HOW MACHINES LIGHTEN LABOR 



For generations running water from rivers, streams, and falls 



has served man by 

 carrying his logs down- 

 stream, by turning the 

 wheels of his mill ; and 

 in our own day running 

 water is used as an in- 

 direct source of electric 

 lights for street and 

 house. 



A more constant 

 source of energy is that 

 available from the 

 burning of fuel, such as 

 coal and oil. The 

 former is the source of 

 energy in locomotives, 

 the latter in most auto- 

 mobiles. 



In the following 



FIG. 182. The windmill pumps water into the chapter will be given 

 troughs where cattle drink. r 



an account of water, 

 wind, and fuel as machine feeders. 



