# Famous Land Surveyors Throughout History

## Other than the THS Concepts team, of course…

Article By: Francesca Burke
Last Update: July 2019

You might not think there are any famous land surveyors, but lots of famous names and faces have contributed to the industry. Next time you’re at a dinner party, bring up the following names and sit back to bask in the room’s full attention…

## Leonard Digges

Leonard Digges was a 16th century English mathematician and surveyor, and the inventor of the theodolite. Theodolites use a telescope to measure horizontal and vertical angles. Nowadays theodolites are digital, highly accurate and integral to land surveying. Furthermore, they have been adapted for use in meteorology and rocket launches.

## William Roy

Scottish Major-General William Roy was an accomplished surveyor who worked closely on surveying projects within the British military. Roy advocated the use of new technologies, proposing a map establishing geographical coordinates of significant landmarks in order to draw maps and conduct surveys.

Between 1791 and 1853, the Principal Triangulation of Great Britain was carried out. The project used precise trigonometry to map the entirety of Great Britain and Ireland. In effect, Roy’s work signalled the beginning of the modern-day Ordnance Survey map.

A table of surveying from 1728, from Wikipedia

## Jesse Ramsden

Jesse Ramsden was a mathematician and maker of scientific instruments. Ramsden notably invented a new, more accurate type of theodolite for William Roy around 1785 which measured latitude and longitude separations. The ‘Ramsden theodolite’ contributed heavily to the Principal Triangulation of Great Britain.

## Edmund Gunter

Edmund Gunter was an English mathematician who invented ‘Gunter’s chain’, a measuring unit exactly 22 yards (around 20m) long and divided into 100 links. An area of 10 square chains equals one acre.

Gunter’s chain reconciled traditional English land measurements, which are based on the number four, and the system of decimals which is based on the number 10. Because an acre measures 10 square chains, land measurement can be computed in decimalised chains and links. It’s then converted to acres by dividing the results by 10. A ‘quarter chain’ (25 links) is known as a ‘rod’ or ‘pole’, while ten chains equal a furlong and 80 chains equal a statute mile. Even today, measurement of the public land systems in the USA and Canada is based on Gunter’s chain!

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