bum url hopefully corrected now in text below
apologies
it is an interesting question tho
no other inserts
--- In
BoundaryPoint@yahoogroups.com, aletheia kallos
<aletheiak@y...> wrote:
> well doc & dave &al
> i think i have finally done it
>
> extracted the ultimate computational truth out of
> bcidwa
> thanxxx also to you all
>
> but it is still in rather long winded format
> so please keep bearing with me
> & maybe you can help improve it too
>
>
> to begin with
> cribbing from the comparatively finer but sketchier
> table of geodetic constants at lower right in
>
http://www.convertit.com/Go/Convertit/Reference/AMS55.ASP?Re
s=150&Page=8
> i have computed the length of a minute of latitude at
> the 49th parallel as 1853meters plus 508mm
>
> & borrowing directly from the coarser but busier table
> in
> http://home.online.no/~sigurdhu/Grid_1deg.htm
> i have it as 1853meters plus 500mm
>
> so which is truer
> & how many digits are reliable in any case
>
> but no matter
> as these are only idle if still interesting questions
> since both produce fully significant centisecs of
> 1 point 01351feet
> & thats plenty significant
>
>
> also
> parenthetically
> & only for later use
> they produce fully significant millisecs of
> zero point 101351 foot
>
>
>
> but so anyway for starters
> this true centisec length in 6 significant digits
> rather than just a plain approximate statute foot is
> the true breadth of the swath cut by the ibc centisec
> coord ribbon between monuments 194 & 195
>
>
> a n d
>
> in
> http://groups.yahoo.com/group/BoundaryPoint/message/14910
>
> i was wrong to needlessly dumb down the plaque coords
> to the level of the ibc coords
>
> but by the same token i think it would also be rash to
> trust the millisecs expressed on the plaque as
> anything more than actual demicentisecs
> since their final significant digits are
> suspiciously
> 5 & 0 respectively
> & together present a 16 to 1 probability that they are
> not significant millisecs at all
> but only significant demicentisecs
>
>
> for these could easily prove to have been ambiguously
> &or overconfidently stated on the plaque in nad83
> & thus could have been overconfidently converted into
> nad27 by me
> with 1 full additional significant digit each
> as
> nlat 48d 59m 57s 357 & wlong 117d 01m 52s 848
> when the likelier value ranges 5 full millsecs
> between the 355th & 360th millisec actually
> of the 58th second of the final minute of the 49th
> degree of latitude
> in the case of the datum we will need to use here
>
>
> but by taking into account both the major & the minor
> probability & weighting them proportionally
> since neither can be dismissed out of hand
> & since their relative likelihoods can also be
> conveniently & precisely computed
> we can indeed now improve the accuracy of the
> placement of our intermonumental caus swath across the
> idwa meridian no less than we have improved the
> accuracy of the measurement of its width
>
>
> so
> recalculating the ratios in
> http://groups.yahoo.com/group/BoundaryPoint/message/14912
>
> to the limit of their actual applicability
> we find that the centisec swath as stated above in
> millifeet would be centered on the idwa meridian
> exactly 4 point 7379807692 centisecs south of the
> latitude of monument 195
> which is to say
> at precisely nlat 48d59m57s37262019231
> on a flat earth
>
> or comfortably down to the 373rd millisec anyway on
> the geoid
>
>
> & therefore
> the center of the truest or at least likeliest
> available bcidwa centisec swath of width 1 point 01351
> feet
> or 12 point 16212 inches
> lies between 13 & 18 millisecs north of the 1909 disk
> center
>
> or in better words
> between 1 point 317563 & 1 point 824318 feet north of
> it
>
> or in still easier words to understand
> between 15 point 810756 inches north of it
> & 21 point 891816 inches north of it
>
>
>
>
> therefore the better of the 2 best available guesses
> for true bcidwa is centered 18 point 851286 inches
> north of the 1909 disk center
> plus or minus 6 point 08106 inches
> & the caus centisec swath therefore most
> probabalistically crosses the idwa meridian between 12
> point 77022 & 24 point 93234 inches north of the 1909
> disk center
>
>
>
> if however we knew the plaque coords were true
> millisecs
> an eventuality which is actually a 16 to 1 long shot
> we could then confidently say the swath was centered
> more nearly exactly 15 millisecs north of the disk
> center rather than ranging so crudely 13 to 18
> millisecs north of it
>
> & in this event the truest available bcidwa would be
> centered 18 point 24318 inches north of it
> & thus midway between swath edges lying
> 12 point 16212 inches north of it
> & 24 point 32424 inches north of it
>
>
> so we can congratulate ourselves twice
>
> once for nailing the major & once for the minor
> premise
>
>
> & for a last hurrah
> combining both these premises into one
> we get a slightly expanded range
> extending a bit more than a full centisec now
> between 12 point 16212 inches north of it
> & 24 point 93234 inches north of it
>
> but as for the best guessed single point in that range
> most interestingly
> by weighting & hedging the probabilities at 16 to 1
> we get a las vegas betting line & final word at
> 18 point 81552 inches north of the 1909 disk center
>
>
> thanx for your patience
> & please add on or bust anything you can
>
>
>
>
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