of Mn Sme'Ato^ sO Iff vut ions on* the 
You then, proceed, in dike manner, with another fet of' 120. 
holes; that is, placing the 60th hole of theftraps to the 120th. 
hole of ft lie hoop- plate, and from it producing the 180th hole * . 
you, in like manner as before, fill up this 60 with the chaps 
and afterwards placing die 120th hole on -the ftraps in the 
120th hole on the hoop;plate, you will obtain the 240th hole 
fio that- filling up this laid, fet of 60 divifions, you have ob-s 
taxn.ed.241 holes, including 240 fpaces or divifions of the 
hoop ; and repeating this procefl ten times more, you will, in 
like manner, obtain 1441 holes, comprehending 1440 fpaces 
And this proceis being carried on in temperate weather, the, 
manner of working produces twelve fimilar operations, wherein 
the materials and tools concerned .will not only be fubjeCfc to 
very little change of temperature, but. that change, what- 
ever it is,, will be nearly fimilar in each fet of 120 holes; 
we may therefore- infer, tliat the greateft inequality, or; 
Indeed any that can be fenfihle, mull be at every 60 divifions,. 
that is, between the. 59th'.. and 60th, and between the 119th*. 
and 1 20th, both which will be equally repeated ! 2 times, in the 
whole length which is to compofe the circumference of a Circle^ , 
and which will thus be checked .thereby 1 2 times in the cir- 
cumference, and 12 times more at the intermediate diftances ; ; 
that is, with 12 matter checks, and 12 fubordinate ones, in 
t h e wool e rou n d . 
It is proper here to obferve, that in M. RoemerY method* ; 
even fixty divifions could Icarcely betrufted in an affair of great 
accuracy, on account of the objections already made, arifing 
from the points having fuch flight hold in the furface of the** 
hrafs but here the parts are held fo exceedingly firm, and the; 
* It wilt be proper, for reafons hereafter to be mentioned, to continue the 
«Uvifi$ns to: 20 holes more, making in the whole 1461 holes* 
i operation 
