Pyrometry  and  Arconiet-ry , See.  485 
Thefe  names  were  too  foon  changed,  in  calling  mea- 
fures  what  was  not  yet  fuch ; but  we  every  day  become 
more  delicate  with  relpeft  to  the  conditions  they  require ; 
and  the  progrefs  made  towards  perfecting  them,  are  the 
moll  effectual  Heps  which  have  been  made  towards  the 
knowledge  of  Nature;  for  it  is  they  that  have  given  us 
a difguft  to  the  jargon  of  fyftems,  founded  upon  mere 
hypothefes  or  deceitful  appearances,  the  confequences  of 
which  were  fpreading  fall  into  metaphyfics,  in  which  it 
occafioned  general  confulion. 
The  improvement  of  phyfical  meafures  does  not  only 
lead  us  to  a better  knowledge  of  the  immediate  caufes  of 
the  effects  thus  meafured,  but  it  affifts  us  in  decompofing 
complex  effects,  and  efpecially  in  difeovering  and  deter- 
mining the  limultaneous  effeils  which  I lhall  hereafter 
name  the  co-effe£ts  of  the  fame  caufes. 
When 
On  a change  trop  tot  la  terminaifon  de  ces  noms  etde  bien  d’autres  femblables, 
en  qualifiant  de  mefure  ce  qui  ne  l’etoit  point  encore.  Mais  chaque  jour  on 
devient  plus  delicat  fur  les  conditions  qu’elles  exigent;  et  les  progres  vers  leur 
perfection,  font  les  pas  les  plus  reels  qu’on  ait  faits  vers  la  connoilfance  de  la 
Nature : car  ce  font  ceux  qui  ont  le  plus  contribue  a nous  degouter  du  jargon  des 
fyftemes  fondes  fur  des  hypothefes  ou  des  apparences  trompeufes,.  dont  les  confe- 
quences palfoient  en  foule  dans  la  Metaphylique,  et  y boulverfoient  tout. 
Le  perfe&ionnement  des  Mefures  phvfique  ne  nous  conduit  pas  uniquement 
a mieux  connoitre  les  caufes  immediates  des  effets  mefures;  mais  il  nous  aide  a 
decompofer  les  effets  complexes,  et  furtout  a decouvrir  et  determiner  les  effets 
fimultanes,  que  je  nommerai  dans  la  fuite  les  co-effets  desmemes  caufes. 
Qiiand 
