Re: sundial Digest, Vol 215, Issue 2

[Bill Gottesman]

My guess on this one (without using mirrors):
Point the  bottom of an empty can at the sun.  The shadow inside the can
now points in the direction of the sun, though the definition of "in the
direction of the sun" in this case is debatable.
-Bill

On Mon, Mar 11, 2024 at 9:33 AM Chris Lusby Taylor 
wrote:

> This reader has so far failed to see how a shadow can be in the same
> direction as the light source, if by that Frank means that it is between
> the object and the light. Perhaps Frank will enlighten us at next month's
> annual British Sundial Society Conference.
>
>>
>> Date: Mon, 11 Mar 2024 09:01:46 +
>> From: Frank King 
>> Of course, a shadow CAN be in the same direcion as the light.  I'll leave
>> that as an exercise for the reader :-)
>>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Substitute for DeltaCad?

[Bill Gottesman]

Hello All,

DeltaCad does not function fully on my Mac M1Pro (Mac silicon based).  It
will not save in .dxf format, so I can't move things out of the .dc
proprietary DeltaCad files into Adobe Illustrator.
DeltaCad has been discontinued by the developer.
Does anyone have a work-around, or a different simple-to-use 2-D CAD
program to recommend?  I really like DeltaCad but I don't see how to get
around this.

Best,
Bill Gottesman
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Difference between types of equinox

[Bill Gottesman]

I seem to recall Fred contributing to a similar conversation a few years
ago.  Speaking from ignorance, I think the sun will not be at exactly 0
declination at 180 longitude because the moon can pull the earth above or
below the ecliptic depending on the lunar orbit. I think the effect is
tiny, and only affects the timing of the zero degree declination definition
of equinox by maybe a minute?

Here is a paste from wikipedia:
The modern definition of equinox is the instant when the Sun's apparent
geocentric ecliptic longitude is 0° (northward equinox
) or 180° (southward equinox
).[34]
[35]
[36]
 Note that at that
moment, its latitude will not be exactly zero, since Earth is not exactly
in the plane of the ecliptic. Its declination will also not be exactly
zero, so the scientific definition is slightly different from the
traditional one. The *mean* ecliptic is defined by the barycenter
 of Earth and the Moon combined,
to minimize the fact that the orbital inclination of the Moon causes the
Earth to wander slightly above and below the ecliptic.[38]


Oops, I did not answer your question, which was about the time intervals,
not the cause.  Sounds like a job for good astronomy modeling software -
maybe Stellarium?

-Bill

On Mon, Sep 4, 2023 at 7:25 PM Steve Lelievre <
steve.lelievre.can...@gmail.com> wrote:

> Hello,
>
>  From what I've read recently, there are three variants of an equinox:
>
> - Modern astronomical definition: apparent geocentric longitude of the
> sun is 0 or 180 degrees.
>
> - The older astronomical definition (often used in dialling) : solar
> declination is 0 degrees.
>
> - 'Temporal equinox': halfway between solstices as measured by passage
> of time, which is the lay/folk/traditional understanding
>
> I'd like to know:
>
> How big are the time intervals between these three types of equinoxes?
>
> How much do these intervals change as the years or centuries go by, if
> at all?
>
> Thanks,
>
> Steve
>
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Comments on Peter's mail

[Bill Gottesman]

Hello Valentin,

My version of DeltaCad (10.0.0 for Mac) will not run .bas macros, only
.scpt macros.
Do you know if there is a way to get your macros to run on this version of
deltacad?

-Best, Bill

On Mon, Oct 31, 2022 at 4:32 AM Valentin Hristov 
wrote:

> Greetings from Bulgaria to the sundial community!
> Thank you, Peter, for mentioning my DeltaCad macro
> www.math.bas.bg/complan/valhrist/az-ht.bas
> I give here only the link since usually the servers reject files with
> extension .bas. You have to open them in a new page, mark the whole text,
> copy to the clipboard, and paste into some text editor, saving the file
> with extension .bas. Then run DeltaCad - Macro - RunMacro - choose the
> saved file *.bas.
> Unfortunately, my polar variant is only horizontal (azimuth and height),
> but can be used as an effective sundial as shown on the attached picture.
> The edge of a tea bags box is the vertical gnomon!
> Many of my DeltaCad macros can be found on my page
> My Stuff - Valentin Hristov (bas.bg)
> 
> as well with many details on Carl Sabanski's page
> The Sundial Primer - DeltaCad Sundial Macros - Valentin Hristov - Polar
> Box Sundial (mysundial.ca)
> 
> Let there be more sunshine on your sundials!
> Valentin Hristov
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Paris sundial

[Bill Gottesman]

Is this real or a concept? The shadows don’t move in the rest of the image.
- Bill

On Sun, Oct 30, 2022 at 7:14 AM Alexei Pace  wrote:

> Interesting one in Rue Montmartre
> https://www.instagram.com/reel/Cj0hS2JIPQV/?igshid=YmMyMTA2M2Y=
>
> On Wed, Oct 26, 2022, 11:58 Werner Riegler  wrote:
>
>> Dear John,
>>
>> I know this object as “Horizontoscope".
>> http://www.horizontoscop.com/eng/index_eng.html
>>
>> I bought one recently after reading about it in one of Helmut
>> Sonderegger’s articles, where he gives the math of it.
>>
>> https://www.herzog-forsttechnik.ch/wp-content/uploads/2022/08/Sonnenkompass_Flyer-2022.pdf
>>
>> It’s quite interesting how the hyperbolic surface makes the image
>> independent of the height between the observing eye and the device.
>>
>> There is a german wikipedia entry.
>> https://de.wikipedia.org/wiki/Horizontoskop
>>
>> Maybe someone from the sundial list can produce an english entry with the
>> theory. It’s a nice device !
>>
>> best regards
>> Werner
>>
>>
>>
>>
>>
>> On 26 Oct 2022, at 02:45, John Pickard  wrote:
>>
>> Good morning,
>>
>> Has anyone come across this dial-related device?
>>
>>
>> https://picclick.co.uk/ARCHITECT-TOOL-Window-SUNLIGHT-SUN-ELEVATION-Enraf-144741549298.html
>>
>> Cheers, John.
>>
>> Dr John Pickard.
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Computing hour lines for horizontal sundials

[Bill Gottesman]

I'm pretty sure that for excel, you would need to enter

=LOG(TAN(RADIANS(7)))

because the trig functions in excel work on radians rather than degrees.
-Bill

On Tue, Aug 9, 2022 at 1:50 AM Bryan Mumford  wrote:

> I’m working from Albert Waugh’s book “Sun dials, Their Theory and
> Construction”. On page 45 he presents a method for computing hour lines. I
> lack significant math skills, but I know how to work Excel. I don’t
> understand how he is calculating these values.
>
> He says, for example, that “log tan t” of 7°30’ is 9.11943.
>
> In my simple-minded way I asked Excel to show me log(tan(7)) and got a
> very different value.
> I tried converting 7°30’ to radians and that didn’t get any closer.
>
> How can I calculate "log tan t" or "log sin latitude” with Excel to get
> the values he shows?
>
> I anticipate further problems with the last two columns, but you have to
> start somewhere….
>
> - Bryan
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: What's the inner scale on this photo for?

[Bill Gottesman]

Or the slot near one end of the adelaide is just to guide the adelaide as
it slides back and forth in the internal geared mechanism.
Clearly a vertical gnomon had to be present on some part of the adelaide.
I think Steve is on the right track.
In terms of the screws or pins blocking movement of the adelaide, I think
the whole center section (curcular brass plates) pivots along with the
adelaide, so that is moot.

-Bill again.

On Fri, Oct 29, 2021 at 9:24 PM Bill Gottesman 
wrote:

> My two cents:
> I have a different guess about the round dial with the indicator.  My
> guess is that it is a calendar of months, and that turning the indicator to
> the correct month adjusts the length of the adelaide to the correct
> distance for reading time on the azimuth dial.  I do not know what casts
> the shadow, but I will guess that Sara is correct, that the slot holds a
> vertical vane.
>
> Being an azimuth dial, the correct declination scale must be used.  I see
> the circular declination lines, but they are not named.  So I think the
> pointer of the adelaide is set to the correct circle radius (correct
> length) by turning the indicator.
>
> -Bill
>
> On Fri, Oct 29, 2021 at 6:04 PM Steve Lelievre <
> steve.lelievre.can...@gmail.com> wrote:
>
>> Thank you, Sara and Patrick for your replies to my question.
>>
>> I shall try to get to the Science Museum sometime to have a look at the
>> dial, if that can be arranged.
>>
>> I’ve been trying to figure out how the cam that Sara mentioned might work.
>>
>> I’ve never studied the working of cams and this case isn’t obvious to me
>> as there are two inputs, azimuth and declination, that must drive the
>> minutes shown.
>>
>> If anyone can send me an explanation or drawing, it would me much
>> appreciated.
>>
>> Steve
>>
>> On Mon, Oct 25, 2021 at 19:19, Schechner, Sara 
>> wrote:
>>
>>> Hi Steve,
>>> The photo of the azimuth dial is hard to read.  I don't know what screws
>>> you are talking about preventing the arm from turning.  The arm is
>>> backwards at the moment since the pointed end should be on the scale of
>>> hour lines.  I am not convinced that there is a flap on the square end of
>>> the arm for a vane.  The sun at most angles would not fall far along the
>>> arm to reach the other end where the slot is.  Rather, I suspect there was
>>> a vertical gnomon in the slot at the pointed end.  Its shadow could have
>>> been aligned with the point so that the point was in line with the sun's
>>> azimuth.  As for the round dial, it almost always shows minutes and is
>>> geared to the rotation of the arm.
>>>
>>> That's my best guess.
>>> Sara
>>>
>>> -Original Message-
>>> From: sundial  On Behalf Of Steve Lelievre
>>> Sent: Monday, October 25, 2021 1:22 PM
>>> To: Sundial List 
>>> Subject: What's the inner scale on this photo for?
>>>
>>> Hi,
>>>
>>> Today a website called Vermont Free Press published an appallingly
>>> confusing (to me) summary of types of sundials. If you can bear to look,
>>> it's at https://www.vermontpressbureau.com/types-of-sundials/
>>>
>>> However, there was one thing about it that piqued my interest: the photo
>>> of an azimuth sundial (
>>> https://www.vermontpressbureau.com/wp-content/uploads/2021/10/Azimuthal.jpg
>>> ).
>>>
>>>  From what I can make out, there is a metal flap at the end of the
>>> alidade / sighting arm (the end at top in the photo). It must get turned up
>>> to make a shadow-caster.  I guess the arm has to be rotated so that the
>>> shadow falls along it, and time is then read from where the right-hand edge
>>> of the arm crosses the net of hour and declination lines. But then,
>>> wouldn't the screws seen in the upper plate block the arm from being turned
>>> to the required orientation?
>>>
>>> Another bit I can't figure is the little circular scale just north of
>>> the centre of the dial, with the pointer. Perhaps just an Equation of Time
>>> scale? Or perhaps a cam connects it to the arm so that it can be used to
>>> set the arm's length? (The slot in the arm suggests it can be slid in and
>>> out to set the tip at the applicable declination circle, which is a nifty
>>> feature.)
>>>
>>> Cheers,
>>>
>>> Steve
>>>
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>>
>>> --
>> Cell +1 778 837 5771
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: What's the inner scale on this photo for?

[Bill Gottesman]

My two cents:
I have a different guess about the round dial with the indicator.  My guess
is that it is a calendar of months, and that turning the indicator to the
correct month adjusts the length of the adelaide to the correct distance
for reading time on the azimuth dial.  I do not know what casts the shadow,
but I will guess that Sara is correct, that the slot holds a vertical vane.

Being an azimuth dial, the correct declination scale must be used.  I see
the circular declination lines, but they are not named.  So I think the
pointer of the adelaide is set to the correct circle radius (correct
length) by turning the indicator.

-Bill

On Fri, Oct 29, 2021 at 6:04 PM Steve Lelievre <
steve.lelievre.can...@gmail.com> wrote:

> Thank you, Sara and Patrick for your replies to my question.
>
> I shall try to get to the Science Museum sometime to have a look at the
> dial, if that can be arranged.
>
> I’ve been trying to figure out how the cam that Sara mentioned might work.
>
> I’ve never studied the working of cams and this case isn’t obvious to me
> as there are two inputs, azimuth and declination, that must drive the
> minutes shown.
>
> If anyone can send me an explanation or drawing, it would me much
> appreciated.
>
> Steve
>
> On Mon, Oct 25, 2021 at 19:19, Schechner, Sara 
> wrote:
>
>> Hi Steve,
>> The photo of the azimuth dial is hard to read.  I don't know what screws
>> you are talking about preventing the arm from turning.  The arm is
>> backwards at the moment since the pointed end should be on the scale of
>> hour lines.  I am not convinced that there is a flap on the square end of
>> the arm for a vane.  The sun at most angles would not fall far along the
>> arm to reach the other end where the slot is.  Rather, I suspect there was
>> a vertical gnomon in the slot at the pointed end.  Its shadow could have
>> been aligned with the point so that the point was in line with the sun's
>> azimuth.  As for the round dial, it almost always shows minutes and is
>> geared to the rotation of the arm.
>>
>> That's my best guess.
>> Sara
>>
>> -Original Message-
>> From: sundial  On Behalf Of Steve Lelievre
>> Sent: Monday, October 25, 2021 1:22 PM
>> To: Sundial List 
>> Subject: What's the inner scale on this photo for?
>>
>> Hi,
>>
>> Today a website called Vermont Free Press published an appallingly
>> confusing (to me) summary of types of sundials. If you can bear to look,
>> it's at https://www.vermontpressbureau.com/types-of-sundials/
>>
>> However, there was one thing about it that piqued my interest: the photo
>> of an azimuth sundial (
>> https://www.vermontpressbureau.com/wp-content/uploads/2021/10/Azimuthal.jpg
>> ).
>>
>>  From what I can make out, there is a metal flap at the end of the
>> alidade / sighting arm (the end at top in the photo). It must get turned up
>> to make a shadow-caster.  I guess the arm has to be rotated so that the
>> shadow falls along it, and time is then read from where the right-hand edge
>> of the arm crosses the net of hour and declination lines. But then,
>> wouldn't the screws seen in the upper plate block the arm from being turned
>> to the required orientation?
>>
>> Another bit I can't figure is the little circular scale just north of the
>> centre of the dial, with the pointer. Perhaps just an Equation of Time
>> scale? Or perhaps a cam connects it to the arm so that it can be used to
>> set the arm's length? (The slot in the arm suggests it can be slid in and
>> out to set the tip at the applicable declination circle, which is a nifty
>> feature.)
>>
>> Cheers,
>>
>> Steve
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>> --
> Cell +1 778 837 5771
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Is this an educational sundial, or a 'NON-dial'?

[Bill Gottesman]

I should add, it would be an extremely confusing way to teach sundials, and
I would not recommend this dial from a teaching standpoint.
-Bill

On Sat, Apr 3, 2021 at 3:13 PM Bill Gottesman 
wrote:

> There is a much more detailed image of the mutli-purpose dial if you "look
> inside" the book sample at
> https://www.amazon.com/Time-Flies-Really-stands-still/dp/1977072658.
>
> This would not function as a common horizontal sundial (except at the
> north or south pole).  If it were properly tilted and oriented at your
> latitude to function as an equatorial sundial, then it could work.  You
> would still have to manually rotate the backward-appearing gnomon to cast
> its narrowest shadow.  It is unclear from the limited sample of the book if
> that is how the author intended the dial to be set up.
>
> -Bill
>
>
> On Sat, Apr 3, 2021 at 2:14 PM Linda Reid 
> wrote:
>
>>
>> Has any member of the List ever come across this book - and (if so),
>> could you seriously recommend it as an educational item for schools?
>>
>> The title of it is "Time Flies - Really? Prove it!", from the author
>> Brian Macfarlane.  The ISBN number is 978-1977085498, which contains
>> about 160 pages and is available via "Amazon" for around Five Pounds.
>>
>> Attached is a very small JPEG image, illustrating its 'front cover'.
>>
>>
>> Apparently, it describes the use of his 'Multi-purpose Sundial' plus
>> is aimed at schools as being a curriculum-wide project - but looking
>> at the illustration on the front cover, it seems to be a 'NON-dial'!
>>
>> In a private Email to myself, the author claims it has been endorsed
>> by Sir Anthony Seldon (Vice-Chancellor of "Buckingham University"),
>> who seemingly has described it as being 'a good idea for schools'.
>>
>> As a teacher, I would prefer to have some independent opinions from
>> sundial 'experts' - before considering its use for my own school, as
>> this could be a "total waste of money" with no 'educational value'.
>>
>>
>> I look forward to any information - either to the List, or privately.
>>
>> Sincerely, Linda Reid.
>>
>>
>> --
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Is this an educational sundial, or a 'NON-dial'?

