Willebrord Snellius
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Willebrord Snellius | |
|---|---|
 Willebrord Snel van Royen (1580–1626) | |
| Born | 13 June 1580 |
| Died | 30 October 1626 (aged 46) |
| Nationality | Dutch |
| Alma mater | University of Leiden |
| Known for | Snell's law, Snellius's triangulation, Snellius–Pothenot problem |
| Scientific career | |
| Fields | Astronomy and mathematics |
| Institutions | University of Leiden |
| Academic advisors | Ludolph van Ceulen Rudolph Snellius |
| Notable students | Jacobus Golius |
Willebrord Snellius[1][2] (born Willebrord Snel van Royen[3] (13 June 1580[4] – 30 October 1626), commonly known simply as Snellius and Snell, was a Dutch astronomer and mathematician.
Snell is best known for the law of refraction of light known as Snell's law,[5] his pioneering work in survey known as Snellius's triangulation, and the Snellius–Pothenot problem, a means in planar trigonometry of finding an unknown point from known ones.
Early life
[edit]Willebrord Snellius was born in Leiden, Netherlands. In 1613 he succeeded his father, Rudolph Snel van Royen (1546–1613) as professor of mathematics at the University of Leiden.[6]
Surveying
[edit]
In 1615, Snellius, became the first known surveyor since Eratosthenes in 3rd century BC Ptolemaic Egypt to use triangulation to make a large-scale arc measurement to determine the Earth's circumference.[7][8]
In his work The terrae Ambitus vera quantitate (1617) under the author's name ("The Dutch Eratosthenes") Snellius describes achieving his result by calculating the distances between a number of high points in the plain west and southwest of the Netherlands using triangulation. By necessity Snellius's high points were nearly all church spires, virtually the only tall buildings at that time in the west of the Netherlands. More or less ordered from north to south and/or in successive order of measuring, Snellius used a network of fourteen measure points to make a total of 53 triangulation measurements.
These cities were: Alkmaar: St. Laurenskerk; Haarlem: Sint-Bavokerk; Leiden: a then new part (built in 1599) of the city walls;[9] The Hague: Sint-Jacobskerk; Amsterdam: Oude Kerk; Utrecht: Cathedral of Utrecht; Zaltbommel: Sint-Maartenskerk; Gouda: Sint Janskerk; Oudewater: Sint-Michaelskerk; Rotterdam: Sint-Laurenskerk; Dordrecht: Grote Kerk; Willemstad: Koepelkerk; Bergen-op-Zoom: Gertrudiskerk; Breda: Grote Kerk.
Snellius was helped in measuring by two of his students, the Austrian barons Erasmus and Casparus Sterrenberg. In several cities he also received support of friends among the civic leaders (regenten).[citation needed]
In order to carry out these measurements accurately Snellius had a large quadrant built, with which he could accurately measure angles in tenths of degrees. This instrument can still be seen in the Museum Boerhaave in Leiden. In his calculations Snellius made use of a solution for what is now called the Snellius–Pothenot problem.
He came up with an estimate of 28,500 Rhineland rods – in modern units 107.37 km[10] for one degree of latitude. 360 times 107.37 then gives a circumference of the Earth of 38,653 km. The actual circumference is 40,075 kilometers, making Snellius' estimate 3.5% low.
Mathematics and physics
[edit]Snellius was also a distinguished mathematician, producing a new method for calculating π—the first such improvement since ancient times. He discovered the law of refraction in 1621.[11]
Other works
[edit]
In addition to the Eratosthenes Batavus, he published Cyclometricus, de circuli dimensione (1621), and Tiphys Batavus (1624). He also edited Coeli et siderum in eo errantium observationes Hassiacae (1618), containing the astronomical observations of Landgrave William IV of Hesse. A work on trigonometry (Doctrina triangulorum) authored by Snellius was published a year after his death.[6]
Death
[edit]
Snellius died in Leiden in October 1626, at the age of 46 from an illness diagnosed as colic.[12] His grave can be seen in the Pieterskerk, Leiden.
