Otto gas engine, 1876.
© Science Museum / Science & Society Picture Library
Nikolaus August Otto (1832-1891) gave his name to the four-stroke engine cycle which he developed with Eugen Langen (1833-1895) in 1876. The Otto cycle begins when an explodable mixture of gas and air is drawn into the cylinder by the piston (the induction stroke), compresed (the compresion stroke), and ignited (the combustion stroke) - the expanding gases providing the power to drive the piston - and the burned gases are then driven out of the cylinder (the exhaust stroke). This example was manufactured in Manchester by Crosley Ltd.