He was led to this invention by his experiments with light and colors.
In 1671 he presented to the Royal Society a second and somewhat larger telescope, which he had made; and this type of instrument was little improved upon until the introduction of the achromatic telescope, invented by Chester Moor Hall in 1733.
As is generally known, the element of accurate measurements of time plays an important part in the measurements of the movements of the heavenly bodies.

In fact, one was scarcely possible without the other, and as it happened it was the same man, Huygens, who perfected Kepler's telescope and invented the pendulum clock.

The general idea had been suggested by Galileo; or, better perhaps, the equal time occupied by the successive oscillations of the pendulum had been noted by him.

He had not been able, however, to put this discovery to practical account.

But in 1656 Huygens invented the necessary machinery for maintaining the motion of the pendulum and perfected several accurate clocks.