I mentioned several alignments, the correction of any one of which could be
used to determine how much the dial-plate should be rotated in its own
plane (either before or after the tip).
Most recently I suggested the altitude of the pointing-direction of the
style.
But it seems to me that it
I retract the addendum. I wrote it with the notion that the noon-line
should be under the style. …as if the dial were intended to read for its
own longitude.
So, sorry—disregard the addendum (…as you probably already have).
The dial-plate’s rotation in its own plane should be to correct the
For complete generality:
If your sundial was made for a latitude greater then yours by an amount
called “DeltaLat” (which could be positive or negative), & if you want the
dial to give LTST for a longitude 7 degrees west of yours (maybe because
that’s your standard-meridian), then:
After the
Yes, I spoke of a special-case in which you’re 7 degrees east of your
standard-meridian. …for a concrete example. But the rest of what I said was
for the general-case in which you want the dial to read in the LTST at your
standard-meridian.
But yes, I didn’t speak of when the dial is made for a
On 2023-04-08 8:52 p.m., Michael Ossipoff wrote:
I know you said you wanted a link, not instructions, but people have
been suggesting how to achieve dial-autocorrection to Local True Solar
Time (LTST) at the standard-meridian, instead of one’s own meridian.
So I felt that it would be
Addendum:
…
Instead of finding the dial-plate rotation in its own plane that corrects
the style’s pointing-direction, it might be easier to, instead, find the
dial-plate rotation in its own plane that puts the dial’s noon-line in the
meridianal-plane….i.e. gives that noon-line an azimuth of
Steve—
…
I know you said you wanted a link, not instructions, but people have been
suggesting how to achieve dial-autocorrection to Local True Solar Time
(LTST) at the standard-meridian, instead of one’s own meridian. So I felt
that it would be justified to comment about it.
…
…even though
Contrary to what I suggested yesterday, the adjustment of a sundial to
give LTST at the standard-meridian doesn’t require solution of a system of
equations. It’s a straightforward coordinate-transformation:
…
Say the dial-plate is circular. For a sphere that circumscribes that
dial-plate, the
[quote]
Assuming that a dial should read only local solar time is a rather limited
view.
[/quote]
…
:-) What?
…
So, an expressed preference is a “limited view”? :-)
…
LTST stands for Local-True-Solar-Time.
…
A dial that reads in LTST at your latitude *at your standard
meridian*…instead
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
nes 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
>> *On Behalf Of *Steve Lelievre
&
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
its polar axis.
Jack Aubert
From: sundial On Behalf Of Steve Lelievre
Sent: Monday, April 3, 2023 7:47 PM
To: Rod Wall ; kool...@dickkoolish.com
Cc: 'Sundial sundiallist'
Subject: Re: Adjusting dial to new location
Hi, Roderick,
My home internet connection is still non
uni-koeln.de> *On Behalf Of *Steve Lelievre
*Sent:* Sunday, April 2, 2023 5:16 PM
*To:* Michael Ossipoff
<mailto:email9648...@gmail.com>
*Cc:* Sundial List
<mailto:sundial@uni-koeln.de>
*Subject:* Re: Adjusting dial to new location
Michael,
Yes, I rec
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
That surprises me too. I’d have expected that the only differences would be
that the dial is numbered counterclockwise, & that north & & south are
replaced with poleward & equatorward.
On Mon, Apr 3, 2023 at 16:47 Steve Lelievre
wrote:
> Hi, Roderick,
>
> My home internet connection is still
Hi, Roderick,
My home internet connection is still non-functional so I can't fix it
yet, but it does seem that I will have to add an extra test to handle
southern hemisphere locations and reducing latitudes. Actually, I
originally had a southern hemisphere check in there but took it out
-- Forwarded message -
From:
Date: Mon, Apr 3, 2023 at 07:35
Subject: Re: Adjusting dial to new location
To: Michael Ossipoff
Local Solar Time is one of the things that a dial can do. But I might want
Time Zone time. Or I might want Paris France time. A dial can do both
-- Forwarded message -
From: Michael Ossipoff
Date: Mon, Apr 3, 2023 at 14:12
Subject: Re: Adjusting dial to new location
To:
Of course, but I’d always make the dial to directly show Local True Solar
Time. I’d never incorporate a built-in longitude correction.
My use of EqT
-- Forwarded message -
From: Michael Ossipoff
Date: Mon, Apr 3, 2023 at 14:04
Subject: Re: Adjusting dial to new location
To: Rod Wall
Yes, because you’ve moved the dial south, you tip it south.
The wedge-use is as you say, but I’d prefer a flat, vertical-edge shim,
because
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 On Behalf Of Steve Lelievre
Sent: Sunday, April 2, 2023 5:16 PM
To: Michael Ossipoff
Cc: Sundial List
Subject: Re: Adjusting dial to new
Hi Steve,
For both examples below with all sundials at the same Longitude. The
instructions indicate:
Place the wedge-sundial assembly on a horizontal surface in a nice sunny
location. *Start with the higher end of the wedge to the north* and the
sides aligned on a north-south line and the
se? It sounds like a good project for a 3-D printer.
>
>
>
> Jack
>
>
>
> *From:* sundial
> *On Behalf Of *Steve Lelievre
> *Sent:* Sunday, April 2, 2023 5:16 PM
> *To:* Michael Ossipoff
> *Cc:* Sundial List
> *Subject:* Re: Adjusting dial to new location
>
Ossipoff
Cc: Sundial List
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
*From:* sundial
> *On Behalf Of *Steve Lelievre
> *Sent:* Sunday, April 2, 2023 5:16 PM
> *To:* Michael Ossipoff
> *Cc:* Sundial List
> *Subject:* Re: Adjusting dial to new location
>
>
>
> Michael,
>
> Yes, I recognize that to get Mean Time involves
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 *On Behalf Of *Steve
Lelievre
*Sent:* Sunday, April 2, 2023 5:16 PM
*To:* Michael Ossipoff
*Cc:* Sundial List
*Subject:* Re: Adjusting dial to new
*Sent:* Sunday, April 2, 2023 5:16 PM
*To:* Michael Ossipoff
*Cc:* Sundial List
*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
to the origin of the gnomon.
Does this make sense? It sounds like a good project for a 3-D printer.
Jack
From: sundial On Behalf Of Steve Lelievre
Sent: Sunday, April 2, 2023 5:16 PM
To: Michael Ossipoff
Cc: Sundial List
Subject: Re: Adjusting dial to new location
Michael,
Yes, I
...& thank you for doing so, because online calculators & dial-printing
programs make sundials readily accessible to everyone.
On Sun, Apr 2, 2023 at 5:15 PM Steve Lelievre <
steve.lelievre.can...@gmail.com> wrote:
> Michael,
>
> Yes, I recognize that to get Mean Time involves Equation of Time
>
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
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,
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
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