Gregory, James; Gregory, David; Huygens, Christiaan

The Dutch mathematician, astronomer and physicist Christiaan Huygens was born in The Hague on 14 April 1629. His father was the diplomat, Latinist and poet Constantijn Hugens (1596-1687), friend and correspondent of Descartes (1596-1650) and many other intellectuals of the time. Showing an early talent for mechanics, drawing and mathematics, Huygens entered the University of Leiden in 1645 studying mathematics and law. In 1647 he was studying in Breda, and in 1655 came a first visit to Paris. By then, he had established a European reputation through his scientific publications, and just before a second visit to Paris in 1660 where he met Blaise Pascal (1623-1662), he discovered the true shape of the rings of Saturn. This discovery in 1659 built on his earlier discovery of a satellite of Saturn in 1655 and the stellar components of the Orion nebula in 1656. Huygens also discovered the pendulum as a regulator of clocks, describing this in Horologium (1658). From 1666 to 1681, he lived in Paris, and in 1666 he was one of the founding members of the French Academy of Sciences. In France, he made the acquaintance of German mathematician and philosopher Gottfried Wilhelm Leibnitz (1646-1716). Illness prompted him to return to the Netherlands in 1681 and the subsequent revocation in 1685 of the Edict of Nantes (which had allowed Protestants certain liberties in France) prevented him from ever returning to Paris. In 1689, Huygens visited London, meeting Sir Isaac Newton (1643-1727) and lecturing on his own theory of gravitation. Although his theory of gravitation was never taken seriously, his work on rotating bodies and his contributions to the theory of light have been of lasting importance. Other publications include De circuli magnitudine inventa (1654), Horologium oscillatorium (1673), Discourse on the cause of gravity (1690), and Treatise on light (1690). Christiaan Huygens died in The Hague on 8 July 1695.