Subject: Re: [BoundaryPoint] Re: Fiat boundaries
Date: May 05, 2001 @ 02:54
Author: michael donner (michael donner <m@...>)
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>I suspect that in a lot of cases, the principle of the boundary lay-
>out is specified in a treaty (like "the 49 deg. line"), but the
>actual demarcation is left for after the conclusion of the treaty.
>Then the field work starts, and errors inevitably creep in. The
>border markers are put on their spots, and from that time they are
>considered to be standing right on the border. So I think Brendans
>guess that the lines between bdy. markers are great circles is
>basically correct. That is, of course, if the boundary treaty speakes
>of a line like a parallel or some other line normally perceived
>as "straight". Sometimes, a boundary between two markers is defined
>in a treaty as "following a river" or some other feature in the
>field. In that case, other rules apply, of course.
>
>In this respect, it is interesting to know that along the benl
>border, very well marked by those nice and tall border monuments,
>this also occurs. On some stretches, auxiliary border markers are
>used. Eef Berns has a nice photo report of one of these stretches
>(where a lot of moving sand dunes constantly made the border a lot
>less visible) at <http://home.wanadoo.nl/~eefberns/tussenpaaltjes%>
>http://home.wanadoo.nl/~eefberns/tussenpaaltjes%
>20bij%20putte.html .
>
>Peter S.
>
>--- In BoundaryPoint@y..., "Brendan Whyte" <brwhyte@h...> wrote:
>>
>>
>>
>> >From: "Jesper & Nicolette Nielsen" <jesniel@i...>
>> >Reply-To: BoundaryPoint@y...
>> >To: <BoundaryPoint@y...>
>> >Subject: [BoundaryPoint] Fiat boundaries
>> >Date: Tue, 1 May 2001 07:45:41 +0200
>> >
>> >Which international boundaries are 100% fiat, meaning 100%
>straight?
>> >
>> >On the map I see:
>> >
>> >Morocco-Western Sahara
>> >Algeria-Mauretania
>> >Western Sahara-Algeria
>> >Nigeria-Chad
>> >
>> >But perhaps there are minor irregularities I cannot see on my map,
>so who
>> >can confirm this?
>> >
>>
>> Define 'straight'. Especially on a sphere. The only stright line on
>a sphere
>> occurs on a great circle. A line following any parallel apart fomr
>the
>> equator (the only great circle of latitude) is not straight, it
>bends left
>> or right. Therefore the US Canada boundary along the 49th is NOT a
>straight
>> line.
>> therefore the N-S segments of Mor-West sahara, the small WS-Alg and
>parts of
>> Niger-Chad probably are.
>> Second, although defined in treaties as following given parallels
>or
>> latitudes, or 'stright lines' joining certian points on diagonals
>(eg
>> Algeria's boundaries... are they great circles, or not?), most
>boundaries on
>> the ground are straight lines joining pillars erected where the
>paralleles
>> etc are thought at the time to be.
>> The US-Canada boundary was so defined, a series of line segments
>joining
>> pillars. Even if the pillars ARE on the 49th, the 'stright lines'
>joining
>> them will not be except at those pillars. So at leats once,
>intermediate
>> pillars were erected to make shorter line segments, and keep the
>boundary as
>> close as practical to the pilars.
>>
>> I am guessing that a straight line of sight fomr a pillar to
>another IS a
>> great circle segment.
>>
>> BW
>>
>>
>>
>>
>>
>> >Jesper
>> >
>>
>>
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