[Bill Gottesman]

There is a much more detailed image of the mutli-purpose dial if you "look
inside" the book sample at
https://www.amazon.com/Time-Flies-Really-stands-still/dp/1977072658.

This would not function as a common horizontal sundial (except at the north
or south pole).  If it were properly tilted and oriented at your latitude
to function as an equatorial sundial, then it could work.  You would still
have to manually rotate the backward-appearing gnomon to cast its narrowest
shadow.  It is unclear from the limited sample of the book if that is how
the author intended the dial to be set up.

-Bill


On Sat, Apr 3, 2021 at 2:14 PM Linda Reid 
wrote:

>
> Has any member of the List ever come across this book - and (if so),
> could you seriously recommend it as an educational item for schools?
>
> The title of it is "Time Flies - Really? Prove it!", from the author
> Brian Macfarlane.  The ISBN number is 978-1977085498, which contains
> about 160 pages and is available via "Amazon" for around Five Pounds.
>
> Attached is a very small JPEG image, illustrating its 'front cover'.
>
>
> Apparently, it describes the use of his 'Multi-purpose Sundial' plus
> is aimed at schools as being a curriculum-wide project - but looking
> at the illustration on the front cover, it seems to be a 'NON-dial'!
>
> In a private Email to myself, the author claims it has been endorsed
> by Sir Anthony Seldon (Vice-Chancellor of "Buckingham University"),
> who seemingly has described it as being 'a good idea for schools'.
>
> As a teacher, I would prefer to have some independent opinions from
> sundial 'experts' - before considering its use for my own school, as
> this could be a "total waste of money" with no 'educational value'.
>
>
> I look forward to any information - either to the List, or privately.
>
> Sincerely, Linda Reid.
>
>
> --
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Aequinox

[Bill Gottesman]

It's always nice when things work like you hope they will.  Fun photo -Bill

On Tue, Sep 24, 2019 at 2:07 PM  wrote:

> Hi All,
>
> We also celebrated Equinox in Wroclaw, Poland with a newly built noon mark
> dial - following the original, Leicester "Eye of Time" pattern by professor
> Allan Mills.
> Please find a picture taken shortly before noon below:
>
> https://we.tl/t-xvRNWbuE8K
>
> While the solar noon was some two hours after Equinox, the declination
> difference was still so small (ca. 1/20 degree) that Sun's image passed
> almost ideally through the Equinox point.
> So at a noon moment we obseved a kind of annular eclipse !
>
> It was a great fun to observe with it Equinox with the public and the
> first equinox for this dial, as we set it by summer solstice !
>
> Regards,
>
> Maciek Lose
>
>
>
>
>
> Od: "Brad Thayer via sundial" 
> Do: sundial@uni-koeln.de;
> Wysłane: 14:42 Wtorek 2019-09-24
> Temat:
>
> > Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
> > eigentliche Nachricht steht dadurch in einem Anhang.
> >
> > This message was wrapped to be DMARC compliant. The actual message
> > text is therefore in an attachment.
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Strange analemmatic sundial - how does it work?

[Bill Gottesman]

Hello Steve, I'll take a guess at this.
I think the dial is really a heliochronometer with an analemma, not an
analemmatic dial.  I think the screws up top held a focusing lens or a
pinhole aperture that projected a beam on to an analemma on to the lower
plate.  The analemma is not visible in that picture.  The dial is turned to
make the beam align, so the hours go counter-clockwise, and the time is
read across from stationary indicator at the very top of the dial, hidden
from view in this photo.
Similar to the upper left dial seen at
https://equation-of-time.info/sundials-with-shaped-alidades .  -Bill
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Wheatstone's polarizing sundial

[Bill Gottesman]

I agree, I cannot make sense of the dial described by Frans.  The article
Patrick links does not describe this particular arrangement of hour lines.
Looking closely at the image, it seems that all of the odd numbered hours
are labeled on the same large sheet of material (this material may or
may-not be polarizing).  The even numbered hours each have their own sliver
of material, and are spaced 15 degrees apart like hours on an equatorial
dial. * It is possible that the dial is properly constructed, but
improperly labeled.*  I think a correct labelling would be if each of the
even-numbered strips had been labeled consecutively (from 6:00AM to 6:00 PM
for the semicircle).

-Bill Gottesman

On Tue, May 21, 2019 at 7:00 PM Patrick Vyvyan 
wrote:

> Wheatstone's Polarizing Dial
>
> An explanation of Wheatstone's invention is to be found in the Report of
> the meeting of the British Association for the Advancement of Science in
> Swansea held in 1848, although to be honest it's scientific foundation has
> me a little challenged! The report is available online at
> https://www.biodiversitylibrary.org/item/46637#page/188/mode/1up
> Should you have access to an original paper copy, the description of the
> Polarizing Dial begins on page 10. The numeral scale represents one
> complete day of 24 hours - it seems the device can work even without direct
> sunlight.
>
> Best wishes,
> Patrick Vyvyan
>
>
>
> On Tue, 21 May 2019 at 16:07, Maes, F.W.  wrote:
>
>> Recently the Tesseract Catalogue 109 was announced on this list. Item nr.
>> 13 is a polarizing sundial by Charles Wheatstone. A virtually identical
>> dial is in the collection of the Greenwich museums, see:
>> https://collections.rmg.co.uk/collections/objects/265579.html.
>> I have never understood how this sundial works. The hour scale shows 2 x
>> 12 hour numbers in a semicircle. So whatever pattern is observed in the
>> black glass reflector, it is obviously supposed to rotate over 180° in 24
>> hours, which is half the angular velocity of the sun itself. How does this
>> frequency division-by-two come out? Can anybody explain?
>>
>> Thanks!
>> Frans Maes
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Any idea of what these stone circles in a South wall could be?

[Bill Gottesman]

Link to photos did not work.  Please check link.  -Bill

On Thu, Jan 10, 2019 at 6:29 AM Azucena Hernandez <
azucena.hernandezpe...@gmail.com> wrote:

> Dear all,
>
> This is my first message to this mailing list and I do it under the
> suggestion of John Davis from the UK. My filed of research within the
> University Complutense of Madrid is astrolabes in al-Andalus and Medieval
> Spain and my knowledge on sundials is not that high.
> The reason of this message is to ask you about the four stone circles
> attached to the upper part of the South wall of the South Transept of the
> Salamanca Old Cathedral (12th century). Detailed photographs taken from the
> roof of the cathedral are available in:
>
>
> https://www.dropbox.com/home/Salamanca%20Cathedral%20stone%20circles%20in%20South%20wall
>
> The stone circles seem to have been located there in purpose and possible
> reasons like holding coat of arms or any other kind of sculpture have been
> discharged for various reasons. This South wall is only visible from the
> cloister. Our first idea was to be a kind of sundial but completely
> different from the many medieval sundials engraved in south walls of
> cathedrals or other buildings in Spain with their well known layout of
> engraved hour lines.
> Have you seen anything similar? Any idea from your side will be more than
> welcomed.
>
> Best regards,
> Azucena
> [image: LOGO UCM oficial.png]
>
> Dra. Azucena Hernández Pérez
>
> Universidad Complutense de Madrid
>
> *https://www.ucm.es/historiadelarte/azucena-hernandez-perez
> *
>
> *https://ucm.academia.edu/AzucenaHernandez
> *
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Gnomon Gap Puzzle

[Bill Gottesman]

Hello Frank,

Could the space be a north-south alley, street, or park between two
buildings?  The vertical sides of the buildings adjoining the space can be
seen as two vertical gnomons for an azimuthal dial.  You would lay out the
morning hours to the west of the eastern building, and the afternoon hours
to the east of the western building.  You could scale the dials so the two
halves touch in the center, or whatever arrangement that looks attractive.

-Bill

On Wed, Jan 2, 2019 at 3:44 AM Frank King  wrote:

> Dear Maciej and Sara,
>
> Gosh.  Those are really incredible dials.
> The Nested L-shapes of the chapter rings
> on the Jacques Le Marie dial are very
> cleverly set out.  I wonder how big a
> market there was for this kind of dial!
>
> Maciej's description of a Nuremberg
> Diptych - The shadow was cast by the
> edges of the upper leaf of the dial -
> is quite close to what I have in mind.
>
> This would be fine in British Latitudes
> but as you move nearer to the equator
> you find yourself having to peer inside
> an ever-narrowing gap!
>
> Very best wishes
>
> Frank
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Equinox Analemma

[Bill Gottesman]

I feel better now.  -Bill

On Sun, Sep 23, 2018 at 1:02 PM Steve Lelievre <
steve.lelievre.can...@gmail.com> wrote:

> Bill,
>
> NASA has corrected the page since your post. Now it says "The featured
> analemma was composed from images taken every few days at noon".
>
> Steve
>
>
> On 2018-09-23 7:58 AM, Bill Gottesman wrote:
>
> The NASA page says the photos were taken at 4PM, but it sure looks like
> they were taken at mean solar noon (because the analemma is vertical).
> Does anyone have an explanation for this?
>
> -Bill
>
> On Sun, Sep 23, 2018 at 10:38 AM Robert Terwilliger 
> wrote:
>
>> Astronomy Picture of the Day
>>
>>
>>
>> https://apod.nasa.gov/apod/ap180923.html
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>
> ---https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Equinox Analemma

[Bill Gottesman]

The NASA page says the photos were taken at 4PM, but it sure looks like
they were taken at mean solar noon (because the analemma is vertical).
Does anyone have an explanation for this?

-Bill

On Sun, Sep 23, 2018 at 10:38 AM Robert Terwilliger 
wrote:

> Astronomy Picture of the Day
>
>
>
> https://apod.nasa.gov/apod/ap180923.html
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Summer Solstice in Florence

[Bill Gottesman]

Hello Claus,

Yes, in J. L. Heilbron's "The Sun in the Church" he reports that Toscanelli
designed the original meridian and solstice mark in 1510, placing a bronze
plaque at the sun's noon solstice image.  Around 1754 Leonardo Ximenes
discovered that Toscanelli's 1510 meridian was off by almost a full
degree.  The I remain confused regarding the two circles (elipses), as the
smaller circle is clearly north of the center of the larger circle.

Heilbron offers clues to the answer, but not a complete explanation: One is
that the original gnomon hole was created around 1475, and was "reset" in
1511, the year after the the brass marker was placed.  I do not know if
that means the gnomon hole was moved, or by how much.  Furthermore, I do
not see a brass marker, so this is confusing.  I think both of the circles
are stone, based on the video and other photos.  From 1510 to 1754 the
ecliptic tilt shrank about .03 degrees, which would have moved the center
of the solstice mark northward about 4.5 centimeters (my calculation).  The
smaller circle/ellipse is displaced northward from the lager ellipse, but
to me it looks like a distance much greater than 4.5 cm.  So I am stumped
here.  -Bill

On Thu, Jun 7, 2018 at 5:18 PM, Claus Jensen  wrote:

> The divided line or band to the left in the picture is Leonardo Ximenes’
> so-called *new* meridian line described in his 1757 book *Del vecchio e
> nuovo gnomone fiorentino*
> . It
> deviates slightly from the *old *meridian line, dating from ca. 1475, due
> to Paolo Toscanelli. The two circles are what remains of Toscanelli’s
> meridian line.
>
> According to a sketch in Ximenes’ book, the smaller circle is called *The
> solstice marble*. The greater circle contains a date, hardly visible
> today, given in the old roman calendar, corresponding to 12 June 1510 in
> the Julian calendar. Thus summer solstice in 1510 took place on 12 June.
>
>
> Claus Jensen, DK
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Summer Solstice in Florence

[Bill Gottesman]

On Thu, Jun 7, 2018 at 3:19 PM, Willy Leenders 
wrote:

> Hi Bill,
>
> My answers on your questions are:
>
> 1.
> The light spot moves from the west to the east and the camera observes
> this from a position north of that displacement.
>
I agree. -Bill

>
> 2.
> The image of a circle projected by the sun is only a circle in an
> exceptional case. In all other cases it is an ellipse.
>
Yes, but in this case the ellipse appears elongated east-west, but it
should be elongated north-south.  I am guessing the low camera angle has
created this illusion of east-west elongation. -Bill

>
> 3.
> The inner circle indicates the right place, the outer circumference
> corresponds to the circumference of the light spot on that moment
>
Not sure I understand this.  -Bill

>
> Willy Leenders
> Hasselt in Flanders (Belgium)
>
> Visit my website about the sundials in the province of Limburg (Flanders)
> with a section 'worth knowing about sundials' (mostly in Dutch):
> http://www.wijzerweb.be
>
>
>
>
> Op 7-jun-2018, om 19:51 heeft Bill Gottesman het volgende geschreven:
>
> Thought provoking video.  Here are a two simple questions worth
> contemplating:
>
> 1.  From what perspective is the video filmed?Is the camera roughly south,
> north, east,or west of the summer solstice mark?
>
> 2.  Why does the sun appear elongated in its right-to-left direction of
> travel across the screen?  Is this at all surprising?
>
> And a hard one, the answer to which I am unsure:
> 3.  What is the purpose of constructing the smaller circle (or ellipse)
> inside of the larger one?
>
> -Bill
>
> On Thu, Jun 7, 2018 at 7:38 AM, J. Tallman  com> wrote:
>
>> Hello All,
>>
>> This morning I saw an article online about the upcoming summer solstice
>> that may be of interest:
>>
>> https://www.thelocal.it/20180606/florence-duomo-gnomon-summer-solstice
>>
>> Get your sundial prototypes ready to test, it won't be long before the
>> special moment comes!
>>
>>
>> Best,
>>
>> Jim Tallman
>> <http://www.spectrasundial.com/>www.spectrasundial.com
>> <http://www.artisanindustrials.com/>www.artisanindustrials.com
>>
>> jtall...@artisanindustrials.com
>> 513-253-5497
>>
>> This message is being sent remotely as I am currently out of the studio.
>> Please excuse any further delay in response.
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> Willy Leenders
> Hasselt in Flanders (Belgium)
>
> Visit my website about the sundials in the province of Limburg (Flanders)
> with a section 'worth knowing about sundials' (mostly in Dutch):
> http://www.wijzerweb.be
>
>
>
>
>
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Summer Solstice in Florence

[Bill Gottesman]

Thought provoking video.  Here are a two simple questions worth
contemplating:

1.  From what perspective is the video filmed?Is the camera roughly south,
north, east,or west of the summer solstice mark?

2.  Why does the sun appear elongated in its right-to-left direction of
travel across the screen?  Is this at all surprising?

And a hard one, the answer to which I am unsure:
3.  What is the purpose of constructing the smaller circle (or ellipse)
inside of the larger one?

-Bill

On Thu, Jun 7, 2018 at 7:38 AM, J. Tallman 
wrote:

> Hello All,
>
> This morning I saw an article online about the upcoming summer solstice
> that may be of interest:
>
> https://www.thelocal.it/20180606/florence-duomo-gnomon-summer-solstice
>
> Get your sundial prototypes ready to test, it won't be long before the
> special moment comes!
>
>
> Best,
>
> Jim Tallman
> www.spectrasundial.com
> www.artisanindustrials.com
>
> jtall...@artisanindustrials.com
> 513-253-5497
>
> This message is being sent remotely as I am currently out of the studio.
> Please excuse any further delay in response.
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re:

[Bill Gottesman]

Very nice, Ken.  Graphics seem to be a perfect match and seem very
precise.  Are they vinyl, or paint, or anodizing?

-Bill

2018-05-03 21:37 GMT-04:00 clarkkr--- via sundial :

> Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
> eigentliche Nachricht steht dadurch in einem Anhang.
>
> This message was wrapped to be DMARC compliant. The actual message
> text is therefore in an attachment.
>
> -- Forwarded message --
> From: clar...@aol.com
> To: sundial@uni-koeln.de
> Cc:
> Bcc:
> Date: Thu, 3 May 2018 21:37:55 -0400
> Subject: My new public sundial
> Hi Everyone,
>
>  I designed a new sundial for Rita's in Elizabethtown, PA and I
> installed it this week.
> I used the Shadows program  and CorelDraw. The sundial is on 18" aluminum.
>
> Ken Clark
> Elizabethtown, PA
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: New indoor sundial with lens/mirror

[Bill Gottesman]

Hello Kurt,

Fun video.  I'm sure the construction was harder than it looks.

