Proportion Compafs.- 989 
branches; this is done the more eafily to put the two 
Aiders facing each other in all cafes. 
When one wifhes to meafure pieces which are larger 
than the aperture of the jaws allows, one puts the Aiders 
on the edge of the fmall points when there is a hole in 
the middle of the branches where the aperture of the 
angle is only a Ifxth part of the .divifion of a foot, that is, 
if the angle upon the diviAon of the foot is Ax inches 
open, , that of the middle will , be. only one inch and fo 
on. 
§ 55. As to the other machine of brafs, with two por^- 
tions of a circle divided as far as half a quarter of a de-p 
gree, one may with the greateft preciAon verify upon it : 
the true proportion or thicfcnefs of the pinions by the 
degrees of rife required by making the different -wheels 
from 
fur les deux branches, et cela pour mettre plus facilement dans tons ks cas les ~ 
coulans parfaitementvis a vis. 
Lorfqu’on voudroit. mefurer quelq.ues pieces plus grande que Touverture des 
machoires ne le permet, on met les coulans fur le-bord des petits points ou il y a 
un trou au milieu des branches ou Touverture de Ton angle n’eft que la fixieme 
partie de celui de la divifion du pied; c’eft a dire fi Tangle fur la divifion du 
pied eft ouvert a. fix pquces, celui du milieu ne le fera qu’a un pouce, ainfi du 
refte. 
§55. Quant a Tautre machine en leton a deux portions de cercle divifee 
jufques aun demi quart de degre; Ton peut y verifier avec la plus grande precis 
fion, le. jufte rapport des pignons fbk groffeur par les degres de levees requifes* 
