Joseph Day (inventor)

Joseph Mary Day (1855 to 1946) was an English engineer who invented the valveless three-port two-stroke engine. Born in Bayswater, London, the son of a judge, he trained at the School of Practical Engineering at the Crystal Palace, worked at Stothert and Pitt in Bath, and in 1878 started an iron foundry in Bath with J. W. Lampard. By 1889 he was working on an engine design that would avoid Otto's four-stroke patents, and he applied for a patent in April 1891. In 1892 his workman Frederick Cocks made the modification that let the piston skirt control the inlet port, removing the valves and giving the classic piston ported two-stroke, patented in October 1892. Day went bankrupt in 1893, but American licence holders, including Palmers of Connecticut, which built more than 60,000 engines before 1912, carried the design on, and many of those engines went into motorcycles and boats. He opened the Day Motor Co in 1906 and died in 1946 aged 91.