Who invented the pendulum clock?

Solution

Galileo Galilei discovered the isochronism of the pendulum in 1583. This was the turning point from the age of mechanical clocks not controlled by periodic motion to the age of mechanical clocks moved by continuous oscillation in a fixed cycle. Galileo conceived of an isochronous pendulum clock in 1637, but never went on to complete it. In 1656, fourteen years after Galileo’s death, Christiaan Huygens used a pendulum for a weight-driven clock with a crown wheel escapement, thereby inventing the first pendulum clock.