Newcomen's Steam Engine

Thomas Newcomen (1663-1729), English inventor of an early atmospheric steam engine (c.1712). The steam engine was an improvement over an earlier engine patented in 1698 by Thomas Savery, who later shared the patent with Newcomen. The engine was used for pumping water out of mines in Newcomen's native southwest England, particularly in Cornwall. Engines were installed by Newcomen himself in mines in the Midlands, north Wales, and Cumbria, with over 100 built before the patent expired in 1733. They were called "atmospheric" engines because the greatest steam pressure used was near atmospheric pressure. His first working engine had a cylinder 21 inches in diameter and nearly eight feet long, worked at twelve strokes a minute, raising ten gallons of water from a depth of 156 feet, and had approximately 5.5 horsepower. The engines were rugged and reliable and worked day and night but were less than one percent efficient, using large amounts of coal, and were consequently first installed in coal mines. Newcomen's design would later be improved by James Watt.