happily several more insertions too
--- In
BoundaryPoint@yahoogroups.com, "Lowell G. McManus"
<mcmanus71496@m...> wrote:
> See my several insertions below, the last one being the long
one.
>
> Lowell G. McManus
> Leesville, Louisiana, USA
>
>
> ----- Original Message -----
> From: "aletheiak" <aletheiak@y...>
> To: <BoundaryPoint@yahoogroups.com>
>
> > yikes
> > what makes yall think we are lost
> > in anything
>
> Forgive me. When I wrote "lost in all these maths," I didn't
mean "lost" in the
> sense of unable to find your way, but rather "lost" in the sense
of "lost in
> love" or "lost in bliss." Clearly, you derive more bliss than most
from being
> engrossed in complex maths. To each his own.
thanx pal
& i cant forgive you because i never faulted you
but only wondered why you thought that
& btw the bliss comes from being engrossed in the try
as i think you probably also appreciate
while the maths are just one means of advancing it
they could have been a map or canoe or shoes or whatever
in fact i usually have to struggle to invent the maths as i go
just like adapting everything else to the try
& would prefer it if there were an easier or better way
> > but anyway
> > please bust anything you know is lost or wrong
> > directly
> >
> > no need to strut or pussyfoot around first
> > whichever it is
>
> It is neither.
oops
bad joke by me then
seeing as you were already to the max with ivan
> > we are seeking the best available truth here on principle
> >
> > & if you can indeed advance our try for true bcidwa
> > or can even just tell us how we can
> > or can tell us how anyone can
>
> What I can do is tell you "how someone can"--that someone
being a surveyor.
>
> > why are yall standing on the ceremony of waiting for a
request
> > yikes
>
> It was already late at night, and I was trying in vain to find local
lodgings
> for New Orleans friends fleeing the hurricane. I also didn't
want to waste my
> time explaining something that you might already know, only to
learn later that
> you were as interested in the theoretical maths as in practical
measurement on
> the landscape.
>
> > also
> > or perhaps first
> > we already know there is a difference between what pros can
do
> > & what we ourselves have so far been able to do
>
> True. I disclaim being a professional surveyor, but I did take a
one-semester
> civil engineering course in land surveying as an elective in
1974. I have dug
> out my textbook (copyright 1969) from that course and reviewed
what I will
> explain below. Obviously, the instruments from that era were
not the lasers of
> today, but the principals are the same. It is interesting that this
task is all
> measurement without any complex maths involved.
>
> > but what do you mean by sufficient
>
> I mean equal to the usual standards of land surveying.
>
> Now, here's the explanation:
>
> If you will look at the topo map at http://tinyurl.com/6339v , you
will see that
> CAUS boundary monument 195 is approximately 900 feet east
of BCIDWA. The 195
> monument is a bit less than 120 feet higher in elevation than
the tripoint,
> being out of sight just over the top of a ridge. (The contour
interval is 40
> feet on the US portion of this map.) If you will pan west one
iteration, you
> will see that CAUS monument 194 is 663 feet higher than 195,
on a much higher
> ridge approximately two miles west. Of course, the CAUS
monuments are
> intervisible, and the boundary is defined as the line of sight
between them.
> The trouble is that 195, at least, is not visible from the tripoint.
>
> For those who don't know, the instrument called a transit is a
telescope (with
> crosshairs) mounted such that it can be rotated on axes in two
planes: around in
> the horizontal plane and end-over-end in the vertical plane.
The transit is
> mounted on a precisely levelable base that sets atop a tripod.
A plumb line
> hangs from the center of the instrument between the tripod
legs. The most
> precise transits are called "theodolites." The textbook says
that the best
> ones, reading to .1 second, could theoretically measure the
angle between two
> points an inch apart at a distance of 40 miles. There are
probably modern laser
> devices that do the same. Note that in our current problem, we
are not
> measuring any angles at all, but merely using the leveled
transit for sighting.
>
> The ideal situation here would be for the surveyor to set up and
precisely level
> his transit directly over CAUS 195. (If the monument is too tall
for this, he
> would use the process described in the next paragraph.) He
would sight monument
> 194 on the very high ridge to the west. Next, he would rotate
the telescope
> down to the near ridge just west of 195 and direct his rod man
to establish a
> point on CAUS atop this ridge. He would move the transit to
this new point,
> backsight to 195, flip the telescope to 194 for an accurcy check,
then rotate it
> downward to sight the tripoint down the hill. The rod man
would be directed to
> the point there that is on CAUS some slight distance north (we
assume) of the
> existing IDWA cairn.
>
> If the transit cannot be set up over 195, the surveyor will use a
process called
> "balancing-in" to establish a point in-line between two known
points. The
> surveyor would set up his transit on a trial point in the
approximate middle of
> the clear-cut vista on the ridge between the tripoint and 195.
Ideally, he
> should have visibility of both. He would take sightings
backward and forward to
> 194 and 195 and move his trial point as required until he has
the transit
> precisely on the line. The fine adjustments are made in the
"shifting head"
> between the tripod and the transit. When the placement is
correct, he will
> rotate the telescope downward to the vicinity of the cairn and
have his rod man
> establish the tripoint as above.
>
> If monument 194 is visible from the tripoint, forward and
backward sightings
> could be taken from the tripoint for confirmation. If not, the line
could be
> continued westward until 194 is visible.
>
> This is my best understanding of what I read.
thank you very much
& the existence of this tech does indeed advance our try
because the fact that it could be done
whether we or anyone else actually ever do it or not
trumps the endeavor to compute &or winnow the tripoint position
from the coords & 1909 disk position alone
since doing it that way would have been a last resort or default
option that could only kick in if no better way actually existed
& it was indeed out of order to jump to this presumption so soon
as i suspected it might prove to be
since a better way evidently does exist as you have described it
but at least my earlier endeavor to guess or predict where idwa
would fall if it could be found by sight line or survey art continues
to hold steady at the previously stated values
& all we can do now is wait til a sight based try is made if ever
& marvel to watch it fall into our centisec target window
& to learn exactly how close our best guess actually came
which now ironically will be a function not of our mathematical
diligence any longer but mainly of how close the published ibc
coords in centisecs chanced to be to the truth
so thanx again & best wishes to yall too
> > In BoundaryPoint@yahoogroups.com, "Lowell G. McManus"
> > <mcmanus71496@m...> wrote:
> >
> > > I hope y'all realize that while you're lost in all these maths,
any
> > competent
> > > surveyor with a transit and a rod man could locate BCIDWA
> > with sufficient
> > > accuracy on the line-of-sight CAUS in less than a half-hour
> > from CAUS monument
> > > 195 (which is only about 900 feet away) even if neither
> > monuments 194 nor 195
> > > are visible from BCIDWA.
> > >
> > > I can explain how on request.
> > >
> > > Lowell G. McManus
> > > Leesville, Louisiana, USA