hugh & lowell & anyone else who is still following the bouncing ball & eglysd tripoint try
i have just ordered up uconns copy of brownlie again
which usually takes a couple of weeks to arrive here on cream hill
so you may as well hold fire on that if you were looking for it too
& hugh i really do understand & appreciate your point here that
it is all in the numbers
& a very fine point it is
except
i would say
it is all only in the applicable numbers
rather than
in all the numbers
in general
as well as here in particular
paying attention to all the numbers wont necessarily get us as close to our goal as paying
attention only to all the numbers that actually apply or might actually apply to that goal
& luckily
unless & until we actually do find that there is an applicable datum here other than the
default to wgs84
i think we can safely drop or at least postpone the question of exactly which numbers
might actually be applicable
& i realize you were taking aim at my generalization rather than at the point i was taking
aim at in making that generalization
but as of now
the proposed methodology of extrapolating eglysd from the wgs84 longitude of the
southernmost egly marker does not necessarily require any generalization
nor necessarily any datum shift at all
happily
let alone a shift to an outlandish datum
& without any datum shift
of course the anticipated latitudinal displacement of eglysd from wgs84 remains zero
a bigger & better question to consider now i think
while we are waiting for fresh hope or inspiration from brownlie
may be
how are we ever going to learn if anyone ever has laid a gps receiver of any kind on the
southernmost egly marker
to get a reading in any datum whatsoever
or
how are we ever going to find & get someone to go do so for the first time in history if
necessary
since this marker
if it can even be found
is itself already situated in rather remote & forbidding country
well fortunately we dont have to answer that just yet
but we will have to
or else invent a better way
or find that a better way already exists & awaits our discovery
--- In BoundaryPoint@yahoogroups.com, "Hugh Wallis" <hugh@o...> wrote:
>
> Boiling it down to actual numbers:
>
> Points defined using the datums typically used in Egypt are approximately
> 130m meridianally distant and 117m lattitudinally distant (resulting in a
> total straight line distance of sqrt(130^2 + 117^2) = 175m approx) from a
> point that has the same coordinates expressed as WGS84.
>
> Points defined using datums typically used in the Sudan are approximately
> 166m meridianally distant and 14m lattitudinally distant (resulting in a
> total straight line distance of sqrt(166^2 + 14^2) = 166m approx) from a
> point that has the same coordinates expressed as WGS84.
>
> So if an Egypt based datum was used then it is not clear to me that the
> lattitudinal difference would be "far" less than the meridianal difference
> (~117m vs ~130m)
>
> >>a general statement cant be made if you drag the exceedingly anomalous &
> inapplicable
> east indies into this african desert once again<<
>
> well sure - not just east indies but also USA and Canada (1927) and Eastern
> Europe - its all in the numbers really and that's just where they happen to
> differ differently :) - and that's the point I was trying to make really -
> just that it's "all in the numbers"
>
>
> _____
>
> From: BoundaryPoint@yahoogroups.com [mailto:BoundaryPoint@yahoogroups.com]
> On Behalf Of aletheiak
> Sent: Wednesday, January 11, 2006 1:05 PM
> To: BoundaryPoint@yahoogroups.com
> Subject: [BoundaryPoint] Re: but why suppose an eglysd datum has ever been
> stated or even can be synthesized
>
>
> thank you
> thank hugh
> huge thanxx & hugs
>
> & a few intertwingles follow
>
> --- In BoundaryPoint@yahoogroups.com, "Hugh Wallis" <hugh@o...> wrote:
> >
> > >>because the far greater component of any datum shift
> > displacement
> > both potentially & typically i believe
> > is in the longitude rather than the latitude
> > <<
> >
> > At http://www.colorado.edu/geography/gcraft/notes/datum/edlist.html
> (a.k.a.
> > http://tinyurl.com/8sexy - a fortunate coincidence - easy to remember at
> any
> > rate - hope it makes it through eveyone's spam filter) you can see the
> datum
> > shift from Local to WGS84 for many datums for long and lat in the dx and
> dy
> > columns (in metres). While the above assertion is true in some cases, if
> we
> > look at the datums that have typically been used for Egypt (European 1950
> > giving dx = -130 and dy = -117, Old Egyptian 1907 giving dx = -130 and dy
> =
> > 110), the lat and long displacements are not really "far greater" although
> > they are greater. If we look at those typically used for Sudan (Adindan
> > gving either dx = -166 and dy = -15 or dx = -161 and dy = -14) then they
> > are, however. Libya does not appear in the table.
