66 



GENERAL SCIENCE 



Water Power. - - The power of water is very great. 

 As we watch the water in a small stream trickling over 

 the pebbles, we can hardly appreciate the vast power 

 that results when the stream is dammed and a consider- 

 able head of water maintained. The force of the waves 



f FIG. 62. Flour Mills on the Mississippi River. 



and of flood waters often does immense damage to ship- 

 ping, to crops, and to the works of man which have been 

 built in their paths. 



It is much more difficult to row a boat or to swim against 

 the current of a stream than with it, since water exerts 



