Edmund Gunter

Background

Gunter was born in Hertfordshire, England, in 1581.

Education

He was educated at Westminster School and Christ Church, Oxford, graduating B. A. in 1603 and M. A. in 1605.

He subsequently entered holy orders, became rector of St. George’s, Southwark, in 1615, and received the B. D. degree later that year.

In March 1619 he became professor of astronomy at Gresham College, London, retaining this post and his rectorship until his sudden death at the age of forty-five.

Career

Gunter’s contributions to science were essentially of a practical nature.

A competent but unoriginal mathematician, he had a gift for devising instruments which simplified calculations in astronomy, navigation, and surveying; and he played an important part in the English tradition—begun in 1561 by Richard Eden’s translation of Martin Cortes’ Arte de navegar and furthered by William Borough, John Dee, Thomas Harriot, Thomas Hood, Robert Hues, Robert Norman, Edward Wright, and others—which put the theory of navigation into a form suitable for easy use at sea.

Gunter’s works, written in English, reflected the practical nature of his teaching and linked the more scholarly work of his time with everyday needs; the tools he provided were of immense value long afterward. Gunter’s first published mathematical work was the Canon triangulorum of 1620, a short table, the first of its kind, of common logarithms of sines and tangents.

Gunter solved such problems as finding the sun’s amplitude from its declination and the latitude of the observer by additing similar scales to the seaman’s cross-staff.

Comparison of the amplitude with the sun’s direction, measured by a magnetic compass, was known to give the compass variation; but although Gunter’s own observations in 1622 at Limehouse were about five degrees less than Borough’s 1580 results there, a statement of the secular change of variation awaited the further decrease observed by Gunter’s Gresham successor, Henry Gellibrand. Gunter’s other inventions may have included the so-called Dutchman’s log for measuring a ship’s way.

Henry Briggs acknowledged his suggested use of arithmetical complements in logarithmic work and the terms cosine, contangent, and such are probably Gunter’s own; his use of the decimal point and his decimal notation for degrees are to be noted.

Gunter’s chain, used in surveying, is sixty-six feet long and divided into 100 equal links, thus allowing decimal measurement of acreage.

Largely following Willebrord Snell, Gunter took a degree of the meridian to be 352, 000 feet; this decision gave English seamen a much improved result.

Achievements

• He is best remembered for his mathematical contributions which include the invention of the Gunter's chain, the Gunter's quadrant, and the Gunter's scale.

Works

More photos

• book

  • The Description and Use of the Sector, Crosse-Staffe, and Other Instruments: With a Canon of Artificiall Sines and Tangents, to a Radius of 10000. ... and Fortification, &C (Classic Reprint)

    (Excerpt from The Description and Use of the Sector, Cross...)

  • The description and use of a portable instrument, vlugarly sic known by the name of Gunters quadrant by which is perform'd most propositions in ... ascention, and declination of the sun (1685)

    ( EARLY HISTORY OF ASTRONOMY & SPACE. Imagine holding his...)

  • The description and vse of the sector, the crosse-staffe and other instruments for such as are studious of mathematicall practise. (1624) by Edmund Gunter (2010-12-29)

Connections

friend/colleague:

Henry Briggs