In the 1970s and 1980s I had the pleasure(?) of making tract maps for two
counties -- Middlesex while I was Darrett Rutmans' graduate assistant, and
York when I worked at Colonial Williamsburg. Needless to say both were made
before the widespread availability of real mapping software. Actually the
York County map was eventually drawn on a CalComp plotter -- but we had to
"connect the dots"
My experience running tracts from patents to deeds to wills, etc. and back
and forth from 1630 to about 1820 is that magnetic declination isn't much of
a factor. Seventeenth and most eighteenth century surveyors were working in
compass points -- units of 11.5 degrees. which gives a fairly hefty margin
for error going in. Likewise, once bounds had been marked -- even in part
-- lines didn't move much. My favorite example is the Rosegill tract of the
Wormeley family in Middlesex. I sweated for several days with compass,
protractor and strait edge drawing a line of about 30 runs of 5-10 poles
each. It supposedly followed the main road in Middlesex. I couldn't wait
to see what my reconstruction on the tracing paper would look like when I
over-laid it on the topo map, and would you believe, the line dropped right
onto US 17 -- which hadn't moved more than 100 feet from the original
seventeenth century alignment until they began to rebuild it as four lanes,
divided in the 1960s?
Any table of declinations will show you that they change over time, but in a
more or less cyclical manner. The result is, when taking into account the
instruments of the day, that declination between 1650 and the 1970s when I
was doing most of this work came out just about the same.
The critical factor is if you can find landmark -- usually water in
Tidewater -- and get a base from that, then by running the meets and bounds
it will all work out. Of course the hard ones are the lines where you have
direction but no distance or vice-versa. It's a whole lot easier if you're
doing a larger area than just one or two tracts.
Let me also say that if you start from the notion that every surveyor in the
past was trying to do the best job they could with the tools they had at
hand, you won't be far from wrong. In the two counties I've worked on, over
two centuries in each county, I found virtually no evidence of fraudulent
work or even very sloppy work. Most errors are easily attributable to
errors in the copying over of the surveyors plats, the deeds, or whatever
into the county record books.
I would be happy to share my recollections and experiences with crating
tract maps with any who wish to contact me "off the list."
Peter V. Bergstrom, PhD
Manager, Information Systems, Lighthouse Institute
Archivist, Illinois Addiction Studies Archive
Chestnut Health Systems
720 W. Chestnut St.
Bloomington, IL
Webmaster http://www.chestnut.org
-----Original Message-----
From: Bibb C. Edwards [mailto:[log in to unmask]]
Sent: Wednesday, 22 August 2001 8:56 PM
To: [log in to unmask]
Subject: Magnetic North / GIS
I am attempting to retrace a parcel boundary described in a 1701 land
patent in what is now King William County on a modern USGS map.
Would anyone know : 1) whether true North or magnetic North would
have been used in the patent description, and 2) how many degrees of
declination between true north and magnetic north was observed in the
tidewater in 1701?
I would also like to correspond with anyone - privately is probably
better - who has had experience with this kind of project. Needless
to say, so far I am having some problems getting the polygon to
close. With 2 of the 13 reaches lacking a stated distance maybe I
should not be too surprised. But I am curious just how accurate these
300 year-old patent descriptions have generally proven to be.
I have also been trying to map the parcel using Geographic
Information System (GIS) software (ArcView) over an orthophoto of the
area in question. That leads to a related question. Are GIS systems
now being used in professional historical research? They seem to me
to be potentially very valuable in storing, presenting and sharing
spatial data.
Thanks for your help,
Bibb Edwards
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