The British patent number granted to James Watt for his steam-engine improvement in 1769 was 913.
Patent 913 covered Watt’s separate condenser, a device that condensed steam outside the engine’s working cylinder. This prevented the cylinder from being repeatedly cooled and reheated, greatly reducing wasted fuel compared with the Newcomen engine.
Watt’s specification was accepted on January 5, 1769, and enrolled on April 29. Financial backing came first from John Roebuck, and Watt later partnered with Matthew Boulton. Parliament extended the patent’s protection in 1775, allowing it to remain effective until 1800.
A common mix-up is treating 913 as a modern U.S.-style patent number or as the number of Watt’s best-known engine model. It was the number of a specific British patent for the separate condenser; Watt later received several other patents for improvements such as rotary motion and double-acting engines.