'Lesening the consumption of steam and fuel in fire engines', 1769.
© Science Museum / Science & Society Picture Library
Title page of Watt's patented method for 'lesening the consumption of steam and fuel in fire engines', 1769. James Watt (1736-1819) invented the modern steam engine, which became the main source of power in textile mills in Britain during the Industrial Revolution. His engine had a separate condenser through which steam from the cylinder was pased and cooled, allowing the engine to be kept hot. This reduced fuel consumption and saved time. In 1774, together with his busines partner Matthew Boulton (1728-1809), he established a manufactory of steam engines in Soho, near Birmingham. The SI (international standard) unit of power, the watt (W), is named after him.