  flung  in  jimbals  j  and  when  ufed 
on  fhore  it  is  carried  in  the  pocket.  On  this  occafion  we  find  a.  defcription  of  a  new  free 
efcaperoent.  *  • 

The  fecond  chapter  prefents  a  defcription  of  a. portable  vertical  watch,  without  a  fufpenfion, 
diftinguiibed  by  the  number  47.     It  has  the  common  form  of  a  pocket  watch. 

In  the  third  and  fourth  chapters  defcriptions  are  given  of  two  fmall  horizontal  watches  in- 
tended to  ferve  as  regulators,  remaining  at  reft  in  the  veflel,  carried  by  their  fufpeniions :  that 
which  is  denoted  by  number  45  makes  four  vibrations  per  fecond.  In  the  other  time-piece, 
no.  48,  the  balance  makes  two  vibrations  per  fecond. 

Chapter  V.  contains  the  moft  efTential  details  for  the  execution  of  watches  and  fmall  time- 
pieces for  the  longitude. 

*  This  acccont  is  given  by  Lalande  in  the  MagaOn  Encyclip^dique,  Vil.  113. 

Chapter 


1 88  Treatife  9n  Tmi-pUces* 

Chapter  VI.  treats  of  the  compenfation  for  temperature  produced  by  the  balance  itfelf. 

In  the  fevenrh  chapter,  cit.  Berthoud  gives  the  conftruSion  and  means  of  executing  a  port- 
able watch,  the  compenfation  of  which  is  produced  by  the  balance  and  the  pendulum  fpring. 
And,  ladly,  he  explains  the  confirudion  of  a  vertical  watch,  without  a  fufee,  and  carried   by 
fufpenfion.     A  method  is  given  to  remedy  the  want  of  ifochronifm  in  the  pendulum  fpring  by 
means  of  the  balance  itfelf 

I'he  fccond  volume  of  this  work  is  entitled,  Suite  duTraitedes  Montres  a  Longitudes,  &c.  or 
Supplement  to  the  Treatife  on  Time-pieces,  containing  the  conftrudion  of  portable  vertical 
watches  (montres),  and  of  horizontal  time -pieces  (horloges),  for  the  longeft  voyages:  the  de^ 
fcription  and  trials  of  fmall  horizontal  *  watches,  very  (imple  and  portable  ;  with  two  engraved^ 
plates.    Paris,  in  the  5th  republican  year. 

This  volumcf  which  has  been  printed  a  year,  has  not  yet  been  announced  or  publifhed.  It 
is  divided  into  two  parts.  Citizen  Berthoud,  in  the  firft  place,  treats  of  the  queftion  of  the 
bed  pofition  for  portable  watches,  and  fmall  time-*pieces.  In  the  next  place,  he  treats  of  the 
mod  convenient  number  of  vibrations  of  the  balance,  to  diminifh  the  fridions,  and  render  the 
watch  mod  convenient  for  the  obferver.  He  defcribes  the  conftruAion  of  the  balance,  which 
bears  its  own  compenfation ;  the  mod  Ample  and  fure  condru£iion  of  the  free  efcapcment,  and 
the  fpiral  fprings  of  watches  to  render  the  vibrations  of  the  balance  ifchronal ;  the  defcription  of 

■    *  ■ 

the  eladic  balance,  ferving  for  the  meafure  and  proof  of  the  fpiral  fprings  \  and,  ladly,  he  ex- 
plains the  method  of  trying  time-pieces. 

In  the  fecond  part,  we  find  the  condru£lion  of  the  vertical  watch,  no.  56. — the  portable  vertical 
watches,  no.  60  and  62  ;— of  the  fmall  horizontal  time-piece,  no.  63.  condru6led  to  give  the 
longitude  in  the  longeft  voyages ; — of  the  fmall  horizontal  time-piece,  no.  66.  without  (rouleau}. 
And  in  the  conclufion  the  author  treats  of  vertical  watches,  and  fmall  horizontal  time-pieces. 
The  author  gives  the  preference  to  the  latter. 

This  work  is  terminated  by  a  fupplement,  containing  the  refult  of  the  trials  made  with  the 
horizontal  watch,  no.  65.  in  which  the  pivots  of  the  balance  turn  fimply  in  holes  made  in 
copper  (cuivre) ;  and,  ladly,  we  find  the  conftru£tion  of  a  very  fimple  portable  watch,  and  of 
a  fmall  horizontal  time-piece  improved  from  no.  65.  • 

In  the  tfl'ay  on  weights  and  meafures,  the  author  gives  the  dimenfions  of  a  cylindrical  pendu- 
lum, vibrating  oh  knife  edges,  repreferifling  the  French  foot,  and  the  refults  of  trials  made  in 
1 791,  to  determine  the  ofcillations,  which  proved  to  be  7710  per  hour.  Though  the  pendulum, 
has  been  abandoned,  in  order  to  fubftitute  the  ten-millionth  part  of  the  quadrant  of  the  meridian, 
yet  the  labours  of  citizen  Berthoud  to  preferve  the  dimenfions  of  any  determinate  pendulum, 
cannot  be  viewed  without  intereft. 

Upon  the  whole,  this  new  work  is  calculated  to  add  to  the  reputation  of  its  illudrious  author^ 
and  exhibits,  without  mydcry,  thofe  praSices  which  have  procured  him  repeated  fuccefs  in  his 
marine  time -pieces,  of  which  the  production  is  of  fo  much  importance  to  navigation. 

*  I  fuppofe  the  words  horizonml  and  vertical  in  the  who'e  of  this  account,  to  rcla:e  merely  to  t!  e  pofition  in 
which  the  time-piece  is  to  be  habitually  kept,  and  noi  tn  the  nature  of  their  efcapementt.  The  word  horizontal 
has  nor,  J  believe,  been  applied  to  any  tfcapcment  by  iiic  French.    N# 


AOu  JtanalT^jnJt,Vn,Aiiiu)pjM. 


V-t'"7 


u///^ftti/> 


/  /t<>)i  ■/ ■///*■//  ^/t/yi'trt-Z/o/f 


:mkL 


^•^mmm^r^m^^ 


nJi;iJw  UiiHARY 


ttLVftM   r«ttIH*ATtOH8 


i 


1Q  r:v^  Y»K 


•wi 


asBBssssssssse 


AS59K 


ttSSS 


mmmi 


JOURNAL 


or 


NATURAL   PHILOSOPHY,    CHEMISTRY, 


ANI> 


THE   ARTS. 


J'UGUS^  1799. 


ARTICLE    L 

Supphtttnt  tt  tbt  Btt^tr  m  tbt  PJtibfiphieal  l^ts  rf  a  Ctmmm  Watch,    Bj^  th*  Rtv.  Wm 

PEARSOKf  of  Luictbu 


TO  MR.  NICHOLSON^ 


A 


Sllt^ 


S  the  paper  *«•  On  the  Philolophical  Ufes  of  a  common  Pocket  Watch,**  which  I  fent 
youy  was  deemed  fufficiently  important  to  be  inferted  in  your  Journal,  I  am  induced  to  tranf- 
mit  to  you  fome  additional  numbers,  fiiitable  for  a  watch  that  may  indicate  hours,  minutes,, 
&conds,  and  quarters  of  a  fecond,  Without  any  extra- wheel  work  ;  in  order  that,  out  of  the- 
different  varieties,  the  watch-maker  may  &lc<5l  fuch  numbers  as  are  already  marked  upon  the 
plate  o£  liis  engine ;   for  I  underftand  that  64,   one  of  the  numbers  propofed  for  a*  ms^r 
watch,  though  as  eafily  divided  as  any  other  nbmber,  is  not  ufualljr  put  upon  the  common; 
plates  of  watch-makers^ — That  the  different  prafHcable  varieties  floay^  be  exprefliMl  in  as  con-^ 
ciie  a  manner  as  is  confiftent  with  perfpicuity,  1  will  divide  the  whole  train  of  a  watch  intO' 
tliree  portions:  that  part  which  comprehends  the  fufee,  the  great  wbed^  and  its  pinion,,  may 
be  denominated  the  firft  portion;  the  fecond  portion  may  be  the  centre  vi^eel,  with  the* 
pinion  which  it  a<^ates,  and  the  third  wheel  with  the  pinion  abated  by  it,  which  is  placed: 
VoIm  IIIt>«i>AuGUST  J799»  C  c  oni 


^go  On  the  Trains  of  Clods  and  PFatches. 

on  the  axle  of  the  contrate  wheel ;  and  the  third  portion  will  then  be  the  contratc  wheel, 
with  the  pinion  aftuated  by  it,  the  crown  wheel,  and  the  palats :  the  firft  portion  determines 
the  time  that  a  watch  ihall  go  at  one  winding  up,  as  has  been  obferved  before ;  the  fecond 
portion  determines  the  mutual  velocities  of  the  minute  and  fecond  hands;  and  the  third  por- 
tion regulates  the  number  of  beats  per  fecond :  hence  any  one  of  thefe  portions  may  be  con- 
ftrufted  varioufly,  without  affcfting  the  calculations  of  the  two  others. 

If  a  watch  be  required  to  have  6  fpirals  on  th«  fufee,  and  to  go  juft  30  hours,  we  fhall 

have  for  the  firft  portion  6x— ,  6x— ,  6x— >  and  6  X  —  :  for  the  fecond  portion  we 

^  9      10     ir       12  ^ 

,      48   4C   4C    48  60   42   42   60  60   48    48    60   60 
maytake  ~  X  ^.or-^  X  -^,  -^  X  ^.or-  X  -^.  3-  X  g,  or±..x  -g-,  -^  X 

C4   C4   60  60   60   60   60  60   40   49   60  60    c6   56   60 

9      9      00      10     10      07       77       77       00       7 

63       60       60       6^        J   1  /ii  II-        60       64       64       60     ,.,      ..    ^ 

^  X  — ,  or  —  X  "^  >  and,  laftly,  as  already  given,  vr    X  77 ,  or  jj^-  x    r-:   likewife,  for 

7997  DOOO 

64X15X2        56XICK2  J    48x15X2  -        ,., 

the  third  portion,  we  may  put    ^    g y    -" >  ^"^. g >  ^7  ^^^  o^  which 

formulae,  divided  by  60,  the  feconds  in  a  niinutc;,  wUl  give  4  Tor  the  number  of  beats  per 

fecond. 

Here  then  we  have  got  four  varieties  of  the  firft  portion,  mne  of  the  fecond,  without  in- 
verting the  order,  and  three  of  the  third,  which,  by  the  rule  for  finding*  compofitions,  will 
produce  4x9x3=108  different  forms  of  contraction,  to  anfwer  the  (ame  purpofe,  without 
making  any  alteration  in  the  number  of  .fpirals  on  the  fufee,  or  in  the  dial-work ;  and  where 
no  number  out  of  all  the  wheels  exceeds  64,  or  is  lefs  than  42. 

The  allowance  to  be  made  in  correcting  the  feconds  gained  by  the  beats  of  any  watch 
muft  be  ,^^0  of  the  whole,  for  every  minute  in  the  daily  error  in  the  rate  of  going,  plus  or 
minusj  accordingly  as  the  rate  is  too  flow  or  two  feft:  therefore,  in  the  fecond  note  (N), 
page  50,  where,  for  an  error  of  five  minute$,  it  is  (aid  that  the  allowance  will  be  '^  lefs  than 
sio"  of  the  whole,  it  ought  to  have  been  «  upwards  of  jio  :'*  for  tw=  »'J"8  >s  a  greater 
portion  of  unity  than  j^o*  though  inadvertency  it  might  be  taken  as  conftituting  a  fmaller. 

It  may  probably  appear  too  ibrmal  to  notice  here  two  typographical  errors  in  the  defcrip- 
tion  of  the  numbers  propofed  for  a  new  watch  in  my  laft  paper,  where  «  2  pivots"  ought  to 
have  been  "  2  palats,"  (or  **  pallets,"  or  "  palettes,"  for  different  authors  fpell  this  word 
differently)  ;  and  6  fpirals  on  the  "  barrel,"  6  fpirals  on  the  <«  fufee;"  but  it  is  abfolutely.ne- 
ceffary  to  advert  to  another  paffage  therein,  which,  partly  from  my  own  inaccuracy,  which 
you  have  already  noticed,  and  partly  from  the  printer's  omiffion  of  the  figns  +  and  — j,  as  it 
now  ftands,  is  completely  unintelligible.  At  the  afterifk  in  page  53,  let  the  fentence  be  un-. 
derftood  to  be  thus  :  as  23  h.  56  m.  4,098  f«  (the  length  of  a  lidereal  rotation  of  the  earth )^ 

^  Vide  HBtton*s  Courfe  of  Mathematics,  voL.i.  p.  r34« 

plus 


On  tbi  Trains  rf  Qoehs  and  Watcheu  ipi 

plus  or  minus  the  daily  error  in  the  rate  of  going  :  arc  to  360°  :  :  fo  is  die  number  of  ob- 
ferved  feconds  of  time  :  to  the  quantity  of  the  horizontal  angle  required. 

Thefe  are  all  the  additional  obfervations  which  feem  neceflary  to  make,  refpefting  the  num- 
bers of  a  new  watch  calculated  for  philofophical  ufes,  and  the  method  of  applying  it ;  but 
there  is  another  inftrument  frequently  to  be  met  with,  which  is  capable  of  various  conftruc- 
tions,  that  will  meafure  fmallcr  portions  of  time,  than  it  is  ufually  made  to  meafure ;  and 
which  is  fufficiently  portable  for  being  carried  fmall  didances:  I  mean  the  fpring  clock,  the 
vibrations  of  which  are  regulated  by  a  (hort  pendulum.  Out  of  the  many  inftruments  of 
this  kind  which  I  have  noticed,  I  do  not  remember  any  one  which  measures,  or,  at  leaft, 
which,  indicates  feconds:  I  (hall,  therefore,,  fubjoin  fuch  numbers  as  are  proper  for  a  fpring 

docky  that  (hall  indicate  feconds,  and  alfo  make  a.given  number  of  vibrations  in  a  fecond. 

If  39,2  inches  be  taken  as  the  true  length- of  a  pendulum,  to  fwing  feconds  in  our  climate, 
which  varies  not  one-tenth  of  an  inch  from  the  rcfult  of  Mr.  Whitehurft's  and  George 
Graham*s  experiments  on  the  lengths  of  pendulums,  the  error  in  the  length  of  fmall  pendu- 
lums, calculated  therefrom,  will  fall  within  the  threads  of  the  adju(}ing  fcrew  at  the  inferior 
end  of  the  rod;  on  which  account  the  lengths,  fo  deduced}  may  be  put  down  as  the  true 
kngth9  without  impropriety :  thus, 

4    vibrations  in  a  fecond  will  require  a  pendulum  •  2,4.5  inches  long. 

3    do.  -  -  -  -  -  4,35 

2f  do.  •  -  -  -  -  6,27 

2tdo»  -  -  •  •  -  7,74 

a    do.  -  -  -  -  -  9,8    . 

The  two  firft  of  thefe  pendulums  appear  to  be  too  (hort  to  perform  with  fteadinefs,  and 
confequently  will  be  confidered  as  unworthy  of  further  notice.  The  firft  portion  of  a  train, 
fuitable  for  any  of  the  three  laft  pendulums,  for  a  fpring  clock  to  go  upwards  of  a  week,  may 

84  ,     -  -  84  06 

be  -^xi?  ^"rns  on  the  fufee,  or   -Ixi5  turns,  or  ^Xi2  turns,    or  indeed   any  other 

iimilar  numbers  producing  a  like  refult :  for  the  (econd  portion,  any  one  of  the  formula  given 
for  a  watch  in  the  former  part  of  this  article,  will  be  proper ;  but  for  the  laft  portion,  each 
different  pendulum  will  require  different  numbers  :  a  pendulum  to  make  2^  vibrations  on  a 
fecond,  may  have  the  contrate  wheel  24,  its  pinion  8,  and  the  crown  wheel  25 1  or,  other- 
wife^  the  contrate  wheel  40,  with  a  pinion  of  8,  and  the  crown  wheel  15  :  where  the  vibra- 
tions are  2}  in  a  fecond,  the  contrate  wheel  may  be  36,  with  a  pinion  of  8,  and  the  crown 
wheel,  as  before,  15  :  and  for  tX2£k\y  two  vibrations  in  a  fecond,  the  contrate  wheel  will  be 
required  to  be  32,  with  a  pinion  of  8,  and  the  crown  wheel  15,  as  in  the  two. laft  inftances. 
In  all  thefe  calculations,  a  band,  placed  on  the  axle  of  the  contrate  wheel,  will  indicate  fe- 
conds without  apparent  recoil ;  and  the  trains,  compofed  of  any  of  the  various  portions  laid 
down,  will  be  equally  accurate,  and  admit  of  many  varieties. 

If  a  fpring  clock  is  to  be  ufed  for  meafuring  fmall  portions  of  time,  by  the  vibrations  of  Its 
pendulum,  which  falls  not  under  the  defcriptibn  of  any  of  thoic  conftnidions,  the  vibrations 

Cca  find. 


tgz  On  thi  Trains  of  Clocks  and  TVatclis% 

and  fraflional  parts  of  a  Vibration  are  calculable  by  the  general  rule  for  watches  alreadf 
given. 

\  ani)  fir,  with  much  efteem,  your's,  &c» 
Lincoln^  May  g,  1799.  W.  Pearson* 

P.  S.  Since  the  preceding  part  of  this  article  was  written,  I  have  met  with  a  train  propofed 
for  a  new  watch  to  indicate  feconds,  and  quarters  of  a  fecond,  by  the  beat,  under  the  word 
^<  clock/'  in  vol.  v.  part  i.  p.  76,  of  the  Encjrclopedia  Britannica,  which,  by  the  mode  of 
expre/fion  adopted  before,  will  ftand  thus : 

48  great  wheel 
12     60   fecond  or  centre  do* 
10       60  third  do. 
^\  turns  on  the  fufee.  6  48  contrate  do. 

To  go  30  hours.  6     15  crown  do* 

2  palettes. 

The  reader  will  perceive  that  thefe  numbers  conftitute  one  of  the  108  varieties  given 
above,  except  that  the  great  wheel  is  given  fmaller  here,  by  reafon  of  the  fufee  having  more 
fpirals.  Under  the  fame  article,  I  alfo  find  that,  as  I  fuppofed,  fpring  clocks  are  not  con- 
'  firuAed  to  (hew  feconds,  though  it  has  been  fliewn  that  they  are  capable  of  many  difEerent 
conftruftions,  which  are  equally  calculated  to  anfwer  this  purpofe,  as  well  as  to  make,  at  the 
fame  time,  a  given  number  of  vibrations  in  a  fecond. 

Likewife,  I  have  juft  had  an  opportunity  of  examining  a  fmall  larum,  or  alarum  dockt 
going  by  a  fufpended  weight,  and  regulated  by  a  fhort  pendulum  only  4^  inches  long,  vrfiich^ 
confequcntly,  makes  upwards  of  three  vibrations  in  a  fecond,  and  which,  I  underftand,  mea« 
fures  time  pretty  accurately.    I  mean  as  accurately  as  thefe  docks  are  intended  to  do ;  for 
great  accuracy  cannot  be  expeded  from  a  clock  with  a  very  (hort  pendulum,  particularly  if  it 
be  a  fpring  clock  that  goes  a.  week  ;  on  account  of  the  difficulty  of  forming  the  fufee  to  cor- 
refpond  exaftly  to  the  aftion  of  a  powerful  fpring  for  many  fucceffive  days,  as  well  as  on 
.account  of  the  imperfcdtions  of  the  pendulum:  but  whatever  be  the  error  in  any  day,  the 
error  in  the  time  of  a  beat  of  that  day  will  be  a  proportional  part  thereof ;  and  provided  the 
rate  of  going  be  tolerably  uniform  throughout  each  fucceffive  day,  after  winding  up,  the 
beats  will  *alfo  be  nearly  uniform :  I  fliall,  therefore,  give  the  numbers  proper  for  the  third 
portion  of  a  train  fuitable  for  a  pendulum,  to  vibrate  three  times  in  a  feccmd,  which  I  had 
purpofely  omitted.     If  any  of  the  ift  or  2d  portions,  already  Ipecifiedt  be  adopted,  the  con- 
trate wheel  will  be  48,  with  a  pinion  of  8,  and  the  crown  wheel  15.     I  have  preferred  .a 
pinion  of  fi,  from  a  perfuafion  diat  this  number  will  render  the  works  of  a  veatoh  or  dock 
more  perfeft,  than  either  7  or  6  would  do  \  and  is  the  number  we  6nd  in  the  befl  finifhed 
inflruments.     If  any  perfon  fhould  wi(h  to  try  the  action  of  a  pendulum  tp  fwing  file  quar- 
ters of  a  fecond  exadly,  any  of  the  trains  propofed  for  a  new  watch  will  te  found  applicable 
to  this  purpofe.    The  reafon'why  an  odd  immber  is  always  fixed  upon  as  proper  for  a  crown 
wheel,  will  need  no  explanation* 

May  iitb.  IL  Obfer-^ 


Hatural  Hijiory  of  the  Elephant.  493 

II. 

Obfervatlons  on  the  Manners ^  Habits^  and  Natural  Hiftory  of  the  Elephant.  By  John  Corse^ 

Efq.     (Continued from  p,  185.) 

J/  ROM  the  25th  of  December  to  the  13th  of  January  (a  fpace  of  eighteen  days),  flic 
never  went  near  enough  the  outlet  (or  roomee)  to  be  fecured ;  from  a  recolle£Uon,  perhaps, 
of  what  flie  bad  twice  before  fuiFered  *•  Orders,  howcveri  bad  been  given,  not  to  permit 
her  to  enter  the  outlet,  had  (he  been  fo  inclined,  as  Mr.  Leeke  wiflied  to  be  prefent  when 
ihe  was  taken  out  of  the  keddah.  On  the  13th  of  January,  1783,  Mr.  Leeke  went  out, 
when  there  were  only  herfelf,  another  female,  and  eight  young  ones,  remaining  in  the  inclo* 
fure.  After  the  other  female  had  been  fecured,  by  means  of  the  koomkees  f  fent  in  for  that 
purpofcy  the  hunters  were  ordered  to  call  Juggut'-Peaurec.  She  immediately  came  to  the 
fide  of  the  ditch,  within  the  inclofure :  on  which,  (bme  of  the  drivers  were  defired  to  carry 
in  a  plantain  tree,  the  leaves  of  which  flie  not  only  took  from  their  hands,  with  her  trunk, 
but  opened  her  mouth,  for  them  to  put  a  leaf  into  it,  which  they  did,  ftroking  and  careffing 
her,  and  calling  to  her  by  name.  Mr.  Leeke,  feeing  the  animal  fo  tame,  would  not  permit 
the  hunters  to  attempt  tying  her  ;  but  ordered  one  of  the  trained  elephants  to  be  brought  to 
her,  and  the  driver  to  take  her  by  the  ear,  and  order  her  to  lie  down.  At  firft,  (he  did  not 
.  like  the  koomkte  to  go  near  her,  and  retired  to  a  diftance,  feemingly  angry ;  but,  when  the 
iSirivers,  who  were  on  foot,  called  to  her,  flie  came  immediately,  and  allowed  them  to  ftroke 
and  carets  her,  as  before ;  and,  in  a  few  minutes  after,  permitted  the  trained  females  to  be 
Ximiliar.  A  driver,  from  one  of  thefe,  then  faftened  a  rope  round  her  body,  and  inftantly 
jumped  on  her  back;  which,  at  the  moment,  flie  did  not  like,  but  was  foon  reconciled  to  it. 
A  fmall  cord  was  next  &ftened  round  her  neck,  for  the  driver  to  put  his  feet  in,  who,  feating 
liimfelf  on  the  neck,  in  the  ufual  manner^  drove  her  about  the  keddah^  the  fame  as  any  of 
the  tame  elephants. 

After  this,  he  ordered  her  to  lie  down,  which  flie  inftantly  did ;  nor  did  flie  rife  till  flie 
was  defired.  He  fed  her  from  his  feat,  gave  her  his  flick  to  hold,  which  flie  took  with  her 
trunk,  and  put  into  her  mouth,  kept,  and  then  returned  it,  as  flie  was  direAed,  and  as  flie 
formerly  had  been  accuftomed  to  do.  In  fliort,  flie  was  fo  obedient,  that  had  there  been 
more  wild  elephants  in  the  keddab  to  tie,  flie  would  have  been  ufeful  in  fecaring  them. 

Mr.  Leeke  himfelf  then  went  up,  took  her  by  the  ear,  and  bade  her  lie  down ;  a  command 
Ihe  infbmtly  obeyed. 

I  have  known  feveral  other  inftances  (^  elephants  being  taken  a  fecond  time ;  and  wts 
m]rfelf  a  witnefs  both  of  the  efcape  and  retaking  of  one,  as  related  in  the  following  account* 

*  When  elephants  were  fecured  in  the  outlet  from  the  keddaby  they  bruifcd  thcmfclvei  terribly.  Kide 
Afiatic  Rcfearches,  Vol.  Til. 

f  Koomkees  are  female  elephants,  trainc^l  for  the  purpofc  of  fccuring  wild  elephants,  and  more  particularly 
chofc  largt  males  which  ftray  from  the  woods,  named  goondaH,    Ftde  Afiatic  Rcfearches,  VoU  III. 

In 


194  Natural  tiljlory  of  the  Elephant, 

In  June,  1787,  ^attra-MunguU  a  male  elephant,  taken  the  year  before,  was  travelling, 
in  company  with  fome  other  elephants,  towards  Chittigong,  laden  with  a  tent  and  (bnrie  bag- 
gage, for  our*  accommodation  on  the  journey.  Having  come  upon  a  tiger's  track,  whick 
elephants  difcover  readily  by  the  fnell,  he  took  fright,  and  can  off  to  the  woods,  in  fpite  of 
the  efforts  of  his  driver-  On  entering  the  wood,  the  driver  faved  himfelf,  by  fpringing  from 
the  elephant,  and  clinging  to  the  branch  of  a  tree  under  which  he  was  paffing;  when  the 
elephant  had  got  rid  of  his  driver,  he  (bon  contrived  to  (hake  off  his  load.  As  foon  as  he 
ran  away,  a  trained  female  was  difpatched  after  him-,  but  could  not  get  up  in  time  to- prevent 
his  efcape ;  (he,  however,  brought  back  his  driver,  and  the  load  he  had  thrown  ofF,  and  wt 
proceeded,  without  any  hope  of  ever  feeing  him  again. 

Eighteen  months  after  this,  when  a  herd  of  elephants  had  been  taken,  and  had  remained 
feveral  days  in  the  inclofure,  till'  they  were  enticed  into  the  outlet,  there  tied,  and  let  out  m 
the  ufual  manner,  one  of  the  drivers,  viewing  a  male  elephant  very  attentively,  declared  he 
refembled  the  one  which  had  run  away.  This  excited  the  curiofity  of  every  one,  to  go  and 
look  at  him ;  but,  when  any  perfon  came  near,  the  animal  ftruck  at  him  with  his  trunk,  and, 
in  every  refpedt,  appeared  as  wild  and  outrageous  as  any  of  the  other  elephants^ 

At  length,  an  old  hunter,  coming  up  and  examining  him  narrowly,  declared  he  was  die 
vory  elephant  that  had  made  his  efcape  about  eighteen  months  before. 

Confident  of  this,  he  boldly  rode  up  to  him,  on  a  tame  elephant,  and  ordered  him- to  lie 
down,  pulfing  him  by  the  ear  at  the  fame  time.  The  animal  feemed  quite  taken  by  fiirpriie, 
and  inftantly  obeyed  the  word  of  command,  with  as  much  quicknefs  as  the  ropes,  with 
which  he  was  tied,  permitted ;  uttering,  at  the  (ame  time,  a  peculiar  (brill  fqueak  through 
his  trunk,  as  he  had  formerly  been  known  to  do ;  by  which  he  was  immediately,  recc^nizedt 
by  every  perfon  who  had  ever  been  acquainted  with  this  peculiarity. 

Thus  we  fee  that  this  elephant,  for  the  fpace  of  eight  or  ten  days,  during  which  he  was 
in  the  keddah^  and  even  while  he  was  tying  in  the  outlet,  appeared  equally  wild  and  fierce  as 
the  boldeft  elephant  then  taken  ;  fo  that  he  was  not  even  fufpe£led  of  having  been  formerly 
taken,  till  he  was  conduced  from  the  outlet.  The  moment^  however,  he  was  addreffed  in  a 
commanding  tone>  the  recolleftion  of  his  former  obedience  feemed  to  ru£h  upon  him  at  oncej 
and,  without  any  difficulty,  he  permitted  a  driver  to  be  feated  on  his  neck>,  who^.in  a.few 
dajrs,  made  him  as  tractable  as  even 

Thefe,  and  feveral  other  inftances  which  have  occurred,  clearly  evince,  that  elephants 
have  not  the  fagacity  to  avoid  a  fnare  into  which  they  have,  even  more  thaa  once,  fallen. 

The  general  idea,  that  tame  elephants  would  not  breed,  has  doubtlefs  prevented  trials 
being  made,  to  afcertain  whether,  under  particular  circumftances,  this  fuppofed  reluAance 
could  be  got  the  better  of. 

I  was  however  convinced,  from  obfervation,  as  well  as  from  fome  particular  h&s^  that 
depbants  had  their  feafbns  in  which  they  were  in  heat ;  I  fball>  therefore)  firft  mention  the 


Mr.  Bullcr  and  myfelf. 


I 


circum^ 


Natural  HlJIdry  of  the  Elephant.  I9  J 

ciFCumftances  which  induced  me  to  attempt  breeding  from  tame  elephants,  and  then  relate 
the  fuccefs  of  the  experiments  inflituted  for  this  purpofe. 

The  circumftances  to  which  I  allude,  happened  in  January,  17909  at  a  keddah  near  to 
Comillah,  the  capital  of  Tiperah. 

Meffrs.  Henry  Buller  and  George  Dowdefwell,  of  Chittigong,  being  then  on  a  vifit  at 
Comillah,  accompanied  me  and  feveral  others,  to  fee  a  herd  of  elephant^  which  had  been 
lately  taken.  Our  vifitors  then  propofcd  a  trial  being  made,  of  tying  the  wild  elephants  im- 
mediately, in  the  keddah^  in  the  manner  pra(3ifed  at  Chittigong,  inftead  of  waiting  till  tliey 
were  enticed,  one  after  another,  into  the  narrow  outlet,  there  to  be  fecurcd,  and  led  out  in 
the  ufual  manner*. 

