Mr. le cerf on a .new-invented Compafs. 951 
watches, and all kind of wheel machines, this paper ap- 
pears to me to be very worthy of the attention of the 
Society. It is to be regretted, that the author does not 
enter into a greater and more minute detail upon the 
fhape of the working-teeth, &c. as this, in my opinion, 
will, ir feveral cafes, materially afFedt the very fimple, 
general rules which he has elegantly laid down. 
I am, sir, with true regard, 
Your very obedient, humble fervant, 
MAHON. 
§ 1. '"pH IS machine may be called a compafs of geo- 
"*■ metrical and mechanical proportion; its pro- 
perty is to refolve a great number of problems analogous 
to the theory and practice of watch-making, in a man- 
ner which is at the fame time very evident and infinitely 
more 
Defcription cPune Machine de nouvelle Invention , aujji variee dans 
fes Effets que necejfaire pour determiner les parfaits rapports 
entre les differens mobiles agijfans par Leviers et par Engr'e - 
nages. Par Monjieur Le Cerf, Horloger a Geneve. 
■§ i. /\N peut appeller cette machine, compas de proportion geometrique et 
mechanique, puis qu’il a ]a propriete de reloudre une quantite de 
problemes analogues a la theorie et a la pratique de l’horlogerie d’une maniere 
