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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There is always a great circle route between two points on a sphere
(the great circle is the intersection of the sphere and the plane
defined by the two points and the center of the sphere), so this
raises the question of what is meant when boundary lines connect two
monuments along a "straight" line. It should be the great circle
route? How it looks on the map depends on the map projection.

For example, the US/Canada boundary along the 49th parallel is not a
great circle route when defined that way, but it is actually made up
of numerous discrete segments, which probably are great circle
routes. The US should maybe insist on a great circle connecting the
Lake of the Woods and NW washington State, for simplification of the
boundary of course.

BJB

--- 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