Subject: Re: great roundup of circle boundaries in the united states
Date: Oct 09, 2000 @ 19:15
Author: Brian Butler ("Brian Butler" <bjbutler@...>)
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--- In BoundaryPoint@egroups.com, michael donner <m@d...> wrote:
> dear jerry
> welcome & thanxx for these several excellent additions
>
> of course you are right & i am happy to comply
>
> i only meant circle boundaries that are great
> not boundaries that are great circles
>
> great circles have always eluded me anyway
> so it is good that you have helped me out here
>
> like
> people seem to call things great circles that i would only be
inclined to
> call arcs of great circles
> etc
> etc
>
> i guess what you are implying also is that all true northsouth
boundaries
> are great circle boundaries too
> but true eastwest ones are not great circle boundaries
> or have i still not understood
>
>
>
> very glad to have your fragmentary tidbits too
> so please keep them coming
>
> i agree available tech of the day did make it moot
> as the great disparities among the various offsets indicate
> but it is always best to have the truth
> & it was interesting besides
>
> m
>
>
> >
> >I wish you would come up with alternative nomenclature for circular
> >boundaries since the term "great circle" has particular meaning in
> >the navigational, mapping and 'global'ly viewed world.
> >
> >A great circle being roughly described as the line between points
> >lying on the intersection of a plane which passes through the earth
> >center and each end point and the earth surface. We see these
> >things as straight lines and the shortest path between two points.
> >
> >There are boundaries which are straight, some which follow features
> >and some which are lines of constant bearing (loxodromes) of which
> >the east west near parallels of latitude are a mere subset. Anyway
> >examples of great circles are the easterly bounds of California, at
> >least by intent if not in fact, the south line of california also
is
> >a
> >straight line.
> >
> >Commenting on your #5
> >
> >--- In BoundaryPoint@egroups.com, michael donner <m@d...> wrote:
> >>
> >> 5
> >> washington dc
> >> u s naval observatory reserve
> >> circa 1830
> >> radius about 2100 feet
> >> <http://www.topozone.com/map.asp?lat=38.9219=-77.0608=25=s>
> >>http://www.topozone.com/map.asp?lat=38.9219&lon=-
77.0608&s=25&size=s
> >>
> >> another tangent
> >> this observatory is the american counterpart of the one in
greenwich
> >> england for setting time standards & it was used in the 19th
> >> century as a longitude standard as well in fact it was the
position
> >> of this observatory a few minutes west of the 77th meridian that
> >> caused many of the longitudinal state lines in the west
> >> such as those of wyoming & colorado to be similarly offset from
> >> integral meridians because boundaries used to be routinely
> >> described & marked in terms of whole degrees west of the naval
> >> observatory or of the washington meridian as it was also called
> >
> >
> >I think you will find that the current location of the naval
> >observatory (also the vice presidents home) at observatory circle
is
> >NOT now where it was when the washington meridian was often
> >referenced. That original location was somewhere down in 'foggy
> >bottom' south and possibly west of where the white house is found
> >today. The observatory was relocated to it's current location in
> >circa 1893.
> >
> > <http://www.usno.navy.mil/brief_history.shtml>
> >http://www.usno.navy.mil/brief_history.shtml
> >
> >I have not followed through to completion investigation as to what
> >degree the actual location is known, monumented or recoverable.
> >
> >Interestingly however there is an "axis" along a meridian very
nearly
> >on the washington meridian formed by the white house on the north,
> >and the jefferson memorial on the south and containing in order,
the
> >"zero mile stone", a monument whose name I cannot recall which lies
> >at
> >the center of the ellipse, and "the jefferson pier". There is a
> >new book just out about the attempts to establish the washington
> >meridian by Silvio Bedini, historian emeritus of the Smithsonian.
I
> >had previously found another interesting article with a different
> >slant on the issue:
> >
> ><http://www.usm.maine.edu/~maps/edney/vaughan.html>
> >http://www.usm.maine.edu/~maps/edney/vaughan.html
> >
> >I am not sure the official proposal for a meridian at the Jefferson
> >Pier was ever adopted or used. The description of the original
> >observatory as being "near the current location of the lincoln
> >memorial" which is a bit to the west, of this other axis indicates
to
> >me that the functional meridian based on the original naval
> >observatory was different than these later attempts to create
> >one at the Jefferson pier. And perhaps neither was effectively
used
> >due to the available technology of the day making it moot.
> >
> >Yes some state bounds refer to the washington meridian, but it is
> >not clear sometimes what was actually meant. Examples are that the
> >east line of CA was defined from greenwich but as I recall the west
> >line of Nevada was defined relative to washington meridian,
possibly
> >indicating an intent to consider the washington meridian at 77
degees
> >exact from greenwich but confusing the issue of it's definition and
> >use elsewhere. Often lines were defined one way in the territorial
> >boundaries and changed when statehood happened.
> >
> >Just some fragmentary tidbits... this is my first note on this
group.
> >
> >- jerry wahl
> >
> >>
> >> any other boundary circles anyone may be aware of anywhere would
> >make
> >> welcome additions
> >>
> >> m