Clever Origins
People around the world were already making valiant attempts to predict solstices and other astronomical occurrences back in the Neolithic era.
Water clocks, along with sundials, are most likely the oldest time-measuring instruments, with the only exceptions being the tally stick, which counts days. Given their extraordinary antiquity, where and when these time pieces first existed is not known — and perhaps will remain unknowable.
The bowl-shaped outflow water clock, or clepsydra (“water thief”) is the simplest form of such clocks; they are known to have existed in Babylon and in Egypt around the 16th century BC.
The ancient Greeks—of course—were among the first to create mechanical clocks to measure time; the perfection of the clepsydra and the alarm clock created by Plato are just two such brilliant inventions.
Plato, the famous ancient Greek philosopher and mathematician who lived from ca. 427 BC to 347 BC, and who founded the first institution of higher education in the Western world, the Academy of Athens, was said to have been the first person to introduce the snooze alarm into human history.
In his effort to wake people up and get them to their lectures on time — at dawn — Plato designed a mechanism which can be considered the first alarm clock.
In his mechanism, water would drip from one vessel into another via a small hole, and as the second vessel filled during the night, trapped air was forced out of a side vent, making it whistle like a tea kettle when it filled up quickly.
The Water Clock at the Amphiaereon of Oropos
Located at the Amphiareion of Oropos, a sacred site which contains the ruins of a theater, altars, a sacred spring and many other historical artifacts of immense value, this water clock — roughly contemporary with Plato’s alarm clock — is one of the most outstanding for the level of scientific expertise it represents.
The site of a holy spring where tales of heroes blended into myth, it is said that the earth once opened up and swallowed a chariot owned by Amphiaraos in that very spot. It became a site of worship and the place where athletic games took place once every five years.
On the southeast side of the streambed opposite the sacred spring there is the wonderfully well-preserved clepsydra, which incredibly still has its bronze stopper. This artifact is especially important in the study of ancient methods of timekeeping in that it is an example of an inflow water clock.
Since an inflow clock measures time by the filling of a known volume from a constant rate of inflow, it is much more accurate than an outflow water clock in measuring the gradations between full and empty.
The clepsydra at Oropos was composed of a central, square reservoir with a stairway on the south side to allow access to the bronze plug at the bottom of the reservoir, all of which are still extant.
Ctesibius’ water clock
Ctesibius — who is known today as the father of pneumatics, or the physics of air pressure, and who is credited with the invention of the hydraulic organ, improved on the water clock so much that his version was the most accurate clock constructed for the next 2,000 years until the Dutch physicist the invention of the pendulum clock in 1656.
“Now what Ctesibius did was particularly cunning,” explains Marty Jopson, a model maker who created a new version of the clock invented by Ctesibius, noting that he made sure that the height of water in the initial chamber never changes.
He accomplished this by feeding water into one chamber and attaching an overflow pipe which fed into another chamber. The water in that second chamber would rise at a precise rate, allowing time to be measured accurately. This was nothing less than a stroke of genius. But in order to have a water clock that would operate continually, without a chamber having to be emptied, something had to be altered.
“What he did was that he added a siphon to the system,” Jopson notes, adding “this may well be the very first time a siphon was fitted to a machine.” Ctesibius is therefore known as the creator of the siphon. This allowed the clock to be emptied and refilled automatically, which was nothing short of revolutionary.
But how the Greeks measured time itself posed a problem. They divided the daylight hours into twelve — so that the hours were shorter in the winter than in the summer. That led to the need to create a clock on which they could rely for accurate timekeeping.
So Ctesibius created a waterwheel and a series of cogs that turned a cylinder which turned a tiny amount every day, tracing the hour lines on a pole, which would be nearer or father apart depending on the time of the year. This itself is a marvel of human engineering.
“Ctesibius’ water clock ran seven days a week, 365 days a year. For over two thousand years, this was the most accurate clock in the world,” Jopson says.