A Chronology of Clocks

Category: Resources | Timeline

  • 3500 BC: Ancient Egyptians build obelisks (giant sundials) to track the sun.
  • 1500 BC: First water clocks (clepsydras) developed in Egypt and Babylon.
  • 200 BC: Greeks develop the Antikythera Mechanism, the first known analog computer.
  • 725 AD: Yi Xing in China develops the first mechanical escapement for a water clock.
  • 1283 AD: The oldest surviving mechanical clock is installed at Salisbury Cathedral.
  • 1656 AD: Christiaan Huygens invents the pendulum clock, dramatically increasing accuracy.
  • 1761 AD: John Harrison completes the H4 Marine Chronometer, solving the longitude problem.
  • 1884 AD: The International Meridian Conference establishes Greenwich as the Prime Meridian.
  • 1927 AD: Warren Marrison builds the first quartz clock.
  • 1949 AD: The first atomic clock (using ammonia) is built at the U.S. National Bureau of Standards.
  • 1970 AD: The Unix Epoch begins.
  • 1972 AD: Leap seconds are introduced to keep atomic and solar time in sync.