Hi Fabio This use of an analemma design on the analemmatic dial has been a confusing error that goes back at least to the early 20th century introduction of the curve on the dial in Brou, France. The use of a double analemma design with curves calculated to limit error to just a few minutes throughout the year goes back at least to 1970 and the work of Ken Seidelman at Longwood Gardens in Pennsylvania. For a detailed discussion with equations, etc. see my article "Of Analemmas, Mean Time and the Analemmatic Sundial" that you can download at https://dl.dropboxusercontent.com/u/4837615/scia7.pdf Brian Albinson has taken this idea to heart and, using a slightly different approach to the equations, has designed several such dials in the Vancouver area.
Fred Sawyer On Tue, Aug 16, 2016 at 12:23 PM, fabio.savian <fabio.sav...@nonvedolora.it> wrote: > > hi all, > > I draw inspiration from the image sent by Brian Albison for a meditation. > > I often found analemmatic sundials with the analemma. Has it a sense ? > > Standing on the analemma one can get the right correction for eot only at > noon. > Most of these sundials don't report a warning about it, so the users get a > wrong time al the day, except noon. > Moreover some of them haven't the calendar on the meridian line but only > on the analemma, so the misunderstanding is sure. > > The use of a table with the eot should solve the curiosity to get the mean > time, so I wonder why this kind of sundial is knowspreading with the > analemma while it is not suitable for this. > Do you where this use come from ? > > ciao Fabio > > Fabio Savian > > Inviato da Tablet Samsung. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -------- Messaggio originale -------- > Da: Brian Albinson <brianalbin...@shaw.ca> > Data: 16/08/2016 18:04 (GMT+02:00) > A: Sundial Group <sundial@uni-koeln.de> > Oggetto: Double analemma dials > > Hi folk > > We have built 3 direct reading mean time double analemma dials, > (including the Highlands School dial) in the Vancouver area and are > curious to know if any others exist in the world (apart from the > Longwood dial). > > Brian Albinson > > Len Berggren > > Vancouver, Canada > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > >
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