Clocks

[Susmith]

When were clocks first used?

[incitatus]

Sundials and water clocks were both used by the egyptians about 4-6000 years ago. There may have been earlier ones in sumeria, but I dont think we have direct evidence for these.

[ursula]

The Egyptians first measured time during the day using shadow clocks - similar to sun dials. It seems that the first shadow clocks were based on the shadow from a bar crossing marks which represented hourly periods. At midday, the shadow clock would be reversed and hours counted down to dusk. Next the Egyptians invented the water clock or 'clepsydra'. It worked by allowing water to drip through a small hole from one container to a lower one. Marks on one container indicated how many hours had passed. Some Egyptian clepsydras had different sets of marks for different seasons.