Thomas Newcomen (1663-1729)
Illustration of Thomas Newcomen's Engine 1712
Thomas Newcomen was an English blacksmith, who invented the atmospheric steam engine, an improvement over Thomas Slavery's previous design.
The Newcomen steam engine used the force of atmospheric pressure to do the work. Thomas Newcomen's engine pumped steam into a cylinder. The steam was then condensed by cold water which created a vacuum on the inside of the cylinder. The resulting atmospheric pressure operated a piston, creating downward strokes. In Newcomen's engine the intensity of pressure was not limited by the pressure of the steam, unlike what Thomas Savery had patented in 1698.
In 1712, Thomas Newcomen together with John Calley built their first engine on top of a water filled mine shaft and used it to pump water out of the mine. The Newcomen engine was the predecessor to the Watt engine and it was one of the most interesting pieces of technology developed during the 1700's.
The Savery steam engine could not be improved to solve the problem of water pumping. A new design and principle of operation was required.
Thomas Newcomen provided that design. Newcomen was a merchant, an iron monger who dealt in metal parts and bulk iron. He dealt with the needs of the mines in southwest Britain and knew of need for pumps in the deep mines. He also fabricated equipment for his customers. His assistant and partner, Cawley, was a plumber. Between the two of them they uniquely had the skills required to fabricate a pump operated by steam power. Other more learned men attacked the problem but did not have the practical skills that Newcomen had. In effect, Thomas Newcomen was a businessman-engineer, just what was needed to solve the problem.
The way the Newcomen engine work, as is illustrated below, what with a piston in a cylinder connected to a rocker arm attached to a pump. first the cylinder was filled with steam from a boiler. This pushed the piston up. Then water was sprayed into the cylinder creating a vacuum. This pushed the piston down pulling the pump rod on the other side of the rocker arm up, thus lifting the water.
The opening and closing of valves for the alternating injection of steam and water was self-actuating so the engine and pump could operate continuously.
The Newcomen engine solved the problem of pumping water from the deep mines. Despite a high cost of £1000 about 1500 were put into operation. Many of these Newcomen engines were built after the invention of the Watt engine.