This  mode  they  recommended  fo  earneftly,  from  a  conviftion  of  its  fuperior  utility  t>  that 
Mr«  Johnp'Buller,  to  whom  the  keddah  belonged,  afTentcd  to  the  trial  being  made,  and  gave 
orders  for  the  trained  females,  and  proper  afliftants,  to  go  direAly  within  the  inclofure. 
Having  but  few  trained  females  prefent,  it  was  judged  advifable  to  fend  in  a  fine  male 
dephant,  taken  many  years  before,  and  thoroughly  broke  in,  to  afSft  them,  as  well  as  to  keep 
the  herd  in  awe.  He  had  no  fooner  entered  the  inclofure,  and  been  brought  near  the  herd, 
tlun,  difcovering  one  of  the  females  to  be  in  heat,  impelled  by  defire,  and  eager  to  cover 
her,  he  da(hed  through  the  herd,  regardlefs  of  the  orders  and  fevere  difcipTine  of  the  driver, 
and  had  nearly  accompIiQied  his  purpofe.  The  driver,  being  alarmed  for  his  own  fafety, 
exerted  in  vaia  all  his  ftrength,  to  turn  him,  and  bring  him  from  among  the  wild  elephants  ; 
but  the  drivers  of  the  trained  females,  coming  fpeedily  to  his  afliftance,  foon  furrounded  this 
furious  animal,  and  feparated  him  from  the  herd.  In  refentment,  however,  of  his  difap- 
pointment,  he  attacked  a  fmall  koomkecy  with  fuch  violence  as  completely  overturned  her  and 
her  rider ;  and,  had  he  not  been  of  a  particular  fpecies,  called  mucknahy  vrhich  have  only 
fmall  tuiks,  he  moft  probably  would  have  transfixed,  and  killed  her  on  the  fpot :  fortunately, 
neither  (he  nor  her  driver  received  any  conftderabic  hurt.  This  accident  prevented  the  trial 
being  then  made,  to  tie  the  wild  elephants  in  the  manner  propofed« 

JKefledling  on  the  difobedience  (hown  by  an  elephant  remarkably  docile,  and  which  had 

^  /7//^  AHath:  Refearches,  Vol.  ill.  article,  <<  Method  of  catching  wild  Elephants  ^"  where  this  procefs  is 
particularly  dcfcribcd. 

f  Though  fully  convinced  df  this,  I  could  not  bring  the  hunters  to  adopt  the  Chittigong  method,  till  the 
3rcar  i794<  After  this,  during  the  laft  three  years  I  remained  at  Tiperah,  I  did  not  lofc  one  elephant  in 
twenty  ;  whereas,  by  the  former  method,  of  tying  them  in  the  roomee^  near  one-third  of  thofe  taken  died  in 
lefs  tlian  a  year,  in  confcquence  of  the  hurts  they  received  from  their  violent  efforts  to  get  free,  before  they 
rould  be  properly  fecurcd.  The  natives  of  Tiperah,  and  indeed  of  moft  parts  of  India,  are  extremely  at- 
tached to  old  cuftoms  ;  and  it  was  with  the  utmoft  difficulty  I  prevailed  on  the  hunters  to  deviate  from  the 
practice  of  their  anceftors,  though  the  method  Fccommended  was  followed  atSilhct,  as  well  as  at  Chittigong. 
The  method  was,  (imply  to  furround  a  herd,  in  the  firft  convenient  place,  with  a  ditch  and  palifade  ;  and, 
when  this  was  finifhed,  to  fend  in  the  koomkees^  and  proper  perfons  to  tie  the  wild  elephants  on  the  fpot,  and 
tlien  conduct  them,  one  by  one,  through  an  opening  in  the  palifade,  from  the  keddah^  as  foon  as  they  were 
lied. 

been 


iq5  Natural  Hijiorj  of  the  EUpbant. 

been  demefticated  for  many  years,  when  his  paflions  were  excited,  and  recollefting  alio, 
that  a  wild  elephant  had  covered  a-female,  in  February,  1778,  be%e  many  fpe^tors,  juft 
after  the  herd  had  been  fecured  in  the  inclofure,  I  was  aflured  in  my  own  fliind,  that  it  was 
not  from  any  fcnfe  of  modefty,  either  wild  or  tame  elephants  did  not  gratify  their  paffions  in 
public ;  but  no  opportunity  offered  of  {>r(^ecuting  this  inquiry,  till  1792.  Having  then 
taken  upon  myfelf  the  management  of  the  elephant  hunters,  a  very  fine  male  was  caught  in 
November :  he  was  both  young  and  handfome,  and  alfo  of  a  moft  docile  difpofition  \  I  there-* 
fore  promifed  his  driver  a  confiderabli  gratuity,  if  he  would  get  him  into  high  order,  fo  that 
I  might  have  an  opportunity  of  bringing  his  procreative  powers  to  trial,  with  a  tame  female^ 

In  the  month  of  March,  1793,  the  driver  of  a  favourite  female  el.ephant  informed  me^ 
that  (he  had  then  figns  of  being  in  heat ;  and  that,  if  theinale  and  (he  were  kept  together, 
and  highly  fW,  an  intimacy  would  probably  foon  take  place.  They  were  therefore^  fhortly 
after  this,  brought  near  to  Comillah,  where  a  fpacious  (bed  was  ere£ted  for  their  accommo« 
dation. 

'  In  the  day,  they  went  out  together,  to  feed;  they  aUb  brought  home  a  load  of  fuch  fuccu«^ 
lent  food  as  their  drivers  and  attendants  could  colledl.  After  their  return,  they  flood  toge« 
ther,  flept^  near  each  other,  and  every  opportunity  was  granted  them  to  form,  a  mutual  at- 
tachment. In  the  evening,  they  had  each  from  ten  to  twelve  pounds  of  rice  foaked  in  wateri 
to  which  a  little  b\t  was  added ;  and,  from  the  middle  of  May  till  the  latter  end  of  June^ 
fome  warm  ftimulants,  fuch  as  onions,  garlic,  turmeric,  and  ginger,  were  added  to  their 
ufual  allowance  of  rice.  Long  before  this,  however,  a  partiality  had  taken  place,  as  was; 
evident  from  their  mutual  endearments,  and  careifing  each  other  with  their  trunks  i  and  this^ 
without  ceremony,  before  a  number  of  other  elephants,  as  well  as  their  attendants. 

Near  the  end  of  June,  I  was  (atisfied  the  male  would  not,  even  to  regain  his  freedon^ 
quit  the  obje£l  of  his  regard  ;  I  therefore  ordered  the  keepers  to  picket  the  female,  by  one  of* 
her  fore-legs  only,  in  the  houfe  where  they  flood,  but  ta  leave  the  male  at  full  liberty^ 
Fearful,  however,  of  hurting  their  fuppofed  delicacy,  and  thinking  the  nearnefi  and  fight  of' 
the  attendants  might  poffibLy  give  umbrage  to  their  modefly,  I  defired  them  to>  remain  quiet 
in  a  little  hut,  eredled  on  the  outfide  of  the  building  appropriated  to  the  elephants,  where 
they  could  fee  equally  well  as  if  nearer* 

On  the  evening  of  the  28th  of  June,.  1793*,  the  male  was  let  loofe  from  his  pickets ;  and^ 
foon  after,  he  covered  the  female  without  any  difficulty,  although  before  this'ihe  never  could 
have  received  the  male,  being  taken  when  very  young,  about  five  years  and  a  half  prior  ta 
this  period.  The  male  was  then  led  quietly  to  his  flail ;  but,  early  on  the  morning  of  the- 
29*,  he  became  fo  troublefome,  that  the  drivers,,  in  order,,  as  diey  faid,  to  quiet  him,,  but 

•  It  is  alwayi  a  good  fign,  whan  an  cipphant  Itct  down  to  flkcp,  within  a  few  months  after  he  i»  taken  ;  as 
it  ikews  him  to  be  of  a  good  temper,  not  fufpicious,  but  reconciled  to  his  fate.  Elephants,  particularly  gooH^ 
dabs,  have  been  known  to  ftand  twelve  months  at  their  picket?,  without  lying. down  to  flccp  j  though  they, 
innetimes  take  a  ihott  nap  ftandiog. 

gardj;^ 


Natural  Hljlorj  of  tbi  Elepbam.  197 

pfCtAjy  I  fu(pe£t,  to  indulge  their  own  curioiity,  permitted  him  to  cover  her  a  fecond  time ; 
which  he  readily  did,  before  the  ufual  attcndantSi  as  well  as  a  number  of  other  fpe6btors. 
After  tbiSy  the  driver  brought  me  a  particular  account  of  the  whole  proccfs.  Though  much 
pleafed  with  the  fuccefs  of  the  experiment,  yet  I  was  rather  chagrined  he  had  not  given  me 
notice,  that  I  might  have  been  myfelf  an  eye-witnefs  ;  and  therefore  told  him,  he  (hould  not 
receive  the  promifed  reward,  till  I  had  fatisfied  myfelf  of  the  fa6l. 

About  two  in  the  afternoon  of  the  (ame  day,  I  was  deiired  to  repair  to  the  place  where 
the  elephants  flood,  as  the  male  had  been  trying  to  get  nearer  the  female.  On  this,  I  pro- 
cetded  to  the  fpot,  with  my  friend  captain  Robert  Burke  Gregory :  when  we  arrived,  I 
ordered  the  male  to  be  freed  from  his  fliackles ;  and,  after  fome  toying,  and  a  few  mutual 
carefles,  we  had  the  fatisfadion  to  fee  him  cover  the  female. 

When  the  male  mounted,  he  placed  one  of  his  fore -legs  on  each  fide  of  her  fpine,  with 
hit  feet  turned  to,  and  preffing  againft,  her  flioulders,  and  his  trunk  over  her  forehead  ;  fup* 
porting  himfdf  firmly  in  this  fituation,  during  coition,  which  he  continued  nearly  the  fame 
time,  and  in  the  fame  manner,  as  a  horfe  with  a  mare. 

The  female  remained  perfe£Uy  ftill,  during  the  coitus.  When  the  male  had  (iniOxcd,  he 
flood  quietly  by  her  fide,  while  (he  cartfied  him  with  her  trunk ;  and,  as  they  then  appeared 
well  pleaied,  and  gentle  as  ufual,  I  went  up  and  patted  them  bott^  as  I  had  formerly  been 
accuftomed  to  do,  without  the  fmalleft  apprehenfion.  In  the  evening,  they  were  brought 
borne  to  be  fed ;  and,  though  only  a  few  hours  had  elapfed  fince  his  laft  embrace,  the  male 
feemed  inclined  to  nuke  another  attempt;  to  which  I  would  have  confented,  to  gratify  a 
crowd  of  people  then  prefent,  had  1  not  now  learned,  that  he  had  covered  the  female  in  the 
open  plain,  about  ten  in  the  morning,  when  going  out  for  food,  in  fpite  of  the  exertions  of 
the  drivers  and  attendants  ;  at  lead  fo  they  alleged,  in  excufe  for  having  permitted  it,  con- 
trary to  my  orders*  As  be  had  already  covered  four  times  in  about  firteen  hours,  I  was 
afraid  a  further  indulgence  might  be  prejudicial,  and  therefore  woulJ  not  permit  it ;  efpecially- 
as  Mr.  ImhoflT,  to  whom  he  then  belonged,  was  abfent.  That  gentleman,  however,  re- 
turned  two  days  after :  but,  when  the  two  elephants  were  brought  together,  in  order  that  Mr. 
ImhoiTs  curiofity  might  be  indulged  with  fo  novel,  a  fight,  the  female,  being  no  longer  in 
heat)  was  fo  uncivil  as  to  give  the  male  a  kick  in  the  face,  when  he  was  ufmg  what  (he  then 
thought  improper  liberties ;  nor  did  (he  afterwards  permit  him  to  cover  her,  though,  whe» 
ftanding  together,  they  mutually  indulged  in  a  few  carefles. 

{T9  bi  continuid.) 


Vol,  III.— \ucusT  1799.  Dd  Dfrfp^ 


15S  Admiafurenunt  of  the  Stringth  df  Gunf^wdir* 

•  -  • 

III. 

Dffcrptlon  and  Vf.  of  a  portable  Inflrumcnt  for  comparing  the  Force  of  Gunpowder*     By 

Gtizen  Recnier  *. 


I 


N  proceflcs  for  the  improvement  of  gunpowder,  it  is  neceffary  to  make  comparative  expe* 
riments.  Different  contrivances,  exhibiting  various  degrees  of  ingenuity,  have  been  made 
ufe  of  for  this  purpofc,  which  are  too  well  known  to  require  defcription  in  this  place.  I 
{ball,  therefore,  only  remark,  that  trials  of  gunpowder,  on  a  large  fcale,  are  always  the  beft| 
but  as  thefe  experiments  require  apparatus^  and  conveniences,  which  are  not  in  the  power  of 
every  one,  a  fmall  powder-proof  has  long  fince  been  received  and  commonly  ufed,  which  \%- 
conftruded  in  the  form  of  a  piflol,  the  blaft  from  which  drives  a  fmall  toothed,  or  turned, 
wheel,  which  rubs  againft.  a  fpring,  and  is  moved  through  a  greater  or  lefs  fpace,  according 
to  the  force  of  the  powder.  But  this  machine,  which  is  very  defedlive  in  its  refults,  and  can 
be  of  no  value  when  an  abfplute,  or  at  leaft  approximate,  indication  is  required  of  the 
relative  forces  of  a  given  meafure  of  powder  intended  for  fire-arms,  which  are  charged  with 
quantities  determined  in  that  manner. 

In  fa£l,  thefe  proof  inftrumcnts  have  an  arbitrary  graduation.  Their  fridion  varies  ac- 
cording to  the  force  of  the  fpring,  and  the  cleannefs  or  oxydation  of  the  mechaniim. 

I'o  obviate  thefe  different  inconveniencel,  I  made  a  number  of  experiments*  which  led  me 
to  a  more  valuable,  and,  in  fad,  a  much  more  accurate  principle ;  and,  at  length,  with  fome  , 
modifications,  I  adapted  a  fmall  brafs  cannon  to  the  fpring  of  the  common  weighing  inftru- 
ment.  By  this  application,  I  immediately  acquired  the  means  of  weighing  the  efibrt  of  the 
blaft,  and,  confequently,  a  comparable  method  of  eftimating  its  action.  This  machine  has* 
like  wife  the  valuable  property  of  operating  without  friSion.     lu  graduation  is  juftly  deter- 

*  From  M^moires  explicatifs  du  Dynamometre  et  autre  Machines  iDvent^ei  par  le  C.  Regnier.  36  Pages, 
in  Quarto,  printed  at  Paris  in  the  Year  VII.  The  inftruments  dcfcibtd  in  this  pamphlet  are  ;  i.  The  dy- 
namometer, which,  bj  means  of  apparatus  connected  with  a  ftrong  fpring,  meafures  the  rea6Hon  exerted  againil 
the  powers  of  men,  horfcs,  and  other  agents,  at  work.  2.  A  fafeguard  tfor  the  priming,  in  mufketry.  Tc 
coofifts  of  a  cylindrical  piece  in  brafs,  out  of  which  the  cavity,  or  pan  for  holding  the  priming,  is  excavated, 
and  another  hollow  cylindrical  piece,  which  covers  the  firft,  and  is  cut  through' la  fuch  manner  as  to  prefent 
an  opening  correfponding  with  that  of  ^he  pan.  When  this  hollow  cylinder  is  fo  difpofed,  that  the  two  open* 
ings  correfpond,  the  muiket  may  be  difcharged ;  but  when,  by  turning  the  external  part  half  round,  the 
pan  becomes  completely  covered,  the  priming  is  very  fecure^  and  the  piece  cannot  be  difcharged  either  by 
accident  or  de(ign.  3.  The  powder- proof,  which  is  the  fubje^  of  the  prefent  article  ;  and,  4.  An  electrical 
machine.  This  machine  operates  by  the  friction  of  a  circular  plate.  The  principal  Angularity  of  this  ap. 
paratus,  is  the  condu^or,  which  is  not  cylindrical,  but  hai  the  form  of  a  flat  table,  with  thick  rounded  edges 
to  prevent  the  efcape  of  the  electric  fluid.  A  plate  of  coated  glafs  it  attached  to  the  lower  furface,  which 
anfwers  the  fame  purpofes  of  convenience  and  advantage,  as  the  jart  which  Naime  put  into  cylindrical  con« 
dudors  about  flxteen  years  ago.  Eledriciani  will  not  require  that  the  conveniences  of  the  flat  condu^r,  or 
cab!ei  fliould  be  here  pointed  out.    ^. 

mincd| 


Portable  Pnvder'-prtof.  199 

•    ■        ■  .  ...  . 

mined,  becaufe  It  exprcflcs  the  weight  which  fervcd  for  its  graduation,  and  the  inftrument 

tiiay  liicewifebe  ufefully  applied  for  weighing  fuch  bodies  as  fall  within  the  limits  of  its  fcale. 

The  little  attention  I  paid  to  render  this,  inftrument  public,  and  the  prejudice  which,  in 
Hioft  cafes,  gives  a  preference  to  things  brought  from  foreign  countries,  have  caufed  it  to  be 
defignated  as  the  Englifli  or  German  powder-proof  j  but  the  faft  is,  that  I  invented  it  my- 
felf  in  Burgundy,  where,  in  the  time  of  the  academy  of  Dijon,  it  was  conlidered  as  the  beft 
inftrument,  on  a  fmall  fcale,  for  determining  the  ftrength  of  gunpowder. 

Defcription.  Plate  IX.  fig.  I.  A.  A  perfpedlive  view  of  the  inftrument.  B.  C.  A  fpring 
bended  into  an  angle.  D.  A  fmall  cannon  of  brafs,  containing  exaftly  a  gramme  of  fine 
gunpowd.er  (15  J  grs).  E.  Arc  of  divifion  graduated  into  kilogrammes  (nearly  albs  and 
a  quarter  avoirdupois  each),  terminating  in  a  fcrew,  which  fcrves  as  the  breech-pin  to  the 
cannon.  F,  A  cap,  which  may  be  confidered  as  the  projedlile.  It  clofes  the  mouth  of 
the  fniall  cannon,  upon  which  it  prefles  with  a  force  equal  to  four  kilogrammes.  This 
ftopper  is  firmly  fixed  to  one  of  the  fpring  radii,  by  means  of  a  nut  at  the  oppofitc  end  of  its 
branch  or  tail.  G.  A  piece  of  hard  brafs  wire  fixed  to  a  projedion,  rivetted  into  one  of  the 
radii,  by  means  of  a  fmall  fcrew.  H.  An  index  of  woollen  cloth,  or  leather,  which  Aides 
by  a  gentle  fridlion  upon  the  wire,  when  the  branches  of  the  fpring  are  preffed  together  by 
the  inflammation  of  the  powder.  This  index  remains  at  the  place  to  which  it  has  been 
puftied,  and  ftiews  precifely  the  diftance  to  which  the  fprings  have  been  made  to  approach. 

Method  of  ufing  this  inftrument  i.  The  two  extremities  of  the  fpring  are  to  be  preflTcd 
together,  in  order  to  feparate  the  cap  from  the  mouth  of  the  fmall  caimon.  2.  Powder  is 
poured  either  by  means  of  card  or  paper  into  the  cannon,  fo  as  exadtly  to  fill  it;  the  ftopper  is 
then  fulFered  to  apply  itfelf  gently  to  the  muzzle,  and  clofe  it  cxaftly,  without  leaving  any 
grain  of  powder  between  them.  3.  The  circular  piece  of  cloth,  or  leather,  which  ferves  as 
the  index,  muft  be  moved  into  contaft  with  that  branch  of  the  fpring,  to  which  the^  tail 
of  the  ftopper  is  fixed.  4.  Priming  being  then  put  into  the  fmall  pan  of  the  cannon,  it  muft 
be  difcharged,  holding  the  inftrument  fufpended  by  the  ribband  or  ftring  which  is  pafFciT 
through  the  angular  bend. 

The  eflFcfts  of  the  explofion  are,  that  the  powder  occupying  a  greater  fpace  by  its  inflam- 
mation, drives  back  the  ftopper,  which  carries  with  it  that  branch  of  the  fpring  in  which  its 
fail  is  firmly  fixed.  This  branch  cannot  move  relatively  to  the  other,  which  is  alfo  moved  by 
the  recoil  of  the  gun,  without  driving  before  it  the  fmall  index  piece,  and  the  fpace  through 
which  this  is  carried  will  ftiew  the  force  of  the  powder. 

The  arcs  moved  through  by  the  explofion  of  different  famples  of  powder,  will  fliew,  by  the 
numbers  of  their  graduations,  the  comparative  forces  of  each.  There  is  a  ftar  marked  ou 
the  graduated  arc  which  fliews  the  force  of  powder  of  a  medium  quality,  in  order  that  t.ic 
relative  value  of  any  fa«nplc,  with  regard  to  that  medium,  may  be  known.  The  friction 
of  the  index,  is  the  only  friftion  to  which  this  inftrument  is  fubjedl,  and  this  is  fo  flight,  that 
il  may  be  confidered  as  nothinj.     The  index  itfelf  may  be  eafily  renewed  when  worn  out. 

Dd2  It 


200  ExpninwUt  U  sfctrUin  * 

It  is  obviousi  that  by  adding  a  book  to  die  perforation  at  the  extremity  of  the  divided  are, 
and  a  ring  in  the  eye  of  the  ftopper,this  inftrument  may  be  ufed  for  weighing :  the  dirifiont 
are  half  kilogrammes;  (they  might  conveniently  be  pounds  avoirdupois). 


s« 


IV. 

An  Account  of  fome  Endeavours  to  afcertain  a  Standard  of  Weight  and  Meafure.    By  Sir 
George  Shuckburqh  Evelyn^  Bart.  F.R.S.  and  A,S.     Continued  from  p.  157. 

\i'  35v  J|[  HE  chief  ftandards  of  longitudinal  meafure,  as  far  as  I  can  learn,  that  carry 
any  authority  with  them,  are  thofe  prcferved  in  the  exchequer  ;  in  the  houfe  of  commons  ;  at 
the  Royal  Society,  and  in  the  Tower.  The  firft  alone,  indeed,  bear  legal  authority,  and 
4}avc  been  in  ufe  for  more  than  200  years  ;  the  lad  is  confidered  as  a  copy  of  ^em,  and  is 
not  ufed  for  fizing  generally.  The  two  remaining  ones  are  of  modern  date ;  and,  although 
they  do  not  carry  with  them  at  prefent  any  ftatuteable  authority,  yet,  from  the  high  repuu- 
tion  and  acknowledged  care  of  the  artifts  who  made  them  (the  celebrated  Mr.  George 
Graham,  and  Mr.  John  Bird),  are  undoubtedly  entitled  to  very  great  refpeft ;  and  are  pro- 
bably derived  from  a  mean  refult  of  the  comparifons  of  the  old  and  difcordant  ones  in  the 
exchequer.  I  (hall  begin  with  that  of  Mr.  Graham,  which  comains  aHb  the  length  of  the 
Tower  ftandard  laid  down  upon  it;  will  proceed  then  to  Mr.  Bird's,  and  finally  conclude 
with  thofe  at  the  exchequer. 

(§.  36.)  May  5,  1797.  I  went  to  the  apartments  of  the  Royal  Society,  at  Somer(et 
Houfe,  and,  with  the  ready  aflidance  of  Mr.  Gilpin,  at  the  kind  inftance  of  fir  Jofeph 
Banks,  I  made  the  following  obfervations  on  Mr.  Graham^s*  brafs  flandard  prd,  made  in 
1742.  This  fcale  is  about  42  inches  long,  and  half  an  inch  wide,  containing  three  parallel 
lines  engraven  thereon,  on  the  exterior  and  ulterior  of  which  are  three  divifions,  expreffing 
feet,  with  the  letter  £  at  the  lafl  divifion ;  and,  by  a  memorandum  preferved  with  it  in  the 
archives  of  the  fociety,  is  faid  to  fignify  Englifh  meafure,  as  taken  from  the  ftandard  in  the 
Tower  of  London.  That  with  the  letter  F  denoting  the  length  of  die  half  of  the  French 
toife,  put  on  here,  by  the  authority  and  under  the  infpe£tion  of  the  Royal  Academy  of 
Sciences,  then  fubfifling  at  Paris,  to  whom  it  was  fent  in  1742,  for  the  purpofe  of  comparing 
the  French  and  Englifh  meafures.  The  middle  line,  marked  Exch.  of  the  three  abovemen« 
tioncd,  denotes,  as  is  fuppofed,  the  flandard  yard  from  the  exchequer. 

(§.  37.)  This  bar  of  Mr.  Graham's  had  been  previoufly  laid  together  with  my  (cale  divided 
by  Mr.  Trough  ton,  for  twenty-four  hours,  to  acquire  the  fame  temperature;  diey  were  alfb 
of  the  fame  metal,  and,  by  placing  it  under  my  microfcopes,  adjufted  to  the  inteifval-  between 

10  and  46  inches,  I  found  the  interval  on  die  Tower  ftandard  exceed 

*  Th*s  rod  was  not  made  by  Mr.  Graham,  but,  at  hit  indance,  procured  by  him  from  Mr.  Jonathan  Siflbn, 

11  cckbr&tcd  aniH  of  that  time.    See  Phil.  Tranf.  Vol.  JCLII.     ' 

nin^ 


4  Standard  »/  Weight  and  Mtafun.  2ot 

inchei. 

mine,  hy  ^^m  0,00127' 

>ooi28  ^  =  the  total  length  therefore  36,00130  inches>  the  therm,  at  60^,8; 

Mean  s    900130^ 
The  interval  on  the  line  marked  Exch.  was  fiiorter  than  mint 

inches. 

by  -  — ,oo66T 

*oo68  I  =  the  total  Jength  =  35^9933  inches,  the 
'  I     therm,  at  60^,6. 

>oo67^ 
And  the  Paris  half-toife^s which  had  been  fuppofed  by  the  Academy  to  be  =  389355  Engjiflt^ 
inches,  was  found,  compared 

inches.  inches.^ 

with  mine,  tobe  =  38,3561! 

,3563  X  Mean  =s  38,3561  *. 

>3S593. 

^  Dr.  Maikelyne  fays,  this  ilandard  yard  of  Mr.  Graham's  was  ^^  inch  longer  on  three  feet  than  Mr." 
Bird's  divided  fcale,  which  he  generally  made  ufe  of  in  all  his  operations  of  dividing  ;  and,  from  one  made 
coikformakly  to  this  of  Mr.  Bird's,  Mr.  Troughton  divided  my  fcale  of  60  inches.  This  remark  feems  to 
agree  with  my  ift  and  3d  comparifon,  but  not  with  the  intermediate  one.  See  Phil.  Trinf.  for  1768,  p.  324. 
As  I  am  now  upon  the  fubjedt  of  foreign  meafure,  it  may  not  be  quite  out  of  place  to  fay  a  word  on  the 
length  of  the  ancient  Roman  foot,  which  I  am  enabled  to  du  with  feme  precifion. 

Some  years.ago,  when  I  was  in  Italy,  I  had  feverai  opportunities  of  afcertaining  the  length  of  this' mcafurf , 
by  actual  examination  of  the  Roman  fo«t  rules,  of  which  I  have  met  with  nine,  vie.  two  in  the  Capitol  at 
Rome ;  one  in  the  Vatican  ;  five  in  the  mufeum  at  Portici,  near  Naples  ;  and,ia(lly,  one  in  the  Britiih  mufcum, 
icnt  from  Naples  by  fir  William  Hamilton.  They  were  all  of  brafs,  except  one  half- foot,  of  ivory,  with  a 
joint  in  the  middle,  refembling  our  common  box  or  ivory  rules :  and,  by  reference  to  my  journal  kept  at  that 
time,  I  find  the  mean  refult  from  all  the  nine  rules,  viz.  by  taking  both  the  whole  and  the  parts  of  each  (for 
they  were  divided  into  12  inches,  and  alfo  into  i6ths,  or  digits),  gave,  for  the  length  of  the  old  Roman  * 
foot,  in  Englilh  inches,  correfpondent  to  Mr.  Bird's  meafure,  =  11,6063. 

In  confirmation  alfo  of  this  conclufion,  and  agreeably  to  the  idea  of  M.  de  la  Condamine,  in  thr  '*  Jdumat 
of  hta  Tour  to  Italy,"  I  took  the  dimenfions  of  feverai  ancient  buildings,  viz.  the  interior  <liameter  of  the 
temple  of  Vefta  ^  the  width  of  the  atch  of  Sevcrus  -,  the  door  of  the  Pantheon  ;  and  the  width  of  the  bafe 
ef  4he  qnadrilatcral  pyramid  of  Ceftias,  which,  it  is  curious  to  obfcrvcy  I  found  exa£Uy  100  old  Roman  feet,  . 
tmd  11$  feet  high.    This  I  do  not  remember  to  have  feen  noticed  by  any  fanner  traveller. 

The  mean  refult  of  thefe  experiments  gave  me  ....       11,617  Engliih  inches. ^- 

Ditto,  as  before,  from  the  rules  -  •  •  -  11,606  ditto. 

The  mean  of  the  two  modes  of  determination  11  -  -  -  11,612  ditto.- 

I  may  add,  that  in  the  Capitol  is  a  ftone,  of  no  very  ancient  datehowrrer,  let  into  the.  wall,  on  which  o  -^ 
engraven  the  length  of  feverai  meafores,  from  whence  I  took  the  following  : 

The  ancient  Roman  foot,  =  11,635  Englilh  inches. 

The  modem  Roman  palm,  s=»    8,82    ditto.  «».;} 

The  accient  Greek  ftot,  -»  12,09    ^i^^*- 


202  Experiments  to  afcertaln 

inches. 

The  I  ft  of  the  preceding  obfervations  giving  -  -  w  •  36,0013 

Thc^d  -  -  -  .  .  -  3S>9933 

The  mean  length  of  Mr.  Graham's  (landard  becomes  .  •  -  3S>9973 

(§•  38')  From  the  information  in  the  report  of  a  committee  of  the  houfe  of  commons, 
that  fat  in  the  year  1758,  I  learnt  that  Mr.  Bird's  parliamentary  ftandard  had  been  in  the 
cuftody  of  fome  of  its  officers,  but  of  whom  nobody  knewi  however,  under  the  authority 
of  the  fpeaker,  who  was  fo  good  as  to  furniAi  me  with  a  room  in  his  houfe,  to  make  the 
comparifons  in,  I  at  "laft  difcovered  this  valuable  original  in  the  very  fafe  keeping  of  Arthur 
Benfon,  efq.  clerk  of  the  journals  and  papers,  and  which,  I  believe,  had  never  feen  the  light 
for  five-and-thirty  years  before.     It  is  a  brafs  rod  or  bar,  about  39  inches  long,  and  i  inch 


fquare,  inclofed  in  a  mahogany  frame,  infcribed  "  ftandard  ^^  I7S8;"  at  each  extremity  of 

Geo.  zd. 

it  is  a  gold  pin,  of  about  t'tt  ii^^h  in  diameter,  with  a  central  point,  and  thefe  points  are 
diftant  =  36  inches.  It  bears,  however,  no  divifions ;  but  there  was  found  with  it,  in 
another  box,  a  fcale  divided  into  36  inches,  with  brafs  cocks  at  the  extremities,  for  the  pur- 
pofe  of  flzing  or  gauging  other  fcales  or  rules  by.  Beftdes  thefe,  I  found  another  ftandard, 
in  fize,  and  in  all  refpeds,  flmilar  to  the  laft,  infcribed  1760,  having^been  made  for  another 
committee,  that  fat  in  that  year ;  this  alfo  was  accompanied  with  a  fimilar  divided  fcale  of  36 
inches. 

Thefe  bars  being  too  thick  to  be  conveniently  placed  under  the  microfcopes  of  my  inftru- 
ment,  the  interval  of  36  ftandard  inches  was  laid  down  on  my  fcale  with  a  beam-compafs, 
two  fine  points  made,  and,  compared  with  Troughton's  diviflons,  was  =  36,00023  inches  ; 
-the  thermometer  being  at  64^*  I  then  e^mined  the  other  ftandard,  marked  <^  ftandard, 
1760,"  and  found  it  to  agree  exadlly  with  that  of  1758  ;  at  leaft  it  did  not  differ  from  it 
more  than  ,0002  inch  *. 

