Polar ceiling sundial

[Anselmo P�rez Serrada]

Hi, everyone!   Maybe some of you didn't notice that if you lean the mirror towards the South so that it's slope equals half of your latitude then (a small hand-made wedge would do the job quite well) you get a polar sundial on the ceiling, with all its analemmas paralell to the meridian line...   By the way, I think the best method to draw the meridian line on the ceiling of a room is the obvious one: consult in an almanac which is the time for noon in this day for your place. Mark the bright dot on the ceiling four hours later and four hours before that moment and connect both dots: the mediatrix of this line approximates very well the meridian line. Of course, you can take as well a mason's plumb and mark its shadow on the floor at noon. Then, with a mirror and a laser pointer you could draw it on the ceiling, but I do not think it would yield better results.    Somebody's got a better idea?     Anselmo Perez Serrada [ 41.63 N   4.73 W] P.S.: I have pasted the five web html's by Fer de Vries on 'computing flat sundials' and dumped them on a pdf file so you can print them more easily. You can download it from his (really fine!) web page at http://www.iae.nl/users/ferdv/.