HUYGENS, hoi-gas or Mar, Chris tian, Dutch mathematician, astronomer and physicist : b. The Hague, 1629; d. there, 8 June 1695. He studied at Leyden, and at Breda, where he went through a course of civil law from 1646-48. He settled in Paris at the in vitation of the minister, Solbert, was elected to the Academy and was given rooms at the Royal Library. He returned to Holland when the Edict of Nantes was revoked, and remained there till his death. Among his most important contributions to science are his investigations on gravitational acceleration and the oscillations of the pendulum, which he was the first to apply to clocks, and his 'System of Saturn,' in which he first proved that the ring completely sur rounds the planet, discovered the fourth satel lite, and determined the inclination of its plane to that of the ecliptic. He perfected the tele scope and invented the micrometer. In 1690 he published important treatises on light and on weight. His 'Traits de la lumiere> was an exposition of the undulation theory, but in con sequence of the prevalence of the Newtonian theory was long neglected till later researches established its credit. Huygens discovered the
polarization of light, which he could not ex plain because he thought the vibrations of light longitudinal rather than transverse. He also investigated the theory of probabilities. Huy gens also wrote 'Theoremata de Quadratura Hyperbolis, Ellipsis, et Circuli, ex Date Por tionum Gravitatis Centro) '(1651); Circuli Magnitudine Invents' (Leyden 1654) ; Ratiocinatione in Ludo Alm' (1656); 'Hor logium Oscillatorium, sive de Motu Pendu lorum) (1673). His works have been published in 10 volumes by the Koninglijke Akademie van den Wetenskapen (The 'Hague 1888-1905). Consult Bosscha, 'Christian Huygens) (tr. into German, Leipzig 1895); Harting, P., 'Christian Huygens in Zijn Leven en Werken Geschetzt' (Groningen 1868).