Leonardo da Vinci sketched a pendulum clock mechanism as an improvement intended to make timekeeping more accurate.
Among Leonardo’s studies of clocks are drawings of escapements, weights, gears, and a pendulum-like regulator. The sketches show him investigating how a regular oscillation could control the movement of a clock. This was centuries before Christiaan Huygens developed the first practical pendulum clock in 1656.
Leonardo did not produce a verified working pendulum clock, and historians debate the exact interpretation of some of his clock drawings. His notebooks contain many alternative mechanisms rather than a single finished design. For that reason, the safest description is a pendulum-clock concept or study, not a completed invention that entered use.
A pendulum clock differs from a water clock, which measures time through controlled water flow, and a sundial, which tracks the Sun’s shadow. Leonardo’s importance here is his investigation of mechanical regulation and precision, not priority for the practical pendulum clock.