Michael,
Some years ago, I spent a lot of time to search a simple geometrical
justification of these kind of dial. The best way I found is:
- for the Capuchin: from the orthographic projection of the celestial
sphere on the local meridian (fig. 1)
- for the Universal Capuchin: from the orthographic projection on the
hour plane of the Sun (fig. 4)
These figures are detailed here:
http://cadrans-solaires.scg.ulaval.ca/v08-08-04/pdf/XIII-4-p10-4.pdf
and the links between the figures and the dial are briefly explained here:
http://gnomonique.fr/divers/anal_3_angc.pdf
Of course, it isn't quite simple but, perhaps, you will find some
interest in these articles.
Best regards
Yvon
Le 09/05/2017 20:50, [email protected] a écrit :
I'm not asking about the *instructions *for constructing Capuchin and
Universal Capuchin dials. I'm asking about the principle, the explanation,
the justification, for their construction.
Some websites have said or implied that it has to do with an orthographic
planisphere. I'm familiar with the use of a universal planisphere, an
azimuthal projection of the celestial sphere in equatorial-aspect. ...but
it isn't entirely clear how that relates to the Capuchin dials.
I found a handwaving explanation on the web. I've pasted its diagram, and
some of its "explanation", below in this e-mail.
The explanation says that the diagram below, an orthographic projection of
the celestial-sphere, looks just like a Capuchin dial. And that's supposed
to be an explanation.
So, how does an orthographic projection of the celestial-sphere lead to a
justification and explanation of the construction of a Capuchin or
Universal Capuchin dial?
Can anyone here explain that? If so, the explanation would be appreciated.
Michael Ossipoff
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