Roger,There's a direct solution to this problem - but it seldom if ever shows up in dialing texts. Since it's so seldom presented, I thought list members might be interested in seeing the equation. I've attached a very small pdf that gives the equation (in my preferred form - there are actually several ways to attack this) and solution for this particular instance.
Fred Sawyer----- Original Message ----- From: "Roger Bailey" <[EMAIL PROTECTED]> To: "Sundial Mailing List" <[email protected]>; "Frank King" <[EMAIL PROTECTED]>
Sent: Wednesday, July 11, 2007 12:26 PM Subject: Re: Help Oscar! This advice is good as far as it goes but if the class repeats the experiment with a vertical gnomon six months later they will find that the hour lines are very much different. Will this destroy their trust in science? I hope not and their teachers will use this as an opportunity to introduce another topic, the sun and seasonal change. The ancients building megaliths etc learned a lot about their world by observing the sun. Unfortunately a lot of fires were burned and virgins sacrificed to get the sun to come back. The important thing for teachers today is to get the kids to keep asking why and not to take things on faith from all knowing teachers. A little quiz is appropriate here. Calculate the time for the sun to be at a azimuth of 45º for the summer and winter solstices for a given latitude, say 50º. The difference is remarkable. I found solving this particular solution of spherical trigonometry somewhat more difficult than the usual solutions where the time is known and altitude and azimuth are calculated. Regards, Roger Bailey
SolveforT.pdf
Description: Adobe PDF document
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