Re: Does this type of dial have a name?

[John Davis via sundial]

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Hi Peter,

A descriptive name which is sometimes attached to dials like this is 
'analemmic', i.e. it has analemmas instead of hour lines but it is not 
an analemmatic dial.



Regards,

John
--
-- Original Message --
From: "Peter Mayer" 
To: "Sundial List" 
Sent: Monday, 16 Aug, 21 At 06:00
Subject: Does this type of dial have a name?

Hi,
A friend recently returned from Port Augusta and sent me photos 
of a dial in the Australian Arid Lands Botanic Garden 
(attached). The Garden describes it as a 'Projection Dial', but 
clearly that isn't a unique name for this form of sundial with 
EOT corrections for each hour. The earliest example I've seen 
described is the vertical dial by Père Ildephonse at the Convent 
Cimiez-Sur-Nice (the illustration is from Cousins' Sundials 
which dates from c. 1876. Is this the earliest example of such a 
dial? And, again: does it have a unique name?

best wishes,
Peter
  -- ---Peter MayerDepartment of Politics & 
International Relations (POLIR)School of Social 
Scienceshttp://www.arts.adelaide.edu.au/polis/ 
 The University of Adelaide, 
AUSTRALIA 5005Ph : +61 8 8313 5609Fax : +61 8 8313 3443e-mail: 
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Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/ 



BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/ 





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[John Davis via sundial]

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DearAndré,

I think the articles to which you refer were published in some of the 
early issues of the NASS Compendium, and not the BSS Bulletin.


Regards,

John


-- Original Message --
From: "André Reekmqns" 
To: sundial@uni-koeln.de
Sent: Saturday, 8 Aug, 20 At 17:59
Subject: request

Looking for the 3 pages article published in BSS or NASS 10 years? about 
rectifying a misaligned pole-style horizontal or vertical sundial.


André Reekmans
Sundial Society of Flanders, Belgium.

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Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/ 



BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/ 





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[John Davis via sundial]

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Hi Sara, Ross et al,

My understanding is that a seasonal (or unequal) hour is a period of 
time ('in the first hour' etc) and not an instant. It is never divided 
up into minutes and so the time of 6 minutes after dawn must be 
referring to a time in equal hours, most probably measured with an 
astrolabe as you suggest.


Regards,

John
---

-- Original Message --
From: "Schechner, Sara" 
To: "Ross Sinclair Caldwell" 
Cc: "'sundial list sundials'" 
Sent: Tuesday, 30 Jun, 20 At 21:20
Subject: RE: Time problem


In short, I am researching the biography of Filippo Maria Visconti 
(1392-1447), duke of Milan, and you probably know that these Italian 
princes  relied heavily on astrology. So, Visconti's time of birth 
is known precisely - "six minutes after sunrise," Monday, 23 
September, 1392. His natal chart was of course produced and 
interpreted, but it has been lost. I am trying to recreate it as it 
might have  been done by a court astrologer of the time.<<<


I have some thoughts about ascertaining the time of “6 minutes after 
sunrise” in 1392 in Milan.


First of all, Milan is one of the earliest towns to have a public tower 
clock in the 14th century, but it would only strike and show hours 
according to local solar time.  It would not be divided into  minutes. 
It was not reliable enough for such a horological chart.


Sundials would be the more commonly used timepiece, but the six-minutes 
is an unusual amount of precision.  My guess is that the court 
astronomer was using an astrolabe, which can be divided into units in 
the range  of 4-6 minutes.  Many also had arcs for the astrological 
houses and for both equal and unequal hours.  The actual time might have 
been taken from a bright star still visible in the dawn.


It is also worth considering what this 6-minutes after dawn really 
means.  Is the astrologer using unequal hours which were still more 
common in these early days of clocks?  If so, then six minutes would be 
equal  to 1/10 of the first hour on that day of the year—i.e., 1/10 of 
1/12 of the length of daylight.


Lastly, in reconstructing a horoscope, one needs to know the position of 
the planets to place them on the chart.  Some might be observed, but 
mostly they are taken from a table.  These varied in different 
manuscript  traditions.  Do we have a clue what table the astrologer was 
using?


Good luck with your project.

Sara

Sara J. Schechner, Ph.D.
David P. Wheatland Curator of the Collection of Historical Scientific 
Instruments

Lecturer on the History of Science
Department of the History of Science, Harvard University
Science Center 251c, 1 Oxford Street, Cambridge, MA 02138
Tel: 617-496-9542   |   Fax: 617-495-3344
sche...@fas.harvard.edu    | 
@SaraSchechner
http://scholar.harvard.edu/saraschechner 


http://chsi.harvard.edu/ 



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[John Davis via sundial]

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Dear Frans,

The picture that Dan-George pointed us to is excellent and intriguing too. My 
reading of the lettering is slightly different from yours. Starting from the 
top (presumably the winter solstice), I get 

X  I  M  E  P  I  N  H
   H  M  E  P  I  N  H
   E  P   IN H

where the columns represent the spaces between the hour lines. There could be 
some misreadings here. It is clearly not the standard Greek system of using the 
first letters of their alphabet as numbers but I don’t recognise the names of 
the seasons either. Looking through Sharon Gibbs’ book, I couldn’t find a 
similar set of inscriptions. Can any classical scholars help us?

As a second point, the front face of the marble looks to be vertical in the 
photo but I found another view online which seems to show it cut back at an 
oblique angle. Both forms of dial are known - which is this?

Regards,

John 
—
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


> On 8 Apr 2020, at 18:37, Maes, F.W.  wrote:
> 
> Dan-George, thank you for the link! That is a beautiful ancient scaphe dial.
> The article says: "The sundial features ... Greek names of seasons". I can 
> read a number of characters, which at all three date lines (equinox and 
> solstices) seem to include MEPINH. What season names are these?
> 
> Keep healthy!
> Frans Maes
> 
>> On Tue, Apr 7, 2020 at 12:33 PM Roser Raluy  wrote:
>> Thank you, it looks great!
>> Roser Raluy
>> 
>> Missatge de Dan-George Uza  del dia dt., 7 d’abr. 
>> 2020 a les 10:12:
>>> Hello, I've just read about the discovery of an antique sundial in Turkey.
>>> 
>>> https://www.dailysabah.com/life/history/2000-year-old-sundial-unearthed-in-southern-turkeys-denizli
>>> 
>>> Best regards,
>>> 
>>> -- 
>>> Dan-George Uza
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>> 
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
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> ---
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[John Davis via sundial]

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Dear Frans,

The picture that Dan-George pointed us to is excellent and intriguing too. My 
reading of the lettering is slightly different from yours. Starting from the 
top (presumably the winter solstice), I get 

X  I  M  E  P  I  N  H
   H  M  E  P  I  N  H
   E  P   IN H

where the columns represent the spaces between the hour lines. There could be 
some misreadings here. It is clearly not the standard Greek system of using the 
first letters of their alphabet as numbers but I don’t recognise the names of 
the seasons either. Looking through Sharon Gibbs’ book, I couldn’t find a 
similar set of inscriptions. Can any classical scholars help us?

As a second point, the front face of the marble looks to be vertical in the 
photo but I found another view online which seems to show it cut back at an 
oblique angle. Both forms of dial are known - which is this?

Regards,

John 
—
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


> On 8 Apr 2020, at 18:37, Maes, F.W.  wrote:
> 
> Dan-George, thank you for the link! That is a beautiful ancient scaphe dial.
> The article says: "The sundial features ... Greek names of seasons". I can 
> read a number of characters, which at all three date lines (equinox and 
> solstices) seem to include MEPINH. What season names are these?
> 
> Keep healthy!
> Frans Maes
> 
>> On Tue, Apr 7, 2020 at 12:33 PM Roser Raluy  wrote:
>> Thank you, it looks great!
>> Roser Raluy
>> 
>> Missatge de Dan-George Uza  del dia dt., 7 d’abr. 
>> 2020 a les 10:12:
>>> Hello, I've just read about the discovery of an antique sundial in Turkey.
>>> 
>>> https://www.dailysabah.com/life/history/2000-year-old-sundial-unearthed-in-southern-turkeys-denizli
>>> 
>>> Best regards,
>>> 
>>> -- 
>>> Dan-George Uza
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>> 
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> 
> ---
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[John Davis via sundial]

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Hi Peter,
For a mathematical and practical analysis, see 
Ortwin Feustel, 'Ivory Sundials of Nuremberg Incorporating a Scaphe Sundial' 
BSS Bulletin 24(ii) 36-42.
Regards,
John
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/
 

On Tuesday, 7 April 2020, 12:07:28 BST, Peter Mayer 
 wrote:  
 
