Proportion Compafs. 957 
equal to this in ftths, or one line; but for 2, 3, and 4 
revolutions, and fo on, one muft add ~ths of a line to 
the radius already laid down, for as many revolutions as 
the pinion muft make more than the wheel, a wheel of 
1 2 teeth will confequently have 4ft hs of a line radius or 
diameter; one of 18 teeth and Ifths; one of 24 teeth 
ftths, and fo on. 
§ 9. The fame thing holds true in all the other- 
pinions, let the. number of them he what it will, where 
the fame rule is to be obferved. Thus upon 1 o revolu- 
tions of a pinion of 1 o one muft deduct from the dia- 
meter of the wheel one diameter of the pinion;, as many 
upon eight revolutions of a pinion of eight ; upon feven ; 
of a pinion of feven as many; upon fix of a pinion of 
fix.* 
qui doit faire le rayon dela roue pour la premiere revolution fera egal a celui ci 
en 12 douziem.es foit une ligne mai& pour 2, 3, et 4 revolutions ainfi de fuite on ? 
ajoutera 10 douziemes de ligne au rayon deja pofe, pour autant de revolution - 
que devra faire le pignon de plus que la roue; ainfi une roue de 12 dents aura 
de rayon ou de diametre 22 douziemes deligne^ cel le de 18 dents 32. douziemes; 
de 24, 42 douziemes, &c. 
§ 9. II en ell dememe de tous les autres pignons, de tel nombfe que ce foit, 
oil il faut obferver la meme regie, ainfi fur 10 revolutions d’un pignon de 10 : 
on retranchera du diametre dela roue une fois celui du pignon; fur 8 revolutions 
chin pignon de 8 autant; fur fept d’un pignon. de 7. autant; fur fix. d’un pignon 
» deft 
