SHADE TREES AND FORESTS 



489 



FIG. igi. Forested watershed in the San Bernardino Mountains, California. 



a regular, even flow during all the season, a matter that 

 exerts important influences on our daily life, as we shall see 

 in the paragraphs that follow. 



Streams for water power. Coal now supplies us with most 

 of the power to run our factories, to furnish our electricity, 

 and to run our locomotives and other machines so essential 

 in our life. But the supply of coal will some time be ex- 

 hausted ; then man must find some other source of power. 

 Our streams will furnish a large part of that power, and the 

 force of the flow may be used over and over at different 

 localities on the stream. In order that the best use may be 

 made of these streams, it is necessary that there should be 

 an even flow throughout the whole year, so that machines 

 may be run all the time and not be obliged to stop because 

 the river is low. It is very important that the people look 

 forward to the time when they must depend more upon 

 water power. They should not allow private capital to 



