26 GENERAL INTRODUCTION 



and other commercial enterprises; for private dwellings; and for 

 public uses such as lighting streets, parks, etc. They do not 

 include electric plants operated by factories, hotels, etc., which 

 consume the current generated; those operated by the Federal 

 Government and State institutions; or plants that were idle or 

 in course of construction. 



Aside from the growth in the number of stations the striking 

 features of the above table are the relatively larger increase in 

 the kilowatt capacity per station, while the cost of construction 

 and equipment remains practically the same. That this cost 

 has not been materially reduced is no doubt due to the increased 

 cost of the distributing and transmission lines, which form an 

 important part of the total cost of the system. 



It is also of interest to note that the percentage increase in 

 the use of water power for the period of 1902 to 1912 was 463 per 

 cent, as compared to 254 per cent for steam power. On the 

 other hand, gas power increased 811 per cent, but this is not 

 of any great importance, as the horse-power capacity of the 

 gas engines installed at the beginning of above period was very 

 small. 



Water power was used more extensively than steam in the 

 manufacturing industry prior to 1870. Since that time, however, 

 it declined steadily, while the use of steam power increased, 

 reaching a maximum of about 87 per cent in 1900. There has 

 since been a marked falling off in the percentage of directly applied 

 steam power and this has been due to the rapid introduction of 

 electric power. The increased use of the electric motor for driving 

 industrial machinery has been phenomenal and this is again best 

 illustrated by a reference to the Census Report. 



Table VIII shows for all industries combined the horse- 

 power of engines and motors employed by manufacturing con- 

 cerns for the period from 1870 to 1909. The figures for the total 

 primary power exclude duplication and represent the primary 

 power of engines, water wheels, etc., owned by the manufacturing 

 establishments themselves plus the electric and other power pur- 

 chased from outside concerns. Especially striking is the increased 

 use of electric motor applications during this period. While the 

 primary power increased about 85 per cent, the application of 

 electric motors for manufacturing industries alone increased close 

 to 900 per cent. 



