POWER EMPLOYED IN MANUFACTURES 211 



facturing as a basis upon which to make calcuhitions concern- 

 ing the aggregate power requirements of the country. 



A few decades ago the use of power in any considerable 

 quantity w^as Hmited practically to manufacturing operations. 

 Within the past twenty years, and more particularly during 

 the last decade, the use of electricity for lighting and for the 

 operation of street railways has developed enormously, and 

 has resulted in the utilization of power in an entirely new field 

 to an extent that exceeds the total amount of power used in 

 man}^ of the larger manufacturing industries. 



During 1900 over 1,200 electric railway lines w^ere in 

 operation in the United States, and the total capacity of their 

 power plants exceeded 1,000,000 horsepower. There are 

 over 3,300 central stations for the distribution of electric 

 current for lighting and power purposes, and the total amount 

 of steam power used to generate it is estimated to be more 

 than 1,500,000 horsepower. One company alone, in New 

 York city, operates several central stations, aggregating 

 nearly 250,000 horsepower. Independent isolated electrical 

 plants, which furnish light and powder for stores, office build- 

 ings, hotels, pubUc buildings, etc., constitute another item 

 of power of great magnitude. There are no data available 

 for even approximating the amount of powder thus utilized 

 in the entire United States; but a recent canvass of New 

 York city by one of the electrical companies showed that the 

 isolated electrical plants in that city represented over 100,000 

 horsepower thus applied. 



The modern office building, often housing a population 

 equal to that of a small town, is almost wholly a creation of 

 the past fifteen j^ears, and the power required in these great 

 structures, not only for lighting purposes, but for the opera- 

 tion of elevators, pumping water, compressing air, and oper- 

 ating refrigerating and ventilating machinery, forms a large 

 item w^ien the number of these buildings in the United States 

 is taken into consideration. 



As illustrative of this, the power plant of one sixteen 

 story modem building, containing 560 offices, may be of in- 

 terest. In this building there are 4 engines, 3 of 150 horse- 

 power each, and 1 of 75 horsepower, which are used to drive 



