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 >> <[email protected]> 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 >>> [email protected] >>> 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 >
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