Hi Tony: The bead in hole shadow sharpener was a discussion that I started on 5/5/99 about just such a device that I used on the alidade of an equatorial heliochronometer that I built. I will forward you my original message, but you can find the rest of the discussion and all letters to the sundial list at: Astroarchive website at: http:194.230.53.250/7/. Go to "read messages", scroll to "sundials".
If you'd like me to send you some xerox photos of my bead in hole shadow sharpener, let me know. John C. >Fellow Shadow Watchers, > 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. > >1. Does anyone have these postings conveniently saved or can recall >their approximate date? > >2. I also seem to remember noting that all postings to this mailing list >are archived somewhere so given the date and archive address my >correspondent could look them up for himself. > >Thanks in anticipation > >Tony Moss. > > > > > > >
