HI patrick: Thanks for your feedback. Actually, nobody has mentioned this yet but as a kid I remember that we used a pinhole to look at the image of a solar eclipse. Now I know that it is called a shadow sharpener...
There is one part of your message that I don't understand: >What I find interesting about the effect is whether or not it was used in >the design of meridian lines where a spot of light crossing a marked >meridian line was used to establish all sorts of astronomical parameters. >I suspect the variation in image distance was too great. Thanks again, John Carmichael Tucson
