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    Re: Agnostic gnomon and horary error
    From: Geoff Hitchcox
    Date: 2024 Jun 2, 06:49 -0700

    You can measure it in the photo. The style of the thing does not make it possible to re-tilt it in any efficient way, so there it is, wrong by 7° for over sixty years!

    I think I may have a solution to this Sundial issue Frank.

    Because Amazon allow you to download a "sample" of the Sundials Book (if you have a Kindle), I downloaded the FREE sample of the Sundial book to my Kindle. Using a school-boy protractor, I measure the angle of the Gnomon as being near 41 degrees, not the 48 degrees I measured on your Black and White image (or the photo on the Amazon WEB Page). I have attached my screenshot of the Kindle cover - I would be interested to see if you also get near 41 degrees Frank.

    My thoughts are that the Black & White image you have (and the Amazon Web page) is a quick and dirty photo someone took to just show what the book cover looks like - with an inherent 7 degree rotation. The Kindle cover is the 'better' true digital image of the cover of the book, that (on my phone screen) has about a 41 degree Gnomon.

    So I think the Treworgy Sundial is probably just fine, and I agree with Chuck_V that the "actual sundial" should be measured.

    So maybe it is not true - that the camera "never lies".

    Regards, Geoff Hitchcox, Christchurch, New Zealand.


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