Dear Gianni, I like your explanation and I like the extra comments too.
You have: P1 on the equinoctial line and P2 on the horizon line This is good in theory but not so good in practice. For example, my line for Bab = 11 does not run as far as the equinoctial line or the horizon line!! Several other lines do not reach one or other of the equinoctial line and the horizon line. Another practical problem is that P1 and P2 can be quite close together and a small error in either will make for a large error in the extension towards the summer solstice curve! I very much agree with this: When a friend asks me a suggestion to draw a sundial, I always recommend him a sundial that marks the hours to sunset, that is a sundial with italic hours... My practical problem here is that it has taken me 20 years to find a client who agrees with this suggestion :-)) Now, when I look at the finished sundial, people keep coming up to me to ask, "How do I tell the time, the REAL time?" I explain that Babylonian hours and Italian hours ARE real times but this is not the answer they want. "OK," I have to say, "take the average of Babylonian and Italian hours and you will find the time on an ordinary sundial!" It is VERY nice to have an Italian Hours sundial so close to home!! Cordiali saluti Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
