Proportion Compafs. 969 
raife the required degrees, becaufe the aperture of its 
angle does not anfwer to that of the teeth of the wheel: 
for inftance, a pinion of 6, which is T \ths of a line final ler 
than the true rule makes it, will raife only 55 0 , when 
the tooth of the wheel has carried the tooth of the pi- 
nion as far as its extremity on the aperture of its angle 
allows, it is forced to leave it before the tooth which fol- 
lows is come to the fame place from whence the other fat 
off, confequently it falls 5 0 which are wanting to its juft 
rife; this is what occafions the precipitations of the ba- 
lance, which are fo difagreeable to the ear, that one is in 
much greater hafte to correft them than to prevent the 
retardations which, no doubt, arife from the other extre- 
mity ; that is being obliged to make a forced rife, or a 
greater one than the true proportion of the diameters re- 
quires, 
ne pourra lever les degres requis, parce que l’ouverture de fon angle ne repond 
point a celui des dents de la roue; parexempie, un pignon de 6 de X V de iigne 
pins petit que la veritable regie le fixe, ne levera que 55 0 , la dent de la roue ayant 
mene 1’a’de du pignon aufii loin que fon extremite ou l’ouverture de fon angle le 
permet, eft oblige de Pabandonner avant que 1’aile fuivante arrive a la memo 
place d’ou l’autre eft parti foit de la ligne des centres, il fait par confequent 
une chute de 5 0 qui manquent a fa jufte levee, c’cft ce qui caufe les precipita- 
tions du balancier qui choquent fi fort Pereille. C’eft pourquoi on eft beaucoup 
plus emprelfe a les corriger qu’a prevenir les lenteurs, qui fans doute provicn- 
nent de Tautre extremite, parce qu’etant oblige de faire une levee forcee ou plus 
grande que le jufte rapport des diametres exige, ils eprouvent un contraft ou 
Vol. LX VIII. 6 E arcboutement 
