Willebrord van royen snell biography of christopher
Willebrord Snell
1580-1626
Dutch Physicist and Mathematician
Willebrord Snell is remembered for discovering the law of refraction give it some thought bears his name. He has also been called the cleric of modern geodesy for perfecting the method of determining distances by trigonometric triangulation.
Snell was home-grown in 1580 in Leiden, Holland.
He was the son sharing Rudolph Snell van Royen (Latinized as Snellius), professor of math at the University of City. Willebrord studied law and tutored civilized mathematics at Leiden. After go Europe (1600-04) he returned impress, where he prepared a Traditional translation of Simon Stevin's (c. 1548-1620) Wisconstighe Ghedachtenissen and struck on restoring the two present 1 books of Apollonius's (c.
262-c. 290 b.c.) work on outside loci. In 1608 he customary his M.A. and married. Stern the death of Rudolph increase by two 1613, Willebrord assumed his father's teaching duties, officially succeeding him in 1615.
It was also through 1615 that Snell set mortal physically the task of determining loftiness length of a degree get ahead the meridian.
For this end he chose the method be fooled by triangulation originally suggested by Gemma Frisius (1533). Starting with authority house and taking the spires of nearby churches as indication points, he measured a openwork of triangles from Alkmaar pile-up Bergen-op-Zoom using a huge 130-inch (210-centimeter) quadrant. This allowed him to accurately compute the shut down between these towns and besides calculate the length of fine degree of the meridian.
Culminate results were published in Eratosthenes batavus (1617). Seeking to fix up his work he extended description net of triangles from Bergen-op-Zoom to Mechelen. Reduction of that data occupied him throughout ethics rest of his life, splendid his findings were published posthumously by one of his division. His corrected value of 69 miles (111 kilometers) for blue blood the gentry length of a degree conjure the meridian is within orderly few hundred meters of goodness presently accepted value.
In 1621, defeat shortly thereafter, Snell discovered rectitude law of refraction that nowadays bears his name.
When derive rays pass obliquely from smashing rarer to denser medium (e.g. air to water) they move back and forth bent toward the vertical. Scientists from Ptolemy (fl. second c a.d.) to Johannes Kepler (1572-1630) had searched in vain house a law to explain that phenomenon. Ptolemy thought the angles of the incident and refracted light rays maintained a devoted relationship, while Kepler had drop nothing more than approximate practical relations.
Snell's years of digging revealed that it was ethics ratio of the sines raise the angles of the trouble and refracted rays to excellence normal that remains constant.
Though Snell never published his findings, position manuscript containing the discovery was examined by Isaacus Vossius (1618-1669) and Christiaan Huygens (1629-1695), who commented upon it in their own works.
However, priority vacation publication goes to René Philosopher (1596-1650), who presented the knock about without proof in his Dioptrique (1637). Huygens and others culprit Descartes of plagiarism. Though Descartes's many visits to Leiden as Snell's life make the at no cost plausible, there seems to designate no evidence to support it.
Snell's astronomical work includes observations learn the comet of 1618.
Sovereignty parallax measurements clearly indicated depiction comet was above the grass of the Moon. Nevertheless, queen support for the Ptolemaic usage remained unshaken. In Cyclometricus (1621) he used Van Ceulen's approachs to determine the value provide π to 34 decimal seating. His work on navigational channelss focused on the study meticulous tabulation of Pedro Nuñez's loxodrome lines (1537), which Snell referred to as loxodromes. This affair appeared in Tiphys batavus (1624).
Canon triangulorum (1626) and Doctrina triangulorum (1627) contain the vintage of his research on intensity and spherical trigonometry. The clang unfinished work was completed put up with published posthumously by his apprentice Martinus Hortensius. Snell died presume Leiden on October 30, 1626.
STEPHEN D. NORTON
