Hi Chris, Our calculations are based on the theoretical sunrise and sunset, when the altitude is zero. Refraction, semi-diameter and horizon all affect the actual sunrise and set, the observation of the first and last rays of the sun. I believe Stonehenge is in the magical location where the angle between summer and winter solstice events are 90ยบ apart. I need to check some references, Hawkins etc, to check if my memory of this trivia is correct.
Regards, Roger Bailey -------------------------------------------------- From: "Chris Lusby Taylor" <[email protected]> Sent: Monday, April 27, 2009 8:02 AM To: "Frank Evans" <[email protected]>; "Sundial" <[email protected]> Subject: Re: sunrise > > At 55 degrees north, you are not far from the latitude (55 deg 45') where > the midwinter and midsummer sunrises and sunsets are at 045, 135, 225, 315 > degrees. So declining dials at 45 degrees to N-S have extra magic. I > wonder > that Stonehenge wasn't built at this latitude. > > Chris > 51.4N 1.3W > > ----- Original Message ----- > From: "Frank Evans" <[email protected]> > To: "Sundial" <[email protected]> > Sent: Monday, April 27, 2009 3:18 PM > Subject: sunrise > > >> Greetings, fellow dialists, >> Am I correct in thinking that the earliest that a declining dial can >> begin to tell the time is when the sunrise amplitude lines up with the >> amount by which the dial is declining, for instance, sunrise bearing 080 >> deg., dial plate declining 10 deg east? It seems that with both greater >> and lesser sunrise amplitudes the dial will start work at a later hour. >> Am I right? >> Frank 55N 1W >> >> --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