Why are the indoor hour lines curved?  How is this different from a
gnomonic projection, which has straight hour lines?

-Bill


On Sat, Apr 21, 2018 at 8:33 AM, Kurt Niel  wrote:

> Hi All,
>
> just added two videos about final works:
> 1) about the indoor sundial:
> https://m.youtube.com/watch?v=WzyvEpsEL8A
> 2) about the outdoor sundial:
> https://m.youtube.com/watch?v=mdw9mLih6gE
>
> Kurt
>
> Am 20.04.2018 3:32 Nachm. schrieb "Kurt Niel" :
>
> Hi all,
>
> proudly presenting my latest sundial within a primary school here in Upper
> Austria:
> https://kepleruhr.at/su-vs-wallern and
> https://flic.kr/s/aHsm9EgPtL
> Bending mirror because of the narrow lightwell.
>
> Cheers
> Kurt
> https://kepleruhr.at
>
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: New indoor sundial with lens/mirror

[Bill Gottesman]

Hello Kurt, Congratulations on completing a challenging project.

I would like to ask a few optical questions.
Why did you use a lens at all?  In my experience, a lens differs from an
open aperture in that it distorts the path of the sun.  For example,
straight lines, if they are off-axis, are projected as curves.  Even
on-axis lines become shortened or lengthened non-linearly.  Were you able
to accommodate this into your design?  (I don't know if a prism, as
suggested by Ricahrd Pauli also distort the path of the sun)

A small flat circular mirror, with no lens, is more simple and compact
design, but has its own limitations, too.  Did you rule out this option?

-Bill

On Fri, Apr 20, 2018 at 12:10 PM, R.Pauli  wrote:

> Spectacular!Techno-Modern-Gnomonics.
>
>  Almost a reverse display, instead of shadow, the point of light is the
> display.   Sort of a reflecting gnomon -rather than a shadow.   In my
> translated page it is called a shadow - but should there be a different
> term for a concentrated spot of light?   Maybe a 'negative' display?
>
> For the next version, I would want to see a prism that eould expand and
> colorize the light.  Although I am unaware of the challenges of deploying
> glass optics.
>
> Superb design.   thanks
>
> Richard Pauli
>
>
> On 4/20/2018 6:32 AM, Kurt Niel wrote:
>
> Hi all,
>
> proudly presenting my latest sundial within a primary school here in Upper
> Austria:
> https://kepleruhr.at/su-vs-wallern and
> https://flic.kr/s/aHsm9EgPtL
> Bending mirror because of the narrow lightwell.
>
> Cheers
> Kurt
> https://kepleruhr.at
>
>
>
>
> ---https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Solar math

[Bill Gottesman]

I don't know any software, but my approach would be:

1. Use Altitude and Azimuth and Latitude to calculate Declination
(straightforwad Spherical Trig calculation. If you need formula, it will
take me a moment to come up with it)

2. Calculate dates for the declination (longitude/time zone will matter).
This should not be too hard to look up (or should be findable at link below)

3. Calculate time from declination, location, time zone, daylight saving.
OR create an azimuth/altitude table for a given date at
http://aa.usno.navy.mil/data/docs/topocentric.php .  Be sure to select for
Apparent Topocentic Zenith Distance and Azimuth.  Times are given in UTC.

-Bill

On Thu, Mar 22, 2018 at 10:47 AM, Dan-George Uza 
wrote:

> Dear all, given the azimuth and altitude of a point in the sky, what would
> be the best way of finding the dates and times during which the Sun reaches
> that point? Is there any software for this?
>
> Dan Uza
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: St. Valentin

[Bill Gottesman]

Very helpful, Gian.  I hope to try this sometime.

-Bill

On Wed, Feb 14, 2018 at 2:37 PM, Gian Casalegno <gian.casale...@gmail.com>
wrote:

> This is the list of the s/w programs involved.
>
> - Orologi Solari: gnomonic design of the bifilar sundial.
> The output is a DXF file containing all the elements of the sundial as
> wires (no thickness,  no shadow)
>
> - CAD program: 3D processing of the DXF file
> All the wires are given a phisical thickness i.e. they become 3D objects.
> The wall also becomes a 3D object that can receive the wires shadow.
> The sundial is also correctly oriented according to wall declination and
> inclination.
> The result is saved as a DWG file
>
> - SketchUp: 3D rendering and sun simulation
> The DWG file is imported into SketchUp.
> The 3D model is again worked for cosmetics only.
> The model is geolocalized.
> Sun simulation is then used to create different views of the sundial at
> different dates and times.
>
> Hope this answers your question.
> Do not hesitate to contact me again for any additional detail.
>
> Ciao.
> Gian
>
>
>
>
> <https://www.avast.com/sig-email?utm_medium=email_source=link_campaign=sig-email_content=webmail>
>  Mail
> priva di virus. www.avast.com
> <https://www.avast.com/sig-email?utm_medium=email_source=link_campaign=sig-email_content=webmail>
> <#m_-4867647885745656337_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>
> 2018-02-14 20:23 GMT+01:00 Bill Gottesman <billgottes...@comcast.net>:
>
>> Very topical for today.
>>
>> How are those images generated?  What are the different softwares
>> involved?
>>
>> -Bill
>>
>> On Wed, Feb 14, 2018 at 4:55 AM, Reinhold Kriegler <
>> reinhold.krieg...@gmx.de> wrote:
>>
>>>
>>>
>>> https://www.youtube.com/watch?v=mZBwBqIbwYw
>>>
>>> HAVE A LOOK AND ENJOY!
>>> A most charming idea by Gian Casalegno!
>>>
>>> Reinhold Kriegler
>>>
>>>
>>>
>>> * ** ***  * ** ***
>>>
>>> Reinhold R. Kriegler
>>> Lat. 51,8390 N. Long. 12,25512 E. GMT +1 (DST +2) www.ta-dip.de
>>> <http://www.ta-dip.de/dies-und-das/die-niederpoeringer-radrennbahn.html>
>>>
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>>
>>>
>>>
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: St. Valentin

[Bill Gottesman]

Very topical for today.

How are those images generated?  What are the different softwares involved?

-Bill

On Wed, Feb 14, 2018 at 4:55 AM, Reinhold Kriegler  wrote:

>
>
> https://www.youtube.com/watch?v=mZBwBqIbwYw
>
> HAVE A LOOK AND ENJOY!
> A most charming idea by Gian Casalegno!
>
> Reinhold Kriegler
>
>
>
> * ** ***  * ** ***
>
> Reinhold R. Kriegler
> Lat. 51,8390 N. Long. 12,25512 E. GMT +1 (DST +2) www.ta-dip.de
> 
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Kepler

[Bill Gottesman]

Lord knows how you came up with this.  -Bill

On Fri, Jul 7, 2017 at 5:46 AM, fabio.sav...@nonvedolora.it <
fabio.sav...@nonvedolora.it> wrote:

> Hi, I just finished  a work that has engaged me in the last two weeks.
>
> For those are interested about the Kepler's laws, it
>
> ---
> New Outlook Express and Windows Live Mail replacement - get it here:
> http://www.oeclassic.com/
>
> is an orrery to show the true anomaly starting from the mean anomaly.
>
> The mathematical formula expresses the mean anomaly as a function of the
> eccentric anomaly, function of the true anomaly (the true anomaly is the
> angle of the vector ray that sweeps out equals areas during equal intervals
> of time)
> The problem is that the first formula is not reversible. There are some
> iterative mathematical methods to get the eccentricity anomaly from the
> mean one, with several steps up to the desidered approximation, or it is
> possible the resolution into an infinite series of terms but not a direct
> formula.
>
> Here math limps. But what can not be achieved with a formal language can
> be at hand by changing the language, so suggests Godel.
> So I designed a gear structure to get the mean anomaly from the eccentric
> one, like the formula, ma the movement of the gears, unlike the formula,
> can work contrariwise.
> I attached an image of an orrery, for the moment it is virtual, where
> turning a knob with a costant angular velocity, the mean anomaly, you get
> the movement of a planet on an elliptical orbit, following the Kepler's
> laws.
> The turquoise planet follows the true anomaly and the one outside the
> zodiac follows the mean anomaly.
> This orrery is setted with an eccentricity of 0.7216, far higher than he
> Earth's one (0.0167086), to point out the gear's dinamic and the elliptical
> movement.
> I also upload a video on youtube: https://youtu.be/Y5eSOfd5Imk
>
> This work is the entrance door to calculate the eot with gears instead to
> use the customary cam, this is the target for some future gnomonic projects.
>
> ciao Fabio
>
> Fabio Savian
> fabio.sav...@nonvedolora.it
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: sunflower

[Bill Gottesman]

Another fabulous Fabio sundial!  Clever and fun. -Bill

On Mon, Jun 5, 2017 at 5:03 AM, fabio.sav...@nonvedolora.it <
fabio.sav...@nonvedolora.it> wrote:

> Hi all
>
> I just finished to design an horizontal sundial adjustable for a range of
> latitude, in this case from 30° N to 50° N, I also built it with laser cut
> plywood.
> Revolving the sunflower changes the angle of the polar style, the latitude
> is engraved (always by laser) at the base of the sunflower, a green arrow
> on the horizontal dial point out to it.
>
> ciao Fabio
>
>
> ---
> New Outlook Express and Windows Live Mail replacement - get it here:
> http://www.oeclassic.com/
>
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Brass or Bronze for Sundials.

[Bill Gottesman]

Not all brass/bronze is the same.  I prefer silicon bronze.  It is typical
for large outdoor sculptures, and also marine hardware and propellers.  It
turns dark, not green, and is very durable.  -Bill

On Sun, Jun 4, 2017 at 9:58 PM, rodwall1...@gmail.com  wrote:

> Hi all,
>
> For a sundial that will be out in the weather. What is the
> advantage/disadvantage of using brass or bronze?
>
> Regards,
>
> Roderick Wall.
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Mounting Sundials...securely

[Bill Gottesman]

Tony Moss described a secure and permanent mounting method using bolts
permanently fixed to the underside of the dial.  The dial is then set in
mortar atop the pedestal, and the bolts become permanently fixed in the
mortar.  Lord knows how this could be removed later.

Another method involved using a silicone adhesive to fix the dial to the
pedestal (no bolts).  Use cardboard spacers to ensure an 1/8" gap from the
pedestal surface.  If it ever needed to be removed, it cold be separated
from the pedestal by cutting under the dial with a flexible hacksaw blade.

-Bill

On Tue, May 16, 2017 at 5:19 PM, rodwall1...@gmail.com <
rodwall1...@gmail.com> wrote:

> Hi all,
>
> In the Ranelagh Estate at Mount Eliza Victoria 3930 Australia. There is a
> memorial to John Thomas Smith in Ranelagh drive. The memorial was
> surmounted by a sundial. It was there as late as 2004. It was removed by
> unknown people several times and was replaced by the shire. But the shire
> eventually gave up as the sundial could not be adequately secured.
>
> Question, does anyone know of a way to adequately secure a sundial on the
> following memorial?
>
> http://monumentaustralia.org.au/themes/people/settlement/
> display/32753-john-thomas-smith
>
> It is such a shame that we all can't enjoy a sundial. Without someone
> thinking that they should have it for themselves only.
>
> Thanks,
>
> Roderick Wall.
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

S-Town, John B McLemore

[Bill Gottesman]

Hello Sundial Listers,

I was wondering if anyone of us knew John B Mclemore, the Horologist
protagonist of the This American Life radio show S-Town.  The story
includes his fascination with sundials and astrolabes.  Was he known to any
of us?

-Bill
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Astronomy Day and Sundials

[Bill Gottesman]

Hello Ken,

Fantastic display.  I hope you had fun and a lot of interested visitors.
 -Bill

On Sat, May 6, 2017 at 8:15 AM, Kenneth R clark 
wrote:

> I am not sure my post went through. Trying again.
>
> Hi everyone,
>
>
>  I was invited back to the North Museum in Lancaster PA to do another
> educational sundial display for Astronomy Day last week.  I made a 36 inch
> x 16 inch polar dial on paper promoting the event using the Shadows program
> and CorelDraw program.
>
>
>  I always like promoting sundials and NASS and you can see some
> pictures from my FACEBOOK link:
>
>
> https://www.facebook.com/media/set/?set=a.10209478625058579.1073741834.
> 1114522471=1=e52ad96065
>
>
> Thanks,
>
> Ken Clark
>
>
>
>  Elizabethtown, PA
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Astronomy Picture of the Day (Again)

[Bill Gottesman]

That was awesome, Bob.
-Bill

On Wed, Dec 21, 2016 at 8:43 AM, Robert Terwilliger 
wrote:

> This is a good one!
>
>
>
> Traces of the Sun
>
> http://apod.nasa.gov/apod/ap161221.html
>
>
>
> Bob
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Enquiry relating to the wide polar gnomon and its midnight overlap in polar area

[Bill Gottesman]

Why is the Longyearbyen sundial irrelevant to your project?
- Bill

On Friday, July 22, 2016, Helmut Haase  wrote:

> Hi all,
> When studying the wide polar gnomon one inevitably encounters edge changes
> to be respected. My special focus is on a horizontal dial for a location
> with midnight sun. Around midnight the scale needs two overlapping
> sections. I have designed a solution based on a uniformly convoluted spider
> scale (see attached jpg (203 kB)).
>
> My question: *Is a comparable dial existing anywhere?* My web research
> produced only nil returns. The closest but not relevant hit is the 
> Longyearbyen
> sun dial .
>
> Kind regards
> Helmut Haase
>
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: A Happy Leap Year Day to everyone

[Bill Gottesman]

Thank you Frank!  What a fun thing to know!  -Bill

On Wed, Feb 24, 2016 at 3:11 AM, Frank King  wrote:

> Dear All,
>
> As is my four-yearly custom, I wish readers of
> this list a Happy Leap Year Day.
>
> I was delighted, in 2012, when I sent out a
> similar greeting, that not a single reader
> queried why I had sent out the message on
> 24 February.
>
> I will add my four-yearly lament that the
> perfectly good English term "bissextile year"
> seems to be almost obsolete.  Around 100 years
> ago it was in fairly common use.
>
> I continue to applaud the French, the Italians
> and the Portuguese (just to give three examples)
> who still use année bissextile, anno bisestile
> and ano bissexto.
>
> Let us hope that they do not indulge in the
> dumbing-down from which we in the U.K. seem
> to suffer.
>
> Frank King
> Cambridge, U.K.
>
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: 3D digital sundial

[Bill Gottesman]

Very cool.  Has anyone had a chance to try the free 3D software OpenScad?
By the way, I am skeptical that the sundial can handle declinations near
the solstices.
-Bill

On Fri, Nov 6, 2015 at 7:39 AM, Darek Oczki  wrote:

> Hello everyone
>
> Have you seen this 3D digital sundial?
> http://3dprint.com/103289/open-source-3d-print-sundial/
>
> --
> Best regards
> Darek Oczki
> 52N 21E
> Warsaw, Poland
> GNOMONIKA.pl
> Sundials in Poland
> http://gnomonika.pl
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: NASS site down?

[Bill Gottesman]

Yay!

On Sun, Nov 1, 2015 at 9:53 PM, Jack Aubert <j...@chezaubert.net> wrote:

> Yes, the server died, but has been resurrected with some replacement
> hardware.  It is back up and running now.
>
>
>
> Jack Aubert
>
>
>
> *From:* sundial [mailto:sundial-boun...@uni-koeln.de] *On Behalf Of *Bill
> Gottesman
> *Sent:* Saturday, October 31, 2015 8:07 PM
> *To:* Sundials List <sundial@uni-koeln.de>
> *Subject:* NASS site down?
>
>
>
> Sundials.org is unavailable tonight.  Anyone aware of a problem?
>
>
>
> -Bill Gottesman
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

NASS site down?

[Bill Gottesman]

Sundials.org is unavailable tonight.  Anyone aware of a problem?

-Bill Gottesman
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: due east photos

[Bill Gottesman]

Well, if you are going to allow compass directions, then that opens the
door to all loxodromes.  There are an infnite number of loxodromes that
connect two points on a sphere, if you allow loxodrome paths that travel
more than once around the globe!  This gives an infinite number of compass
directions to Mecca.

