Fundamental Property of the LEVER. 403, 



be reprefented by B / rz 4- B 0. In the fame manner, if the two 

 equal forces B m, B n, act upon the lever at B, their joint force 

 will be reprefented by B &>, and one of them, B m, will be repre- 

 fented by B X — ~ B 0*. Confequently the power of the two 

 forces BM, B ;;;, to turn the lever round its centre of motion, 

 is reprefented by B /, B X, refpectively ; that is, the force BM 

 is to the force Bm as B/ is to B x; that is, as AY is to Ay, the 

 perpendiculars let fall upon the lines of their direction. 



3E2 XIV 



