Letters to the Editor

Still in search of …
I just finished reading the article, "Searching for the Fairfax Stone," (July/August 2000, pp. 39-45). It is an interesting story, but I have one problem with it. The last sentence of the fourth paragraph of the article states, " … connecting the sources of the Rappahannock and Potomac Rivers … " There is a map of the area on page 42 that shows a line drawn between these two points. My question is this, being that there are longer and wider tributaries for both rivers, what determines which branch is the source of the said river? I do know that in some cases, settlers could have arbitrarily chosen a branch before a land grant was described, but in earlier circumstances this is not the case. What is the general rule?
Unsigned

Langelan Replies
There's some great history behind THAT question! The 1746 Fairfax Line was the boundary between the Virginia Colony, which operated under its grant from the Crown, and the holdings of Lord Fairfax, who had inherited (through marriage) his own entire separate royal land grant, not considered at that time a part of Virginia. Like all colonial boundaries, it was in great dispute. That's because the decisions were made, and the descriptions written, in far-off England by well-intentioned officials making their best guesses based on hopelessly incomplete, incorrect maps of North America. Years prior to the survey, Lord Fairfax himself had journeyed to England and won a favorable (to him) decision from King and Privy Council about which tributary of the Rappahannock should be used. In 1736, ten years before the great survey, an exploration team that included surveyors and "gentleman commissioners" [lawyers] from both Lord Fairfax and the Virginia Colony traveled up the Rappahannock and Potomac Rivers. They determined and marked, with blazes on trees to everybody's satisfaction, both the beginning AND ending points of the line. A decade later, it was the daunting task of the 1746 crew to "connect the blazes," with a marked, measured straight line eighty miles long. Only one man, surveyor Benjamin Winslow, was present on both expeditions. Just FINDING the ten-year old blazes, and determining to the lawyers' satisfaction that they were the right ones, took the 1746 survey crew two exhausting weeks. Here's a small sample of what Thomas Lewis had to say about THAT part of the operation, in his inimitable journal of 254 years ago:

Saturday, 20th September:
The mountains made such a dismal appearance that John Thomas, one of our men, took sick and returned home… We set forward as soon as possible.
Rode out in the evening in order to discover which branch the surveyors of 1736 measured up, but could not be fully satisfied …

Sunday, 21th [sic] September:
The commissioners, surveyors and etc. spent most of the day [trying] to discover which branch made the headspring. Found some mark'd trees, but by whom was very uncertain. Returned to camp very fatigued. Several horses [seriously] hurt amongst the rocks on the mountain.

Monday, 22'd September:
As the commissioners could not be fully satisfied as to the proper place of beginning, they at length concluded to survey THREE sundry branches in order to discover the right [or main] branch. Col. Jefferson, Capt. Winslow, Mr. Brook and I went to the forks of said branches in order to survey them. Col. Jefferson and Capt. Winslow measured up the south branch, while Mr. Brook and I the north branch. The courses and distances followeth … [here he tabulates bearings and distances of approximately 1.7 miles] … Then we went back to the middle branch, beginning 18 poles above where we began before. Thence up the same … [more bearings and distances, another 0.8 miles] … to some marked trees. We then returned to camp and after plotting the several branches, presented the commissioners with a plan of the same.

Tuesday, 23d September:
The commissioners, not being fully satisfied and for better fixing the place of beginning, thought proper [that we] survey the RIVER from the Pocoson fork up to where we began before. Accordingly, Col. Jefferson, Capt. Winslow, Mr. Brook and I went down to said fork to survey the same. The west fork, by much the smallest, is the place called ‘Devil's Jump' … Thence up the main fork … [more bearings and distances follow, nearly 6-miles worth] … [After two days], we finished and got to camp about 12 o'clock.
[We] plotted the river and gave the commissioners a plan thereof.

Thursday, 25th September:
The commissioners at length agreed to begin at the head of the branch where the mark'd [trees] was found, that agreeing best with the plan of the former surveyors. We began accordingly at a Red Oak and 5 Cotton Trees, and ran from thence N 41 2/3 W, 110 poles to the top of the Blue Ridge … "

And the great survey of the line was underway at last.--C.L.

