Leonardo da Vinci studied an escapement with two connected weights to make a timekeeper more accurate.
An escapement is the mechanism in a clock that releases stored energy in controlled steps. It lets the gear train advance incrementally while receiving regular impulses from the regulating element. Leonardo’s notebooks include a design using two alternating weights, a concept sometimes called a gravity escapement.
The alternating action was intended to control the motion of the clock’s gears more evenly than a continuously running train. Leonardo was deeply interested in mechanical timekeeping and drew gears, springs, and other components in several notebooks. His studies were exploratory and did not produce a documented working clock of this exact type.
This mechanism should not be confused with the pendulum itself. Galileo studied the pendulum’s timekeeping properties, and Christiaan Huygens patented the first pendulum clock in 1656. Leonardo’s escapement studies predated those developments, but they did not create the pendulum clock. They show his interest in regulating motion through repeated, precisely timed mechanical release.