I do not know if bifilar dials are or not an outstanding contributions to sundialing in the XXth century... Among other reasons, because I know the general idea of them (from Scientific American) but not the details. However, as far as I know bifilars were invented in 1922 ... I think that these and the conical sundial are the best ones for a single reason: they are completely classical, ie., they could as well have been discovered in the XVth century
or in any other. Best regards, Anselmo -