   
Hi, 
   Dan-George Uza's recent post reminded me of a question I have. I was looking 
at Mark Lennox-Boyd's lovely Sundials the other day, especially photos of some 
of the beautiful Renaissance ivory diptychs, and realised that I didn't 
understand the principles behind the small scaphes on many dials. (Here's a 
Wikicommons photo of a Leonhard Miller dial). 
 The Greek and Roman scaphes, like the one in Dan-George's photo, were hollow 
sections of either spheres or cones, with a gnomon at their centre. Their mode 
of operation seems quite straight-forward.
 But the scaphes in diptyches weren't like that. They appear to be tiny slices 
of much larger spheres. And the gnomons are, of course, far from the centre. 
The 'furniture' on several of them seems similar to stereographic projections. 
But, since instrument-makers then were well able to make astrolabes with 
stereographs, perhaps not.
 So: can someone point me to an article which discusses these small scaphes? 
Or, in the meantime, help me understand how and why they were used? Why don't 
we make them any more? Or: are there any contemporary examples, using, say, 
bowls, or bird-baths or skateboard parks?
 best wishes,
 
 Peter
 
 ---
Peter Mayer
Department of Politics & International Relations (POLIR)
School of Social Sciences
http://www.arts.adelaide.edu.au/polis/
The University of Adelaide, AUSTRALIA 5005
Ph : +61 8 8313 5609
Fax : +61 8 8313 3443
e-mail: peter.ma...@adelaide.edu.au
CRICOS Provider Number 00123M
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[John Davis via sundial]

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Hi Steve et al,
The BSS Glossary has a separate term for dials which aren't the classic 
elliptical analemmatic type that we understand but does use an analemma in some 
form. We call these 'analemmic' which covers conventional dials with analemmas 
drawn on their hour-lines, dials with gnomons shaped like an analemma, and so 
on. We would encourage others, including the writer(s) of the Wikipedia piece, 
to use this term!
Regards,
John-
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/
 

On Saturday, 1 June 2019, 00:20:02 BST, Steve Lelievre 
 wrote:  
 
  
  Thank you to Joel, Fabio, and Bill. 
  Before I sent off my inquiry last night, I had got as far as deciding the 
dial must be some kind of Foster-Lambert similar to the Herstmonceux dial that 
Fabio mentioned, but I was still confused. I'm relieve to learn that it's not 
related to an analemmatic dial at all, and Wikipedia is simply wrong!
  
  Steve
  
  
 On 2019-05-31 5:14 a.m., Bill Gottesman wrote:
  
 
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  
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[John Davis via sundial]

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Hi Frans et al,
Polarizing sundials have featured a number of times in the BSS Bulletin. In the 
same issue (21(i), March 2009) as the article by the sadly-missed Allan Mills 
that Mike Isaacs pointed to earlier, Allan had a second article, pp. 14-16, on 
"An Electronic Polarization Sundial and Photometer" which shows background 
experiments on the physics that Wheatstone's device is based on. The first of 
these articles was one of the earliest we printed in colour, essential to see 
the proper effect of Allan's dial.
Earlier articles in the Bulletin are by Allan Mills again ("The Sellotape 
Sundial" 98(1) 3-9) and by David Colchester "A polarized light sundial" 96(3) 
13-15.
I think reading these articles will fully explain Wheatstone's device, of which 
several were evidently made.
Regards,
John--
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/
 

On Tuesday, 21 May 2019, 21:06:52 BST, 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
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Dear Dialling colleagues,
The term in the BSS Glossary for a "gnomic hole" is an 'oculus" (from the Latin 
for 'eye, of course).
Regards,
John
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/
 

On Wednesday, 13 March 2019, 12:29:58 GMT, Frank King  
wrote:  
 
 Dear All,

I have a mild distaste for "correction" since
it implies something is wrong.  In particular
'local mean time' and 'local mean time-zone time'
are both correct, but different, times.  One is
offset from the other but this offset is in no
sense a correction!

To me "offset" is neutral.

There are, of course, many many different
times in current use.  Here are just a few:

  TAI, UTC, UT1, UT2, GMT, GST, GPS time

None of these is wrong but each is offset
from all the others.

Sometimes the offset is constant such as
the difference between TAI and GPS time

Sometimes the offset changes infrequently,
such as the difference between TAI and UTC
(which changes only when there is a leap
second).

Sometimes the offset changes continuously,
such as the difference between GST (sidereal
time) and GMT.

This suggests that the word 'constant' is
not generally appropriate and is why I am
not keen on the Italian "costante locale".

This is actually a false assertion when
referring to local mean time versus local
time-zone time because in most places the
reference time zone is shifted 15 degrees
backwards and forwards at the whim of
legislators!  The offset is not constant!

Dan-George asks:

  how would you translate the Italian
  "foro gnomonico"

In English, this translates literally as
"gnomonic hole" but this would be a bad
translation!  It generally refers to the
hole in the roof (or possibly a side wall)
of a cathedral or large church that lets
in the sun so as to cast an image of the
sun on the floor.

The best English equivalent is "aperture
nodus" but that isn't quite the same thing.
An aperture nodus provides a spot of light
on the dial plate, not an image of the sun.

The French "oeilleton" is more challenging!
In English, this translates literally as
"eye-cap" which I think of as something
for medical use, for washing your eyes.

I rather suspect that the French also use
this to mean aperture nodus but I should
like confirmation.

Frank 

Frank King
Cambridge, U.K.

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Hi Frank,
Bravo - two quarters of a double horizontal dial!
Regards,
John---
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/
 

On Thursday, 3 January 2019, 12:49:00 GMT, Frank King  
wrote:  
 
 Dear All,

I have a simple rule with my puzzles: wait for a reply from Geoff Thurston and 
then reveal all.  The time has come!

In the recent spate of messages, both Bill Gottesman and Steve Lelievre were 
very close.  Bill is the only person to suggest an azimuthal dial with  
vertical styles (which describes my design) but Steve's drawing (despite the 
polar styles) is remarkably close to my design too.

The 'unusual space' is "The End-Flap of a Book" - not easy to guess!

By arranging for the top and bottom edges of the front cover to serve as 
vertical gnomons, you can mark out an azimuthal dial on the end-flap.  This 
way the user doesn't need to supply a gnomon, nor is there any need for any 
kind of pop-out gnomon.

The sundial is shown in operation outdoors in the real sun at:

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

This shows what the design looks like.  There are many forms of azimuthal dial 
but, as one who enjoys astrolabes, I like stereographic projections.  [OK, I 
do realise that my design uses the zenith as the centre of the projection and 
not the NCP!]

In terms of 'looking good', this design hardly competes with the Nuremburg or 
Harvard dials or the dials in the stunning images that Sara has just sent us.  
We can all look forward to the Adler catalogue.  Sadly, those dials look a bit 
expensive.

The link above shows the upmarket version of my design and this costs 15 GBP 
but you do get a book bundled in at no extra charge!  There are lots of pretty 
pictures of sundials inside.

What about implementing the design for less than a dime?

Well, a dime is about what it costs me to print out a sheet of paper, and all 
you have to do is to print out the following:

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

This is intended for A4-paper.  You may have to trim the edges if you use 
LETTER size.

This shows what is hidden on the inside back cover of the book.  That is where 
the early morning and late evening summer-time hours are found.

All you have to do is to fold along the black straight line (a valley fold not 
a ridge fold), place the S-part flat on a horizontal table, and point the S to 
SOUTH [some users find this a bit surprising!]. You must arrange for the 
larger part to be perpendicular to the S-part.

In summer, in the early morning and late afternoon, you have to place the 
larger part flat on the table; the edges of the S-part then serve as gnomons.

This really is a working diptych sundial and they don't come any cheaper!

Sadly it is designed for my latitude +52d 12m but anyone who has read this far 
is likely to be well equipped to adapt the design for another latitude.
 
Adventurous readers can add the appropriate wiggles to the hour lines to deal 
with longitude offset and EoT.  Maybe it would be best to design two such 
dials (one on each side of the paper), with December to June hour lines on one 
side and June to December hour lines on the other.

In the unlikely event that you might want the up-market version (with book 
attached) please contact:

  Hallam Kindersley 

Very best wishes

Frank




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[John Davis via sundial]

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Hi Steve,

The obvious early source for bird gnomons is the Butterfield style of portable 
dials.

In England, the most common animal supporter is a dolphin or stylised fish.

