18th Century Pioneer

James Watt (1736 – 1819)

Born in Scotland, the son of a successful ship and house builder.  His steam engine provided the horsepower to turn the 19th century electricity generators.  The unit of power, the Watt, was named to honor him.

He was a mathematical instrument maker in his youth, a surveyor and inventor.  While repairing a Newcomen steam engine (they were used to pump water out of coal mines), he discovered a more efficient way to utilize steam wasted in the Newcomen engine.  He developed a separate condenser that improved its performance.  Later on he developed a test engine, with the financial help of a friend, named Joseph Black.  His method for using steam as power was patented in 1769; titled “A New Invented Method of Lessening the Consumption of Steam and Fuel in Fire Engines”. 

Inventions followed with a sun-and planet-gear in 1782, a double-acting engine that increased performance, a centrifugal governor that controlled speed of the engine and a pressure gauge to monitor steam pressure.  By 1790, his Watt engine was complete.  It was used in many applications where mechanical power was required.

The term horsepower is due to Watt’s using it as a power rating for his engines.  He figured horsepower to represent the power of a strong dray horse doing work over a short time interval.

By todays measurement standards, 1 horsepower is equal to 746 watts.

Reference: Encyclopedia Britannica