There have been significant advancements in surveying equipment since the 1700s. The common surveyor’s compass (circumferentor) had a brass body and used magnetic needles to determine angles, but it was prone to local magnetic deviations.
A 66-foot metal Gunter’s chain split into 100 links (with one link equaling 7.92 inches, or 0.66 feet) was used for manual distance measurement. In survey descriptions, twenty-five links equals 1 rod or pole (16.5 feet); 10 chains equals a furlong (660 feet).
The name furlong derives from the Old English words furh (furrow) and lang (long) and dates back at least to early Anglo-Saxon times.
It originally referred to the length of the furrow in one acre of a plowed open field. The furlong (furrow length) was the distance a team of oxen could plow without resting.
For larger measurements, 80 chains is equal to a statute mile – 5,280 feet – and 10 square chains is an acre, or 43,560 square feet. Early theodolites were used to measure horizontal and vertical angles.
In the 1770s Jesse Ramsden invented the dividing engine, a mechanized device that replaced hand-divided graduations to greatly improve precision.
Upcoming Event
An 18th century surveying demonstration with historian Michael Carver will take place at the Albany Institute of History & Art in Albany, NY on December 6th from 11 am until 2 pm, in partnership with the New York Association of Professional Land Surveyors (NYSAPLS).
Participants will employ the tools and techniques of the 18th century surveyor and actively measure and map a parcel of land, then use these measurements to draw maps and write property descriptions inspired by historic maps in the Albany Institute’s collection.
Philadelphia-based living historian Michael Carver, the Regimental Brewmeister, has more than 30 years of home-brewing experience and has portrayed Revolutionary-era life for more than 15 years. Drawing on his background as a chemist, brewer, and reenactor, he brings the crafts, technologies, and everyday experiences of eighteenth-century America to life through hands-on programs.
The New York State Association of Professional Land Surveyors is the primary professional society representing licensed land surveyors throughout New York State. Founded in 1963 as a membership corporation, it serves as a voice for the surveying profession, representing approximately 75% of the state’s licensed surveyors across 18 regional affiliated organizations.
Read More About Surveying in New York
Illustration: 18th century surveying.
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