What are clepsydras?

A clepsydra is like a clock that uses water instead of numbers or hands to show how much time has passed.

Imagine you have a big container full of water, and it slowly drips into another empty one below it. As the water moves from one to the other, you know time is passing, just like when your favorite toy slowly loses its batteries as it runs out of power.

A clepsydra has two parts: a top container that holds water and a bottom one that catches it. Water trickles through a small hole from the top to the bottom. The more water that moves, the more time that goes by. People used these clever clepsydras in ancient times to measure how long speeches lasted or to keep track of games, just like a timer on your phone does today.

Think about when you pour water from one glass to another. If you do it slowly, you can watch the water level go down and up. That’s exactly what happens in a clepsydra, only instead of watching glasses, people watched the flow of water to know how much time had passed.