(§•  39.)  I  was  now  to  examine  the  old  ftandards  kept  in  the  exchequer :  thefe  Mr. 
Charles  Ellis,  deputy  chamberlain  of  fhe  tally  court  at  the  receipt  of  the  exchequer,  was  fo 
good  as  to  fupply  me  with  ;  viz.  the  ftandard  yard  of  the  30th  of  Eliz.  1588,  and  alfo  the 
ftandard  ell  of  the  fame  date.  Thefe  are  what  have  been  conftantly  ufed,  and  are  indeed  the 
•only  ones  now  in  ufe,  for  iizing  meafures  of  length  f.  They  are  made  of  brafs,  about  0,6 
inch  fquare,  and  are  very  rudely  divided  indeed,  into  halves,  quarters,  eighths,  and  fix- 
teenths;  the  lines  being  two  or  three  hundredths  of  an  inch  broad,  and  not  all  of  them  drawn 
fquare,  or  at  right  angles  to  the  fides  of  the  bar,  fo  that  no  accuracy  could  poffibly  be  ex- 
pefted  from  fuch  meafures.  However,  the  middle  point  of  thefe  trtnfverfe  lines,  between 
^the  fides  of  the  bar,  was  taken  as  the  intended  original  diviiion ;  and  thefe  divifions,  fuch  as 

*  Thefe  quantities  then  being  fo  fmall,  I  ihall  cofifider  them  as  wholly  infcit^Ie  j  and  (hall  fay,  that  Mr. 

Bird's  parliamentary  ftandards  of  3  feet  exactly  correfpond  with  Mr.  Troiightoii's  fcale. 

t  There  was  alfo  a  ftandard  yard  of  Heniry  VII.  but  uf  very  rude  ^orkmanftiip  indeed ;  now  quite  laid 

.  Jby,  And  at  what  time  laft  ufed,  no  information  remains :  but  of^his  more  hereafter. 

tJicy 


a  Standard  9/  TTesght  and  Mtafure^  203 

they  Were,  were  transferred,  by  a  dividing  knife,  to  the  reverfe  fide  of  my  brafs  fcale  made 
by  Mr.  Troughton,  the  thermometer  being  at  63°;  and,  at  my  Icifure  afterwards,  I  fon  id 
as  follows. 

The  ends  of  thefe  venerable-  ftandards  having  been  bruifed  a  little,  or  rounded,  in  the 
courfe  of  fo  many  years*  ufage,  I  conceived  a  tangent  to  be  drawn  to  the  moft  prominent 
part,  which  was  about  the  centre  or  axis  of  the  bar,  and  this  point  being  referred  to  Trough- 
ton's  fcale,  between  6  and  42  inches,  the  entire  yard  of  1588,  meafuring  from  one  extremity 
to  the  other,  was  found  to  be  fhorter  tlian  this,  by  —^007  inch :  but  thefe  comparifons  will 
be  better  exhibited  in  a  table. 


Exchequer  ftaiidard  of  15S8. 


Entire  yard 

[-  yard,  from  24  to  42  inches 
\  yard,  from  15  to  42  inches 
\  yard,  from  i  o\  to  42  inches 
IJ  yard,  from  8 J  to  42  inches 
Entire  ell,  from  2  to  47  inches 
I  ell,  from  2  to  24  [  inches 
I,  from  2  to  35^  inches 
J,  from  a  to  41,37^;  inches 
4- J,  from  2  to  44,1875  inches 


Difference 

Difference 

from 

Lcnirih  in 

on  36 

Trough - 

inches. 

inches. 

ton. 

Inches. 

—  ,007 

35»993 

—  ,007 

+  >o63 

18,063 

+  ,126 

—  ,008 

26,992 

—  ,ou 

+  ,022 

Ji-Saa 

+  ,025 

—  >o55 

33*695 

—  >o59 

—  ,036 

44,964 

—  ,029 

+   >032 

22.532 

+  .052 

+  ,017 

33.767 

+  ,018 

,001 

39»374 

—  ,001 

+  ,051 

42,239 

• 

+  /043 

Mean  difference  on  36 
inches. 


Inches. 
=  +  0,015 


I  =  +  0,016 
i  viz.  the  exchequer 
1  meaiure  v»  by  lb  nnich 
J  the  longer,  or  'about 
I  in  2312. 


(§.  40*}  It  appears  then,  from  the  above  table,  that  the  ancient  ftandards  of  the  realm 
differ  very  little  from  thofe  that  have  been  made  by  Mr.  Bird,  or  Mr.  Troughton,  and  confe- 
quently,  even  in  a  finance  view  (if  one  might  look  fo  fa/  forward),  nothing  need  be  appre- 
hended, of  lofe  in  the  cuftoms,  or  excife  duties,  by  the  adoption  of  the  latter. 

(§.  41.)  I  (hall  now  endeavour  to  (hew  the  proportion  of  the  weights  ihat.I  have  ufed, 
compared  with  the  ftandards  that  were  made  by  Mr.  Harris,  aftay  mafter  of  the  mint,  under 
the  orders  *  of  the  houfe  of  commons,  in  the  year  1758.  They  are  kept  in  the  fame  cuftojy 
with  Mr.  Bird's  fcales  of  length,  and  appear  to  have  been  made  with  great  care,  as  a  mean 
refult  from  a  great  number  of  comparifons  of  the  old  weights  in  the  exchequer,  which  have 
been  detailed  at  length  in  that  report.  Mr.  Harris  having  been  of  opinion  that  the  troy 
pound  was  the  beft.  integer  to  adopt,  as  the  ftandard  of  weight,  I  venture  to  conclude  that 
diis  was  the  moft  accurate,  and  moft  to  be  depended  upon,  of  all  the  various  weights  and 
duplicates  that  he  made  for  the  ufe  of  this  committee  ;  for  he  made  them  of  i,  2,  4,  8,  16, 
lb.  and  of  i-,  i,  2,  3,  6  ounces.  It  will  therefore  be  fufEcient  for  my  purpofe,  to  compare 
the  I  and  2  pounds  troy,  and  their  duplicates,  with  the  weights  of  Mr.  Troughton. 

I  did  this,  June  2d,  1797  ;  the  barometer  being  at  29,72  inches^  and  thennometer  6;^ 

*  See  the  report  referred  to  in  the  note  of  page  106. 

The 


V 


»04 


ExpifimifiUU  afcenih 


'Trou|liltti*t  weightf. 
lb.  graini.  graiiii« 


The  ftandard  weight  of  i  troy  pound,  or  $^60  erains,  marked!  _  ^         -j 

1758,  kept  at  the  houfe  of  commons,  in  a  fmall  box  by  itfelf,>  ""      ^^'^  >  =  S763j74S 
by  Mr.  Bcnfon,  weighed  -  -  -  •J 

A  duplicate  of  the  preceding,  kept  with  fome  odier  weights*  in  a7  =  i  3,70 7  —  <-6,  go- 
box  marked  B  -  -  .  .      5         1675-^^^'   > 

The  mean  weight  of  the  troy  pound,  from  thcfe  two 


The  two-pounds  weight,  from  the  houfe  of  commoni,  kept?  ^^ 
in  A  deal  box,  marked  A  -  --  -  5  "* 


- 

=  576317 » J 

lOOOO 

1000 

400 

100 

20 

►  5=  115*7,84 

7 

0,84. 

> 

lOOOO   * 

1000 

400 

zoo 

20 

►  =  ii5*7»$S 

7 

» 

J 

s  11517,70 
S763.«S 

A  duplicate  of  the  la(l*mentioned  lib.  weight,  pre(erved  in  a  deal 

box,  marked  B  -  *  -  * 

The  thermometer  now  ftood  at  68^. 


Therefore  the  mean  weight  of  alb.  troy,  from  die  two  laft  trials,  is 

And  confequently  lib.  becomes  -  -  - 

'But,  from  the  examination  of  the  two  fmgle  pound  weights,  as  above,  i  pound  is    5763,71  * 

Therefore  the  mean  of  all  is  -  -  -  -  =  5763,78 

That  is,  Mr.  Troughton's  weights  are  too  light  by  f^/^o^  -  =s    «,^56a 

.grain  on  1000  grains,  or  I  in  1523,92  grains. 

(§.  42).  In  condufion,  it  appears  dien  that  the  difference  of  the  length  of  two  pendulums, 
iTuch  as  Mr.  Wbitehurft  ufed,  vibrating  42  and  84  times  in  a  minute  of  mean  time,  in  the 
latitude  of  London,  at  113  feet  above  the  level  of  the  fea,  in  the  temperature  of  60^,  and 
the  .barometer  at  30  inches,  is  =  59189358  inches  of  the  parliamentary  ftandard  i  from 
whence  all  the  meafures  of  fuperficies  and  capacity  are  deducible. 

That,  agreeably  to  the  fame  fcale  of  inches,  a  cubic  inch  of  pure  dtftilled  water,  whetl 
the  barometer  is  29,74  inches,  and  thermometer  at  66^,  weighs  2^2,422  parliamentary 
^grains;  from  whence  all  the  other  weigtits  may  be  derived. 

As  a  fummary  of  what  has  been  done,  I  hope  it  may  now  be  fiud,  that  we  have  attained 
Acfe  three  objedls  5 

ift.  An  invariable,  and  at  all  times  communicable,  meafure  of  Mr.  Bird*s  fcale  of  length, 
now  prefer ved  in  the  houfe  of  commons  $  which  is  the  fiune,  or  agrees  wiihin  an  inicndble 
quantity,  with  the  ancient  ftandards  of  the  realm. 

2dly.  A  ftandard  weigHt  of  the  fiune  chara£ler,  with  reference  to  Mr.  Harris's  troy  pound. 

3dly.  Befides  the  quality  of  their  being  invariable  (withtut  deec^ion),  and  at  aU^  times 

com- 


IfVtghts  and  Afeafures.'^Nnu  Pendulum.  ao5 

^communicable,  diefe  ftandards  will  have  the  additional  property  of  introducing  the  leaft  pof- 
fible  deviation  from  ancient  practice,  or  inconvenience  in  modern  ufe. 

(§.  43.)  Before  T  dofe  this  paper,  after  having  faid  fo  much  on  the  fubjed  of  weights  and 
laeafures,  it  may  not  be  improper  to  add  a  few  words  upon  a  topic  that,  although  not  imme- 
diately conneded,  has  fome  affinity  to  it;  I  mean  the  fubjed  of  the  prices  of  provifions,  and 
of  the  neceflaries  of  life,  &c.  at  different  periods  of  our  hidory,  and,  in  confcqucnce,  the  de- 
preciation of  money.  Several  authors  have  touched  incidentally  upon  this  queilion,  and 
fbme  few  have  written  profclfedly  upon  it ;  but  they  do  not  appear  to  me  to  have  drawn  a 
diflin£t  conclufion  from  their  own  documents.  It  would  carry  me  infinitely  too  wide,  to 
give  a  detail  of  all  the  &(£ts  I  have  colleded ;  I  fhall  therefore  content  myfelf  with  a  general 
table  of  their  refults,  deduced  from  taking  a  mean  rate  of  the  price  of  each  article,  at  the 
particular  periods,  and  afterwards  combining  thcfe  means,  to  obtain  a  general  mean  for  the 
depreciation  at  that  period ;  and  laftly,  by  interpolation,  reducing  the  whole  into  more  regu- 
lar periods,  from  the  conqucfts  to  the  prefent  time:  and,  however  I  may  appear  to  defcend 
below  the  dignity  of  philofophy,  in  fuch  ceconomical  rcfcarches,  I  trufl  I  (hall  find  favour 
with  the  hiflorian,  at  leafl,  and  the  antiquary  *. 

(The  author* s  appendix  hereafier.) 

ifc'  ,  '  .J.  N  ■  >  '  '.  ■ 

V. 

Dtfcriptian  of  a  new  Arrangemtnt  of  the  Bars  in  the  Gridiron  Pendulum.     Tflth  a  Drawing. 

(/T.  N.) 


F 


IG    2,  3,  4>   &c.    in   plate  IX.    reprefent  a  pendulum  which   I    conftrufted    fbme 
months  ago.     It  differs  only  in  the  arrangement  from  the  modern  gridiron  pendulum  of  fire 
bars.     The  fame  letters  denote  the  fame  parts  in  all  the  figures.     A  A  is  a  cylindrical  box 
of  brafs,  filled  with   lead,  conflituting  the  principal   mafs  of   the  pendulum.     In  fig.  4  a 
fcQion  of  this  piece  is  feen  in  the  feftion  of  its  axis.     A  piece  of  brafs,  P  P  P  P,  is  let 
dirough  the  middle  of  this  cylinder  and  firmly  fecured  by  a  flanch  piece  fcrcwed  to  the  brafg 
face.     Two  holes  are  made  quite  through  the  cylinder,  and  the  piece  of  b?afs  P  P,  parallel 
to  the  diameter  of  its  face,  for  the  purpofe  of  fufFering  the  two  fleel  rods  B  B  to  pafs  through. 
Two  fleel  pieces,  L  and  M  N  O,  arc  filled  to  fquare  cavity  in  the  piece  P  P.     Thefe  pieces, 
of  which  fig.  7  gives  a  vertical  fedion,  and  fig.  8  the  fedion  parallel  to  the  horizon,  are  ap- 
plied together,  by  paffing  the  fcrew  M  through  the  end  hole  in  L,  and  then  fere  wing  on  the? 
milled  head  or  nut  K,  in  which  fituation  the  two  fleel  pieces  fit  the  fquare  hole ;  the  vertical 
hole  in  L  being  applied  over  the  long  hole  N,  and  nearly  coinciding  with  one  of  the  dia« 
metral  perforations  in  A  A,  while  the  other,  O,  nearly  coincides  with  the  other  perforation.  If 

'  This  tabic  hai  already  been  given  in  our  Jounial,  yoI.  II.  284. 

Vol.  hi.— August  1799.  E  e  '  10 


906  Jtccount  tfa  new  Pendulum. 

in  this  fituation,  while  the  nut  K  is  but  loofelj  fcrewed  on,  the  bars  B  B  be  pailed  through 
the  perforations  in  the  cylinder,  the  brafs  and  ftcel  pieces,  and  K,  be  then  fcrewed  up,  it 
will  caufe  the  vertical  hole  O,  in  the  one  fteel  piece,  and  L  in  the  other,  to  approach  nearer 
together,  and  carry  the  bars  B  B  along  with  them.  But  this  can  take  place  only  to  a  very 
fmall  extent,  bccaufe  the  bars  will  be  prefled  againft  the  inner  furfaces  of  the  holes  in  the 
brafs  piece  P  P,  which  very  nearly  fit  thofe  bars.  The  ufc  of  the  milled  head  K  is,  there- 
fore, to  difengage  the  weight  A  A  from  the  bars  B  B,  in  which  fituation  the  former  may 
either  be  taken  off,  or  Aided  up  and  down  to  any  dclired  pofition,  where  it  may  immediately 
be  fixed  by  turning  the  nut. 

Fig.  2  fliews  the  whole  pendulum,  which  vibrates  half  feconds,  in  its  full  dimcnfions,  ex- 
cepting as  to  its  length,  which  is  diminiflied  by  a  fra£lure,  reprcfentcd  in  the  middle  of  dK. 
bars,  to  get  it  into  the  plate.     The  fyftem  of  bars  confifts  of  a  crofs-piecc,  G  G,  attached  ta 
another  piece,  H  H,  to  which  the  fprings  of  fufpenfion  are  fixed  as  ufuaL     From  G  G  pro- 
ceed downwards  two  fteel  bars,  which  pafs  through  holes  in  the  brafs  ftage  £  E  (reprefented  alfo 
in  fig,  5),  with  which  they  have  no  connexion,  and  are  firmly  fccured  in  the  ftage,  D  D^ 
which  is  fimilar  to  E  £.     From  the  ftage  £  E  proceed  a  light  pair  of  fteel  bars,  downwards 
through  the  ftage  D  D,  without  connexion  with  this  laft,  and  thence  through  the  cylinder 
A  A,  where  they  appear  at  B  B.     And,  laftly,  from  the  centre  of  the  lower  ftage  D  D,. 
proceeds  upwards  a  bar  of  the  fame  dimenfions,  but  compofed  of  zinc  and  filver,  forming  a 
compound,  which  expands  more  than  twice  as  much  by  heat  as  fteel  does.     This  bar  paflcs. 
through  the  ftage  E  E,  till  it  almoft  reaches  G  G.     It  is  reprcfentcd  by  the  dotted  outline. 
The  ftage  E  E  may  be  Aided  up  and  down,  fo  as  to  vary  its  diftance  from  D  D  ;  but  whcn^ 
required  to  be  fixed,  the  fcrew  pin  F  is  to  be  turned,  which  caufcs  a  piece  to  prefe  againft  the 
central  bar  and  binds  it  faft. 

It  is  fcarccly  neceflary  to  explain  this  aAion.  The  pendulum  A  A  hangs  upon  the  fteel 
bars  B  B,  which  arc  fixed  in  the  ftage  E  E.  This  ftage  is  fupported  by  the  central  rod  or 
pillar  of  zinc  and  filver  which  bears  on  the  ftage  D  D,  and  this  laft  is  fufpended  from  G  G 
by  the  bars  C  C.  If,  therefore,  the  expanfion  of  th«  compound  metal  between  the  ftagcs 
£  and  D  be  equal  to  the  whole  expanfion  of  the  fteel  rods,  and  the  reft  of  the  apparatus 
downwards,  the  centre  of  A  A  will  remain  at  the  fame  diftance  from  the  axi«  of  motion 
whatever  may  be  the  temperature..  But  if  the  effeft  of  the  fteel  be  greateft,  it  will  be  neceC- 
fary  to  raife  the  ftage  £  and  fix  it  higher,  or  in  the  contrary  cafe  it  muft  be  fixed  lower ; 
taking  care  to  preferve  the  due  fituation  of  A  A  with  refpedl  to  I,  by  mcaas  of  its  appara^ 
tus  K. 

This  may  feem  to  be  but  a  rough  method  of  adjufting  for  temperature.  But  when  it  is 
confidered  that  the  whole  daily  diiFerence  in  a  fimple  penduliim  with  a  fteel  rod  amounts  to. 
fix  feconds  at  a  mean  between  fummer  and  winter*,  it  will  be  readily  underftood  that  the 

Philof.  Journal,  i,  58. 

purpofc 


Pendulum^^^Dlfcovcry  of  the  Telefcjfe,  aoj 

purpofe  of  compenfation  for  temperature  will  be  obtained)  as  nearly  as  obfervation  can  indi- 
cate ils  changes,  by  making  the  lengths  of  the  bars  inverfeiy  as  their  expanfions,  as  known 
from  general  eKperiment,  or  from  tables.  Thus,  for  example,  if  brafs  and  ftecl  were  ufed, 
and  their  expanfions  taken  as  113  to  .68,  and  the  whole  length  of  the  brafs  were  10  inches, 
we  may  conclude  that  the  changes  of  temperature  would  not  alter  the  pendulum,  ptovidcd 
the  above  proportions  were  accurately  kept,  namely,  that  the  length  of  the  ftcel  were  16.62 
inches.  But  if  the  proportions  cither  of  expanfion  or  length  (houlJ  be  f)  far  miftaken  or 
neglefted,  as  that  the  brafs  fhould  be  made  one-tenth  of  an  incli  too  fliort,  =  9.9  inches, 
this  piece  would  compenfate  only  16.56  inches  of  fteel,  anJ  confequently  (the  flcel  being 
lengthened  0«i  inch)  there  would  remain  0.16  inch  of  fteel  uncoinpcnfated ;  or  0.016  part 
of  the  whole  pendulum,  which  would  produce  a  difFcrcncc  of  lefs  then  one-tenth  of  a  fccond 
between  the  mean  dally  rates  in  fummer  and  winter. 

The  adjuftment  for  time  is  made  by  a  fcrew  adapted  to  the  fprings  of  fufpenfion,  or  by 
any  other  of  the  ufual  methods ;  of  which  I  do  not  mean  at  prefent  to  confider  the  advan- 
tages and  defefts. 


VI. 
On  the  Epocha  of  the  Difcovery  of  the  Tekfcope^  and  the  Opinion  of  Boyle y  that  Plants  derive 

their  Nourijhment  from  Water  only.     By  Citizen  BoiSSONADE  ♦. 


w. 


E  fometimes  find  In  books  which  are  little  known  and  read,  particulars  of  information 
of  a  very  intercfting  nature.  I  have  found  in  the  Prohabilia  of  the  learned  Wcffeling,  edi- 
tor of  Diodorus  Siculus,  a  chapter  (the  eleventh)  on  the  antiquity  of  aftronomical  telefcopes, 
of  which  I  fend  you  a  tranflation.  The  refcarchcs  it  contains  appear  fufficiently  curious 
to  deferve  to  be  better  known. 

The  aftronomical  telefcope  fi  hy  means  of  which  the  moderns  have  made  difcoveries  in 
the  heavens,  which  efcaped  the  penetration  of  the  ancients,  is,  with  juftice,  placed  among  the 
moft  memorable  inventions.  It  has  often  been  enquired  whether  they  were  known  to  the 
ancient  aftronomers,  and  feveral  writers  have  decided  for  the  afHrmative.  They  ground  their 
opinion  on  an  ancient  drawing  in  the  fcholaftic  hiftory  of  Peter  Comeflor,  in  which  Conrad, 
a  monk  of  the  thirteenth  century,  had  reprefented  aftronomy  J.  "  On  the  right  hand  of  the 
figure,*'  according  to  fother  Mabillon,  who  had  fcen  the  manufcript,  and  mentions  it  in  his 
travels  in  Germany,  there  was  **  a  figure  of  Ptolemy  obferving  the  ftars,  with  a  long  in- 
ftrumcnt  refembling  an  aftronomical  telefcope  with  four  Aiding  tubes  §."     This  conjecture 

*  In  a  letter  to  citizen  Millin,  ^ferted  in  the  Magafin  Encyclop^dique,  v.  466. 

t  I  thus  tranflite  the  words  tubi  oplici.    Note  of  the  writer.— His  objcft  is  to  avoid  the  ambiguity  of  the 
French  word  lunettes;  which  (ign\(ics  fpt^acles  as  well  as  ielefiopes.     I  have  not  the  original  work.     N. 

+  The  Latin  of  Mr.  Wcffeling  is  not  clear  in  this  paffagc,  for  the  underftanding  of  which,  it  is  ncccffary 
to  refer  to  the  work  of  P.  Mabillon,  from  which  he  quotes  only  a  few  lines. 

J  Ope  inftrumenti  longioris  quod  inftar  tubi  optici,  quatuor  du6tus  habenti;;,  concinnatumcft. 

E  e  2  was 


ao8  WhethiP  Tilefcopit  Win  inawn  U  thi  AncienU. 

was  fdrtiEed  by  a  paflhge  of  Ditmar»  bifliop  of  Merfbourgh,  who,  at  the  end  of  bts  fixfift 
book)  (peaking  of  Gerbert,  afterwards  pope  Silvefter  II.  exprefTed  bimfelf  thus:  ^  He  per* 
kStly  knew  the  courfe  of  the  ftars,  and  exceeded-  his  cotemporaries  in  the  variety  of  hii| 
knowledge.  When  driven  from  his  own  country,  he  repaired  to  the  emperor  OthOs  at 
whofe  court  he  remained  a  long  time.  He  conftru£^ed  a  clock  at  Magdebourgh,  and  to  af- 
certain  its  accuracy,  he  oblcrved  with  a  tube  theftar  which  dire£bs  mariners  */'  It  is  thought 
that  Ditmar,  by  the  word  tube,  meant  the  aftronomical  telefcope,.  which,  in  fa£^,  has  a  tube. 
Strabo  alfo  mentions  a  tube  of  this  kind,  if  wc  admit  that  the  text  is  not  in  this  place  cor« 
rupted.  '^  1  he  difc  of  the  fun  acquires  a  more  confiderabic  apparent  magnitude  at  the  riiing 
and  fetting  of  that  luminary  out  at  Tea,  on  account  of  the  quantity  of  vapours  which  rife 
from  the  water,  and  becaufe  the  fight,  refrafted  through  thefe  vapours,  in  thi  fame  manner  at 
through  tubes  t>  receives  the  images  of  a  larger  fize." 

Thcfe  paiTages  appear  to  me  to  be  the  iVrongeft  whiclr  have  been  brought  in  proof  that 
teltfcopcs  were  known  to  the  ancients.     But  it  is  very  furprizing  that  this  knowledge,  if  ic 
exifted,  could  have  been  loft  to  fuch  a  degree,  that  before  the  feventeenth  century  the  moft 
fkilful  and  learned  altronomers  (hould  not  even  CufycQ,  its  exiftence.    Men  have,  at  all  times, 
applied  to  ftudy  the  courfe  and  pofition  of  the  ftars.     No  one  is  ignorant  with  what  ardbui^ 
the  Greeks,^  the  Arabs,  and  the  Latins,  cultivated  aftconomy,  and  how  much  this   ftud^ 
encouraged  by  the  liberality  of  princes,  has  been  conftantly  purfued.     Can  it  be  fuppofed'  tba^ 
the  ancient  obfervers  def^ifed  an  inftrument  fo  ufeful  to  their  labours  ?  I  admit  that  much  of 
the  knowledge  of  antiquity  has  been  loft  by  wars,  by  ravages,  and  a  multiplicity  of  oth^r 
caufes ;  but  if  this  fubjedl  be  attentively  examined,   it  will  be  feen  that  the  information! 
which  has  been  loft,  relates  either  to-  objeds  of  luxury,  or  is  of  fuch  a  nature,  that  greater 
fubfequent  difcoveries  muft  have  caufed  them  to  be  negleded  j  and  &ill  they  are  not  fo  loff 
but  that  fome  trace  of  their  ancient  exiftence  remains.     But  this  is  not  the  cafe  with  telefr- 
copes ;  for  we  have  no  defcription  in  the  writings  of  the  ancients  which  can  agree  with  them. 
Strabo  fpeaks  of  tubes  auAa>v;  but  nothing  leads  us  to  apprehend  that  they  were  ufed  to 
obferve  the  magnitude  and  courfe  of  the  ftars  i,  for  I  cannot  fay  that  I  place  much  depends 
ance   on  the  conjeflure  of  Theodore  Almeloven,  who  thinks  that  Strabo  wrote  vocXcov 
(glaftes).    In  fad,  cryftal^  or  glafs,  is  particularly  endued  with  the  property  mentioned  in  this 
paflage  of  the  geographer.     But  let  us  fuppofe  that  Strabo  wrote  ccvKuy  (tubes))  who  (hall 
aflure  us  that  thefe  tubes  were  provided  with  glafTes?     The  fame  queftibn  may  be. offered 
rcfpefiing  the  painting  of  the  monk  Conrad.     In  h&y  though  it  reprefents  aiKinfitiunent 
«>nliderably  refembling  a  telefcope,  who  can  prove  that  this  inftrument  contained  glafles  likci 
our  telefcopes,  which  without  them  would  be  of  little  utility  ?      I  am  almoft  certain   that 
tuh^  of  Gerbert)  of  which  Ditmar  ^eaks,  had  them  not;  and  in  order  thatlmay  not  be 
ac^itiied  of  deciding  eafily,  I  offer  the  following  proof.    Father  Mahillon,  in  his  Anale^,  has 

•  Confiderata  per  fiftulam  quadam  (lella  ntutarum  ducr. 
•j^  M.V  H  Hv}^i,    Lib.  3.  p^  i3t^. 

pubUih^ 


^  ■ 


On  Tilt/copiS  \^^thi  Nmrljhmint  of  Plants y  Vc.  209 

publiihed  a  letter  of  Gerbert  to  the  monk  Conftantin,  on  the  conftni£tion  of  the  fphere, 
in  which  he  fays,  **  fo  that  there  will  be  feven  perforations)  in  each  of  which  you  will  place 
tubes  (fiftulas)  of  fix  inches.  The  two  extremes,  or  moft  remote,  are  to  be  placed  oppofite 
each  other  in  fuch  a  manner  that  both  may  be  feen  through  as  if  compofing  one 'tube.— * 
"^rhefe  tubes  differ  from  mufical  pipes  (fifiulis  organicis)  in  the  equality  of  their  diameter 
throughout,  for  fear  left  any  obftacle  fhould  impede  the  fight  while  occupied  in  obferving  the 
ccleftial  bodies."  If  thefe  tubes  differed  from  thofe  of  mufical  inftruments  only  in  the  uni- 
formity of  their  bore,  it  is  clear  that  they  had  not  glaffes  ;  confcquently  they  were  not  telcf- 
copes,  but^ioptrx,  and  the  glory  of  the  invention  of  celefcopes  muft  continue  to  belong  to 
the  feventeenth  century. 

I  do  not  confider  the  celebrated  opinion  of  Vanhelmont  and  Boyle  as  equally  new,  who, 
from  well-made  experiments,  thought  that  trees  and  plants  derive  their  principal  nourishment 
from  water.  Thefe  great  oblervers  have  informed  us,  that  if  a  determinate  quantity  of  earth 
be  weighed,  and  if  a  twig  be  planted  in  the  veflel  containing  this  earth,  it  will  be  found 
ievera]  years  afterwards  upon  tranfplanting  the  tree,  that  the  fame  quantity  of  earth  will  re- 
main as  at  firft.  Several  centuries  before  Boyle  and  Vanhelmont,  the  author  of  the  Clemen- 
tine  Recognitions  had  the  fame  idea.  His  words,  book  viii.  chap,  xxvii.  are :  ^  In  order  to 
prove  by  experiment  that  feeds  draw  nothing  from  the  earth,  but  are  entirely  fupported  by 
water,  let  us  fuppofe  that  the  weight  of  one  hundred  talents  of  earth  to  be  put  into  a  very  large 
receptacle,  and  that  the  feeds  of  various  fpecies  of  plants  be  fowed  therein,  and  abundantly 
watered,  for  feveral  years  ^  let  us,  moreover^  fuppofe  that  all  the  feeds  of  wheat,  barley, 
and  other  vegetables,  thus  annually  produced,  to  be  collcwied  until  the  quantity  of  grains  of 
each  (hall  weigh  one  hundred  talents  ;  if  at  this  period  the  roots  be  drawn  out,  there  will  ftill 
be  found  in  the  veflel  from  whence  fo  great  a  produdl  has  been  obtained,  the  original  weight  of 
one  hundred  talents  of  earth.  Whence  can  we  fay  that  this  quantity  of  ieeds  and  trees  was 
formed  ?  Is  it  not  evident  that  it  has  been  produced  from  the  water  ?"  This  paflage  contains 
ezadly  the  fyftem  of  Boyle  and  Vanhelmont.  I  do  not,  however,  think  they  have  borrowed 
it*  Accurate  obfervers  of  nature  are  led  by  their  obfervations  to  very  fimilar  condufions* 
So  true  it  is,  as  Terence  af&rms,  that, 

Ni^um  jam  didum  eft  quod  non  di£him  fit  prius. 

t  may  add'  to  this  chapter  of  Mr.  WeiTeling,  which  has  been  inferted  in  the  Journal  its 
Savans,  for  February,  1679,  the  different  proofs  of  the  exiftence  of  telefcopes  in  the  thirteenth 
century.  It  would  follow  alfo,  from  a  pafiage  of  John,  abbot  of  Beaugency,  that  fpe<Sbcle» 
were  ufed  for  reading  in  the  twelfth  century,  if  the  word  buftula,  ufed  by  this  abbot,  may 
be  tranflated  fpe£bcles.  The  following  is  the  paffage  :  ^  Statim  ut  litterarum  veftrarum  ba« 
^  julam  vidi,  buftulam  arripiens,  non  folum  avide  legi  et  perlcgi  ^."     The  Journal  Encyclo- 

pedique, 

*  ThitpalTage  hat  very  often  been  quoted  in  favour  of  the  invention  of  fpefVacIes  in  the  thirteenth  cen- 
tury.   It  is  thought,  nevf  rthelefs,  with  much  probability,  that  the  word  bui^ula  comes  from  the  word 

buxus 


210  On  the  Strength  and  Prcperius  of 

pedique,  for  M:iy,  1766,  in  whldi  there  is  a  long  article  on  the  fubjeA,  gives  his  fenfe  to 
the  wordy  and  adds,  that  the  principles,  according  to  which  fpe^cks  arc  fabricated,  are 
found  in  Euchd  and  the  ancient  geometers. 


