Hi Michael,
I've been hoping that Fred Sawyer would respond to your enquiry. At
last year's NASS Conference, Fred gave a talk on Rectilinear Altitude
Dials. It was, as always, a tour de force...and way over my head! But
in it Fred demonstrated the unity of Capuchin, Regiomantanus, Peter
Apian, etc. etc. plus his own earlier Nomographic Dial...as well as
novel dials based on the same principles.
best wishes,
Peter
On 11/05/2017 01:46, Michael Ossipoff wrote:
Sure, analytic geometry verifies that the Universal Capuchin dial
agrees with the formula that relates time, altitude, declination and
latitude.
But that isn't how medieval astronomers &/or dialists arrived at the
construction of the Capuchin dials.
Michael Ossipoff
On Tue, May 9, 2017 at 4:13 PM, Michael Ossipoff
<email9648...@gmail.com <mailto:email9648...@gmail.com>> wrote:
Thank you--Yes that's the article that I quoted, and from which I
got the diagram that I posted here.
That's the article that doesn't really explain anything.
It shows a picture of a Capuchin dial (figure 1), and also a
diagram of an orthographic projection of the celestial sphere
(figure 2). Its explanation basically consists of saying that
figure 2 looks like figure 1.
But, for one thing, of course it doesn't.
For one thing,
1. In figure 2, the parallel lines are parallel to the horizon. In
figure 1, the parallel lines in the bottom half-circle are
perpendicular to the direction of the sun.
2. In figure 2, the small circle to the left is centered within
the sun's extreme diurnal positive and negative altitudes, at the
depicted solar declination.
...but, in figure 1, it's the circle with the parallel lines is
just centered at the middle of the page.
3. In figure 2, the sun is shown at a southern declination,
something that is seemingly in disagreement with figure 1.
But all that is aside from the fact that the article just doesn't
give an explanation, other than its handwaving reference to the
alleged similarity of figure 1 and figure 2.
Anyway, yes, that's the article to which I was referring. So my
question is, "What would be a genuine explanation and
justification for the construction of the Capuchin and Universal
Capuchin dials?
Michael Ossipoff
2017-05-09 15:49 GMT-04:00 Putowsky via sundial
<sundial@uni-koeln.de <mailto:sundial@uni-koeln.de>>:
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---------- Forwarded message ----------
From: Putowsky <putow...@yahoo.com <mailto:putow...@yahoo.com>>
To: Michael Ossipoff <email9648...@gmail.com
<mailto:email9648...@gmail.com>>
Cc: sundial list <sundial@uni-koeln.de
<mailto:sundial@uni-koeln.de>>
Bcc:
Date: Tue, 9 May 2017 21:49:58 +0200
Subject: Re: Construction-Principle of Capuchin & Universal
Capuchin Dials???
Here is the complete article.
http://articles.adsabs.harvard.edu//full/1961JRASC..55...49S/0000054.000.html
<http://articles.adsabs.harvard.edu//full/1961JRASC..55...49S/0000054.000.html>
putow...@yahoo.com <mailto:putow...@yahoo.com>
On May 9, 2017, at 8:50 PM, Michael Ossipoff
<email9648...@gmail.com <mailto:email9648...@gmail.com>> wrote:
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
<image.png>
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