Further, I want to know if those clocks, of Prague and Bern, can show when an eclipse occurs.
---------- Forwarded message ---------- From: Marcelo <mmanil...@gmail.com> Date: 2011/3/22 Subject: Re: Prague Clock To: Willy Leenders <willy.leend...@pandora.be> How is that lunar dial? Does it show the moon's phases and in what sign it is? And I'm intrigued by that zodiac, why are the winter signs (Sagittarius, Capricorn, Aquarius) narrower than the summer signs, Gemini and Cancer? 2011/3/22 Willy Leenders <willy.leend...@pandora.be> > More than the clock in Prague the clock in Bern has a calendar dial built > in and an indication of the day of the week. > The calendar in Prague is located separately under the clock. > > See > http://upload.wikimedia.org/wikipedia/commons/5/5e/Zytglogge_astronomical_clock_with_labels.png > > Willy Leenders > Hasselt in Flanders (Belgium) > > Visit my website about the sundials in the province of Limburg (Flanders) > with a section 'worth knowing about sundials' (mostly in Dutch): > http://www.wijzerweb.be > > > > > > > > Op 22-mrt-2011, om 11:26 heeft Willy Leenders het volgende geschreven: > > Jan, > > A better photo of the clock in Bern is at > http://www.photographersdirect.com/buyers/stockphoto.asp?imageid=1511348 > > This clock has at first sight a similar design as the clock in Prague. > However, it has not a outer ring that moves to and fro to indicate Italian > or Bohemian hours. > An indication of sidereal time is also missing. > > Willy Leenders > Hasselt in Flanders (Belgium) > > Visit my website about the sundials in the province of Limburg (Flanders) > with a section 'worth knowing about sundials' (mostly in Dutch): > http://www.wijzerweb.be > > > > > > > > Op 22-mrt-2011, om 01:02 heeft Jan Bielawski het volgende geschreven: > > Is the Prague clock of the same design as the one in Bern? See e.g. > http://starswebworx.lc-stars.com/swiss_photo/Bern.htm (scroll down a > bit). > > -- > Jan > > On Mon, Feb 28, 2011 at 09:15, James E. Morrison > <janus.astrol...@verizon.net> wrote: > > Perhaps some background would be useful to those on the list who are not > > familiar with astrolabes and astrolabe clocks. > > > The Prague clock is based on an astrolabe with the projection origin at the > > north celestial pole. This orientation causes the horizon arc to arc in > the > > reverse direction from a normal astrolabe, but it gives a more intuitive > > representation of the Sun's position. > > > The clock has three moving parts. A hand with a Sun figure rotates once in > > a mean solar day and the Sun's longitude is indicated by the position of > the > > Sun figure on the ecliptic (which is divided by the zodiac). The astrolabe > > rete, which has only the projection of the ecliptic on the clock, rotates > > once in a sidereal day. The difference in the rate of the two components > > keeps the Sun figure on the (approximately) correct position on the > > ecliptic. The third hand shows the position and phase of the Moon. > > > The Prague clock, and all other devices based on the astrolabe, indicates > > apparent time with the Sun hand. The only adjustment needed for it to > > indicate approximate civil time would be to simply move the Sun hand to a > > time. No changes in gearing are needed. But the Sun's position in the > > ecliptic (zodiac) would no longer be correct and any events (sunrise/set, > > culmination, etc.) would no longer be valid. That is, the Sun figure no > > longer represents the real Sun, > > > It could be made to show apparent time again by simply moving the Sun hand. > > > Best regards, > > > Jim > > James E. Morrison > > janus.astrol...@verizon.net > > Astrolabe web site at http://astrolabes.org > > --------------------------------------------------- > > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > >
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