Papin, Denis, 1647-1712?, French physicist and inventor. He was an assistant of Christian Huygens and of Robert Boyle and was professor of mathematics at the Univ. of Marburg (1687-96). He invented (1679) a steam digester (forerunner of the autoclave), a vessel in which the boiling point of water is raised by an increase in steam pressure; this device demonstrated the influence of atmospheric pressure on boiling points. His other inventions include a safety valve (for the digester), a condensing pump, an air gun, and a paddle-wheel boat. A pioneer in the development of the steam engine, he devised in 1690 a pump with a piston raised by steam.