Dear John, I know this object as “Horizontoscope". http://www.horizontoscop.com/eng/index_eng.html
I bought one recently after reading about it in one of Helmut Sonderegger’s articles, where he gives the math of it. https://www.herzog-forsttechnik.ch/wp-content/uploads/2022/08/Sonnenkompass_Flyer-2022.pdf It’s quite interesting how the hyperbolic surface makes the image independent of the height between the observing eye and the device. There is a german wikipedia entry. https://de.wikipedia.org/wiki/Horizontoskop Maybe someone from the sundial list can produce an english entry with the theory. It’s a nice device ! best regards Werner On 26 Oct 2022, at 02:45, John Pickard <john.pick...@bigpond.com<mailto:john.pick...@bigpond.com>> wrote: Good morning, Has anyone come across this dial-related device? https://picclick.co.uk/ARCHITECT-TOOL-Window-SUNLIGHT-SUN-ELEVATION-Enraf-144741549298.html Cheers, John. Dr John Pickard. --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
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