Medieval water clocks were a global marvel of engineering long before they appeared in Europe. | The History Page

In ancient Greece, the need for keeping time accurately led to the invention of the water clock, or clepsydra. These clocks used the flow of water to measure time. But the Greeks didn't stop there—they added a clever twist to protect their treasures. By integrating pebbles into these water clocks, they crafted an alarm system that was both simple and effective. Here's how it worked: a water clock was set up with a mechanism that dropped a pebble onto a metal plate at specific times. This would c