City of Alexandria, VA
Page updated Dec 6, 2010 5:49 PM
District survey used era’s best tools
August 1, 1996
by Pamela Cressey
As I discussed last week, the survey to delineate the boundaries of the federal district began in Alexandria at Jones Point. Andrew Ellicott came from Philadelphia to oversee the survey which would establish the 10 mile square District of Columbia in 1791. Enduring cold, heat, illness, political disputes, confiscation of his notes, and untrained crew, Ellicott completed the survey as well as L’Enfant’s plan for Washington in 1793.
An interesting Alexandria note is that the assistant surveyor for the Washington, James Dermott, was selected due to Dr. David Stuart’s influence. Both men were Alexandrians. Stuart was one of the district commissioners, while Dermott was a young Irishman and teacher of mathematics at the Alexandria Academy. Apparently there were problems between Dermott and Ellicott’s supervisors, which led to the commissioners siding with Dermott. Ellicott eventually left to survey in Pennsylvania while Dermott conducted the survey to divide blocks into lots.
The district survey was not the standard land survey recorded in courthouse deed books. These surveys were conducted using chains and compass which provided distances and degrees. Waterways, trees, rocks and other natural features were often used as starting points to measure from. Beth Mitchell discusses in her book, "Beginning from a white oak ...", that surveys for early land patents used a ship compass. A needle course was used, rather than a true meridian course. Thus, the boundaries were disputed as the earth’s magnetism changed. She notes that the declination changes about 2 degrees and 12 minutes every 40 years.
In contrast, the D.C. survey was high-tech for its time. Rather than basing the four corners of the 10-mile square on compass points, Ellicott used astronomical methods. Latitude was determined by observing starsas they moved overhead. Although Ellicott did use a compass for points between the four corners, his survey of these boundaries met the highest standards of its day in either America or Europe.