-Bill

On Thu, Sep 24, 2015 at 4:11 PM, Brent  wrote:

> I think you can face Mecca from 4 directions:
>
> 1. along great circle shortest direction
> 2. along great circle longest direction
> 3. along constant compass method shortest direction
> 4. along constant compass method longest direction
>
> I wonder if it says in Koran to face Mecca in shortest direction?
>
> brent
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: A Digital Sundial on Instructables

[Bill Gottesman]

Brilliant.  First dial I've seen like that. Thanks for sharing
-Bill

On Thu, Apr 23, 2015 at 8:24 AM, Richard B. Langley l...@unb.ca wrote:

 Came across this, this morning:
 http://www.instructables.com/id/Time-oclock-shadow/
 --Richard Langley


 -
 | Richard B. LangleyE-mail: l...@unb.ca
|
 | Geodetic Research Laboratory  Web: http://gge.unb.ca/
|
 | Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
  |
 | University of New Brunswick   Fax:  +1 506 453-4943
  |
 | Fredericton, N.B., Canada  E3B 5A3
   |
 |Fredericton?  Where's that?  See: http://www.fredericton.ca/
|

 -

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Die Grieskirchner Kepleruhr

[Bill Gottesman]

Awesome dial.  I have never seen a gapped nodus like that before, not have
I seen the use of mirrors to project an image for when the sun is behind
the wall.  Please tell us who designed this dial, and how it was
commissioned?  I could not find that information in the article.  I work
with mirror gnomons, and am interested in how the installers fine-tuned the
mirror alignment.  Did the mirrors have an adjusting mechanism, and did the
designer have a plan for alignment post-installation?
-Bill

2015-04-13 8:47 GMT-04:00 Josef Pastor j.pas...@gmx.de:

  Liebe Sonnenuhrenfreunde,



 die neue „Sterne und Weltraum“ Heft 5-2015, die ab morgen im gut
 sortierten Zeitschriftenhandel erhältlich sein wird, berichtet auf den
 Seiten 66-72 ausführlich über die „Grieskirchner Kepleruhr“, einer
 vertikalen, ebenen Sonnenuhr.





 Dear Sundialists,



 the German speaking Astromagazine „Sterne und Weltraum“ Vol. 5-2015
 provides an report on the „Grieskirchner Kepleruhr“, which is an vertical,
 plane sundial.





 http://www.spektrum.de/inhaltsverzeichnis/mai-2015/1313010



 Viele Grüße

 Best regards

 Josef Pastor



 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Clouding the issue

[Bill Gottesman]

That is an excellent question!  I have seen this photo before, and never
noticed the numbers running twice in a semicircle.  I, too, am perplexed.
I read about this dial in Hester Higton's book Sundials at Greenwich.
 The dial operates on two successive polarizations of light - the first
being when light passes through the selenite strips on the glass, and the
second when light reflects at the the polarizing angle (Brewster's
angle?) off of the inclined dark glass plate behind the front glass.  At
all times of the day the radii will appear of various shades of two
complementary colours.  This is different than how a single piece of
polarized film would be used today.

Does this help anyone figure this out?
-Bill

On Mon, Mar 30, 2015 at 3:48 PM, Maes, F.W. f.w.m...@rug.nl wrote:

 Hi all,

 Wheatstone designed still another type of polarization dial than the one
 described by Jim Mahaffey. A specimen is in the collection of the British
 National Maritime Museum in Greenwich, see
 http://collections.rmg.co.uk/collections/objects/265579.html.
 When viewing the celestial pole, the polarization pattern of the sky is
 visible, consisting of two light and two dark regions, which rotate around
 the pole together with the sun.
 What I don't understand from the NMM dial: why does it have twice the hour
 numbers from 1-12 in a semicircle, while the sun rotates through 24 hours
 in a full circle?
 Allan Mills made a modern version, using sellotape instead of selenite;
 see BSS Bulletin 1998 nr. 1. It has one set of 1-12 hour numbers in a
 semicircle, as one would expect.

 Best regards,
 Frans Maes

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: A question for the mathematically inclined

[Bill Gottesman]

You can download a free excel spreadsheet, sunpositioncalculator at
http://precisionsundials.com/sunpositioncalculator.xls.  The Azimuth page
allows you to input date, latitude, longitude, and azimuth, and it gives
you the civil time, eot, declination, and altitude.  When opening, you must
allow macros to run if the computer asks.

-Bill

On Sat, Jan 31, 2015 at 10:49 AM, Richard B. Langley l...@unb.ca wrote:

 If you know the zenith distance, z, of the sun (90° - elevation angle) as
 well as the azimuth (A) then you could use:

 sin(h) = -sin(z)*sin(A)/cos(delta)

 where delta is the sun's declination. The latitude of the site, phi, is
 not needed.

 Computing the hour angle when the zenith distance is not known is a little
 trickier. In principle, this equation could be used:

 sin(h) = tan(A)*(sin(phi)*cos(h) - cos(phi)*tan(delta))

 but you'll notice that h appears on both sides of the equation. Possibly
 this can be solved in an iterative fashion by selecting an approximate
 trial value for h and using it on the r.h.s. to compute a new value of h.
 You would then use this new value on the r.h.s. and continue the iterative
 procedure until the new value does not change significantly from the
 previous value. I've not actually tried this myself so proceed with caution.

 -- Richard Langley

 On Saturday, January 31, 2015, 31, at 11:05 AM, John Goodman wrote:

  Dear dialists,
 
  Does anyone know a formula for calculating the hour angle given the
 azimuth, declination, and latitude?
 
  I’d like to know the time of day, throughout the year, when the sun will
 be positioned at a particular angle. This will allow me to determine when
 sunshine will stream squarely through a window on any (sunny) day.
 
  I’ve seen several formulae for calculating azimuth. I suspect that one
 of them could be rewritten to solve for the hour angle given the azimuth
 instead of the finding the azimuth using the hour angle (plus the
 declination and latitude). Unfortunately, I don’t have the math skills for
 this conversion.
 
  Thanks for any suggestions.
  ---
  https://lists.uni-koeln.de/mailman/listinfo/sundial
 


 -
 | Richard B. LangleyE-mail: l...@unb.ca
|
 | Geodetic Research Laboratory  Web: http://gge.unb.ca/
|
 | Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
  |
 | University of New Brunswick   Fax:  +1 506 453-4943
  |
 | Fredericton, N.B., Canada  E3B 5A3
   |
 |Fredericton?  Where's that?  See: http://www.fredericton.ca/
|

 -

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: summer house / sundial

[Bill Gottesman]

Very cute!.  If the room rotated to follow the sun's azimuth daily, the
heart would be present much of the day, and would lengthen towards mid-day.
 -Bill

On Thu, Jan 1, 2015 at 2:00 PM, Willy Leenders willy.leend...@telenet.be
wrote:

 I designed a romantic summer house / sundial and I like to hear your
 comments.

 See:
 http://www.wijzerweb.be/zeshoekprieeltje%28eng%29001A.html


 Willy Leenders
 Hasselt in Flanders (Belgium)

 Visit my website about the sundials in the province of Limburg (Flanders)
 with a section 'worth knowing about sundials' (mostly in Dutch):
 http://www.wijzerweb.be








 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: CORRECTIONS Extensions to A few new Tables for the Gnomonist...

[Bill Gottesman]

Well, you could include both ways.  This is a really nice resource you have
provided.  Did you already say the reference for your high precision
calculations?  -Bill


On Thu, Jun 12, 2014 at 1:12 PM, Kevin Karney kar...@me.com wrote:

 Dear Friends

 Thanks for the positive comments!
 And thanks to Gianni Ferrari, Patrick Powers, Edward French and Jack
 Aubert for pointing out the MAJOR error in the Annual Equation of Time
 Table.
 It was giving EoT values *across* the table instead of *down*, which is
 an error I had corrected before - but had crept back in!
 That has been corrected Many apologies

 Also, by popular request,  I have changed the sign of EoT from the strict
 astronomical convention to the more usual gnomonical convention (the
 correction to get from sundial to local mean time).

 Gianni also wants Azimuth measured from the South... I am a 0 deg at North
 person. Any thoughts ? I will probably change things to give a radio
 button, so you can choose.

 I have had requests for a solar noon table and solar east/west table and a
 half-minute Victorian table - which I shall implement in due course

 Best wishes
 Kevin

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: paperhenge

[Bill Gottesman]

Paper henge is totally awesome.  -Bill


On Wed, Jun 4, 2014 at 7:08 AM, Fabio nonvedolora 
fabio.sav...@nonvedolora.it wrote:

   Hi all

 on sunday there was the ‘Festa delle Meridiane’ (sundial feast) in Aiello,
 a village in the NorthEast of Italy where there are 104 sundials and 2252
 inhabitants.
 There also was a contest to vote for the new 4 sundials (the winner is
 IT11058, Sundial Atlas) and a stand of Orologi Solari (
 www.orologisolari.eu), the italian magazine about gnomonics.

 I prepared for them a paper display that I called paperhenge: it is an A1
 paper sheet (594 x 841 mm or 25.5 x 36.1 in) with a solar compass in the
 middle, outlined for Aiello, and a layout to place 9 paper sundials, on a
 circle, from 120 E to 120 W, every 30°.
 The paper models are the n. 3 of Gnomolab -Sundial Atlas, working with a
 pinhole, printed with different background images, line colours, ecc.
 I draw the layout with Indesign and I got the executive pdf (6.3 MB) for
 digital print. I can easily adapt the layout for other place and event, if
 anyone is interested to paperhenge I’ll be glad to custom it.
 I attach an image, other photos are on Sundial Atlas to describe the
 event.

 The event is in menu ‘gnomonics’  ‘happenings’  choose in the right
 column ‘shows the events of the past’  choose ‘14a Festa delle Meridiane’
 or click here: www.sundialatlas.eu/atlas.php?show=85
 The ‘path’ with all the sundials is ‘le meridiane di Aiello’

 ciao Fabio

 [image: DSCN5931c]

 Fabio Savian
 fabio.sav...@nonvedolora.it
 www.nonvedolora.eu
 Paderno Dugnano, Milano, Italy
 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2)

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Using the moon to find south [SEC=UNOFFICIAL]

[Bill Gottesman]

Thanks, Hank.  Very helpful observations.  The ecliptic north pole lies in
the curve of Draco's (The Serpent) neck.  From your explanation, it seems
that the line connecting the crescents of the moon should always point
approximately to that location, and this should be something easy to test
in the night sky.  Is there a way to use this information (perhaps the time
of year) to help refine finding south by the moon's crescent?  -Bill


On Mon, May 12, 2014 at 3:07 AM, Hank de Wit h.de...@bom.gov.au wrote:

 HI Steve,

 I think I can answer this one approximately. The maths is also beyond me,
 but we can get an intuitive answer without causing too much brain strain.

 The first point to remember is that both the Sun and the Moon travel on
 paths nearly along the Ecliptic. The Sun sits exactly on the Ecliptic, and
 the Moon, deviates plus or minus 5 degrees, because it's orbit is inclined
 by 5 degrees to the Ecliptic. This means that that shadow of the terminator
 between light and dark on the moon must be aligned nearly perpendicular to
 the path of the Ecliptic in the sky - they are in the same plane. So the
 problem reduces to the angle that the path of the Ecliptic makes in the sky.

 To reduce variables even more, let's just think about the Moon when it is
 highest in the sky, along the meridian through South (North in the SH).

 We need a planisphere to visualise, and I found a nice online one here:
 http://drifted.in/planisphere-app/app/index.xhtml

 This planisphere has the Ecliptic marked as a blue line in the sky. If you
 rotate the outer disk to move through the months, and imagine the Moon
 along the Ecliptic and sitting on the north-south meridian you can clearly
 see the tilt of the Ecliptic line, and therefore the line through the horns
 of the Moon if it were located at that point. You can see that this line is
 not directly through north for most of the year, and can be either side.
 The biggest deviations are at the two equinoxes. It is pointing south
 (north) at the solstices. I wonder if the amount of maximum deviation from
 due south (north) is plus and minus 23.5 degrees.

 Many regards
 Hank

 -Original Message-
 From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Steve
 Lelievre
 Sent: Sunday, 11 May 2014 12:22 AM
 To: sundial@uni-koeln.de
 Subject: Using the moon to find south

 Hi folks,

 Only loosely related to my question just posted, I'm interested to know
 more about a primative navigation method I've read of. The idea is that if
 one projects an imaginary line through the cusps of a crescent moon down to
 the horizon, that gives the approximate position of South (or perhaps North
 depending on your hemisphere).

 How accurate is this position compared to true south? I'm guessing it
 depends on the time of year, phase of moon and latitude - can any one
 supply formulae? Working it out from first principles is beyond my math
 ability.

 I'm thinking that if I can use the moon to find south, I can then measure
 the azimuth of the sun and use that to get time of day...

 Thanks,
 Steve





 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: The Bill Gottesman stance

[Bill Gottesman]

I say we tack on as many names as possible.  Roger Bailey told me a few
years ago he reported on this stance independently.  -Bill


On Sat, May 10, 2014 at 3:40 PM, Robert Terwilliger b...@twigsdigs.comwrote:

  I have always been of the opinion that the optimal stance to assume as
 the gnomon of an analamatic sundial is to stand with one’s back to the sun
 with arms raised and palms together thus forming an arrow. What has been
 referred to as “The Gottesman Stance” would certainly be  a significant
 improvement.



 I’m sure my friend Bill will agree with me that hereinafter in the
 literature the combination should be referred to as “The
 Terwilliger/Gottesman Stance”.



 What say you?



 ò¿ó¬

  ~

 Bob











 The Gottesman stance

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Sun tracks

[Bill Gottesman]

Here is what I think:
The can is laying on its side with its axis oriented north-south.  A
pinhole is made on the west side of the can (assuming this location is in
the northern hemisphere, and that the zenith of the sun is toward the
south), pointing upward at about 45 degrees.  It captures the sun before it
has reached solar noon, then tracks it all the way to sunset in the west.
 The tracks of the morning sun at the top of the picture appear to
converge; this effect comes from that edge of the film being so close to
can's the pin-hole, where all light rays converge at their origin.  (The
film is wrapped around the inside of the can)

-Bill


On Mon, May 5, 2014 at 8:43 AM, John Foad john.f...@keme.co.uk wrote:

 So . . . what is the explanation?  From the angle of the tracks it looks
 quite far north (or south).  Can the curvature of the soup can do it?  I
 can't see how, whether it was vertical or horizontal.

 John

 -Original Message- From: Thibaud Taudin Chabot
 Sent: Monday, May 05, 2014 10:11 AM
 To: Sundial list
 Subject: Re: Sun tracks


 Do I see a retrograde? (Same azimut, different moments). Where is
 this picture made?
 Thibaud

 At 21:33 4-5-2014, Barry Wainwright wrote:

 The BBC has a series of pictures taken by pinhole camera at
 http://www.bbc.co.uk/news/in-pictures-27221895

 Image 7 is described thus:
 John Rigg: This is a six-month exposure using a pinhole camera made from
 an empty soup tin and photographic paper, not film. The resulting image is
 then scanned and reversed. The trails mark the path of the sun across the
 sky as the seasons change. Days with broken cloud show as a dotted line.

 --
 Barry

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial


 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Most accurate Sundial in the World

[Bill Gottesman]

That is pretty bold claim, one which I do not make with my own dials.  This
dial is designed to be readable to 5 seconds, but accuracy could be another
matter.  There are so many variables that affect accuracy, and some are
easily overlooked.  Specifically, critical alignment with the north
celestial pole is extremely hard to achieve.  A magnificently designed dial
can perform only as well as its installation will allow.  Accuracy related
to alignment varies with time of day and the sun's declination;  I have not
done the math for a while, but I think even a misalignment by 1/10th of a
degree an any direction will preclude accuracy of say, 15 seconds for a
least part of the day, during some part of the year.  Year-on-year
variation in the EoT is another matter, but could be properly compensated
if accounted for.

Claims of accuracy (for civil time) can be evaluated only by simultaneous
measurements of dial and clock at different times of day, and different
times of the year.  Even a broken watch is accurate twice a day.

-Bill



On Sun, Apr 13, 2014 at 9:54 AM, cerculdestele . cerculdest...@gmail.comwrote:

 Does anyone know if this record has been broken?


 http://www.engadin.stmoritz.ch/sommer/en/activities/mountain-adventure/mountains/muottas-muragl-mountain-adventures/sundial-muottas-muragl/

 Dan Uza
 Romania

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Calculating the Equation of Time and other Solar Parameters

[Bill Gottesman]

Kevin,

I am excited about your article Basic Astronomy for the Gnomonist.  It
will take some time to digest, but it seems to have a very nice graphic
analysis for the many formulas and solar positioning we deal with.  I
appreciate you making this reference available.

