Hello, everyone,
A recent NASS Compendium included an article on the use of a Shepherd's
Dial as a compass. The author reported orientation errors in field use
of up to 25 degrees in the hour either side of noon but 5 degrees or
less in other parts of the day. This is consistent with my findings from
with a similar dial that I tested last summer (although I didn't manage
quite the same accuracy in the non-noon period).
I'm currently designing a Capuchin dial adapted to a compass, but am not
expecting it to do well near noon either. The idea of portable solar
compasses based on altitude measurement is appealing because there is no
need to know time of day, but it seems inevitable that they're not going
to function well around midday while the sun hangs in the sky with
minimal change in altitude.
Am I missing some potential cleverness - given that I want a portable
dial with no need for a watch to determine time, would any other type of
dial be less prone to midday orientation errors? Are they particular
adaptions could be used to improve accuracy?
Cheers,
Steve
Herty, Frank B. (2014). A Shepherd's Azimuth Dial. The Compendium
[Journal of the North American Sundial Society], 21(1).
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