ENDLESS-CHAIN POWERS. 165 



Fig. 147. 



Chv,rn worked by dog-power. 



The same principle has been lately adopted with 

 great success in the application of horse-power to driv- 

 ing thrashing-machines, sawing wood, and to various 

 other purposes. Instead of India-rubber straps, strong 

 cast-iron chains are used, which are made to run 

 smoothly and with very little friction over a succession 

 of small iron wheels, which support the weight of the 

 horses on the moving platform {Fig. 148, on the fol- 

 lowing page). 



The power of these, machines, and the amount of 

 friction in running them, may be easily ascertained by 

 the rule, already given in a former part of this work, 

 for determining the power of the inclined plane ; for 

 the only difference between the endless-chain and a 

 common inclined plane is, that in one the plane is 

 fixed, and the body moves up its surface, and in the 

 other the plane itself moves downward, and the weight 

 or animal upon it remains stationary. The same prin- 