Etched in Stone
I enjoyed the article "Searching for the for the Fairfax Stone." Could the figure cut on the top of the stone, shown on page 44, be an arrow showing the direction of the line being run? Or, some other line being run? These are terrific articles. Keep them coming.
Don Scapuzzi
Via the Internet

Langelan Replies
The curious mark, a 6-inch square-cut with two extended sides, was found not on top of the stone but on its southeast face, a few feet above the ground. Located less than two paces from the headspring, source of the Rappahannock, the stone itself is as big as a refrigerator. There was speculation among the SHS searchers that it possibly marked the original 1746 Point of Beginning, although the old survey journal and field notes do not mention any marked stone at that point.—C.L.

Importance of Metadata
In his reply to Dave Doyle's letter (Letters to the Editor, June 2000, p. 57) Rj Zimmer says "Usually the metadata are in an ASCII or HTML file format, NOT embedded in the GIS theme because it is not GIS data; it is important, but extraneous information." I have to take issue with him on this statement—it isn't important—it's essential. I have just completed a series of e-mail correspondence on just this topic relating to oil and gas concession boundaries in a commercial GIS which has no coordinate definition information whatsoever. Failure to understand the underlying geodesy in such a situation can lead to costly mistakes and even international conflict. Mr. Zimmer's dismissive attitude toward the subject of coordinate system definitions is, unfortunately, all too common in the GIS business.
Ian Douglas
Via the Internet

Zimmer Replies
Mr. Douglas has gotten the wrong impression about my view of metadata. Possibly my use of the word "extraneous," which has many meanings, has misled him. My use of the word "extraneous" in my response to Mr. Doyle was in the sense "coming from the outside," because as I had stated, metadata are not embedded into the GIS data model, but are a separate document. Fully FGDC compliant metadata is a lot of information that one NEEDS but not information that one uses for GIS analysis, query, or display. In my GIS columns I have been beating the drum for metadata and will continue to do so, because as I stated in my response to Mr. Doyle, "metadata is important." Any GIS person who shares information with other agencies (public or private) has an appreciation for metadata. The example that Mr. Douglas gives, regarding projections and coordinate systems, is just one of the many metadata content categories. Others include currency of the data, accuracy of the attributes, scales for which the data are appropriate, contact information, data sources and many more, all of which help us to understand and evaluate the GIS data's usefulness.—Rj.Z.

Computation Questioned
In the article, "A View from the Top" (May 2000, pp. 6-8), Dr. Joseph Senne has a very interesting concept to compute the height of a mountain. If we follow his computational approach to put Mt. Chimborazo in Ecuador higher than Mt. Everest along the Nepal and China border by about 2.22 km, then the mean sea level at the equator will become higher by about 21 km as compared to that near the North Pole. In geodesy, we know that sea level has a "slope" of about a meter, but a difference of 21 km would be very difficult to accept.
Muneendra Kumar
Montgomery Village, MD

Senne Replies
It is well-known that the equator is about 21km more distant from the earth's center than are the poles. This oblateness of the earth is due to its rotation and was mathematically determined by Isaac Newton, who published it in his Principia of 1687 as a ratio of 230 to 229 or a flattening of 1/230 (the GRS80 spheroid has a flattening of about 1/298.25). The rotation creates a centrifugal force which acts perpendicular to the axis of rotation and increases from zero at the poles to a maximum at the equator. This is why a 190-pound person weighs 1 pound less at the equator than at the poles. This force (or effect) can be broken into two components: the lifting effect which is opposite to the direction of gravity and the sliding effect that is tangent to the surface and acts toward the equator. Throughout the eons, the earth has assumed this shape in which the sliding effect is compensated by the uphill climb toward the equator. This is what keeps all the ocean waters from accumulating at the equator. The shape is known as the geoid, or mean sea level, and is somewhat irregular because the earth is not quite homogeneous. Therefore, it is approximated with an ellipsoid such as the GRS80 or WGS84. The difference between the ellipsoid and the geoid is known as the geoid height. My article was really written with "tongue in cheek," designed to look at "highest" in a different way. I had hoped that the readers would see it like this and get a chuckle out of it. Elevations will always, of course, continue to be measured from mean sea level. Incidentally, in checking other mountains, it was found that Mt. Huascaron in Peru and Mt. Kilimanjaro in Tanganyika are both more distant from the earth's center than Mt. Everest. This makes Everest a distant fourth by this definition.—J.S

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