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James Watt

This article is about the Scottish engineer and inventor. For Ronald Reagan's Secretary of the Interior, see James G. Watt.

James Watt (January 19, 1736 - August 19, 1819) was a Scottish mathematician and engineer.

He was born in Greenock, Scotland, and lived and worked in Birmingham. He was a key member of the Lunar Society. Many of his papers are in Birmingham Central Library.


Engineering Achievements

Watt invented the centrifugal governor to regulate the speed of a steam engine. The parallel motion to convert circular motion to an approximate straight line motion (of which he was most proud) and the steam indicator to measure steam presure in the cylinder throughout the working cycle of the engine.

Watt greatly helped the development of the embryonic steam engine into a viable and economic means of power generation. He realised that the Newcomen steam engine was wasting nearly three quarters of the steam energy in heating the piston and chamber. Watt developed a separate condenser chamber which significantly increased the efficiency. Further refinements made the steam engine his life's work.

He introduced a unit called the horsepower to compare the power output of steam engines, his version of the unit being equivalent to 550 foot-pounds per second (about 745.7 watts).

The SI unit of power, the watt, is named after him. So is, at least in part, Edinburgh's Heriot-Watt University.

He is also remembered by the Moonstones, two individual statues, and a statue of him, Boulton,and Murdoch, by William Bloye, all in Birmingham. There are also over 50 roads or streets named after him, in the UK.