MECHANIC POWERS. 51 



of the pinion 5, then the pinion will go 12 times 

 round for once of the wheel, because 60, divided 

 by 5, gives 12 for a quotient. 



Hence, if you have any number of wheels act- 

 ing on so many pinions, you must divide the product 

 of the teeth in the wheels by those in the pinions; 

 and the quotient will give the number of turns of 

 the last pinion in one turn of the first wheel. Thus, 

 if a wheel A (Plate 3. fig. 9. of 48, acts on a pinion 

 B of 8, on whose axis there is a wheel C of 40, 

 driving a pinion D of 6, carrying a wheel E of 36, 

 which moves a pinion F of 6, carrying an index : 

 then the number of turns made by the index, will 

 be found in this manner: V x V* V = '*sl°=240, 

 the number of turns which the index will make 

 while the wheel A goes once round. 



Any number of teeth on the wheels and pinions 

 having the same ratio, will give the same number 

 of revolutions to an axis: thus, 5£^%°fc! B , ="W 

 —240, as before. It therefore depends upon the 

 skill of the engineer, or mechanic, to determine 

 what numbers will best suit his design. 



It is evident, that the same motion may be per- 

 formed, either by one wheel and pinion, or by 

 many wheels and pinions, provided the number of 

 turns of all the wheels bear the same proportion 

 to all the pinions which that one wheel bears to its 

 pinion. 



When a wheel is moved immediately by the 

 power, it is called a leader ; and if there is another 

 wheel on the same axis, it is called the follower. 

 Thus A, being moved immediately by the power, is 

 to be considered as a leader, and B as a follower; 

 the wheel C being driven by B becomes a leader, 

 and D a follower; E (Fig. 10.) is a leader, and the 

 cylinder F may be considered as a follower. 



E 2 



