THE WHEEL AND AXLE 



179 



raising a flag on a flagstaff. By means of a 

 second pulley a horse pulling in a horizontal 

 direction can raise a weight vertically upward 

 (cf. Fig. 20, 26). 



If we arrange two pulleys as in Fig. 176, two cords 

 support the weight, while only one is supported by the 



power; hence a power of 1 pound can Q n 

 support a weight of 2 pounds. We get this n d One Fixed 

 advantage because the cord on which we 

 pull must descend twice as far as the weight rises. 

 If there are three cords (Fig. 177) supporting the 

 weight, and one supported by the power, 1 pound can 

 lifts. 



FIG. 177. 202. The Wheel and Axle. In the wheel 

 and axle (Fig. 178) the power applied on the 

 wheel must move a distance 

 equal to the circumference of the wheel, 

 while the weight attached to the axle 

 moves only the circumference of the axle. 

 The wheel in the figure has a circum- 

 ference 3 times that of the axle; therefore 



1 pound on 

 =j) the wheel 

 l\ will support 





ft=3 



CD 



FIG. 178. 

 Wheel and Axle. 



FIG. 179. 

 Winch Used for Raising of Water. 



3 pounds 

 on the axle. 



The winch, or windlass (Fig. 

 179), is a form of the wheel 

 and axle in which the power is 

 applied to a crank. To raise 

 the weight a distance equal to 

 the circumference of the axle, 



