>Hello Dialists : > >I've got a question that's always bugged me. As I'm more of an artist than >mathematician, I doubt that my answer is the correct one and I'm sure many >of you geniuses out there know the answer. > >I'm sure many of you have seen time lapse photography of the little circle >that Polaris circumscribes around the North Celestial Pole in the northern >night sky. This is because it is about 1/2 a degree away from the N.C.P. > >If you orient your sundial north by Polaris when it is on the meridian, then >there will be no time error, because the dial will be pointed due north. >Right? > >But if you orient it when it is due east or west of the meridian, the >sundial will be turned the maximum distance from true north (1/2 degree) and >the maximum time error will result. How large is this error in seconds of >time? > >Here's how I tried to solve it: > >If the sun moves 15 deg./hr. then it moves 15 deg./ 60 min.= 1 >deg./.25min.=1 deg/15 sec.=.5 deg./7.5 sec. > >Is this the answer: 7.5 seconds? > >I've got a feeling that I've oversimplified the problem. I bet the answer >turns out to be some bellcurve with an error which changes throughout the >day. It's probably something only T.J.Lauroesch and J.R.Edinger,Jr. can >solve! > >John Carmichael
John You have over simplied. The error in time read with such an error in placement depends upon the location that the dial was made for and the time of year and day. I suspect, without further detailed analysis that the error that you give is close to the upper limit. For a sundial made for a location in the tropics the sun passes directly overhead a some times during the year. On those occasions the dial will read correctly no matter what the orientation of the dial. So the error due to error in placement is somewhere between 0 and some upper limit. Dan Wenger Daniel Lee Wenger Santa Cruz, CA [EMAIL PROTECTED] http://wengersundial.com http://wengersundial.com/wengerfamily