Regards,

John
—-
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


> On 30 Oct 2018, at 18:24, Steve Lelievre  
> wrote:
> 
> Hello,
> 
> Gnomons on horizontal dials are mostly either undecorated triangles, or have 
> simple polygonal or sigmoidal fretwork. However, recently I realized that the 
> next most common form I encounter is a gnomon carved with the shape or 
> silhouette of a bird. For example:
> 
> http://sundials.org/images/NASS_Registry/Dial_334/334_md_towson_hampton_2a.jpg
> 
> http://sundials.org/images/NASS_Registry/Dial_325/325_md_baltimore_clyburn_1.jpg
>  (using a small stick to replace the missing filament that formed the style)
> 
> http://sundials.org/images/NASS_Registry/Dial_920/920_bc_vancouver_knox_church-2a.jpg
> 
> Is it coincidence that I encounter these designs relatively often? Or, is 
> there some tradition of using bird motifs on sundials? If so, how did it 
> originate and what do they symbolize?
> 
> Steve
> 
> 
> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
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[no subject]

[John Davis via sundial]

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Only on flat planes, not inside scaphes

J

Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


> On 10 Aug 2018, at 22:38, Michael Ossipoff  wrote:
> 
> Sara and John--
> 
> But it's said that the hour-lines for Babylonian, Italian, and co-Italian 
> hours are straight lines, as they are on all the other dials that I've seen 
> that have Babylonian &/or Italian hours.
> 
> Michael Ossipoff
> 
>> On Fri, Aug 10, 2018 at 4:37 PM, Schechner, Sara  
>> wrote:
>> I am camping at Stellafane with little connection, so will keep this brief 
>> until I return to civilization!  
>> 
>> The gnomon is adjustable for different latitudes.  The choice determines the 
>> correct horizontal scale to use around the compass.  The 2 pin gnomon scaphe 
>> sundial are for finding Italian and Babylonian (or Nuremberg hours).  The 
>> instrument with the spinning pointer is a wind vane.
>> The instrument is made in Nuremberg in the early 17th century.
>> 
>> Sara
>> 
>> Sent from my iPhone
>> 
>> On Aug 10, 2018, at 12:48 PM, Michael Ossipoff  
>> wrote:
>> 
>>> Yes, the Boy Scouts of America at least used to sell a Compass-Oriented 
>>> Dyptich dial with several concentric rings, each having different 
>>> hour-lines, and with its string-gnomon adjustable for latitude, with 
>>> several attachment-points on the vertical surface. I think it accommodated 
>>> 3 latitudes. The hour-line rings were rectangular, it seems to me.
>>> 
>>> Someone at this forum designed a universal Horizontal-Dial whose hour lines 
>>> were curved lines originating from the gnomon-string's base-attrachment, 
>>> with latitude-labeled concentric circles telling where to read the hour 
>>> lines for the various latitudes.  ...and of course with the string-gnomon 
>>> slidable in a vertical slot in the vertical surface.
>>> 
>>> Michael Ossipoff
>>> 
>>> 
>>> 
 On Fri, Aug 10, 2018 at 4:22 AM, Dan-George Uza  
 wrote:
 Dear all,
 
 I've recently found this piece in a museum near me and I need your help in 
 dating it. 
 
 Why are the hour marks offset? I suspect a correction for latitude. And 
 what do the two small circular dials on the bottom measure?
 
 Also what would be the purpose of the circular shape containing the 
 alidade? I suspect it has something to do with the winds. 
 
 Any info will be highly appreciated.
 
 Thank you,
 
 Dan Uza
 
 
 
 
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial
 
 
>>> 
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>> 
> 
> ---
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> 
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[John Davis via sundial]

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Hi Dan,
This is a fairly typical diptych dial, probably 17th century. Museums such as 
the Whipple in Cambridge have large collections. It would probably be possible 
to date yours more accurately by careful comparisons.
The string gnomon for the horizontal dial is fixed to the wrong point - it 
should come from the intersection of the hour lines on the horizontal dial.
The two scaphe dials normally show Italian and Babylonian hours.
The windrose on the outer surface is for showing wind direction. The small hole 
in the panel allows the compass needle to be observed when the dial is closed. 
The counter-changed rule is not original, I believe, and is an inappropriate 
replacement. There should be a small vertical windvane which would fit in the 
centre of the rose.
I hope this helps.
Regards,
John--- Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: Dan-George Uza 
 To: Sundial List  
 Sent: Friday, 10 August 2018, 9:23
 Subject: Dyptich sundial - help!
   
Dear all,
I've recently found this piece in a museum near me and I need your help in 
dating it. 
Why are the hour marks offset? I suspect a correction for latitude. And what do 
the two small circular dials on the bottom measure?
Also what would be the purpose of the circular shape containing the alidade? I 
suspect it has something to do with the winds. 
Any info will be highly appreciated.
Thank you,
Dan Uza


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[no subject]

[John Davis via sundial]

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Hi Ian,
I have been searching for the Dickens sundial for a number of years and wrote 
briefly about it in the March 2013 BSS Newsletter. The trail has gone cold 
since then though one of my contacts in the Dickens Society did send me quite a 
good B&W photograph which allows the inscription to be read and the profile of 
the gnomon to be seen. It came from a book. If the dial does resurface, it 
should be easy to recognise.
Regards,
John
 Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: Ian Maddocks 
 To: "sundial@uni-koeln.de"  
 Sent: Saturday, 21 July 2018, 9:21
 Subject: Dickens' sundial
   
 Hello Diallists
Whilst trawling Instagram #sundial i found this, asking for info about a dial 
once belonging to Charles Dickens.  Can anyone help them?There's a drawing and 
photo provided in the link 
belowhttps://www.instagram.com/p/BldQFsbAixH/?tagged=sundial
Ian MaddocksChester, UK53°11'50"N  2°52'41"W



dickensmuseumThe Missing Sun-Dial
**
The sun-dial stood 4ft 8in high, in the garden at Gad’s Hill (Dickens's final 
home) in a most prominent position as it was considered one of Dickens's most 
valuable treasures.
*
After Dickens’s death [in 1870], it was bought by Mr. Crighton, of Rochester. 
Alice Morse Earle, in her 1902 book Sundials and Roses of Yesterday, says that 
the dial was later sold in London for the sum of £50. An article in the 
Pittsburg Press, 14 February 1899, gives more details “There is offered for 
sale by a curiosity dealer in London the old sun-dial and stone column formerly 
the property of Charles Dickens.’ In 1907 it was exhibited in the ‘Pickwick 
exhibition’ in London, and had been lent by the company Francis Barker sundial 
and barometer specialists, 12 Clerkenwell Road, London. The company was also 
making replicas of the original to sell.
*
As we continue our search, let us know if you can shed any light on the 
mysterious whereabouts of the sundial.
---
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[no subject]

[John Davis via sundial]

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Hi Steve,

Most Scottish lighthouses were equipped with sundials from the firm of A Adie 
from Edinburgh. However, these were all sold off some years ago - there was a 
picture in the BSS Bulletin of about 20 of them at the foot of a lighthouse 
just before the sale.

The dial in your picture is a different design with raised numerals etc and may 
be a one-off. I’m afraid I don’t know the maker.

Regards,

John
——

Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


> On 12 Jul 2018, at 20:56, Steve Lelievre  
> wrote:
> 
> 
> My recent visit to Shetland took in the recent summer solstice, allowing me 
> to experience for myself how Shetland's summertime sunsets are very late and 
> sunrises are corresponding early. Daylength at the solstice was around 19 
> hours, with (civil) twilight taking up another 3½ hours or so.
> Here is a photo I took of a sundial at the Eshaness Lighthouse (60.489314°N 
> 1.627209°W). Unfortunately it's on private property, so I couldn't get close 
> enough to read the the little plaque. The current lighthouse was completed in 
> 1929 so I guess the dial may be that early too.
> In Shetland the sun doesn't go anywhere near the zenith even at midsummer so 
> I was surprised by the height of the gnomon. It's just asking to be dinged, 
> but Shetlanders are good and gentle folk so there no sign of vandalism; just 
> a bit of rust and corrosion. 
> I wonder why the dial spans only 12 hours? I have seen a number of other 
> dials that only cover 12 hours but I've never really questioned that 
> attribute before. Of course in this case they've stuck the dial where the 
> nearly building obscures the sun late in the day, so evening hours don't 
> really matter. That aside, surely we should expect a dial made for such a 
> northerly location to reflect the extreme summer daylengths? There is plenty 
> of open space nearby where the dial could have been sited to accept sunlight 
> throughout the summer evenings.
> To me it seems a trivial matter to design a dial that covers the full 
> midsummer daylength. Can anyone justify, or at least explain, the 12 hour 
> limit?
> 
> Steve
> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
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[John Davis via sundial]

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text is therefore in an attachment.--- Begin Message ---
This is my second attempt to send this message, hopefully without having the 
subject stripped off and the message encapsulated this time
Hi all,
I wonder who designed it? They incorporated a gapped gnomon as seen on the 
Spot-On sundials of Piers Nicholson (Piers, you should have patented the idea!) 
but it looks as though they used the wrong delineation origins for the ‘back 
hours’.
Regards,
John Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: Kevin Karney 
 To: John & Deborah Goodman  
Cc: Sundial List 
 Sent: Saturday, 30 June 2018, 11:53
 Subject: Re: Missing an opportunity
   
JohnNot very beautiful, as you say,  by pretty impressive technology - I'll try 
to get to see it. Berkeley Castle is not too far from my home. I'll post some 
photos if I get there.Kevin



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[no subject]

[John Davis via sundial]

Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
eigentliche Nachricht steht dadurch in einem Anhang.

