Christiaan Huygens, (1629-95), Dutch astronomer, mathematician, and physicist who developed the wave theory of light and the pendulum clock was born in The Hague.

Huygens made numerous, original scientific discoveries which won him wide recognition and honors among scientists of the 17th century. Among his discoveries was the principle (Huygens Principle) that states that every point on the front of an advancing wave is itself a source of new waves. From this principle he developed the wave theory of light.

In 1655 he found a new method of grinding and polishing lenses. The sharper definitions obtained enabled him to discover a satellite of Saturn and to give the first accurate description of the rings of Saturn. The need for an exact measure of time for observing the heavens led to his applying the pendulum to regulate the movement of clocks (Pendulum clock). In 1656 he devised an eyepiece for the telescope that bears his name.

In Horologium Oscillatorium (1673) he determined the true relation between the length of a pendulum and the period of oscillation and developed theories on centrifugal force in circular motion that assisted the English mathematician Sir Isaac Newton in formulating the laws of gravity. In 1678 he discovered the polarization of light by double refraction in calcite.