> >
> > In some parts of the word the shift difference is the other way around -
> > e.g. Indonesia and much of South East Asia, some users of the European
> 1950
> > datum such as Spain and Portugal, and various remote islands, almost all
> > users of NAD27 i.e., Canada, USA, Central America, much of Eastern Europe
> > using S-42.
> >
> > It seems as though a general statement cannot be made therefore and that
> > every datum comparison needs to be done independently.
>
> you are right
> a general statement cant be made if you drag the exceedingly anomalous &
> inapplicable
> east indies into this african desert once again
>
> & at the same time you are right on again in having very much corrobrated
> for us the full
> extent of practically all the anomalies or variables that are actually
> applicable here
> for which i am exceedingly grateful
> & which does amply sustain my general statement & approach in this
> particular case
>
> so i should add to your excerpted swatch above
> & thanx to your attention
> if not far far greater
> as seems far likeliest
> then still unquestionably greater in any case
>
> & therefore
> we can now fully expect eglysd to be noticeably closer
> to the 22nd parallel than the eglys rock is to the 25th meridian
> in any known local datum including most particularly wgs84
>
> even if not absolutely necessarily much closer
> or very much closer
>
>
> & thats the point here
> specifically
> to get as close as possible to eglysd with what we actually do have to go by
> & where anything indonesian etc is almost definitely again a pure mirage
>
> unless you were trying to make a different point that i missed
>
> & one more insert below
>
> > On Brownlie - if anyone has access to a copy, some relevant references are
> > found at http://arabworld.nitle.org/texts.php?module_id=3
> > <http://arabworld.nitle.org/texts.php?module_id=3
> <http://arabworld.nitle.org/texts.php?module_id=3&reading_id=119&sequence=6>
> &reading_id=119&sequence=6>
> > &reading_id=119&sequence=6 (a.k.a. http://tinyurl.com/b89pu ) summarised
> > therin thus: "Libya's eastern borders result from agreements between Egypt
> > and Italy in 1925 and 1926, which superceded (sic) an earlier arrangement
> > between the Ottoman empire and Egypt in 1841, and from agreements in 1934
> > between Britain and Egypt (as the condiminium powers in Sudan) on the one
> > hand and Italy on the other. The latter agreement transferred the Sarra
> > triangle to Libya - the territory allocated to Sudan under the 1899
> > convention and lying to the south of the 22N parallel (Brownlie 1979;
> > 102-109, 133-140).". This secondary (or is it tertiary) source is quite
> > likely accurate, but, of course, may not be complete (which is what you
> are
> > hoping I guess).
>
> thank you
> this is again very much to the point
> & tho nothing new beyond what we have seen in ibs 10 & 18 & 61
> the fact that you promise 15 more pages gives reason to pursue this anyway
> along with the fact that it is a good decade or 2 more recent than the ibs
> studies
>
> end inserts
>
> >
> >
> > _____
> >
> > From: BoundaryPoint@yahoogroups.com [mailto:BoundaryPoint@yahoogroups.com]
> > On Behalf Of aletheia kallos
> > Sent: Wednesday, January 11, 2006 11:06 AM
> > To: boundaryPoint@yahoogroups.com
> > Subject: Re: [BoundaryPoint] Re: but why suppose an eglysd datum has ever
> > been stated or even can be synthesized
> >
> >
> > thanxx
> > i appreciate the question no less than the critical
> > review behind it
> > but first
> > with regard to the egsd signs
> > all indications thus far are that they date from the
> > militarily tense early to mid 1990s period
> > so their accuracy was very likely limited by selective
> > availability in any case
> >
> > & regarding egly
> > yes indeed i could & probably should ask this just to
> > rule it out with greater certainty
> > tho i have already given my reasons for doubting there
> > is a bilaterally official datum even there
> > in my previous post
> > to which i should now add that the elusiveness or
> > formlessness of all those so hopefully lovely egly
> > border arcs
> > which arent at all discernible as arcs on any maps i
> > have yet seen
> > is just one more indication of the crudeness & hence
> > datumlessness of the 1927 egly demarcation survey
> >
> > & yikes reason even to doubt that the commissioners
> > would have been proud enough of their handiwork in the
