Hello Robert, Calculating the angles for the hourlines isn't complicated if the dial is translated to an equivalent horizontal sundial. Start to calculate 3 angles:
sin v = sin phi . cos i - cos d . cos phi . sin i v is the style height and also the equivalent latitude where the dial is horizontal sin b = cos phi . sin d / cos v b is the angle of the substyle, relative to the line of greatest slope. With v and b it is known where the polestyle will be. tan ts = sin i . sin d / ( cos phi . cos i + sin phi . sin i . cos d ) ts is the hourangle at what time the shadow of the style falls on the substyle. Use ts as a longitude correction to calculate the horizontal dial at latitude v. Use the usual formula for an horizontal dial tan z = tan t . sin v in which t is corrected for longitude ts. z is the angle of the wanted hourline relative to the ( known ) substyle. Correct values for b , ts and z to the right quadranr if necessary. I think this is the easiest way to do the job. Best wishes and happy dialing, Fer Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E ----- Original Message ----- From: Shadow Maker <[EMAIL PROTECTED]> To: <sundial@rrz.uni-koeln.de> Sent: Friday, March 23, 2001 6:58 PM Subject: Reclining/Declining > I have built some horizonal, vertical and vertical/declining dials and I am > now ready to build a reclining/declining dial, that will compensate for > standard time (that part is easy). > > I have read what Mayall/Mayall, Waugh and Rohr have written about the > layout process. I would prefer to use the trig formulas for SD, SH and > HourAngles because I can use them in a PostScript file that will render the > dial face and print out the values of all of the angles. Rohr does show the > formulas for SD and SH but, like the others, he recommends a graphic layout > method instead of a computational method > for the hour line angles. I was hoping that all of the trig formulas would > be available, but can't find them. Waugh says that older editions of the > Encyclopedia Britannica had all the trig formulas but dropped them a hundred > years ago. > > Can anyone help? > > Robert Hough > [EMAIL PROTECTED] > > _________________________________________________________________ > Get your FREE download of MSN Explorer at http://explorer.msn.com >
