Hello Clifford,
I am a surveying engineer and I recall one of my surveying
professors telling us about the surveying of the Canada-US border along the
49th parallel. Below is a snippet from Wikipedia
(http://en.wikipedia.org/wiki/49th_parallel_north) that explains what I recall
my professor told us, but in my own words, the surveyors in the 1800’s could
not measure accurately enough to place the boundary monuments exactly on the
49th parallel. Both countries have agreed to accept the location of the
original boundary monuments as the international boundary. The info below from
Wikipedia indicates some monuments up to ½ mile from the 49th parallel.
Parts of the 49th parallel were originally surveyed using astronomical
techniques that did not take into account slight departures of the Earth's
shape from a simple ellipsoid<http://en.wikipedia.org/wiki/Ellipsoid>, or the
deflection of the plumb-bob<http://en.wikipedia.org/wiki/Plumb-bob> by
differences in terrestrial mass. Although the surveys were subject to such
limitations of early to mid 19th-century technology, extremely accurate results
were obtained. However, in some places the surveyed 49th parallel is as much as
several hundred feet from the actual geographical 49th parallel for the
currently adopted datum<http://en.wikipedia.org/wiki/Datum_(geodesy)>,
WGS84<http://en.wikipedia.org/wiki/WGS84>. The Digital Chart of the
World<http://en.wikipedia.org/wiki/Digital_Chart_of_the_World> (DCW), which
uses the Clarke 1866 ellipsoid, reports the border on average at latitude 48°
59′ 51″ north, roughly 270 metres (886 ft) south of the modern 49th parallel.
It ranges between 48° 59′ 25″ and 49° 0′ 10″ north, respectively 810 metres
(2,657 ft) and 590 metres (1,936 ft) on either side of the average. In any
case, the Earth's North Pole moves around slightly, notionally moving the 49th
and other parallels with it; see polar
motion<http://en.wikipedia.org/wiki/Polar_motion>.
As per treaty, lines between original established monuments (1861) are straight
lines on the chord, rather than curved lines on the tangent, which generally
keeps the boundary some distance from 49 degrees north.
In 1909 the United States, United Kingdom and Canada signed and ratified a
treaty confirming the original survey lines as the official and permanent
international border. Nevertheless, the difference of the survey from the
geographical 49th parallel was argued in front of the Washington Supreme
Court<http://en.wikipedia.org/wiki/Washington_Supreme_Court> in the case of
State of Washington v. Norman, under the premise that Washington did not
properly incorporate the portions of land north of the geographical 49th
parallel, as laid out by detailed
GPS<http://en.wikipedia.org/wiki/Global_Positioning_System>surveying. The court
decided against the premise, ruling that the internationally surveyed boundary
also served as the state boundary, regardless of its actual position.
Bernie.
--
Bernie Connors, P.Eng
Land Information Infrastructure Unit, SNB
[email protected]<mailto:[email protected]>
From: Clifford Snow [mailto:[email protected]]
Sent: Tuesday, 2012-09-18 00:16
To: [email protected]
Subject: [Talk-ca] (no subject)
I'm doing some work in the Washington State and noticed some problems along the
border between BC and Washington State. I asked for help on the talk-us mailing
list.
I originally though the border was incorrect. However, because the border
doesn't track exactly along the 49th parallel there appears to be some
administrative areas that don't match up with the actual border. See
http://www.openstreetmap.org/?lat=48.9803&lon=-121.7579&zoom=12&layers=M
Paul Norman wrote:
On Mon, Sep 17, 2012 at 5:49 PM, Paul Norman
<[email protected]<mailto:[email protected]>> wrote:
The survey points are based on IBC data (which they view as PD) and are
supposed to be accurate within a few cm and the limits of NAD83 to WGS84
conversion (a few more cm).
I’ve verified a few by the lower mainland with survey and against a few sources
of accurate imagery and their data seems accurate within the limits of the
imagery.
You can see a clearing along parts of the border in that area so it’s accurate
to within 20 meters.
I know that Washington State argued that they were not responsible for the
border costs in Blaine because it was not part of the state since the state
ended at the 49th parallel and the border is north of the 49th there.
What I’ll do is go and eliminate duplicate border ways, like I did with the
lower mainland.
There is a large multipolygon with a source of "CanVec 6.0 - NRCan" that should
probably extend to the border. However I'm not sure. I'm wondering if anyone in
Canada could investigate. The area is defined as natural=wood.
BTW - I'm using USDA National Forest Services Topo Maps to add in rivers,
streams, etc. I see streams coming into the US from BC, but we don't have any
corresponding stream in Washington.
Clifford
I have promised to cut down on my swearing and drinking, which I have.
Unfortunately, this has left me dim-witted and nearly speechless. Adapted from
The Lion by Nelson DeMille
-or-
If you can't explain it simply, you don't understand it well enough. Albert
Einstein
_______________________________________________
Talk-ca mailing list
[email protected]
http://lists.openstreetmap.org/listinfo/talk-ca
