In several earlier posts, I discussed maps, map-making, surveying, and the tools and concepts necessary for the accurate measurement of land and geography to create accurate maps. Along the way, I’ve mentioned cadastral (i.e. real estate) mapping, but mostly I’ve talked about mapping the shape of the Earth and the shape of its lands, called geodetic mapping, which requires a reference scheme (longitude and latitude), geometric concepts and the tools to use the reference scheme and concepts. Greater accuracy in the tools developed over time, as well as some standards for the procedures for using them.
One function of surveys that I have not yet covered has been the setting of boundaries: not necessarily the boundaries between two or more properties, but between two politically different entities. Who set the boundary between France and Belgium, or between Belgium and the Netherlands? Was the boundary established via a survey? Actually, no: most boundaries were established by treaty and were specified in words, but I can only find mention of surveys in a very few cases. The words in the treaties lay out what the boundaries are, in some cases, such as defining a border as a specific river, the political entities on each side being granted half. In many cases, natural geographical features were used as boundaries, such as the water around the British Isles delineating the U.K. from the rest of the world. Setting borders is not measurement leading to discovery: instead, it is a form of engineering using standards and specifications to perform measurements, and results in something more or less useful.
One boundary that I know was put into place by a survey divides Pennsylvania and Maryland with the Delaware separated from both of them. This was done by a survey led by Charles Mason and Jeremiah Dixon – the Mason-Dixon line. I admit that I never thought about it very much until the novel by Thomas Pynchon came out, called Mason & Dixon. I read the book, enjoyed it, and have wondered how factual the story that Pynchon wrote was or is. Short of re-reading, it, though, I suggest that much of it is based on fact, since I know that Pynchon is reputed to be a thorough researcher, though there is plenty of room of Pynchon’s creative invention.
The genesis of the conflicting claims has to be laid to the way that both the colonies received their charters. The first, the charter for the Maryland colony, was given to the 2nd Lord Baltimore, Cecil Calvert, though the idea of it and its boundaries had been proposed by his father, George Calvert, the 1st Lord Baltimore, who died shortly before it was granted in 1632. The Calverts were Catholics in Anglican England, and George had proposed the colony to be a refuge for Catholics: essentially a way to put the “Catholic” problem out of sight and thus out of mind. The supporters of the already established colony of Virginia were not pleased by this, and they lobbied, mostly unsuccessfully, to eliminate the new colony. They were only successful in having the charter changed to reflect the fact that Virginia settlers were already in part of the territory originally granted to the Calverts.
While Cecil stayed in England to fight the Virginia challenge, he sent his younger brother, Leonard, to establish the colony and be its first governor. In the instructions that Cecil gave Leonard, he stressed that the colony needed to be established with religious tolerance as part of its principles, since the colonists originally sent were both Catholic and Protestant. In 1649, the assembly of the Maryland colony passed the first law requiring religious tolerance in the British colonies.
The establishment of the Maryland colony occurred during upheavals in England: in 1629, the King dissolved Parliament, the apparent start that undermined the stability of England, led to the three civil wars, the beheading of King Charles I, the dictatorship of Oliver Cromwell, and ultimately to The Restoration in 1660. A pretty tough 30 years or so for England, throughout most of which and at the end of which, the Calverts retained their proprietorship of Maryland.
The other charter, that of the area known as Pennsylvania, was granted to William Penn in 1681. It, too, has a background story: William Penn’s father, Admiral William Penn, had rendered services and financial backing to the restored monarchy, so despite young William’s radical Quaker faith, his arrests for proselytizing, etc., not only the King, Charles II, but the Duke of York, who became King James II at the death of Charles II, gave up territory for the charter. William, being a theological visionary with his head in the clouds, as it were, was not so well grounded that he paid close attention to the boundaries, and despite his charter granting him lands above the 40th parallel, established the city of Philadelphia below the 40th parallel. In Wikipedia, there is a wonderful map showing the approximate overlap of the two charters, as envisioned by the protagonists.1
The Maryland charter was supposed to cover all the land north of the Potomac River up to the 40th parallel, on both sides of Chesapeake Bay, east to Delaware Bay and the Delaware River. I have not discovered how the western border was specified.
The Pennsylvania charter was to be the land north of the 40th parallel from the Delaware River, south of New York and its western border was specified as a longitudinal line 5 degrees from the Delaware River.
For some reason, the three counties in the eastern part of the Maryland charter ended up as part of the Pennsylvania charter. They did not remain there for too long, though, since the settlers expressed a desire to be independent almost immediately after the new proprietor of Pennsylvania arrived, and were granted semi-autonomy in 1704. The town of New Castle in what became Delaware was the first established city in the region, and its borders figure in to the eventual settlement and surveying.
The dispute between the Calverts and the Penns remained unsettled, and led to violent clashes between settlers of both loyalties. It should be noted that the Pennsylvania charter area maintained religious tolerance, much like that put into law by Maryland, but Pennsylvania attracted disaffected and persecuted people from throughout Europe as well as from England, while it appears that Maryland mainly attracted English settlers.
In 1732, the 5th Baron Baltimore signed a provisional agreement with Penn’s sons, agreeing to a line between the colonies and giving up the claim to the three counties of Delaware, but later, he denied that the document had some of the terms he had agreed to. In 1750, a royal commission was set up, and one of the results was that in 1760 the Crown ordered the 6th Baron Baltimore to accept the 1732 agreement. (Seems like it was a good time for the British to establish clear boundaries in North America: the date nearly matches the end of the French and Indian war: Quebec conquered in 1759, Montreal capitulated in 1760, and the Treaty of Paris signed in late 1762.)
