Jack,

Try out my calculator! You can specify a time zone meridian for the dial at its original location, or at its new location, or both. If there is an effective longitude change, it'll tell you how to position (twist) the dial on the wedge and how to orient the wedge itself, turning it away (rotating it ) from the meridian line.

Steve


On 2023-04-02 3:59 p.m., Jack Aubert wrote:

I thought about this briefly.  I had always thought that the purpose of the shim or wedge adjustment was to tip the dial north or south so that dial is at the latitude it was originally designed for.  If the original dial has a built-in longitude correction, that could also be factored into a wedge which would have both a north-south and east-west axis.  But a wedge would not work if it moved the gnomon out of alignment with the with the rotation of the earth (or the celestial sphere).  I think a longitudinal adjustment would only work if he original dial had a time-zone offset included by rotating the hour lines with respect to the origin of the gnomon.

Does this make sense?  It sounds like a good project for a 3-D printer.

Jack

*From:* sundial <sundial-boun...@uni-koeln.de> *On Behalf Of *Steve Lelievre
*Sent:* Sunday, April 2, 2023 5:16 PM
*To:* Michael Ossipoff <email9648...@gmail.com>
*Cc:* Sundial List <sundial@uni-koeln.de>
*Subject:* Re: Adjusting dial to new location

Michael,

Yes, I recognize that to get Mean Time involves Equation of Time adjustment and that Equation of Longitude can be handled there to give Standard Time (or DST).

But anyway, my inquiry was to seek an online wedge calculator. Nobody identified one and  a week seemed an adequate wait for responses, so I've just written one.  Anyone who's interested, please see

https://sundials.org/index.php/teachers-corner/sundial-construction/367-easy-dial-adjustment-for-your-latitude

Cheers,

Steve

On 2023-04-02 1:41 p.m., Michael Ossipoff wrote:

    I just want to mention that the shim under the north or south edge
    of the dial is only for latitude. Longitude is corrected-for by
    changing the constant term of the Sundial-Time to Clock-Time
    conversion.

    But usually Sundial-Time, Local True Solar Time, is what I’d want
    from a sundial.

    On Sun, Mar 26, 2023 at 14:30 Steve Lelievre
    <steve.lelievre.can...@gmail.com> wrote:

        Hi,

        Can anyone point me to an existing online calculator for
        making a wedge
        to adjust a horizontal dial to a new latitude and longitude?

        I am not asking for an explanation of how to do the
        calculation; I just
        want to be able to point people to a calculator that has
        already been
        proved on the internet. It should use the original location
        (latitude
        and longitude) and the new location to calculate the angle of
        slope of
        the wedge and the required rotation from the meridian.

        Many thanks,

        Steve


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