The clepsydra of Ctesibius

Tosibius came up with a brilliant answer and he changed the history of timekeeping forever. He took clocks from a couple of buckets to this. Something intricate, remarkable and completely groundbreaking. The first ever accurate and fully automatic clock. Now what Tosibius did is particularly cunning. He makes sure that the height of water in this chamber never changes. Tosibius did this by continually feeding water to the top and attaching an overflow pipe. The water then flowed into a second chamber which would rise at a steady and precise rate, allowing time to be measured accurately. This was genius. But Tosibius still wasn't happy. The second chamber had to be emptied when full and he wanted a clock that would run and run. Surely this was impossible. What he did was he fitted a siphon to the system and this may well be the first time a siphon was ever fitted to a machine. With a siphon, the clock emptied and reset itself automatically. This was revolutionary. The world had never seen a machine like this before. But there was still one remaining problem. The Greeks divided the daylight hours into 12. So their hours were shorter in winter than in summer. Even our modern clocks would struggle with that. Using a water wheel and a series of cogs, a cylinder turned a tiny amount every day, the hour lines becoming nearer or farther apart depending on the time of the year. The precision involved is simply astonishing. So overall, Tosibius' water clock ran 24 hours a day, seven days a week, 365 days a year. And for over 2,000 years, this was the most accurate clock in the world.