As mentioned on the Marine Chronometer page, constructing a clock that functions on board a ship is difficult. Pendulum clocks were the most accurate timekeeping devices in the 1600s and early 1700s, but the rocking of a ship made the pendulum's motion unpredictable and the clock inaccurate.
John Harrison of the UK developed a chronometer that used a spring and balance wheel instead of a pendulum. This won him the Longitude Prize External (worth about £3,000,000 in modern terms) and made ocean-going travel substantially safer.
Harrison's 1761 clock was actually his fourth model. The first three, using different methods for timekeeping, were less successful and less accurate. The beautiful photo above is of the H1 model, which was not sufficient to win the prize.
Sand Glass; Marine Chronometer
- A half-hour video from the Leeds Museum and the BBC entitled The Clock That Changed the World.
- Wikipedia's pages on John Harrison External link, Marine Chronometers External link, and the Longitude Prize.
- The Royal Museums at Greenwich have a description of Harrison's Story
- Harrison's later work, Clock B, is still being tested, as a more recent article from The Guardian attests.