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text is therefore in an attachment.--- Begin Message ---
Hi all,

I wonder who designed it? They incorporated a gapped gnomon as seen on the 
Spot-On sundials of Piers Nicholson (Piers, you should have patented the idea!) 
but it looks as though they used the wrong delineation origins for the ‘back 
hours’.

Regards,

John
——
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


> On 30 Jun 2018, at 11:53, Kevin Karney  wrote:
> 
> John
> Not very beautiful, as you say,  by pretty impressive technology - I'll try 
> to get to see it. Berkeley Castle is not too far from my home. I'll post some 
> photos if I get there.
> Kevin
> 
> 
>> On 28 Jun 2018, at 16:03, John Goodman  wrote:
>> 
>> The sundial shown at this link looks completely conventional but it was made 
>> out of stainless steel using a 3D printer. Someone at the Renishaw company 
>> should have contacted this list to commission a more interesting design!
>> 
>> http://trends.directindustry.com/project-181814.html 
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> 
> 
> ---
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> 
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Re: Barrington Court multi-face dial

[John Davis]

Hi Keith,
The Barrington Court dial appeared on the back cover of the September 2013 BSS 
Bulletin (vol. 25(iii)). The accompanying caption read:
"The dodecahedron dial at Barrington Court (NT), Ilminster, Somerset. It 
featured in the March 2013 issue and is seen here from the south, though none 
of the dials faces exactly south. It is surprisingly small with the actual 
polyhedron at not much more than head height. Recorded early in the Society's 
history (SRN0040), it is in good condition and a nice example. Photo: John 
Davis."
The March 2013 article (by Peter Ransom) is really about an indoor dial and 
does not provide much more detail of the polyhedral dial, other than saying it 
has 5 reclining faces on the top row and 5 proclining ones in the bottom row. 
I'm not sure if the BSS Register has more info.
Regards,
John Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: "Keith E. Brandt, WD9GET" 
 To: sundial  
 Sent: Friday, 11 August 2017, 21:09
 Subject: Barrington Court multi-face dial
   
  Could someone point to/send me a description of the multi-face dial at 
Barrington Court in Somerset? I'm only finding pictures via standard web 
searches. 
 
 -- 
  ~~
  Keith E. Brandt, MD, MPH
 wd9...@amsat.org  
 
  Christianity and science are opposed… but only in the same sense as my thumb
 and forefinger are opposed- and between them I can grasp everything.
   —Sir William Bragg (Nobel Prize for Physics- 
1915)
 
  *This message transmitted with 100% recycled electrons   
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Re: new work on European pocket dials in Colonial America

[John Davis]

Hi Sara,
Congratulations to you and your co-authors. I would look forward to reading it 
but the link you give to Brill shows the book at the horrendous price of $150 
and my previous experience with other titles in this Brill series is that the 
printing quality can be very poor and the pictures very 'muddy'. Do you know if 
this one is any better, please, and if there will be better prices elsewhere?
Regards,
John-- Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: "Schechner, Sara" 
 To: "sundial@uni-koeln.de"  
 Sent: Saturday, 8 October 2016, 16:52
 Subject: new work on European pocket dials in Colonial America
   
 Dear All,  
  I am excited to report the recent publication of my essay—really a monograph 
inside a book—concerning sundials used in colonial North and South America:     
  EUROPEAN POCKET SUNDIALS FOR COLONIAL USE IN AMERICAN TERRITORIES by Sara J. 
Schechner, in How Scientific Instruments Have Changed 
Hands(http://www.brill.com/products/book/how-scientific-instruments-have-changed-hands),
 edited by Alison Morrison-Low, Sara J. Schechner, and Paolo Brenni, Scientific 
Instruments and Collections 5 (Leiden: Brill, 2016).   The essay is 55 pages 
and well-illustrated by photographs and maps.     The work discusses the kinds 
of portable sundials brought to the Americas by European explorers and 
settlers, and how these were adapted for use there.  It describes who needed or 
desired the sundials, where they were produced, and what their geographical 
range was.   The monograph analyzes archaeological evidence, household and 
business inventories, and most importantly, the very rare extant pocket 
sundials strongly linked to remote forts, tribal lands, battlefields, slave 
plantations, and colonial administrative seats.  These sundials shed light on 
the relationship of Time to imperialism and the transmission of cartographic 
and ethnographic knowledge during the colonial period.    I hope that you will 
enjoy reading it!      Sara    Sara J. Schechner Altazimuth Arts 42°36'N   71° 
22'W West Newton, MA 02465 http://www.altazimutharts.com/    Sara J. Schechner, 
Ph.D. David P. Wheatland Curator of the Collection of Historical Scientific 
Instruments Lecturer on the History of Science Department of the History of 
Science, Harvard University Science Center 251c, 1 Oxford Street, Cambridge, MA 
02138 Tel: 617-496-9542   |   Fax: 617-496-5932  
sche...@fas.harvard.edu|@SaraSchechner http://scholar.harvard.edu/saraschechner 
http://chsi.harvard.edu/       
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Re: Using linkages to draw curves on sundials

[John Davis]

Hi John,
I can offer:
J. Davis: ‘Alightweight laser trigon for layout of sundial lines’, BSS 
Bulletin, 11(iii), pp.144-146, (1999)
 which included drawing analemmic hour lines, and for an earlier purely 
mechanical example (built of Meccano!) there was
Noel Ta'Bois: 'Sundial Line Drawing Jig', BSS Bulletin 92.3 pp 28-30 (1992).
Regards,
John DDr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: John Pickard 
 To: Sundial List  
 Sent: Wednesday, 7 September 2016, 1:14
 Subject: Using linkages to draw curves on sundials
   
Good morning,

While researching mechanisms of wire strainers used to tighten wires in 
fences, and trying to find the theoretical mechanical advantages of the
different mechanisms, the first thing I learned was that "linkages" are the 
key to many of them. There's a whole branch of mechanics devoted to the
theory of these things which involve a zillion combinations of pivots and 
links to achieve various purposes, usually to transmit motion in a specific
manner.

The best explanation I found was Slocum, A. (2008). Fundamentals of design. 
Topic 4. Linkages
(http://web.mit.edu/2.75/fundamentals/FUNdaMENTALs%20Book%20pdf/FUNdaMENTALs%20Topic%204.PDF).
 
3.3 MB

But my curiosity lead me further, to a more mathematical treatment. 
Unfortunately and for unknown reasons, the Jefferson Lab Library has removed 
the title page.
Bizarre! I contacted the library and they gave me the full title etc.

Svoboda, A. (1948). Computing mechanisms and linkages. MIT Radiation 
Laboratory Series, Volume 27. New York, McGraw-Hill.
(https://www.jlab.org/ir/MITSeries/V27.PDF) (CAREFUL: 40.8 MB)

Among other things, this book shows how you can use mechanical linkages of 
various forms to draw the curves of mathematical functions. And seeing that
the curves on sundials are all defined by equations, I was wondering if 
anyone knows of any attempts to make a mechanical device of links and pivots
specifically for generating sundial equations, and thus drawing sundials? It 
seems to be a feasible but complicated way of doing it, with some serious
mathematics behind the linkages.

I don't include sundial rulers in this, as they are not physically linked 
and pivotted. Similarly, I don't include CNC machining as this involves 
moving the tool / work using a pre-programmed series of x, y and z 
coordinates. And of course, 3-D printing is out.

(And I still haven't figured out what sort of linkages are used in the wire 
strainers I'm studying!)

Cheers, John

John Pickard
john.pick...@bigpond.com 

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Re: Sixteenth-century wall dials with planetary hours?

[John Davis]

Hi Sara, Richard et al,
Sixteenth century wall dials of any sort are rare and have usually been 
repainted many times so it is not always clear how original the design is. 
There are a few 17th century dials with planetary hours around: you can see a 
couple in the articleM. Lowne & J. Davis: ‘Planetary Hours’, BSS Bull., 
25(iii), 40–48 (Sept 2013).
 which can be accessed here: 
http://www.flowton-dials.co.uk/wp-content/uploads/2013/07/Planetary-hours-ML-JD-Bull-25iii.pdf
Regards,
John--Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: "Schechner, Sara" 
 To: "sundial@uni-koeln.de"  
Cc: Richard L. Kremer 
 Sent: Thursday, 1 September 2016, 19:42
 Subject: Sixteenth-century wall dials with planetary hours?
   
