Water Clock

ancient technology · time measurement · clever engineering

What it does. A water clock measures time by letting water drip at a steady, controlled rate from one container into another. As the water collects, markings on the container show how much time has passed.

Very ancient invention. Water clocks are one of humanity's oldest timekeeping devices, used by ancient Egyptians, Greeks, and Chinese civilizations thousands of years ago. They were especially useful before mechanical clocks were invented.

Steady and reliable. The genius of a water clock is that liquid always flows at roughly the same speed (gravity pulls it down at the same rate), so you can trust it to measure time accurately without needing any moving parts.

Two directions work. Water clocks can measure time by water flowing out of a vessel (emptying) or by water flowing into a vessel (filling up). Both methods work equally well for tracking hours passing by.

Better than the sun. Unlike sundials that only work in daylight, water clocks worked anytime, day or night, making them invaluable for priests, sailors, and anyone who needed to know the time at night.