Dear Frank, I recall that I saw once a nuremberg diptych of quite similar design - but without a string gnomon, which could have been even closer to Your idea. The shadow was cast by the edges of the upper leaf of the dial, tilted to the proper latitude with the help of foldable latitude arm.
I browsed my archives, unfortunately I was unable to find the image. It was a truly ingenous design ! Regards, Maciej Lose Od: "Frank King" <f...@cl.cam.ac.uk> Do: ml...@interia.pl; john.f...@keme.co.uk; steve.lelievre.can...@gmail.com; Wysłane: 16:41 Wtorek 2019-01-01 Temat: Re: Gnomon Gap Puzzle > Dear Maciej, John and Steve > > Congratulations on coming up with several > ideas. I should have asked your advice > several months ago! > > Although your ideas seem wildly different, > they all share elements of the actual design > which I shall reveal in due course. > > Maciej: I am most grateful to you for drawing > my attention to the Hans Troschel diptych dial. > I didn't know of this before and its design is > certainly (almost) confined by the noon gap. > This is getting very close to my thoughts. > > John: you ask... > > > Could you be designing a vertical dial for > > an interior south facing wall with a 'Velux' > > type window (or any rectangular glassed-in > > section) in the sloping ceiling above? > > This is less like my design but, although on > a different scale, it has features in common > with the Hans Troschel dial so it, too, is > on the right lines. > > > Alternatively could one use an unsupported > > sloping porch roof as an underslung gnomon... > > That would certainly work but I suspect there > would be a temptation to include markings > outside the gnomon gap. > > > But it would not be very weatherproof with > > no sides to the roof! > > Well, let's call it a sloping sun-shade such > as was once common on shop fronts in summer. > You could decorate the shop front with the > dial markings. In British latitudes the shade > would be very steeply sloping. The idea would > be fine in sub-tropical latitudes which have > more need of shade! > > Steve: I must study your arrangement in more > detail but, at first reading, you have a good > scheme which again shares elements of the > design I came up with! You will certainly > be surprised when you see the space that I > had to deal with :-) > > I might just add that my design can be > implemented for a total outlay of no more > than one US dime! Not all sundials are > mega-expensive!! > > More in due course! > > Frank > > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
