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In page Denis Papin:

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While in Marburg in 1690, having observed the mechanical power of atmospheric pressure on his 'digester', Papin built a model of a piston steam engine, the first of its kind. In 1705 while teaching mathematics at the University of Marburg,[4] he developed a second steam engine with the help of Gottfried Leibniz, based[citation needed] on an invention by Thomas Savery, but this used steam pressure rather than atmospheric pressure. Details of the engine were published in 1707.