Water Clock

• The Water Clock, also known as a Clepsydra in Ancient Greece, was a device which measured time by the outflow of water from a container.
• In one type, as the water level sank, a vertical floating stick would be read off against a scale. In another type, as vessel or bowl with markings emptied, the time was read off against each mark.

History

• The Water Clock was one of the oldest forms of timekeeping devices, along with the Sundial.
• The earliest records of water clocks date from c. 1500 BCE in Babylon, Egypt, India and China.
• It remained in active use until the invention of the pendulum clock by Galileo in c. 1637 CE.