The Sundials program I wrote for PC and Mac draws ring
dials:
http://advanceassociates.com/Sundials/Lufkin-SUNDIALS-MAC/
Regards, Brad
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Thaddeus Weakley
Sent: Friday, August 05, 2005 4:25 AM
To: Sundial List
Subject: Ring dial corrections between latitudes
Dear Fellow Dialists:
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 isn’t 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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