Clerk, Dugald (1854–1932)
Scottish engineer who invented the Clerk cycle or two-stroke
cycle, which he patented in 1881. It is much used on lightweight
motorcycles, lawn mowers, and outboard motors on small boats. Director of
engineering research for the British Admiralty 1916, he wrote The Gas,
Petrol, and Oil Engine (2 vols, 1909 and 1913).