 Dear All, 
Attached below is an inquiry from a colleague, Richard Kremer.  Please copy him 
on your replies.  Photos of the wall sundial in question can be found 
here:https://www.dropbox.com/sh/vdvlsur0w626kfe/AACEf1HseuQZm2SYtesQYHmra?dl=0  
  Best wishes,  Sara    Sara J. Schechner Altazimuth Arts 42°36'N   71° 22'W 
West Newton, MA 02465 http://www.altazimutharts.com/       From Rich Kremer:    
Sixteenth-century wall dials with planetary hours?    Around 1550, Zacharias 
Scultetus designed two wall dials for the facade of a handsome 
Renaissance-style house in Görlitz, Germany 
(see:https://www.dropbox.com/sh/vdvlsur0w626kfe/AACEf1HseuQZm2SYtesQYHmra?dl=0).
  The Solarium on the left includes lines for civil hours, Italian hours, 
Nuremberg hours. The Arachne on the right includes lines for the planetary 
hours (showing the ruling planets for each hour) and the solar altitudes, 
azimuths and astrological houses.    Are other sixteenth-century wall dials 
known that show planetary hours in this manner?    Please direct your 
correspondence torichard.kre...@dartmouth.edu.  Many thanks.       
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Re: A Strange Rainbow

[John Davis]

Hi Jackie,
I think that what you have there is a circumzenithal arc (CZA), possibly with a 
matching circumhorizontal arc (CHA). They are caused by the sun's rays 
refracting through ice platelets high in the atmosphere. You need the sun low 
in the sky for them to be seen. There are other ice haloes around the sun, 
particularly with 22 degree and 46 degree arcs, but the CZA and CHA are 
generally reckoned to be the most impressive and colourful, second only to the 
normal rainbow. You are very lucky to have seen it (I'm jealous) and 
congratulations for getting a photo.
Regards,
John-- Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: Jackie Jones 
 To: sundial@uni-koeln.de 
 Sent: Wednesday, 17 August 2016, 15:24
 Subject: A Strange Rainbow
   
Dear 
Sundial  folk,  I know this is not really sundial related, but I am sure 
someone will be able to explain this odd rainbow.  The picture was taken 
yesterday just before 6pm British Summer Time on a hot sunny day.  Looking west 
to the low sun, there was a rainbow above it with the ends of it curving 
upwards.   Below it there was a very faint second one in the same curve.  How 
does this happen on a dry day; normally the sun is in the opposite direction to 
the rainbow?  With best wishes in anticipation of an explanation,Jackie  Jackie 
Jones50° 50’ 09” N    0° 07’ 40” W  
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Re: Sundial in Risen movie

[John Davis]

Hi Dan,

Well spotted!  However, neither the horizontal sundial nor the hourglass was 
invented until the Middle Ages. Yet another example of Hollywood making up 
history!

John


Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


> On 6 May 2016, at 07:58, Dan-George Uza  wrote:
> 
> Hello,
> 
> I've spotted a horizontal sundial in the new biblical drama film Risen 
> (2016). You can see it in different scenes starting about half an hour into 
> the movie. It's alongside a hourglass on a desk belonging to Roman tribune 
> Clavius, the main character. I'm attaching a screenshot.
> 
> Dan Uza
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
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Re: Sundials with Greek alphabetical numerals

[John Davis]

EK stands for  Etos Kyriou, Greek for “the year of the Lord”. See J.Davis, MJ 
Harley & H James, 'Joseph McNally's Slate Sundials', BSS Bulletin 16(iii) 
pp.110-116.
John Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/


  From: Patrick Powers 
 To: Dan-George Uza ; Sundial mail list NEW 
 
 Sent: Friday, 15 April 2016, 11:01
 Subject: Re: Sundials with Greek alphabetical numerals
   
Hi That’s really interesting Dan.  I do not know of any dial in Britain/Ireland 
having Greek numerals for time indication.  However, I am aware of Greek being 
used on something like 20+ British dials but all but one of those only use 
Greek for their mottoes.  The one exception still does not use Greek time 
numerals but it does apparently have the dial’s date written in Greek; or at 
least it’s thought to be the date.  The dial was originally found in Paisley, 
which is the largest town in Renfrewshire, in Scotland but it now resides in 
England. What is there is:   It reads: E. K. XH HHH ∆∆∆ I Now, we have 
always supposed that the letters E. K. were the makers initials and the Greek 
capitals below represented the date.  However it’s not easy to know.  If we 
were dealing with ancient Greek coins (!) then their dates often started with 
an E (short for ΕΤΟΥΣ meaning ‘Of the Year’) but I don’t think that applies 
here!  The dial’s date is thought to be 1835 but I have not found a reference 
that translates what is on the dial into 1835.  Maybe this dial uses some sort 
of pseudo-Greek! Regards Patrick From: Dan-George Uza Sent: Friday, April 15, 
2016 8:50 AMTo: sundial@uni-koeln.de Subject: Sundials with Greek alphabetical 
numerals Hello! This is the only sundial with Greek alphabetical numbering I've 
come across in Romania and I was wondering: are they common in the rest of 
Europe? Dan Uza---
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Re: Sundial for the visually impaired

[John Davis]

Hi Dan et al,
Alan Mills was co-author of an article "Sundials for the Blind" in BSS Bulletin 
15(ii), 58-60 (June 2003).
Regards,
John- Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/

  From: "tonylindi...@talktalk.net" 
 To: sundial@uni-koeln.de 
 Sent: Thursday, 11 June 2015, 9:21
 Subject: Re: Sundial for the visually impaired
   

Hi Dan,
    Allan Mills exhibited a sundial for the blind at the BSS Yarnfield 
conference.  A sun spot heated a narrow copper strip wound around the outside 
of a cylinder with raised numerals in braille. A totlly blind person could then 
'feel' the time.

 I have a small jpeg if anyone would like to see it via < lindisun...@gmail.com 
>

Tony Moss

Original Message
From: cerculdest...@gmail.com
Date: 10/06/2015 8:35 
To: 
Subj: Sundial for the visually impaired



Hello, 
I was wondering: has anyone designed a sundial for the blind? Can there be one? 
How do you make people feel the shadow?
Dan Uza---
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Re: Rome Pantheon Sundial?

[John Davis]

Dear Claude et al,

We published an article by Robert Hannah on this topic in the BSS Bulletin:

R. Hannah: 'The Pantheon as a Timekeper', BSS Bull., 21(iv), pp. 2-4 (Dec 2009).

It is available in downloadable form on the BSS website at 

http://sundialsoc.org.uk/publications/the-bss-bulletin/

Regards,

John
--
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Claude Hartman 
To: Sundial List  
Sent: Monday, 5 January 2015, 21:13
Subject: Rome Pantheon Sundial?
 


Correct me if I'm wrong, but I don't recall reading about this on this list 
before.
An article from 2011, titled "Is Rome’s Pantheon a Giant Sundial?"
is shown at
http://www.history.com/news/is-romes-pantheon-a-giant-sundial

It quotes a book “Time in Antiquity,” by Hannahas saying
“In design terms, a conscious effort was made by the architect and builders to 
make the sun do something special in the Pantheon at the equinoxes,”

The book was reviewed in 2009 here: 
http://bmcr.brynmawr.edu/2009/2009-09-48.html





 
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BSS Bulletin - September

[John Davis]

Dear Dialling Colleagues,

The September issue of the BSS Bulletin was recently dispatched - members 
should expect to receive their copies soon (if not already!). As usual, the 
Contents List, together with one article for free download, is on our website 
at www.sundialsoc.org.uk.

Regards,

John
---
 
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Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php---
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Re: A few new Tables for the Gnomonist...

[John Davis]

Hi Kevin (et al),

Great stuff! I particularly like your item 4, the dates when the EoT has values 
of whole minutes. This is a useful feature for reproducing the scales on old 
dials. I have possible extension to this you might like to add: many of the 
larger and better-quality 'London' horizontals of the 18th century actually go 
down to half-minute intervals. In addition, they give the values of the 
maxima/minima as well.

Regards,

John D
---
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Kevin Karney 
To: Sundial  
Sent: Wednesday, 11 June 2014, 17:05
Subject: A few new Tables for the Gnomonist...
 


Dear Friends

I have been amusing myself with the astronomy of the Sun and have done a very 
complete coding of Meeus' routines for finding EoT, altitudes, azimuths, etc, 
etc. These deal with precession, nutation, aberration, parallax and the 
differences between TT, UT1 and UTC time.  This has yielded routines of much 
greater precision than are generally required by the gnomonist. However the 
speed of computers is such that lengthly routines are hardly noticed. So I have 
produced a javascipt routine and used it to prepare 4 tables for my website. 
They may be of interest to the dialist.

