Edmund Gunter (* 1581 in Hertfordshire, † December 10, 1626 in London) was an English mathematician and astronomer. He was known as the inventor of mathematical instruments and a precursor of the slide rule.
Gunter had Welsh roots. He attended Westminster School and from 1600 Christ Church College, Oxford University. After 1603 he remained at Oxford, was ordained in 1614 and was a preacher in 1615 a Bachelor's degree in Theology ( Bachelor of Divinity ). In 1615 he was rector of the church of St. George in Southwark and St. Mary Magdalen in Oxford - he had this post until his death. Since his youth he was interested in mathematics, discussed it with his friend Henry Briggs, and made such progress in this area, that he, on the recommendation of Briggs Professor of Astronomy at Gresham was 1620 College London, which he remained until his death. The post he owed the patronage of the politician John Egerton, 1st Earl of Bridgewater ( 1579-1649 ). Previously, he had applied unsuccessfully for the 1619 re- founded by Henry Savile Savile professorship at Oxford. Savile should thereby have expressed very derogatory about the mathematical tools with which he wanted to demonstrate its suitability and to the satisfaction of Savile did not correspond to the true teaching of geometry. The first Savile Professor of Geometry was Henry Briggs instead.
He invented various instruments, which were also under his name spread and published it. For example, a chain for surveying ( Gunter's chain called, 22 yards long with a division in 100) and an astronomical quadrant. A book about navigation appeared 1623rd His book about his proportional compass (Sector ) was published in 1606 in Latin (as in the preface to the later English edition wrote ), the English edition, in which he described several other of his instruments (like its forerunner of the slide rule ), was not published until 1624 in English. His books were widely spread.
Gunter invented 1620-1624 a precursor of a slide rule, a so-called " Logarithmenlineal ". Its logarithmic scales were placed on different devices and found as Gunter 's Line or in shipping Gunter 's Scale (or simply Gunter ) distribution. They had on one side the usual division, on the other hand, the logarithmic. By juxtaposing in the way of the slide rule calculations could thus be performed in trigonometry and navigation.
In his Canon Triangularum 1620 he published tables of logarithms of sines and tangents functions ( for every grade and every minute) to 7 decimal places. In later edition he added the values of the logarithms of the numbers from 1 to 1000 according to Briggs Arithmetica Logarithmica.
He led the words co- sine ( cosine of ) and co - tangent ( cotangent for ) a. On his scale (but not in his books ) he used sin for sine and tan for tangent. On the question of who should receive these abbreviations First, there are different views ( Albert Girard is this above).
Perhaps he also discovered the first 1620-1624 that the declination of the magnetic needle varies with time. For James I in 1624, he published a description of the sundials in the royal gardens of Whitehall.
- Canon Triangolorum, or Table of Artificial Sines and Tangents (1620 )
- Description and Use of the Sector, the Crosse - staffe and other instruments ( 1624, dated 1623), archives
- New Projection of the Sphere ( 1623)