Hi Frank, At the Adler Planetarium, there is a portable universal equatorial brass sundial (T-19) with a propped equatorial plate whose edges cast a shadow on a horizontal surface below. It works in a similar manner to the Nuremberg diptych Maciej pointed out.
The same technique is used with some overhangs on polyhedral dials in the Adler, but these examples are for fixed latitudes. For instance, M-324, A-400, and M-322. Here is a link to some images. https://www.dropbox.com/sh/nb4abv7eb2uspb3/AACnDhwBf-L5QVcvaZrh3Deoa?dl=0 These sundials will all be pictured and described in the forthcoming volume of the Adler's sundial catalogue, which I have authored. The volume is in press! Cheers, Sara -----Original Message----- From: Frank King <[email protected]> Sent: Wednesday, January 02, 2019 3:42 AM To: Schechner, Sara <[email protected]>; [email protected] Cc: Frank King <[email protected]>; [email protected] Subject: Re: Gnomon Gap Puzzle Dear Maciej and Sara, Gosh. Those are really incredible dials. The Nested L-shapes of the chapter rings on the Jacques Le Marie dial are very cleverly set out. I wonder how big a market there was for this kind of dial! Maciej's description of a Nuremberg Diptych - The shadow was cast by the edges of the upper leaf of the dial - is quite close to what I have in mind. This would be fine in British Latitudes but as you move nearer to the equator you find yourself having to peer inside an ever-narrowing gap! Very best wishes Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
