Watt, James

SUBJECT AREA: Steam and internal combustion engines

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b. 19 January 1735 Greenock, Renfrewshire, Scotland

d. 19 August 1819 Handsworth Heath, Birmingham, England

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Scottish engineer and inventor of the separate condenser for the steam engine.

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The sixth child of James Watt, merchant and general contractor, and Agnes Muirhead, Watt was a weak and sickly child; he was one of only two to survive childhood out of a total of eight, yet, like his father, he was to live to an age of over 80. He was educated at local schools, including Greenock Grammar School where he was an uninspired pupil. At the age of 17 he was sent to live with relatives in Glasgow and then in 1755 to London to become an apprentice to a mathematical instrument maker, John Morgan of Finch Lane, Cornhill. Less than a year later he returned to Greenock and then to Glasgow, where he was appointed mathematical instrument maker to the University and was permitted in 1757 to set up a workshop within the University grounds. In this position he came to know many of the University professors and staff, and it was thus that he became involved in work on the steam engine when in 1764 he was asked to put in working order a defective Newcomen engine model. It did not take Watt long to perceive that the great inefficiency of the Newcomen engine was due to the repeated heating and cooling of the cylinder. His idea was to drive the steam out of the cylinder and to condense it in a separate vessel. The story is told of Watt's flash of inspiration as he was walking across Glasgow Green one Sunday afternoon; the idea formed perfectly in his mind and he became anxious to get back to his workshop to construct the necessary apparatus, but this was the Sabbath and work had to wait until the morrow, so Watt forced himself to wait until the Monday morning.

Watt designed a condensing engine and was lent money for its development by Joseph Black, the Glasgow University professor who had established the concept of latent heat. In 1768 Watt went into partnership with John Roebuck, who required the steam engine for the drainage of a coal-mine that he was opening up at Bo'ness, West Lothian. In 1769, Watt took out his patent for "A New Invented Method of Lessening the Consumption of Steam and Fuel in Fire Engines". When Roebuck went bankrupt in 1772, Matthew Boulton, proprietor of the Soho Engineering Works near Birmingham, bought Roebuck's share in Watt's patent. Watt had met Boulton four years earlier at the Soho works, where power was obtained at that time by means of a water-wheel and a steam engine to pump the water back up again above the wheel. Watt moved to Birmingham in 1774, and after the patent had been extended by Parliament in 1775 he and Boulton embarked on a highly profitable partnership. While Boulton endeavoured to keep the business supplied with capital, Watt continued to refine his engine, making several improvements over the years; he was also involved frequently in legal proceedings over infringements of his patent.

In 1794 Watt and Boulton founded the new company of Boulton \& Watt, with a view to their retirement; Watt's son James and Boulton's son Matthew assumed management of the company. Watt retired in 1800, but continued to spend much of his time in the workshop he had set up in the garret of his Heathfield home; principal amongst his work after retirement was the invention of a pantograph sculpturing machine.

James Watt was hard-working, ingenious and essentially practical, but it is doubtful that he would have succeeded as he did without the business sense of his partner, Matthew Boulton. Watt coined the term "horsepower" for quantifying the output of engines, and the SI unit of power, the watt, is named in his honour.

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Principal Honours and Distinctions

FRS 1785. Honorary LLD, University of Glasgow 1806. Foreign Associate, Académie des Sciences, Paris 1814.

Further Reading

H.W.Dickinson and R Jenkins, 1927, James Watt and the Steam Engine, Oxford: Clarendon Press.

L.T.C.Rolt, 1962, James Watt, London: B.T. Batsford.

R.Wailes, 1963, James Watt, Instrument Maker (The Great Masters: Engineering Heritage, Vol. 1), London: Institution of Mechanical Engineers.

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