born June 10, 1832, Holzhausen, Nassau
died Jan. 26, 1891, Cologne, Ger.
German engineer who developed the four-stroke internal-combustion engine .
He built his first gasoline-powered engine in 1861, and in 1876 he built an internal-combustion engine using the four-stroke cycle (four strokes of the piston for each explosion), which offered the first practical alternative to the steam engine as a power source. Though the four-stroke cycle was patented in 1862 by Alphonse Beau de Rochas (181593), it is commonly known as the Otto cycle since Otto was the first to build such an engine.