PAPIN, DENIS (1647–c. 1712), French physicist, one of the inventors of the steam-engine, was born at Blois on Aug. 22, Papin acted as assistant to Huygens (q.v.) in his experiments with the air pump. Later he came to London and assisted Boyle. He introduced a number of improvements in the air pump and invented the condensing-pump. In 1679 he invented his famous "steam digester," a vessel with a tightly fitting lid which prevented the steam (from water heated in it) escaping, and thus a high pressure was generated and the boiling point of the water con siderably raised. A safety valve guarded against excessive rise of pressure. In 1684 Papin received from the Royal Society an appointment as "temporary curator of experiments," with a small salary. In this capacity he carried on numerous and varied investigations in hydraulics (Phil. Trans., 1685, etc.). In Nov. 1687 he was appointed to the chair of mathematics in the Uni versity of Marburg, and here he remained until 1696, when he removed to Cassel. In 1705 Leibnitz sent him a sketch of Savery's
engine for raising water, and this stimulated him to further exer tions, which resulted two years afterwards in the publication of the Ars nova ad aquam ignis adminiculo efficacissime elevandam (Cassel, 1707). (See STEAM ENGINE.) In 1707 Papin returned to London where he died in obscurity, probably early in 1712.