Hi David,
The starting point for making moondials must be Michael Lowne's classic article
"Moondials and the moon" in BSS Bulletin 17(i) pp3-12. In it, amongst other
things, he shows that the value of 48 minutes for the daily offset is in fact
not the best number to choose.
If you want something more exotic than just a sundial with a conversion table
in the manner of the Queens' College dial, you could have one with 15 separate
chapter rings, each one applicable for two days of the moon's age (symmetrical
for waxing and waning). This is what the likes of Henry Wynne did on some of
his very large horizontals. There is also a reasonably well-known one in slate,
I think. I've never seen it done on a vertical east dial - could be an
interesting pattern.
The biggest problem with these schemes is knowing the age of the moon: unless
the user looks it up in an almanac, online or with an app, you need to have
little diagrams to match to the moon's appearance.
Regards,
John
-------------------------
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://www.sundialsoc.org.uk/bulletin.php
________________________________
From: David <da...@davidbrownsundials.com>
To: Sundial list <sundial@uni-koeln.de>
Sent: Wednesday, 14 May 2014, 7:29
Subject: Moon dial.
Dear All,
I have had a request to construct a moon dial for a vertical east-facing wall.
This is new territory for me.
Can anyone point me in the direction of sources/computer programmes that would
give me guidance?
David Brown
Somerton, Somerset, UK
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