1-153-112 - Ann Ronan Picture Library/Heritage-Images

Christiaan Huygens (1629-1695), Dutch physicist, mathematician and astronomer, c1870. Huygens made important contributions in several scientific fields. He postulated that light consisted of waves, determined the nature of Saturn's rings, developed the pendulum clock, and applied the balance spring to the pocket watch. He also wrote the first book on Probability Theory, published in 1657.