Dear Sundial Enthusiasts, Some sundials don't need to have their readings related to clock time, and thus have absolutely no need for any corrections for longitude, equation of time, or even daylight savings. I offer two examples. Perhaps members of this List will suggest others.
My first example is a sundial showing hours remaining until sunset - that is, a sundial with Italian hours labeled in countdown fashion. The Moore's Field sundial, installed at a tiny Vermont (USA) airport to identify the airport and to tell hours until sunset, is a dial needing no corrections to perform satisfactorily. The dial is accurate to within a few minutes, which is sufficient, even though some of the aircraft using the field are required, by regulation, to land by sunset. Compendium 4-1 (March 1997) contains an article on this sundial. Another example of a sundial needing no corrections was mentioned to me by George McDowell, who said he was thinking of designing a dial to indicate relative sunburn danger. Installed at a swimming pool or beach, this type of dial wouldn't even need any hour lines - regions of color would alert the sunbather as to when (s)he would burn most rapidly. (How did that dial turn out, George?) My best to all, Mac P.S. My 36-page manual on designing and building an hours to sunset sundial is still available via email. It's free, and worth every penny. :-)
