Water Under the Bridge

By John F. Oyler
Copyright © 2016



Mason Dixon Line
November 17, 2016



On another lovely Autumn Saturday I drove to “the Original Mason-Dixon Historical Park”, in Core, West Virginia, to participate in a short hike to the point where surveyors Charles Mason and Jeremiah Dixon crossed Dunkard Creek for the third time, prior to ending their monumental survey at the peak of nearby Brown’s Hill.

The park is jointly owned by Monongalia County, West Virginia, and Greene County, Pennsylvania. This particular event was the 249th anniversary of the termination of their survey; there are plans to have a major festival next year to celebrate the milestone anniversary.

Finding the Park was an adventure. I had no difficulty going down I-79 and getting into Mt. Morris. There are only five ways to get out of the village – it took me three false starts to find the one that led to the Park. The effort was worthwhile.

We have written several columns previously regarding the Mason-Dixon Line survey, but a brief summary is still relevant. The necessity for the survey was a long-standing dispute between the colonies of Pennsylvania and Maryland regarding the location of the border between them.

The misunderstanding occurred because of ambiguities in the charters originally given to the Penns and Calverts, proprietors of the respective colonies. The Crown’s basis for awarding charters was a map produced years earlier (1612) by John Smith, which indicated that the latitude of the northern end of Chesapeake Bay to be forty degrees. The current latitude is about thirty nine and a half degrees – an error of about thirty five miles.

In 1681 King Charles I granted a charter to William Penn granting him land described as "The said Lands to extend westwards five degrees in longitude, to bee computed from the said Easterne Bounds”. Based on Smith’s map, the southeastern corner of Pennsylvania (Easterne Bounds) was defined as being the intersection of the fortieth parallel and a circular arc with its center in New Castle, Delaware, and a radius of twelve miles. Since the fortieth parallel is much farther than twelve miles north of New Castle, the two lines never meet.

In fact, when a proper survey was finally made, it turned out that the fortieth parallel actually passed through Philadelphia, the large city that Penns had constructed, assuming it was well within their territory. The dispute between Pennsylvania and Maryland continued for many years until the parties settled on a compromise, an east-west line at a latitude fifteen miles south of the southernmost building in Philadelphia.

This line would indeed intersect the arc defining Delaware’s boundary with Pennsylvania, which had never been correctly surveyed. Eventually the proprietors hired Mason and Dixon to bring a kit of “leading edge” astronomical and surveying tools from England and perform a survey that would settle the issue permanently. They arrived on November 15, 1763 and immediately went to work. My son John reminded me that this journey has been commemorated by Mark Knopfler’s song “Sailing to Philadelphia”.

Mason was the assistant to Royal Astronomer James Bradley at the Greenwich Observatory, a skilled astronomer. Dixon was an accomplished surveyor who had worked with Mason before, on an aborted effort to record a transit of Venus across the sun, in Sumatra. In addition to surveying instruments and astronomical telescopes, their equipment included a precision chronometer based on the clock developed by John Harrison, the heralded winner of Parliament’s 20,000 pounds prize for conquering the challenge of determining longitude.

Their first task was to resolve confusion regarding Delaware’s boundary with Maryland. They then precisely established the latitude of the southernmost point in Philadelphia. Next they surveyed a line due west thirty one miles to Embreeville, Pennsylvania, where they established an observatory and set a reference stone, eventually dubbed “the Stargazer’s Stone”; it is still in existence.

From there they surveyed due south fifteen miles and established the correct latitude of the Mason-Dixon Line (39 degrees, 43 minutes, 17.4 seconds). They then proceeded to survey an east-west line by laying out a series of chords of a great circle comprising ten minutes of arc (about twelve miles long) intersecting the parallel. At the end of each chord, astronomical observations were made to determine the true position of the parallel.

The survey of “the West Line” began on April 5, 1765.By early October they had surveyed about 117 miles and had passed Conococheague Creek in what is now Franklin County, Pennsylvania. At this point they retraced their route eastward, establishing correct boundary posts on the parallel.

Surveying began again in early April 1766, following the same procedure. They proceeded up and over South Mountain, North Mountain, Sideling Hill, and Great Warrior Mountain, reaching the 165 milepost before returning east to set boundary posts and perform some additional surveying in Delaware. A note in their journal reports that they had passed the narrowest part of Maryland, with the Potomac River only a mile and a half south of the parallel.

Surveying in 1767 was delayed until July 13, mostly because of concern regarding permission from the Iroquois to proceed west. At this point they were joined by eleven Mohawks, three Onondagas, and interpreter Hugh Crawford. They reached the top of Savage Mountain (Allegheny) at 168 miles and Braddock’s Road at 189 miles.

By September they had crossed the Youghiogheny River, Cheat River, and the Monongahela River, each of which was shallow enough to wade across. On October 9 they were advised by the leader of their Indian escort that they had reached the limit of the area controlled by the Iroquois and that they should now turn back, lest they anger the Shawnee and Delaware Indians who controlled the lands to the West.

Mason and Dixon concluded their survey at the top of Brown’s Hill, just beyond Mile Post 233 on October 15, took astronomical readings there, and made the necessary corrections. They then turned back eastward and concentrated on setting boundary posts at the correct locations. The next summer the two surveyors stayed in the colonies until September, performing research on the dimensions of the earth on behalf of the Royal Society.

The coordinator of the event was an enthusiastic volunteer named Peter Zapadka. He gave a brief summary of the Mason-Dixon Survey, focusing primarily on their activities at its western extremity, then led us on a short walk to the point where the line crossed Dunkard Creek for the final time. We were accompanied by Doug Wood, a Native American re-enactor portraying a Cherokee brave named Ostenaco.

When we reached the meadow adjacent to Dunkard Creek, Ostenaco was hailed by four other re-enactors led by Don Robey, portraying a Delaware chief named Tingooqua. This quickly attracted my attention, as I knew Tingooqua as Catfish, for whom Catfish Camp and the Catfish Path were named. The additional information I gained from this experience will be the subject of a future column.

The encounter with the Delawares was a simulation of a real meeting between the Delawares and the Mason-Dixon party two hundred and forty nine years ago, a meeting which probably contributed to the decision to terminate the survey at Brown’s Hill.

The 250th anniversary celebration next October is a project that deserves our support. It promises to be educational as well as entertaining, featuring re-enactments of the surveying operation as well as their contact with the Native Americans, demonstrations of surveying and astronomical procedures and equipment of the time period, and the usual complement of food and vendor booths.

All told, it was an excellent experience in a lovely setting on a perfect Autumn day. A friend of mine, Norm Voigt, who is a legitimate expert on the history of surveying, had joined me at the Park. Afterwards we drove back into Mt. Morris where we had lunch at a delightful restaurant, Rising Creek Bakery.

Water Under the Bridge

  • "Water Under the Bridge" is a column written by historian John Oyler. It appears weekly in the Bridgeville Area News, a TribTotal Media publication, as well as in a more expanded form on his blog.

The Author

  • Aside from being Bridgeville's foremost historian, Dr. John F. Oyler is also an associate professor at the Univeristy of Pittsburgh, where he teaches classes in civil engineering.

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