Hello Claude, Micknik developed the bifilar dial in the 1920's. 2 straight threads, parallel to an horizontal plane, were used as shadow casters. He named this dial a bifilar dial. Also in German the word is bifilar, however the pronunciation is some different. For historical reasons I think it is important to keep this name for this kind of a sundial.
In stead of 2 threads also 2 edges of planes may be used as shadow casters, but still I suggest to use the word bifilar dial. There is no fundamental change in the concept of the dial. In the 1970's and 1980's new dials appeared in which one of the threads or edges is no longer straight but has a curved shape to get other patterns for the lines on the sundial. To my opinion these dials still are bifilar dials because the principle isn't changed: the dial has to be read at the intersectionpoint of 2 shadows of 2 threads or edges. However, I realize that naming and classifying sundials is a difficult matter in gnomonics. Best wishes, Fer. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E ----- Original Message ----- From: Claude Hartman <[EMAIL PROTECTED]> To: sundial list <[email protected]> Sent: Friday, October 20, 2000 1:06 PM Subject: Bifilar Again! > Many of you may remember a thread on this list in March of this year > about the "bifilar" name. (I tried to look for it on the AstroArchive > site but I > could not do a search for titles or keywords. The egroup site is much > better: http://www.egroups.com/group/sundial) > > There seems to be continuing concern for the use of this name. As > before, there seems to be no other reason to refer to these non-linear > gnomons as "bifilar" other than the total lack of any better > terminology! The new BSS glossary does not even list the term, > "bifilar". > > After much consideration, I think a better term would be "bi-gnomon". > > This would help relate to the use of "bifilar" which seems to have been > used since 1920 but improve and broaden the definition. As Chris Lusby > Taylor wrote: > >Many recent so-called bifilar sundials merely use the > >intersection of the shadows of two rather arbitrary lines/curves. > > We might use the term "intersecting gnomon" or "bi-style" except that it > seems clumsy. If we accept the definition of gnomon as any type of > shadow casting object, we have a description of the physical dial. > > My thanks to Frans Maes for the posting of more views of the Appingedam > dial and the English translation. He has produced a very richly > illustrated site with valuable references. > > Claude Hartman > 35N 120W > >
