--- Hugh Wallis <
hugh@...> wrote:
> Aha - here is the description of how confluence.org
> deal with confluences on
> borders
> (http://www.confluence.org/infoconf.php#owner). It
> appears that this
> doesn't add anything of use to our disucssion
true but please see below
to help clarify what our discussion actually was or is
about
> It is a shame that they didn't take a
> GPS reading at the
> border post (which is what they call it) to indicate
> whether it was located
> on the 22°N parallel according to WGS84 or was some
> minutes/metres distant
> from that line.
why a shame
> One thing I haven't yet detemined is how
> confluence.org decided which
> country to record confluences as being in when they
> are nominally on a
> border. In every case they have made such a decision
> rather than listing a
> confluence as being in more than one country or
> state (or equivalent),
> probably because their website organisation and
> database structure forced
> them to, but I would like to know for sure what
> their logic was.
why would you like that
> Following
> links from their site I did reach the following page
> -
>
http://www.colorado.edu/geography/gcraft/notes/datum/edlist.html
> - which is
> instructive since it lists the deviation from WGS84
> (which is the datum used
> by confluence.org) for most regions of the world.
instructive of or for what
> We can see from this that datums commonly used in
> Egypt and Sudan differ in
> their deviations from WGS84 by various amounts but
> typically in the order of
> 130 to 200 metres (sqrt(dx^2 + dy^2)) and Libya is
> not mentioned. So, unless
> the borders and tripoint are statutorially or by
> treaty defined as being on
> the 25°E meridian and 22°N parallel using WGS84 it
> is evident that the
> intrepid explorers who made it to 22°N, 25°E (WGS84)
> were in all probability
> a good distance from the actual tripoint.
would you add to your unless proviso here above as you
ultimately conceive here below
or unless they were & remain undefined
& thus default to wgs84
> It is also
> conceivable that we
> have a tripoint here that is not fully defined (as
> envisaged in the
> Indonesian paper) because of different datums
> possibly having been used (or
> not specified at all) in different treaties and the
> location not have been
> surveyed and agreed to in a tripartite agreement. It
> is conceivable that
> until and unless it is ever determined by one of the
> parties that it
> actually matters and the issue is renegotiated the
> situation might remain as
> indeterminate as those described in the Indonesian
> paper.
this strikes me as not just conceivable but likeliest
based on everything we have found as well as not found
up to this point
> All speculation of
> course but in the absence of any definitive evidence
> in favour of WGS84
> being the datum used by the three countries to
> determine the position of
> their borders I would vote (inasmuch as my vote
> actually means anything!)
> against calling this a class B find given that there
> seems to be plenty of
> evidence of "reasonable doubt".
your vote doesnt count because bp is not a democracy
but a proprietorship
here we vote as it were only with our feet & reasoning
& i agree class b is highly doubtful but not for the
same reason as you do
in my view it is doubtful in the first place because
of the 14 meters or more of gps fudge between the
subject & object of the try
as indicated by photo 1
i mean if it really had been an earnestly punctilious
multipointing try in the first place
> Obviously I would
> also be prepared to change
> my vote if such definitive evidence in favour of
> WGS84 surfaced.
& what if no evidence of datum or of demarcation ever
surfaced
as happens to be the case so far
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