MAWS STRENGTH NOT SUFFICIENT FOR MACHINES 175 



for him (Fig. 119). One sees dotted over the country wind- 

 mills large and small, and in Holland, the country of wind- 

 mills, the land- 

 owner who does 

 not possess a 

 windmill is poor 

 indeed. 



For genera- 

 tions running 

 water from 

 rivers, streams, 

 and falls has 

 served man by 

 carrying his logs 

 downstream, by 

 turning the 

 wheels of his 

 mill, etc.*, and in 

 our own day 

 running water is 

 used as an in- 

 direct source of 

 electric lights 

 for street and 



house the en- FIG. 119. The windmill pumps water into the troughs where 



cattle drink. 



ergy of the fall- 

 ing water serving to rotate the armature of a dynamo (Sec- 

 tion 310). 



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 automobiles. 



In the following Chapter will be given an account of water, 

 wind, and fuel as machine feeders. , 



