Dear Brooke, You ask:
> Can you say more about how to read the photograph > you attached? Yes. On a given day around Local Mean Solar Noon you watch the splodge of light from the aperture nodus cross the analemma. The analemma is, in some sense, drawn with a very wide brush and it takes four minutes for the splodge to cross this width. That's one degree of hour-angle. When the splodge is half-way across the time is local mean noon. The analemma is broken up into strips. The design has 366 strips, one for every day of the year including 29 February, but the strips at the solstices are impractically thin. You note which strip the splodge is travelling along and this gives you the date. Fortunately, at the end of February the declination is changing quite rapidly so the strips are quite substantial and even the (almost) quarter-height strip is easy to see. > Is there an existing dial that incorporates > detection of 29 Feb? The photograph IS of an existing dial. The limitations of the Gregorian calendar mean that it will drift out of sync with the dates after 40 years but the design life of the building isn't much more than that and I won't be around to bother about it!! Life would be so much better if we had the Omar Khayyam calendar that Roger Bailey was writing about. That would take a very long time before things went out of sync. All the best Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
