MECHANICAL PARADOXES. 



and chain being indicated by dotted lines. 

 The distance from A to C is the length of an 

 ordinary straight crank. 



The inventor's argument was as follows : 

 A longer crank gives a greater leverage to 

 the foot ; therefore, since the length of the 

 crank limb A B is made greater than the 

 distance A C, which is the length of an ordinary 



FIG. 25.-FALLACY OF 

 .THE BENT CRANK. 



crank, a pedal placed at B would allow the 

 foot to exercise greater turning force. But to 

 move round a circle with the radius A B would 

 oblige the foot to take an inconveniently large 

 sweep ; so the arm B C is fixed at an acute 

 angle with A B, so that a pedal fixed at its 

 end C will be at the usual distance from the 

 crank axle A. This shorter arm is in such a 

 position that when the long arm is beginning 

 the most effective part of the stroke, B C is 



106 



