"Bi-filar" seems to be used for want of a better term. Perhaps "bi-style", "duo-style" or "double style" would be better when referring to the intersection of two shadows.
One example was described by Gianni Ferrari: Another example was shown at the Reutte, Austria, sundial competition in 1998. This was submitted by Rafael Soler and called a "Bi-Filar" sundial. It marked time by the intersection of the shadow of a horizontal disk and its vertical support rod. Attached is a small photo of this novel design. A larger photo is in my report of the Reutte competition at the 99 NASS Conference on the NASS web site: www.sundials.org Claude Hartman 35N 120W Attachment converted: Macintosh HD:soler2a.jpg (JPEG/JVWR) (0000FC7B)
