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James WattJames Watt

steam engine builder

James Watt was born in Greenock, Scotland, on January 19, 1736, the son of a shipowner and ship-builder. When he was 18, he went to Glasgow and then to London to learn the trade of a mathematical instrument maker. In 1757, he became instrument maker at the University of Glasgow.

In 1763, Watt received a model of a Newcomen Steam Engine to repair. While doing the repairs he became determined to improve upon the engine's design. After obtaining advice from students and colleagues at the university, Watt discovered the principle of the separate condenser; he patented his discovery in 1769 as a "new method of lessening the consumption of steam and fuel in fire engines."

diagram of Watt's patent rotative steam engineIn the Newcomen engine, steam filled the cylinder space under the piston. The steam was then condensed, leaving a vacuum into which the piston was pushed by atmospheric pressure. This meant alternately heating and chilling the cylidner. Watt reasoned that because steam was an elastic vapor, it would fill any container into which it was admitted. If the steam-filled cylinder opened into a separate, chilled container, steam would continually move into the container and condense there, producing the vacuum in the cylinder without having to chill it.

left: diagram of Watt's patent rotative steam engine

Watt spent several years trying to develop an operating engine of his design, during which period he also worked as a surveyor and construction engineer to help pay his bills. In 1774, he obtained the support of Matthew Boulton, a Birmingham manufacturer. Boulton persuaded Parliament to renew Watt's patent for another 25 years. The two then organized a company to rent the design of Watt's engine and to supervise its construction. The firm succeeded.

Watt's steam-heat coilsOnce his basic engine had been perfected, Watt proceded to develop crank movements so the engine could turn wheels. This one improvement to his steam engine may very well have been the single most important advance that made the Industrial Revolution possible. He also invented an "expansive, double-acting" piston in which steam is alternately fed into each end of the cylinder, increasing its working capacity; a throttle valve; a governor that automatically controlled the speed of the engine by regulating the steam flow; a pressure gauge; and, many other devices. In 1784, he installed steam coils in his office to provide heat -- the first practical use of steam for heating.

right: Watt's steam-heat coils

Watt also did research in chemistry and metallurgy, and was one of the first persons to suggest that water is a compound, not an element. His other inventions included the office copying press, which used a special ink to record copies of correspondence and invoices in a ledger, and a device to reproduce sculptured busts.

In 1785, both Watt and Boulton were elected Fellows of the Royal Society. Watt retired as a wealthy man in 1800, and died on August 25, 1819. He is buried at Handsworth Church near Birmingham, next to his business partner.

The Watt, a unit of power, is named in his honor.

Newcomen Steam Engine
Matthew Boulton

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The Robinson Library >> Technology >> Engineering (General)

This page was last updated on January 18, 2017.