Denis Papin (August 22, 1647 - 1712) was a French physicist, mathematician and inventor. Papin invented the first steam digester, a type of pressure cooker with a safety valve, pictured here (1681). Papin also built a model of a piston steam engine, the first of its kind. In 1704, he constructed a ship powered by his steam engine, mechanically linked to paddles. This made him the first to construct a steam-powered boat (or vehicle of any kind). In 1705 he developed a second steam engine with the help of Gottfried Leibniz, based on an invention by Thomas Savery, but this used steam pressure rather than atmospheric pressure.