By “auto-correction”, I refer modification of the dial, so that it will
directly read Local-True-Solar-Time (LTST) at your latitude at your
standard-meridian instead of where the dial is.
…
Auto-correcting for longitude by rotating & tipping the dial is a
“retrofit” longitude auto-correction, as
Depending on your choice of rotation axes, only two rotations are
needed, one for the elevation of the pole and one around the gnomon for
longitude correction. These are the two that correspond to the actual
changes needed.
If you are using the three orthogonal x, y, and z axes, then three
Assuming that a dial should read only local solar time is a rather
limited view. While it might be of interest to the dial purist, it is
not particularly useful to the general population and often requires a
lot of explanation. And it makes us seem like an eccentric clique. The
dial produces a
At a new location, a dial must end up with the style parallel to the
polar axis - but how do you achieve that using a wedge? Assuming you
start with the dial at the new location on a horizontal surface with the
sub-stile line on the local meridian, the required sequence is to rotate
it about
-- Forwarded message -
From: Michael Ossipoff
Date: Tue, Apr 4, 2023 at 09:53
Subject: Re: Adjusting dial to new location
To:
The combination of rotation about the vertical axis, & then non-meridianal
tipping, hadn’t occurred to me.
…to directly read the Local True Solar Time
The public stationary sundial in my town is mounted normally for Local True
Solar Time. It’s correction-plaque gives un-adjusted EqT, with an
instruction to add a certain number of minutes for the longitude-correction.
On Sun, Apr 2, 2023 at 17:26 Steve Lelievre
wrote:
> You don’t need two
On Tue, Apr 4, 2023 at 08:45 wrote:
> Rotating the dial plate around a vertical axis is wrong because the hours
> lines are not at constant angles.
>
> Rotating the whole dial around the polar axis is the correct way to adjust
> a local solar time dial to a different longitude, the time zone
Rotating the dial plate around a vertical axis is wrong because the
hours lines are not at constant angles.
Rotating the whole dial around the polar axis is the correct way to
adjust a local solar time dial to a different longitude, the time zone
center, for example.
Having a dial show the
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I think I must be missing something here. I cannot
Hi Steve,
I use to be a member of the NASS but I am retired now. And due to funds
I was not able to renew my membership. So I don't have access to Fred
Sawyer's and Bill Gottesman's article.
Maybe the Article and the drawing of the Earth with sundials could be
used to explain this?
Hi all,
Is the Sundial Mailing list able to accept images?
Below is how we can understand how sundials work. A sundial is a
mechanical clock. Sundials are geared to the largest clock in the world,
Earth. Look at it from a mechanical point of view on a spinning Earth.
Draw the earth and cut
Hi all,
This link I think is a good way of showing. How we can understand how
sundials work. A sundial is a mechanical clock. Sundials are geared to
the largest clock in the world, Earth. Look at it from a mechanical
point of view on a spinning Earth.
Draw the earth and cut out paper
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