VII. 

Ohfcrvatioyts  on  the  Proportio'fi  of  real  Acid  in  the  three  ancient  known  mineral  Acids y  and  on 
the  liigndieKts  }',:v:n'i:us  neutral  Salts  and  other  Compounds.''^  By  RiCHARD  JilRWAN^ 
Esz:  LL.D.  F.R.S.  and  A/.R.LA. 

J.  HE  fundamental  experiments  on  which  the  proportion  of  real  acid  in  the  three  mineral 
acids  anciently  known,  and  alfo  the  proportion  of  ingredients  in  many  neutral  falts,  were 
determined,  are  fet  fordi  in  a  paper  of  Mr.  Kirwan,  in  the  1  Vth  vol.  of  the  Tranfaftions  of 
the  Irifli  Academy.  That  paper  contains  tables  of  tlie  quantity  of  ftaniard  acid  exifting  in  100 
parts  of  each  of  the  acid  liquors,  of  given  fpecific  gravities,  and  Silfo  in  each  of  the  neutral  falts 
therein  mentioned,  according  to  a  method  which  Mr.  Kirwan  has  fince  difcovered  to  be  very 
inconvenient,  becaufe  fomc  of  thcfc  neutral  falts  contain  an  acid  ftill  ftronger  than  the  af- 
fumed  ftandard.  It  Is  there  alfo  noticed,  that  the  ftrongeft  vitriolic  acid  now  known  exifts  in 
vitriolated  tartarin^  the  ftrongeft  nitrous  acid  in  nitrated  fodt^  and  the  ftrongcft  muriatic  acid, 
in  muriated  tartarin.  Acids  of  fuch  ftrength  he  has,  therefore,  denominated  realy  as  either 
containing  no  water,  or  containing  only  as  much  as  is  neceflary  to  their  cflential  compofttion) 
as  far  as  is  at  prcfent  known.  The  method  of  transforming  the  ex^r^t[\onJlandard  mto  that 
of  real^  is  given  in  the  fame  paper  at  p.  67,  and  by  it  he  has  formed  the  table  here  preftnted. 
This  latter  expreflion  he  therefore  employs  in  every  cafe  inftead  of  that  of  Jlandard^  together 
with  the  fubftitution  of  a  more  commodious  expre/fion  of  the  ftrength  of  acids.  Another 
obje£t  of  his  prefent  communication  is,  to  exhibit  an  llluftration  or  amendment  of  feveral  of 
the  determinations  contained  in  his  laft,  which,  being  for  the  moft  part  fingle,  required  con- 
firmation, by  fhewing  their  agreement  with  the  experiments  of  feveral  of  the  moft  eminent 
chemifts,  made  fince  that  publication,  that  is,  fince  the  year  1791,  with  a  few  made  nearly 
at  the  fame  time.  In  his  former  paper  he  compared  his  refults  with  thofc  of  Bergman  and 
Wenzel,  they  being  almoft  the  only  perfons  who  had  made  this  fubje^l  the  principal  objcft  of 
their  enquiry,  and  had  purfued  it  to  a  confiderable  extent,  in  each  particular  inftance  he 
traced  the  reafon  of  the  difference  of  their  refults  from  his  own,  when  it  was  fuch  as  to  deferve 
notice :  he  does  not,  therefore,  repeat  what  was  there  obferved ;  but  cannOt  avoid  again  men- 

buxus  (box),  and  denotes  the  little  box  in  which  the  letter  was  contained.  According  to  this  interpretation, 
the  above  may  be  thus  tranflatcd.  "  As  foon  as  I  faw  the  bearer  of  your  letters,  I  fcized  the  fmill  box 
wJiich  contained  ihcm,  and  frequently  read  them  over  with  avidity  j"  and  not  that  I  fnatchcd  up  my  fpcc- 
tacles.    Note  of  citizen  Millin. 

•  Abridged  from  an  extcnfive  paper,  which  will  hereafter  appear  in  tbe  Traxifa£^ions  of  the  Royal  IriHi 
Academy.    J  was  favourcc',  by  the  author,  with  this  paper,  entitled.  Additional  Oh/ervations,  Sec. 

tioning 


the  thru  ancient  Mfneral  Act  Is.  an 

tioning  one  general  fource  of  error  attending  the  mode  of  inveftigation  adopted  by  both,  and 
yet  noticed  by  neither,  namely,  the  lofs  that  many  neutral  falts  undergo  during  evaporation ; 
alofs,  whofe  difcovery  is  of  confiderabic  importance,  not  only  to  the  prefcnt  enquiry,  but  alfo 
to  the  conduft  of  feveral  manufaclurcs,  particularly  to  that  of  faltpctre,  and  hence  noticed  by 
Mr.  Lavoificr,  15  4n.  Chem.  254. 

Other  remarks  and  obfcrvations  refp^fting  the  experiments  of  Bergman,  Wcnzel,  and 
other  cbemifts,  form' a  very  eflential  and  valuable  part  of  the  paper;  but  the  indifpenfablc 
attention  to  brevity,  which  the  nature  and  objeft  of  a  periodical  work  demands,  will  oblige  mc 
to  confine  this  abftradl  to  the  immediate  ftru<Surc  and  ufe  of  the  tables. 

When  alkalies  or  earths,  combined  with  fixed  air,  are  diflblved  in  acids,  though  far  the 
greater  part  of  the  fixed  air  is  expelled  during  the  folution,  yet  fomc  portion  of  it  is  often 
retained,  and  may,  in  fome  degree,  alter  the  fp.  grav.  of  the  folution ;  tliis  circumftance  was  not 
recoReded  by  Mr.  Kirwan  till  lately ;  it  was  firft  noticed  by  Mr.  Cavcndifli,  Phil.  Tranf- 
1766,  p.  172,  and  afterwards  by  Bergman,  in  his  notes  on  SchefR-T,  §  5ij  but  more  explicitly 
by  Scheele,  Chy.  An.  1786,  p.  13,  and  by  Butini  on  Magnefia,  p.  149.  As  to  the  ufe  rc- 
fulting  from  refcarchcs  of  this  nature,  he  remarks  that  it  would  be  fuperfluous  to  attempt  to 
prove  it  at  this  day ;  as  the  recourfe  which  the  mofl  eminent  analyils  have  been  obliged  to 
have  to  it  in  particular  inflances,  fufficicntly  evinces  it.  ^^  Inquiries  of  this  kind  (fays  Mr. 
•*  Fourcroy)  are  more  dif&cult  and  delicate  than  tliofe  which  have  hitherto  been  made  oii 
*•  ialts;  whatever  requires  a  precife  knowledge  of  quantities  and  proportions,  prefents  difficul- 
**  ties  fo  great  as  often  to  appear  infurmountable,  yet  without  this  knowledge  no  progrefs 
"  can  now  be  made  in  chemiflry,**  10  An.  Chy.  325  \  and  according  to  Bergman,  *'  Ufus 
^  cognits  proportionis  principiorum  ingredientium  egregius  efl  et  multifarius."  i  Bergm. 
137*  chap.  I.  §  I. 

!!)€  Experiments  made  for  afcertalnlng  the  Changes  of  Denftty  in  the  Acids  by  Oiange  of  Tem^ 

perature^  were  as  follow  : 

Vitriolic  acid  1,8360  at  temperature  60^,  becomes  1,8292  at  70°;.. ..1,8317  at  65^;.... 
1,8382  at  55** ;....!, 8403  at  50°;... .and  1,8403  at  49^^ — Hence  we  fee  that  vitriolic  acid, 
whofe  denfity  at  60°,  is  1,8360,  lofes  by  ajcending  and  gains  by  defcending  o,Ooo6S  for 
every  degree  of  temperature  between  60^  and  70S  and  0,00043  nearly  by  each  degree  be- 
tween 60°  and  49^. 

Again,  vitriolic  acid  1,7005  at  60^,  becomes  1,6969  at  70^  ;....  1,6983  at  65*^;....  1,7037 
at  55^  5  and  1,7062  at  50^. — Hence  vitriolic  acid,  which  at  60^  is  1.7005,  gains  or  lofcs 
0,00036  nearly  for  every  degree  between  60^  and  70^,  and  c,coo5i  by  every  degree  between 
60^  and  50^. 

Laf^ly,  vitriolic  acid  1,3888  at  60^,  becomes  1.3845  at  70^  ;....  1,3866  at  65°;.. ..1,3898 
5it55^;   and   1,3926  at  40^. — Hence  vitriolic  acid,  which  at  60^  13  i>3888,  gains  or  lofcs 

o,ooj4x 


■■!■' 


212  On  the  Expanfton  cfJctds  hj  Hiot.  % 

0,00043  nearly  by  every  degree  between  60*^  ahd  70^,  and  0,00034  nearly  by  every  degree 
between  49^  and  60*^ ;  between  49*^  and  50**  no  difference  was  perceived. 

The  Alterations  (/  Denfity  from  Difference  of  Temperature  In  Nitrous  Acid^  were  as  follow  : 

m 

Nitrous  acid,  which  was  1)4279  at  60^,  became  1,4178  at  70^  ;....i,422{  at  65^;....  1,4 304 
at  55®  ;....  1,4336  at  50*^ ;  and  i|43S7  at  45^. — Hence  nitrous  acid,  which  at  60?  is  1942799 
gains  or  lofes  o,opioi  nearly  by  every  degree  between  60®  and  70^ ;   and  0,00052  by  every 
•degree  between  45^  and  60^. 

It  was  formerly  found  by  Mr.  Kirwan,  that  the  ftrongeft  fpirit  of  nitre  is  moft  expanded 
by  heat,  or  contracted  by  cold.  Alfo,  that  nitrous  acid,  whofe  fp.  grav.  at  34^  Viras  1,47501 
was  expanded  by  heat,  as  follows :  viz.  1,4750  at  34^  became  1,4653  at  49^ »  whence  it 
gains  or  lofcs  0,0097  by  15")  between  34^  and  49^  incluiively. 

Again,  that  colourlefs  nitrous  acid,  whofe  fp.  grav.  was  1^.650  at  30^,  became  1,4587  at 
46^,  and  1,4302  at  86^. — Whence,  by  the  firft  16S  from  30^  to  46^,  it  gained  0,0063,  and 
by  40^,  that  is^  from  46  to  86^,  it  gained  0,0285. 

Again,  nitrous  acid,  whofe  denfity  was  1,2363  at  60^9  became  1,2320  at  70^  ;••••!  12342 
at^65%..  I22384  at' 55*^5... .1,2406  at  50^;  and  1,2417  at  45**.— Whence  nitrous  acid, 
which  at  60^  is  i>2363,  gains  or  lofes  by  every  degree  between  6o^  and  70^  0,00043,  and 
0,00036  by  eviery  degree  betwen  60^  and  45^ ;  and  we  may  afiume  0,^005  as  the  variation 
incident  to  every  degree  between  60®  and  70^  in  nitrous  acid,  whofe  denfity  at  60^  is  be-^ 
tween  1,3  and  1,4,  and  0,0004  for  the  variation  between  44^  and  60^. 

Of  Marine  Acid. — It  was  formerly  found  that  this  acid  of  the  denfity  1,196  at  33^  be- 
came of  die  denfity  1,1820  at  66^  ;  the  alterations  of  acids  of  lower  fp.  grav.  were  not  exa« 
minej ;  but  it  was  found  that  in  general  its  dilaubility  \s  greater  than  that  ^i  nitrous  acid  of 
the  fame  denfity. 


Table 


(    »'3    ) 
Tablb  of  the  Quantity  of  Real  Mid,  i«  loo  Parts  of  VitrioUe,  NitrmstJini 
Marine  /ai  Ltquon  of  different  Denfities,  at  the  Temperature  o/"6o°. ' 


In  ^.r;J/ 

^.,J^>f 

lifisrait  Denfitiei. 

ht  Ajf.ow 

^.■V,/ofd;flercnl  DcntuicB, 

hi   .\Uri-< 

./.,„  cl- 

at  thcTemiieratur.;  oI*6o". 

atlh 

cTenil)e«tuteof6oO. 

iheT.-mp.oflio'', 

R»I 

IQO  P».I> 

Rtil 

■OOP,,,, 

!t«l 

100  P*«) 

BcI 

Rnl 

er.  Gnvny 

Afd. 

Sj..  Cravitj, 

Acid 

Sp.  o,„l,, 

Acid 

Sp.  Cra.liy 

Ada, 

Sp.  ChvIii- 

Acd. 

2,0000 

T4666 

44,64 

■.iS43 

;3!4 

1,3364 

+1.51 

.,■96 

25,28 

i.ySs9 

1,4427 

43,7; 

■.S»5S 

6986 

1,3  3' S 

41,18 

1.191 

14,76 

1.9719 

S7,jia 

.,4189 

42,b6-f 

1,5.83 

■.9,1" 

1. 3*64 

+0,44 

1,187 

!4.V; 

'■y.^79 

H6/)i 

1,4099 

41,96 

68,39 

1,3112 

i9'T^ 

1,183 

^3,73 

i.94jy 

S5..71 

1,4010 

+  1,07 

'■4957 

67.65 

1,3160 

3S,97 

i,'79 

23,13 

84,Sa 

I. .5  875 

40,18 

,,4»44 

66,92 

1,3.08 

ia,3+ 

'i'75 

22,70 

3j^93 

i,3r68» 

59.1H 

.,473' 

66.18 

1,3056 

37.50 

1,171 

J  .yo+S 

83,044 

'../'6, 

3d,J9 

',47'9 

65.4s 

1,300^ 

3^77 

.,,67 

=  1.67 

i,8yi  + 

82.14 

1,^5  [id 

37.50 

1,4707 

64.71 

1,2,)  11 

36.03 

1,163 

s,.i5 

i,87H7 

3 1, 35 

',J47.i 

36,60 

1,469; 

63.&S  + 

I  33l3 

35-30  + 

',iS9 

20,6+ 

1.8660 

30,36 

i.j.j6o 

35.ri 

1,46^3 

63,24 

■.=79S 

34-56 

i.'s; 

20, 1  a 

i,8j+2 

79.45 
73.57 

1.3254 
'.3149 

34,Si 
35.93 

1,467' 
1,4640 

62,5' 

6'.77 

1.2779 
1,2687 

1,151 
1.147 

i960 

1.S434 

33.09 

19,09 

,,8,jo6 

77,63 

1,3101 

5  3.0J 

■  ,4611 

61,03 

i,a:;86 

J2..15 

1,1414 

't-". 

i,Si88 

76.79+ 

1.5056 

3=  14 

..,S8z 

60,30 

1,2500 

J  1.62 

1. 13  96 

18.06 

,,8070 

7589 

1,2951 

31.25 

',4553 

5').  5' 

1,1464 

50, «8 

1,1358 

'-■54 

1.79J9 

.''fS 

30.35 

'■4i'4 

S»,»3 

1,2419 

iO.IJ 

I'liSz 

17.03 

1,7849 

74,^1 

29,46 

'.447' 

56,09 

i.2.')74 

19,41 

i6,s< 

7.;.=2 

'i.I'm3 

^a.57 

'44=' 

57.36 

1,2:91 

i3.63 

M244 

■S.C9 

i!7''jy 

r2,ji 

i,25!5y 

27,68  + 

'4i73 

50,6a 

1,2109 

^7.94 

15.43 

1.75 'y 

7'.4.J 

1,2510 

16,78 

'43=4 

55,89 

17.21  + 

i,ri63 

14,96 

1.7416 

7° -54  + 

i.^4>5 

25,89 

',M7S 

55.IS 

i,*i5» 

26,47 

14,44 

>.7i'2 

'59.'54 

1.2J20 

25.— 

J:4a22 

i4'  =  + 

1,2033 

2  5  74+ 

1,10:8 
1,1036 

'.V)J 

■  1,7208 

6S,75 

24,  JO 

1,4' 71 

53.63 

;5,DO 

13.41 

i.7'04 

67,86 

1,2101 

23-1' 

1.4,20 

S''.S4 

'SM 

24,26 

1,0984 

13,9a 

1,7000 

66.g6 

i,20og 

21.32 

',4069 

5 '.2 1 

23.53 

1,0943 

12,38 

i,68gp 

66,07 

I,.ql8 

21.43-f- 

1,4018 

S'.4f 

I'.Xl 

13,79 

1,0910 

■  i.Gd 

1,6800 

65,18 

1.1836 

20.53 

i-39rs 

50,74 

1,1779 

13  .06 

1,0868 

".35 

1,67°" 

64.2S 

■  ,1746 

19,64 

'.3,,a5 

50.00 

1,1704 

31.32 

1,0826 

io8,j 

i,6ftoi 

153.39 

1,1678 

■a.75 

4'>.27 

J  i6j9 

20,i;9 

1,0784 

io,3» 

1,6503 

6;, 50 

.,i6h 

■  7,85 

\':W'< 

4'- 5  3 

1,158. 

19.85 

1,0743 

9,80 
6,35 

1,6407 

e.,'^! 

','i3i 

16,96 

'•3777 

47,^0 

1,15/4 

19.12 

i,o6jO 

J,6ji3 

1,1598 

16,07 

1.3-ai 

.7,06 

1,1421  |l8„^S 

i,'-:J4S 

5,1 6 

1,6217 

19.82 

'.1309 

15.J8  + 

.,367' 

46.33 

M^i9    '7.G;  + 

1,0169 

=,S8 

1,6. a> 

s^m 

l,I2o8 

14.28 

','621 

45.5'J 

i,i;.l!4   116,91 

1,6017 

Si'^S 

1,1129 

■3.39 

',357' 

44.864- 

i,i24>     '6,17 

1.5931 

1,10,1 

'2.50 

'.352' 

41.12 

1,1165     15,44 

'.5^40 

55..i6  + 

54-46 

11.60 

1,346s 
'.34'7 

4i.lS 
4=,6S 

1,1111     14,70 

f.T040      1^27 

.,574K 

"S 

t,s656 

TJicNu 

mbcraabovcUie  LiiM-sUrawii 

1.5564 

5i--.>7 

»,0i  + 

aciila  tL= 

Tiil.lts  iif  Mlr;i.,:ii-   ailrl  iii- 

1.5+73 

52,68 

■-37-5 

8,03 

trous  Aci 

-   were   fouinl   1';-   l-'j.cri. 

1.5385 

5'.7B 

i,o066 

7."4 

mentsi   l! 

jI'.^  under  llie  Liii'f:  unlj-  I.;, 

1.5393 

5°.69 

i,c6io 

>>■'! 

Analogy. 

l._^103' 
1.5113 

1,0491 

4.f6 

49.1  i  + 

The  A 

■.n;t;'  .if  vllri.ilii:  .Ai'..l    t.. 

J.J013 

4^=| 

r,o4So 

'i' 

Water  de 

reai.-i   ir.  -the    Hilio  ul"  tht 

'.4qJ3 

47..^  = 

1.0396 

2,6, 

Square  oft 

hcUiuMilyiii  W..t!T!.niln'i 

,,4844 

46.43 

'.0343 

'.78 

to  it.      SI 

Anil,  Cav.   Ii^6a:i()  lyT, 

; 

'■4755 

45  S3 

MA  1« 
other  :-..;> 

Mi.  K.  think.  ;i.iw!it.',«li 
;j:..%s;   iti«*hcn..flH  Alii- 

' 

"  *  Ihc 

ty  was  1,37+1  iu 

the  funncr 

Tabk. 

tiiij'  ihtt 

s  c-jnmo 

.ly  givtn. 

Svlf.  The  Itindard  Qiiantiiiei  of  ykriflic  Atii  <>'  :v  reduced  to  ^  Wby  mulliplTing 
of  itic  Kt'tiii,  by  mu'.tipljuig  ihcm  into  0,7] ^  ■,  aa.J  iLl-  M,ii:ni!  ov  multiplying  tBCia: 
ReaCink  mentioned  in  the  Auihor'i  laft  P^pci. 

Vol.  III.— August  IJ99.  F  f 


them  intOQi^^ig; 
into  9,j  16,  tor  the 


214 


Saline  Compounds. 


Table  II. — Quantity  of  Real  Acid  taken  up  by  mere  Alkalies  and  Earths. 


lOo  Parts. 

Vitriolic. 

Nitrous. 

Marine. 

Fixed  air. 

Tartarin          -         -           - 

82.48 

84,96 

0,3 

xo;  aliiioll 

Socl-i         .         .         -        . 

127,68 

»357' 

73>4i 

66  8 

Vol-alkali 

383,8 

247,82 

171 

Variable 

Barytes         -           -           - 

.fjO 

56 

31,8 

282 

Strontiau           -         -        - 

72,4* 

85,56 

46 

43,s 

Lime            .           -           - 

»43 

'79»5 

84,4^8 

81,81 

Magncfia         -         -         - 

172,64 

210 

iii>3S 

aoo  Fourcroy 

Argill 

150,9 

335  nearly,  Bergman n 

Table  III. —  Of  the  Quantify  of  Alkalies  and  Earths  taken  up  by  100   Parts  of  Real  Vitriolic^ 

Nitrous,  Murialic,  and  Carbonic  Acids,  faturatcd. 


100  Parts. 


Vitriolic 
Nitrous 
Muriatic 
Carbonic 


Fartarin. 

Soda. 

Vol-alkali. 

Bar\*tcs. 

• 

Strontian. 

Lime. 

Magnefia. 

X2X,48 

>>7>7 
I77i6 

9Si* 

78,32 

73^43 
136,2 
149,6 

26,05 

40,3'; 
58.48 

200 
178,12 
3*4,46 
3S4.5 

138. 
116,86 
2 16,2  X 

231,+ 

7c. 
55.7 

118,3 
122, 

57»9» 
47»6+ 
89,8 

Table  IV» — Quantity  of  Neutral  Salts  afforded  by  ;oo  Parts  of  the  abovtnamed  Acids  wien 

faturated  with  the  abovenavied  Bafes, 


100  Parts 

rartarin. 

Vitriolic 

221,48 

Nitrous 

W7,22 

Marine 

277,6 

Carbonic 

t 

Soda. 


C    425  chnltalN  1 
\  178,5  dcuccd      j 


188 

257>a 


("69,35  cryflalH   7 
(     150  deficc**     J 


Vol- 

Alkali. 


182,94 
'75*44 

23.3>9 


Barvtes. 


I 


300 


|487.4chyftall«i 
(454,5  defies* 

4S4'5 


} 


Strontian. 


238 


540  cryfiall^ 
313,5  deliccd 

331.7 


Lime. 


white  heat 
o 


C  i7oinawhi 

(  198  at  170^ 

1 74  well  dried, 

that  is,  in  air 

238  in  a  red  heat 


222,25 


Magnefia. 


340  cryftallized 
158  deficcated 


286,2  well  dried 


200 


Table  V. — Quantity  of  Neutral  Salt  afforded  by  lOo  Parts  of  different  B 

with  the  Vitriolic,  Nitrous,  Marine,  or  Carbonic  Acid. 


Bafes  when  combined 


100  Parts. 


Tartarin 

5o(fa 

Vol-alkali 

Bar}'tc3 

Strontian 

Lime 
i^Iagnella 


Vitriolic, 


I 


182,48 

r  541,1  crj-ftallized   1 
I  22,74   dcliccatcd    J 

7oa,94 

150 

172,4' 


Nitrous. 


193  + 
246,42 

435 


Marine. 


I. 


Carbonic  Acids. 


.7 


r  588,23  cryftallized  1 
1 272,63  defiocated    j 


312  dried  at  80° 
280  fully  deficcatcd 


J 


1 56  J 
188,74 

400 
f  155,  ?6cn'ftalll2ed " 

[  142,8  dcficcati'd 

[250  cryltalli/.cd 

[145  dcliccatcd         J 

206  in  a  red  heat 


J3ai,8  gently  but  fcnfi- 
bly  dried 


244 

I  463,3  cryftallizcd 
\  167  dcficcated 

382 

143,16 

182 


\ 


40P 


Table 


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4l6  Submarine  ForeJI  on  the  tajl  Coafl  ofSngland. 

VIII. 

On  a  fulmar Ine  Forejl  07t  the  enji  Coaji  of  England  *.     By  JosEPH  CORREA  DE  SeRSA 

LL,D.  F,R,S.  and  J.S. 


I 


N  geology,  more  perhaps  than  in  any  other  branch  of  natural  hiftory,  there/Cxifts  a  necef- 
fity  of  ftriftly  feparating  the  ftifts  obfervcd  from  the  ideas,  which,  in  order  to  explain  them, 
may  occur  to  the  mind  of  the  obfcrver.  In  the  prcfent  ftate  of  this  fcience,  every  well  af- 
certained  faft  increafes  our  ftill  narrow  ftoclc  of  real  knowledge ;  when,  on  the  contrary,  the 
rcafonings  we  are  enabled  to  make  arc,  at  beft,  but  ingenious  gueJDTcs,  which  too  often  bias 
and  miflead  the  judgment.  I  fliall,  therefore,  endeavour  in  this  paper,  to  give,  firft,  a  mere 
defcription  of  the  objeft  unmixed  with  any  fyftematical  ideas,  and  (hall  afterwards  offer  fuch 
conjeflures  on  its  caufe  as  fecm  to  me  to  be  fairly  grounded  on  obfervation. 

It  was  a  common  report  in  Lincolnftiire,  that  a  large  extent  of  iflets  of  n^oor,  fituated 
along  its  coaft,  and  vifible  only  in  the  lowcft  ebbs  of  the  year,  was  chiefly  compofed  of 
decayed  trees.  Thefe  iflets  are  marked  in  Mitchell's  chart  of  that  coaft,  by  the  name  of 
clay  huts ;  and  the  village  of  Huttoft,  oppofite  to  which  they  principally  lie,  fcems  to  have 
derived  its  name  from  them.  In  the  month  of  September,  1796,  I  went  to  Sutton,  on  the 
coaft  of  Lincolnftiire,  in  the  company  of  the  right  honourable  prefident  of  this  fociety,  in 
order  to  examine  their  extent  and  nature.  The  19th  of  the  month,  being  the  firft  day  after 
the  equinoftial  full  moon,  when  the  loweft  ebbs  were  to  be  expefled,  we  went  in  a  boat  at 
half-paft  12  at  noon,  and  foon  after  fet  foot  upon  one  of  the  largeft  iflets  then  appearing. 
Its  expofed  furface  was  about  thirty  yards  long,  and  twenty-five  wide,  when  the  tide  was; at 
the  loweft.  A  great  number  of  fimilar  iflets  were  vifible  round  us,  chiefly  to  the  eaftward 
and  fouthward  ;  and  the  fiftiermen,  whofc  authority  on  this  point  is  very  competent,  fay  that 
fimilar  moors  are  to  be  found  along  the  whole  coaft,  from  Skegnefs  to  Grimn>y,  particularly 
off  Addelthorpe  and  Mablethorpe.  The  channels  dividing  the  iflets  were,  at  the  time  we 
£iw  them,  wide  and  of  various  depths ;  the  iflets  themfclves  ranging  generally  from  eaft  to 
weft  in  their  largeft  dimenfion. 

Wc  vifited  them  again  in  the  ebbs  of  the  20th  and  21ft  ;  and  though  it  generally  did  not 
ebb  fo  far  as  we  expcdled,  we  could,  notwithftanding,  afcertain  that  they  confifted  almoft 
entirely  of  roots,  trunks,  branches,  and  leaves  of  trees,  and  ftirubs,  intermixed  with  fome 
leaves  of  aquatic  plants.  The  remains  of  fome  of  thefe  trees  were  ftill  ftanding  on  their 
roots ;  while  the  trunks  of  the  greater  part  lay  fcattered  on  the  ground,  in  every  poffible 
dire£lion.  The  bark  of  the  trees  and  roots  appeared  generally  as  fre(h  as  when  they  were 
growing)  in  that  of  the  branches  particularly,  of  which  a  great  quantity  was  found ;  even 
the  thin  filvery  membranes  of  the  outer  ikin  were  difcernible.  Tbe  timber  of  all  kinds,  on 
the  contrary,  was  decompofed  and  foft  in  the  greatcft  part  of  the  trees  >  in  fome,  however^ 

m 

*  Philof.  Tranfailions,  1799. 

it 


Buhtnarifie  Forefl  on  the  eujl  Coqfl  of  England.  art  7 

it  was  firm,  efpecially  in  the  roots*    The  people  of  the  country  have  often  found  among 
them  very  found  pieces  of  timber,  fit  to  be  employed  for  fevcral  economical  purpofes. 

The  forts  of  wood  which  are  ftiil  diftinguiftiablc,  are  birch,  fir,  and  oak.  Other  woods 
evidently  exift  in  thefe  ifletS)  of  fome  of  which  we  found  the  leaves  in  the  foil ;  but  our 
prefent  knowledge  of  the  comparative  anatomy  of  timbers  is  not  fo  far  advanced  as  to  afford 
us  the  means  of  pronouncing  with  confidence  rcfpcfting  their  fpecies.  In  general,*  the 
trunks,  branches,  and  roots,  of  the  decayed  trees,  were  confiderably  flattened ;  which  is  a 
phenomenon  obfcrvcd  in  the  furtarbrand^  or  foflii  wood  of  Iceland,  and  which  Scheuchzer 
remarked  alfo  in  the  fo/fil  wood  found  in  the  neighbourhood  of  the  lake  of  Thun,  in  Swit- 
zerland. 

The  foil  to  which  the  trees  are  affixed,  and  in  which  they  grew,  is  a  foft  greafy  clay  ;  but 
for  many  inches  above  its  furface,  the  foil  is  entirely  compofed  of  rotten  leaves,  fcarcely 
diftinguifhable  to  the  eye ;  many  of  which  may  be  feparated,  by  putting  the  foil  in  water, 
and  dexteroufly  and  patiently  ufing  a  fpatula,  or  blunt  knife.  By  this  method  I  obtained 
fome  pcrfedl  leaves  of  ilUx  aquifoUumy  which  are  now  in  the  herbarium  of  the  right  honour- 
able fir  Jofeph  Banks,  and  fome  other  leaves,  which,  though  lefs  perfeft,  feem  to  belong  to 
fome  fpecies  of  willow.  In  this  flratum  of  rotten  leaves,  we  could  alfo  diftinguifh  feverat 
roots  of  arundo  phragmites, 

Thefe  iflets,  according  to  the  mod  accurate  information,  extend  at  leafl  twelve  miles  in 
length,  and  about  a  mile  in  breadth,  oppofite  to  Sutton  fhore.  The  water  without  them^ 
towards  the  fea,  generally  deepens  fuddenly,  fo*  as  to  form  a  fteep  bank.  The  channels 
between  the  feveral  iflets,  when  the  iflets  are  dry  in  the  loweft  ebbs  of  the  year,  are  from  four 
to  twelve  feet  deep  ^  their  bottoms  are  clay,  or  fand,  and  their  diredtion  is  generally  from  eaft 
to  wefl. 

A  well,  dug  at  Sutton  by  Jofliua  Searby,  &ows  that  a  moor  of  the  fame  nature  is  found 
under  ground  in  that  part  of  the  country,  at  the  depth  of  fixteen  feet;  coniequentIy»  very 
nearly  on  the  fame  level  with  that  which  conflitutes  the  iflets.  The  difpofition  of  the  ftrata 
was  found  to  be  as  follows : 

Clay,  -  -  -  .  -••  -  •  16  feet 

Moor,  fimilar  to  that  of  the  iflets,  from  »  -  -  -         3  to  4  do. 

Soft  moor,  like  the  fcowerings  of  a  ditch  bottom^  mixed  with  (hells  and  filt»  20  do. 

