To ensure I am not duplicating something that has already been done, has anyone developed a formula for showing the error a ring dial (with a fixed gnomon say 40N) will read when in different latitudes? I am trying to express more detail than I have in bold below but I'm not sure such can be easily done, considering the variation in sun altitude throughout a day in different latitudes. Or have I already expressed the situation about as well as it can be described to a general audience?
Also, what ring dial graphing programs are out there? I am just aware of SONNE.
Thanks,
Thad Weakley
42.2N 83.8W
Ann Arbor, Michigan
RING DIAL:
The Ring Sundial is an instrument that gives you the current time by casting a bead of light rather than a shadow.
- Hang the sundial from the chain to have the maximum exposure to sunlight.
- Position the sundial to allow sunlight to shine through the hole on the outer ring. The bead of light that is cast on the inner ring indicates the hour and the season.
Such dials are made for particular latitude. While these dials are readable in other latitudes, there will be error as easy calibration isnt available. In general in lower latitudes the dial will read fast in the a.m. and slow in the p.m. In higher latitudes the dial will read slow in the a.m. and fast in the p.m.
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