The effect of introducing liquid fuel and of mechanical stokers for coal, in electric power plants, and on steamships, was to emancipate a race of galley slaves, the stokers, those miserable driven men whose cruel work Eugene O’Neill properly took as the symbol of proletarian oppression in his drama, The Hairy Ape. Meanwhile, the efficiency of the steam engine was raised: the invention of Parson’s steam turbine in 1884 increased the efficiency of the steam  engine from ten or twelve for the old reciprocating engine to a good thirty per cent for the turbine, and the later use of mercury vapor instead of steam in turbines raised this to 41.5 per cent. How rapid was the advance in efficiency may be gauged from the average consumption of coal in power stations: it dropped from 3.2 pounds per kilowatt hour in 1913 to 1.34 pounds in 1928. These improvements made possible the electrification of railroads even where cheap water power could not be secured. (Mumford 1934:235-6)
MUMFORD, Lewis. 1934. Technique and civilization. New York: Harcourt, Brace and Company.