Helo Rod, This isn't new and you are correct. Have a look in Compendium, the bulletin of the North American Sundial Sosciety (NASS) issue december 2001, for is an article about this subject.
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: "Rod Heil" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Sunday, January 27, 2002 5:55 AM Subject: the thick-gnomon problem > Please forgive me -- I am not well-versed in sundial lingo, although I > think I have a pretty good grasp of the concepts. > > I made a discovery today that is new to me, but perhaps not new to you > all. I have never seen it published anywhere. > > I have recently constructed a small wooden horizontal sundial. The > gnomon is 1/4" thick. So, on calculating my hour lines, the lines on > the left are 1/4" offset from the ones on the right. So far so good. > > Except that I was pretending to be the sun as I looked down on my new > sundial to see where my shadow would fall, and I noticed that for hour > lines south of (where the gnomon intersects the dial face -- I'm sure > there must be a name for this), the gnomon edge which cast the shadow > was not the one I expected, but the other one. > > I.e. If the sun is northwest of the sundial, the west edge of the > gnomon is the one casting the relevant, time-telling shadow. If the > sun is southwest of the sundial, the east edge of the gnomon casts the > shadow. If the sun is in the southeast, the west edge of the gnomon > casts the shadow. If the sun is in the northeast, the east edge of the > gnomon casts the shadow. > > Am I right so far? And so it would seem that hour lines that lie south > of where the gnomon intersects the dial plate should be drawn to > intersect the opposite edge than lines that lie north of it. > > Perhaps someone could rephrase all this for me, and then tell me > whether I'm correct or not? Thanks, > > Rod Heil > ~41.3 N 105.5 W > > __________________________________________________ > Do You Yahoo!? > Great stuff seeking new owners in Yahoo! Auctions! > http://auctions.yahoo.com