I think what you call a Hectoromos dial is what I have heard described as a
Singleton dial.  Here is a link to a similar (vertical) dial at the
University of Vermont.  Fred Sawyer wrote about the Hectoromos dial in an
early NASS compendium.  I think Plato might have had something to do with
it.

-Bill


On Sun, Feb 23, 2014 at 2:32 PM, Kevin Karney kar...@me.com wrote:

 Dear Friends

 I have spend many happy hours during this wet, wet winter investigating
 and learning how to calculate all the solar parameters that a
 gnomonist might possibly need  - Equation of Time, Declination, RA,
 Altitude, Azimuth, Time of Sunset/Rise, etc, etc.

 I have been surprised to find that - with traditional calculation methods
 and an absolute minimum of astronomical information -  it is possible to
 calculate everything from first principles to a surprising degree of
 accuracy.

 Other than location and local time, only six pieces of astronomical
 information are required - obliquity, eccentricity, Sun's GHA at 1/1/2000,
 longitude of perihelion, a single precessional constant and the length of
 the tropical year. Accuracies for the EOT are +/- 2 seconds of time For
 altitudes/azimuths, less than 1 minute of arc - much better than needed by
 most gnomonic problems.

 If any of you are interested in such calculations, I have loaded a
 document with all the astronomical theory and background plus the code onto
 my website
 *www.precisedirections.co.uk/sundials
 http://www.precisedirections.co.uk/sundials*
 The code is written in Python, a language available on every type of
 computer, which is very easily understood, quite easily learnt and very
 easily translated into any other coding language you might like.

 If you own an iPad or iPhone, and are prepared to buy a cheap little app
 called Pythonista, the code will extract locational  time information from
 your phone - so you do not even have to input this to get your calculations
 done

 You might also like to see a graphic of a civil mean time horizontal dial,
 which *I think* is called a hectomoros dial,  that is destined for my
 garden. This is also on the website.

 Enjoy
 Kevin

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Aussie hours til sunset dial

[Bill Gottesman]

Great Story, Jim.  Mac Oglesby has been a strong proponent of Hours to
Sunset dials for years.  This one is magnificent, thanks for sharing it.
 -Bill


On Tue, Nov 19, 2013 at 4:17 PM, J. Tallman jtall...@artisanindustrials.com
 wrote:

 Hello All,



 I got a link today from a Spectra owner about a really big sundial project
 near him, and I thought some of you might be interested:



 http://hourstosunset.com/



 Here is a pic that shows the aperture nodus:




 http://www.news.uwa.edu.au/201302055408/arts-and-culture/new-shaun-tan-sundial-marks-100-years-uwa



 They have a video available at the first site showing the scale of the
 thing and how the mosaic was installed, in numbered sections. Interesting!





 Best,



 Jim Tallman

 www.spectrasundial.com

 www.artisanindustrials.com

 jtall...@artisanindustrials.com

 513-253-5497



 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

08:09:10 11/12/13

[Bill Gottesman]

Did anyone catch this auspicious moment, 08:09:10 11/12/13?  I missed it,
but will go for another try this PM.

-Bill
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Ragtime/Jazz sundial lyric

[Bill Gottesman]

Hello Sundial-Listers,

By happenstance I found a piano roll video performance of Lu-Lu-Lou
(1920's?).  One of the verses ends with:

Lu Lu she's so dumb she'll soon be in the booby hatch
I saw her telling time last night on a sundial with a match.

I don't really recommend the performance, but it is here:
http://youtu.be/o2gscYRU2U4 .  Verse starts at 1:52.

-Bill
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Advice please: Good outdoor surface for painting an analemmatic dial

[Bill Gottesman]

I used a paint for concrete on asphalt for an analemmatic about 13 years
ago.  It held up for a few years at least, but then the school repaved the
area.  -Bill G.


On Thu, May 2, 2013 at 3:37 PM, Tom Kreyche tkrey...@well.com wrote:

 Search on Tennis Court Paint and you will get all kinds of interesting
 info...some advertise minimal surface prep and they are non-skid. Most
 appear to be acrylic. I haven't used any but am considering for a
 schoolyard project as wellTom

 --
 *From: *rPauli rpa...@speakeasy.org
 *To: *sundial@uni-koeln.de
 *Sent: *Thursday, May 2, 2013 12:25:24 PM
 *Subject: *Re: Advice please: Good outdoor surface for painting an
 analemmaticdial


 Acrylic concrete adheres nicely, takes coloring well.  But it is toxic as
 it is applied, then dries hard, safe and durable.   Any concrete/plaster
 provider should have good advice about products that adhere to asphalt.  My
 local one is  http://www.sbsg.com/concrete/overview/

 On 5/2/2013 11:55 AM, gerard sheldon wrote:

  re:  Good outdoor surface for painting an analemmatic dial

 I am helping a local school make a human sundial, i.e. an analemmatic
 one, and the school is enthusiastic about the idea.  (My daughter is a
 pupil at that school.)  I have been liaising with the art teacher, and
 the suggestion is that one or more students studying art would mark out
 the layout of the dial on the tarmac/asphalt ground, and then paint on it.
So both a scientific and artistic project.

 The difficulty we face is that the tarmac/asphalt surface is quite grainy
 and not good to paint on.  Do you have any advice on how to get a good
 smooth outdoor surface to paint on (and we want the surface to retain the
 paint) ?

 Any advice would be appreciated.

 Thanks

 Gerard




 ---https://lists.uni-koeln.de/mailman/listinfo/sundial



 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Alt Augsburg revisited

[Bill Gottesman]

I will start a guess.  I think the Hour hand below the gnomon was to be set
manually by the user to align with the shadow line from the gnomon.  This
hand was mechanically linked to the central clock dial minute hand, to show
minutes past the hour.  In this manner, a user would use the sundial to get
a close estimate of the exact time, told by an hour hand and a minute hand.
 There exist other less complicated examples of German dials using a minute
hand mechanically linked to some kind of moveable shadow indicator.

The other clock dials seem to show day-of-week and day of month, and maybe
a lunar calendar as well.  Maybe there is an equation of time mechanism as
part of the calendar, but I can not tell.  How these would function, I have
no idea, but I can't imagine that they were mechanically linked to the
sundial.

-Bill


On Fri, Apr 26, 2013 at 8:37 AM, Robert Terwilliger b...@twigsdigs.comwrote:

  I find it curious that nobody chose to respond to, or comment on, the
 instruments illustrated in the book *Kunstuhrmacher in Alt Augsburg* 

 ** **

 I put images online at:

 ** **

 http://www.twigsdigs.com/sundials/kunstuhrmacher/kunstuhrmacher.htm

 ** **

 These instruments had to be expensive, and since there seem to be a few
 surviving, somebody must have purchased and used them.

 ** **

 I have a l lot of questions.

 ** **

  How were these instruments used?

  Were they to be used in sunlight?  If not, what was the gnomon for?

  How and why did the single hand indicate the hours from VI to VI?

   What happened at night?

 Two of them have the sundial-style line and curves to indicate
 declination/astrological sign.

   How did this work?

 ** **

 Is it possible that these instruments were so early that the makers gave
 them the appearance of sundials to give the impression of accuracy to users
 who previously knew only sundials as time keepers?  

 ** **

 The first instrument illustrated is the only horizontal one and it appears
 to have been photographed from the north. It also has a dial (the left one)
 divided into eight segments with engraved illustrations and Latin text I
 wonder what that’s about

  

 Until seeing these photographs I didn’t know such things existed.

 ** **

 Bob

 ** **

 ** **

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: person's height sundial

[Bill Gottesman]

Very nice dial.  For it to be a person's height dial, don't you need to
show where people of different heights must stand?  These heights are
marked on the Argyle Square dial in Australia (at least, I think they are).
You have some nice photos on your web site of dials I have never seen
before.

-Bill


On Sun, Apr 7, 2013 at 12:37 PM, Chiu 邱,Chi lian clc...@mx.nthu.edu.twwrote:

 Dear All:

 I'd like to report a person's height sundial in PuLi (埔里), NanTou (南投),
 Taiwan, Rep. of China.
 It's located right at the main entrance of PuTai Senior High School
 (普台高中), N23.9946, E120.9367 and is accomplished in the Spring of 2010 by
 a young lady, Miss Chin-Li Lin (林秦立)，a landscape architect in Taiwan.

 As you see from the attached Google Earth picture, the C shaped broken
 circle has a diameter of about 25 m. The white radiating lines within the
 circle are hour lines made of granite.
 For larger pictures of the sundial please go to
 http://photo.xuite.net/nycl.chiu/1864525/75.jpg first.
 There shows the first picture of a set of eight. Then type c to go to
 the next and x to go backward.

 When one looks at this kind of dial for time, he'd be facing his shadow.
 But the ladies in the last two pictures turned down this idea for then
 their faces would be in shadow. They said: Looking for time in that way,
 being taken pictures in this way.  Ha ha.

 Best,

  ChiLian Chiu
  N25, E121


 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Art in dialling

[Bill Gottesman]

Hello Fabio,

Marvelous public sundial!  How did you construct the concrete bowl, and
mark the lines so straight?  I imagine it has a drain for water.

-Bill


On Sun, Apr 7, 2013 at 12:14 PM, f...@solariameridiane.it 
f...@solariameridiane.it wrote:

 Hi all
 this is my work in 2006, created for the city of Borgo San Dalmazzo (CN)
 Italy. The development of the project saw the collaboration of Fabio
 Savian.
 I do not know if it falls between the sundials you are looking for.
 www.sundialatlas.eu/atlas.php?so=IT8328

 Fabio Garnero

 Il giorno 06/apr/13, alle ore 21:12, Mario Arnaldi ha scritto:

 Hi all,

 I am working to an article about the Art in dialling and I would like to
 collect high resolution images of sundial made by artists or also artistic
 sundials. I know that not only Italy is the land of art so I would ask if
 there are some dial made by an artist ouside the Alps, or some artistic
 sundial to include as picture in my article. For example I know the famous
 Dalì sundial, the sundials made by Henry Moore, the dial made by Cocteau.
 There is some other dial of that kind?

 Mario Arnaldi



 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: A prize for the worst dial of the year?

[Bill Gottesman]

OK, that one is a contender.  -Bill


On Fri, Apr 5, 2013 at 1:21 PM, brianalbinson brianalbin...@shaw.ca wrote:

  Bob

 Try this one.  Solid bronze from the local hardware store.

 Brian

 On 4/4/2013 5:33 PM, Robert Terwilliger wrote:

  Here’s one 

 ** **

 In my neighborhoodhttp://www.twigsdigs.com/sundials/mayfair/mayfair.html
 

 ** **

 ** **

 Bob

 ** **

 ** **

 ** **

 ** **

 ** **

 ** **

 ** **


 ---https://lists.uni-koeln.de/mailman/listinfo/sundial



 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Sundials of castel parks

[Bill Gottesman]

There is a magnificent public sundial in Australia, seen as a spiral town
square on Google Earth at lat -37.802467, longitude 144.965927 degrees.  It
is flat to the ground, but unlike an analemmatic, it uses the person's
height to tell time, and looks more like a traditional horizontal layout.
 See another photo at http://www.flickr.com/photos/leprecon/97106416/

-Bill


On Tue, Apr 2, 2013 at 2:26 PM, Isabella McFedries 
isabella.mcfedr...@gmail.com wrote:

 In message 
 caf10bvvcvya+c5e5wm82f2fern6n_jogqohagvd6bwdesx0...@mail.gmail.com
   Marton Géza idomes...@mcse.hu wrote:

  Dear All!
 
  I received an invitation to hold a lecture and show sundials of castle
  parks and parks on the world. I ask for your help in this regard where to
  find materials or list about these.
  Regards
 
  Géza Marton
  idomes...@mcse.hu



 There must be hundreds of available pictures, showing sundials used in
 park situations round the world - but in my opinion, the only practical
 ones are Analemmatics (being both 'interactive' and theft-proof).

 However, I am not sure if there are very many of these located at any
 'castles', who usually only have horizontal and wall-mounted versions,
 with maybe an occasional 'armillary sphere' or 'multi-faceted' dial.


 If you think that they might make an interesting addition to your talk,
 I have attached two small photographs - the originals are larger, and
 were taken from the main 'Human Sundial' website at  www.sunclocks.com


 One is a typical park (USA), the other is at a 'castle' (UK) - and I
 hope they will get through the file-size restriction for this List.

 I just wish that Analemmatic sundials were better known - but (if you
 want) there are more pictures of 'park' locations, on that website.

 Sincerely,

 Isabella McFedries.


 --


 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: equation of time sundial

[Bill Gottesman]

Hello All,
I think Mike nailed it, as to what Ken is asking.  I know of no sundial,
other than Mike's here, that directly measures the Eot, rather than somehow
incorporate the EoT calculated elsewhere.  I did not think this was
possible until I saw Mike's solution just now, because a sundial has no way
of measuring Mean Solar Time without a previously calculated EoT chart.  In
Tom Hank's movie Cast Away, he records an analemma on a cave wall, but this
is movie fiction.  His watch was broken and he had no way to measure mean
time, only local solar time.
-Bill

On Sun, Feb 3, 2013 at 5:51 PM, jmikes...@ntlworld.com wrote:

   Ken,

 I think I made a device some time ago to do what you want .

 A cylinder was tilted to the appropriate latitude angle and direction.
 There was a small hole on one side of the cylinder which gave a projected
 a spot of light from the sun on the inner opposite surface where there was
 a graph which showed:
 left to right – the equation of time
 up and down – the sun’s declination.

 The cylinder was driven round using a 24 hour clock motor, so the spot of
 light remained apparently stationary except for changes in the EoT and
 sun’s declination that were read directly from the graph.

 Sadly, I don’t think I have it any more.

 Mike Shaw
 53º 22' North 03º 02' West
 www.wiz.to/sundials


 No virus found in this message.
 Checked by AVG - www.avg.com
 Version: 2013.0.2897 / Virus Database: 2639/6076 - Release Date: 02/02/13

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: NASS Conference

[Bill Gottesman]

Yay!.  -Bill

On Wed, Jan 23, 2013 at 2:23 PM, Fred Sawyer fwsaw...@gmail.com wrote:

 I'm happy to say that the dates and hotel for the NASS conference have
 now been set!

 We will be meeting Aug. 22-25, 2013 in Boston/Cambridge, Massachusetts
 at the Courtyard by Marriott.  Full details are not yet available,
 since I am still finalizing the contract with the hotel (so please
 don't try to make a reservation yet!) - but the dates and location are
 definite.

 In a slight departure from our usual agenda, our 'tour day' on Aug. 23
 will omit the bus ride this year and will focus on two exhibits at
 Harvard - the primary one being the Time exhibit that Sara Schechner
 has mentioned on the Sundial List.  Harvard has the largest collection
 of sundials in North America, and many of them will be on view as part
 of the exhibit.  Sara, who is the curator of the collection, has also
 indicated that we may be able to schedule some special viewings and
 discussion of dials that are not in the exhibit.  Part of the exhibit
 will include walking directions to a few other dials on the Harvard
 campus - and to other Harvard museums with items of interest.  We are
 also looking into the possibility of a visit to the Harvard
 Observatory.

 Details will be available on our website and in The Compendium when
 they become available.  Plan to join us!

 Fred Sawyer
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Hurray of Oz !

[Bill Gottesman]

That is incredible Fabio.  How did you figure this out?

-Bill

On Wed, Jan 23, 2013 at 10:07 AM, Fabio nonvedolora 
fabio.sav...@nonvedolora.it wrote:

   Hi Kevin,

 the name is just right, I think to know what it was connected to:
 http://youtu.be/cwofR3J0Gh4

 ciao Fabio

 Fabio Savian
 fabio.sav...@nonvedolora.it
 Paderno Dugnano, Milano, Italy
 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2)

  *From:* Kevin Karney kar...@me.com
 *Sent:* Wednesday, January 23, 2013 1:50 PM
 *To:* Sundial list Sundial list sundial@uni-koeln.de
 *Subject:* Hurray of Oz !