1) For a given civil time and location - all the usual solar parameters are 
calculated (nothing much new here - other than the precision)
2) A table giving the noon Equation of Time and Longitude Correction over any 
given year and location.
3) A list table of civil - v - solar time, altitude, azimuth, declination and 
local hour angle - for any starting date and time, covering any increment of 
seconds. (Useful if you are trying to set a dial and waiting for the Sun to 
shine)
4) An EoT table of the kind used on many old sundials, where the date is given 
every time the EoT changes by 1 minute. (Try changing the year from one to the 
next and see the change due to the leap aye cycle)

You can find these at
http://www.precisedirections.co.uk/Sundials/

Any comments, corrections, suggestions for additional tables or facilities 
would be welcome.
The input of latitude, longitude is a bit basic, but it is hoped to improve on 
this. Also, I plan to produce sunrise/solar noon/sunset tables.
If you use a browser that allows you to view a web-page's source (such as 
Chrome or Firefox), you can see the astronomical routine that is used.

Enjoy!

Best wishes
Kevin
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BSS Bulletin for June

[John Davis]

Dear Dialling colleagues,

The June issue of the BSS Bulletin, a special edition for our silver jubilee, 
was dispatched yesterday. Members should expect it in a day or so (rather more 
if long distances are involved!).

As usual, the Contents List and a sample article for download can be found at 
http://www.sundialsoc.org.uk/bulletin.php

Regards,

John
--
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php---
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Re: Request for information about a type of altitude dial

[John Davis]

Hi Steve et al,

It's usually just called a disc dial. I don't think the example shown is 
latitude-adjustable: the suspension point is fixed. All the historical ones 
I've seen are single latitude devices. Only the occulus is adjustable, for date 
(declination). Earlier examples had the hour points set on a concentric circle 
which meant that they were very inaccurate at some times of the year - the 
extension lobe on this one is an empirical attempt to improve things. The 
mathematics are dubious.

The earliest versions seem to be 16th century and there are quite a number from 
the 17th. I have one along similar lines found by a metal detectorist in 
Norfolk (UK).

Regards,

John

 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Steve Lelievre 
To: "sundial@uni-koeln.de"  
Sent: Sunday, 1 June 2014, 23:13
Subject: Request for information about a type of altitude dial
 

Hi folks,

http://www.pinterest.com/pin/301178293801331061/

What type of dial is this; I realize it's a form of altitude dial, but is there 
a specific name for it?

The accompanying note states that the dial can be adjusted for latitude by 
moving "the attachment point". I don't understand which part of the mechanism 
does that. Can anyone explain it for me?

Lastly, I'm appreciate references for articles or webpages that discuss these 
dials - history and mathematics.

Thanks,
Steve







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Minsmere sundial

[John Davis]

Fellow diallists,

TV viewers in the UK may be looking at the BBC2 series of 'Springwatch' 
programmes, with another 11 hours of nature-watching still to come. It is being 
filmed from the RSPB Minsmere (Suffolk) nature reserve. 

As the cameras wander around, look out for a visitor attraction on the reserve 
which appears like a series of wooden totem poles with carved oak bird 
sculptures on top and hand-cranked sound systems giving their calls. What the 
commentators may not tell you is that these posts constitute part of a simple 
sundial. A central post with a carved wooden ball on top acts the nodus and the 
other posts are positioned so that on designated dates/times, the ball's shadow 
will fall at the foot of the post.

As we've had 40mm of rain here today, the dial hasn't been in operation!

John
 ---
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Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php---
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Re: Moon dial.

[John Davis]

Hi David,

The starting point for making moondials must be Michael Lowne's classic article 
"Moondials and the moon" in BSS Bulletin 17(i) pp3-12.  In it, amongst other 
things, he shows that the value of 48 minutes for the daily offset is in fact 
not the best number to choose.

If you want something more exotic than just a sundial with a conversion table 
in the manner of the Queens' College dial, you could have one with 15 separate 
chapter rings, each one applicable for two days of the moon's age (symmetrical 
for waxing and waning). This is what the likes of Henry Wynne did on some of 
his very large horizontals. There is also a reasonably well-known one in slate, 
I think.  I've never seen it done on a vertical east dial - could be an 
interesting pattern.

The biggest problem with these schemes is knowing the age of the moon: unless 
the user looks it up in an almanac, online or with an app, you need to have 
little diagrams to match to the moon's appearance.

Regards,

John
-
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: David 
To: Sundial list  
Sent: Wednesday, 14 May 2014, 7:29
Subject: Moon dial.
 

Dear All,
I have had a request to construct a moon dial for a vertical east-facing wall.
This is new territory for me.
Can anyone point me in the direction of sources/computer programmes that would 
give me guidance?
David Brown
Somerton, Somerset, UK
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Re: Altitude dials as compasses

[John Davis]

Hi Jim et al,

Sutton's quadrant was described at some length in a two-part article:

M. Lowne & J.
Davis: ‘A Horizontal Quadrant of 1658 by Henry Sutton; Part 1’, BSS Bull., 
23(ii) 8-13 (Jun
2011).

 
with the second part in the following issue.

Regards,

John
---
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Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: James E. Morrison 
To: sundial@uni-koeln.de 
Sent: Tuesday, 13 May 2014, 2:40
Subject: Re: Altitude dials as compasses
 


This discussion has not included noting the capabilities of quadrants.  There 
are several stereographic quadrants that provide the solar azimuth for a date 
and solar altitude.   Among them are Gunter's quadrant (if azimuth curves are 
include), the Islamic quadrant based on a folded astrolabe and Sutton's 
quadrant which uses a southern projection.  Of the several, Sutton's quadrant 
is the easiest to use and the most precise for its size.

I am not aware of much in print about Sutton's quadrant other than the chapter 
in "The Astrolabe".  I can easily generate recreations if there is an 
interest/need.

Best regards,

Jim 
 James E. Morrison 
janus.astrol...@verizon.net 
Astrolabe web site at http://astrolabes.org
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Re: an 18th-century blue-and-gold sundial

[John Davis]

Hi Bob et al,

Thanks for that - good to know the house is up for sale and that the sundial is 
a selling feature. I believe that the dial is the one which can be seen from 
the street and was described by Harriet James and me in:
H. James & J. Davis:
‘A close look at a Salisbury dial’, BSS Bulletin, 17(iii),
pp.101-3, (September 2005).


Regards,

John
--
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Robert Terwilliger 
To: sundial@uni-koeln.de 
Sent: Wednesday, 30 April 2014, 12:49
Subject: an 18th-century blue-and-gold sundial 
 


 
An article in The New York Times April 29, 2014
 
Home
With a Royal Connection, in Search of a Buyer
 
A historic house in Salisbury , England where
King Charles II stayed is for sale on the public market for the first time in
600 years.
 
Excerpt:
Another terraced area has an 18th-century blue-and-gold
sundial on the exterior wall that features a quote from “Macbeth”:
“Life is but a walking shadow.”
 
Bob
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Re: Theatrical sundial

[John Davis]

Hi Jackie,

That sounds an interesting project.

To answer your question about what sort of sundial a hard-up doctor might have 
had in 1613, I think the most likely type would have been a pocket dial, either 
a small round wooden one like those found on the Mary Rose (there are modern 
replicas that could be used as a prop) or an ivory diptych one.

If he had a garden horizontal, the likelihood is that it would be a small, 
square horizontal one. Wall sundials weren't usually found on private houses at 
that time, except for the rich - see the reconstruction of the Stutton Hall one 
in the BSS Bulletin a couple of years ago.

If you stretch a point and do have a wall dial, it will be quite difficult to 
illuminate it so that the shadow is visible. The main illumination would need 
to come from a powerful spotlight which changed its position to simulate 
different times (or even dates). A practical solution would be to have a series 
of spotlights appropriately placed. The other requirement would be that any 
other light falling on the dial (as general background illumination) was 
minimised.

Good luck!

John

 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Jackie Jones 
To: Sundial Mailing List  
Sent: Wednesday, 2 April 2014, 17:12
Subject: Theatrical sundial
 


Dear All,
 
I am involved with a local theatre in the production of a play which takes 
place in 1613 in the herb garden of a doctor in Stratford on Avon.  I am 
suggesting to the producer and set designer that a sundial may be a good idea 
either on the house wall or on a pedestal in the garden.  But before I get too 
deep into ideas, could you please confirm that this is  correct and what sort 
of sundial would a country doctor who is not very wealthy have?
 
If a dial is on the house wall, I would like to suggest that, if the lighting 
can be arranged, for the shadow to move to show the passing of the day from one 
scene to another.  Does anyone know if this has been done on stage before?
 
The production is not until June, but we have just started the designs and 
rehearsals.
 
With best wishes,
Jackie
 
Jackie Jones
50° 50’ 09” N    0° 07’ 40” W
 
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Re: British Renaissance and sundials

[John Davis]

Hi Doug, Elizabeth et al,

Yes, the James Fox programme on the English Renaissance was interesting - 
though not absolutely correct with its facts. When describing Nicholas 
Kratzer's contribution to dialling, it was actually misleading and tended to 
perpetuate the myth that Kratzer introduced dialling to England (rather than 
just popularising it).

