Willy
For my Elementary Schools program of walk-on dials I have incorporated a single
analemma; for High Schools I have used the double analemma. In both cases I
also mark the zodiac axis. The single analemma provides mean time during
school hours with a maximum error of around 5 minutes (within the reading error
of the personal shadow). The double analemma has a maximum mean time error of
about 3 minutes and an absolute mean time error of around 30 seconds for the
whole dial. In all cases the longitude correction is built in.
There is not much extra work in making the double analemma.
Embossed bronze survey tablets are used for the key hour and date marks. I use
a home made embossing press made from an old 20 ton lorry jack. The bronze
markers are supplemented with painted decoration; the paint can easily be
renewed every 7 years or so using the bronze markers as guides.
While the objective of sundials are no longer the determination of accurate
time, I find the folk today expect to find mean time. I provide a notice which
explains how the students can compare mean time and sun time directly from
their dial.
Brian Albinson
3441, Wellington Crescent, North Vancouver, B.C. V7R 3B3, Canada
Phone 604 980 3475
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