HUYGENS, hi'grmz, Dutch pram, hoiWns, CHRISTIAN 1629-95). 21 celebrated Dutch mathe matician, physicist, and astronomer. Ile was born at The Hague. the second son of Constan tijn Huygens van Zuyliehem. a poet and see•e tary and counselor to the Princes of Orange. Ile studied at Leyden and Breda, devoting himself at first to law, and then pursuing the study of mathematies. At the invitation of Minister Solbert of France, he settled in l'aris, being given rooms in the Royal Library and made a member of the Academy. After the revocation of the Edict of Nantes he returned to Holland, where he lived the rest of his life. Ibis early work, Theoremetta de Quadra/aro Ilyperbolis, ct Cirenli, r,E Dato Po•tionum ara•itatis Centro (1651), is an example of the talent which In at the foundation of all his scientific. achieve ments. This was followed by his Dr Circuit: Magnitudine Inrenta (Leyden, 1654). reprinted in Rudio. t rehintreles, Huygens, Lambert, Er Yenotre (Leipzig, IS921, the object of each work to expose the fallacies of Gregoire do Saint Vitn.ent. He also \roil:A on the doctrine of prob abilities already founded by Pascal and Fermat and published Dr lhrtian tic:!(Me iu Ludo .1/co; (1656). Hitygens was the first to apply the pen dulum to cloeks and to use the device to deter mine the acceleration of gravity. A eomplete description of Iluygens's apparatus is contained in his great work, llorologium Oscillatorium, sire de Motu l'enelutorum (1673). Ile also de velmted and gave provision to the investigations of Galileo upon accelerated motion under the action of gravity; and there is no doubt that to his studies and discoveries his great successor, Newton, in preparing, his magnificent develop ment of the principle of accelerating force, was largely indebted. Newton was a student and nil mirer of his works, and assigns to him, along with Sir Christopher Wren and Wallis, the distin guished epithet of hajus alatis gromctra•unt facile principes.
Huygens was the first to construct powerful telescopes, and in 1655 discovered the ring of Saturn and the fourth satellite of that planet. In 1659 he published an aeconnt of these dis eoveries in a work entitled Systema Ratu•niuM. In the end of this work is described an invention of great importance in astronomy; namely, the In icromelor GI. V. , by which small angles between objects viewed by a telescope are accurately masured.
In 1660 Huygens visited England, where he was admitted a member of the loyal Society. Huygens was the originator of the wave theory of light; and this theory, now accepted, was first stated by him in in his Traite de in br ittle-re (first printed in 1690; modern German translation in Ostscald's Flassiker No. 20, Leip zig). In this theory light is conceived to he a form of motion in the medium through which it passes. (See LIGHT.) Later (1690) he was able to explain both reflection and refraction by wave motion in the ether, and \VII, 111,41 a bh• 0) aroma for double refraction. To lluygens is due the dis covery of polarization, a phenomenon which eould not then be explained by the undulatory theory, and led Newtiat to adopt the emission theory. Huygens was in error, however, ill belie% ing that the vibrations were longitudinal rather than transverse. The undulatory theory, however, did not gain general acceptance until the nineteenth century, when the experiments of Young and Fresnel placed it on a firm basis.
A new edition of Iluygens's collected works has been published by the Holland Academy ,of Sciences in six volumes (The lla.ote. 1888-95). For his biography, consult, uygens, I:erman translation by Engelmann (Leipzig, 1895).