Dear Frank, I love the solution that Maciej pointed out in the Troschel dial (MHS 70006) and want to add that I have seen on this also on polyhedral dials.
In addition, Harvard has a double-string-gnomon inclining dial by Jacques Le Maire (CHSI 7416) (http://waywiser.fas.harvard.edu/objects/12220/inclining-doublestringgnomon-sundial?ctx=c7b5cc99-4010-4ef5-a0ef-a842c4c635e4&idx=53) which is like the Troschel but portable for multiple latitudes. Happy New Year, Sara Sara J. Schechner Altazimuth Arts 42°36'N 71° 22'W West Newton, MA 02465 http://www.altazimutharts.com/ Sara J. Schechner, Ph.D. David P. Wheatland Curator of the Collection of Historical Scientific Instruments Lecturer on the History of Science Department of the History of Science, Harvard University Science Center 251c, 1 Oxford Street, Cambridge, MA 02138 Tel: 617-496-9542 | Fax: 617-495-3344 sche...@fas.harvard.edu |@SaraSchechner http://scholar.harvard.edu/saraschechner http://chsi.harvard.edu/ -----Original Message----- From: sundial <sundial-boun...@uni-koeln.de> On Behalf Of Frank King Sent: Tuesday, January 01, 2019 10:42 AM To: ml...@interia.pl; john.f...@keme.co.uk; steve.lelievre.can...@gmail.com Cc: sundial@uni-koeln.de Subject: 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 --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
