Dear John, I am not sure the Chief Engineer fully grasped what is going on though he has indeed appreciated that, at the required moment, both the altitude and the azimuth of the sun change from one year to the the next.
In a crucial sentence he asserts: Each year, the center of the sun is slightly offset from other years by just a few horizontal or vertical arc-seconds relative to the timing of the required azimuth/altitude position of the sun. Even over the 10 years I quoted, the horizontal offset has a range of about 3 arc-minutes (NOT arc-seconds) and the vertical offset has a range of about 13 arc-minutes (a significant fraction of the solar diameter). He is right that the horizontal range affects the time by well under a minute but the much larger variation of the vertical range (or solar altitude) means that even when the azimuth error is zero the circle of light can be too close to or too far from the vertical slabs by a significant amount. If I had been consulted, I would have suggested that the Great Seal should be a little smaller so that it will always be wholly illuminated at the crucial instant! I don't like the way that part of the Great Seal is left in the dark, but maybe there is some subtle symbolism there that only experts in the U.S. Constitution will understand. A thing that bugs me more is the time that has been chosen... Most of the documentation says 11:11 which I take to be 11:11:00 Mountain Time, but the Chief Engineer sometimes says 11:11 and sometimes 11:11:11. That's simply being inconsistent but, worse than that, both are historically incorrect. One of the videos stated that the time commemorates the Armistice of 1918. Without qualification, that doesn't mean very much. The Armistice was actually agreed about 05:00 Paris Time on 11 November 1918 and the signing process lasted from 05:12 until 05:20. The agreement was that the Armistice should "take effect" from 11:00:00 Paris Time. In those days, France had the good sense to use GMT so the agreed time was 11:00:00 in Britain too. In those days Germany used GMT+1 and the agreement spelt out that the Armistice should take effect at 12:00:00 German Time. If the good people of Anthem really wanted to commemorate the Armistice they should mark it at 05:00:00 Mountain Time each 11 November. This would be before sunrise but that's a detail. I am very happy for them to use 11:00:00 Mountain Time and to use a sun marker but where on Earth do they get the extra 11 minutes from? Never mind the extra 11 minutes 11 seconds? I do wish the Chief Engineer had consulted me :-) Very best wishes Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
