**Edmund Gunter** was an English clergyman who published trigonometric tables and was important in the development of the slide rule.

- Edmund attended Westminster School as a Queen's Scholar, then entered Christ Church, Oxford on 25 January 1600.
- Already as an undergraduate, Gunter had developed a strong interest in mathematics and in mathematical instruments.
- Continuing his studies at Oxford, Gunter was awarded an M.A. in 1606 but he remained at Oxford until 1615 when he received the divinity degree of B.D. on 23 November.
- Gunter was ordained and in 1615 became Rector of St George's Church in Southwark and of St Mary Magdalen, Oxford.
- Gunter became a friend of Briggs, and would spend much time with him at Gresham College discussing mathematical topics.
- He died on 4 November 1613 and Briggs supported Gunter to be appointed as the second Professor of Astronomy at Gresham College.
- However, Gunter failed to gain the appointment which went to Thomas Williams.
- Thomas Williams had entered Christ Church in 1599, only one year before Gunter, so could not have had much greater experience.
- However, by 1618 Gunter must have spent so much time at Gresham College that William Oughtred believed that he was already a professor there.
- Gunter was appointed to fill the vacancy on 6 March 1619, two days after Williams resigned, largely on the recommendation of Briggs.
- The first person Savile interviewed for the professorship was Gunter.
- We must point out that if this is true, then certainly Seth Ward learnt this story from others since he was only two years old when Savile interviewed Gunter.
- Although the words sine and tangent were already in use, Gunter invented the words cosine and cotangent.
- This was the first ever publication of logarithms of trigonometric functions and Gunter deserves much credit for this innovation.
- He made a mechanical device, Gunter's rule, to multiply numbers based on the logs using a single scale and a pair of dividers.
- It was called the 'gunter' by seamen and was an important step in the development of the slide rule.
- Gunter published his description in 1623 in Description and Use of the Sector, the Crosse-staffe and other Instruments.
- It is worth noting that in this work Gunter uses the contractions sin for sine and tan for tangent in his drawing of his scale although not in the text of the book.
- What singles out Gunter's sector is that it is the first mathematical instrument to be inscribed with a logarithmic scale to facilitate the resolution of numerical problems.
- Such a rule is frequently referred to as a Gunter line.
- Gunter was the inventor of instruments but he needed an instrument maker to produce them.
- Elias Allen (1592-1653) who had his workshop beside St Clement Danes Church, the Strand, London, was the instrument maker whom Gunter used.
- Gunter gained from having Allen make his instruments and the illustration of the sector in Description and Use of the Sector, the Crosse-staffe and other Instruments is from plates engraved by Allen.
- But the relationship between the two worked the other way round too, for Allen made use of this engraving of Gunter's sector to advertise his own business.
- Gunter also invented 'Gunter's chain' which was 22 yards long with 100 links.
- Gunter also studied magnetic declination and was the first to observe the secular variation.
- Gunter died at Gresham College and was buried one day later in the churchyard of St Peter-le-Poer, Old Broad Street.

Born 1581, Hertfordshire, England. Died 10 December 1626, London, England.

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Analysis, Astronomy, Geometry, Origin England

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive