the Rotatory Motion of Bodies. 291 
efficacy of all the forces acting on the feveral particles of 
that body to turn the fame about the line hci will 
be obtained by computing the fum of all the forces 
adbing on the faid body. 
The computation of fuch equivalent force will in moft 
cafes be abridged by obferving that, if pk be continued to 
// // 
p fo that kp be = kp, the efficacy of the force on the par- 
// 
ticlep, to turn the body about the line hci in oppofition 
to the force on the particle />, will be reprefented by 
It 
v/ A " ' * ■■ — - 
the equivalent force -- x mn x x z -'vf+m l ~n z x wx a&ing 
on the line oco_at the diftance g from c ; and that there- 
// 
fore the efficacy of the two forces on p and p, to turn the 
body about hci, will be reprefented by the equivalent 
force X mnx.w 2 —x z adting on the line ocq_, at right 
angles to the plane doeifqgh, at the dillance g from c. 
3. Pig. j 1, i t,. If the body be a cylinder, afpheroid, 
or the like, and its proper axis be lituated in the line c k, 
// 
the ordinates correfponding the ab/ciffic kp.-, kp, in the 
circular fedlion hi whofe center is k, will each be paral- 
lel to that diameter paffing through c, about which the 
body will be urged to turn ; and each of thofe ordinates 
will be = \ly % —w z , y being the radius of fuch fedtion. 
P p a Therefore, 
