234 Introduction to the Study of Science 



and wood together, less than 3 per cent of the total power 

 utilized by the industries of the United States. Falling water, 

 the use of which is rapidly increasing for the direct production 

 of power as in the hydro-electric plant, furnishes about 20 per 

 cent. Wind, utilized for running pumps and small electric 

 generators in rural districts, and all other sources make up the 

 small remainder, or 2 per cent. 



Power and the coal supply. The industries of our country 

 utilize annually more than thirty-five million horse power. 

 About twenty-seven million of this is furnished by heat from 

 fuel. Falling water contributes more than six million, which 

 amount is being gradually increased. The current rate of 

 consumption of bituminous coal is over 450,000,000 tons, and 

 of anthracite about 85,000,000 tons a year. At this rate 

 the known coal supply will last according to authoritative 

 estimate for a period of seventy years for anthracite, and six to 

 eight times seventy for bituminous. As the supply approaches 

 the point of exhaustion and becomes increasingly difficult to 

 mine, the cost must increase accordingly. In order to economize 

 the known resources of coal, it is necessary to make all possible 

 use of other available sources of power. 



Available water power. The amount of power available 

 from falling water is, according to one estimate, about 100,000,000 

 horse power. This estimate is based upon several conditions. 

 First, it requires the construction of reservoirs to collect and 

 conserve the flood waters and all suitable stream flow of the 

 country. Second, it requires the conservation of the forests, 

 and the reforestation of watersheds from which the forests have 

 been removed. Forests are supposed not only to protect 

 watersheds, but also to store up rainfall, effecting more equal 

 distribution of stream flow throughout the year. Third, it 

 seems to require a single, central, and wise control of water 

 power and all the conditions upon which the water supply 

 depends, together with the protection of the public interests 

 in granting the use of water-power privileges. 



