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--- Begin Message ---Hi Frank, Bravo - two quarters of a double horizontal dial! Regards, John--------------------------- Dr J Davis Flowton Dials http://www.flowton-dials.co.uk/ BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/ On Thursday, 3 January 2019, 12:49:00 GMT, Frank King <f...@cl.cam.ac.uk> wrote: Dear All, I have a simple rule with my puzzles: wait for a reply from Geoff Thurston and then reveal all. The time has come! In the recent spate of messages, both Bill Gottesman and Steve Lelievre were very close. Bill is the only person to suggest an azimuthal dial with vertical styles (which describes my design) but Steve's drawing (despite the polar styles) is remarkably close to my design too. The 'unusual space' is "The End-Flap of a Book" - not easy to guess! By arranging for the top and bottom edges of the front cover to serve as vertical gnomons, you can mark out an azimuthal dial on the end-flap. This way the user doesn't need to supply a gnomon, nor is there any need for any kind of pop-out gnomon. The sundial is shown in operation outdoors in the real sun at: http://www.cl.cam.ac.uk/users/fhk1/Sundials/GnomonGapDial.jpg This shows what the design looks like. There are many forms of azimuthal dial but, as one who enjoys astrolabes, I like stereographic projections. [OK, I do realise that my design uses the zenith as the centre of the projection and not the NCP!] In terms of 'looking good', this design hardly competes with the Nuremburg or Harvard dials or the dials in the stunning images that Sara has just sent us. We can all look forward to the Adler catalogue. Sadly, those dials look a bit expensive. The link above shows the upmarket version of my design and this costs 15 GBP but you do get a book bundled in at no extra charge! There are lots of pretty pictures of sundials inside. What about implementing the design for less than a dime? Well, a dime is about what it costs me to print out a sheet of paper, and all you have to do is to print out the following: http://www.cl.cam.ac.uk/users/fhk1/Sundials/DoubleGapDial.jpg This is intended for A4-paper. You may have to trim the edges if you use LETTER size. This shows what is hidden on the inside back cover of the book. That is where the early morning and late evening summer-time hours are found. All you have to do is to fold along the black straight line (a valley fold not a ridge fold), place the S-part flat on a horizontal table, and point the S to SOUTH [some users find this a bit surprising!]. You must arrange for the larger part to be perpendicular to the S-part. In summer, in the early morning and late afternoon, you have to place the larger part flat on the table; the edges of the S-part then serve as gnomons. This really is a working diptych sundial and they don't come any cheaper! Sadly it is designed for my latitude +52d 12m but anyone who has read this far is likely to be well equipped to adapt the design for another latitude. Adventurous readers can add the appropriate wiggles to the hour lines to deal with longitude offset and EoT. Maybe it would be best to design two such dials (one on each side of the paper), with December to June hour lines on one side and June to December hour lines on the other. In the unlikely event that you might want the up-market version (with book attached) please contact: Hallam Kindersley <hallam.works...@gmail.com> Very best wishes Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
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