50 CONTEMPORARY SCIENCE 



and the cost of deepening the harbors that limit the size 

 of Atlantic liners. 



Such developments generally take place slowly, other- 

 wise failures occur as in the case of the Great Eastern 

 and it may be many years before the airship is increased 

 from the present maximum of 750 feet to 1,500 feet with 

 success, but it will assuredly come. If, however, the de- 

 velopment is subsided or assisted by government in- 

 cidental failures may be faced with equanimity and very 

 rapid development accomplished. 1 In peace time the sea- 

 plane, aeroplane, and airship will most certainly have 

 their uses. But, except for special services of high utility, 

 it is questionable whether they will play more than a 

 minor part as compared with the steamship, railway, and 

 motor transport. 



Electricity. The supply and use of electricity has de- 

 veloped rapidly in recent years. For lighting it is the rival 

 of gas, though each has its advantages. As a means of 

 transmitting power over long distances it has no rival, 

 and its efficiency is so high that when generated on a 

 large scale and distributed over large areas it is a cheap 

 and reliable source of power for working factories, tram- 

 ways, suburban railways, and innumerable other pur- 

 poses, including metallurgical and chemical processes. It 

 is rapidly superseding locally generated steam-power, and 

 is a rival to the small and moderate-sized gas and oil 

 engine. It has made practicable the use of water-power 

 through the generation of electricity in bulk at the natural 

 falls, from which the power is transmitted to the consum- 

 ers, sometimes at great distances. 



Fifteen years ago electricity was generated chiefly by 

 large reciprocating steam engines, direct coupled to dyna- 

 mos or alternators, but of late years steam turbines have 

 in most instances replaced them, and are now exclusively 

 used in large generating stations, because of their smaller 



1 The literature on this subject includes an article which ap- 

 peared in Engineering on January 3, 1919. 



