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
