I have seen a photo of this dial type in one of the common dialling books (Waugh, Rohr, or Mayalls). The photo looked like it was from the 1960's. If I can get my hands on it I will be more specific.
Bill Gottesman Burlington, VT Message text written by "Günther Faltlhansl" > Hello Fellow-Dialists, I have been following your various exchanges of thoughts for not too long now and I must have missed somehow just what triggered the discussion on patents. They are not really in the center of my interests anyhow, but the discussion reminded me of a PCT (International Application published under the Patent Cooperation Treaty), published in 1990 by a Danish applicant, Piet HEIN. (Internat. Publication No: WO90/13854). "The invention comprises a strip-shaped body with surfaces substantially in the form of helicoidal surfaces. At least one of the helicoidal surfaces is graduated." This twisted metal band seems to be oriented parallel to the axis of the earth and one edge is casting its shadow onto the "inside" of the band. Unfortunately nothing is said how the graduation is carried out (empirically?) and there is no theory given. I have not found such a dial in any of my gnomonic literature (clearly it is any invention!). I would be interested in a mathematical theory behind it. Would anyone among you be possibly familiar with it? Regards, Günther Faltlhansl 48°09' N 16°52' E <