Marly  clay,  -  ...  -  -  i  do. 

Chalky  rock,  from     -  -  •  -  -^«  -  1  to  2  do. 

Clay,  ----...,.  ji  yards. 

Gravel  and  water.     The  water  has  a  chalybeate  tafl^ 

In  order  to  afcertain  the  courfe  of  this  fubterraneous  ftratum  of  decayed  vegetables,  fir  J. 
Banks  dlreded  a  boring  to  be  made  in  the  fields  belonging  to  the  Royal  Society  in  the  parifh 
of  Mablethorpe.  Moor,  of  a  fimilar  nature  to  that  of  Searby's  well,  and  of  the  iflets,  was 
found  very  nearly  on  the  fame  level,  about  four  feet  thick>  and  under  it  a  foft  clay. 

The 


2i8  Snbmarine  Forefl  on  the  eaft  Coaji  of  Englofid* 

The  whole  apppearance  of  the  rotten  vegetables  we  obferved,  perfeftly  refembles,  accord- 
ing to  the  remark  of  fir  J.  Banks,  the  moor  which  in  Blankeney  fen,  and  in  other  parts  of 
,  the  eaft  fen,  in  Lincolnfhire,  is  thrown  up  in  the  making  of  banks ;  barks,  like  thofe  of  the 
birch  tree,  being  there  alfo  abundantly  found.  This  moor  extends  over  all  the  Lincolnfliire 
fens,  and  has  been  traced  as  far  as  Peterborough,  more  than  fixty  miles  to  the  fouth  of  Sutton, 
On  the  north  fide,  the  moory  iflets,  according  to  the  fifhermen,  extend  as  far  as  Grimfby," 
fituated  on  the  fouth  fide  of  the  mouth  of  the  Humber  ;  and  it  is  a  remarkable  circumftance, 
that,  in  the  large  tracts  of  low  lands  which  lie  on  the  fouth  banks  of  that  river,  a  little  above 
its  mouth,  there  is  a  fubterrancous  ftratum  of  decayed  trees  and  (hrubs,  exaftly  like  thofe 
we  obferved  at  Sutton  ;  particularly  at  Axholme  iflc,  a  tradt  of  ten  miles  in  length  by  five  in 
breadth ;  and  at  Hatfield  Chafe,  which  comprehends  one  hundred  and  eighty  thoufand  acres. 
J.  Dugdale  *  had  long  ago  made  this  obfcrvation  in  the  iirft  of  thefc  places  ;  and  de  la  Pryme  t» 
in  the  fccond.  The  roots  are  there,  likewife,  (landing  in  the  places  where  they  grew;  the 
trunks  lie  proftrate.  The  woods  are  of  the  fame  fpecies  as  at  Sutton.  Roots  of  aquatic 
plants,  and  reeds,  are  likewife  mixed  with  them;  and  they  are  covered  by  a  ftratum  of  fome 
vard^  of  foil,  the  thicknefs  of  which,  though  not  afcertained  with  exaftnefs  by  the  above- 
mentioned  obfervers,  we  may  eafily  conceive  to  correfpond  with  that  which  covers  the  ftratum 
of  decayed  wood  at  Sutton,  by  the  circumftance  of  the  roots  being  (according  to  Mr,  Ri- 
chardfon's  obfervations  %)  only  vifible  when  the  water  is  low,  where  a  channel  was  cut,  and 
has  left  them  uncovered. 
-J  Little  doubt  can  be  entertained  of  the  moory  iflets  of  Sutton  being  a  part  of  this  extenfive 

and  fubterrancous  ftratum,  which,  by  fome  inroad  of  the  fea,  has  been  there  ftripped  of  its 
covering  of  foil.  The  identity  of  the  levels  -,  that  of  the  fpecies  of  trees  ;  the  roots  of  thefe 
affixed  in  both  to  the  foil  where  they  grew  ;  and,  above  all,  the  flattened  fliape  of  the  trunkSi 
branches,  and  roots  found  in  the  iflets  (which  can  ©nly  be  accounted  for  by  the  heavy  pref- 
fwe  of  a  fuperinduced  ftratum),  are  fuflicient  reafons  for  this  opinion. 

Such  a  wide-fpread  aflfemblage  of  vegetable  ruins,  lying  almoft  in  the  fame  level,  and  that 
level  generally  under  the  common  mark  of  low  water,  muft  naturally  ftrike  the  obferver,  and 
give  birth  to  the  following  queftions  : 

1.  What  is  the  epoch  of  this  deftruflion  ? 

2.  By  what  agency  was  it  eflFefted  ? 

In  anfwer  to  thefe  queftions,  I  will  venture  to  fubmit  the  following  rcfle<£tions. 

The  foflil  remains  of  vegetables,  hitherto  dug  tip  in  fo  many  parts  of  the  globe,  are,  on  a 
clofe  infpe£lion,  found  to  belong  to  two  different  ftates  of  our  planet.  The  parts  of  vege- 
tables and  their  impreflions,  found  in  mountains  of  a  cotaceous  fchiftous,  or  even  fomctimes 
of  a  calcareous  nature,  are  chiefly  of  plants,  now  exifting  between  the  tropics,  which  could 
neither  have  grown  in  the  latitudes  in  which  they  are  dug  up,  nor  have  been  carried  and  depo- 

•  Hiftory  of  Embanking:  and  Draining,  chap,  xxvii.  f  Philof.  Tranf.  vol.  XXIf.  p.  980. 

X  Philof.  Tranf.  vol.  X/X.  p.  528. 

fited 


Submarine  Forejl  on  the  eaji  Coiift  of  England.  219 

fitcd  there  by  any  of  the  ac):ing  f  )rces  under  the  prefent  conftitution  of  nature.  The  form- 
ation, indeed,  of  the  very  mountains  in  which  they  are  buried,-  and  the  nature  and  dif^wfi- 
tion  of  the  mutcrijls  which  compofe  them,  are  fuch  as  we  cannot  account  for  by  any  of  the 
actions  and  re-a6tions  which  in  the  a^£lual  ftate  of  things  take  place  on  the  furface  of  the  earth. 
We  muft  neccflarily  recur  to  that  period  in  the  hiftory  of  our  planet,  when  the  fur  face  of 
the  ocean  was  at  Icaft  fo  much  above  its  prefent  level,  as  to  cover  even  the  fummits  of  thefc 
fecondary  mountains,  which  contain  the  remains  of  tropical  plants.  The  changes  which 
thefe  vegetables  have  fufFcred  in  their  fubftance,  is  almoft  total.  They  commonly  retain 
only  the  external  configuration  of  what  they  originally  were.  Such  is  the  ftate  in  which 
they  have  been  found  in  England  by  Llwyd ;  in  France  by  Juflieu  ;  in  the  Netherlands  by 
Burtin ;  not  to  mention  inftances  in  more  diftant  countries.  Some  of  the  impreflions,  or 
remains  of  plants,  found  in  foils  of  this  nature,  which  were,  by  more  ancient  and  Icis 
enlightened  ory^Sologifts,  fuppofed  to  belong  to  plants  actually  growing  in  temperate  and  cold 
climates,  feem,  on  accurate  inveftigation,  to  have  been  parts  of  exotic  vegetables.  In  fa6l, 
whether  we  fuppofe  them  to  have  grown  near  the  fpot  where  they  are  found,  or  to  have 
been  carried  hither  from  different  parts  by  the  force  of  an  impelling  flood,  it  is  equally  difE^ 
cult  to  conceive  how  organized  beings,  which,  in  order  to  live,  require  fuch  a  vaft  d  ifFerencc 
in  temperature  and  in  feafons,  could  live  on  the  fame  fpot,  or  how  their  remains  could  (from 
climates  fo  widely  diftant)  be  brought  together  to  the  fame  place  by  one  common  diflocat- 
ing  caufe.  To  this  ancient  order  of  foffil  vegetables,  belong  whateverj  retains  a  vegetable 
fhapc,  found  in  or  near  coal  mines  ;  and  (to  judge  from  the  places  where  they  have  been 
found)  the  greater  part  of  the  agatized  woods.  But  from  the  fpccics  and  prefent  ftate  of 
the  trees,  which  are  the  fubjeft  of  this  memoir,  and  from  the  fituation  and  nature  of  the  foil 
in  which  they  arc  found,  it  feems  very  clear  that  they  do  not  belong  to  the  primeval  order 
of  vegetable  ruins. 

The  fecond  order  of  foffil  vegetables  comprehends  thofe  which  are  found  in  the  ftrata  of 
clay,  or  (and ;  materials  which  are  the  refult  of  flow  depofitions  of  the  fea  or  of  rivers ; 
agents  ftill  at  work  under  the  prefent  conftitution  of  our  planet.  Thefe  vegetable  remains 
are  found  in  fuch  flat  countries,  as  may  be  confidered  to  be  of  a  new  formation.  Their  ve- 
getable organization  ftill  fubfifts,  at  leaft  in  part ;  and  their  vegetable  fubftance  has  fufFercd 
a  change  only  m  colour,  fmell,  or  conflftence  ;  alterations  which  are  ptoduced  by  the  devc- 
lopement  of  their  oily  and  bituminous  parts,  or  by  their  natural  progrefs  towards  rottennefs. 
Such  are  the  foffil  vegetables  found  in  Corrtwall  by  Borlafe;  in  Eflex  by  Dcrham;  in  York- 
ihire  by  de  la  Pryme  and  Richardfon  ;  and  in  foreign  countries  by  other  naturallifts.  1'hefe 
vegetables  are  found  at  different  depths,  fome  of  them  much  below  the  prefent  level  of  the 
fea,  but  in  clayey  or  fandy  ftrata  (evidently  belonging  to  modern  formation),  and  have  no 
doubt  been  carried  from  their  original  place,  and  depofited  there  by  the  force  of  great  rivers 
or  currents,  as  it  has  been  obferved  with  rcfpcft  to  the  Miffiffippi  *.     In  many  inftances, 

•  La  Conilrcnierc  fur  Its  Dcp6;s  du  Miffilfippi.    Journ.  dc  Phyf.  vol.  XXI.  p.  23c. 

however. 


220  Submarine  Forift  on  the  enft  Conji  of  England. 

Jiowever,  thefe  trees  and  fhrubs  are  found  ftanding  on  their  roots,  generally  in  \o'n  or  marihy 
places,  above,  or  very  little  below,  the  ^&^iA  level^of  the  fea. 

To  this  laft  defcription  of  foflil  vegetables,  the  decayed  trees  here  defcrtbed  certainly 
belong.  They  have  not  been  tranfported  by  currents  or  rivers^  but,  though  ftanding  in  their 
native  foil,  we  cannot  fuppofe  the  level,  in  which  they  are  found,  to  be  the  fame  as  that  in 
which  they  grew.  It  would  be  impoflible  for  any  of  thefe  trees  or  fhrubs  to  vegetate  fo  near 
the  fes,  and  below  the  common  level  of  its  water ;  the  waves  would  cover  fuch  tra£b  of  land, 
and  hinder  any  vegetation.  We  cannot  conceive  that  the  furface  of  the  ocean  has  ever  been 
lower  than  it  now  is ;  on  the  contrary,  we  are  led,  by  nu:nberlefs  phenomena,  to  believe 
that  the  level  of  the  waters  in  our  globe  is  much  below  what  it  was  in  former  periods  :  we 
mud,  therefore,  conclude,  that  the  foreft  here  defcribed  grew  in  a  level  high  enough  to  per- 
mit its  vegetation  j  and  that  the  force  (whatever  it  was)  which  dedroyed  it,  lowered  the  level 
of  the  ground  where  it  ftood. 

There  is  a  force  of  fubfidence  (particularly  in  foft  ground),  which,  being  a  natural  conic- 
quence  of  gravity,  flowly  though  perpetually  operating,  has  its  adlton  fometimes  quickened 
and  rendered  fudden,  by  extraneous  caufes  ;  for  inftance,  by  earthquakes.  The  flow  efFei^ 
of  this  force  of  fubfidence  have  been  accurately  remarked  in  many  places  ;  examples  alfo  of 
its  fudden  aflion  are  recorded  in  almoft  every  hiftory  of  great  earthquakes.  The  (hores  of 
Alexandria,  according  to  Dolomieu*s  obfervations,  are  a  foot  lower  than  they  were  in  the 
time  of  xkiz  Ptolemies.  Donati,  in  his  natural  hiftory  of  the  Adriatic,  has  remarked,  feem- 
ingly  with  great  accuracy,  the  efFeds  of  this  fubfidence  at  Venice ;  at  Pola,  in  Iftria ;  at 
LilTa,  Buaj  Zara,  and  Diclo,  on  the  coaft  of  Dalmatia.  In  England,  Borlafe  has  given,  in 
the  Philofophical  Tranfaftions  *,  a  curious  obfervation  of  a  fubfidence,  of  at  leaft  fixteen 
feet,  in  the  ground  between  Sampfon  and  Trefcaw  iflands,  in  Scilly.  The  foft  and  low 
ground  between  the  towns  of  Thome  and  Gowle,  in  Yorkfliirc,  a  fpace  of  many  miles,  has 
fo  much  fubfided  in  latter  times,  that  fome  old  men  of  Thome  affirmed,  "  That  whereas 
they  could  before  fee  little  of  the  fteeple  (of  Gowle),  they  now  fee  the  church-yard  wall  f  .'* 
The  inftanccs  of  fimilar  fubfidence,  which  might  be  mentioned,  are  innumerable. 

This  force  of  fubfidence,  fuddcnly  aSing  by  means  of  fome  earthquake,  feems  to  me  the 
moft  probable  caufe  to  which  the  aftual  fubmarine  fituation  of  the  foreft  we  are  fpeaking  of, 
may  be  afcribed.  It  affords  a  fimple,  cafy  explanation  of  the  matter,  its  probability  is  fop- 
ported  by  numberlefs  inftanccs  of  fimilar  events,  and  it  is  not  liable  to  the  ftrong  objections 
which  cxift  againft  the  hypbthefis  of  the  alternate  dcpreffion  and  elevation  of  the  level  of  the 
ocean ;  an  opinion  which,  to  be  credible,  requires  the.fupport  of  a  great  number  of  proofs  ; 
lefs  equivocal  tlKin  thofc  which  have  hitherto  been  uigcd  in  its  favour,  even  by  the  genius  of  ' 
a  Lavoificr  J. 

*  Vol  XLVJII.  p.  62.  ■(-  Cough's  edicioD  of  Cacndca*s  Bminnlca.  t.  111.  p.  35. 

\  Mem.  dc  TAcid,  dc  Paris,  17S9,  p.  351. 

The 


On  apbmarint  Fttfe/I  on  the  eqfi  Coaji  of  Enfland.  %i  x 

The  ftratum  of  foil,  fixteen  feet  thick,  placed  above  the  decayed  trees,  feems  to  remove  the 
epoch  of  their  finking  and  deftru£lion  far  beyond  the  reach  of  any  hiftorical  knowledge.  In 
Caefar's  time,  the  level  of  the  North  Sea  appears  to  have  bcert  the  fame  as  in  our  days.  He 
mentions  the  feparation  of  the  Wahal  branch  of  the  Rhine,  and  its  junftion  to  the  Meufe ; 
noticing  the  then  cxifting  diftance  from  that  junftion  to  the  fea,  which  agrees  according  to 
D'Anville's  inquiries  *  with  the  acSlual  diftance.  Some  of  the  Ronoan  roads,  conftrufted, 
according  to  the  order  of  Auguftus,  under  Agrippa's  admini  ft  ration,  leading  to  the  maritime 
towns  of  Belgium,  ftill  exift  and  reach  the  prcfent  fhore  f.  The  defcriptions  which  Roman 
authors  have  left  us  of  the  coafts,  ports,  and  mouths  of  rivers,  on  both  fides  of  the  North 
Sea,  agree  in  general  with  their  prefcnt  ftate ;  except  in  the  places  ravaged  by  the  inroads  of 
this  fea,  more  apt  from  its  form  to  deftroy  the  furrounding  countries,  than  to  increafii 
them. 

An  exaft  refemblance  exifts  between  maritime  Flanders,  and  the  oppofite  low  coaft  of 
England,  both  in  point  of  elevation  above  the  fea,  and  of  internal  ftrufture  and  arrangement 
of  their  foils.  On  both  fides  ftrata  of  clay,  filt,  and  fend  (often  mixed  with  decayed  vege- 
tables), are  found  near  the  furface  ;  and,  in  both,  thefe  fuperior  materials  cover  a  very  deep 
ftratum  of  blui(h  or  dark  coloured  clay,  unmixed  with  extraneous  bodies.  On  both  fides  they 
«re  the  lowermoft  part  of  the  foil,  exifting  between  the  two  ridges  of  high  lands  %  on  their 
refpe£live  fides  of  the  fame  narrow  fea.  Thefe  two  countries  are  certainly  coeval,  and  what- 
ever proves  that  maritime  Flanders  has  been  for  many  ages  out  of  che  fea,  muft,  in  my  opi- 
nion, prove  alfo  that  the  foreft  we  are  fpeaking  of  was  long  before  that  time  deftroyed  and 
buried  under  a  ftratum  of  foil.  Now  it  feems  proved  from  hiftorical  records,  carefully  col- 
Ie£led  by  feveral  learned  members  of  the  Bruflels  academy,  that  no  miterial  change  has  hap- 
pened to  the  lowermoft  part  of  maritime  Flanders,  during  the  period  of  the  laft  two  dioufand 
years  §. 

I  am,  therefore,  inclined  to  fuppofe  the  original  cataftrophe,  which  buried  this  foreft,  to  be 
of  a  very  ancient  date  ;  but  I  fufpedt  the  inroad  of  the  fea,  which  uncovered  the  decayed  trees 
of  the  iflets  of  Sutton,  to  be  comparatively  recent.  The  ftate  of  the  leaves  and  of  the  tim- 
ber, and  alfo  the  tradition  of  the  neighbouring  people,  concur  to  ftrengthen  this  fufpicion. 
Leaves,  and  other  delicate  parts  of  plants,  though  they  may  be  long  preferved  in  a  fubterra- 
neous  fituation,  cannot  remain  uninjured,  when  expofed  to  the  a£lion  of  the  waves  and  of  the 
air.  The  people  of  the  country  believe  that  their  parifh-church  once  ftood  on  the  fpot  where 
die  iflets  now  are,  and  was  fubmerged  by  the  inroads  of  the  fea ;  that  at  very  low  water  their 

•  D'Anville  Notice  dts  Gaules,  p.  461, 

f  Nicol.  Bergier.  Hift.  dcs  grands  Ctiemlns  des  Romains.    Kd.  de  Bruzelles,  vol.  II.  p.  109. 

\  Thefe  ridges  o£  higK  land,  both  on  the  Britiih  and  the  Bcli^ic  fide,  muft  be  very  fimilar  to  each  other, 
iince  they  both  contain  parts  of  tropical  plants  in  a  foflil  (late.  Cocoa  nuts,  and  fruits  of  tlic  arecas  are 
found  in  the  Bclgic  ridge.  The  petrified  fruits  of  Sheppcy,  and  other  iraprcffions  of  tropical  plants  on  this 
fide  of  the  water,  are  well  known. 

§  Vide  feveral  papers  in  the  BrafTels  Mgmoirs  ',  alfo  Journ.  Phyf.  t«  XXXIV*  p.  401. 

Vol.  Ill AucrsT  1799,  Gg  anceftors 


aaa  On  the  unequal  ReftexlbiUty  of  Light. 

anceftors  could  even  difcover  its  ruins ;  that  their  prefent  church  was  built  to  Aipply  the  place 
of  that  which  the  waves  waflied  away  ;  and  that  even  their  prefent  clock  belonged  to  their  old 
church.  So  many  concomitant,  though  weak  teftimonics,  incline  me  to  believe  their  report, 
and  to  fuppofc  that  (bme  of  the  ftormy  inundations  of  the  North  Sea^  which,  in  thefe  Jaft 
centuries,  have  waflied  away  fuch  large  tradls  of  land  on  its  fhores,  took  away  a  foil  rcfting 
on  clay,  and  at  laft  uncovered  the  trees  which  are  die  fubjecl  of  this  paper. 


imm 


IX. 

Opticeil  Remarks^  chiefly  relating  to  the  Refexibility  of  the  Rays  of  Light  *.  By  P,  PrEFOST^ 
Prcfejfor  of  Phikfophy  at  Geneva^  cf  the  Academy  of  Berlin^  of  the  Society  des  Curieux  dc 
la  Nature^  and  of  the  Royal  Society  of  Edinburgh. 


p 


ART  I.  Concerning  reflexibility.     Se^ion  i.  The  word  reffexibility  is  ufed  in  two- 
different  fenfes. 

I.  Newton  f  indicates,  by  this  word,  that  property  of  a  ray  of  homogeneous  light,  by 
virtue  of  which  this  ray  is  refleded,  if  it  fall  under  a  certain  angle  of  incidence ;  and  trans- 
mitted, if  it  fall  under  a  certain  fmallcr  angle:  or,  more  Amply,  a  difpofition  to  be  reflededm. 
and  not  tranfmitted  at  the  limit  which  feparates  two  refracting  mediums  :|:. 

This  philofopher  thinks  that  the  reflexibility  of  the  rays  of  light,  taken  in  this  fenfe,  is  not 
the  fame  in  all  the  feveral  kinds.  He  e(labli(hes,  by  experiments,  which  he  concludes  to  be 
decifive,  that  the  moft  refrangible  rays  are  alfo  the  mofl  reilexible.  So  that,  according  to  him^ 
all  other  circumftances  being  the  (ame,  if  a  white  ray  fall  undbc  a  certain  angle  on  the  direA-« 
ing  furface,  the  violet  ray  will  be  refledlcd,  while  the  fix  others  will  be  ftill  tranfmitted  and 
xefraded.  But  by  augmenting  the  angle  of  incidence,  the  fucceffive  reflection  of  all  the  rays 
VfiW  be  obtained  from  the  violet^  which  is  the  moft  reflexible,  to  the  red,  which  is  the 

leaflfo.  - 

Mr.  Brougham  §  does  not  find  the  experiments  of  Newton,  by  which  he  eftablifhes  this 
propoiition,  conclufive :  and,  upon  the  foundation  of  another  experiment,  he  eftablifhes  the 
contrary  proportion  \  namely,  that  all  the  rays  have  the  fame  difpofition  to  be  refleded,  pro- 
vided the  angle  of  incidence  be  the  fame. 

2.  Mr»  Brougham  underfbnds  by  reflexibility,  a  difpofition  in  the  ray  to  be  refleded 
nearer  to  the  perpendicular,  to  a  certain  degree ;   or,  in  other  words,  a  property'  of  the 
homogeneous  ray,  by  which  its  angle  of  reflexion  bears  a  certain  ratio  to  its  angle  of 
incidence,  which  is  not  the  ratio  of  equality,  except  in  certain  cafes,  which  he  points  out- 
According  to  this  philofopher,  the  above  ratio  varies  in  each  homogeneous  ray.     The  ratio 

*  TranfUced  from  the  French  original,  in  the  PhiloC  Tranf.  1798. 

f  Opt.  L  i.  part  i.  prop.  3.  }  Opt.  1.  i.  part  i.  defin.  3. 

{  Fbilof.  Tranf.  1796.  p.  272.  or  Philof.  Journal,  i.  595* 

rf 


On  the  unequal  Reflexibillfy  cf  Light.  223 

of  equality  takes  place  in  thofe  rays,  which  occupy  the  confines  of  the  blue  and  green :  that 
of  inequality  takes  place  with  regard  to  the  others,  and  the  moft  refrangible  one  the  Icaft 
reflexible.  So  that  with  regard  to  the  red  ray,  the  angle  of  refra£iion  is  Icfs,  and  in  the 
violet  greater,  than  the  angle  of  incidence. 

It  is  known  that  Newton,  on  the  contrary,  affirms  that  the  angle  of  reflexion  is,  in  all 
cafes,  equal  to  the  angle  of  incidence. 
Let  us  examine  thefe  oppofite  opinions. 

Sexton  2.  Thefirfi  queftlon.  Do  the  homogeneous  rays  of  light  differ  in  reflexibility  in  the 
Newtonian  fenfe  of  the  term  ?  Or,  more  direcElly  ;  does  it  happen,  in  faft,  that  the  violet  ray 
will  be  refle£let]  under  the  fame  angle  of  incidence  at  which  the  red  ray  Is  tranfmitted,  all 
other  circumftances  being  precifely  the  fame  ? 

Of  the  two  experiments  by  which  Newton  eftabliflies  the  unequal  reflexibility  of  the  rays, 
it  will  be  fufficicnt  to  mention  that  which  Mr.  Brougham  attacks  direftly. 

Newton  caufed  a  white  ray  to  fall  perpendicularly  upon  the  anterior  furface  of  a  prifm  ; 
after  which,  turning  the  prifm  on  its  axis,  he  obferved  the  reflexion  which  took  place,  from 
its  |>ofterior  furface.  He  faw  that  the  violet  ray  was  firft  rcflcftcd  ;  and  afterwards,  the  other 
rays  in  the  order  of  their  refrangibilities,  the  red  ray  being  reflefted  the  laft.  Whence  he 
concludes,  that  the  violet  ray  is  refleded  under  a  lefs  angle  of  Incidence  than  the  red.  Expe* 
riment  9. 

This  is  the  concludon  which  Mr.  Brougham  attacks ;  and  to  avoid  altering  his  thought,  I 
fliall  here  tranfcribe  his  expreflions.  "  That  the  dcmonftration  involves  a  logical  error, 
appears  pretty  evident.  When  the  rays,  by  refraftion  through  the  bafc  of  the  prifm  ufcd  in 
^e  experiment,  are  feparatcd  intp  their  parts,  thefe  become  divergent,  the  violet  and  red 
emerging  at  very  different  angles  ;  and  thefe  were  alfo  incident  on  the  bafe  at  different  angles, 
from  the  refradlion  of  the  fide  at  which  they  entered  :  when,  therefore,  the  prifm  is  moved 
round  on  its  axis,  as  defcribed  in  the  propofition,  the  bafe  is  nearcft  the  violet,  from  the 
pofition  of  the  rays  by  refradlion,  and  meets  it  firft :  fo  that  the  violet  bciiig  refledted  as  foon 
as  it  meets  the  bafe,  it  is  refledled  before  any  of  the  other  rays,  not  from  a  different  difpofi* 
tion  to  be  fo,  but  merely  from  its  different  refrangibility." 

So  that  Mr.  Brougham  thinks  that  the  refledion  of  the  violet  ray  does  not  precede  that  of 
die  red  ray ;  but  becaufe  the  rcfradlion  which  takes  place  at  the  anterior  furface,  forces  the 
violet  ray  to  arrive  at  the  pofterior  furface  fooner  than  the  red  ray* 

But  it  feems  that  the  effeft  is  here  the  inverfc  of  its  caufe.  Let  us  firft  exclude  a  falfe  (enfc 
of  the  words.  It  is  impoffible  that  the  author  can  mean  to  fay  that  the  eye  is  capable  of 
appreciating  the  interval  of  time,  between  the  arrival  of  the  violet  and  the  red  ray  at  the 
pofterior  face  of  the  prifm.  However,  that  ray  which  defcribes  the  (hortcft  courfe,  fells 
neareft  the  perpendicular  let  fall  from  the  point  of  departure;  and  from  this  circumftance 
alone,  we  can  conclude  that  its  angle  of  incidence  is  fmaller.  Whence  it  follows,  that  the  red 
jay  ought  to  be  refledled  the  firft,  and  not  the  violet. 
Let  us,  in  fa£l,  confidcr  the  pofition  of  the  prifm  at  the  firft  moment,  as  it  Is  reprefented 

G  g  2  in 


224  On  the  unequal  SeflesiUKty  cf  Light, 

in  the  optics  of  Newton.  The  white  ray  F  M,  plate  xvi.  fig.  x,  if  perpendicular  to  A  C  ^' 
anjd,  in  this  cafe,  it  is  not  refraded,  but  defcribes  a  right  line.  At  this  point,  Newton  re« 
prefcnts  the  violet  ray  M  N  as  alone  refleded  j  while  all  the  others,  fuch  as  M  H,  M  I,v 
ore  tranfmitted  and  refra£):ed  (at  leaft  the  violet  alone  is  totally  refled^ed). 

It  !•?,  neverthelcfs,  certain,  that  in  order  to  obtain  this  phenomenon,  it  was  requifite  to 
give  the  proper  degree  of  inclination,  by  turning  the  prifm,  in  order  that  the  experiment 
might  fucceed :  and  Mr.  Brougham  has  very  properly  obferved,  that  the  perpendicularity  of 
the  ray  on  the  anterior  face  A  C  mud  then  ceafe  ^  confequently,  there  muft  have  been 
refra£lion,  and  the  fcveral  homogeneous  rays  could  not  have  followed  a  right-lined  courfei  fuch 
as  F  M,  nor  have  fallen  on  the  pofterior  face  B  C,  under  equal  angles. 

Let  A'B'C,  fig,  2,  be  the  new  pofition  of  the  prifm,  which  it  has  taken  by  virtue  of  it9' 
notation  on  its  axis ;  the  ray  F  P  will  then  fall  obliquely  upon  A  C,  at  the  point  P,  fo  that 
the  perpendicular  P  O  may  be  on  the  fide  A,  and,  conf^^quently,  comprized  in  the  angle 
APF.  The  refult  will  be,  i.  What  Newton  propofcd,  nimely,  to  increafe  the  angle  of 
incidence  on  the  poflerior  furface ;  which  angle  (formed  at  the  point  M,  in  fig.  i,  which 
reprefents  the  firft  pofition  of  the  prifm)  was  before  too  foiall  to  produce  refle£lion;  and^ 
2.  The  prccife  expreilions  of  Newton  affirm,  that  the  prifm  was  turned  on  its  axis,  accord* 
ing  to  the  direction  indicated  by  the  order  of  the  letters  A  B  C,  in  his  figure,  which,  as  £tf 
as  relates  to  my  obje£t,  is  the  fame  as  my  figure  i. 

The  ray  F  P,  fig.  2,  will,  therefore,  be  refradl^d,  in  approaching  the  perpendicular  O  P, 
but  the  moft  refrangible  ray  (the  violet)  will  approach  the  neareft,  and  the  leaft  refrangible 
will  be  the  fartheft  off.  So  that  the  courfes  of  the  rays  refpedlively,  will  be  well  reprefented^ 
by  the  lines  P  V,  PR.  The  violet  ray  will,  therefore,  make,  widu  the  pofterior  fiice  B  C, 
an  angle  P  V  C,  greater  than  the  angle  P  R  C,  formed  by  the  red.  Now  the  angles  of  in- 
cidence at  the  points  V,  R,  are  the  complements  of  the  angles  P  V  C,  P  R  C,  refpec- 
tively- 

It  is,  therefore,  certain,  that  by  virtue  of  the  refra£^ion,  which  is  produced  at  the  anterior 
furface,  the  violet  ray  meets  the  pofterior  furface  under  a  lefs  angle  of  incidence  than  the 
red ;  and,  confequently,  the  former  is  under  lefs  favourable  circumftances  for  refle6lion  than 
the  latter ;  yet  the  former  is  reflefted  before  the  latter.  We  are,  therefore,  right  in  conclud- 
ing, that  it  is  in  its  own  nature  more  reflexible,  in  the  Newtonian  fenfe  of  the  word  *. 

This  very  proper  confideration,  which  was  introduced  by  Mr.  Brougham,  affords^ 
therefore,  a  ft  ill  ftronger  conclufion  in  favour  of  the  Newtonian  afTertion.  We  may  fay, 
that  the  violet  is  not  only  refleded  at  the  fame  incidence  at  which  the  red  is  tranfmitted  ;  but^ 
likewife,  that  this  phenomenon  takes  place,  though  the  angle  of  incidence  of  the  violet  be 
more  unfavourable  to  refle£lion  than  that  of  the  red. 

