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> 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>: > >> Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die >> eigentliche Nachricht steht dadurch in einem Anhang. >> >> This message was wrapped to be DMARC compliant. The actual message >> text is therefore in an attachment. >> >> ---------- Forwarded message ---------- >> From: Putowsky <putow...@yahoo.com> >> To: Michael Ossipoff <email9648...@gmail.com> >> Cc: sundial list <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 >> >> putow...@yahoo.com >> >> On May 9, 2017, at 8:50 PM, Michael Ossipoff <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> >> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> >
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