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Re: Stereographic Devices
From: Wolfgang Köberer
Date: 2010 Apr 14, 20:31 +0200
From: Wolfgang Köberer
Date: 2010 Apr 14, 20:31 +0200
Robin Stuart wrote:
"Bowditch (2002 Edition) page 31 states: The
principal navigational use of the stereographic projection is for charts of the
polar regions and devices for mechanical or graphical solution of the
navigational triangle.
END QUOTE
The devices mentioned would presumably exploit the property of sterographic projection that circles on the sphere remain circles on a planar chart. Does anyone know of examples of such devices?"
The
Zeiss ARG-1 and ARG-2 for instance. They have been discussed on the list before
(and a few of these have been sold on e-bay during the last few years) if I
remember right - so try the archive.
Stereographic projections have been proposed for the solution of the
navigational triangle several times in the last century: by Kohlschütter
(Meßkarte zur Auflösung sphärischer Dreiecke") or Favé (see Bowdich, 1977 Vol.
I, p. 608). Bowditch lists some more. Cotter deals with graphical solutions
briefly in his "History of nautical astronomy", p. 334ff.
Wolfgang
