clepsydra

Perhaps the earliest mechanical time measure was the clepsydra, or water clock.

Time was measured by the clepsydra, and the expression indicates that the night was far spent and dawn near.

Indeed, the record on one tablet has been interpreted as noting that the astronomer's clock or clepsydra had stopped.

This water clock was called a clepsydra, the name being taken from two Greek words meaning 'thief of water.'

As the sound of the bells died away, the last drop of water fell from the clepsydra and marked the hour of midnight.