Leonardo da Vinci designed a water clock that measured time through the movement of water between containers.
Water clocks, also called clepsydras, had existed long before Leonardo, but he studied ways to improve their precision and display. In his designs, water could fill or empty a vessel, move a float, and indicate elapsed time on a scale.
The mechanism reflects Leonardo’s interest in converting continuous natural processes into measurable motion. Because water flow can vary with pressure, temperature, and vessel shape, careful construction was necessary for reliable readings.
Leonardo’s water-clock work should not be confused with his later interest in mechanical escapements. A water clock uses liquid flow, while a pendulum clock depends on a swinging pendulum and was developed after Leonardo’s lifetime.