Willebrord van Roijen Snell

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Willebrord Snell

Willebrord van Roijen Snell (also Willebrordus Snel van Royen or Snellius ; born June 13, 1580 in Leiden , Spanish Netherlands ; † October 30, 1626 ibid) was a Dutch astronomer and mathematician . He is known for the development of the optical law of refraction, named after him as Snell's law of refraction . The invention of triangulation is also attributed to him. He used the name Snellius for scientific publications.

Life

Snell was the son of the scholar and mathematics professor in Leiden Rudolph Snellius (1546–1613), who ran a private school in addition to his professorship, and of Machteld Cornelis's daughter from Oudewater . He studied at Leiden University rights , but was particularly interested in mathematics. He took private mathematics lessons from Ludolph van Ceulen and represented his father, who was not a particularly good mathematician, in his lecture. From 1600 on he moved through several European countries, including to the mathematician and medicine professor Adriaan van Roomen in Würzburg, who introduced him to Tycho Brahe in Prague. He assisted Brahe with astronomical observations and met Johannes Kepler there , who was Brahe's assistant. Brahe died in 1601, however. He also visited Johannes Praetorius in Altdorf and Michael Mästlin in Tübingen , as well as Wilhelm Hatzfeld and Christophorus Vuleius in Hersfeld . In 1602 he returned to Leiden and in 1603 he visited Paris , where he studied law, but also met mathematicians and astronomers. He completed his studies with an M.A. degree in 1608 and married Maria de Langhe in the same year, with whom he had over seven children, three of whom reached adulthood. In Leiden he initially assisted his father and followed him in 1613 as professor of mathematics at the university there. It was a long time before he received full payment from the university, even if he was formally a full professorship from 1615. He died of colic in 1626 . Snell was buried in the Pieterskerk in Leiden, where there is also a memorial of him.

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He was editor, translator and commentator of works by Petrus Ramus , Ludolph von Ceulen and Simon Stevin and of reconstructions of lost works by Apollonios von Perge ( e.g. Apollonius Batavus 1608).

Snellius' triangulation from 1615

In 1615 he developed geodetic triangulation, a new method for land surveying and for determining the circumference and radius of the earth, which he described in his work Eratosthenes Batavus (Dutch Eratosthenes ) published in 1617 . To do this, he used the line from his house to the local church as a baseline and measured the distance from Alkmaar to Bergen-op-Zoom by triangulation , which were roughly on the same longitude. This enabled him to determine the radius of the earth fairly accurately. He dedicated his book to the States General, who gave him a considerable sum for his work.

It is not entirely certain whether he was actually the inventor of the triangulation method. It is often attributed to Gemma Frisius (100 years earlier) or Christoph Bühler .

Snellius also published books with astronomical observations, partly using those of other astronomers such as Brahe or those of Landgrave Wilhelm IV of Hessen-Kassel, for example on the comet of November 1618 in a book from 1619 in which he criticized Aristotle 's views in general . However, he was not a supporter of the Copernican system , but, like Ramus and Brahe, saw the earth as the center of the universe.

He also improved Archimedes' method of exhaustion for calculating the number π in his book Cyclometricus, de circuli dimensione of 1621. He gave the correct value to seven places.

He found the law of refraction named after him, which had already been found several times before, in 1621. It was not published by him, but Christian Huygens first uncovered his contribution in his Dioptrik published in 1703. A Snell manuscript on optics is in the library of the University of Amsterdam. It shows that he knew the literature on optics well. The law of refraction was published by René Descartes in his Dioptrique 1637 (who does not give any sources). It was also known to Thomas Harriot (around 1601) and Abu Sad al-Ala ibn Sahl (984).

A year after his death, his book on trigonometry (Doctrina triangulorum) was published.

In his Tiphys batavus , published in 1624, he dealt with navigation and treated the loxodromes . He also dealt with the problem of meridian division and the resulting consequences for navigation. Snell published a solution to Pothenot's problem, the plane backward cut problem .

The Royal Netherlands Navy has named a hydrographic survey vessel, the Snellius , after him. In addition, the lunar crater Snellius and the lunar valley Vallis Snellius are named after him.

Works

Cyclometricus , 1621

literature

Web links

Commons : Willebrord Snellius  - Collection of images, videos and audio files

Individual evidence

  1. ^ Friedrich Seck: History of science around Wilhelm Schickard , section on Gemma Frisius and Christoph Bühler's triangulation
  2. ↑ Coeli et siderum in eo errantium observationes Hassiacae (1618)
  3. ↑ Descriptio cometae, qui anno 1618 mense Novembri primum effulsit , original from the Herzog August Library Wolfenbüttel ( Memento of the original from December 22, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , Elzevir publishing house, Leiden 1619 @1@ 2Template: Webachiv / IABot / sunny.biblio.etc.tu-bs.de
  4. ^ Œuvres complètes de Christiaan Huygens . T. 13: Dioptrique, Fasc. 1. 1653; 1666, p. 6.
personal data
SURNAME Snel, Willebrord van Roijen
ALTERNATIVE NAMES Snell van Royen, Willebrord; Snellius, Willebrord
BRIEF DESCRIPTION Dutch astronomer and mathematician
DATE OF BIRTH June 13, 1580
PLACE OF BIRTH Suffer
DATE OF DEATH October 30, 1626
Place of death Suffer