Hi, John! > I think I'll just use hour, 1/2 hr and 15 min lines. > > Also, in order to be able to tell time with short shadows around noon in the > summer and to accomodate short people, it will be very important to mark the > hour lines as close as possible to the gnomon foot (where the people stand). > Correct?
I may be wrong, and it would be wise to verify this with Fer or someone else far more knowledgeable about analemmatic dials, but I see a problem with your vision of the dial: Analemmatic dials, as we have been discussing them, do not have hour *lines*. They have hour *points* only, on the periphery of the ellipse. It is the "responsibility" of the human gnomon to be tall enough to cast a shadow all the way to the points. This sets the scale of the dial somewhat, as a truly monumental dial would require Paul Bunyon (or at least Wilt Chamberlain) as a gnomon! You can't beat it by - * Drawing hour lines, from the hour points to the gnomon foot, because the foot moves with the time of year. * Drawing several "nested" dials at different scales (major axis length), because the entire dial, including the date line/scale, is proportional to the major axis. While you could draw lines connecting the corresponding hour points, the central date lines would be of different lengths, so the "gnomon" wouldn't have a unique point on which to stand. This also messes up your thought of painting footprints for different height users, because all users, regardless of height, stand on the same (date) point. Some just have to extend their arms over their heads, to get a long enough shadow. To some extent, the dial design corrects for the "shortcomings" of the users. Note that the date points for Summer are much closer to the North rim of the dial, and the hour points for Noon are much closer to the date line than 0600 and 1800. These automatically correct for the varying shadow lengths per time of day and time of year... Does this make sense? Dave Bell N37.29W121.97
