Denis Papin (22.08.1647-1712) was a physicist and engineer, one of the inventors of the steam engine, a Fellow of the Royal Society (1680) and a member of the Paris Academy of Sciences. Born in Chitenay near Blois (France). Graduated from the University of Angers (1669) and was an assistant to C. Huygens at the Paris Academy of Sciences. In 1675 he moved to London, where in 1676–79 he was an assistant to R. Boyle. In 1680 he was in Paris, in 1681–84 in Venice, in 1684–87 curator of the experiments carried out at the Royal Society, and in 1687–95 professor at the University of Marburg (Germany).
His work concerned heat, hydraulics and pneumatics. In 1674, with C. Huygens, he improved the air pump and carried out a number of studies with it, discovered the dependence of the boiling point of water on pressure, establishing that at lower pressure water boils at a temperature below 100 °C. He invented the steam digester (1680), fitting it in 1681 with a safety valve. In 1690 he was the first to use steam to raise a piston and described the closed thermodynamic cycle of a steam engine, and in 1707 he presented a description of his engine (Papin's steam engine). Together with R. Boyle and F. Hauksbee he proved that air is a conductor of sound. He was the author of a number of inventions.