Huygens's pendulum clock stayed the most accurate timekeeper for almost 300 years
Christiaan Huygens invented the pendulum clock, found Saturn's moon Titan, explained the planet's rings, and worked out centrifugal force a decade ahead of Newton. His wave theory of light lost out to Newton's particles for over a century, until Augustin Fresnel revived it in 1821.
Huygens was born in The Hague on 14 April 1629, second son of Constantijn Huygens, a diplomat, poet and adviser to the House of Orange who corresponded with Galileo, Mersenne and Descartes. His mother died soon after the birth of his sister. Taught at home until 16, the boy loved building model mills and machines, and studied languages, music, logic and mathematics alongside fencing, dancing and riding.
From 1655 he and his brother Constantijn ground their own lenses for refracting telescopes. With them Huygens discovered Titan and became the first to explain Saturn's odd shape as a thin, flat ring that touches the planet nowhere and tilts relative to the ecliptic. In 1662 he designed a two-lens eyepiece, still called the Huygenian eyepiece, that reduced colour distortion.
Timekeeping made him famous. He patented the pendulum clock in 1657, with Isaac Thuret building examples in Paris, and his 1673 Horologium Oscillatorium, mostly a mathematical study of pendulum motion and curves, ranks among the major 17th-century works on mechanics. He had already found the correct laws of elastic collision by 1656, though they appeared in print only in 1703, and in 1659 he derived the formula for centrifugal force.
His Traite de la Lumiere of 1690 described light as a wave, the first mathematical, mechanical account of something no one could see directly. Newton's rival corpuscular view prevailed until Fresnel extended Huygens's idea to explain diffraction and straight-line travel; physicists now speak of the Huygens-Fresnel principle. In mathematics he developed the theory of evolutes and wrote an early treatise on games of chance, published in Latin in 1657, whose use of expected values later inspired Jacob Bernoulli's probability theory. Historians count him as a central figure of the Scientific Revolution. He died on 8 July 1695.
Source: Christiaan Huygens
