Fundamental Property of the LEV ER. 403; 
be reprefented by BJ = 4Bo. In the fame manner, if the two 
equal forces Bm, Bz, act upon the lever at B, their joint force 
will be reprefented by Bo, and one of them, Bm, will be repre- 
fented by BA=4+Bo. Confequently the power of the two 
forces BM, Bm, to turn the lever round its centre of motion, 
is reprefented by B/, Ba, refpectively ; that is, the force BM. 
is to the force Bm as B/ is to Ba; that is, as AY is to Ay, the 
perpendiculars let fall upon the lines of their direction. 
3E2 XIV 
