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    Re: Agnostic gnomon and horary error
    From: Frank Reed
    Date: 2024 Jun 4, 06:28 -0700

    There are additional clues in the structure that you all may have missed, I think (or did I miss someone mentioning this?).

    The armillary sphere has two other declination circles, and they are, of course, the tropics of Capricorn and Cancer. What do they tell you about the latitude of the sphere, as built? Closer to 48° or 41°??

    There is also one additional longitude arc. See it? Can you figure out what that represents? I'll give you a hint: it's 72° away from the central meridian arc of the sphere, and it's only on one side of the sphere, facing the camera in the book cover. Notice that this longitude arc crosses the sphere's prime vertical arc rather near the spot where the tropic of Cancer arc crosses the prime vertical arc. Those three arcs: Cancer, Prime Vertical, and the unique longitude arc form a small spherical triangle towards the top of the sphere. See that triangle? I believe that its size is quite sensitive to the latitude for which the sphere was constructed.

    I should add that I have never studied this sphere beyond its fundamental sundial features, which I'll get back to in another post. The details I'm adding above are just some things that I spotted this morning.

    Oh! I took some photos for your measurements on Sunday during lunch break from Lunars. :) I'll send those in about an hour. I have to run some errands now.

    Frank Reed

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