Watt, James

Watt, James, 1736–1819, Scottish inventor. While working at the Univ. of Glasgow as an instrument maker, Watt was asked to repair a model of Thomas Newcomen's steam engine. He devised improvements that resulted in a new type of engine (patented 1769) with a separate condensing chamber, an air pump to bring steam into the chamber, and parts of the engine insulated. He also perfected a rotary engine. Matthew Boulton financed Watt's work and was his partner (1775–80) in manufacturing the engines at Soho near Birmingham. Watt coined the term horsepower. The watt, a unit of electrical power, was named for him.

Bibliography

See his correspondence, Partners in Science, ed. by E. H. Robinson and D. McKie (1970); study by E. H. Robinson and A. E. Musson (1969).

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Watt, James

James Watt, oil painting by H. Howard; in the National Portrait Gallery, London.

(credit: Courtesy of The National Portrait Gallery, London)

(born Jan. 19, 1736, Greenock, Renfrewshire, Scot.—died Aug. 25, 1819, Heathfield Hall, near Birmingham, Warwick, Eng.) Scottish engineer and inventor. Though largely self-taught, he began work early as an instrument maker and later as an engineer on the Forth and Clyde Canal. Watt's major improvement to Thomas Newcomen's steam engine was the use of a separate condenser (1769), which reduced the loss of latent heat and greatly increased its efficiency. With Matthew Boulton he began manufacture of his new engine in 1775. In 1781 he added rotary motion (a so-called sun-and-planet gear) to replace the up-and-down action of the original engine. In 1782 he patented the double-acting engine, in which the piston pushed as well as pulled. This engine required a new method of rigidly connecting the piston to the beam, a problem he solved in 1784 with an arrangement of connected rods that guided the piston rod in a perpendicular motion. His application of the centrifugal governor for automatic control of the speed of the engine (1788) and his invention of a pressure gauge (1790) virtually completed the Watt engine, which had immense consequences for the Industrial Revolution. He introduced the concept of horsepower; the watt, a unit of power, is named for him.

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Watt, James 

Born Jan. 19, 1736, in Greenock, Scotland; died Aug. 19, 1819, in Heathfield, England. British inventor of the universal steam engine. Member of the Royal Society of London (1785).

Beginning in 1757, Watt worked as a scientific instrument-maker at the University of Glasgow, where he became familiar with the properties of steam and, using D. Papin’s boiler, undertook a careful study of the dependence of the temperature of saturated vapor on pressure. In 1763–64, while working on a model of the steam engine designed by T. Newcomen, Watt concluded that the large consumption of steam in the engine was caused by the cooling of the cylinder walls down to the temperature of the cooling water as it entered the cylinder. He theorized that steam consumption could be reduced by separating the steam condenser from the cylinder, and in 1765 he built an experimental engine with a cylinder diameter of 16 cm, and, in 1768, the first large steam engine. The latter, however, proved to have a number of defects—the condenser was not successful, and the piston required additional sealing. In 1769, Watt obtained a British patent for methods of reducing steam consumption and, consequently, fuel in combustion engines. The patent covered a number of new technical proposals, such as the use of a steam jacket for maintaining temperature in the cylinder and a design for a rotary steam engine. Actual construction of the steam engine was completed in 1774, and subsequent tests showed that Watt’s engine was more than twice as efficient as the best Newcomen engines. In order to ensure steady engine operation, Watt used a centrifugal governor connected to a gate valve on the outlet steam pipe. Watt retained the balance wheel as the driving gear but used the sun and planet gear to double the speed of shaft rotation. He thoroughly investigated steam operation in the cylinder and was the first to design an indicator for this purpose. In 1782 he obtained a British patent for an engine that used steam expansively. Watt introduced the first unit of power—the horsepower—and his own name later came to designate a second unit of power—the watt.

Because of its efficiency, Watt’s steam engine became widely used and played an enormous role in the transition to mechanical production. “The great genius of Watt, ” wrote K. Marx, “lies in that fact that, in the patent he obtained . . ., his steam engine is not presented as an invention for specific purposes only, but as a universal engine for heavy industry” (K. Marx and F. Engels, Soch., 2nd ed., vol. 23, p. 389).

After 1784, Watt was primarily concerned with improving the manufacture of steam engines at his plant.

REFERENCES

Radtsig, A. A. Dzhems Uatt i izobretenie parovoi mashiny. Petrograd, 1924.
Konfederatov, I. Ia. Dzhems Uatt—izobretatel’ parovoi mashiny. Moscow, 1969.

I. IA. KONFEDERATOV