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Willebrord Snellius, Mathematician 






Willebrord Snellius, Mathematician > Website
Willebrord Snellius (born Willebrord Snel van Royen) was a Dutch astronomer and mathematician, most famous for the law of refraction now known as Snell's law. Snellius was born in Leiden, Holland. In 1613 he succeeded his father, Rudolph Snel van Royen (1546–1613) as professor of mathematics at the University of Leiden. In 1615 he planned and carried into practice a new method of finding the radius of the earth, by determining the distance of one point on its surface from the parallel of latitude of another, by means of triangulation. His work Eratosthenes Batavus ("The Dutch Eratosthenes"), published in 1617, describes the method and gives as the result of his operations between Alkmaar and Bergen op Zoom—two towns separated by one degree of the meridian—which he measured to be equal to 117,449 yards (107.395 km). The actual distance is approximately 111 km. 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 that is named after him in 1621. The lunar crater Snellius is also named after him.














Eratosthenes, Measuring the Earth
Eratosthenes of Cyrene was a Greek scholar who lived and worked in Cyrene and Alexandria. Eratosthenes was director of the famous library in Alexandria, and is known for numerous important contributions to mathamatics, geography, and astronomy. In pa... 






Ptolemy, Astronomer / Geographer
Ptolemy was a Roman citizen of Greek or Egyptian ancestry. He was a mathematician, astronomer, geographer, astrologer and a poet of a single epigram in the Greek Anthology. He lived in Egypt under the Roman Empire. Ptolemy was the author of several s... 






Christiaan Huygens, Dutch Scientist
Christiaan Huygens came from an important Dutch family. Huygens's first publications in 1651 and 1654 considered mathematical problems. The 1651 publication Cyclometriae showed the fallacy in methods proposed by Gregory of SaintVincent, who had clai... 






Delambre, The Metric System
In 1795 Jean Baptiste Joseph Delambre was admitted to the Bureau des Longitudes, becoming President in 1800. In 1801 he was appointed secretary to the Académie des Sciences making him the most powerful figure in science in France.
In 1790 The Aca... 



















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