2i6 EDWARD H. SANBORN 



reduced by the large number of small engines which are used 

 for auxiliary purposes in every iron and steel plant. 



The decade between 1890 and 1900 was a period of 

 marked development in the use of gas engines, using that term 

 to denote all forms of internal combustion engines, in which 

 the propelling force is the explosion of gaseous or vaporous 

 fuel in direct contact with a piston within a closed cylinder. 

 This group embraces those engines using ordinary illuminating 

 gas, natural gas, and gas made in special producers installed 

 as a part of the power plant, and also vaporized gasoline or 

 kerosene. This form of power appears for the first time as 

 an item of consequence in the returns of the last census, and 

 the very large increase in the horsepower in 1900 as compared 

 with 1890 indicates the growing popularity of this class of 

 motive power. 



In 1890 the number of gas engines in use in manufactur- 

 ing plants was not reported, but their total power amounted 

 to only 8,930 horsepower, or one tenth of 1 per cent of the 

 total power utilized in manufacturing operations. In 1900, 

 however, 14,884 gas engines were reported, with a total of 

 143,850 horsepower, or 1.3 per cent of the total power used 

 for manufacturing purposes. This increase from 8,930 horse- 

 power to 143,850 horsepower, a gain of 134,920 horsepower, 

 is proportionately the largest increase in any form of primary 

 power shown by a comparison of the figures of the eleventh 

 and twelfth censuses, amounting to 1,510.9 per cent. 



Within the past decade, and more particularly during 

 the past five years, there has been a marked increase in the 

 use of this power in industrial establishments for driving ma- 

 chinery, for generating electricity, and for other kindred uses. 

 At the same time, internal combustion engines have increased 

 in popularity for uses apart from manufacturing, and the 

 amount of this kind of power in use for all purposes in 1900 

 was, doubtless, very much larger than indicated by the figures 

 relating to manufacturing plants alone. 



The average horsepower per gas engine in 1900 was 9.7 

 horsepower. There are no available statistics upon which 

 to base a comparison of this average with the average for 

 1890, but it is doubtful if there has been any very material 



