Edmund Gunter

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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 forerunner of the slide rule .

Life

Gunter had Welsh roots. He attended Westminster School and from 1600 the Christ Church College of Oxford University . After 1603 he stayed in Oxford, was ordained, became a preacher in 1614 and received a bachelor's degree in theology (Bachelor of Divinity) in 1615 . In 1615 he became rector of the churches of St. George in Southwark and St. Mary Magdalen in Oxford - he held these posts until the end of his life. Since his youth he was interested in mathematics, discussed it with his friend Henry Briggs and made such progress in this field that he became professor of astronomy at Gresham College in London on the recommendation of Briggs in 1620 , which he remained until his death. He owed the post to the patronage of the politician John Egerton (1579–1649). Previously, he had applied in vain for the Savile Professorship in Oxford, newly founded by Henry Savile in 1619. Savile is said to have made very derogatory comments about the mathematical instruments with which Gunter wanted to demonstrate his suitability and which, in Savile's opinion, did not correspond to the true theory of geometry. Instead, Henry Briggs received the first Savile professorship in geometry.

Gunter invented various instruments, which were also used under his name, and published about them. For example, he designed a chain for land surveying (called Gunter's Chain, 22 yards long with a division into 100 parts) and an astronomical quadrant . A book on navigation appeared in 1623. His book on his proportional circle (Sector) appeared in Latin in 1606 (as he wrote in the preface to the later English edition); the English edition, in which he also described various other of his instruments (such as his predecessor the slide rule), did not appear until 1624. His books were widely used.

Between 1620 and 1624 Gunter invented a forerunner of the slide rule, a so-called "logarithm ruler". Its logarithmic scales were applied to various devices and were used as Gunter's Line or in the seafaring Gunter's Scale (or simply Gunter ). They had a linear division on one side and a logarithmic scale on the other. By placing them next to each other in the manner of a slide rule, trigonometric calculations for navigation could be carried out.

In his Canon Triangularum he published 1620 tables of logarithms of sine and tangent functions (for every degree and every minute) with an accuracy of 7 decimal places. In later editions he added the values ​​of the logarithms of the numbers from 1 to 1000 according to Briggs Arithmetica Logarithmica .

He introduced the terms co-sine (for cosine ) and co-tangent (for cotangent ). On his scales (but not in his books) he used "sin" for sine and "tan" for tangent. There are different views as to who first introduced these acronyms (they are also attributed to Albert Girard ).

He may also be the first to discover between 1620 and 1624 that the declination of the magnetic needle varies over time. For King James I , he published in 1624 a description of the sundials in the royal gardens of Whitehall .

In his honor, Mount Gunter in Antarctica has been named after him since 1962 .

Works

Trigonometric table from the Ciclopaedia 1728
  • 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), Archive
  • New Projection of the Sphere (1623)

literature

  • Florian Cajori : A history of the logarithmic slide rule and allied instruments and on the history of Gunter's Scale and the slide rule during the seventeenth century , 1909; Reprinted by Astragal Press, Mendham, New Jersey 1994.

Web links

Individual evidence

  1. ↑ In 1888 the captain Ludwig Jerrmann published the book Die Gunterscale in Hamburg and wrote that it was still widespread among seafarers at that time and was also used by Admiral Horatio Nelson .
personal data
SURNAME Gunter, Edmund
BRIEF DESCRIPTION English mathematician and astronomer
DATE OF BIRTH 1581
PLACE OF BIRTH Hertfordshire
DATE OF DEATH December 10, 1626
Place of death London