*  This  reafoning  is  equally  applicable  to  the  tenth  experiment  of  Newton,  in  which  he  nfes  two  prifint 
{oined  together,  te  form  one  parallelopipedon.  In  both  the  experiments  (9th  and  loth)^  another  acceflbry 
prifm  was  ufcd,  to  render  the  efie6t  more  fenfible,  by  difperfing  the  refledtlng  ray$.  It  was  unneceflary  to 
attend  to  this. 


Oft  iht  unequal  ReflemliBtf  tf  Ltght.  ^  «- 

Iha  word,  therefore,  the  rays  differ  in  rcflexibility  in  the  Newtonian  fenfe,  and  the  moft- 
ftftangible  is  alfo  the  moft  rcflexible. 

Thus  far,  in  order  to  give  fimplicity  to  my  argument,  I  have  left  the  refraftrng  angle  G, . 
of  the  prifm,  undetermined.  Newton  determines  it  in  the  ninth  experiment  of  the  firft  book 
#f  his  optic*,  part  i.  He  ufed  a  refnicting  angle  of  45^;  and,  neverthelefs,  he  fays  cx- 
prefsly,  that  the  rays  entered  perpendicularly ;  whence  it  follows,  that  the  angle  of  incidencd 
at  the  point  M  was  alfo  45^  We  fliould,  therefore,  be  juftified  in  thinking,  that  rays 
felling  under  this  angle  of  incidence  on  the  fiirface  B  C,  pafling  from  glafs  to  air,  arc  not 
totally  reflected  :  BriHon  affirms  this  to  be  the  cafe,  when  he  explains  this  fame  experiment  in 
bis  Elementary  Trcatife  of  Natural  Philofophy,  printed  at  Paris,  in  the  year  1789.  vol.  II.  § 
141 1.  Neverthelefs,  it  is  well  tnown  that  the  total  reflexion  takes  place  at  a  fmaller 
angle,  that  is  to  fay,  about  40*^.  This  has  been  determined,  even  with  the  utmofl:  precifion^ 
for  which  I  will  quote  only  a  finglc  authority.  **  A  ray  of  light  will  not  pafs  out  of  glafs 
into  Jiir,  if  the  angle  of  incidence  exceeds  40**  ii'.'*  Ad.im*s  Leftures  on  Natural  and 
Experimental  Philofophy,  London,  1794.  ii«  163.  The  determination  of  Newton  does  not 
fcnfibly  differ  from  this:  "  Totalis  rcflexio  tum  incipit,  cum  angulus  incidentiae  fit  40^  loV* 
Opt.  II.  p.  3.  prop.  I.  Can  we  affirm  that  under  the  angle  of  ^5^,  there  ftill  pafles  a 
fiifficient  number  of  rays  to  render  the  experiment  prcceptible?  Or  muft  we  fuppofe  that 
the  ray  F  M,  was  not  exactly  perpendicular  to  thr:  face  A  C  ?  I  think  the  latter  is  the  trudi  % 
that  is  to  fay,  that,  in  the  firft  pofition  of  the  prifm,  the  ray  began  by  being  oblique  to  A  C, 
in  the  oppolite  fituation  to  that  indicated  in  fig.  2.  So  that  the  angle  A  P  F  was  Icfs  than 
F  PC.  Whence  it  would  refult,  that  the  moft  refrangible  rays  would  fall  on  the  pofterior- 
furfaoe,  B  C,  under  a  greater  angle  of  incidence,  and,  therefore,  more  fevourable  to  reflec- 
tion.    Under  this  form  the  argument  of  Mr.  Brougham  acquires  new  force. 

The  optics  of  Newton,  in  this  place,  requires  a  comntcntaryit  The  beft  will  bft  that 
which  his  Leftiorcs  Opticae  prefcnt  us— 7/1  Newtoni  OpufcuU  Laujanna  et  Geneva^  1744. 
ii.  217.  223.  Here  the  author  replies  to  our  doubts  as  follows:  **  Ne  qua  oriatur  furpicio, 
quod  rcfracliones  in  fuperficiebus,  AC  et  A  B,  ad  ingrefliim  radiorum  in  prifma  et  egfef- 
fum  fafta,  poffint  aliquid  conducere  ad  efFcftus  hofce  producendos,  obfervare  licet  quod 
efFeftus  iidcm  producuntur,  ctijufcunque  magnitudinis  ftatuatur  angulus  A  C  B  *  ;  hoc  eft, 

quaecunque  fit  refradio  (upcrficiei  AC Imo  poffis  efficere  quod  cum  colores  partim 

refleftuntur  .  .  .  .  et  partiin  trajiciuntur radii  perpendiculariter  incidant  in  AC, 

cmergantque  ex  A  B,  et  fic  neutra  fuperficie  refringantur,  modo  ftatuas  angulum  A  C  B, 
ciTe  grad.  40  circiter,  et  iidem  tamen  efte^tus  producentur  f.''  p«  219.    The  moft  accurate 

writers 

♦  It  it  AB  C,  in  the  teirt  ;  nnnifcdly  by  an  error  of  the  prcfs.  This  is,  indeed,  of  no  confequence  to 
my  objca.  I  do  not  quote  what  reUtei  to  the  cquility  required  between  the  angles  B  and  C,  becaufe  it  doef 
Hot  affed  the  prefent  enquiry. 

t  Anglke.  Led  any  fufpicion  i&ould  triff,  that  the  rcfniaions  at  the  furfacet  AC,  and  A  B,  at  the 
^  entrance 


ft 26  On  the  unequal  Reflexihility  of  Light, 

writers  have  not  overlooked  this  circumftance.  Robert  Smith}  after  having  explained  tbe 
9th  experiment  of  Newton^s  Optics,  fays,  or  makes  Newton  fay,  "  I  did  not  obfirrve  any 
refradion  at  the  fides  A  C,  A  B,  of  the  firft  prtfm,  becaufe  the  light  was  nearly  perpendi- 
cular to  the  firft  fides,  and  emerged  nearly  perpendicular  to  the  fecoiid;  and,  in  confequenc^ 
underwent  none,  orfo  little,  that  the  angles  of  incidence  at  the  bafe  B  C  were  not  fenfiblj^ 
altered;  particularly  if  the  angles  of  the  prifm  at  the  bafe  B  C  were  each' about  40**.  For 
die  rays  F  M  begin  to  be  totally  reflected  when  the  angle  C  M  F  is  about  50^ ;  and, 
confequently,  they  will  then  form  an  angle  of  90**  with  A  C."  Smith's  Optics  tranjlatei 
into  French^  by  L.  P.  P.  (Pezenas).  i,  §.  173.  y..  190*. 

From  all  this  it  follows,  that  when  the  angle  of  a  prifm  is  well  chofen,  a  white  ray,  Ming 
'  perpendicularly  on  its  anterior  furface  A  C,  may  be  decompofed ;  becaufe  it  is  partly,  and  not 
totally,  reflected,  the  violet  ray  being  refledted  while  the  red  is  ftill  tranfmitted. 

I  mud  here  remark,  that  in  order  to  repeat  this  experiment,  and  render  it  concluCve,  it  is 
not  neceflary  to  circumfcribe  the  angle  C,  within  the  limits  which  render  the  ray  F  M  per- 
pendicular (or  nearly  fo)  to  the  anterior  face  A  C.  All  the  reafoning  we  have  offered  on 
this  head  (§  2.)  will  be  jufl,  provided  that,  in  the  firfl  pofition  of  the  prifm,  the  angle 
A  P  F  be  greater  than  its  fupplement  F  P  C.  But  in  order  that  this  circumftance  fhould 
take  place,  when  the  refledtion  is  made  at  the  point  M,  it  is  fufficient  that  the  refra^ng 
angle  C  be  lefs  than  40^ 

Interefting  refults  may  be  obtained,  by  varying  this  experiment ;  but  the  authorities  I  have 
quoted,  leave  no  doubt  with  regard  to  the  particular  refult,  which  we  have  to  examine.  The 
mojl  refrangible  rays  are  reile6ted  at  a  lefs  angle  of  incidence.  They  are  more  reflexible  in 
the  Newtonian  fenfe. 

Se<Slion  3.  But  Mr.  Brougham  fupports  the  contrary  opinion,  by  an  experiment  which  he 
Aus  annourK:es,:  <<  I  helc^  prifm  vertically,  and  let  the  fpedlrum  of  another  prifm  be  reflected 
by  the  bafe  of  the  former,  fo  that  the  rays  had  all  the  fame  angle  of  incidence;  then  turning 
round  the  vertical  prifm  on  its  axis,  when  one  fort  of  rays  was  tranfmitted  or  reflected,  all 
were  tranfmitted  or  reflcftedf.'* 

As  tbe  complete  difcuffion  of  this  experiment  would  require  fome  detail,  I  (hall  content 
myfelf  with  obferVing,  that  the  plane  of  the  vertical  face  cannot  be  adjufted^  fo  as  to  receive 

entrance  and  emergence  of  the  rays,  with  regard  to  the  prifm,  might,  in  fomc  reipe^^,  affift  in  producing 
tbefe  effects,  it  may  be  obferved,  that  the  fame  ctfc€ts  are  produced,  whatever  may  be  the  magnitudes  of  the 

angle  AC  B  ;  that  i^  whatever  may  be  the  refraction  of  the  furface  AC It  may  even  be  contrived, 

chat,  when  the  colours  are  partly  rcfiedted  ....  and  partly  tranfmitted the  rays  may  fall  peipendt* 

cularly  on  A  C,  and  A  B,  at  their  entrance  and  emergence,  and  they  be  refracted  by  neither  furface,  pro- 
Tided  the  angle  A  C  B  be  made  of  about  40^,  and  yet  the  fame  effects  are  produced.     N. 

'*  The  palTage  here  marked  as  quotation,  it  retranflated  from  the  French;  andp  confequeiitly,  it  not  gi\ien 
in  the  very  words  of  Smith,  whofe  work  I  have  not.    N. 

f  The  fame  experiment,    tried  by  Newton,  afforded  precifely  the  contrary  refult.    **  Radii  purpuri- 
loKnet  primo  omnium  refle^untur  ct  ultimo  rubriformct."    Led.  Opt.  Opufcul.  ti.  120. 

all 


On  tie  unequal  Reflexihillty  of  Lights  ^vj 

all  the  rays  of  the  fpeAnim  at  once  under  the  fume  angle  ;  and  even  ruppofing  this  to  have 
been  poi&ble,  and  done  for  an  inftant,  yet  the  rotation  of  the  pri(m  would  have  changed  this 
di/pofltion)  by  altering  this  angle  with  regard  to  the  feveral  rays.  We  may,  confequently» 
imagine  a  variety  of  different  refults  j  and,  among  others,  we  may  conceive  the  angles  of  incidence 
of  the  feveral  rays  to  be  fuch,  that  the  obfervation  of  Mr.  Brougham  may  be  reconciled  with  the 
opinion  of  Newton,  on  their  unequal  rcflexibility.  But  fince  Mr.  Brougham  does  not  enter 
into  this  detail,  and  gives  only  a  fingle  refult,  it  is  to  be  prefumed,  that  he  has  not  repeated, 
or  at  leaf):  varied,  this  experiment.  I'his  philofopher  even  appears,  by  his  rapid  enunciation^ 
to  have  confidered  it  of  no  very  great  importance. 

1  think,  therefore,  that  it  cannot  at  prefent  weaken  the  conclufions  of  Newton  ;  and  Aat 
we  are  ftill  juftificd  in  affirming,  in  the  fenfe  of  that  philofopher,  that  the  moft  refrangible 
rays  are  alfo  die  moft  reflexible. 

Section  4.  Second  question.  Do  the  rays  of  light  differ  in  rcflexibility,  in  the 
Broughamian  fenfe  ?  In  other  words^  does  the  red  ray  at  the  fame  angle  of  incidence  form  a 
lefs  angle  of  refledlion,  and  the  violet  a  greater,  than  the  angle  of  incidence  } 

Se^ien  5.  The  fundamental  experiment  from  which  Mr.  Brougham  deduces  this  unequal 
reflexibility  in  the  fenfe  of  his  definition,  is  this  : 

A  bright  polifhed  cylinder,  of  very  fmall  diameter  (a  metallic  fibre),  having  its  convex 
furface  prefented  to  a  white  ray,  refle<^ed  a  coloured  fpedlrum ;  and  after  proper  admeafure- 
ment  and  computation,  it  appeared  that  the  rays  in  the  confine  of  the  blue  and  green,  were 
alone  refledled,  under  an  angle  equal  to  that  of  the  incidence.  The  red  rays  were  reflected 
under  a  lefs  angle,  and  the  violet  under  a  greater*. 

The  queftion,  therefore,  is  reduced  to  determine,  whether  this  experiment  be  conclufive  in 
favour  of  Mr.  Brougham. 

Se£fion  6.  To  afcertain  this,  it  is  of  importance  to  advert  to  a  principle  laid  down  by  New- 
ton, and  admitted  by  Brougham,  p.  250.  (or  Philof.  Journal,  i,  561),  namely,  that  the  force, 
whatever  it  may  be,  that  produces  reflexion,  zJSts  In  the  dire£Uon  of  a  line,  perpendicular  to 
the  reflefting  flirfcice. 

Se^iion  7.  From  this  principle  it  follows,  that  the  refle£lion  operated  by  a  plane  furface, 
muft  be  made  according  to  the  law  hitherto  admitted  by  all  opticians  (Newton's  Princip.  I.  k 
p.  96).  And  this  is  true,  whatever  maybe  the  intenfity  of  the repulfive  force,  and  the  incli- 
nation of  the  incident  ray;  provided  the  ray  be  really  incident,  and  do  not  move  parallel  to 
the  repulfive  furface. 

SeSiion  8.  This  confequence,  and  the  whole  of^the  Newtonian  demonftration,  fuppofes  that 
the  furface  a£b  on  the  ray  during  its  whole  courfe  through  the  fphere  of  its  aAivity ;  and 
equally  at  equal  diftances.  Mr.  Brougham  alleges  nothing  againft  this  hypothefis,  but  even 
feems  to  admit  it  exprefsly'(p.  269,  or  Ph.  Journal,  i.  593) ;  and  indeed  how  can  it  be  denied? 

SeSiiw  9.  Therefore,  from  a  principle  which  is  not  contefted,  it  appears  that  refle^on 
cannot  decompofe  white  light,  when  it  is  made  totally  from  a  plane  furface. 

This  is  perfe^y  conformable  ta  the  obfervation  of  Mr»  Brougham,  that  thert  is  no  mean 


of  eOc&,\ng  this  decomporition  by  employing  plane  furfaces,  nor  curve  fur&cei^  I7?hichhave 
not  1  very  minutc>  and,  as  it  were,  evanefcent  radius.  It  may^  in  iz&^  be  conceived,  that  a 
foiall  portion  of  a  curved  furface  of  a  greater  radius  is  a  plane  with  regard  to  a  particle  of 
light  The  author  indeed,  explains  this  phenomenon  in  another  manner;  but  the  fail, 
independent  of  all  explanation,  js  no^  the  lefs  certain  and  acknowledged. 

Se^ioH  10.  Let  H  H  H,  fig.  3,  now  reprefent  a  very  fmall  bright  poliflied  cylinder  (a  metallic 
fibre),  and  B  R  V  K  the  cylinder  on  the  /ame  axis,  which' is  the  fphere  of  aSivity  of  this 
(mall  body :  each  of  them  being  reprefcnted  by  its  circular  fedtion.  (Thefe  two  circles, 
though  very  unequal,  are  confounded  together  in  aAual  obfervation.) 

A  B  reprefents  a  white  ray,  incident  at  the  point  B,  on  the  cylinder,  on  its  fphere  of 
aftivity.  • 

Suppofc  the  homogeneous  rays  to  be  unequally  repulfive,  and  that  the  red  be  more  ftrongly 
•repelled  than  the  violet:  Mr.  Brougham  admits  this  fuppofuion  (p.  2679  or  Pbilof.  Jour* 
ual,  i.  59a). 

On  this  hypotheiis,  the  violet  ray  muft  penetrate  farther  into  the  fphere  of  repulfion. 

The  courfe  Jefcribed  by  an  homogeneous  ray,  within  the  fphere  of  repulfive  adlivity,  muft 
be  formed  of  two  equal  and  fimilar  branches :  and  its  axis  muft  pafs  through  the  centre  of  the 
fphere  or  fedion.     This  follows  from  the  principle  before  laid  down  (.§  6). 

And  it  is  an  inunediate  xronfcqucnce  of  this  remark,  that  this  homogeneous  ray  will  iStia 
.from  the  fphere  of  adivity,  under  an  angle  of  refleflion  equal  to  the  angle  of  incidence. 

So  that  all  the  homogeneous  rays  forming,  in  B,  the  fame  angle  of  incidence,  will  be 
refleded  under  equal  angles. 

But  fince  fome  penetrate  farther  Into  the  fphere  of  activity  than  others,  they  will  come  out 
divergent ;  for  this  is  the  only  condition  by  which  the  equality  of  the  angles  of  refie^^ion  can 
•be  preferved. 

-Fig.  3  is  intended  to  fhew  this  effeft.  The  red  ray  penetrating  Icfc  into  the  fphere  oc 
.cylinder  of  aftivity  B  R  V  K,  defcribes  the  curve  B  O  R,  the  axis  of  which  paffes  through 
the  centre  Cj  and  it  emerges  through  R  Cy,  making  the  angle  of  refle^on  K  R  G  s 
A  B  D,  the  angle  of  incidence.  The  violet  ray,  penetrating  deeper,  defcribes  the  curve 
B  Q  V,  of  which  the  axis  likewife  paiTes  through  C.  Tht^  ray  emerges  through  V  L,  and 
.the  three  angles  F  VL,  ERG,  ABD,  are  equal. 

But  the  obferver  feeing  the  arc  B  R  V  like  a  point,  and  knowing  that  the  angles  which 

%e  meafures  are  the  fum  of  the  angle  of  incidence  and  of  reflection  for  the  raya  of  each 

kind,  will  be  ind»ced-to  think,  that,iunder  the  fame  angle  of  incidence,  the  angles  of  reflec- 

•tfon  vary:  for  he  will  find  thatthe  right  lin^  AB,  forms  unequal  angles  with  the  right  lines 

RG,  VL;  and,  in  a  word,  he  will  have  aU  the  fiune  appearances  wUch  prefented  diem- 

ielves  to  Mr.  Brougham  (^  5)« 

It  is  of  importance  to  remark  here,  that  though  this  philofbpher  affirms  that  the  rays  on 
fthe  confine  of  blue  and  green  are  refiefted  under  an  angle  of  reflection  equal  to  the  angle 
(^.incideacf,  ^he  did  no^  nor  ^could^nolf  aicertaia  thi«  equality  by  aAy-diftft  c«periaient :  it 

waa 


Reflelflon  of  LighU'^Oil  from  the  Beech-nut.  229 

was  fimply  the  moft  natural  fuppodtion  he  could  make.  And  if  it  had  been  pretended,  that 
all  the  angles  of  reflexion  are  fmaller,  or  all  greater  than  thofe  of  incidence ;  or  that  the 
limit  of  equality  falls  on  any  other  divifion  of  tlie  fpeSrum,  the  fuppofition  would  have  been 
gratuitous,  but  againft  which  the  obferver  could  oppofc  no  direft  fail.  For  there  is  no  con- 
ceivable means  by  which  the  angle  of  incidence  can  be  mcafured  in  thcfj  experiments,  di- 
rc6lly  and  apart  from  that  of  reflcftion. 

Sexton  II.  Since,  therefore,  by  fappofing  (with  Mr.  Brougham)  that  the  red  ray  is 
more  repulfive  than  the  violet,  we  perfeftly  reconcile  the  phenomenon  obferved  with  the  law 
of  reflection  acknowledged  to  prevail  in  plane  furfaces,  there  is  no  reafon  to  depart  from  it 
in  the  prefent  cafe. 

And  I  conclude,  from  all  that  has  been  faid,  that  the  hotnogeneous  rays  are  not  unequally 
rejlcxible  in  the  Broughamian  fenfe ;  or,  in  other  terms,  that  the  law  of  refleftion,  admitted 
by  Newton,  is  the  true  law  of  nature. 

( To  be  concluded  in  our  next.) 


On  the  Manufacture  of.  Beech  Oil^  by  Aaron  Hill^  and  other  Projeils  of  Improvements 

By  a  Correfpondent, 
Sir, 


w 


E  have  an  old  Englifli  proverb,  which  affirms,  that  it  is  much  eafier  to  aik  queftions  thaa 
to  anfwer  them.  I  have  lately  met  with  a  pamphlet,  which  has  tempted  me  to  propofe  a 
number  to  your  correfpondents ;  but  have  been  fomewhat  intimidated  by  the  above  con- 
fideration,  which  might,  perhaps,  prevent  your  favouring  me  with  their  infertion  in  your 
excellent  work.  It  has,  however,  occurred  to  me,  that  a  kind  of  middle  way  may  be  devifed^ 
to  render  the  bufinefs  more  fair  and  reafonable. — If  the  account  I  now  fend  you  fhould  be 
thought  to  contain  information  enough  to  render  it  acceptable  to  your  readers,  it  will  be  but 
fair  to  place  it  in  the  balance  againft  the  queftions  1  may  hope  to  have  rcfolved. 

The  pamphlet  I  allude  to,  is  jtaron  HilPs  Account  of  the  Rife  and  Progrefs  of  the  Beech 
Oil  Invention  (8vo.  112  pages),  which  bears  date  in  the  year  1715 :  and,  as  it  appears,  was 
given  away.  This  ingenious  man,  equally  known  for  his  works  of  imagination,  his  projcAs, 
and  the  tried  rectitude  of  bis  principles,  pafled  the  latter  part  of  an  active  life,  of  (ixty-five 
years,  in  a  ft  ate  of  poverty.  His  projcft  of  making  oil  from  the  beech-nut  was,  therefore, 
cither  unfuccefsful,  or,  what  is  more  probable,  it  failed  from  circumftances  dependant  either 
on  bimfelf  perfcnalJy,  or  thofe  who  were  engaged  with  him.  The  elucidation  of  this  object, 
which  is  of  no  fmall  importance  to  our  woollen  and  other  manufactures,  cannot  furely  be 
^foreign  to  the  purpofesof  your  Journal;  and  even  if  any  o  your  correfpondents  (hould  favour 
vs  with  biftbrical  fa<5ts,  tending  to  ihew  the  inutility  of  the  fcheme,  the  public  would]  no  doubt, 

VoXif  ,|II. — Aug  VST  1799.  H  b  receive 


230  Invention  of  the  Stocking-loom, 

receive  it  with  gratification  on  the  mere  inducement  of  curiolit '.  The  pamphlet  before-  m^ 
contains  alfo  notices  of  inventions  of  fome  ciiriofity  and  r.ppircnt  value,  though  related  almott: 
as  concifely  as  the  century  of  inventions  of  the  Marquis  of  Worcefter:  upon  the  whole,  they 
fliew  that  when  a  man  of  ability  leaves  the  beaten  p.th  of  the  current  afFairs  of  life,  topurfue 
the  remote  analogies  of  improvement,  new  refults  fpring  up  around  him  ;  to  the  practical 
accomplifliment  of  which  the  life  of  man  is  totally  inadequate,  and  in  the  purfuit  of  only  a 
few  of  which,  the  utmoft  endeavours  of  an  unfortunate  individual  may  be  exerted  without 
efFeft,  until  at  length  he  finks  under  the  ext  ?nt  and  variety  of  his  plans  and  occupations. 

To  your  difcrction,  fir,  I  fubmit  an  abridged  account  of  this  pamphlet.  If  from  the 
promife  of  utility  it  fhould  appear  fit  for  the  public  eye,  I  fhall  receive  pleafure  from  your  de- 
cifion  ;  if  the  contrary,  I  fhall  feel  no  pain  from  the  free  operation  of  a  power  which  I  think 
you  worthy  to  exercifc. 

The  treatife  confifts  of  a  general  introduflion  on  the  nature  and  advantages  of  new  in- 
ventions, and  the  prejudices  they  have  to  contend  with:  with  an  account  of  the  particular  in- 
vention which  forms  the  chief  fubjeft  of  the  addrefs.  The  author  complains  of  his  fufFerings 
from  thj  mifreprcfentations  of  ignorance  and  malice,  and  after  relating  the  ancient  ftory  of 
Thales,  the  Milefian,  who  enriched  himfclf  by  buying  up  oil  previous  to  a  fcarce  year  of  olives^ 
which  he  forefaw,  he  gives  an  account  of  the  difcovery  of  the  flocking  engine,  as  foUowS: 

<<  It  is  not  out  of  fome  mens'  remembrance,  that  a  young  gentleman  of  no  fortune,  a 
fiudent  in  Oxford,  fell  in  love  with  an  innkeeper's  daughter  of  that  town,  whofe  circum- 
ftances  were  very  narrow.  He  had  philofophy  enough  to  defpife  fuperfluous  wealth,  and 
judgment  to  forefee  the  neccfEty  of  a  competence,  but  love  was  headftrong,  and  too  hard  for 
reafon  ;  fo  that  after  a  year  or  two's  ineffeclual  delay,  they  bid  defiance  to  their  ftars,  and  had 
courage  enough  to  marry.  The  fcholar  gained  a  wife,  and  loft  a  fellowfhip :  the  only  fmail 
fubfiftance  he  before  depended  on." 

The  narrative  proceeds  to  acquaint  us,  that  the  father-in-law,  who  during  his  life-time 
defpifed  the  unproductive  acquifitions  of  his  daughter's  hufband,  died  miferably  poor,  and  left 
this  couple  in  a  ftate  of  extreme  indigence  >  their  whole  fupport  being  derived  from  the  in- 
duftry  of  the  wife  in  knitting  ftockings. 

In  this  fituation,  rendered  more  anxious  by  the  certainty  of  an  event  which  promifed  to  in- 
creafe  their  family,  and  to  fufpend  that  labour  which  afforded  their  fubfiflence,  the  hufband  could 
only  wafte  his  hours  between  his  books  and  his  fighs,  with  inefFe£lual  meditations  on  fchemes 
for  relief.  In  thefe  refie£lions,  his  eyes  were  often  involuntarily  fixed  on  the  motion  of  his 
wife's  fingers  at  her  work.  This  attention  was  at  laft  more  fteadily  diredted,  and  his  imagi- 
nation fet  to  work  on  the  enquiry,  whether  the  fame  operation  could  not  be  performed  by  ma- 
chinery. Both  parties  directed  their  ingenuity  to  this  refearch,  and  at  length  fucceeded  in 
making  a  flocking  loom,  to  their  own  great  relief  and  comfort,  and  lafting  benefit 
^  the  public. — ^.  Who  were  the  parties  here  fpoken  of? — The  author  then  mentions 
other  fpeculations,  and  the  numerous  inventions  which  diftinguifh  cultivated  nations; 
from  whence  he  deduces  the  evident  confequencc)  that   improvements  ought  to  be  en^ 

cotiraged» 


Various  Dlfcoverles  and  ProjeHs*  23^ 

couraged.  He  refers  to  Stow^  and  other  authors,  for  accounts  of  the  calumnies  and 
oppofition  which  were  made  to  the  projeft  of  the  New-River,  and  occafioned  the  ruin  of 
the  projeSor  of  that  ndble  work.  The  burning  of  bricks  with  pit-coal,  which  was  firft  done 
at  the  beginning  of  the  feventeenth  century ;  the  improvement  of  glafs,  introduced  by  the 
Duke  of  Buckingham  ;  the  projcdl  of  James  the  Firft,  to  introduce  the  growth  of  filk ;  the 

m 

eftablifhment  of  the  woollen  manufa£lure  from  Flanders  j  and  the  manufafturc  of  rape  oil,  are 
among  the  inftances  he  offers  in  favour  of  projedls :  and  to  thefe  he  adds  three  fpeculations 
of  difcoveries  of  his  own,  which  arc  little  more  than  hinted  at.  Speaking  of  tlie  firft,  he 
affirms,  that  there  is  a  common  vegetable,  almoft  the  growth  of  eVcry  hedge,  which  yields  a 
wax,  finer  than  that  ufed  for  candles,  and  at  an  cxpence  fo  inconfidcrable,  that  he  is  very  fure, 
that  in  the  pra6lice  of  the  thing,  a  pound  of  fuch  wax  candles  would  not  coft  three  halfpence. 
I  will  not  annex  a  formal  query  what  this  vegetable  may  be :  but  fimply  obferve,  that  an  en- 
quiry into  the  combuftibility  and  other  properties  of  vegetable  produvSs,  with  regard  to  this 
great  objedb  of  affording  light,  appears  to  deferve  the  attention  of  curious  men. 

Another  difcovery,  which  he  fays,  he  has  lately  beftowed  upon  an  honeft  gentleman,  is  that 
by  the  charge  of  a  fingle  penny,  cxclufive  of  the  price  of  coals,  he  can  produce  a  gallon  of 
aqua-vitae,  much  fitter  for  all  common  ufes  than  the  thrice-re*Slilied  fpirit  of  malt.  Query: 
What  is  the  date  of  the  general  pra<Sice  of  diftilling  fpirit  from  molafTes  ?  Much  earlier,  I 
fuppofe  than  this  period.  I  am  difpofed  to  think,  that  the  projeft  of  Aaron  Hill  may  have 
confifted  in  the  ufe  of  fome  faccharine  produft,  which  was  cheap,  but  not  plentiful;  and,  confe- 
qucntly,  could  not  be  procured  in  fufficient  quantity,  or  fuddenly  rofe  in  price  as  foon  as  a 
demand  was  felt. 

Another  objedl  of  information  is,  that  acorns,  dried  and  ground,  are  1  much  better  and 
cheaper  tanning  material  than  oak-bark,  and  that  it  is  ufed  iil  Italy,  and  all  over  the  Archipc- 
lao^o,  by  i\\Q  name  o(vcI.7ma»     Is  this  true  in  point  of  fa<St  ? 

The  laft  project:  is  a  fcheme  of  finance,  which  is  related,  or  alluded  to,  in  terms  of  the  higheft 
promlfe ;  but  as  there  is  no  hint  of  the  nature  of  the  plan,  and  as  political  arithmetic  is  a  fcience 
in  which  mi(\akes  are  not  only  poffible,  but  very  likely  to  be  made,  I  (hall  pafs  it  over  without 
further  remark. 

