ius dates the invention something over 100 years later, attributes it to Ctesibus of Alexandria, who lived under Ptolemy Euergetes, 245 B. C., and who states that water was made to drop upon wheels which turned and actuated a small statue having a stick in his hand.
The figure rotated on its pedestal and pointed to the figures on a numbered circle.
They were, however, known before Ctesibus, but it is probable that he applied toothed wheels to them.
They were introduced into Rome by P. Cornelius Scipio Nasica, 157 B. C. The orators in Rome, in the time of Pompey, were limited to a certain time: as Cicero says, latrare ad clepsydram. It is supposed that among the Romans they consisted of a vessel from which the water issued drop by drop, falling into another vessel in which a rising float indicated against a graduated index the lapse of time.
It may be that they used the hour-glass, a modified form of the clepsydra, sand being substituted for water, and under a gag or five-minute