out that it did not actually compress the fuel-air mixture, it simply moved the fresh mixture to the working cylinder to force out the gasses burnt previously. Clerk's engine vs modern two-stroke engine Clerk's original design did not allow the construction of smaller engines, as it required the aforementioned additional pumping cylinder for each working cylinder. The crucial simplification of the concept, that made possible small yet powerful two-stroke engines for mass markets, was patented by Joseph Day in 1894. Joseph Day, design of a three-port two-stroke engine Nash, design of a two-port two-stroke engine Robson, design of a two-stroke engine with under-piston scavenge Fielding, design of a uniflow two-stroke engine Arms See also Joseph Day History of the internal combustion engine Bibliography References External links 1854 births 1932 deaths Knights Commander of the Order of the British Empire People associated with the internal combustion engine Scottish inventors Royal Medal winners Fellows of the Royal Society Engineers from Glasgow Alumni of the University of Strathclyde Alumni of the University of Leeds Scottish engineers British mechanical engineers