James Watt
James Watt made the steam engine efficient enough to power an industrial revolution. Born in Greenock in 1736, the son of a shipwright and merchant, he was a sickly child taught largely at home, showed exceptional manual skill, and trained as an instrument maker in London before setting up at the University of Glasgow, where the trade guilds could not exclude him. In 1763 he was given a model Newcomen engine to repair and found that it worked appallingly. The Newcomen design condensed steam inside the cylinder by injecting cold water, which meant the cylinder was chilled on every stroke and had to be reheated, wasting most of the fuel. Walking on Glasgow Green in 1765 he saw the answer: condense the steam in a separate vessel connected by a valve, so that the cylinder stays hot permanently. It cut coal consumption by about three quarters. Turning that into a manufactured product took another decade and required Matthew Boulton's capital, John Wilkinson's cannon-boring machinery for accurate cylinders, and an act of parliament extending the patent to 1800. He then added the developments that made it general rather than a pumping engine: sun-and-planet gearing to give rotary motion, the double-acting cylinder, the parallel motion linkage, the centrifugal governor, and a pressure indicator. He and Boulton sold engines on a royalty based on the coal saved. He also coined the term horsepower to sell against horses, and the unit of power is named after him. He defended his patents aggressively, which some argue delayed high-pressure engines. He died in 1819. He is buried at Handsworth beside Boulton.
- Lived: 1736 CE – 1819 CE
- Nationality: Scottish
- Roles: inventor, engineer
