Although the company supplying electricity to a house charges by the kilowatt hour, and electric bulbs have a W on them to indicate power output, the greatest contribution of James Watt was not in the field of electricity but rather in the improvement of the engine that has given the world the practical power of steam.
Watt (1736-1819) was born in Greenock, Scotland. In grammar school he learned Latin, Greek, and mathematics. Watt had a natural curiosity for things mechanical. Repairing any kind of machinery gave him pleasure, and he became a maker of mathematical instruments such as quadrants, scales, and compasses. Through a stroke of good fortune, in 1757 he was named mathematical instrument maker to the College of Glasgow, a prestigious title for a man who had barely reached twenty years of age.
The decisive event that set the course of Watt’s life came when he was asked to repair a model of Newcomen’s steam engine the best-known engine at that time for pumping water from coal mines. This engine used an enormous amount of steam and therefore large amounts of fuel. Watt separated the condenser and the cylinder, keeping the cylinder hot at all times and saving three fourths of the fuel. By reducing the cost of operating this engine, Watt made it practical for other uses.
The story that made the rounds is that Watt got his idea while watching a kettle boiling on the fire at his home. His aunt rebuked him for fiddling with the kettle — holding a spoon over the spout, releasing it, and then holding it again. She suggested that he spend his time doing something more useful.
After Watt left the college, he became a partner with an engineer from Birmingham, Matthew Boulton. The company was successful, enabling Watt to devote time to other inventions — a throttle value, a governor to regulate the speed of steam engines, a smoke-consuming furnace, a machine to reproduce sculpture, and a copying press, among other devices. Watt and Boulton coined the word horsepower.
In 1885, the International Electrical Congress honored Watt by naming the watt as a unit of electrical power — 736 watts being equal to about one horsepower. The honor was not bestowed for his contribution to the modem science of electricity but for his contributions to applied science. He was considered the greatest single impetus behind the Industrial Revolution.