You mean that along loxodromes the magnetic north is in exactly the
same direction, or do you mean true north? I thought it was true
north, actually, but I'm not sure now.
And do you know whether a great circle is measured along the earths
surface being a perfect sphere? I remember vaguely there is also an
approximated "earth surface", not the actual one with mountains on
it, but rather one that takes into account the fact that the earth is
not a perfect sphere but more "pear-shaped". I can't think of the
name now though. (And I remember vaguely (lots of vague memories)
that there is an earths surface based on a level of equal gravity.
But that would have to take into account the different matter inside
the earth. This is probably beside the point here.)
Peter S.
--- In BoundaryPoint@y..., David Mark <dmark@g...> wrote:
>
> The CA-US border (Lake of the Woods to Point Robers) consists of a
number
> of "straight" segments between boundary markers, it is sometimes as
far as
> 1/4 mile north or south of the 49th parallel.
>
> I put "straight" in quotes because of the issue of what constitutes
a
> straight line on the earth's surface. The usual definition of the
> equivalent of a straight line is a great circle. But great circles
other
> than meridians and the equator have costantly changing bearings
(compass
> directions). Lines of constant compass bearing, known as
loxodromes, are
> not shortest paths unless they run north-south or are along the
equator.
>
> David
>
> On Thu, 3 May 2001, michael donner wrote:
>
> > actually brian has filed the ultimate dissertation on this topic
> > but it would take a search or a chase goose to get us back to it
> >
> > i think one basic point of his tho was that the lines between
each pair of
> > monuments are unique great circles
> > & thus actually none of them ever aligns perfectly with any other
> >
> > & this is apart from the slight local irregularities that
necessarily occur
> > everywhere a monument is placed
> >
> > whether there are more egregious zigzags or offsets than these i
dont know
> >
> > m
> >
> >
> > >
> > >Interesting about Iraq-Jordan.
> > >
> > >My newest atlas show a straight line, but expedia.com shows a
zig zag.
> > >
> > >Is the caus border between Point Roberts and Lake Wood 100%
straight, or
> > >are the local irregularities?
> > >
> > >Jesper
> > >----- Original Message -----
> > >From: "michael donner" <m@...>
> > >To: <BoundaryPoint@y...>
> > >Sent: Thursday, May 03, 2001 12:38 AM
> > >Subject: Re: [BoundaryPoint] Re: Fiat boundaries
> > >
> > >
> > >> peter mentioned
> > >>
> > >> >
> > >> >--- In BoundaryPoint@y..., michael donner <m@d...> wrote:
> > >> >> & jesper
> > >> >> of these 5 or 3 singular fiat boundaries we have found
> > >> >> your chad nigeria line is probably the truest & purest in
the world
> > >> >> by virtue of being totally wet as well as probably unmarked
> > >> >> & therefore almost certainly absolutely undeflected by so
much as a
> > >> >single
> > >> >> subatomic particle
> > >> >>
> > >> >> m
> > >> >
> > >> >Not deflected, but Lake Chad being a very salty one with
fluctuating
> > >> >amounts of water (+salt) in it, there are possibly (also
fluctuating)
> > >> >amounts of land that are cut by the boundary.
> > >>
> > >> actually it is now a completely dry line
> > >> as recent photos clearly show in
> > >>
<http://www.afrol.com/Categories/Environment/env062_lake_chad.htm>
> > >>http://www.afrol.com/Categories/Environment/env062_lake_chad.htm
> > >> if you can mentally supply where the border is
> > >>
> > >> still being legal but indefinite it remains the most
pristine of all the
> > >> singular fiats
> > >>
> > >>
> > >> btw i also just noticed that the iraq jordan boundary
> > >> 1 of the 2 other best claimants of singular fiathood
> > >> has recently lapsed into a rather messy de facto zigzag
> > >> vaguely suggestive of the egypt sudan administrative line
> > >>
> > >> so it may well have bitten the dust for any playful purposes
> > >> & we could now be looking at a world class set with only 2
members
> > >> both dry
> > >> one marked
> > >>
> > >> >>
> > >> >> still cresting on my brendan waves
> > >> >> & so wishing for the perfect moment point of happy landing
> > >> >>
> > >> >
> > >> >Yes I know what you mean. The viscosity of these waves is
huge, I
> > >> >think. What substance is this? No salt water...
> > >>
> > >> i think it must be aurora australis concentrate
> > >>
> > >> responds shimmeringly to your every thought
> > >>
> > >> still dancing across the empyrian on it here too
> > >>
> > >> excelsior
> > >> m
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
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http://docs.yahoo.com/info/terms/
> > >>
> > >>
> > >>
> > >
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