I have read only today the messages concerning the Dali dials and the Azimuthal dials (Arthur Carlson, etc).
The sundials described by Arthur Carlson in his messages coincide , I think, with the dials that I have called Monofilar and I have described in an article published on "The Compendium" - September 1998. In these sundials the hour is marked by the intersection of the shadow of a rectilinear pole (that can be placed in a whatever way ) with a group of date lines having a given shape. A program (SUND98P) with which one can calculate many examples of these sundials (on a whatever plane) has been distributed with the digital edition of The Compendium ( September 1998) : if Arthur wants a copy of this program I can send it in a file attached. The Azimuthal dial (as that sent by Fer de Vries) is only a particular case of this family of sundials: when the pole is vertical, the plane is horizontal and the date lines concentric circles. In general all Azimuthal Sundials need only the style vertical (the plane may be declining and the date lines whatever) I attach a different example of Monofilar Sundial , realized with the program SUND98P : vertical plane declining 40 West; the pole is horizontal (f.e. the edge of a balcony) and the date lines are vertical straight lines. A different system to have the time corrected for EoT is that I have introduced in a relationship at the VIII Italian Gnomonic Seminary (March 1999), that has been published (in Italian) and that I hope will be published soon on "The Compendium" The dial described is an interactive sundial in which the observer lets flow an indicator (f.e. a finger ) on a pole (of any form and graduated in hours) and stops when the shadow of the indicator falls on the date line of the day (whose shape depends from the kind of time and from the shape and the position of the pole) In the point where is the indicator the observer can read the hour . This type of sundials (interactive) can have realized with a whatever kind of hours ( ancient or modern) and time (Local, Standard, etc.) Regards Gianni Ferrari --------------------------------------------------------------------------- Ing.Gianni Ferrari Via Valdrighi, 135 41100 - MODENA (ITALY) EMail : [EMAIL PROTECTED] http://members.tripod.com/meridiane/index.htm --------------------------------------------------------------------------- Attachment converted: Macintosh HD:monof.gif (GIFf/JVWR) (0000C934)
