CLEPSYDRA, the chronometer of the Greeks and Romans, which measured time by the flow of water (Gr. KXE7rretv, to steal, and vhwp, water). In its simplest form it was an earthen ware globe of known capacity, pierced at the bottom with several small holes, through which the water escaped. It was employed to set a limit to speeches in courts of justice, hence the phrases aquam dare (Pliny, Ep. 6. 2. 7), to give the advocate speaking time, and aquam perdere (Quint. II. 3. 52), to waste time.
The clepsydra is said to have been known to the Egyptians. There was one in the Tower of the Winds at Athens ; the turret on the south side of the tower is supposed to have contained the cistern which supplied the water. See classical dictionaries, s.v.
