<62 Mr. vince’s Investigation of the 
then from the laft Corol. the center of gravity g, of the 
three bodies, will move in a line parallel to the direction 
of the force communicated. In the fame manner it 
may be proved for any number of bodies. 
SCHOLIUM. 
The method here made ufe of to determine the point 
of rotation in ipfo motus initio, when a Angle force ails 
at any point d, may be applied, when any number of 
forces ail at different points at the fame time. For let 
(fig. i .) a , (3, y, Sec. reprefent the forces ailing on the 
lever at the points d, e, f, Sec. refpeilively ; then from 
the fame principles the effeil of all the forces on a : 
the effeil on s : : dL + ^ + X + Sec. : + Sec. 
which quantities put equal to p and eg refpeilively, and 
then 
L • S 
A * B 
: : a m : b# : : ac : bc, from whence it ap- 
pears, that (putting gc + ga = ac and gc - gb = 
bc) the diftance gc 
A x Cgx AG + B x P x BG 
The 
B x P — A x Q_ 
fame conclufion might have been deduced from this 
confideration ; that if any number of forces ail on a 
lever, the effeil on any point of that lever is juft the 
fame as if a force, equivalent to the fum of thefe forces, 
had 