The  reft  of  the  book  contains  an  hifiory  of  the  difcovery  and  pradtice  of  the  aft  of  making 
oil  from  beech-maft.  The  author  firft  ftates,  that  the  raw  material  is  very  plentiful,  Und  that 
every  buftiel  is  found  to  yield  two  gallons  of  much  better  oil  than  that  of  olives,  called  Seville 
or  Gallipoli  oil.  He  informs  us,  that  he  made  the  difcovery  at  Naples,  in  1699 ;  but  being  at 
that  time  only  fifteen  years  of  age,  he  thought  no  more  of  it  till  17 12,  when  he  was  induced 
to  enquire  into  the  demand  for  oil,  by  the  foap  makers,  clothiers  and  others,  and  alfo  from  the 
dealers  and  the  entrances  at  the  Cuftom-houfe.  He  was  furprifed  at  the  extent  of  the  con* 
fumption,  and  immediately  undertook  to  afcertain  the  prafticability  of  procuring  the  beech- 
nut in  fufficient  plenty,  as  well  as  the  iburccs  from  which  he  might  derive  the  necefTary 
affiftance  for  eftablifhing  the  bufinefs.  He  met  with  no  encouragement  in  his  guarded 
applications  to  men  of  capital,  till  after  he  had  taken  out  a  patent,  at  which  period  he  found 

H  h  2  no 


232  JifanufaBure  of  Oil  from  thi  Beech^rmt. 

no  difficulty  in"  obtaining  a  fubfcription  of  twenty  thoulknd  pounds,  \rfiich  he  raifed  by 
engaging  to  grant  annuities  of  50  per  cent,  on  the  fum  fubfcribed.  He  afterwards  raifed  one 
hundred  thoufand  pounds,  upon  an  engagement  to  receive  beech-maft  from  the  fubfcribers,  at 
100  per  cent  profit  to  them,  for  two  years.  With  this  ftock,  he  proceeded  to  eftabli/h 
his  works  and  procure  orders  ;  the  latter  of  which,  amounted  to  upwards  of  two  and  twenty 
thoufand  tuns  of  oil,  at  40!.  a  tun,  or  near  a  million  fterling.  The  reports  concerning  the 
beech  muft  appear  to  (hew,  that  the  quantity  in  plentiful  years  is  prodigioufly  great ;  but  that 
this  happens  about  every  third  year.  It  alfo  appears  in  his  foreign  correfpondence,  not  only 
that  the  beech-nut  is  very  plentiful  on  the  continent,  but  that  its  application  to  the  pOrpofe  of 
manufafturing  oil,  had  been  known  and  pradlifed  for  near  a  century  in  the  northern  parts  of 
France.  One  of  his  correfpondents  points  out,  that  this  oil  is  preferred  by  many  to  the  bcft 
olive  oil;  that  it  had  long  before  been  mentioned  with  commendation  by  Evelyn,  in  his  Dif- 
courfe  on  Trees;  and  that  in  Bretagne,  the  millers. convert  the  beech-maft  into  oil,  for  the 
price  of  one  fous  per  bufliel,  and  the  oil-cake  which  is  ufed  for  feeding  cattle. 

After  this  mafs  of  apparently  good  evidence,  I  fhould  be  glad  to  know,  if  it  be  my  igno- 
*  ranee  only  which  leads  me  to  fuppofe  that  there  is  little,  if  any,  beech  oil  in  the  market  ? 
If  a  bufhel  of  beech-nuts  be  worth  lefs  than  fixpcnce,  and  will  afford,  by  mere  mechanical 
prefTure,  two  gallons  of  oil,  equal  in- quality,  or  even  much  worfe  than  olive  oil,  how  happens 
it  that  the  confumer  now  pays  hve  (hillings  a  gallon  for  whale  Qil  for  lamps,  and  flxteea 
{hillings  a  gallon  for  olive  oil,  in  flaiks  ? 

To  return  to  my  hiftory. — It  appears  on  the  whole,  that  Aaron  Hill  did  manufacElurc  this  oil, 
and  that  the  famples  were  highly  approved  by  the  Britilh  clothiers,  who  gave  him  large  orders ; 
that  the  year  immediately  fubfequent  to  the  formation  of  his  fubfcription  company,  proved  very 
unfavourable  for  the  beech-maft,  which  |was  lighter  and  lefs  oily  than  in  good  feafons;  that  his 
fubfcribers  became  alarmed  after  having  paid  their  [firft  inftalment,  which  was  fubjedl  to 
forfeiture  in  cafe  of  failure  in  the  laft  payment;  that  the  patentee,  inftead  of  infifting  upon 
this  bargain,  had  the  honourable  fpirit  to  offer  them  a  repayment  of  their  money,  with  a 
profit  of  twenty-five  per  cent.—  that  this  offer  was  accepted,  and  a^^ually  performed  to  the 
whole  of  the  fecond  clafs  of  fubfcribers,  and  one-third  part  of  the  original  annuitants;  the 
remainder,  to  the  amount  of  about  thirteen  thoufand  pounds,  choofing  to  retain  their  annuities. 
Here  I  muft  remark,  that  the  fcheme  feems  to  have  realized  fome  conGderable  profit, 
fince  the  advantage  allowed  to  the  fubfcribers  over  and  above  their  money  returned, 
muft  have  been  near  eight  thoufand  pounds;  befides  which,  there  were  undoubtedly  many  ex- 
pences  and  difburfemcnts  made.  Is  it  to  be  fiippofed,  that  thefe  wae  all  paid  out  of  the 
thirteen  thoufand  pounds  which  were  not  withdrawn  ? 

The  obje6t  of  the  pamphlet  was  to  circulate  propofals  for  eftablifhing  a  new  company,  to 
which  the  whole  patent,  fubje£l  to  the  annuities,  was  to  be  af&gned  for  twenty-five  thoufand 
guineas,  and  one-twentieth  part  of  the  profits,  under  certain  general  regulations,  cxprefled  in  a 
deed,  inr oiled  in  Chancery  for  that  purpofe.  The  {hares  were  five  thoufand,  at  forty  pounds 
a-piece :  befides  the  premium  of  five  guineas  on  each  ihare.  What  became  of  it  afterwards,  I 
know  not.  I  remain,  Sir, 

LnntUfiy  Jufy  6|  179^  Your  conftant  reader,  X.  X« 


/ 


Y 


On  thi  Con/hu5lm  of  a  Balana.^^ScientiJic  News,  tifc;  ajj 

XL 

Letter  from  Mr.  TMOUGHrON  refpe5ttnga  Balance  of  his  Conjlruclkn. 

To  Mr.  Nicholson. 

SlR>  Ficet-ftrcct,  Julf  9,  17^^. 


OU  will  not,  I  apprehend,  think  yourfelf  at  all  obliged  to  the  perfon  who  communicated 
die  information  expreffed  in  your  note,  page  loi,  vol.  III.  of  your  Journal,  when  I  alTure 
you,  that  the  beam  which  I  made  for  Sir  Geo.  Shuckburgh  Evelyn,  had  circular  rings 
fattened  infide  the  cones  j  without  which  neceffary  precaution,  it  would  moft  certainly  have 
been  good  for  nothing.  The  other  diflFerence  is  moft  trifling ;  however,  I  will  tell  you,  that 
the  ftnfibility  of  his  balance  is  not  perceptibly  diminifhed,  when  the  beam  deviates  three 
degrees  from  the  horiaontJ  pofition ;  and  that  the  crytlal  planes  wt^r;i  fjt  and  levelled  within 
half  that  number  of  minutes,  by  other  means  than  thof';  pointed  out  in  your  note;  and  your 
informant  may,  perhaps,  be  able  to  (hew  the  mighty  Jifflrcncs  between  the  axis  being  in- 
clined to  the  planes,  and  thofe  planes  being  inclined  t  >  the  axis.  It  is  moft  true,  that 
the  conical  form  of  this  beam  is  borrowed  from  that  of  the  Royal  Society:  but  the  former 
being  defigned  to  weigh  twetv  e  times  as  much  as  the  latter,  I  (aw  ample  caufe,  in  other 
refpecSls,  to  deviate  from  that  model. 

After  all,  thofe  who  are  acquainted  with  the  fimple  principles  of  the  balance,  and  eafe  of 
conftrufting  it,  will  hardly  think  the  maker  of  either  inftrument  in  queftion,  entitled  to  any 
higher  credit  than  what  is  due  t^  good  workmanfliip :  and  more  cipecially  fo,  was  it  generally 
known,  that  there  is  an  inftrument  in  the  aflay-office,  Tower  of  London,  and  which  was 
ufed  there  by  Sir  I(a;ic  Newton,  when  he  was  affay-mafter,  to  which  the  Royal  Society's 
^balance  bears  full  as  great  an  affinity  both  in  form  and  properties^  as  Sir  George's  does  to 
the  latter. 

I  am,  fir,  relying  on  your  candour,  and  diankful  for  the  information  and  pleafure  which  I 
receive  from  the  conftar>t  perufal  of  your  Journal, 

Your  moft  humble  fervant, 

'     EDWARD  TROUGHTON. 


A: 


SCIENTIFIC  NEWS,  ACCOUNTS  OF  BOOKS,  b^c. 


.N  important  work  of  Mr.  Kirvtran  is  now  in  the  prefs,  and  nearly  ready  for  publi- 
cation, under  the  title  of  ^  Geological  Eflfays ;.  comprehending,  the  origin  and  conftitution  o£' 
mountains,  feas,  lakes,  coal-mines,  beds  of  (alt,  and  ofmetallk:  ores,  and  evincing  the  accuracy 
of  the  details  of  the  formation  of  the  earth  and  of  the  deluge,  delivered  by  Mofes,  from  the 
laws  of  nature,  and  the  appearances  it  esdubits  in  its  prefcnt  ftate»    By  Richard  Kirwafi). 

Efqt.  FJR.S.'t 

Propo(aI» 


/. 


^34  '         Scientific  News,  ^c. 

Propo(als  have  been  circulated  by  Mr.  A.  Q.  Buee,  a  French  clergyman  at  Bathi  for 
publifhing,  by  fubfcription,  a  work,  entided,  Recherche s  Math^matiques  fur  la  Texture 
intime  des  Corps;  or,  Mathematical  Enquiries  concerning  the  intimate  Texture  of  Bodies ; 
of  which  he  is  the  author.  It  will  be  printed  on  fine  paper,  and  illuftrated  with 
fix  copperplates*  The  manufcript  is  in  the  hands*  of  the  printer,  and  the  work  will  be 
put  to  prefs  as  foon  as  one  hundred  and  fifty  fubfcribers  (hall  be  obtained  at  half  a  guinea  each: 
the  price  will  be  greater  to  non-fubfcribers.  Meffrs.  Dulau  and  Co#  Cox,  White,  and 
Phillips,  are  authorifcd  to  receive  fubfcriptions. 

The  author  of  the  above  treatife  has  drawn  up  and  printed  (in  French)  an  outline  of  its 
contents,  in  twenty-three  oftavo  pages.  From  the  perufal  of  this,  I  gather  that  it  is  a  work 
of  confiderable  novelty  and  importance.  Whether  any  philofopher  has  before  undertaken  to 
folve  the  phenomena  of  nature,  by  the  univerfal  combination  of  projeftile  forces  with  the 
attr%£live  power,  in  the  particles  of  matter,  is  to  me  uiiknown ;  and  it  is  evidently  impoffible  for 
me  to  fpeak  of  the  manner  in  which  he  has  treated  this  curious  fubje£l.  I  am  aware  alfo,  of  the 
diiliculties  and  probability  of  miflake  attendant  on  an  endeavour  to  give  an  outline  of  an 
outline.  In  fa£):,  there  muft  be  a  large  part  of  the  author's  (ketch  which  will  be  unintelligible9 
without  reference  to  the  treatife  itfclf ;  notwithftanding  which^confiderations,  I  am  perfuaded 
that  my  readers  will  be  pleafcd  to  know  fomething  more  of  this  objeft. 

The  author  begins  his  (ketch,  by  dating  that  we  are  acquainted  with  two  fafls  concerning  the 
intimate  texture  of  bodies :  namely,  their  cryftallization,  which  (hews  that  their  elements  are 
difpofed  in  right  lines;  and  their  dilatation  by  heat,  which  (hews  that  thofe  elements  are 
not  in  contadl.  From  the  two  grand  laws  of  attraction,  following  the  inverfe  ratio  of  the 
fquares  of  the  diflances,  and  that  of  inertia,  the  mutual  a£lion  of  the  elerpents  upon  each 
other  may  be  expreffed  by  an  algebraic  equation :  this  may  be  called  the  equation  of  the 
material  univerfe.  The  author  could  not  enter  upon  it  in  his  (ketch,  and  therefore  only  ob- 
fcrves,  that,  according  to  this  equation,  each  element  defcribes  a  line,  which  if  there  were 
but  three  elements  prefent,  would  be  the  fame  as  is  well  known  in  phyflcal  aftronomy  in  the 
problem  of  the  three  bodies^  but  univerfally  is  the  refult  of  as  many  fmall  arcs  of  conic  fe6lions 
as  there  are  other  elements. 

As  fome  of  the  conic  fe6li6ns  return  into  themfelves,  and  others  do  not,  the  elements  will 
be  fome  planetary,  and  fome  cometary  ;  the  latter  being  diftiiigui(bed  from  the  former,  by  a 
greater  initial  velocity.  But  the  cometary  elements  ariving  in. the  vicinity  of  other  elements 
are  dillurbed,  and  made  to  circulate  round  a  certain  number  of  elements ;  the  planetary 
elements  ofcilbte. 

Abfolute  repofe  or  equilibrium  has,  therefore,  no  placSc  in  bodies,  except  eventually  and  for 
minute  portions  of  time ;  but  apparent  repofe  is  produced  by  the  rapidity  of  ofcillation  in  the 
planetary  elements,  and  the  conftancy  of  their  greatcft  and  leaft  diftances ;  this  apparent  re- 
pofe implies  fymmetrical  arrangement,  and  the  great  agents  of  this  fymmetry  are  the  cometary 
dements; 

The  doftrine  of  fymmetry  is  applied  to  the  explanation  of  chemical  fails.  Four  kinds  of 
Aggregation  include  all  the  poffible  fyftcms  of  elements  :  i  •  Igniform  aggregations  \  containing 

on\7 


Scuntijic  NrwSy  tsfe.  535 

only  cometary  elements:    2.  Aeriform  j  containing  more  comets  than  planets :  3.  Liquid!- 
form ;    in  which  the  planets  exceed  the  comets :    4.  Solidiformj   containing  planets  only. 
Thefe  ftates  may  not,  perhaps,  exift  purely  and  diftinft  from  each  other  in  nature.     Another 
fifth  ftatc  is,  that  in  which  no  aggregation  takes  place.     The  latter  cometary  elements  are  the 
particles  of  light,  of  which  the  colours,   the  reflexion,  refra£iion,  difFraftion,   abforption, 
double  refraftion,  the  Newtonian  fits,  6cc.  are  explained  by  analyfis ;  together  with  thofc 
refults,  in  which  light  is  faid  to  enter  into  combination.     The  formulae,  which  relate  to  the 
igneous  aggregation,    are  applied  to   caloric,  eledlrlcity,    and   magnetifm.      The  aeriform 
aggregation  exhibits  the  phenomena  of  fluidity,  compreflibility,  hydroftatics,  and  found  ;  and 
under  the  article  of  the  folidiform  aggregations,  fomq  obfervations  arc  made  refpedling  im- 
pulfe,  claflicity,    mechanical  divifion,  and  re-union :    and  the  caufcs  which  produce  cryftal--^ 
lization,  vegetation,  and  animalization.     When  two  diftinfi:  bodies  approach  each  other  as 
nearly  as  poflible,  without  ceafing  to  be  diftin^  and  by  the  influence  of  the  elements  of 
the  one  upon  the  elements  of  the  other,  their  centres  of  gravity   acquire  a  new  motion ; 
this  operation  is   called   impulfe.      Mechanical  divifion  is  the  feparation  of  the    parts    of 
a  body,  by  contrary  impultlons  given  to  thofe  parts  :    if  the  diredl  contrary  operation  could 
be  performed,  mechanical  union  would  take  place ;    this  is  performed  to  a  certain  extent 
when  polifhed  furfaces  adhere  by  application  to  each  other. 

With  regard  to  the  other  dodlrines  of  cry  flail  ization^  vegetation,  and  animalizadon,  in 
which,  I  prefume,  there  muft  be  fome  principles  afliimed  as  data,  which  may  require  farther 
experiment;  it^would  anfwer  no  ufeful  purpofe  to  enumerate  the  refults.  For  the  developement 
of  thefe,  we  muft  wait  till  the  work  ftiall  appear. 


Death  of  Galvani. 


The  celebrated  philofopher,  Galvani,  died  lately  at  Bologna,  at  the  age  of  fifty-five.  His 
name  has  been  given  to  the  difcovery  of  the  influence  of  the  conta£t  of  two  metals  on  the 
animal  economy.  The  circumftance  which  occafioned  this  difcovery,  is  not,  perhaps,  generally 
known.  The  wife  of  Galvani  took  foup  of  frogs  on  account  of  her  health ;  her  huft>andy 
who  was  much  attached  to  her,  had  fltinned  Several  frogs,  and  on  touching  them  by  chance> 
he  unintentionally  made  a  communication,  which  produced  the  fingular  phenomenon,  fince 
known  by  the  name  of  Galvanifm.  The  account  to  be  publiflied  by  the  commiflTaries  of  the 
inftitute^  and  the  memoir  of  Earon  Humboldt,  in  the  Journal  de  Phyfique,  for  the  month  of 
Prarial^an  6,  give  an  ample  account  of  this  curious  difcovery.  Dr»  Aldini,  nephew  and  co- 
operator  with  Galvani,  is  employed  on  a  continuation  of  experiments  calculated  to  elucidate 

diis  pbtnomenon  ftiU  fiuther*^ 

talande,  in  the  Magaz,  Encycl.  V.  55  r» 


2^6  Scientijic  News,  isfc. 

On  the  Acoujiic  Experiments  of  Chladni  and  Jacquin. 
M.  E.  Perrolc,  fome  of  whofe  experiments  on  found  are  infcrted  in  our  Journal,  I.  411. 
has  written  to  Citizen  Delametherie  ♦  a  letteT,  in  which  he  cxpreffes  his  doubts  refpefting 
the  truth  or  accuracy  of  the  experiments  of  Chladni  and  Jacquin,  announced  at  p.  43  of  our 
prcfent  volume.  His  arguments  are,  in  (hort,  that  Dr.  Prieftley,  who  made  experiments  with 
a  bell  under  a  jar,  fuccefEvely  filled  with  the  fevcral  gafes,  as  well  as  himfelf,  did  not  perceive  any 
fuch  difference  of  tone.  He  candidly  takes  notice,  that  thefe  laft  experiments  are  different  in  their 
circumftances  from  thofe,  in  which  a  flute  was  ufed ;  but  docs  not  fecm  difpofed  to  condder 
the  difference  as  of  much  importance.  On  this  head  it  may  be  fufficient  to  remark,  that  the 
difference,  if  theoretically  confidcred,  is  indeed  very  great :  and  that  the  praftical  refults  may 
moll  conveniently  be  eftabliflicd,  or  refuted,  by  die  teft  of  experiment. 


New  fulminating  Mercury, 
Mr.  Edward  Howard  has-  lately  difcovered  a  fulminating  mercury,  tl\e  preparation  of 
which  is  in  no  refpeft  fimilar  to  thofe  defcribed  by  Bayen  or  any  other  chemift.     Two 
grains  laid  on  an  anvil  and  ftruck  with  a  hammer  (both  cold),  exploded  with  a  dunning 
noife,  which  was  felt  on  the  top  of  the  head,  and  produced  a  flight  temporary  deafnefs. 
Lefs  than  one-fourth  of  that  quantity  gave  a  report  like  the  found  of  a  whip.     Mr.  Howard 
(hewed  me  a  powder-proof  and  the  breech  of  a  mufquet,  both  of  which  had  been  burft 
by  this  powder.     The  powder-proof  confifted  of  a  brafs  gun,  originally  of  the  bore  of  one- 
fifth  of  an  inch  diameter,  and  near  a  quarter  of  an  inch  thick,  except  where  a  fpring  had 
been  let  in  to  the  diminution  of  half  tlie  thicknefs.     This  chamber,  which  was  one  inch 
and  quarter  long,  could  contain  eleven  grains  of  fine  gun-powder,  and  was  filled  with  the 
mercurial  compound.     The  explofion  tore  tlie  barrel  open  by  a  longitudinal  crack  at  top, 
the  extreme  parts  of  which  were  onc-fifth  of  an  inch  afunder.     The  bore  was  enlarged, 
tapering  froni  the  breech  to  the  muzzle,  where  its  fmalleft  diameter  was  more  than  twice 
its  original  meafure.     A  neat  indentation  was  made  on  the  face  of  the  index  to  the  depth 
of  near  one-tenth  of  an  incji,  and  it  was  fl:ruck  off  from  the  wheel  to  which  it  was  intended 
to  give  motion. — ^Tlie  other  piece  or  breech  was  of  the  beft  folid  forged  iron.     It  had  a  fmall 
chamber  of  0.4  inch  diameter,  and  the  fame  thicknefs  of  metal,  namely  0.4  inch  all  round. 
The  explofion  rent  it  afunder  by  a  crack  paffmg  through  the  touch*hole,  which  was  protrud- 
ed and  furrounded  with  radial  cracks :  and  each  of  the  pieces  was  flawed  and  cracked 
crofs-wife. — Hence  it  fliould  appear  that  the  force  (or  at  leaft  the  rapidity  of  combuftion)  of 
diis  powder  is  too  great  for  fire-arms  5  though  it  may  probably  be  of  value  in  mining.— 
When  a  train  of  about  four  inches  long  was  fired  the  time  of  fucccilive  combufLion  could 
not  be  meafured  ;  but  a  very  flender  train  of  twelve  inches  fecmed  to  employ  about  half  a 
fecond.     Gujipowder  pulverized  and  burned  in  the  fame  circumftances  could  not  continue 
its  fire  J  but  when  the  quantity  was  greatly  increafed,  the  train  burned  in  one  fecond  and  a 
quarter,  with  a  noicc  much  lefs  (harp  than  that  of  die  detonating  mercury.     It  docs  not  ex- 
plode nor  undergo  any  change  by  the  heat  of  a  water  bath ;  but  when  a  particle  was  laid  on 
a  thin  bar  of  fteel,  and  heat  applied  at  one  end,  the  powder  exploded  juft  before  the  firft 
ftraw^  colour  reached  it    I  eftimate  this  to  be  fomewhat  higher  tha^  400^.  of  Fahreo* 
bcit^ 

♦  JouTiial  de  Pjyfiquc,  V.  455. 


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II    ■    ■■!  |fipi^ifcw^inw»»i^i— —^i— *<^^WlW^w^i»^«^—i 1— ^P— —^^^^w^— ^^^'™«— ^^— '^»*^         ■»« 


JOURNAL 


O  F 


NATURAL    PHILOSOPHY,    CHEMISTRY, 


AND 


THE   ARTS. 


SE  PTE  MBER    1799. 


ARTICLE    I. 

A  arcumjlantial  Defcrlptton  of  the  Method  of  cultivating  the  White  Beet  (Runhlruhe)^  in 
order  to  obtain  the  greatefl  Quantity  of  Saccharine  Matter  ^  and  to  prepare  it  for  the  Afanu* 
failure  of  Sugars     By  F.  C.  AcHARD^  Director  of  the  Phyfical  Clafs  in  the  Royal  Academy 
of  Sciences  ^. 

J.  N  the  courfe  of  feveral  years  paft  I  have  made  experiments  to  afcertain  how  far  various  na- 
tive plants  might  be  Ht  for  making  fugar.  In  thefe  enquiries  I  had  the  opportunity  of  obfenr- 
ing,  that  the  quantity  of  faccharine  matter,  and  its  proportion  to  the  other  conftituent  parts  of 
the  fame  fpecies  of  plants,  may  be  increafcd  or  diminifhed  by  the  manner  of  cultivation* 

2.  Among  the  various  plants  which  I  examined,  for  the  purpofe  of  niaking  Qigac  in  thilf 
country,  I  paid  particular  attention  to  the  feveral  fpecies  of  i^/^  vulgaris  Zr/;;w<rx^'brieof  whichi 
peculiarly  proper  for  manufafturing  fugar,  is  known  to  the  cconomift  in  this  country  by  th^' 
name  of  runkelriibefy  and  to  the  gardener  more  cfpecially  by  the  name  of  mangoldriibc*     On 

*  Tranflated  from  '<  Ausf ubrlichc  Befchreibung  der  Mcthodc  ntcb  welcher  bei  dcr  Kulturder  Runckiiel- 
ruhe,"  &c.  von  F.  C.  Acliard,  Director,  &c.  Berlin,  1799.     O£ttvo,  63  pages.  -  '< 

'f  At  nobouoift  has  given  the  charafters  of  tbis  Runkelriibe,  ^r^i/^affff  defcribes  it  in  the  foUowjog  iiun«« 
ner:  Beta  aUiJftma^f.oYibui  ternn*vcl  quaternhy  foliolis  eaiycis  iftermilus,  cariHO/is,  caule  crajjijfimo  fafiiato^  radicjL 
maxima^  rubro  et  albo  i^tus  njar'trgata^  folmmaximii  rubeHtrbus. '^liotc  of  the  tranflator,  from  jtfoJdecbeH*s  trca* 
tile  on  the  culture  of  this  plant. 

Vox-  IIL— September  1799*  li     '  comparing 


238  On  tbi  CuHuri  9/ the  Biitf 

comparing  the  feveral  Tariettet  of  this  kind  of  plants,  I  wu  convinced,  diat  tfie  ptrticalar 
variety,  polTefled  of  a  long  anical  rooU  red  rtnd^  and  the  interior  part  xobite^  was  die  moft 
abundant  in  fugar,  and  that  the  (acdiarine  contents  of  this  vari^y  of  the  beta  vulgaris^  called 
runkelriibe,  may  be  greatly  augmented  or  diminilhedi  according  to  the  various  methods  of 
cultivating  it. 

3.  Having  treated  this  root  by  various  methods  of  culture,  I  obtained  fugar  from  it,  with 
more  or  lefs  profit;  in  fome  inftances  with  lo6y  or  even  no  fugar  at  all ;  but  frequendy  a  mere 
cxtradl,  in  the  form  of  a  pulp,  fmelling  like  turnips ^  in  which,  from  the  excefs  of  extradlive 
matter^  no  fugar  could  cryftallize,  unlefs  fome  expeniivc  artificial  expedients,  not  applicable 
in  the  large  way,  had  been  employed.  Thefe  obfervations  have  convinced  me  of  the  great 
influence  of  cultivation  on  the  faccharine  contents;  and  I  fpared  no  induftry  in  order  to  dif^^^ 
cover  the  management  by  which  this  root  might  be  cuhivated  of  the  greateft  ridinefs  in 
fugar.  I  have  not  only  raifed  them  under  various  iituations  on  my  eftate,  Fremb  BuekhJi%^ 
but  have  procured  fuch  roots  from  various  other  territories,  as  firom  MagMurgb^  Hm&er*^ 

Jladty  Brunfwick^  Blankcnburg^  Gecfar^  and  Nauen^  with  accounts  of  the  methods  by  which 
they  were  cultivated 

4.  I  then  compared  the  refults  of  the  experiments  which  I  had  inftituted  for  the  purpofe 
of  obtaining  fugar,  pardy  from  roots  of  my  own  in  different  circumftances  of  growdi,  and 
partly  from  thofe  of'  other  foils,  which  wpre  likewife  differendy  culdvated. — By  this  means  I 
have  found  that  the  faccharine  matter  of  this  root  may  be  confiderably  increafed,  and  the  ex- 
tra^ive  n^atter  confiderably  dhniniflied.  The  conditions  are :  (a)  That  it  (hould  be  culti* 
vated  in  a  rich  foil,  which  will  be  beft  adapted  to  it,  if  it  be  rather  compaft. 

(b)  The  feed  is  not  to  |)e  fown  in  one  bed,  and  the  plants  afterwards  removed  to  anodier^ 

as  is  commonly  done  i  but,  on  the  contrary,  they  mufl  be  fuffered  to  ripen  on  die  fyot  in 
which  they  germinate  from  their  (eedis. 

(c)  The«roots  muft  not  be  too  diftant  from  each  other.  In  the  beft  foil,  their  mutual 
diftance  iliould  be  one  foot :  in  a  poorer  foil,  ftill  nearer^^ — ^nine  inches  at  moft. 

(d)  After  fliey  have  fprouted,  they  muft  be  cleared  of  the  weeds,  either  by  the  hoe  or  by 
^llii^:  taking  care,  when  the  hoe  is  ufed,  that  the  earth  be  not  remov^  from  the  phuit^ 
but  ratheri  though  (lightly,  brought  neares  to  it.  This  is  not  neceflary,  when  the  weed& 
are  pulled  up*  It  is  ufual  to  remove  the  earth  from  the  plant,  when  it  is  cultivated  to  forve 
as  food  for  catde^  for  its  ppper  part  is,  by  this  management,  gready  enlarged,  and  it  acquires 
a  greater  mafs  in  the  whole:  bu;  fuch  management  is  highly  detrimental  to  die  runkekSbe 
intended  for  making  fugar* 

..  (e)  The  leaves  muft  not  be  taken  off  from  the  f\^U  as  is  the  cuftom,  for  the  purpofe 
of  feeding  cattle.  This  treatment  diminiOies  the  ftcdiarifle  matter  of  the  root,  at  the  fiune 
time.diac  it  increafes  its  mucilaginous,  earthy,  and  fari;2a^eous  parts;  and,  confequendy,  ia 
fcry  injurious  to  the  quality  of  die  root,  if  approprnted  for  making  /l^^^- 

5.  On  dieft  five  politions,  which  are  grounded  oh  repeated  experiments"  ami  ci^jvationf, 
I  tan  witbjufticcand  imdiinftfti  indU^imritbrefpeft  to  the  manufaOory  pf  native  fi«^  tt 

earned 


fir  thi  Purpdfe  of  affording  Sugar.  239 

carried  on  with  profit  from  the  n^nkelriibe,  every  thing  depends  on  its  proper  culture.  For 
k  is  bv  this  means  only  that  the  ihcreafe  of  its  faccharine  contents  can  be  promoted  \  and  it  is 
only  from  die  quantity  of  ihis  laft  produ(Sl  that  fugar  can  be  made  with  profit  from  that  root 
in  the  large  way.  ^ 

That  this  rcot  contains  fugar,  has  been  long  fince  proved  by  my  celebrated  predecefTor 
in  the  Royal  Academy  of  Sciences,  the  late  Dire<5lor  Margraaf.  But  it  was  then  unknown 
and  unfufpeded  that  it  could  be  obtained  from  it  in  the  large  way,  and  fo  cheap  as  2  grojhes 
(about  three  pence  Englifh)  for  the  pound  of  cryftalline  raw  (iigar^and  in  fome  trials  dill  cheaper, 
as  I  have  demonftrated  to  be  praAicable,  by  the  experiments  made  in  the  prefence  of  the 
committee,  feleded  for  that  purpoTe,  by  the  king's  conunand.  This  refult  is  different  from 
all  trials  hitherto  made  in  this  repe£l,  by  the  moil  able  chemifts.  The  caufe  is  fimply,  that 
the  great  influence  which  the  culture  of  the  runkelriibe  has,  with  regard  to  the  increafe  of 
its  fugar,  has  not  been  fufpeded,  and  that  the  different  modifications  of  that  culture  were 
uniuiown  t  though,  in  bStj  the  quantity  of  faccharine  matter  may,  on  the  one  hand,  be  highly 
augmented,  while,  on  the  other  hand,  the  proportion  of  thofc  conflitucnt  parts,  which  pre- 
heat the  feparation  of  the  fugar,  are  greatly  diminiflied. 

