Water clock (clepsydra)
device · 1500 BC · Ancient world
Measuring time by the outflow of water.
What it is made of
- Vessel with an outflow hole — has part. Water flows out at a nearly constant rate.
- Water level markings — has part. Hour marks on the wall.
Principles and materials it uses
- Gravity flow — uses. Water flows out at a constant rate under gravity.
- Stone — is made of. The clepsydra from Karnak is a stone vessel.
History: what it evolved from and what it influenced
- Mechanical clock — evolved into. Mechanical clocks replaced water clocks, swapping the flow of water for an escapement.
Things built in a similar way
- Sundial — works like. Two ancient ways to measure time: by a shadow and by flowing water.
- Hourglass — works like. The same principle of timing by outflow, with sand instead of water.