 A rare engine from Australia circa 1930 2hp Sundial type B engine ….
 Best wishes
 Kevin

  --
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial


 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Wall declination

[Bill Gottesman]

Charles, for a simple and effective measure see Wall
Declination.pdfhttp://www.precisionsundials.com/wall%20declination.pdf
  and WallDeclination.exehttp://www.precisionsundials.com/walldeclination.exe.
 I do not know how its accuracy compares to other methods, but it is an
easy method to perform.
-Bill Gottesman

On Sat, Sep 22, 2012 at 7:36 AM, Charles Beck chforens...@gmail.com wrote:

 Hello all,
 My first post here, another sundial enthusiast.
 Doing my first sundial on a declining westerly wall.
 Can you share your tips to measure the wall's declination as accurately as
 possible?
 From a sat image I measured 10 degrees tilt.
 With the nail and board method I got 9.2 degrees as an average of a
 morning and afternoon measurement.
 Can I get more accurate?
 regards

 Ch.


 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: St. Margareth

[Bill Gottesman]

Thank you for sharing this dial.  It is a great example of the quiet
strength of simple design elements.  The blue background with white lines
and numbers is friendly to the eye and eye-catching at the same time.  The
symmetry of the annular dials surrounding the round stain glass windows is
very satisfying.  Bravo to the designer for keeping it understated and
without furniture.
-Bill

On Wed, Aug 1, 2012 at 4:39 AM, Reinhold Kriegler
reinhold.krieg...@gmx.dewrote:

 **

 Dear friends,

 ** **

 did you see already the “sundial of the month *August”* at Joël 
 Robic’ssplendid website on b
 **eh**alf of the Olympic Games…

 http://www.cadrans-solaires.fr/cadrans-Londres-saint-margareth.html 




 Regards,

 Reinhold Kriegler

 **
 **

 ** ** ***  * ** 

 *Reinhold R. Kriegler*

 *Lat. 53° 6' 52,6 Nord; Long. 8° 53' 52,3 
 Osthttp://www.ta-dip.de/sonnenuhren/meine-sonnenuhren.html
 **; 48 m ü. N.N. **
 *GMT +1 (DST +2)  *www.ta-dip.de*

 *http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html*http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html
 * *

 http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen.html
 

 ** **

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



image001.jpg---
https://lists.uni-koeln.de/mailman/listinfo/sundial

DeltaCad on a mac

[Bill Gottesman]

Hello Listers,

The delta cad website now says DeltaCad will run on the Mac operating
system.  Has anyone tried it out?

-Bill
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Sundial found in Jamestown excavation

[Bill Gottesman]

  
  
Fred's rediscovered Serle's dialing scale plays an important role in
this video. Fred, did the archeologists contact NASS for advice,
and did the scale come from you? The person demonstrating the scale
could have been a bit more careful to make sure the drawn dial lines
all intersected at the origin of the string-hole, but otherwise, the
scales did the trick!

-Bill

On 6/27/2012 1:07 PM, Fred Sawyer
  wrote:

An exciting find in the Jamestown excavation - a 17th
  century diptych dial.
  
  See the article at: 
  
  http://popular-archaeology.com/issue/june-2012/article/archaeologists-unearth-rare-17th-century-find-at-jamestown-excavations
  
  Be sure to view the video that shows the actual uncovering of the
  dial and the reverse engineering that determined the latitude for
  which it was made. Note that the dialing scale the archeologist
  is using is a NASS scale I provided to members many years ago at
  the first NASS conference. (BTW if you haven't yet sent in your
  registration for this year's conference in Asheville NC, please do
  it soon!) I believe the instructions he was using came from the
  Compendium article by Steve Woodbury.
  
  Fred Sawyer
  
  
  
  
  
  
  ---
https://lists.uni-koeln.de/mailman/listinfo/sundial





  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: The most exact sundial of the world In Samedan!

[Bill Gottesman]

  
  
Hello All,

I am a little confused: Who made this dial?
I think it is magnificent. The setting is stunning, the rock
mounting is dramatic. This is a first-class project.

I would be interested in reading (in English) how it was mounted,
how it was aligned, how it was engraved, how the discs are
mechanically assembled and what kind of bearings are used to
minimize play. I hope an article in the NASS Compendium, or the BSS
Journal is forthcoming.

Although the Renaissance double focusing dial can be read to
within 10 seconds, in practice it has mostly only been accurate
to within 1 minute, and sometimes worse. This is because the
Equation-of time is an average over the current 4 year cycle, and is
further due to imperfections in the roundness and concentricity of
the helix and imperfections in polar alignment. 

-Bill Gottesman

On 6/25/2012 3:55 PM, Frans W. Maes
  wrote:

Dear
  Fabio, Roger  all,
  
  
  It is always interesting and instructive to consider claims of
  extraordinary properties; in this case, a temporal accuracy of 10
  seconds. The final accuracy of a sundial is the result of several
  factors, among which the accuracy of orientation and mounting.
  
  
  However, the basic factor here is the accuracy with which a hair
  line can be placed in the exact center of a strip of light by
  rotating a disk. The attached photo nr. 7 from the following pdf,
  taken from Fabio's site:
  
  http://www.sundialatlas.eu/photo/CH/156/CH000220_2_A.pdf
  
  sets the stage. The slit (the gnomon) is placed at the center of
  rotation of the disk that carries the hair line.
  
  
  Ten seconds of time corresponds to a rotation of 2.5 minutes of
  arc around the polar axis. So the question is: can the hair line
  be placed on the theoretical center line of the light strip with
  an accuracy of 2.5 arcminutes? I think that only actual
  experiments can answer this question, but I am doubtful.
  
  
  The edges of the light strip are sharpest close to the gnomon, but
  the lateral displacement of the hair line due to rotation is small
  there. Further out (to the right in Fig. 7) the light strip gets
  wider, with fuzzier edges. What would be the best distance from
  the gnomon to look for estimating the center? And what accuracy
  would be feasible? Does anyone know about experimental data on
  such a task?
  
  
  As far as I know, the only case where a reading accuracy of 10
  seconds of time is achieved, is in the double focusing sundial of
  Bill Gottesman; see:
  
  http://www.precisionsundials.com/sundial_list.htm (scroll all the
  way down).
  
  
  Best regards,
  
  Frans Maes
  
  
  On 24-6-2012 20:09, Fabio nonvedolora wrote:
  
  On Sundial Atlas there is the card of this
sundial with 4 pdf files

  
  attached, one of them with technical info. All of them are in
  german.
  
  www.sundialatlas.eu/atlas.php?so=CH220


ciao Fabio


Fabio Savian

fabio.sav...@nonvedolora.it

Paderno Dugnano, Milano, Italy

45 34' 10'' N, 9 10' 9'' E, GMT+1 (DST +2)


From: Reinhold Kriegler

Sent: Sunday, June 24, 2012 4:39 PM

To: Sundial Mailingliste

Subject: The most exact sundial of the world In Samedan!


Dear friends! Have a look to Switzerland!


Genaueste Sonnenuhr der Welt steht im Engadin

Auf Muottas Muragl auf 2456 Meter ber Meer ist am Donnerstag
die genaueste Sonnenuhr der Welt eingeweiht worden.


 a..
http://www.bote.ch/vermischtes/genaueste-sonnenuhr-der-welt-steht-im-engadin

 Quelle: suedostschweiz.ch

 b.. Datum: 22.06.2012, 17:00 Uhr

 c.. Webcode: 39872


O I love the superlatives in connection with sundials!! :-)


So far this one I did not know: The most exact sundial of the
world!



Best regards


Reinhold Kriegler






* ** ***  * ** ***


Reinhold R. Kriegler


Lat. 53 6' 52,6" Nord; Long. 8 53' 52,3 Ost; 48 m . N.N.

GMT +1 (DST +2) www.ta-dip.de


http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html

http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen

Shadow Clock Kit

[Bill Gottesman]

Hello Sundials Listers,

This is not a sundial, but a kit for a clock that is kinda like a sundial -
it tells time with shadows.  How did we miss this?

http://evilmadscience.com/productsmenu/tinykitlist/156

I ordered mine today.

-Bill
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Shadow Clock Kit

[Bill Gottesman]

I am so ashamed. -Bill

On Wed, Jun 20, 2012 at 5:17 PM, Fred Sawyer fwsaw...@gmail.com wrote:

 Bill

 You need to read The Compendium more closely!  This kit was mentioned on
 p.40 in last September's issue.

 Fred


 On Wed, Jun 20, 2012 at 5:02 PM, Bill Gottesman billgottes...@comcast.net
  wrote:

 Hello Sundials Listers,

 This is not a sundial, but a kit for a clock that is kinda like a sundial
 - it tells time with shadows.  How did we miss this?

 http://evilmadscience.com/productsmenu/tinykitlist/156

 I ordered mine today.

 -Bill

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial




---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: New analemmatic

[Bill Gottesman]

What does the writing along the top and bottom of the dial say in english?
 -Bill

On Sat, Jun 16, 2012 at 4:26 AM, Perit Alexei Pace a...@onvol.net wrote:

 Dear all,

 An analemmatic sundial (humbly designed by the undersigned) has now been
 completed in the village of l-Għarb in Gozo (Malta).  We just need to
 indicate the monthly durations of June and December.

 Some images here:

 https://plus.google.com/u/0/114664468598779337464/posts/5hDzAE4eLUV
 https://plus.google.com/u/0/114664468598779337464/posts/TmXYYkxuy7Q
 https://plus.google.com/u/0/114664468598779337464/posts/RCAfvW5sn3X

 Best regards,

 Alexei


 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Transit of Venus

[Bill Gottesman]

Sara,

1) That is pretty original.
2) It won't be copied by anyone in our lifetime.

-Bill

Ken Launie, proposed to me between first and second contact of Venus on
the Sun as we shared an eyepiece
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Analemmatic in a public place

[Bill Gottesman]

Very nice.  -Bill

On Tue, May 15, 2012 at 4:15 PM, Mac Oglesby ogle...@sover.net wrote:


 Hello friends,

 Last Saturday I repainted the analemmatic sundial I installed a few years
 ago outside the west entrance to my town's Municipal Center. You can see
 the lower parts of the doors in the background. (The cones and tapes were
 removed on Sunday.)

 http://dl.dropbox.com/u/**3688834/**SundialOutsideMunicipalCenter.**pnghttp://dl.dropbox.com/u/3688834/SundialOutsideMunicipalCenter.png

 The Town Manager, the Police Chief, and the Town Highway Department were
 all very cooperative. All of them seemed quite pleased to have a sundial
 where scores of people would walk over it each day. On a nearby post are
 instructions for using the dial, including how to convert this sundial's
 time to clock time.

 For a view of the condition of one of the hour point labels before the
 repainting, look here:

 http://dl.dropbox.com/u/**3688834/HourPointElevenBefore.**pnghttp://dl.dropbox.com/u/3688834/HourPointElevenBefore.png

 The entire process, working alone and including vacuuming the pavement,
 took between 3 and 4 hours.

 I'm hoping that when the next refurbishing comes due there will some
 volunteers to help with the hands and knees part, at least.

 Fondest Regards,

 Mac Oglesby

 --**-
 https://lists.uni-koeln.de/**mailman/listinfo/sundialhttps://lists.uni-koeln.de/mailman/listinfo/sundial


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Cray Research 1984 Sun Dial

[Bill Gottesman]

  
  
I own one, from ebay. It is unique in that the numerals are in
binary. There are many chinese characters on the dial face, but I
do not know what they mean. I have photos if any one wants a stab
at deciphering them.
-Bill
On 4/26/2012 2:26 PM, J M wrote:
A friend of mine noticed this sundial on e-bay.
  
   http://www.ebay.com/itm/Cray-Research-1984-Sun-Dial-/300693750335?pt=LH_DefaultDomain_0hash=item4602be823f#ht_500wt_1105
  
  I got a clock or two over the years but never a sundial.
  
  I've never worked for Cray.
  Anyone familiar with this piece of Cray culture?
  
  -cheers
  
  
  
  
  
  ---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: How would this sundial work?

[Bill Gottesman]

There is more of a description of that dial at
http://www.diduknow.info/sun/san6.html#.  It is a horizontal dial of which
the gnomon has been broken off.  It is for use during daytime and at night.
 I presume the rotating plate allows adjustment for telling time by the
moon, depending where the moon is in its ~30 day synodic period.
-Bill

On Tue, Feb 14, 2012 at 9:25 AM, J. Tallman jtall...@artisanindustrials.com
 wrote:

 Hello All,

 ** **

 I came across a picture of a sundial this morning that I found to be
 confusing. See the dial picture on the following web page – it has a
 vertical post gnomon and the dial plate looks like it might be designed to
 rotate about the center:

 ** **

 http://www.diduknow.info/sun/san5.html#

 ** **

 Have any of you seen this dial before and do you have any ideas how it
 might work?

 ** **

 ** **

 Best,

 ** **

 Jim Tallman

 www.artisanindustrials.com

 jtall...@artisanindustrials.com

 ** **

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Sundials in cinema

[Bill Gottesman]

The dial and the trees show two shadows from different light sources.
 Would it give too much away to explain why that is?  -Bill

On Sun, Dec 18, 2011 at 5:36 PM, Darek Oczki dhar...@o2.pl wrote:

 Dear friends

 I've got two news for those interested in sundials in movies.

 1. In the very beginning of the latest movie by Lars von Trier
 (Melancholia) there is a nice scene shoving a close view of a horizontal
 sundial. Screenshot attached. Later it appears in the film several times
 more but only from a distance.

 2. There is an Indian movie comapany Sundial Pictures. They have an
 interesting sundial animation used as their motion logo. Follow the link
 below to watch it:

 http://sundialpictures.in/index.html

 --
 Best regards
 Darek Oczki
 52N 21E
 Warsaw, Poland

 GNOMONIKA.pl
 Sundials in Poland
 http://gnomonika.pl
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Christmas Greetings

[Bill Gottesman]

Very nice.  -Bill Gottesman

On Fri, Dec 16, 2011 at 7:57 AM, Kevin Karney ke...@karney.com wrote:

 Dear Fellow Gnonomists

 The comes with greetings from Elizabeth and myself for a very blessed
 Christmas and a wish for the sunniest of days in 2012.

 The attachment is an intrinsic representation of the Equation of Time. An
 intrinsic curve is one in which equal increments of abscissa are found
 along the curve itself (rather than along a fixed axis - as in a
 normal cartesian graph). Plotting a graph in this way allows it to be
 folded - thus making a compact, but easily readable pictogram. You may
 recall Fred Sawyer's paper (NASS Compendium 12 iii) on the Bury St Edmunds
 dial - which inspired this re-design.

 The curve is 'accurate' for noon UTC, but you may like a copy of the graph
 for noon in your particular Time Zone, incorporating the longitude
 correction. If you would like a copy, then e-mail me with….
 1) the name of your town/village
 2) your latitude and longitude in degrees and minutes
 3) the name of your time zone (e.g CET for Central European Time)
 4) your time zone offset in hours (e.g +1 for CET or -8 for PST)
 5) whether you print on A4 paper or US Letter
 The curves take me seconds to generate, if I get the info exactly in this
 format

 Best regards
 Kevin Karney
 Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
 51° 44' N 2° 41' W Zone 0
 + 44 1594 530 595


 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: paper sundial

[Bill Gottesman]

Fabio, these paper dials are wonderful!  What a great treat.  Thank you so
much.  -Bill Gottesman

On Thu, Dec 15, 2011 at 6:09 AM, Fabio nonvedolora 
fabio.sav...@nonvedolora.it wrote:

   Hi all, news from the clouds.

 I’ve a toy for the end of the year.
 I don’t think this is the very last end of the year, like some Maya
 supposed, and this is a great year, it is better than 2012 :-)  (like the
 same Maya didn’t know) so I hope you have fun with this new section of
 Sundial Atlas.

 You can reach ‘paper sundial’, a menu of Gnomolab, directly at this
 address: www.sundialatlas.eu/atlas.php?gnomolab=3
 You will find 4 models, this number is growing and if you have other
 models to propose, I’ll be happy to develop them in Gnomolab.

 The models may be setted for any coordinates and other features, you will
 get a pdf as replay.
 The 3rd model is designed to be applied to glass windows (you may found
 the declination of the windows with Gnomolab). It has a small gnomonic hole
 you can do with a pin or a small nail, moreover this model may be customed
 with a photo (or a logo). I uploaded some sample photos but anyone may
 upload other photos (public or for personal use).

