Surveying coordinates on a 1770 land grant

Asked September 26, 2014, 9:47 AM EDT

Hello,

I am attempting to read the coordinates on a small surveyor's map. The format it is written in doesn't seem to make sense as latitude/longitude. On one border it reads NW 30° 67' 04" and then N 60° 67' 04" on another border. It is located in South Carolina. The issue is the 67 in the minutes spot. From what I've read the minutes only go 1-60. I am wondering if it is written in an now unused format or maybe it isn't lat/long that it is describing. Any help is much appreciated. Below is the link to a photo of the map. Thank you!

http://www.archivesindex.sc.gov/onlinearchives/Thumbnails.aspx?recordId=104615

South Carolina

1 Response

You are correct on lat/long being in degrees, minutes and seconds. Lat/log is like a GPS position. It defines a specific point on the ground. The plat you sent shows a survey based on a bearing and and distance. Before we had the use of global positioning this is the way plats were done. Some are still done this way now. You would establish a known point. That might be a tree, coroner, iron rod, etc..... This position has no geographical reference. It is just a location/point on the ground that one could easily find. Then based off of the direction North they would shoot a bearing and distance. Basically they would take a compass and shoot a bearing and measure off a distance. So on one line you have a bearing of N 60 degrees and a distance of 67.04. and the second line is a bearing of NW 30 and a distance of 67.04. The distance is measured in chains. A chain was a steel tape that measured distance. One chain is equal to 66 feet. 10 sq chains equal an acre. So if you had 67.04 chains. Take 67.04 x 67.04 since the sides of the plat seem to be parallel. That equals 4,494.36 sq chains. Divide that by 10 and that equals 449.4 acres. The plat shows 450 acres so this would be accurate.

Please let me know if you have any more questions.
Derrick

Derrick Phinney
Clemson Extension
843-563-0135 x 3
dphinne@clemson.edu