The resulting agreement specified the following:
- Between Pennsylvania and Maryland:
- The parallel (latitude line) 15 miles (24 km) south of the southernmost point in Philadelphia, measured to be at about 39°43′ N and agreed upon as the Maryland–Pennsylvania line.
- Between Delaware and Maryland:
- The existing east-west Transpeninsular Line from the Atlantic Ocean to its mid-point to the Chesapeake Bay.
- A Twelve Mile (radius) Circle (12 mi (19 km)) around the city of New Castle, Delaware.
- A “Tangent Line” connecting the mid-point of the Transpeninsular Line to the western side of the Twelve-Mile Circle.
- A “North Line” along the meridian (line of longitude) from the tangent point to the Maryland Pennsylvania border.
- Should any land within the Twelve-Mile Circle fall west of the North Line, it would remain part of Delaware. (This was indeed the case, and this border is the “Arc Line”.)2
The resulting line between Pennsylvania and Maryland follows the parallel at approximately 39 degrees 43′ N, depriving Maryland of about 17′ worth of land.
Charles Mason and Jeremiah Dixon led the survey, many of the details of which are found with embellishments in Pynchon’s Mason & Dixon. They started in 1763 and finished or stopped in 1767. Mason was an astronomer, and Dixon, a surveyor, which, based on the information I discussed in the earlier posts about geodetic surveys, seems like the appropriate mix of skills.
How does their measurement function for statecraft? Violence ceased between the two sides about the location of the border, but after they finished, the border came to symbolize not just the difference between Maryland and Pennsylvania, but the divide between the colonies that permitted slave-owning to the south and those that eschewed slave-owning in the north. While Penn himself did own and trade slaves, in his will, he granted his slaves their freedom upon his death. There were Quakers, though, who were more opposed aggressively to slavery, and led Pennsylvania to outlaw slavery in 1781. Obviously, measurement did nothing to contribute to or to oppose slavery, but it did provide a convenient demarcation between the territories.
In the work that Mason and Dixon did, they marked each mile with stones, and every five miles placed a crownstone – a vertical stone with four sides, with the Penn family coat of arms on the side facing Pennsylvania and the Calvert family coat of arms facing Maryland. Mason and Dixon ran their latitude line dividing Pennsylvania from Maryland for about 244 miles, but apparently were stopped short of completing the 5 degrees by hostile Native Americans. That job was completed in 1784 by other surveyors.
As a somewhat peculiar consequence to the job done by Mason and Dixon, their results appear to have triggered a completely different type of geodetic measurement, one beyond the engineering of borders. To check the accuracy of surveys of this sort, after completing the line in one direction, the surveyors repeat their procedures going back to the original starting point, and expect to see minor random errors. Instead, Mason and Dixon found systematic errors that were larger than the expected random errors, and systematic in the sense that they all went in the same direction. When they informed the British Royal Society of this, the systematic errors were recognized as a possible way to prove Newton’s theory of gravity, since the errors might be attributable to the gravitational pull of the Allegheny Mountains. Newton had raised the possibility of mountains having sufficient gravitational attraction to pull plumb-bobs away from vertical, but ultimately felt that this would be too difficult to measure.
The Royal Society was persuaded by the Astronomer Royal of the time, Nevil Maskelyne, to follow up on this by finding a relatively isolated, symmetrical mountain and using both astronomical sightings to establish vertical, and plumb-bobs to establish at numerous points on the mountain, how much the plumb-bobs varied from vertical, to measure the gravitational pull of the mountain. Then, using that information, the density of the earth could be extrapolated. Maskelyn hired Mason to find a suitable mountain to use, which Mason did, but he declined further participation in the project. The exercise was done using the mountain Mason found located in southern Scotland called Schiehallion between 1774 and 1776.
As a further aside, It seems that during the Peruvian adventure of the French geodeticists, they had tried the same kind of measurement using a volcano near Quito, Chimborazo, had found a deflection in their plumb-bobs of about 8 seconds of arc, but were unable to draw any conclusions other than that this proved that the Earth was solid, not hollow.
During the data gathering phase of the project, surveyors took thousands of bearings around more that a thousand points at various elevations on the mountain. A mathematician named Charles Hutton was given the task of crunching the data. To make sense of it, he drew lines connecting the points at the same elevations on the mountain where the bearings were taken, depicting for the first time the contour lines now used in relief maps. The results of his work were twofold: one, Newton’s theory of gravitation was proven to be correct; and two, a figure for the density of the earth of 4500 kilograms per cubic meter was derived, which is less than 20% less than the currently accepted figure of 5515 kilograms per cubic meter.
Measuring the density of the earth has little to do with statecraft or the engineering of borders to provide useful definitions of proprietorship. From the dates, it will be noticed that the measurement of Schiehallion occurred at about the beginning of the rebellion of the colonies, as described by the British at the time, which those of us in the United States call the American Revolution. The Mason-Dixon line had settled one conflict, with greater conflicts to come based on its location and symbolic meaning, but not because a measurement had been performed. Boundary disputes have led to war and violence far too often, and are usually settled when one side prevails, or when the combatants are exhausted, specified in treaties, with surveying that may be done somewhat afterwards. But that is not always the case, and the next post will discuss a measurement that led not just to violence, but colonial domination.