

i their axes in the same straight line: the larger 

 wheel, and the smaller the axle. The 

 cord i the >\ suspended is fastened t 



jK)wer which sup- 

 th<- weight acts by a cord coil. 



wheel, by spokes acted on by the hand, as in the cap- 

 flan, or by the hand acting on a handle, as in the tciiMitt. 



the power and weight in the 

 Wheel and Axle when in >tm. 



Let AD be the wheel and CC'B the axle; P the power 

 represented by a weight suspended 

 .Terence of the wheel 

 at A ; H r the weight hanging from 



tin- :i\l- at //. 



ice the axis of the ma 

 \cd, the condition of equilibn 



of the moments of 

 forces about this axis vanishes, 



>re 



Px rad. of wheel - TFx nuL of ax 



W rad.ofwh 



therefore -77 



rad. ot axle 



M ill be seen that this machine is only a modification of 

 the li-v.-r. In shrt it is an assemblage of levers all having 

 the same axis: and as soon as one lever has been in acti* 



comes into play ; and in this way an endless leverage is 



obtai respect, then, the wheel and axle surpasses 



a echanical advantage. mch used 



cks and in shipping. 



i ml Mechanical Power is the Toothed Wheel. 

 applied in all mn in cranes, steam- 



engine*, and particularly in cl-ck mul watch work. If two 

 lar hoops of neta! of wood havin oum- 



ited, or cut into equal teeth all the way round, 

 be so placed that their edges touch, one tooth of one circum- 