 Have fun, ciao, Fabio

 Fabio Savian
 Paderno Dugnano, Milan, Italy
 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2)

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Bulgarian Sundial Design

[Bill Gottesman]

  
  
I have not seen this design before. I like it and I think the
public will too. I think it would be useful. -Bill

On 11/16/2011 3:46 AM, Mike Cowham wrote:

  
  
  
  Dear Sundial Friends,
  I have been in contact with a man, Boris Kostov,in Bulgaria
whose father has made what he believes to be a unique sundial.
He has tried to contact this mailing list but has so far been
unsuccessful, so has asked me to forward the information. See
attached pictures.
  Basically it is a fairly standard design of dial but the
innovation is to add the Equation of Time to the gnomon so that
when a finger is positioned such that its shadow falls on the
central line of the hour scale, it is pointing at today's figure
for EoT correction.
  He believes that this idea is new and solicits our opinions.
  
  If you have ever seen such a method before or wish to
comment, please contact Boris Kostov,silveriu...@yahoo.com
  
  Thanks in advance.
  Regards,
Mike Cowham.
  
  
  
  
  
  ---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Bulgarian Sundial Design

[Bill Gottesman]

  
  
I meant to add: How to handle the rapid change in EoT around the
solstices will be challenging. -Bill

On 11/16/2011 3:46 AM, Mike Cowham wrote:

  
  
  
  Dear Sundial Friends,
  I have been in contact with a man, Boris Kostov,in Bulgaria
whose father has made what he believes to be a unique sundial.
He has tried to contact this mailing list but has so far been
unsuccessful, so has asked me to forward the information. See
attached pictures.
  Basically it is a fairly standard design of dial but the
innovation is to add the Equation of Time to the gnomon so that
when a finger is positioned such that its shadow falls on the
central line of the hour scale, it is pointing at today's figure
for EoT correction.
  He believes that this idea is new and solicits our opinions.
  
  If you have ever seen such a method before or wish to
comment, please contact Boris Kostov,silveriu...@yahoo.com
  
  Thanks in advance.
  Regards,
Mike Cowham.
  
  
  
  
  
  ---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Earth rotations

[Bill Gottesman]

  
  
I think it is 366.25 rotations. The orbit around the sun accounts
for one additional axis rotation to the 365.25 day-to-day
rotations. Yes? No?
-Bill G

On 9/30/2011 11:41 AM, Marcelo wrote:
I think it's a little, a very little less than 365,25
  rotations. This "very little", accumulated through the centuries,
  has introduced an error in the seasons, which caused the Pope
  Gregory to correct the calendary in the 16th century. For all I
  know, the "very little" above is something like 3 days each 400
  years. 
  
  2011/9/30 Astrovisuals m...@astrovisuals.com.au

  

  
Heres an easy question:
How many times does the Earth rotate on its axis in
  a year (to the nearest quarter day)?
You can win lots of bets with your friends with the
  right answer!


  


* David
Widdowson, ASTROVISUALS
  

  

  
  
  ---
  https://lists.uni-koeln.de/mailman/listinfo/sundial
  
  

  
  
  
  
  
  ---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Fwd: Re: Question on a possible sundial.

[Bill Gottesman]

  
  
I agree that it is not likely to be a sundial.  I wonder what
markings are hidden under the flower bowl.  For example, this could
be an anniversary sundial, marking solar noon with a light beam on a
particular date.  Or maybe it is a type of compass aligned with the
celestial pole.  Or maybe a mirror floats in the bowl, and the user
looks down the tube, and their gaze is reflected up towards the pole
star.  It would be nice to know if there are markings under that
flower-pot!
-Bill

On 8/19/2011 3:19 PM, Frans W. Maes wrote:
Hi all,
  
  
  Thanks to the increased attachment size I can post the illustrated
  question of Duncan Meyers to the list, together with my initial
  response. Any additional suggestions regarding the nature of this
  object?
  
  
  Best regards,
  
  Frans Maes
  
  
   Original Message 
  
  Subject: Re: Question on a possible sundial.
  
  Date: Fri, 19 Aug 2011 08:49:21 -0700
  
  From: Duncan Meyers electr0magn...@msn.com
  
  To: f.w.m...@rug.nl
  
  
  Frans,
  
  
  Yes, you are more than welcome to post it to the mailing list and
  see if anyone else knows or has an idea..  My thought when first
  seeing this was that it would allow light into the tube and focus
  the light to a point which would then move along a line and would
  track not only the time but also the date as well. Yes, the tube
  has lenses inside that has a small image when looking through it.
  Kinda like looking through the end of a telescope and you see an
  image but it is really small and far away.
  
  
  I'm part of a solar spectrograph competition to design and build a
  spectrograph and was thinking about using this model as a setup
  design. So the light would pass through the tube and be reflected
  downward into the vertical tube where it would pass through a
  collimeter and then through the grating.
  
  
  But, thank you for your help. I look forward to seeing what your
  members have to say.
  
  
  Best regards,
  
  Duncan Meyers
  
  Connected by MOTOBLUR™ on T-Mobile
  
  
  -Original message-
  
  From: "Frans W. Maes" f.w.m...@rug.nl
  
  To: Duncan Meyers electr0magn...@msn.com
  
  Sent: Fri, Aug 19, 2011 03:14:40 PDT
  
  Subject: Re: Question on a possible sundial.
  
  
  Hello Duncan,
  
  
  It looks sundialish, but I don't think it is. If the tube is
  pointing at Polaris, it could have been part of a pole-style. But
  no ring with hour numbers, parallel to the equator, is present.
  Neither are there numbers on the rim of the flower bowl.
  
  
  In the old days a type of sundial was known as "noon cannon" (see
  attachment for an example). A lens focused the sun's rays on a
  small, loaded cannon at noon, which then fired. So the
  neighbourhood could synchronize their watches and clocks. But then
  it is necessary to adjust the tilt of the lens holder to the sun's
  noon altitude on that day. And I don't see such an adjustment
  here.
  
  
  What else could it have been? Does the tube have lenses at either
  end? Can the tube slide in the tube holder? If it is a monocular,
  one could perhaps observe enlarged flowers with insects on them or
  so. Or if the sun passes the point in the sky at which the tube is
  aiming (which would occur twice a year) a hot spot could set a
  piece of wood, paper or so on fire, or heat a cup of water.
  
  
  That reminds me of a sculpture with a similar function, the 'Solar
  Orbit Transit Station'. See my website, www.fransmaes.nl/sundials
  and choose "Related objects" in the main menu. It is the first
  thumbnail.
  
  
  Does this make any sense? If you like, I could post your question
  to the Sundial Mailing list, a forum of sundialists around the
  world.
  
  
  Best regards,
  
  Frans Maes
  
  
  
  On 17-8-2011 20:20, Duncan Meyers wrote:
  
  

Hi,


I looked through your site and other sites and can't seem to
figure

  
  out what this is. Do you know if it is an exotic sundial that uses
  a
  
  point of light instead of a shadow?
  
  

Duncan Meyers

503-933-6097

  
  
  
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Falling Tree

[Bill Gottesman]

I think quantum physicists Neils Bohr and Erwin Schrodinger would say 
there is no sound until it is observed.  But I don't understand this 
stuff all too well.

-Bill

On 8/10/2011 7:26 PM, Donald Christensen wrote:
If a tree falls in the forest where no one can hear it, does it make a 
sound?



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Azimuth calculation/Wall declination

[Bill Gottesman]

  
  
About 10 years ago I worked out a simple method to measure wall
declination using just a carpenter's square and an accurate watch. 
The methods is described here http://www.precisionsundials.com/wall%20declination.pdf,
and a simple windows program that does all the calculations for you
is here http://www.precisionsundials.com/walldeclination.exe. 
When I tested it out many years ago, I believe it gave results
repeatable at different times and on different days to a few tenths
of a degree.

-Bill

On 7/31/2011 9:57 AM, Andrew Theokas wrote:

  

  Fellow dialists:
   
  I am using the following well known formula to calculate
the sun’s azimuth for a particular time and location:
   
  Azimuth= tan-1    (sin
  H/(sin φ*cos H – cos φ*tanδ)
   
  where 
  H= Sun’s
hour angle
  φ= the latitude - 42.3 degrees
  δ is the sun’s declination -
  18.62 degrees
   
  The location
is in Boston, USA or 42.3 degrees N and 71.04 degrees west
   
  I am using
the azimuth-azimuth approach to find the declination of a
wall found here:
   
  http://www.mysundial.ca/tsp/wall_declination.html
   
  the time the
measurement was made was 11:18 am (daylight savings time is
in effect)
   
  I can easily
calculate that the azimuth with respect to the wall is 26.8
degrees.
   
  Here is the
problem: using two other independent methods I find that the
wall’s declination is 20 degrees East.
   
  So 26.8
degrees – Sun’s Azimuth should equal about twenty degrees.
   
  But, using
the above equation I cannot get an Azimuth value to work.
One place where I might be in error is the value of the Hour
angle which I compute to be about –16 degrees.
   
  But you can
also find the Hour Angle on line here at http://pveducation.org/pvcdrom/properties-of-sunlight/sun-position-calculator
   
  Where might
I be going wrong?
   
  Many thanks
for a reply!
   
  Andrew
Theokas
   
   

  
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: E o T diagram

[Bill Gottesman]

I do not know the answer to this question:

Looking at the intersections of the EoT and Mean Time curves in M. 
Garcia's diagram, is there any reason to conclude that the area of the 
intersections outside the mean time curve must equal the area of the 
intersections inside the mean time curve?  The areas look similar.


My initial hunch is no, but I do not see how to readily prove or 
disprove this.


-Bill

On 6/23/2011 1:27 PM, Miguel A. Garcia wrote:

https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsdzsp52i_AE#5621470247522825746


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Multignomon Sundial

[Bill Gottesman]

  
  
Fabio, these are really wonderful ideas. I would not have
understood your block dial idea if I had not learned about
shadowplane dials fom Mac Oglesby and, I believe, Fer de Vries.
-Bill

On 6/13/2011 8:31 AM, Fabio Savian wrote:

  
  
  
  ... or to get the shadows
  alignment without the hour line
  
  Fabio
  
  Fabio Savian
fabio.sav...@nonvedolora.it
Paderno Dugnano, Milan, Italy
45 34' 10'' N 9 10' 9'' E
GMT +1 (DST +2)
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Asking for advice, on starting-up a sundial business

[Bill Gottesman]

Hello David,

I make and sell sundials as a business-hobby, not a business per-se, so 
I may not be best suited to answer your question.  I sell about 4 
sundials per year, ranging from $1,800 to $8,000 each.  I also sell 
about 3 consults each year for sundial layouts at about $75 each.  I 
tell my consult-customers that they can download a program and do this 
for free, but I think they don't want to spend the time and would rather 
pay a little money.


I do not actively advertise other than a rudimentary website, because 
frankly I currently have all the business I want; I do this for a 
part-time hobby, not to make a living.


I am very fortunate to have built a good friendship with Kate Pond, a 
local sculptor who likes to make sun-oriented sculpture.  Working with 
someone who has the skills and interest in building things I would never 
attempt on my own has been very satisfying, and has enabled me to 
affiliate my name with some wonderful public and private projects.  I 
encourage you to seek out similar partnerships.  I read the NASS 
compendium and the BSS Bulletins religiously.  They give access to great 
ideas conceptually and aesthetically.  Please ask for permission and 
give proper credit if you use someone else's idea.  I am not qualified 
to advise on copyright and intellectual property, but issues may arise 
in this domain.


Initially, my customers were first degree relatives.  Now my customers 
are universities, private individuals, high-schools, botanical gardens, 
and museums, roughly in that order.  I have done some gratis work for 
one or two townships in advising and laying out a stone circle and an 
analemmatic dial.  I do not know how my customers find me, but I presume 
it is by finding my website on a google search.


I do not consider myself particularly business-savy.  I decided early on 
that I would try to sell a few well-made expensive sundials rather than 
deal with a lower cost / high volume model, as I did not have a knack 
for running the latter.  I also like the challenge of designing and 
building a technical piece that is an unusual addition to the family of 
sundials.


If I had to do this for a real living I am not sure what I would do to 
scale up.  I would probably try to get some free recognition via 
articles in gardening magazines.  I know William Andrewes got fantastic 
recognition for his sundials via an article in Smithsonian Magazine by 
Dava Sobel.


I think my best advice is to make a high quality product, and to educate 
your customers on what to expect from it (local vs civil time, daylight 
saving, etc.).  Artistically, I would hope you can develop your own 
recognizable style.  There is no mistaking a Spectra sundial, a Wenger 
sundial, or one of John Carmichael's carved stone dials, for example.  
Though those are all examples of custom dials, I am sure even if your 
product is a massed produced one, you can still make it look like an 
Andersson dial.


-Bill Gottesman
Precision Sundials LLC

Exactly a month ago, I asked for information or advice on starting a 
sundial

business - but only received one response to this List, and none privately.

I am not attempting to 'copy' any existing items, or designs - preferring to
develop my own, and using some limited market research which I have done.

Based on earlier information from Martina Addiscott in the UK, I am tempted
to concentrate on the Educational Sector - though I can see that Architects
or Landscapers may also be a good source of orders, for their own projects.

I was even thinking about metal-studs, for interactive 'analemmatic' layouts
on wooden garden decking - simple, cheap, plus adding value to properties.


Can anyone recommend the best type of information (and/or products) to sell,
plus where the largest 'customer-base' might be - like schools/gardens, so
that I could begin to think about this.  There are obviously lots of sundial
businesses in the world, and I like the idea of making money from my hobby!

Any appropriate information or suggestions, would be very much appreciated.


My regards to all,

David Andersson.

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: BSS Bulletin on DVD

[Bill Gottesman]

  
  
Sign me up, John! How do we pay? Can we use paypal?
-Bill G

On 3/11/2011 11:17 AM, JOHN DAVIS wrote:

  

  

  Dear Dialling Colleagues,
  
  The British Sundial Society is pleased to announce
that the full run of BSS Bulletins, from the start of
the Society in 1989 until September 2010 (a total of 75
issues) is now available on a DVD-R.
  
  The cost of the DVD to BSS members is 25 +pp.
It may also be purchased at a cost of 75 by
non-members, though it would be advantageous to join to
get the lower price! Contact BSS Sales (Elspeth Hill at
mem...@ehill80.fsnet.co.uk)
to purchase, or me for any technical enquiry. 
  
  The BSS is grateful to Kevin Karney, assisted by
Elaine Hyde, for the conversion of the 75 issues into
PDF files. 
  
  Regards,
  
  John
  ---

Dr J Davis
Flowton Dials

  

  
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Moscow sundial?

[Bill Gottesman]

That is Hilarious!  Maybe for nickle it can read your fortune, too!  
-Bill Gottesman


On 3/11/2011 4:56 PM, Willy Leenders wrote:

Maybe this helps: a bathroom weighting scale on a rail along the midline and the 
instruction on the scale, slide the scale until the date and read your weight and 
time
This suggestion is just to initiate a brainstorming session.

Willy Leenders
Hasselt in Flanders (Belgium)

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

A 14th century sundial question from France.

[Bill Gottesman]

Richard Kremer, the Dartmouth physics professor who brought the ~1773 
Dartmouth Sundial to display at the NASS convention this past summer, 
asked me the following question.  I have done a bit of modelling on it, 
and have not been able to supply a satisfactory answer.  Is anyone 
interested in offering any insight?  My hunch is that the astronomer who 
wrote this guessed at many of these numbers, and that they will be 
estimates at best for whatever model they are based on.  I have tried to 
fit them to antique, equal, and Babylonian hours, without success.  In 
1320, the equinoxes occured around March and Sept 14 by the Julian 
Calendar, as best I can tell, and that doesn't seem to help any.


-Bill
---
I've got a sundial geometry question for you and presume that either 
you, or someone you know, can sort it out for me.


A colleague has found a table of shadow lengths in a medieval 
astronomical table (about 1320 in Paris).  The table gives six sets of 
lengths, for 2-month intervals, and clearly refers to some kind of 
gnomon that is casting the shadows.  The manuscript containing this 
table of shadow lengths appears in a manuscript written by Paris around 
1320 by John of Murs, a leading Parisian astronomer.  I don't know 
whether Murs himself composed the table or whether he found it in some 
other source.  The question is, what kind of dial is this.  A simple 
vertical gnomon on a horizontal dial does not fit the data, which I give 
below.


