376 NATURAL THEOLOGY. 



and we perceive the resemblance to the wheel 

 and axle. The teeth of the wheel move with a 

 rapidity in proportion as the circumference of 

 the wheel is distant from the axis or centre of 

 motion. 



The wheel and pinion may be used either to 

 accelerate motion, as when the power is applied 

 to the pinion, or to diminish it, as when the power 

 is applied to the teeth of the wheel, and conveyed 

 through the leaves of the pinions to another 

 wheel. 



If there be forty teeth in a wheel, and this 

 wheel plays into the pinion of another wheel hav- 

 ing ten leaves, ten of the teeth of the first wheel 

 will cause the second to complete its circle ; and 

 as there are forty teeth in the first wheel, the 

 second will revolve four times for one of the 

 first. 



If things were reversed, and the motion com- 

 menced in the second wheel, so as to be commu- 

 nicated to the first, the mechanism would then 

 have the eflfect of diminishing the motion to one 

 quarter. In both these ways ai-e the wheel and 

 pinion employed in the watch. 



The power moving the wheels of a watch is the 



