Mathematician:Willebrord van Royen Snell

Full name in the original Dutch: Willebrord Snel van Royen, or Willebrord van Royen Snell, also Willebrord Snellius.

Dutch applied mathematician and astronomer who founded the modern science of geodesy, by pioneering the technique of triangulation.

Developed an improved method for determining the value of $\pi$ (pi) using polygons.

Discovered the Sine Law.

Known today for rediscovering Snell's Law in 1621, governing the refraction of light. He did not publish himself. It first appeared in 1703 when it was published in Huygens' Dioptrica. Note: Several source works (notably the 1911 Encyclopedia Britannica) give his birth year as 1591. It is apparent that this is an error.

Nationality
Dutch

History

 * Born: 13 June 1580, Leiden, South Holland, Union of Utrecht (what is now known in English as the Netherlands).
 * From 1600: Travelled to various European countries, mostly discussing astronomy.
 * 1602: Went to Paris to continue studies
 * 1604: Visited Switzerland with his father
 * 1607: Received degree from Leiden
 * 1613: Succeeded his father as professor of mathematics in the university of Leiden
 * 1615: Planned and executed a new method of finding the dimensions of the earth, by triangulation
 * Died: 30 Oct 1626, Leiden

Theorems

 * Snell's Law

Books and Papers

 * 1617: Eratosthenes Batavus (the Dutch Eratosthenes)
 * 1618: Coeli et siderum in eo errantium observationes Hassiacae by William IV of Hesse (edited)
 * 1621: Cyclometria sive de circuli dimensione
 * 1624: Tiphys Batavus
 * 1627: Doctrina triangulorum (posthumous)

Also see

 * : $$\S 6$$: Footnote