> > wilderness to even plat it out
> > or worry about it in any other way much beyond
> > degmindec or degmindodec
> > let alone degminsec etc
> >
> >
> > but in the meantime i also realized that tho my
> > proposed 487 mile extrapolation from the nearest egly
> > rock would nail the longitude of eglysd with as much
> > precision as that rock itself had already been nailed
> > with
> > it still wouldnt at all necessarily nail the latitude
> > of eglysd any better than we already have it
> >
> > 22nd parallel
> >
> > hahahahaha
> >
> > ahhh
> >
> >
> > nevertheless i believe this will prove to be a smaller
> > shortcoming than one might initially think
> > because the far greater component of any datum shift
> > displacement
> > both potentially & typically i believe
> > is in the longitude rather than the latitude
> > since latitude is first a sidereal fact while
> > longitude is only a terrestrial & far more subjective
> > one
> >
> > meaning all possible versions of the 22nd or any other
> > parallel will bunch up much closer together generally
> > than will all possible versions of the 25th or any
> > other meridian
> >
> >
> > for example the example i think we may have begun with
> >
> > azconmut shifting between nad27 & nad83
> > has 59 meter longitudinal displacement & only 2 meter
> > latitudinal
> > which btw per pythagoras means more than 99point94
> > percent of the distance of any shift there is
> > contributed by the longitudal portion of the shift
> > alone
> >
> > so our range of possible latitude values here at
> > eglysd should be a correspondingly small fraction of
> > the distance from the 25th meridian of the
> > southernmost egly rock
> > in whatever datum it is bagged & or expressed
> >
> > which means
> > using say pilotage gps on the southernmost egly rock
> > we would get the correct submeter wide ribbon of
> > longitude for eglysd in any datum
> > & but only the correct say meter or at most several
> > meter broad ribbon of latitude for it
> >
> > & thus using commercial gps any datum shift in the
> > latitude would most likely be imperceptible
> >
> >
> > & tho i thought of this saving grace shortly before
> > falling asleep last night
> > the confirmation of it came to me in a dream
> > from which i awoke laughing out loud
> >
> > in the dream i had just reached eglysd by car & found
> > a border guard there with his young son who was
> > operating a walkie talkie
> >
> > of course the guard asked me to open my trunk
> > which i did
> > & inside it
> > much to my surprise
> > was his other son
> > an identical twin for all i could tell
> > talking back to them on another walkie talkie
> >
> > hahahahaha
> >
> > & smiling & shaking my head in amazement ever since
> >
> > can you dig it
> >
> >
> > but anyway
> > where do i think we are now
> >
> > i think
> > we are beginning to think mohamed wont answer perhaps
> > because he doesnt know
> > & we are looking for brownlie just to check as much as
> > we can of our guesswork to date
> > as well as to get a better fix on any potential source
> > docs
> >
> > but actually
> > it just occurs to me too
> > since this southernmost egly rock
> > which we are trying to hang our hat on
> > is so beguilingly close to the 29x25 project
> > intersection point
> > why dont we just sponsor a fellowship for some
> > deserving confluencer to bag it for us
> >
> > --- "Lowell G. McManus" <lgm@w...> wrote:
> >
> > > While you're corresponding with them, couldn't you
> > > just ask if there is an
> > > official datum for the delimited but undemarcated
> > > portions of the EGLY boundary
> > > and what datum they used when erecting the
> > > (presumably) unilateral signs on
> > > EGSD? Wouldn't that beat trying to extrapolate from
> > > afar?
> > >
> > > Lowell G. McManus
> > > Leesville, Louisiana, USA
> > >
> > >
> > > ----- Original Message -----
> > > From: "aletheiak" <aletheiak@y...>
> > > To: <BoundaryPoint@yahoogroups.com>
> > > Sent: Tuesday, January 10, 2006 9:36 PM
> > > Subject: [BoundaryPoint] Re: but why suppose an
> > > eglysd datum has ever been
> > > stated or even can be synthesized
> > >
> > >
> > > > aha & far better
> > > > we just ask the egypt border force if it happens
> > > to have gps era survey data
> > > > on this
> > > > southernmost egly marker at any level of
> > > exactitude
> > > > & extrapolate eglysd from it
> > > > aha
> > > > of course
>
>
>
>
>
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