Examination of Mr. Quinby’s Crank Motion. 127 
. - Pox 
the variable am, x; the effective force o) » = ae * the 
mean value of this expression, or the mean tendency to rota- 
tion, will be found by considering 2 as the ordinate of the 
centre of gravity of the semicircle AEB, in which case « is a 
mean of all the ordinates of the semi-circle : in this case 7 = 
R? |: ae ; 
ecpenent ten 6 2 eS ee OX 
Arc AE a 3.1416 R R1.5708 
6366 ; this ‘being the value of the effective force, the power 
lost, or the difference between the power applied and the ef- 
pee force, willbe P—P x-6366, or Px-3634, showing a loss 
of more than one third of the power =ppnes, 
