--- Begin Forwarded Message ---
Date: Mon, 11 Feb 2002 10:19:00 -0600
From: Nat Case <[log in to unmask]>
Subject: Re: Geographical center of the continents <fwd>
Sender: Nat Case <[log in to unmask]>



The problem with all these calculations is they use different preset
notions of the continents' exact shapes. Are your base polygons based
on mean high tide? At what level of detail is the shoreline/coastline
drawn? Do you include long tidal estuarine rivers like the Hudson or
Thames? Generalization will probably tend to add land especially in
"porous" areas like deltas. Do you include inland seas?

And, of course, you run into tricky questions based on human
definitions of continents: Where EXACTLY does Asia end and Europe
begin? or North and South America?

Do you take into account the earth's curvature? Surely that would
affect balance. And if you do, what sphereoid/geoid do you assume?

There being no one reliable answer, I think the middle of the
continent is where they put up the obelisk that says it is.

Nat Case
Hedberg Maps, Inc
Minneapolis, MN (about four blocks from 45 degrees N!)


>Hi!
>
>I recently read a very entertaining book called "Tuva or Bust!" by
>Ralph Leighton.  It is about the late Nobel laureate Caltech
>professor Richard Feynman and his friend, Ralph Leighton.  In the
>1980s they tried for several years to get through the Soviet
>beureacracy to visit Kyzyl, the capital of Tuva (Respublika Tyva) in
>Russia.  An unnamed "traveler" had gone there in the 19th-century
>and erected a monument to the geographic center of Asia.  Wondering
>how this person might have determined Kyzl to be the center of Asia,
>Leighton copied maps of Asia of various projections, pasted them to
>cardboard and cut them out, finally balancing each on the head of a
>pin.  He determined that this 19th century traveller must have done
>just that:  a map from the 1850's in Gall's stereographic projection
>balanced perfectly!  I guess that's one way to do it!
>
>Feignman and Leighton then used a mathematical formula to pinpoint
>the center of Asia, and they came up with 45 deg. 31" N and 86 deg.
>59' E, "in the middle of some sand dunes in the Dzungarian
>Basin--about 115 miles north of Urue mchi...but more than 500 miles
>southwest of Kyzyl."
>
>That's my two cents worth.
>
>All the best,
>
>Geoffrey Forbes
>Director of Operations
>
>East View Cartographic, Inc.
>3020 Harbor Lane N
>Minneapolis, MN 55447-5137
>U.S.A.
>Tel (763)550-0961
>Fax (763)559-2931
>www.cartographic.com
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