 Dec-Jan
 hour 1 27 feet
 hour 2 17 feet
 hour 3 13 feet
 hour 4 10 feet
 hour 5 8 feet
 hour 6 [i.e., noon] 7 feet

 Nov-Feb
 1 26
 2 16
 3 12
 4 9
 5 7
 6 6

 Oct-Mar
 1 25
 2 15
 3 11
 4 8
 5 6
 6 5

 Sept-Apr
 1 24
 2 14
 3 10
 4 7
 5 5
 6 4

 Aug-May
 1 23
 2 13
 3 9
 4 6
 5 4
 6 3

 Jul-Jun
 1 22
 2 12
 3 8
 4 5
 5 3
 6 2

 Note that in each set, the shadow lengths decrease in identical 
intervals (-10, -4, -3, -2, -1).  This might suggest that the table is 
generated by some rule of thumb and not by exact geometrical 
calculation, for by first principles I would not expect these same 
decreasing intervals to be found in all six sets!


 I started playing with the noon shadow lengths at the solstices, 
looking for a gnomon arrangement that yields equal lengths of the gnomon 
for shadow lengths of 7 (Dec) and 2 (Jun) units.  If you assume the dial 
is horizontal and you tilt the gnomon toward the north by 55 degs, my 
math shows that you get a gnomon length of 2.16 units.  I assume that 
Paris latitude is 49 degs and the obliquity of the ecliptic is 23.5 degs 
(commonly used in middle ages).


 I'm too lazy to figure out the shadow lengths for the other hours of 
the day with a slanted gnomon, and presume that you have software that 
can easily do that.  Would you be willing to play around a bit with the 
above lengths and see if you can determine what gnomon arrangement might 
yield these data?  Perhaps the dial is vertical rather than horizontal?  
In any case, the data are symmetrical, so the gnomon must be in the 
plane of the meridian.


 Knowing that you like puzzles, I thought I'd pass this one on to you.  
If you don't have time for it, don't worry.  This is not the most 
important problem currently facing the history of astronomy!


 Best, Rich
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: altitude dial

[Bill Gottesman]

  
  
That is a very impressive both mathematically, and as an original
dial.
-Bill

On 1/25/2011 12:01 PM, Fabio Savian wrote:
hi Frank,
  
  two years ago I designed a variant of the shepherd's dial so it
  became universal (for any latitude).
  
  The moving gnomon is curved (the curve is an astroid) and it may
  move up and down and also around the dial.
  
  The gnomon (the tail of the rooster, the crest and the beak are
  decorative) has to be placed in the point where the curve of the
  date (the Sun declination curve) crosses the curve of the
  latitude. The upper shadow of the tail shows the time.
  
  
  ciao Fabio
  
  
  Fabio Savian
  
  fabio.sav...@nonvedolora.it
  
  Paderno Dugnano, Milan, Italy
  
  45 34' 10'' N 9 10' 9'' E
  
  GMT +1 (DST +2)
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Puzzle Photograph of the Eclipse - A complete guess

[Bill Gottesman]

This is just a conjecture:  I do not think this focused image of the 
eclipsed sun is a pin-hole artifact.  My guess is that it is a focused 
image by the lens, but is a 2nd or 3rd internal lens relfection.  In 
this manner, the image might be reversed, and its brightness greatly 
attenuated, so as to allow the sun appear to be displaced,  properly 
exposed, and in focus.


I don't see why the front surface of the lens would be hot.  My guess 
about the red glow is that it is a completely different internal 
reflection, and that the circular nature of it is defined by the 
circular edge of a lens component.  I think this would be analogous to a 
telescope's or  binocular's exit pupil.


-Bill

On 1/5/2011 2:54 AM, Frank King wrote:

Dear All,

A collegue pointed his iPhone at the
partially-eclipsed sun yesterday morning
and sent me the result:

   http://www.cl.cam.ac.uk/users/fhk1/Eclipse11.jpg

It is clear that the camera wasn't stopped
down anything like enough but why, he asks,
does he get a pin-hole artifact of the
eclipsed sun?

At this stage of the eclipse the crescent
was the other way round from the way it
appears in the artifact.  This is what one
would expect from an image created by a
pin-hole but not when printed and turned
the right way up!

Could this be an image of the reflection
in the water?

I know almost nothing about iPhone camera
technology and cannot give a convincing
explanation of the physics behind this
artifact.

There is also the surrounding elliptical
red background to explain.  Could that be
an image of the hot front surface of the
lens?

Any thoughts?

Frank King
Cambridge, U.K.

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Wonderful NREL Sun Position Calculator, in time for Solstice fun

[Bill Gottesman]

  
  
Hello Sundial-listers,

I used to rely on Luke Coletti's Great Circle website's GROK
calculator for a precise calculation of sun positions, but that page
has been non-operative for about a year now.

The National Renewable Energy Laboratory (NREL) in Golden Colorado
has provided an excellent resource at http://www.nrel.gov/midc/solpos/spa.html,
similar to GROK. Their MIDC Sun Position Algorithm utilizes Jean
Meeus' modified VSOP87 algorithm, reportedly accurate to 0.0003
degrees between years -2000 to +6000. The NREL site also provides
a link to an explanation of this algorithm as a pdf file
  http://www.nrel.gov/docs/fy08osti/34302.pdf.

The program will output a table of sun positions over a range of
dates, in as little as 1 second intervals. It allows many options
for sun position measurements, but the most helpful to me are
topocentric azimuth, geocentric sun declination, Topocentric
(uncorrected) sun elevation, and topocentric sun elevation corrected
for atmospheric refraction. These tables are essential to me in the
field when I delineate true north using a theodolite, and lay out
predictive sightings for sunrise and sunset.

Beware; if you select "Topocentric Zenith Angle", the results are
corrected for refraction, though they do not tell you this up
front. You must select "Topocentric (uncorrected) sun elevation" if
you want to exclude atmospheric refraction.

Lastly, they report the time of sunrise/sunset as when the center of
the sun is 0.8333 degrees below the horizon (uncorrected for
refraction). This is to account for the width of the sun, and an
average effect of refraction, and represents the moment that the
advancing or receding limb of the sun (not the sun's center) crests
the horizon.

-Bill
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: stop the earth: TI 59 PPX; No No Nooooooo!

[Bill Gottesman]

Summer solstice!  You lucky dog.  -Bill

On 12/13/2010 5:35 PM, John Pickard wrote:
Gee, I'm starting to sound like a grumpy old man. It must be the 
upcoming summer solstice. 

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: stop the earth: TI 59 PPX; No No Nooooooo!

[Bill Gottesman]

Roger, Roger, Roger,

Say it isn't so.  I had you figured as an HP 65 or HP 67 kind of guy.

-Bill

On 12/11/2010 1:53 PM, Roger Bailey wrote:

Hi Brent,

I found my old TI 59 PPX program to calculate the look up angle. To 
have a look at the math and the program steps go to this personal 
website folder. http://www3.telus.net/public/rtbailey/SML/ . There are 
two pdf files in this folder, 47 kb and 153 kb, too big to attach to 
this letter.


LookUpAmgle1 is three pages with diagrams and the mathematical steps. 
The diagrams help explain the mathematical steps.


LookUpAnglePPX is seven pages and includes the program steps and a 
couple examples. If anyone is really interested and still has a 
functioning TI 59, I will mail the little magnetic strip with the 
program on request.


Although this programmable calculator program was written 30 years 
ago, the math outlined is still valid. This could be rewritten to 
solve for your longitude and reprogrammed for modern use. I expect 
there are many examples available on the web.


Regards,
Roger Bailey
Walking Shadow Designs

--
From: Brent bren...@verizon.net
Sent: Friday, December 10, 2010 6:22 PM
To: Sundial List sund...@rrz.uni-koeln.de
Subject: re: stop the earth


I was playing with satellite look angle calculator today.

http://www.intelsat.com/resources/satellitedata-pas/calc-look-angle.asp

You chose the satellite you want to work with and then plug in your 
latitude and longitude and it will calculate the azimuth and 
elevation for you.


I think the math behind this program would work for my navigation if 
we could run it backwards.
Input the satellite I was looking at, input the azimuth and the 
elevation at the location and then the calculator would return with 
latitude and longitude.


Do you think this would work?

Does anyone know the math behind these calculators?

Thanks again;
brent

---
https://lists.uni-koeln.de/mailman/listinfo/sundial


---
https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: What can be calculated with a sun dial?

[Bill Gottesman]

  
  
A few extra:
  The stereographic projection, as used by Oughtred, allows
  calculation of the sun's altitude and azimuth at any (day)time on
  any date, and conversely, the calculation for which date and time
  the sun is at a specific azimuth and altitude. The stereographic
  and the orthographic (analemmatic dials) projections allow
  calculation of the time and azimuth of sunrise/sunset on any given
  date. Capuchin altitude dials allow instant calculation of the time of
  sunrise/sunset at any given date (Alessandro Gunella
showed how capuchin dials are derived from an orthographic
projection in the NASS compendium, June 2008). 
  
  Some dials also calculate equal-hours. Islamic dials have a
  Quibla line pointing to Mecca.
And Hendrik
  Hollander's sundial pint glasses tell when to start drinking!
  
I am curious to
  learn in what manner a sundial calculates the earth's
  eccentricity, aphelion and perihelion.
  
  -Bill

On 11/16/2010 4:38 PM, Jos Kint wrote:

  
  
  
  Dear sun dialists,
  
  What can be calculated with a
  good sun dial? Here is a list of 19 topics. Can you add some
  more items?
  1. The hour of the day
  2. The day of the year.
  3. The solar altitude.
  4. The solar azimuth.
  5. The longitude of the sun dial.
  6. The latitude of the sun dial.
  7. The moment of the equinoxes
  8. The moment of the solstices.
  9. The length of the tropical
  year
  10. The equation of time 
  11. The excentricity of the earth
  orbital around the sun.
  12. The obliquity of the eclips
  13. A compass function
  14. The declination of the sun.
  15. The moment of the perihelion
  16. The moment of the aphelion
  17. The moment of the next sun
  set
  18. The Babylonic time
  19. The Italian time
  
  
  Jos Kint

  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Burt Astronomical Compass (was Mechanically Complex Solar Compass on sale at auction)

[Bill Gottesman]

  
  
Thank you, John. The brochure is many pages long, with much
description to calibration. It sounds like it was a serious
precision instrument in its day. -Bill

On 11/4/2010 9:00 PM, John Pickard wrote:

  
  
  
  Good morning Bill,
  
  The compass is a Burt Astronomical Compass invented by
William Austin Burt in 1855 or thereabouts. 
  
  Burt described its function and use in some detail.
  
  Burt, William A. (1881) A key to the solar compass, and
surveyor's companion; comprising all the rules necessary for use
in the field. Also, description of the linear surveys, and
public land system of the United States; notes on the barometer,
suggestions for an outfit for a survey of four months, etc.,
etc. New York, D. Van Nostrand. 5th edition. (Facsimile reprint
by Carben Surveying Reprints)
  
  There is also some more information in his biography
  
  Burt, John S. 1985 They left their mark. William Austin Burt
and his sons, surveyors of the public domain. Landmark
Enterprises, Rancho Cordova.
  
  
  The "Key to the solar compass" is available as a free
download from Internet Archive (a wonderful source of all sorts
of old books and journals). Different editions are at the
following URLs
  
  http://www.archive.org/details/keytosolarcompas00burtrich
  
  http://www.archive.org/details/akeytosolarcomp00burtgoog
  
  http://www.archive.org/details/akeytosolarcomp01burtgoog
  
  
  
  Cheers, John
  
  John Pickard
john.pick...@bigpond.com
  
  
  In cold, overcast and rainy Sydney. Where has spring gone?
  

  
- Original Message - 
From: Bill Gottesman 
To: Sundial Mailing List

Sent: Thursday, November
  04, 2010 1:04 PM
Subject: Mechanically
  Complex Solar Compass on sale at auction


I saw (on-line) this interesting sun compass for sale by auction
this coming November 20th. I have not seen anything like it.
Other scientific instruments, clocks, sundials for sale at same
auction. I doubt I will bid on it.
-Bill

http://www.skinnerinc.com/asp/fullcatalogue.asp?salelot=2527M363+refno=++874110

Lot 363 
  Brass Solar Compass by W.  L. E. Gurley, Troy, New
  York, the brass instrument with Burt's solar attachment,
  horizontal circle read by opposing verniers, blued steel
  needle and scale calibrated 0-15 in two segments and engraved
  W.  L. E. Gurley, Troy, NY, silvered vertical half
  circle arc graduated to 30 minutes with vernier scale and
  sighting mounts, silvered declination and hour calibrated
  arcs, dual spirit levels, graduated sighting vanes and thumb
  screw leveling tripod attachment, ht. 14 in. 
  Estimate $2,000-4,000 

 
 ---
https://lists.uni-koeln.de/mailman/listinfo/sundial

  
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Mechanically Complex Solar Compass on sale at auction

[Bill Gottesman]

  
  
I saw (on-line) this interesting sun compass for sale by auction
this coming November 20th. I have not seen anything like it. Other
scientific instruments, clocks, sundials for sale at same auction.
I doubt I will bid on it.
-Bill

http://www.skinnerinc.com/asp/fullcatalogue.asp?salelot=2527M363+refno=++874110

Lot 363 
  Brass Solar Compass by W.  L. E. Gurley, Troy, New
  York, the brass instrument with Burt's solar attachment,
  horizontal circle read by opposing verniers, blued steel needle
  and scale calibrated 0-15 in two segments and engraved W.
 L. E. Gurley, Troy, NY, silvered vertical half circle
  arc graduated to 30 minutes with vernier scale and sighting
  mounts, silvered declination and hour calibrated arcs, dual spirit
  levels, graduated sighting vanes and thumb screw leveling tripod
  attachment, ht. 14 in. 
  Estimate $2,000-4,000 

  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Sad news for the Sundial Community

[Bill Gottesman]

  I learned from JD Gard's website for the ATEN sundials that David 
(Gard?), the inventor of the Aten heliochronometer, has died.

I do not know if the company will still sell the sundial.

I own one of the models, and it is a favorite to show guests.  It is 
readable to better than 1 minute.  I did not know Dave, but I certainly 
admired his originality and skill in manufacturing.

It is worth noting that craftsfolk are mortal, and often their art 
disappears with them.  When I see a dial I like and can afford, I 
generally buy it sooner rather than later.  You never know when someone 
will stop making a dial, whether by choice or not.

-Bill
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: A new look at the Equation of Time

[Bill Gottesman]

  
  
Very nice Kevin. Thank you sharing this.
-Bill

On 9/28/2010 9:05 AM, Kevin Karney wrote:
Dear Colleagues
  
You may be interested in the attached chart of the Equation of
Time for 2011. It is of interest for a number of reasons...
- it
is an 'intrinsic' plot - not thefamiliar cartesian, polar or
analemmatic form.
 An
  intrinsic plot has equal increments of the
  independentvariable along the curve of the plot rather than
  along the x-axis.
 This
  allows the curveto be folded - making a very compact form.
  - it
  is much easier to read than a normal plot, because the day
  points are all equally spaced along the curve.
  - it
  looks good !


  
  
  
  
  

  

The use of an intrinsic plot for the equation of time was
  first used in the Bury St Edmunds dial in the 1860s. SeeF.
  Sawyer: The Bury St Edmunds
  Curve,NASS Compendium12(3), p.29(Sept 2005)or John
  Davies: 'More on the Equation of Time on Sundials', BSS Bull
  17(ii), p.75 (June 2005).
This particular 'Flame' form is one of many possible
  compact folded forms that can easily be generated with a
  spreadsheet.
  
  For the number-obsessed, the chart is very precise. Though you
  cannot of course read it on the chart, the values of EoT are
  exact to within afraction of a second, since I have used the
  2011 polynomial algorithms issued to surveyors and
  navigatorsby HM Nautical Almanac Office. Thechart is for
  noon UT. If anyone would like a copy - correct for their own
  time zone and longitude - please let me know. Or if you are
  familiar withExcel, you can download the spreadsheet used to
  draw the curve from http://www.precisedirections.co.uk/Sundials/Index.html.
  The file is called "Almanac 2010_2011.xls". This has all the
  polynomial coefficients for the Sun and navigational stars for
  both 2010 and 2011.You can see a number of other intrinsic
  plots of the EoT at the above website. Click on the
  'Grange-over-Sands Conference' link.


For the really observant, you will notice a tiny additional
  gap between 31 Dec and 1st Jan: that is there because there
  are 365 1/4 days in a year not 365...


The zodiac signs on the chart mark the day starting the
  astronomical constellations when the Sun's longitude are
  passes 30, 60, 90 degrees etc. This may not conform with the
  astrological dates.


Best regards
Kevin




  
  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  

---
https://lists.uni-koeln.de/mailman/listinfo/sundial