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From: Geoff Hitchcox
Date: 2024 Jun 13, 21:32 -0700
In my previous message I referenced an article that mentioned that a Fred Sawyer had a "formula" for moving a Sundial in Latitude.
I found the "formula" in the Fred Sawyer article on Page 14 in this PDF document.
So at last we have a formula, but with a caveat that it is for a Horizontal Sundial, that I'm assuming can be applied in the armillary sundial case.
Using the "formula", we can quickly find the time error caused purely by the Latitude change.
Using Adrian's Sundial readings (he was a little more careful than I was reading Frank's two photos).
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First Photo:
Values to place in the Sawyer Formula.
M = -7.2753°
D = 13.85°
Sundial should be 3' 17" Fast (due to Latitude error).
Adrian Observed +9 minutes.
I assume the difference (5' 43") must be Longitude error.
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Second Photo:
Values to place in the Sawyer Formula.
M = -7.2753°
D = 14.51°
Sundial should be 7' 19" Fast (due to Latitude error).
Adrian Observed +11 minutes.
I assume the difference (3' 41") must be Longitude error.
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Regards, Geoff Hitchcox, Christchurch, New Zealand.
