Very clear, David. Thank you also for the marvelous photo . My doubt is for plane dials however oriented : in this case does exist a shape of the gnomon good for all the hour lines ? This could be a fine math problem to solve, but I'm lazy !
Best regards Alberto Nicelli > ---------- > From: David Higgon[SMTP:[EMAIL PROTECTED] > Sent: martedì 15 settembre 1998 10.18 > To: all > Subject: gnomon shape and EoT > > <<File: CONNOISB.JPG>> > Alberto, > > Yes it is, is the short answer. In fact you will need two shaped gnomons > - > one for the spring and one for the autumn. For each gnomon to stay in one > piece, it has to have some notional diameter to which the EoT is added or > subtracted. In the morning one side of the gnomon will cast the shadow, > whilst in the afternoon it will be the other side. This means that at > noon > there are two parallel lines, separated by the notional diameter of the > gnomon. This allows for the change of which edge of the shadow you read. > I don't know if I've explained this as clearly as I should, but if you > need > more information, drop me an email. > > My father makes an equatorial dial with just such gnomons and I have > attached a photo of one - I hope it's not too big a file (apologies if it > is). > > Regards, > > David Robert Higgon > London >