6.  From  the  mediod  before  defcribed,  of  producing  the  runkelriibe  abundant  in  fugar  by 
means  of  a  proper  cultivation,  and  from  my  other  obfervations  on  the  moft  profitable  ma* 
sagement  of  this  root,  the  following  inftru£lions  may  be  taken  for  its  cultivation : 

A  foil  upon  which  wheat  has  grown  is  to  be  chofen,  and  kept  in  good  condition*  A  low 
fituation,  not  expofed  to  great  or  lafling  drought,  yet  without  being  moid  or  fwampy,  is  to 
be  preferred*  It  is  better  if  manured  the  year  before  than  recently;  which,  however,  muft 
be  done,  if  the  former  manuring  has  been  omitted.  This  ground  is  to  be  ploughed  thrice  over, 
and  as  deep  as  the  nature  of  the  foil  will  admit*  It  ^s  alfo  very  advantageous  to  perform,  if 
foffible,  the  firft  tillage  in  Autumn.  Immediately  after  the  third  ploughing,  which  fhould 
be  done  in  the  middle  of  April,  or,  at  latefl,  about  the  middle  of  May,  the  ground  is  to  be 
Anoothed  by  the  harrow,  as  much  as  pofltble ;  and  by  means  of  a  rake,  whofo  teeth  are  difhuit 
A-om  9  to  12  inches,  lines  are  to  be  traced  along  the  forface,  and  by  drawing  the  rake  in 
lines  acrofs  tfaeTe  the  ground  becomes  divided  into  fquares,  meafured  by  the  diftance  of  the 
cake's  teechf* 

*  In  this  computation  the  hbourcr's  wages  arc  taken  at  8  grofbet  per  day,  and  the  fuel  at  the  price  of  the 
royal  Berlin  wood-market.  Befides,  in  mj  prefent  experiments,  a  circumftance  occurs  which  greatly  en- 
hances the  eipcnces  of  particular  operations ;  namely,  that  the  proceflcs  cannot  be  concatenated^  or  connected 
ivith  each  other.  Notwithftanding  this,  the  pound  of  raw  fu|;ar  will  coft,  at  the  higheft,  only  2  groihcs,  and 
by  fome  methods  fiill  lefs ;  bccaufe  the  manufacturer  will  not  pay  the  day  wages  at  higheft  rate,  nor  chufe 
Berlin,  the  deareft  {ilace,  for  ef^ablilhing  his  manufaftory.  Thus,  alfo,  he  will  not  buy  his  fuel  at  the  greateft 
or  retail  price,  but  will  take  all  the  advantages  refulting  from  the  connection  of  the  fcveral  proceflcs,  which 
^  not  take  place  in  Angle  trials,  as  they  muft  in  carrying  on  the  bufinefs  at  large. 

f  As  I  hare  not  fpoken  with  precifion  of  this  diftance,  but  have  only  given  it  fiiam  9  to  12  inches,  1  mdl 
hat  remark,  that  it  muft  be  regulated  by  the  goodnefs  and  richncfs  of  the  foil.  On  the  beft  groun.i  the 
4diftaocc  Qf  I  foot  it  moft  fuitable :  on  a  leaner  foil,  lefs  manured^  it  is  better  to  contract  it  to  ^  inche«. 

I  i  2  7-  Into 


a  40  On  she  Culture  of  tht  Beet^ 

7.  Into  each  interfecSling  point  of  the  lines  delineated  by  the  rake,  one  Cngic  feed  eapfule^ 
if  you  are  convinced  of  its  good  quality,  is  to  be  lluclc  in.  But  if  not^  then  two  fudr  capfules 
are  to  be  put  in;  and,  in  either  cafe,  to  the  depth  of  an  inch.  This  operation  may  be  done 
by  children,  or  inferior  labourers.  When  the  plants  have  germinated  out  of  the  ground,  and  fsx 
or  eight  leaves  are  formed,  the  weeds  muft  be  deftroyed  or  pulled  up;  but,  as  I  have  already 
obferved,  the  removal  of  the  earth  from  the  plant  is  to  be  very  carefully  avoided.  It.anfwers 
better  to  pufh  the  earth  nearer  to  the  plant,  though  this  may  be  negle&ed  without  any  bad 
confequence.  At  this  period  of  the  culture  there  is  another  operation  to  be  performed.  If 
the  plants  be  too  much  accumulated  on  a  particular  fpot,  which  is  often  the  cafe  when  very 
good  feed  has  been  ufed,  becaufe  one  capfule  contains  feveral  feed  grains,  and  produces  more 
plants  than  one  on  the  fame  fpot;  in  this  cafe  the  fuperabundant  plants  are  to  be  ptiUed  out.' 

8.  There  is  no  occafion  for  this  operation^  if  the  feed  has  not  been  quite  frelh,  or  not 
quite  ripe.  But  in  cafe  fome  empty  places  (hould  be  found,  where  nothing  has  grown  h|i, 
two  fre(h  grains  (hould  be  inferted.  After  the  ground  has  be^n  once  cleared  of  die  weedf» 
the  plants  grow  up  (6  fpeedily«  that  their  leaves  foon  completely  cover  the  ground;  and  thus 
abfolutely,  prevent  the  growing  of  any  more  weeds*  In  confequence  of  this,  and  to  the  great 
advantage  to  the  farmer,,  an  acre  of  ground  cultivated  with  runkelrube,  occafions  no  more 
trouble  till  the  time  of  gathering:  which  circumftance  greatly  facilitates  dieir  cultivatiott; 
becaufe  the  time  of  the  cultivator,  who  is  Utifxi  buCed  in  his  corn  harveft,  is  not  required -to 
be  at  all  employed  on  this  objeA.  For  the  gathering  of  thefe  roots  begins  only  towards  the 
end  of  September,  and  maj^^  be  continued  to  the  end  of  October,  if  no  early  froft  fets  in* 

9*  At  this  gathering  nothing  particularly  remarkable  occurs,  except  that  the  root  muft.be 
as  little  injured  as  poffible;  partly  to  prevent  the  lofs  of  its  juice,  and  partly  to  prevent  the 
decay  to  which  the  wounded  parts  are  more  expofed  than  the  found  ones.  The  verdure  muft 
then  be  cut  off,  in  fuch  a  manner,  that  the  heart  may  be  alfo  feparated,  in  order  to  prevent 
the  germination  of  the  root.<.  Too  much  (hould  not,  however,  be  lopped  off  the  head;  bc^ 
caufe  the  juice  would,  in.  that  cafe,  too  plentifully  exfude.  Thefe  leaves  and  hearts  are 
exceedingly  valuable  to  the  farmer  at  this  time,  when  other  green  food  for  his  cattle  is 
wanting. 

10.  The  roots  may  be  kept  for  ufe  in  ditches  dug  in  the  earth,  where  the  depth,  the  dry- 
nefs,  and  the  loofe  nature  of  the  foil,  admits  of  it.  Where  this  is  not  pradicable,  on  account  of 
the  moifture  and  firmnefs  of  the  foil,  they  may  be  preferved  and  fecured  againft  the  froft  in 
cellars.  But  the  heart  muft  not  be  taken  out  nor  injured  in  fuch  roots  as  are  kept  during 
the  winter,  in  order  to  obtain  feed  from  them  by  tranfolantation  in  the  fpring.  The  leaves 
are  merely  to  be  broken  off.  The  roots  muft  be  well  covered  during  winter,  and  (heltcrecL 
againft  froft.  In  general,  in  the  production  of  the  feed  from  the  runkelrube,  the  £uiie 
method  is  to  be  ufed  as  with  other  biennial  roots  and  fpecies  of  cole.  As  this  procedure  is 
known  to  every  economift  and  gardener,  I  (hall  lofe  no  time  by  defcribing  it. 

II.  When  large  diftrids  of  ground  are  to  be  cultivated  with  this  plant,  the  feed  capfules 
cannot,  for  want  of  time,  be  fingly  put  into  the  groundt    The  feed  muft,  therefore^  beiciwn 

lvith 


With  the  gfeat^ft  pcJffible  unifiutri^y..  Tbe  Magdeburg*  atre  will  require  from  3  to  4  pounds 
of  feed,  according  to  the  quality  6f  the  foil.  If  the  fowing  has  been  well  performed,  the  plants 
will  be  diftant  9  inches,  or  a  foot  at  mofl.— In  cafe  the  roots  grow  nearer  to  each  other, 
^hey  do  not  contain  Icfs  fug^r  on  this  account,  but  they  remain  fmall.  If  too  far  afunder, 
they  grow  larger,  but  abound  Icfs  in  fugar.  It  is,  therefore,  lefs  detrimental  to  fow  too  thick, 
than  too  fparingly. 

12.  It  has  before  been  remarked,  that  the  praftice  of  pulling  the  leaves  from  the  plant 
i)ught  to  be  carefully  avoided ;  but  this  obfervation  relates  only  to  the  green  vegetating  leaves. 
The  under  leaves  frequently  turn  yellow  and  die,  and,  in  thefe  circumftances  of  decay,  they 
may  be  taken  off,  ai)d  will  afford  the  farmer  fome  aififtance  in  a  fcarcity  of  food,  without 
injury  to  the  culture  of  our  root. 

13.  Refpeding  the  choice  of  the  feed,  befides  its  early  and  perfeA  ripening,  regard  mud 
be  had  that  it  be  not  obtained  from  roots  which,  after  their  germination,  have  been  tr;inf- 
plantcd  on  feed-beds  \  but  from  fuch  as  remained  on  the .  fpot  where  they  grew  from  the 
capfules,  till  autumn,  and  which  likewife  have  produced  the  true  oblong,  thin,  conical  rootsf. 
This  is  neceflary,  becaufe  fuch  a  feed  from  untranfplantcd  plants  produces  roots  more  par* 
^king  of  the  fpindle-form ;'  whereas  the  feed  from  the  tranfplantied  roots  formic  thicker,  and^ 
a(  the  b^t  time,;  (botter,  and  on  the  lower  parts  roundiOiFy  terminated  roots. — The  Art  of 
Gardening  affords' nuinerdus  ioftances  of  the  eSefl  of  this  management  of  feed  plants,  dif- 
ferent from  thofe.  that  .aref.to.bc  produced  from  their  feed.  The  feeds  obtained  from  un- 
tranfplanted  lettuce  yield,  on  being  fown,  plants  which  but  extremely  feldom  form  any  heads, 
and  never  obtain  any  firmnefs.  The  feed  of  a  ioofe«  and  not  tranfplanted,  cabbage,  never 
produces  white  cabbage,  but  a  loofe  cole,  not  (hooting  into  a  head.  The  feed  of  fellery,  if  not 
procured  from  a  plant,  Which  bytfonfplantation  has  bee  ti  liw  mccl  into  a  knob  or  nodule ;  biit 
from  fellery  which,  for  want  of  tranfplantation,  has  produced  rather  fibrous  rool^,  y^lds,  on 
being  fown,  only  herb,  and  no  nodules.  I  am  convinced  of  the  truth  of  thefe*  affertlons 
from  my  own  experiments,  and  appeal  to  what  Luder  and  Cermerjhaufen  have  written  on  this 
fubjedl,  as  men  whofe  fcience  and  accuracy  will  not  be  difputed. 

14.  Among  the  fpindle-lhapcd  runkelriibes  there  exifts  a  variety  as  to  their  colour. 
Some  have  a  pale  red  rind,  and  are  internally  quite  white  \  others  with  a  rind  ufually  of 
a  more  deep  red,  are  intemdlly griped  reddijh\  others  again  of  a  more  or  lefs  deep  red  have 
red  circles'^  and,  laftly,  there  arc  (bme,  which,  with  an  almoft  white  rind,  have  the  internal 
part  yellow. —  Thofe  which  are  white,  with  a  light  red  rind,  deferve  the  preference  beyond 
all  others.  For  they  yield  much  fugar,  and  an  agreeable  fvfreet  fyrupj  which,  if  well  prepared,, 
has  no  tafte  of  the  root. 

•  The  author  has  not  faid  whether  he  means  the  large  or  the  fmall  Magdeburg  or  Berlin  acre.— The  for- 
mer contains  53771*  and  the  fecond  24197  French  fquare  feet.  Probably  he  underftands  the  large,  in  the 
common  ufc  of  the  language. — Tranflator. 

f  It  is  in  autumn,  as  noticed  before,  tha(  the  runkelriibes  muft  be  gathered,  and  kept,  duriog  the  win* 
ttri  defended  from  the  fkoft  j  becaafe  they  are  biennial  plants. 

15.  The 


14*  On  tbifaciUrini  Princtpb  $fPbmt, 

15.  The  red*ftriped  or  circled  roots,  whoTe  rind  idfo  it  alwajs  of  a  darker  cdoiir^  afford 
iugar  indeed;  but  the  fyrup  is  bad,  on  account  of  its  tafte  of  die  root,  which  cannot  be  removed 
but  by  expenfive  chemical  procefles.  The  runkelriibes  of  a  white  rind  and  yellow  internal 
part  do  ceruinly  aiFord  moft  fugar,  which  (hoots  very  readily  into  large  cryftals;  but  their 
iyrup  being  of  an  extremely  dilgufting  tafte,  is  <of  no  ufe,  when  raw  fugar  only  ts  made. 
Even  the  fugar  itfelf,  prepared  from  diefe  roots,  is  not  eafily,  but  with  difficulty,  cleared  of 
that  tafte  in  the  condition  of  raw  fugar;  though  it  certainly  diiappears  in  refining.  For  diis 
reafon,  this  laft  variety  of  the  runkclriibe,  that  contains  fo  much  fugar,  is  not  to  be  totally  re- 
jefled,  but  is  rather  profitable  in  the  manu&dory  of  fugar.  More  efpocially,  if  not  intended 
CO  be  employed  as  raw  fugar,  and  if  the  acquifition  of  the  fynip  be  difregarded. 

x6.  It  is  fufficicntly  proved,  from  the  phyfiology  of  plants,  that  die  matter  §/ tight  has  a 
great  (hare  in  the  formation  of  fome  of  their  conftituent  parts,  as  to  quality,  and  confequently 
'  on  :^eir  mutual  proportions.    I  (ball  here  mention  one  or  two  in(famces. 

While  afparag^is  is  de(eiided  againft  die  light,  it  becomes  fweet,  and  of  a  pleafant  tafte  | 
but  if  light  has  afted  upon  it,  merely  for  a  (hort  time,  it  lofes  its  fweetnefs  and  turns  bitter* 

Endive  likewife  kaS  a  tough,  har(h  tafted  leaf,  provided  it  be  expofed  to  the  free  adioa 
of  light  On  die  contrary,  when  the  inner  leaves  are  defiaided,  by  tying  die  outer  ones 
together,  they,  cban^  their  colbur,  which  paili»  from  green  to  yellow;  the  fiilmie(s  of 
thetr  texture  is  weakened;  diey  become  tender,  foft,  brittle,  and  fiill  of  juice ;  and  their 
tafte,  which  was  almoft  difgufting,  becomes  mild  and  agreeable.  All  diefe  changes  produced 
in  the  external  appearance  and  flavour  of  plints,  by  die  preience  or  abfence  of  the  matter  of 
light,  can  only  originatf  from  the  different  nudiicatiom^  whidi  diis  matter  of  light  efttda 
cither  in  the  nature  of  their  conftituent  parts,  or  in  their  mutual  proportions. 
i>  f  7.  Thefe  ob(ervations,  depending  on  refulu  generally  known,  led  me  (everal  3rears  ago 
to  make  experiments,  in  order  to  difcover  whether  the  matter  of  light  contributes  in  general 
te  the  tncficfe  or  deenaft  of  any  certain  conftituent  part  of  plants,  prindpalfy  and  exclufively  f 
whedier  this  a£tionhave  the  fame  efficacy  upon  all  the  parts  of  plants  ?  or  whether  the  matter 
of  Ught  does  increafe  or  diminijh  the  lame  conftituent  part  of  a  plant,  in  its  various  parts,  as 
r^sts^  Uawi^fr^itj  &c*  i  To  avoid  prolixity,  I  (ball  not  delcribe  the  feveral  experimrnts 
I  have  made  for  the  porpofe  of  anfwering  thefe  queftions,  either  with  plants  growing  in  open 
air,  or  cultivated  in  hot-houfes,  and  more  efpecially  thofe  made  with  the  (ugar-cane  in  the  hot* 
houle.  I  (hall  only  mention  thofe  refults  which  bear  any  relation  to  the  prefent  fubjed, 
adding  fuch  obfervations,  or  well-known  hSts,  as  tend  to  confirm  thofe  refults. 

The  following  are  the  cefults  of  my  refearches : 

(a)  That  the  abfence  of  light  augments  the  faccharine  Cquor  in  almoft  all  roots,  or  in 
the  germs  arifingfrom  them;  diat  its  prefence  dimini(hes  it;  and  that  to  (hade  the  whole 
furfacc  of  a  piece  of  ground  on  which  fuch  roots  are  raifed,  adds  very  much  to  the  increafe 
of  their  faccharine  matter. 

<b)  That  the  matter  of  light  has  not  the  (ame  efficacy,  but  rather  one  of  an  oppofite  kind, 
on  die  other  parts  of  pkmtsi  for  inftance,  the  fruits,  the  (accharine  matter  of  which  is  aug- 
mented 


Expcrinuniai  Cmnparifin  tfSumdard  Aifo/jkNti  243 

mented  by  the  prefence  of  the  matter  of  light,  indi  on  the  contrar}^  b]f  its  abfence  the  forma- 
tion of  fugar  in  diem  not  only  ntardii^  but  ia  tverf  odb  diminificd. 

(Tbi  t9nclu/kn  Ar  9ur  mxuj 


Jfppendix  to  Sir  GiMGM  SbUCZBURG  EriLTK^JS  Pafer  *  M  the  Means  tf  afcertalning  if 

Standard  ej  Weight  and  Miafurcm 

(§1..  44»)  OINCE  the  writing  of  die  preceding  Memofi*^  1  luve  had  an.  opportunity  of 
examining  three  other  firales^  divided  into  inches  or  ecluaT  (ttPMi  of  confiderable  authority  in 
this  country,  having  been  executed  by  the  late  Mr.  J.  Bl&l>.  thave  allb'  compared^  At 
old  ftandard  in  the  Exchequer,  of  the  time  of  Henry  VII.  tadlvhioh  It  ConlTdfcred  to  be  the 
mcft  ancient  authority  of  this  fort  now  fubfifting:  thefe  o&itrvatloii^  £  ffattec  myfdf,.  tHc 
Royal*  Society  will  be  defirous  of  pofleffing. 

(§.45.)  The  firft  of  the  abovementioned  fcalesbelbnged'tothe  late  General  Ror,  and  was 
purchafed  by  him  at  Mr.  Short's  fale,  the  celehmted  optician;  itj  was  u(ed  by  him  in  his  * 
operations  of  meafttring  a  bafe  line  on  Hpualtbw^UBtth*.  (See  PhiK  Tranf.  vol.  LXXV.) 
It  was  originaliy  the  propert/of  Mr.  G.  Gil  ABAMt  has  the  name  of  Jonathan  Sisson  en* 
graven  upon  it^  but  is  known  to  have  bc^a  divided  by  Mr.  Bird,  who  then  worked- with 
old  Mr.  SissoN.  It  is  42  inches  long^  divided  intatenths^  widi a  vernier  o£ioo.at  one  end^, 
and  of  jo  at  the  other,  giving  the  fubdi vifions  of  50oths,  and  lOOoAli  Df  an  inch, 

(f .  4dL)  The  feeond  is  in  the  pofleOion  of  AL£x.\^D£k  AtJBBitT^  £lq.  mid  formerly 
belonged  to  Mr»  Harris,  of  the  Tower^.  conuiiis  60  inches^  divided,  into^teadis,.  with  a 
vcrnieri  like  that  of  the  preceding.     It  is  one  iochibroad,  and*0|2  tbick». 

(§•  47*)  '^^^  ^^1^^  ^^  prefentcd  by  Alexander  Aubert,  Efi|.  and  die^late  AdmiialTCamp^ 
bell,  Mr.  Bird^s  executors,  to  tbe  Royal.  Society^,  in  whole  coftody  it  now  lemains'i.    It  con-^ 
(ifts  of  a  bfafe  rod,  92,4  inches  long,  0,57. inch  broad>  and.o»3  inch  thick;  beartng:a  fcale 
of  00  inches,  or  equal  parts,  each  fubdividedinto  lOj  with  a  vernier  at  the  commencement, 
beins  a  fi:ale  of  100  divifions  to  loi  tenths*.    Thishz%  been  called  Mr.  BinTs  own  fcale,  vi%\ 
made  for  his  own  ufe;  and  was  the  inftrument  with,  which  he  is  &id  to  have  laid  off  the 
divifions  of  his  8-feet  mural  qjuadrants..  Ic*  1^  probable  that  Mr.  Bird  made  many  more  of  thefe 
icales>  now  in  the  hands  of  private  perfons.  (one  of  which,  indeed,  I  law  at  the  Prefldent  do 
Saron's,  many  years  ago,  at  Paris),  but  thofe  ha/e  not  oome  to  my  knowledge. 
'  ($*48*)  In  comparing  General  Roy's  ^Bird's)  (bale  with  Mr.  Troughton's,  I  founds 
42  inches  of  the  formerwere  =  42,000  loinches  on  Troughton'^;  (the  thermometer  51^97;) 
36  inches  were  confequendy  ss  36,00008.- 


*  Which  WM  concluded  at  pi.  205* 

'  And 


t  ■■- 


inches. 

— • 

,0003  = 

11,9997 

+ 

,0006 

12,0006 

— 

,0004 

11,9996 

+ 

,0006 

i2,ooc6 

244  Brfirimma)  Cimpiript  tfpd^difd  Mtafurtu 

And  12  in<*e«^^rmifc*-ilFfoot  wtreiB<|tfal!nythe*r2  mches 

from  12  to  24  on  Troughton's  (ca?c        - 
The  2d  foot  -  ^  - 

The  3d  foot  -  -  -  • 

The  laa  foot  -  -  -  - 

The  mean  foot,  thci-eforc,in  Geiwral  Roy's  fcale,  taken  Irom  four  dif--^ 

ferent  feet  compared  with   Tfoughton's  tjetvvceu  the  12th  and   24th  >  I2,cooi2 
inch,  is  as  12  to  -  •  -  -  -  -  -  j 

That  Is,  general  Roy's  fcale  \i  fongeft  on  r  foot  by  fo  fnuch,  aftd  Ibngcr 

on  3  feet  by  -  .  U*  '       '-    *  -  •  «  ,00036 

And  the  grcateft  probable  error  from  the  inequality  in  the  dlvilions  13  abfiut     ..,0005 
Andthe  mean  prpbablaerrof  ftout  -  -  ."  jOOP3 

(§•  49-)  Mr-  Aubcrt^|fcqJc,  Cifl^p^Ved  wit^'  Mr^  Tfpiighton's,  was  as  follows:  58  inche? 
ircrc  equal  to  57,9982  |nches'on  Troughton's;  (thermometer  at  5i°,0i)  vi%.  Mr.  Bird's 
imeafure  was  fhorteft  ^018 ;  or,  morteft  t>h  36.inches  =  ,0012, 

*'  *    *        inches.     -^ 

And.  12  inches,  or  ift  foot,  on  Mr.  Aubert's         =  11,9999 

'^d.foot,  -  =r  12^0005 

.    ;:     .       3<*/00t,'      :  .  11,9996 

'    4th  foot  ;'•      -  12,0019 

.5th  ifA  i-^-  -    •  12,0006 

Therefore  thetnean  foot  is        -  '    ^   '^  -    ^^  12,0005 

The  greateft  errori'ln  this  fcale  appears  to  be  about  .=:  ,001 2         ■         • 

And  the  mean  probaWe  error  -»  =  ,0006  - 

(§•  50«).The  Royal  S^jety^^  Icale,  coifipared,  was  as  follows:  58  inches  on  Mr,  Bird's 
^ere  equal  to  5799991^  inches  oh  Mr.  Troughton's;  (thermometer  50^,5 ;) 
f/iz.  Mr.  Bird's  meafii);e  was  fhorteft  -  -  -  ,00088 

Or  fliortcr  on  36  inches  -  -  -  -  -      ,00054 

J  2  inches  on  the  fame  were  equal  to  -  -  *-  3i>99967 

vi%.  Mr.  Bird's  was  Ihorteft  by       .     -  -  -  -       ,00033 

Or,  on  36  inches,  by  -  -  -  -  J       ,00037 

The  mean  of  thefe  two  comparifons  is  .*•  -  ^  ,00045 

And,  by  fo  much,  is  Mr.  Bird's  fcale  fhorter,  in  three  feet,  than  Troughton's^ 

■ 

And  12  inches,  or  ift  foot,'bf  the  Royal  Society       inches.       ") 

fcalC)  is  •  -  -  =:  1 2,000 1 3 

2d  fodt  of  ditto  =11,99957 

3d  foot- of  ditto  =12,00027 

4th  foot  of  ditto  =  1 1,99990 

5th  foot  of  ditto  =  12,00063 

6th  foot  of  ditto  =  11,99823 

7th  foot  of  ditto  =  I2,oooco 

The 


on  Mr.  Troughton's  fcale 
from  6  inches  to  -  18 
inches ;  the  thenhome* 
ter  being  at  50^,0. 


on   Troughton's   fcale;'  the 
thermometer  at  51** 


Experinuntal  Comparifon  of  Standard  Mtafmt. 


^AS 


The  mean  of  thefe  feven  feet  is  -  =1 1,99982 

And  the  greateft  error  in  thefe  divifions  -        rz  ,0008 

And  the  mean  probable  error  -  -  =:  ,0004. 

(§.  51.)  Left,  however,  it  {hould  be  fufpedled,  that  Mr.  Troughton's  fcale,  with  which 
I  have  made  thefe  comparifons,  is  not  fufficiently  correiSl  for  this  apparent  preference,  I  will 
now  give  the  refult  of  my  examination  of  that  fcale,  from  one  end  to  the  other.  I  fet  the 
microfcopcs  to  an  interval  of  nearly  6  inches,  correfily  fpeaking  it  was  6,00013  inches, 
taken  from  a  mean  of  the  whole  fcale  >  and,  comparing  this  interval  fuccei&vely,  I  found  as 
follows : 


inches,    inches. 

viz.  from    o  to     6 
6  to  12 

12   to    18 

18  to  24 
24  to  30 
30  to  36 
36  to  42 
42  to  48 
48  to  54 
54  to  60 

Mean  of  all 


Inches. 
=  .  6,00025* 

=    6,00013 

=    6,0C020 

=  6,00000 
=  6,00007 

=  6,00033 

=  5>999Bo 
=z  6,00020 

=    6,000  ID 
=    6,00023. 


Error,  or  difTerence 
from  the  mean. 

+  ,00012 

,00000 

+  ,00007 

—  ,00013 

—  ,00006 
+  ,00020 

—  >ooo33 
+  ,00007 

—  ,00003 
+  ,00010 


=  6,00013    . 

From  whence  it  appears  that  the  greateft  probable  error,  without  a  palpable  miftake,  in  Mr. 
Troughton's  divifions,  is  =  ,00033  inch;  againft  which  the  chance  is  9  to  ij  and  the 
mean  probable  error  =  ,00016;  and  that  it  is  4  to  i  the  error  doth  not  exceed  t^^S^tj  inch. 

This  accuracy  is  about  three  times  as  great  as  that  of  Mr.  Bird's  fcales,  and  about  equal 
to  that  of  the  divifions  of  my  equatorial  inftrument,  made  by  Ramfden,  in  1791.  See 
Phil.  Tranf.  for  1793. 

(§•  5^0  I  now  proceed  to  the  examination  of  the  ftandard  rod  of  Henry  VIT,  which  is 
an  oftangular  brafs  bar,  of  about  |  an  inch  in  diameter,  with  one  of  the  fide«  rudely  divided, 
into  halves,  thirds,  quarter,  eighths,  and  fixteenths;  and  the  firft  foot  into  inches.     Each  end 


is  fealed  with  a  crowned  old  Englifti    H  (Vs\  and  from  hence  is  concluded  to  be  of  the 
time  of  King  Henry  VIL  viz.  about  1490,  but  is  now  become  wholly  obfolete,  fmce  the 

•  It  IS  not  pretended,  that  in  this  and  the  foregoing  obfcrvations,  the  qmntity  of  any  interval  can  be  de- 
termined to  the  precifion  of  the  on«-hundred-thoufandih  part  of  an  inch;  but  it  is  prt-fumcd,  that  with  the 
aififtance  of  the  microfcopcs,  the  ten-thoufandth  part  of  an  inch  becomes  vifibic  ;  and,  as  ^  mean  is  taken 
from  3  or  4  times  reading  off  the  micrometer  at  each  trial,  it  has  been  deemed  not  unrcafonable  to  fct  down 
the  quantities  to  five  places  of  decimals. 

Vol.  III. — September  1799.  K  k  introdu(Slion 


246  Ei^imental  Comparifin  cf  Standard  Mutfitrts. 

introduaion  of  the  ftandard  of  Queen  Elizabeth ;  but  fuch  as  it  is,  1  have  thought  proper  to 
examine  it,  and  find  it  as  follows:  Inches. 

On  this  rod,  y  or  the  ift  foot,  is  equal  to  1 1^973  on  Troughton's. 
the  2d  foot  is  -  1 1,948 

the  3d  foot  is  -  12,047  £nor,  of  diflRRcno* 

■  Difference.  of  3  feet«  ^ 

The  mean  foot  Is            -             ii>989  —  ,oii  —  ,033 

4  yard,  or  18  inches  -              =  179946  —  ,054  —  ,108 

y  yard,  or  24  inches  •              =  23,921  —  ,079  —  >ii8 

-^  yard,  or  27  inches  -             ==  26,937  —  ,063  —  ,084 

i  yard,  or  31 1  inches  -            =  Z^AAl  —  >oS7  —  >o6s 

41  yard,  or  33^  inches            .           =  33,665  —  ,085  —  ,091 

Entire  yard,  or  36  inches         -          =r  35>966  —  ,034  —  ,034 

And  the  mean  yard        •        -  =  35,924  Mean  — *  ,076 

And,  by  fo  much,  Mr.  Troughton's  meafure  is  longed:. 
And  the  probable  error,  in  the  divifions  of  this  old  ftandard,  is  about  y^^  inch* 

(§•  53.)  It  may  now  be  defirable  to  fee  the  comparative  lengths  of  thefe  various  ftand- 
ards  and  fcales,  reduced  to  one  and  the  fame  meafure,  vi^  Mr.  Troughton's. 

36  iiiches,  on  a  mean,  of  Henry  VII.  ftandard  of  1490,  ire    tIS<S?..       ^'  ^t^^ 
equal  to  -  -  -  -        • 

■  of  ftandard  yard  of  Elizabeth,  of  1 588     *    - 
•— — —  of  ftandard  ell  of  ditto,  of  1 588 

■    ■  ■  ■  *  of  yard-bed  of  Guildhall,  about  1660 

■  *  of  ell-bed  of  ditto,  about  1660 
t  ♦  of  ftandard  of  dock-makers'  company,  1671 
,  ■              *  of  the  Tower  ftandard,  by  Mr.  Rowley,  about 

1720  -  *         -  .         -  -  -  36,004       +  >oo4 

of  Graham's  ftandard^  by  SifTon,  of  1742,  viz. 


3S»9a4 

—  ,076 

>o3 

36,015 

+  ,015 

,04 

36,0x6 

+  fOi6 

,04 

36,032 

+  J032 

36,014 

+  >oJ4 

3S.97* 

—  >o2a 

Kue  £  -      .  -  •  =36,0013     +  >ooi3 

—  Of  ditto,  ditto,  vi«.  line  Exch.  -  =:  35^9933     —  ,0067 

of  Gen.  Roy's  (Bird^s)") 

all    made    probably 
►  between    the    years  < 
1 745  and  1 760. 


fcale 

..     ■  ofMr.  Aubert's,  ditto. 


ditto 

of   Royal    Society's, 


ditto,  ditto  -  J 


=  36,00036  +  ,00036  ,0003 
^  35)99^^0  +  ,00120  ,0006 


L  =  3S>9995S  +  >ooo45  *<x^4 


of  Mr.  Bird'sparliamentaryftandard,  of  1758       ==  36,00023  -f  ,00023 

of  Mr.  Troughton's  fcale,  in  1796         -  =r  36,00000       ,00000  >oooi 


^  Thefc  Four  quantities  arc  uken  from  Mr.  Graham's  account,  in  the  Phil.