236 Introduction to the Study of Science 



of the heat developed from coal is actually utilized, the rest 

 escaping as loss or waste. In a moderately efficient plant it 

 costs an average of thirty dollars a year to generate one horse 

 power from coal. This includes the cost of plant, maintenance, 

 labor, and fuel. Most plants, however, do not keep the cost 

 per horse power much below fifty to sixty dollars a year. Only 

 the most efficient power plant working at full capacity every 

 day in the year can bring the mean cost as low as fifteen dollars. 



It is generally estimated that it costs on the average just 

 about one half as much per horse power, or fifteen dollars as 

 against thirty dollars for coal power, to generate power from 

 falling water. And at least one half of the total amount of 

 power now developed from coal might advantageously be derived 

 from falling water. The total saving of coal by the substitution 

 of water power would be not only large, but also widely dis- 

 tributed. The known coal supply would be conserved, thereby 

 increasing by just so much the wealth of the nation, that is, 

 the wealth of all its citizens. The cost of coal to the consumer 

 would be kept at a reasonable figure. At present its cost is 

 high and increasing too high when considered on the basis of 

 its efficiency in generating utilized heat ; and it must increase 

 as the supply decreases. The use of water now running to waste 

 would thus not only postpone additional increase in the cost of 

 coal for the consumer, but also reduce the cost of power to a 

 remarkable degree (cf. Fig. 79). 



To illustrate the economy of coal that may be effected by the 

 use of falling water for the production of power, we may refer 

 to the hydro-electric plant at Big Creek, California (Fig. 69). 

 This plant will furnish 350,000 horse power to Los Angeles and 

 vicinity. With a total head or fall of about four thousand feet, 

 utilized in two power stations, and the immense volume of water 

 supplied by the extensive area of the watershed, this seems to 

 be a reasonable estimate. With such a fall one cubic yard of 

 water is equivalent to fifteen pounds of coal in producing energy. 

 It takes on the average six pounds of coal per hour to generate 



