To follow the further development of the water-clock we must pass from China to Greece. In their early history the Greeks had nothing better than the sun-dial with which to measure time. About the middle of the fifth century B. C. there arose at Athens a need for a better timepiece. In the public assembly the orators were consuming too much time, and in the courts of law the speeches of the lawyers were too long. It was a common thing for a lawyer to harangue his audience for seven or eight hours. To save the city from being talked to death a time-check of some kind became necessary. The sun-dial would not answer, for the sun did not always shine, even in sunny Greece; so the idea of the water-clock was borrowed. A certain amount of water was placed in an amphora (urn), in the bottom of which was a small hole through which the water might slowly flow (Fig. 5). When the amphora was empty the speaker had to stop talking. The Greeks called the water-clock a _clepsydra_, which means "the water steals away." The orator whose time was limited by a certain amount of water would keep his eye on the clepsydra, just as a speaker in our time keeps his eye on the clock, and if he were interrupted he would shout to the attendant, "You there, stop the water," or would say to the one who interrupted him, "Remember, sir, you are in my water." The story goes that upon one occasion the speaker stopped every now and then to take a drink; the orator's speech, it seems, was as dry as his throat, and a bystander cried out: "Drink out of the clepsydra, and then you will give pleasure both to yourself and to your audience." [Illustration: FIG. 6.--AN IMPROVED GREEK CLEPSYDRA.] At first the Greeks used a simple form of the clepsydra, but they gradually adopted the improvements made by the Chinese, and finally added others. The great Plato is said to have turned his attention to commonplace things long enough to invent a clepsydra that would announce the hour by playing the flute. However this may have been, there was in use in the Greek world, about 300 B. C., a clepsydra something like the one shown in Fig. 6. This begins to look something like a clock. As the water drops into the cylinder _E_ the float _F_ rises and turns _G_, which carries the hour hand around. Inside of the funnel _A_ is a cone _B_ which can be raised or lowered by the bar _D_. In this way the dropping of the water is regulated. Water runs to the funnel through _H_, and when the funnel is full the superfluous water runs off through the pipe _I_, and thus the depth of the water in the funnel remains the same and the pressure does not change. Notice that when the hand in this old clock has indicated twelve hours it begins to count over again, just as it does on our clocks to-day. How easily it would have been to have continued the numbers on to twenty-four, as they do in Italy, and on the railroads in parts of Canada, to-day.