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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