Hi Wee-meng,
For most dials, if you build it correctly and for whatever reason you get a consistant (say 7min) error throughout the year, you can make a correction for it. Just add the correction to the equation of time (ET) or with some dials such as horizontal ones just adjust the way you mount them. With decrepencies between clock time and dial time in the upwards of a couple of hours with some locations, times of year, daylight savings time, etc. I try to not get too anal with my expectations esp. with smaller dials. Most smaller dials only show the time within a couple minutes anyway.
The most desirable case of any such small discrepency is to have it very consistant throughout the year. If it is then you have the wonderful satifaction of having done an excellent job with layout and construction.
Good luck!
Thad Weakley
Ann Arbor, Michigan USA
42.2N 83.8W
wee-meng lee <[EMAIL PROTECTED]> wrote:
wee-meng lee <[EMAIL PROTECTED]> wrote:
Hi,
Another question I have, in books and write ups that I've read, often times,
there are references to longitude and latitudes to specify the dials/gnomon
sizes of sundials.
When I read about longitudes/latitudes in GPS articles, there are loads of
different types of projection used. A commonly used one by GPS is called
"WGS84". In my GPS, if a point is specified using the wrong projection, it
may be way off.
What's the commonly used projection system used by Sundial makers to specify
locations?
Do we need to bother with such accuracy if we can live with 5-10 minute
errors?
Thx,
weemeng
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