At 10:08 AM 10/20/99 +0100, Tony Moss wrote: >P.P.S. To bring this fully back on topic I can't remember if anyone mentioned it but, when using CDs as sundial discs, the 'Recordable' variety, used blank, give the clearest sun line. To test this use one that is half full when the recorded bit (nearest the middle) has a 'fuzz halo' by comparison. The very cheapest types have no printing either side so look best. >
Hi Tony, As you know from my presentation in Hartford, I have now used CDs in a sundial design. They were the hour markers for the test analemmatic dial that I laid out on my deck. Your comment is correct. For the best diffraction pattern, lines without pits would be best. In my case, diffraction did not matter. All I wanted was a flat, distinctive hour marker that would not cause tripping or snow removal problems. I found obsolete software disks from Sun Microsystems to be most appropriate, in particular various versions of "Sun Patches". An alternative choice would have been the Beatles recording of "Here Comes the Sun" and "The Fool on the Hill" Roger Bailey On the Hill at N 51 W 115
