My Smiling Red Face

[William S. Maddux]

John,   I am happy (though embarrassed) to report that I am now convinced that most of the edge problems I saw in the proposal photos were apparently artifacts.  They seem to have been introduced into the PDF images by the compression/decompression processes.  Perhaps some spatial periodicity aliasing was at work. There are suspiciously  moire-like patterns in panel areas, as well as less regular changes somehow introduced at the apparent edges.   However, this doesn't alter the bases for the calculation of time-error vs edge-error that I posted on June 25th. Photos did not enter into that:   >... Thus at that distance, the time required for the 1/2° degree >wide sun to pass through the meridian plane would be very >nearly 2 minutes of time during which it would move >about 9.3 inches relative to the style edge.  Therefore, if the >style's edge were to be laterally displaced 3 inches, the >resulting error in time would be about 3/9.3 x 120 = 38.7 seconds >of time, and a 1 inch wrong location of the effective edge would >cause nearly 13 seconds of error. ... .   which spoke to your comment:    > .....  By placing one eye at the base of a style, we could look >straight up the edge of the styles. We did see very slight >undulations in the styles, but we guesstimated that they were >only between I and 3 inches, a very small amount if you consider >the enormous size of the sundial. These could only affect the >precision of the dial by a few seconds.  Time will tell!   Indeed, time has already told me some things.   Continued best wishes for your endeavors,   Bill