John Harrison

Solved the longitude problem with the marine chronometer, revolutionizing global navigation

John Harrison, an 18th-century English clockmaker, transformed maritime exploration by inventing the first precise marine chronometer. Before his innovation, sailors struggled to determine longitude at sea, leading to catastrophic navigation errors. Harrison’s H4 chronometer, completed in 1761, could maintain accurate timekeeping even in harsh oceanic conditions, enabling sailors to calculate longitude using celestial navigation.

Harrison’s decades-long battle for recognition from the British Board of Longitude is a tale of perseverance. Despite political resistance, his chronometer eventually became indispensable. By the 19th century, his invention was standard on ships, reducing risks of shipwrecks and enabling safer global trade. Learn more about his legacy at the Royal Museums Greenwich.