Christiaan Huygens. Engraving of Christiaan Huygens (1629-95), Dutch inventor of the pendulum clock, presenting one of his timepieces to King Louis XIV (1638-1715) of France in 1659. The idea of using a pendulum to measure time had been prop- osed by Galileo (1564-1642) but he had not found how to keep one swinging. On Christmas Day 1656 Huygens designed a table clock that kept the pendulum swinging by means of a spring. He later made further advances in time-keeping. Huygens moved to France to work for Louis XIV during 1666- 81 and published the results of his clock research in Horologium Oscillatorium (1673). Huygens also made advances in optics, astronomy & mathematics.