In a message dated 4/6/00 1:48:12 PM Eastern Daylight Time, [EMAIL PROTECTED] writes:
> One presentation at the recent BSS Conference > referred to a series of planned dials using sunrays passing through > circular holes onto walls/ceilings. This brought to mind recent postings > which mentioned placing a spherical 'bead' in the aperture so that the > sunlight was passing through an annulus to yield a light spot with a > sharp central shadow - if I remember it correctly. A sharp shadow (or a sharp spot of light) seems to be a holy grail of sundialling--very difficult to achieve, and rarely seen. It can not be accomplished without a focusing mechanism of some sort. I believe that the arrangement that you have described will created a blurred, not sharp, central shadow. Nonetheless, I think such a central shadow would improve the accuracy and aesthetics of the wall dial, despite any blurring. Bill Gottesman Burlington, VT 44.4674 N 73.2027 W
