Leonardo da Vinci designed a water clock using two linked chambers for water.
Leonardo’s hydraulic studies included a clepsydra, or water clock, in which water movement measures elapsed time. In the design, water passes between containers and its changing level provides a time indication. A related version used a float and mechanisms to translate the water’s movement into a visible display or signal.
Water clocks were much older than Leonardo. Ancient Egyptian, Greek, Roman, Chinese, and Islamic engineers developed many forms long before the Renaissance. Leonardo’s importance lies in his detailed mechanical investigations and drawings, not in inventing the basic idea of measuring time with water.
The device should not be confused with a pendulum clock, which depends on a swinging pendulum, or a sandglass, which measures flow through sand. Leonardo also explored water-powered machines, but a water clock uses water primarily as the measuring medium rather than as a source of continuous mechanical power.