John Stringfellow (1799-1883) was a designer and builder of steam power plants. A short time after William Henson patented his design for the Henson Aerial Steam Carriage in 1842, Stringfellow became his associate and was responsible for the engine. Between 1944 and 1847, a number of models were made, but they were not successful; Henson lost interest and moved to the United States. Stringfellow and his son Frederick J. Stringfellow later collaborated with steam engine experiments and built a number of flying machines together and individually. Perhaps the most famous of John Stringfellow's machines was his Stringfellow 1868 Steam-Powered Triplane, which was exhibited at the Crystal Palace in London, England. For this one-horsepower engine, Stringfellow was awarded a prize of 100 pounds, as it was judged the lightest engine in proportion to its power. At the time of the Exhibition, the engine featured a double piston but after the competition, Stringfellow modified the engine to have a single piston rod drive with a pulley arrangement. In 1889, the Stringfellow engine became the first object accessioned into the National Air Museum's collection and is currently on display in the Early Flight Gallery of the National Air & Space Museum, Washington, DC.