Hourglass Since the hourglass was one of the few reliable methods of measuring time at sea, it is speculated that it was used on board ships as far back as the 11th century, when it would have complemented the magnetic compass as an aid to navigation.

Other ancient timekeeping devices include the candle clock, used in China, Japan, England and Iraq the timestick, widely used in India and Tibet, as well as some parts of Europe and the hourglass, which functioned similarly to a water clock.