The Newcomen steam engine used the force of atmospheric pressure to do the work. This process begins with the engine pumping steam into a cylinder. The steam was then condensed by cold water, which created a vacuum on the inside of the cylinder. read more
James Watt, in 1781, patented a steam engine that produced continued rotary motion with a power of about 10 horsepower (7,500 W). It was the first type of steam engine to make use of steam at a pressure just above atmospheric to drive the piston helped by a partial vacuum. It was an improvement of Newcomen's engine. read more