Hello Steve, Reading your PS in one of your messages ( see below ) :
Also a bifilar sundial can have a built in correction for EoT. It is just the same as a usual polestyle sundial with a nodus where I can draw EoT curves on the dial's plane. All you can show on a usual dial can be showed on a bifilar dial too. In fact a usual dial is just a simplification of the original bifilar dial. Place 2 threads parallel to the dial's plane AT THE SAME HEIGHT. The shadow caster now in fact is a single point of a ( not present ) perpendicular pin on the dial's plane. And with just a single point I can read all the phenomenae on a usual dial. Back to the bifilar dial : A bifilar dial can be constructed in such a way that the hourlines ( for local suntime ) are equi-angular spaced. Than it is also possible to correct for EoT and/or longitude by rotating the hourscale. So we have at least 2 possibilities to correct for EoT with bifilar sundials. Happy dialling, 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: Steve Lelievre <[EMAIL PROTECTED]> To: Sundial mailing list <sundial@rrz.uni-koeln.de> Sent: Friday, February 25, 2000 9:24 PM Subject: Re: Azimutha Sundial (once more) > P.S. Come to think of it, surely a bi-filar can never incorporate EoT > adjustment because each shadow point represents two instants in the year, > doesn't it? >
