Hello All: I'm glad the azimuthal discussion didn't die as I think we are finally coming to grips with understanding it. I think it is that it is important to point out that much of the confusion on this subject has resulted from poor understanding and misuse of sundial terms. The terms "Dali, azimuth, azimuthal, Singleton and monofilar" have all been mistakening used interchangably in this discussion causing a great deal of frustation and lost time. Before we go any further I think that we should first all agree upon the proper nomenclature, so we are all speaking the same language.
According to The John Davis Glossary, a monofilar sundial is a dial "in which time is marked by the point where the shadow of thread held between the dial face and the sun intersects a set of date lines." This definition seems to apply to either to a Singleton dial (polar axis thread (or cable) gnomon with EOT hour lines and date rings) or to an azimuthal dial ( vertical thread or cable gnomon with unwrapped analemma hour lines and date rings). It seems that the only important requirements of a monofilar dial are that it have date rings and use a string type gnomon. If an azimuthal Spin dial has a vertical cable instead of a rod for the gnomon, then it also fits perfectly the Davis definition of monofilar. We need to come up with and decide upon a term that describes a Singleton sundial. Should we just continue to call it a "Singleton" for lack of something better or should we call it monofilar and ask John Davis to modify his definition to exclude azimuthals? John Carmichael p.s. I see no reason why a Singleton has to have a thread (or cable) gnomon. Won't it also work with a traditional solid triangular gnomon? Since monofilar means "single thread", it seems that it's definition should be the following: "a sundial that uses a thread, string, cable or rod", with no date ring requirement. This would make my current cable sundials monofilar. Or should I call my sundials "string sundials"?