Dear Frank, we should recognized that sundials were found from Hellenistic and Roman times with polar-oriented gnomons. But as the sundials then were usually made for unequal hours there was no need to use a polar-oriented gnomon.Maybe there was found one dial with equal hours: if you look on the winter side of the sundial of Oropos (you may get my article under The Arachne of the Amphiareion and the Origin of Gnomonics in Greece, in: Journal for the History of Astronomy 35 (2004), S. 435-445 ) you see that the winter circle is not divided in 12 parts as it should be for unequal hours. There is a picture of the Brunswick dial in my article "Vertical dials of the 5th -15th century" in BSS Bulletin No. 96.3, October 1996. Best wishes Karlheinz. -----Ursprüngliche Mitteilung----- Von: Frank King <[EMAIL PROTECTED]> An: [EMAIL PROTECTED] Cc: Sundial <[EMAIL PROTECTED]> Verschickt: Fr., 22. Aug. 2008, 11:49 Thema: Re: equal and unequal hours Dear Frans, You ask a very perceptive question: > > No doubt the transition to equal hours (whether > starting at noon, midnight, sunrise or sunset) > was gr dual but I feel it long predates mechanical > clocks. > Do you have any evidence supporting your feeling? No! I had heard (from you and others) that the olar-oriented gnomon was a much later development han one might guess, sometime around or after 1400 s you say. Also... I knew there were mechanical clocks at that time but had frogotten that clocks had been=2 0around for a entury or so by then. You are almost suggesting (perhaps you are actually uggesting) that the development of the polar-oriented nomon was a consequence of the development of echanical clocks. A polar-oriented gnomon is not, of course, essential or indicating equal hours. Indeed, Italian Hours re (almost) equal hours but you do not indicate talian Hours with a polar-oriented gnomon. My thought (my feeling!) was that Gianni or someone lse could suggest that sundials showing Italian Hours ere around before clocks. His answer is clear: > The equal hours started to be used after the advent of the tower clocks... This suggests that the advent of tower clocks was eminal to the popular use of equal hours and, I ssume, this applies to ANY kind of equal hours ystem, whether the day started at sunset, sunrise, oon or midnight. Given the late development of the polar-oriented nomon I had assumed that equal hours sundials tarting at noon or midnight were around before he introduction of the polar- riented gnomon. s this a false assumption? You say: > It has been suggested that the pole-style dial (and hence equal hours)... I wonder about the use of the word "hence"? You don't need a polar-oriented gnomon to ndicate equal hours (starting at noon or idnight) although it certainly helps. I am in danger of going wildly astray! Maybe ou could confirm (or refute) the suggestion hat there were sundials that showed equal ours starting at noon or midnight before he advent of the polar-oriented gnonom? I promise not to challenge your answer :-) Best wishes Frank --------------------------------------------------- ttps://lists.uni-koeln.de/mailman/listinfo/sundial AOL eMail auf Ihrem Handy!Ab sofort können Sie auch unterwegs Ihre AOL email abrufen. Registrieren Sie sich jetzt kostenlos. ________________________________________________________________________ AOL eMail auf Ihrem Handy! Ab sofort können Sie auch unterwegs Ihre AOL email abrufen. Registrieren Sie sich jetzt kostenlos.
--------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
