JEFFERSON THE SURVEYOR
Poplar Forest Newsletter, Fall 2003

Jefferson had a life-long passion for surveying. He inherited his father’s maps and surveying instruments, and even served a short term as surveyor of Albemarle County. He created maps for his Notes on the State of Virginia, and proposed boundaries for western territories when Congress was considering the Ordinance of 1784.

Even later in life, Jefferson pursued surveying. In 1815, the 72-year-old Jefferson journeyed from Poplar Forest to survey the Peaks of Otter more than 30 years after he had surmised that they were the highest mountains in North America.

In some ways, Jefferson would be very much at home with surveying today. In other ways, he would be amazed at advances in the field.

Surveyors today employ the same principles as Jefferson. They measure distances and angles and use geometric principles to map boundaries and other features of the landscape. The major difference is that over the years, technology has allowed for much greater accuracy.

For instance, many of the maps of Poplar Forest have boundaries that shifted even during Jefferson's time as the surveys were redone. One Jefferson-period map shows an error of more than 100 feet, considered in his day a very accurate boundary. Today, a typical land survey is within .01 feet, or 1/8 inch.

In Jefferson’s time, surveyors used chains and compasses – which could be off by up to one-half degree – to measure distances. They also used a tool called a transit to measure angles. Near the end of Jefferson’s life, upgraded transits with telescopes –– not compasses— became more commonly used, boosting accuracy when computing more distant points.

By the mid-20^th century, transits employed lasers to increase the accuracy of gauging angles and distances. Poplar Forest archaeologists acquired a total station in 1998, which includes the laser as well as a computer to record information.

While a good surveyor today using a total station can lay out boundaries with at least the same accuracy as a surveyor using the Global Positioning System, the GPS makes the task easier and less expensive. Developed by the U.S. Department of Defense and now widely used by the general public, GPS employs 24 satellites that transmit signals to portable receivers with location information.

Again, the system uses the same principle as surveying in Jefferson’s time: take information on two or more known points and from that determine the location of the third, unknown point.

Poplar Forest’s GPS coordinates are 37.34826 North latitude and 79.26495 West longitude. It took two people collecting satellite information over a 24-hour period to establish these coordinates.