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Yes, it is clearly meant for a polar axis gnomon. The hour lines are symmetrical with 6 and 6 crossing at the root of the gnomon so it is meant to be directly south-facing. However the hour angle lines do not appear to be accurate for any latitude. Iif you measure the hour angles and try to calculate a latitude, the dial is not consistent. If the 11-12 hour angle is correct for 41.4 degrees, then the 6-7 hour angle is too small. If the 6-7 angles is correct for 53 degrees, then the 11-12 hour angle is too big. The errors are on the order of 2 or 3 degrees, which is a lot. It could possibly be "authentic" in the sense that it was designed and made when as claimed but it has the wrong kind of gnomon, and even if the gnomon were corrected it would tell time very badly no matter where it is placed. Jack From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On Behalf Of John Carmichael Sent: Monday, May 30, 2011 10:56 AM To: 'Sundial List' Cc: i...@mediadesign.me Subject: FW: sundial /Jacopo de'Benci Hi Jan- I'm forwarding your letter and my comments to the Sundial List. Perhaps the sundial experts in our group can help you more than I can! ----------------------------________________________________________________ _______________________________ Hello Dialists: I received this letter inquiring about an old European sundial. I'm not an expert on these things, so I'm forwarding the letter to you guys. I've never heard of the maker- Jacopo de' Benci whose name is inscribed on the dial. Looking at the enlarged photo of it at http://www.mediadesign.me/pollaiuolo/images/sonnenuhr-jacopo-de-benci-4.jpg you can see it has a perpendicular rod gnomon, implying that at first glance it is a nodus-based design. But the location of the rod seems to be incorrectly located at the convergence of the hour lines. I'm thinking that this dial was not designed to have a perpendicular gnomon. It should have an angled polar axis gnomon (an angled rod or a triangular sheet). Perhaps the rod was added to the original attachment hole after the original polar axis gnomon fell off at an earlier date. Does my analysis seem correct? Please copy your replies to Jan K. Botor at i...@mediadesign.me Thx John C.
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