Jack A. Raudenbush, P.E., F.ASCE, your Region 2 Director is a member of the Central Pennsylvania Section. Jack will be representing you at the next Board meeting on October 27 and 28, 2020.
Visit an ASCE designed historic site! These sites illustrate the creativity and innovative spirit of civil engineers. Visit https://www.asce.org/landmarks to find sites near you. Share photos of your travels with me and I will post in Region 2 correspondence and on our Region’s social media pages.
The Mason Dixon Line
The Mason Dixon line, commonly referenced as the boundary between Pennsylvania and Maryland, also includes a portion of the northern boundary of West Virginia and the western boundary of Delaware. It was surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon. The Mason–Dixon line was marked by stones every mile 1 mile and "crownstones" every 5 miles, using stone shipped from England. The Maryland side says "M" and the Delaware and Pennsylvania sides say "P". The parallel (latitude line) was established as 15 miles south of the then southernmost point in Philadelphia.
Mason and Dixon started off with a crew of five, but by the time they got towards the end of the survey the party had grown to about 115. They thought at the end of the survey that the stones were accurate within 50ft. But what is realized today is that some of them are as much as 900ft off. The reason is not because Mason and Dixon were inaccurate in their execution nor because the equipment was faulty. It was actually gravity. Gravity had an impact on the plumb bob they were using. They had a 6ft telescope and it used a plumb bob on a fine wire. But gravity varied from location to location because of the influence of mountains.