Hello dialists: Let's say you want to build a large sundial using the ground as the dial face. The ground is somewhat irregular and not quite horizontal. You decide to draw the hour lines, not by calculation, but by using the technique of building the gnomon (style) first and then marking the position of the shadow on the ground at selected time intervals using clock time and correcting for EOT and longitiude.
You draw the hour lines from the edge of the dial face to the dial center, tracing the shadow. Since the ground is irregular and not flat, you notice that the shadow line is not straight, but irregular also, depending on the terrain. This produces hour lines that are not straight. Because the sun's declination changes during the year, changing the angle that the sun strikes the style, will this technique produce the same shape hour lines if it is done at any time of the year or is the declination irrelevant? Will this technique produce the same shape hour lines at any time of the year? I think it should. but I'm not sure. John Carmichael Tucson, Arizona