Kratzer wasn't "brought to Britain" by Henry VIII to look after his clocks. He 
came first to work for Sir Thomas More, quite possibly after an introduction by 
their common contact Erasmus. He then went to work for Cardinal Wolsey at 
Oxford and then to Henry. Our Nicholas was quick to smell the way that the 
political wind was blowing and work his way up the tree!

Kratzer was not an inventive dialler and his grasp of dialling (gained from 
copying out manuscripts - already 'old' - in a Bavarian monastery) was shaky. 
The late Peter Drinkwater (one of the few proper diallists to study Kratzer's 
notebooks in the Bodeian) was fairly dismissive of his abilities. 


Fox's demonstration of the operation of the Kratzer portable dial in the Oxford 
MHS using a torch was also misleading - it made it look as though the sloping 
edges of the gnomons were polar-oriented, which they aren't.

The next episode in the series will include a visit to Sir Thomas Tresham's 
famous Triangular Lodge, with all its crazy Catholic symbolism. Look out for 
the three sundials, the one on the north face with a gnomon repositioned 
upside-down. [English Heritage, who look after the building, were told many 
years ago but took no notice.]

So, enjoy the series by all means but remember the Royal Society's motto of 
Nullius in verba!

Regards,

John
---
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Douglas Bateman 
To: Sundial list  
Sent: Friday, 21 March 2014, 22:06
Subject: British Renaissance and sundials
 

I have just seen an excellent BBC programme called A Very British Renaissance. 
The presenter, Dr James Fox, included the painting by Holbein - The 
Ambassadors, and gave full credit to Nicholas Kratzner with the presenter 
handling Kratzner's personal polyhedral dial. He also conducted an interview 
with one of our top dial makers, Joanna Migdal, in her studio.

I gather not all will be able to see the BBC iPlayer, but worth a try. Perhaps 
some clever member could extract the relevant section of the programme.

Best wishes, Doug

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BSS Bulletin, March issue

[John Davis]

Dear colleagues,

The March issue of the BSS Bulletin was dispatched a few days ago and most 
members should have received their copies already. Let me know is yours doesn't 
arrive soon.

As usual, the full Contents list and a sample article are visible on our 
website at www.sundialsoc.org.uk

Regards,

John
--
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php---
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Re: SCOTTISH SUNDIAL

[John Davis]

Hi Dennis,

Bad news, I'm afraid! This is almost certainly an early-20th-century 
'decorative' dial of the type made by firms like Pearson Page Ltd and 
advertised in their catalogues. The spelling, the use of a motto at all, the 
arrangement of the hour numerals etc etc are all wrong for a 17th century 
English dial.

The good news is that, with a suitable gnomon, it would give quite a reasonable 
time-telling performance, at least in England if not in Scotland or (most of) 
America. And it is decorative!

Regards,

John
---
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Dennis Cowan 
To: sundial@uni-koeln.de 
Sent: Tuesday, 21 January 2014, 21:36
Subject: SCOTTISH SUNDIAL
 


 
I wonder if anyone on the list can help?  I 
received photos of this sundial from a lady in the USA.  She aquired it 
whilst she lived in Scotland some twenty odd years ago.  I'm trying to 
trace the possible origins for her.  I am not sure if the date of 1684 is 
genuine as it looks quite fresh, but a reproduction would surely use a 
known motto and I have never heard of this one "Ye Shade Teecheth".  The 
compass is also unusual to me.  Does anyone have any opinions?
 
Is it original or a reproduction.?  Does 
anyone recognise the motto or style of compass?
 
Many thanks
 
Dennis Cowan
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December BSS Bulletin

[John Davis]

Dear Sundialling Colleagues,

The December issue of the BSS Bulletin has just been posted out to members. If 
yours doesn't arrive in a reasonable time, please let me know.

As usual, the complete Contents List is available on our website 
(http://www.sundialsoc.org.uk/bulletin.php) together with a sample article for 
download.

Regards,

John
--
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

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Re: BOOK: Sundials: An Illustrated History of Portable Dials - H. Higton

[John Davis]

Hi Darek,

I think they are really the same book. If you look, they have the same ISBN. 
Hester did write another, more academic, book cataloguing the dials at the 
Greenwich NMM but that was a lot more expensive.

Regards,

John
-
 
Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/

BSS Editor http://www.sundialsoc.org.uk/bulletin.php



 From: Darek Oczki 
To: sundial@uni-koeln.de 
Sent: Wednesday, 18 September 2013, 14:10
Subject: BOOK: Sundials: An Illustrated History of Portable Dials - H. Higton
 

Dear Friends

I need your advise.

I found on eBay two listings offering 2 books with the very same title but 
having different covers. Here they are:

http://www.ebay.com/itm/Sundials-An-Illustrated-History-of-Portable-Dials-Hester-Higton-9780856675232-/390653600984
http://www.ebay.com/itm/Sundials-Hester-Higton-9780856675232-Book-/400552337200

Are these 2 different books or it's the same thing with 2 alternative covers?

I would be very grateful for any help.

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

GNOMONIKA.pl
Sundials in Poland
http://gnomonika.pl
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September BSS Bulletin

[John Davis]

Dear Dialling Colleagues,

The September issue of the BSS Bulletin was posted to members at the beginning 
of this month. I hope yours has arrived by now - let me know if not.  As usual, 
an updated Contents list and an article for free download are on our website at 
http://www.sundialsoc.org.uk/bulletin.php

Regards,

John
-
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Flowton Dials http://www.flowton-dials.co.uk/

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Re: Visibly Moving Gnomon Shadows

[JOHN DAVIS]

Hi Kevin (and Peter R et al),

I saw your SML post and will watch with interest what responses it gets.

One point, though: the value of 1.27 mm/sec as the lower limit of perception of 
movement is impossibly precise! I suggest that you would get +/-50% variation 
between different observers. Also, it will depend heavily on the situation: 
watching a laser spot on a piece of graph paper will give a value orders of 
magnitude different to following a distant aircraft on a clear blue sky.  What 
really matters is the rate of angular change and a stationary reference point.

Regards,

John
--
 
Dr J Davis
Flowton Dials



 From: Kevin Nute 
To: sundial@uni-koeln.de; Peter Ransom ; JOHN DAVIS 
 
Sent: Tuesday, 6 August 2013, 21:38
Subject: Visibly Moving Gnomon Shadows
 




The movement of the gnomon shadow at the famous Samrat Yantra equitorial 
sundial in Jaipur is reputed to be clearly visible to someone standing near the 
projection surface. I've read it moves as fast as 1 mm/s, though obviously not 
all the time.  At a given latitude, say 40º N, can anyone suggest a simple 
formula for estimating how far a projection surface would need to be from a 
vertical or horizontal gnomon for the shadow to move at 1.27 mm/s (the 
practical lower threshold of perceptible movement) I wonder?   Or in other 
words, what's the smallest sundial you could build to see real-time movement of 
the gnomon shadow with the naked eye?

 

Kevin Nute
Professor of Architecture
University of Oregon
School of Architecture and Allied Arts
Eugene, OR 97403
USA
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Isle of Wight sundials

[JOHN DAVIS]

Dear Dialling Colleagues,

Those of you interested in sundials on the Isle of Wight (just off the coast of 
southern England) might like to look at the website of Elizabeth Hutchings at 
www.hutchings1776.talktalk.net/sundials .

Elizabeth is an IoW resident and came to sundials quite late in life. Although 
not a member of the BSS, she has helped considerably in chasing out details of 
her local dials.

Regards,

John
-
 
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Re: Re azimuth lines

[JOHN DAVIS]

Hi Frank E,

As Frank K has said, your suggestion for reading azimuths with a polar-oriented 
gnomon and a set of declination lines (rather than with a nodus) is perfectly 
possible. But, in my experience, it would make the dial somewhere between very 
rare and unique as all the English examples I've ever seen make (or made) use 
of a nodus. Apart from anything else, trying to read shadows and dec lines on a 
wall sundial taxes the eyesight and visual coordination.

FK's wacky idea of a secondary, vertical, gnomon  to indicate azimuth directly 
is fun. There are cases on horizontal dials (eg the Whitehouse dial in Cumbria) 
where this was done. But again, I've never seen it on a vertical.

Any chance of the dial being conserved/restored?

Regards,

John
-
 
Dr J Davis
Flowton Dials



 From: Frank Evans 
To: "King, Frank" ; "Davis, John" 
; andrew.ja...@securetogether.co.uk; Sundial 
 
Sent: Friday, 2 August 2013, 20:36
Subject: Re azimuth lines
 

Greetings, fellow dialists,
Thanks to all for suggested solutions to my dial puzzle. As I read the dial 
picture, the azimuth lines related to the supposed nodus would have extended 
from the summer solstice curve, visible on the dial, up to a winter solstice 
curve now lost. If so this rules out the use of the figure 8 gnomon support as 
a nodus as its shadow in the picture falls outside this frame. Suggestions so 
far are that the gnomon is a replacement together with indications of how a new 
nodus might be calculated. I am still wondering about the alternative 
suggestion I made that there was no nodus but a vertical date scale at the 
sides. Then, selecting the date, you follow the declinational curve from there 
to the point where the gnomon shadow crosses the azimuth line and that gives 
the sun's bearing.

