Engine of Progress

Diesel's machine relies on internal combustion, but lacks a carburetor to premix air and fuel and spark plugs to ignite the mixture. Instead, air in the cylinder is compressed to high pressure and temperature, and injected fuel ignites spontaneously. By the 1920s, the popular diesel engine had reached the United States, and by the 1950s, a large proportion of the world's ships and trains were diesel driven, with trucks, tractors, and buses following close behind.

[Source: Roy Porter, Ed., The Biographical Dictionary of Scientists (Oxford University Press, ed. 2, 1994).]