Mathematician:Christiaan Huygens

Mathematician
Dutch mathematician, astronomer, physicist and horologist.

Studied the rings of Saturn and discovered its moon Titan.

Invented the pendulum clock.

Believed that light travels in waves, hence the Huygens-Fresnel Principle. Developed in improved method of grinding lenses for telescopes.

Noticed a surface feature of Mars, and from there determined the length of a Martian day.

Introduced the concept of expectation.

Established the laws of impact for elastic bodies, refuting the erroneous work of in his $1644$ work Principia Philosophiae.

Made the first detailed study of the evolute and involute of a curve in the plane.

Served as a mentor to young.

Investigated protozoology in order to repeat the work of Antonie Philips van Leeuwenhoek, and left extensive manuscripts which, had they been published, may well have brought the science of microbiology forward by two centuries. For one thing, he anticipated the work of Louis Pasteur.

Deduced the laws of reflection and refraction, and explained the reason behind the double refraction of Iceland Spar.

Estimated the distance of the star Sirius as being $27 \, 664$ times as far away from Earth as the sun. This was inaccurate, but no better estimate was forthcoming for another century.

Nationality
Dutch

History

 * Born: 14 April 1629 in The Hague, Netherlands
 * 1663: Elected Fellow of Royal Society of London
 * 1666: Moved to Paris at the urging of Jean-Baptiste Colbert
 * 1669: Presented to the Royal Society a correct statement on the laws of impact of elastic bodies
 * 1681: Returned to The Hague, as Paris was becoming intolerant of Protestants
 * Died: 8 July 1695 in The Hague, Netherlands

Theorems and Definitions

 * Huygens-Fresnel Principle (with )
 * Parallel Axes Theorem (also known as the Huygens-Steiner Theorem, with )

Books and Papers

 * 1649: De iis quae liquido supernatant (About the parts above the water) (unpublished)
 * 1651: Cyclometriae
 * 1651: Theoremata de quadratura hyperboles, ellipsis et circuli (theorems concerning the quadrature of the hyperbola, ellipse and circle)
 * 1654: De circuli magnitudine inventa
 * 1656: De Saturni Luna observatio nova (About the new observation of the moon of Saturn)
 * 1656: De motu corporum ex percussione (published in 1703)
 * 1657: (translated by  as Van reeckening in spelen van geluck)
 * 1659: Systema saturnium (on the planet Saturn)
 * 1673: (theory and design of the pendulum clock)
 * 1673: De vi centrifuga (Concerning the centrifugal force)
 * 1684: Astroscopia Compendiaria tubi optici molimine liberata (compound telescopes without a tube)
 * 1685: Memoriën aengaende het slijpen van glasen tot verrekijckers (How to grind telescope lenses)
 * 1686: Kort onderwijs aengaende het gebruijck der horologiën tot het vinden der lenghten van Oost en West (How to use clocks to establish the longitude)
 * 1690: Traité de la lumière (Treatise on [the nature of] light)
 * 1690: Discours de la cause de la pesanteur (Discourse about gravity, possibly written in or around 1669)
 * 1691: Lettre touchant le cycle harmonique (concerning the 31-tone system)

Posthumous Publications

 * 1698: Cosmotheoros (solar system, cosmology, life in the universe)
 * 1703: Opuscula posthuma, including:
 * De motu corporum ex percussione (Concerning the motions of colliding bodies: contains the first correct laws for collision, dating from 1656).
 * Descriptio automati planetarii (description and design of a planetarium)
 * Dioptrica (in which the Snell-Descartes Law appears)
 * 1724: Novus cyclus harmonicus
 * 1728: Christiani Hugenii Zuilichemii, dum viveret Zelhemii toparchae, opuscula posthuma ... or: Opera reliqua (about optics and physics)

Notable Quotes

 * The world is my country, and science is my religion.