Surveying

Jefferson's theodolite

In the early 18th century, much of Virginia’s western countryside was imperfectly known and poorly mapped. Surveyors[1] provided accurate descriptions that enabled the colonial government to grant out land to eager settlers. Peter Jefferson, Thomas’ father, worked as a surveyor and cartographer for most of his adult life. From 1745 until his death in 1757, he surveyed for the colony in one official capacity or another. Peter Jefferson’s more famous accomplishments included marking the location of the Fairfax line in 1746, extending in 1749 the boundary between North Carolina and Virginia, and helping produce in 1751 one of the first accurate maps of the colony of Virginia. He must have taught his son the finer points of surveying as he organized the fields of his Albemarle County farm.

In June 1773, Thomas Jefferson followed in his father’s footsteps when he received a commission as surveyor of Albemarle County.[2] Unlike his father, however, he discharged his duties through deputies and resigned the post the following year. When in 1778 he produced a sketch map of his native county, he did so for his own use, not for the public good.[3] Surveying for the younger Jefferson was primarily a tool for imposing order on his farms. Dozens of plats survive today from projects he undertook to rationalize and describe his lands in Bedford and Albemarle counties. In 1793, for example, Jefferson surveyed his fields in order to revise their boundaries in accordance with new schemes for crop rotation. An 1806 survey established a better route from the Rivanna River to Monticello, while a project in 1809 mapped the location of the farms and buildings within the fourth roundabout. Surveying for a Virginia planter was clearly a useful skill, one Jefferson believed subsequent generations of his family ought to continue to practice. At the age of 66, he ran chains through the woods on the slopes of Monticello in an attempt to teach some of his grandsons the rudiments of the profession.

Surveyors in Jefferson’s period required only two pieces of specialized equipment: a standard-length chain for measuring distance along a straight line and an instrument for calculating the angle between two distant objects. Jefferson’s surveying chain, called “Gunter’s chain,” was 66 feet in length. It was divided into 100 links, each 7.92 inches long. There were 80 chains in a mile, and 10 square chains equaled an acre. For the other tool, most surveyors used a special compass that the British called a “circumferentor.” Jefferson owned at least two such surveying compasses. In 1778, he acquired a more sophisticated instrument for the task, a theodolite produced by Jesse Ramsden. The Ramsden theodolite could turn angles in both the horizontal and vertical planes, which extended its utility beyond surveying. In 1815, for example, he employed it to determine the elevation of the Peaks of Otter in the Blue Ridge Mountains.

Primary Source References[4]

1806 Aug. 30. (Thomas Jefferson to John Lynch). "My father removed into this county I think in 1753, and was surveyor I should suppose about a year or two, when he was succeeded by John Dawson as principal and John Staples deputy; and after a short time Staples became principle. My father died in 1757, Staples having some time before received the books and papers of the Surveyor's office; so that they were not burnt in his house, that accident having happened 10. years after his death; nor as far as I know or believe have they ever been destroyed. They were safe I know in Bryan's time in whose hands I have seen the plat books and entry books of colo. Fry and Doctr. Cabell who I believe were among the first surveyors after the county was taken from Goochland; and I have no reason to doubt they are all now safe."[5]

Date unknown. (From Thomas Mann Randolph's Notebook). "In surveying to prevent droping [sic] a whole out, as it is called, or ten chains, which sometimes happens, let the boy who runs to the leader with the sticks cry out when he receives them, and the surveyor on hearing him shift a pin in his coat from the first button hole to the 2d. and so on counting downwards, leaving it at the bottom and beginning with another when he has got thro. the whole. This must be done by the hinder chain carrier (in the woods) when he delivers the sticks, as the surveyor might lose his object. The boy ought allso [sic] to have a bit of wood, and a penknife with which to notch it every time he delivers the sticks."[6]

Footnotes

  1. This article is based on Jay Boehm, Monticello Research Report, March 1998.
  2. PTJ 1:99-100.
  3. Ibid. 2:208.
  4. Please not that this list should not be considered comprehensive.
  5. Colonial Williamsburg. http://research.history.org/JDRLibrary.cfm
  6. University of Virginia, Small Special Collections Library, Accession #5150, p. 105.

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