Legacy
[edit]Snellius Glacier in Antarctica is named after Willebrord Snellius.
The lunar crater Snellius is named after Willebrord Snellius.
The Royal Netherlands Navy has named three survey ships after Snellius, including a currently-serving vessel.
Works
[edit]- Eratosthenes Batavus (in Latin). Lugduni Batavorum: Joost van Colster, Joris Abrahamsz van der Marsce. 1617.
- Coeli et siderum in eo errantium observationes Hassicae (in Latin). Lugduni Batauorum: Joost van Colster. 1618.
- Cyclometricus (in Latin). Lugduni Batavorum: Matthijs Elzevier, Bonaventura Elzevier. 1621.
- Doctrinae triangulorum canonicae libri quatuor (in Latin). Lugduni Batavorum: Joannes Maire. 1627.
See also
[edit]- Area of a circle – Concept in geometry
Notes
[edit]- ^ Willebrord Snellius at the Leiden Digital Family Tree.
- ^ Eerste Nederlandse Systematisch Ingerichte Encyclopaedie
- ^ Encarta Winkler Prins, Grote Oosthoek, Eerste Nederlandse Systematisch Ingerichte Encyclopaedie
- ^ Sometimes mistakenly noted as 1590 or 1591; Cf. P.C. Molhuysen; P.J. Blok, eds. (1927). "Snellius, Willebrord". Nieuw Nederlandsch biografisch woordenboek. Leiden..
- ^ For a reconstruction of this discovery see Hentschel 2001. It is now known that this law was already known to Ibn Sahl in 984. The same law was also investigated by Ptolemy and in the Middle Ages by Witelo, but due to lack of adequate mathematical instruments (i.e. trigonometric functions) their results were saved as tables, not functions.
- ^ a b Chisholm 1911.
- ^ Haasbroek, N.D. (1968): Gemma Frisius, Tycho Brahe and Snellius and their triangulation. Publ. Netherl. Geod. Comm., Delft. [1]
- ^ Torge, W.; Müller, J. (2012). Geodesy. De Gruyter Textbook. De Gruyter. p. 5. ISBN 978-3-11-025000-8. Retrieved 2 May 2021.
- ^ the tower of the Sint-Pieterskerk had collapsed in 1512
- ^ a Rhenish rod is in this calculation considered as 3.767358 meter
- ^ "Snellius biographies" (PDF), dwc.knaw.nl, retrieved 15 August 2019.
- ^ De Wreede, L. C. (2007). Willebrord Snellius (1580–1626): a humanist reshaping the mathematical sciences. Utrecht University
References
[edit]- Willebrord Snellius (1580-1626): a humanist reshaping the mathematical sciences, thesis of Liesbeth de Wreede, Dissertation Utrecht 2007
- N. Haasbroek: Gemma Frisius, Tycho Brahe and Snellius and their triangulations. Delft 1968.
- Struik, Dirk Jan (1970–1980). "Snel, Willebrord". Dictionary of Scientific Biography. Vol. XII. New York: Charles Scribner's Sons. ISBN 978-0-684-10114-9.
- "Snellius (Willebrord)". Nieuw Nederlandsch Biografisch Woordenboek. Vol. VII.
- O'Connor, John J.; Robertson, Edmund F., "Willebrord van Royen Snell", MacTutor History of Mathematics Archive, University of St Andrews
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Snell, Willebrord". Encyclopædia Britannica. Vol. 25 (11th ed.). Cambridge University Press. p. 293.
- Klaus Hentschel: Das Brechungsgesetz in der Fassung von Snellius. Rekonstruktion seines Entdeckungspfades und eine Übersetzung seines lateinischen Manuskriptes sowie ergänzender Dokumente. Archive for History of Exact Sciences 55,4 (2001), doi:10.1007/s004070000026.
External links
[edit]
- Willebrord Snellius at the Mathematics Genealogy Project
- Works by Willebrord Snellius at Open Library (in Latin)
- Works by or about Willebrord Snellius at the Internet Archive (in Latin)
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