Q1684Ships could not work out how far east or west they were, and thousands died for it. A self-taught carpenter named John Harrison spent forty years building a clock accurate enough at sea to solve it — against astronomers who insisted the answer lay in the stars.
Latitude was easy; longitude required knowing the exact time at a reference port, and no pendulum clock could keep time on a rolling, damp, temperature-swinging ship. Harrison, a Lincolnshire carpenter with no formal training, built a series of increasingly refined machines, ending with a watch about the size of a large pocket watch that lost only a few seconds on a voyage to Jamaica. The Board of Longitude, dominated by astronomers backing a rival method, withheld the prize for decades. He was eventually paid after appealing to the king.












