These astronomical clocks are part of a tradition of elaborate and complex clocks that showed all sorts of astronomical information. They are largely found in courtly collections put together in the 16th and 17th centuries. The inclusion of sundials on them was common in order to set the time of the clock.
A fine collection of clocks by Jost Burgi and others is found in Kassel: http://www.museum-kassel.de/index_navi.php?parent=1412 http://www.museum-kassel.de/sic2011/?parent=5108 And in Dresden: Mathematisch Physikalischer Salon http://www.skd.museum/de/museum-erleben/skd-mediathek/skd-videos/tuermchenuhr-mit-automatenwerk/index.html http://www.skd.museum/de/museen-institutionen/zwinger-mit-semperbau/mathematisch-physikalischer-salon/die-neue-dauerausstellung/index.html (not much is online but there are some great books) Sara Sara J. Schechner, Ph.D. David P. Wheatland Curator of the Collection of Historical Scientific Instruments Department of the History of Science, Harvard University Science Center 251c, 1 Oxford Street, Cambridge, MA 02138 Tel: 617-496-9542 | Fax: 617-496-5932 | sche...@fas.harvard.edu http://www.fas.harvard.edu/~hsdept/chsi.html From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Bill Gottesman Sent: Friday, April 26, 2013 9:19 AM To: Robert Terwilliger Cc: Sundials List Subject: Re: Alt Augsburg revisited I will start a guess. I think the Hour hand below the gnomon was to be set manually by the user to align with the shadow line from the gnomon. This hand was mechanically linked to the central clock dial minute hand, to show minutes past the hour. In this manner, a user would use the sundial to get a close estimate of the exact time, told by an hour hand and a minute hand. There exist other less complicated examples of German dials using a minute hand mechanically linked to some kind of moveable shadow indicator. The other clock dials seem to show day-of-week and day of month, and maybe a lunar calendar as well. Maybe there is an equation of time mechanism as part of the calendar, but I can not tell. How these would function, I have no idea, but I can't imagine that they were mechanically linked to the sundial. -Bill On Fri, Apr 26, 2013 at 8:37 AM, Robert Terwilliger <b...@twigsdigs.com<mailto:b...@twigsdigs.com>> wrote: I find it curious that nobody chose to respond to, or comment on, the instruments illustrated in the book Kunstuhrmacher in Alt Augsburg I put images online at: http://www.twigsdigs.com/sundials/kunstuhrmacher/kunstuhrmacher.htm These instruments had to be expensive, and since there seem to be a few surviving, somebody must have purchased and used them. I have a l lot of questions. How were these instruments used? Were they to be used in sunlight? If not, what was the gnomon for? How and why did the single hand indicate the hours from VI to VI? What happened at night? Two of them have the sundial-style line and curves to indicate declination/astrological sign. How did this work? Is it possible that these instruments were so early that the makers gave them the appearance of sundials to give the impression of accuracy to users who previously knew only sundials as time keepers? The first instrument illustrated is the only horizontal one and it appears to have been photographed from the north. It also has a dial (the left one) divided into eight segments with engraved illustrations and Latin text I wonder what that's about Until seeing these photographs I didn't know such things existed. Bob --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
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