Philadelphia Reflections

Pennyslvania's Boundary: David Rittenhouse, Hero, Lord Baltimore, Villain

David Rittenhouse

In the Twenty-first Century, when we know how every American creek and river run, we can see it might have been simple to establish a boundary between the new royal grant to William Penn, and an earlier grant to Lord Baltimore by the then-reigning king's father, Charles I. Essentially: Penn got the Delaware Bay and a lot of wilderness to the west of it. George Calvert, Lord Baltimore, had long held the top half of the Chesapeake Bay and a strip of wilderness to the west of that. Two bays, with two hazy strips of wilderness attached.

George Calvert, Lord Baltimore

At what is now Odessa, Delaware, those two bays are only five miles apart; compromise should have settled the issue quickly. Two English gentlemen could have sat down over a pipe and a brew, working something out. However, the English nation was then changing kings, beheading them over matters of religion. A Roman Catholic, Lord Baltimore probably thought an opportunity might emerge from the turmoil if he stalled until matters went his way, since next in line of succession was James, Duke of York, who was a Catholic. But matters fall into the hands of the lawyers when principals of an argument are unable to speak. As we noted elsewhere, in the legal system of the day the last word from the last king was what counted in law courts, accepting any uncertainty about future latest words from future latest kings in order to maintain immediate peace. To lawyers of the time, all this talk about justice, fairness, and geometry was idleness when the nation needed order and stability. So the Calvert family lawyers over the course of eighty years, introduced one specious proposition after another that turned other lawyers purple with rage. Penn's lawyer, Benjamin Chew, beat them at this game, and his mansions in Delaware and Germantown attest to the value attached to this achievement. In other circumstances, posturing might have led to war, as it did in similar disputes with Connecticut. Penn probably knew better, but it takes two to compromise.

Mason-Dixon Line

It must be admitted that honest confusion was possible. Sometimes, a line of latitude was a line in the sense Euclid intended: all length and no width. At other times, lawyers and kings were talking about "parallels" as if they were strips, roughly sixty miles wide. If a sixty-mile strip was intended, it was important for a grant to specify whether it extended to the southern edge of the strip, or to the northern edge. But in fact, the state of science in the Seventeenth Century contained uncertainty about both where the strips were, and how wide. And if the grant's language didn't even make it clear whether the parties were talking about strips or width-less lines, eighty years could be a comparatively short time for a court to decide the case. To be fair to Lord Baltimore, many people at the time didn't think these matters were capable of fair solution, so the traditional way of dealing with land disputes was either by force or by craftiness.

David Rittenhouse Birth Place

In William Penn the folks from Maryland were, unfortunately, dealing with a friend of the King, who had one of the most brilliant mathematicians in Western civilization as his adviser. David Rittenhouse may have been born in that little farmhouse you can still visit on the Wissahickon Creek, and made his living as a clockmaker, but his native talents in mathematics, astronomy surveying, and instrument construction were so deep and so varied that later biographers are reduced to describing him merely as a "scientist" and letting it go at that. If you want to sample his talents, spend an hour or two learning what a vernier is, and then see if you could apply that insight, as he did, to a compass. So, as it turned out, Rittenhouse was able to describe a twelve-mile circle around New Castle, Delaware, construct a tangent that divides the Delmarva's Peninsula in half, and match it up with an east-west line we now call the Mason Dixon Line. When they finally got around to laying these lines on the ground, Mason and Dixon cut a twenty-four-foot swath through the forest, using astronomical adjustments every night, and laying carved marker stones every fifth of a mile for hundreds of miles. The variation from the line devised by Rittenhouse was at most a fifth of a mile off the mark; the intersection with the north-south line between Maryland and Delaware was less successful. The survey by Mason and Dixon was not quite completed to the Ohio line because the Indians, curious at first, eventually became wild with suspicion at such behavior, particularly the part about going out and aiming cannons at the sky every night. It seems likely that George Calvert, Lord Baltimore, had no more confidence in this madness than the Indians did.

So, the next time you take the train from Philadelphia to Washington DC, reflect that strict reading of the words in the land grants did admit the possibility that your whole trip could either have been within the State of Maryland, or else in the Commonwealth of Pennsylvania, depending on whether lawyers, or scientists, had triumphed in this dispute. Since the Mason Dixon Line later divided not merely two states, but two violently opposed cultures, Rittenhouse must stand out in the history of one of those people who were so smart that most people couldn't understand how smart he was.

Originally published: Monday, June 26, 2006; most-recently modified: Friday, May 31, 2019