Newcomen, Thomas

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Newcomen, Thomas (1663–1729). Dartmouth ironmonger and inventor of the atmospheric steam-engine. He combined Savery's independent boiler with the piston in his first ‘fire engine’ of 1712 at Dudley, applying atmospheric pressure to the top of the cylinder in which steam was condensed to create a partial vacuum and drive down the piston linked by chain to the beam that transmitted the stroke to pumps. Its use was confined to pumping water from mines or to supply networks; diffusion was limited by under-boilering and the extension of Savery's generic patent to 1733, but extended to Wales, the midlands, and the Newcastle collieries; up to 60 had been installed by 1733, the best producing a duty (pounds of water raised one foot by a bushel of coals) of 3.75 million, but a lift of under 45 yards. Smeaton's improvements allowed such engines to supply most horsepower c.1800, and Thompson's patent (1792), effective rotary motion.

J. A. Chartres

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