Hi Alexei & all, Interesting, yes. If only because the dial doesn't work properly. At least, not always. Around the equinox, a sharp-edged shadow is cast on both sides of the strip, perpendicular to the strip's axis, and the hour marks are correct. Towards the solstices, the shadow boundary on one side gets oblique and fuzzy, whereas the edge on the other side shifts away from the correct position. The deviation is some 25 minutes at most. John Moir observed this in a model, made from a wide elastic strip, and reported the results in the Bulletin of the British Sundial Society, nr. 95.1.
See also www.fransmaes.nl/sundials, click "Sundials??" in the menu. Best regards, Frans Maes Alexei Pace wrote: > Do not forget the very interesting sundial by Piet Hein as well which > is based on the helix. > > > On Thu, May 14, 2009 at 8:26 PM, Frans W. Maes <f.w.m...@rug.nl> wrote: >> Hi Chiu, John & all, >> >> The sundial by Duixans (1984) reminds me of the well-known photo of a >> gentleman checking his watch against a spiral sundial in a rainy scene. >> Hopefully the attachment (26 kB) makes it to the List. >> >> The photo is from Heinz Schumacher, Sonnenuhren. According to the caption, >> it was designed by J. Masuet and installed in Alpicat (prov. Lérida), Spain, >> in 1974. >> >> Best regards, >> Frans Maes >> >> >> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
