Denis Papin was an assistant of Huygens. Huygens showed him the gunpowder-engine. The power of this engine was not effective. Papin could at least make the operation of the engine more secure with his invention of a touch-pan. However, the engine firing off was still very dangerous because its material could hardly stand the huge explosions. Papin then thought of his knowledge of water. He knew that water can get "as elastic as air" and also knew that this procedure could be reversed. Therefore, he wanted to create an engine that could produce the "entire emptiness".
Papins atmospheric piston engine
The cylinder was filled up halfway with water before the piston is pushed down to the water. The air can escape through a small tube. If the whole cylinder is heated, the water converts into steam; the steam presses the piston up. In the highest position, a fastener grabs the piston and holds it at the head. When the steam condenses, the atmospheric pressure will press the piston back down. The power stroke does not occur during the vaporizing but during the condensation of steam. Papin intended to lift a weight with a cord over a spool. He calculated that an engine with a piston of 24 inches in diameter and a stroke of 4 feet could lift a weight of 3.5 tons. This would be equal to 1 Horsepower.
His engine was not at all satisfying. The power was limited, because all functions have been inside of one tool (boiler, cylinder, piston)that had to be heated and cooled. Furthermore, the engine was only cooled with fresh air. Papin also invented a geared piston bar, which could turn a cogwheel while the piston slided downward during the work period of the engine. But he could not manage the construction because of his insufficient technical knowledge. There was no hand worker that could produce an example of the engine and his own knowledge was only sufficient for his labour. Papin was more successful in inventing other different things besides steam power.
Some years later, Papin received an order from the count of Kassel. He was asked to build an engine that could lift water to a defined height. The count paid all the covers. Papin developed in his engine some interesting technical details. He used a free-swimming piston which prevented the steam from condensing on the cold water-surface. Furthermore, he invented a safety valve that limited the maximal steam-pressure. Unfortunately, the joints and valves were leaking so the count lost the interest in Papins steam engine and researches.
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