It was not so difficult as it sounds. In reality it was quite a simple
plan. The ancients would take a jar, make a tiny hole in the bottom of
it, fill it with water, and let the water drip slowly out. Having
measured how long it would take to empty the jar, they had a sort of
water clock."

"Bravo! That was certainly easy."

"Easy and far better than the sundial, too, for water would drip either
in light or darkness, on cloudy days as well as bright ones. By means of
marks on the jar, shorter intervals of time could also be determined.
The receptacle, however, had to be kept filled and the hole free so
there should be no variation in the regularity of the dripping. This
water clock was called a _clepsydra_, the name being taken from two
Greek words meaning 'thief of water.' Well, as you may imagine, the
populace were delighted with this contrivance. It seemed as if now they
certainly had the prize for which they had been searching. Moreover,
with the water clock a new factor in time came into being. Instead of
telling _when_, as the sundial did, the clepsydra, by measuring a given
interval, told _how long_, which was a very different thing indeed. In
other words it began to draw people's attention to the duration of
time."

"That is different, isn't it?" mused the boy.

"Quite another matter altogether," McPhearson said. "Immediately the
Athenians, who had invented the device, put it to work and proceeded to
limit the length of time speakers should talk in their courts of
justice. Evidently then, as now, men were fond of making speeches and
arguing and became so fascinated by hearing themselves talk that they
forgot to stop. Now here was something that would put a check on them.
When a case came up for a hearing, the accuser was allowed the first jar
of water, the accused the second, and the judge the third. Stationed
beside the clepsydra was a special officer whose duty it was not only to
fill it but to stop the flow whenever a speaker was interrupted, thereby
making certain he was not cheated of any of the time due him."

"A bully scheme!" Christopher remarked.

"It worked," McPhearson answered. "With such strict rules you may be
sure there was none of the thing the Athenians termed 'babbling.' Men
guarded their words like jewels when each word meant the dripping away
of his allotted time."

"And did people continue to use this water clock?"

"Yes, for quite a time, but after a while they began to find fault