Centuries-Old Longitude Clock Runs Again

douglips writes "BBC News has published a story about John Harrison's H4 chronometer and how it has been wound up for the UK's National Science Week. After 40 years of work [Harrison] proved in 1764 that a clock could be used to locate a ship's position at sea with extraordinary accuracy." Ah, the GPS system of its day. T. adds: This is the timekeeping device which Dava Sobel wrote about in Longitude .