Hi Fer & others: Let's say you have a spherical room, built like a planetarium, where the walls curve up into the ceiling and you locate your mirror in the center. (Actually, the room would be a quarter sphere, like an orange segment, with one flat side being the floor, and the other flat side the southern wall with the window with mirror).
Would the sunspot be perfectly round all the time? Also, what would the hour and declination lines look like? (Like the lines on a hemispherium?) Would this be called an "Equatorial Ceiling Sundial"? John John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: <http://www.sundialsculptures.com> ----- Original Message ----- From: "fer j. de vries" <[EMAIL PROTECTED]> To: "sundial" <sundial@rrz.uni-koeln.de> Sent: Friday, January 11, 2002 7:19 AM Subject: Polar Ceing Dial > Diallists, > > In my message of 2002-01-09 about the limits of a polar dial on a ceiling I > ended with: > > < Who has an inclined ceiling, higher at the south end? > < Won't that be better? > > I wanted to know this for sure and I started with a ceiling with an > inclination of 160 degrees in stead of 180 degrees. > A difference of 20 degrees as is shown in the attached picture. > > The mirror now gets an inclination of 0.5 ( phi - 20 ). > For latitude 52 this is 16 degrees. > > The pattern on the now inclined ceiling also is a polar dial. > > I did not look for the extreme limits, but just gave it a chance. > > Following the same procedure the polar dial is cut off at about 3.5 hours > before and after noon and it is seen that the mirror is less inside. > (distance CB ). > > At the left the pattern for a south facing dial though CM with (pin)gnomon > CB is drawn. > > The mirror is at distance CM from C and that is shown with the line KL. > > At summer solstice the mirror will be in the shadow of the edge of the > ceiling untill about 3.5 hours before noon and is shaded again 3.5 hours > after noon. > > So this configuration will work 7 hours at summer solstice. > A great improvement compared with an horizontal ceiling. > > I only need to rebuild my house............. > > Best wishes, Fer. > > Fer J. de Vries > [EMAIL PROTECTED] > http://www.iae.nl/users/ferdv/ > Eindhoven, Netherlands > lat. 51:30 N long. 5:30 E > > > > > >
