Edmund Gunter

Edmund Gunter (1581–1626) was an English mathematician and instrument maker who developed logarithmic scales and surveying instruments used in navigation and practical calculation.

Logarithm: A mathematical function that converts multiplication into addition and division into subtraction. Logarithms made Gunter’s graduated scales useful for multiplying and dividing.
Gunter's scale: A logarithmically graduated ruler used with dividers to perform multiplication, division, and other calculations. This is Gunter’s best-known device for calculating without written logarithms.
Gresham College: An educational institution in London founded in 1597 that offered free lectures in subjects including mathematics. Gunter became professor of astronomy there in 1619.
Gunter's scale in navigation: The use of logarithmic scales and dividers to calculate navigational quantities aboard ships. Seamen used the scale to simplify computations involving courses, distances, and proportions.
Proportional compass: A hinged drafting instrument with paired scales for transferring proportional lengths and performing geometric calculations. Gunter helped popularize this instrument as a practical aid to calculation.
Gunter's chain: A measuring chain 66 feet long, divided into 100 links, used in land surveying. Its standard length made field measurements convenient to record and convert.
Henry Briggs: An English mathematician who developed common logarithms and helped establish their use in computation. Briggs’s logarithmic work formed part of the mathematical context for Gunter’s scales.
Gunter's chain in land measurement: The use of a standardized 66-foot chain for measuring fields and recording land areas. The chain became a durable unit in British and American land surveying.
Cross-staff: A surveying and astronomical instrument that measures angles using a graduated staff and sliding crosspiece. It belongs to the instrument-making tradition Gunter applied to surveying and navigation.
Gunter's quadrant: A graduated quadrant used to measure angles and solve practical surveying and navigation problems. It brought angular measurement into the same portable instrument tradition.

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William OughtredRelated: Gunter’s line enabled multiplication by measured distances before Oughtred joined scales into a rule.