Is this correct in principle and do any dials anywhere use this method?
Frank 55N 1 W---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: azimuth lines

[JOHN DAVIS]

Hi Frank et al,

Dials with azimuth lines are rare but not unknown in the UK. Writing from 
memory, there is a rather nice one on Grundisburgh church near me and I believe 
the famous Queens' College, Cambridge, dial also has them amongst all the other 
furniture. There are a few others, I'm sure: didn't Ian Butson restore a wooden 
one?  

The key requirement, of course, is that there has to be a nodus so the gnomon 
on your lighthouse dial can't be original. The dial is in obvious need of 
restoration, or at least conservation. Perhaps a nodus could be added. Once the 
spacings of the azimuth lines have been measured, the trig to calculate the 
nodus position is straigntforwrad.

Regards,

John D

--

Dr J Davis
Flowton Dials



 From: Frank Evans 
To: Sundial  
Sent: Thursday, 1 August 2013, 14:03
Subject: azimuth lines
 

Greetings, fellow dialists,
Attached is a picture of the dial on a lighthouse in North Shields, England 
(55N 1.5W). It is probably from the eighteenth century and is badly eroded. As 
well as its hour marks it has a series of vertical azimuth lines labelled with 
the points of the compass. These may lie between the solstice curves. I am at a 
loss as to how the lines would have worked. There is no sign of a nodus on the 
gnomon (which looks old). Possibly, if there was a date scale associated with 
the azimuth lines, now eroded away, then it would be possible to get the sun's 
bearing from where the time line crosses the azimuth line but that looks pretty 
cumbersome. Any suggestions?
Frank 55N 1W


---
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Re: Unicode characters for degrees, minutes, seconds above the decimal point.

[JOHN DAVIS]

Hi,
 
If you are working in Word, type the two characters one after the other. Then 
select to the first, go to Font>CharacterSpacing>Condensed and choose an amount 
(eg 12pt) to match the character size.
 
There are other Unicode characters which effectively give a backspace(or zero 
character spacing) but MS's implementation of them in the various versions of 
Word are a bit doubtful.
 
Another solution would be to generate the required symbol as an extra character 
in the font, though this means it's difficult to pass the file to other people 
unless you convert it to a pdf with the modified font embedded.
 
Regards,
 
John
--

Dr J Davis
Flowton Dials
 


 From: J M 
To: sundial@uni-koeln.de 
Sent: Saturday, 6 July 2013, 1:37
Subject: Unicode characters for degrees, minutes, seconds above the decimal 
point.
  

My sundial software is also used for general astronomy calculations.
When I print or display an ephemeris I would like to use not just
the degree (°), prime (′) and double prime symbols (") but those symbols
above the decimal point (.) indicator.

In other words, instead of 127.42° display 127°.42 but have (°) aligned
directly above (.) as this is how it is typecast in old ephemerides.

Anyone know how to do this for not just ° but also ' and "?

I'm just looking for the (preferably unicode) characters not the
technique for converting the numerical value to the string representation.

-thanks

PS - I found this web-site to have lots of good astronomy related
unicode characters:

  Astronomical symbols
  http://en.wikipedia.org/wiki/Astronomical_symbols

PPS - I found this web-site

  
http://gis.stackexchange.com/questions/30754/field-calculate-degree-minute-second-in-different-format

      which displays a sample as 90°12'28.15" whereas I want 90°12'28".15
---
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Re: sundial for a blind person

[JOHN DAVIS]

Hi Brad,
 
There have been two articles on sundials for the blind in the BSS Bulletin:
 
Fer de Vries: 'A sundial for the blind', Bull 91.3, October 1991
 
A.A. Mills, P Stapleton & J Hennessy: 'Sundials for the blind' Bull 15(ii) June 
2003.
 
As a BSS member, I presume that you either have these copies or have bought the 
archive DVD!
 
Regards,
 
John
---

Dr J Davis
Flowton Dials

From: Brad Dillon 
To: "sundial@uni-koeln.de"  
Sent: Wednesday, 3 July 2013, 14:09
Subject: sundial for a blind person



Hello everybody,
has anyone ever made a sundial for a blind person?

Brad Dillon
www.armillaryspheres.co.uk 
http://www.charlestownsundials.com/
 

---
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BSS Bulletin

[JOHN DAVIS]

Dear Dialling Colleagues,
 
The June issue of the BSS Bulletin has recently been dispatched to members. 
Should yours not reach you in a sensible time, please let me know.
 
As always, the running Contents list is on our website at 
http://www.sundialsoc.org.uk/bulletin.php and there is a sample article for 
free download.
 
Regards,
 
John
- 
Dr J Davis
BSS Editor---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Man Wants heliochronometer

[JOHN DAVIS]

Hi Kevin at all,
 
If you want really high resolution from a small solar timekeeper, try a 
dipleidoscope! They can resolve down to a second or two.
 
Regards,
 
John


Dr J Davis
Flowton Dials

From: Kevin Karney kar...@me.com



These dials are latitude adjustable, correctable for longitude and summer time 
hours. They are meant for permanent installation so no do have levelling screws 
or compass. There is no my knowledge any heliochronometer that will tell the 
time better than 30 seconds accuracy, but I would love to be corrected on that!

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

Very early equal-hours quadrant discovered

[JOHN DAVIS]

Dear colleagues,
 
Archaeologists in Zutphen, The Netherlands, have uncovered a copper-alloy 
quadrant marked for equal hours. Stratification of the layers is apparently 
indicating a date in the range 1300-1325 which, if true, predates the Richard 
II quadrants in the British Museum by around a century. For a press release see:
 
http://www.zutphen.nl/Nieuws/Nieuwsberichten/April/Oudste_horloge_van_Noord_Europa_gevonden_in_Zutphen/Persmap_quadrans
 
There is an English version of the press release which currently contains 
factual errors which we are working to correct. Detailed studies of the 
underlying geometry used in this case are ongoing.
 
Regards,
 
John


Dr J Davis
Flowton Dials---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Two sundial resources on the Internet

[JOHN DAVIS]

Dear Wolfgang,
 
Thank you very much for these two links - most useful.  I am getting a problem 
with the second link, though: Google opens the journal for me but the pages on 
the Erfurt sundials 
are blank except for the message 
 
"Sie haben entweder eine Seite erreicht, die nicht angezeigt werden kann, oder 
die Anzeigebeschrankung fur dieses Buch erreicht"

which presumably means that the article is not available as I am in the UK 
rather than Germany. Is there any other way I could access the article, please? 
- preferably in a form that can be auto-translated!
 
Regards,
 
John
-
 
Dr J Davis
Flowton Dials

--- On Sat, 20/4/13, Wolfgang R. Dick  wrote:


From: Wolfgang R. Dick 
Subject: Two sundial resources on the Internet
To: "Sundial Mailing List" 
Date: Saturday, 20 April, 2013, 20:04


Daniel Roth's "sundial links" at
http://www.infraroth.de/index.html?nav_d.html,/cgi-bin/slinks.pl
contain a link to
"Almost 200 pictures of sundials & other astronomical clocks
(by Peter Lindner)" at
http://home.arcor.de/peter.lindner/sundials.htm .

I visited this site today by chance when searching for something else,
and I found that the site now contains "959 Sundials/Astronomical clocks
in 3681 pictures" as written in the header. Very worth a visit.

A more special source, but very comprehensive is the paper "Historische
Sonnenuhren in der Erfurter Altstadt" (Historical sundials in the
historic center of Erfurt, in German only) by Tim Erthel, published in
"Mitteilungen des Vereins fuer die Geschichte und Altertumskunde
von Erfurt" 72. Heft, Neue Folge, Heft 19, 2011, p. 41-71,
and available for complete preview at
http://books.google.de/books?id=k0YvN5iEqJMC&pg=PA41 .

Best regards,
Wolfgang Dick
---
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---
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Re: Today's Google Banner - More

[JOHN DAVIS]

Dear Frank,
 
The EoT might change sign on Euler's 306th birthday but I very much doubt 
(without checking!) that the changeover was the same on the date of his birth! 
 
Regards,
 
John
--

Dr J Davis
Flowton Dials

--- On Mon, 15/4/13, Frank King  wrote:


From: Frank King 
Subject: Today's Google Banner - More
To: "sundial@uni-koeln.de" 
Date: Monday, 15 April, 2013, 9:29


I should, of course, have added:

   Happy Birthday to Leonhard Euler

306 years old today and still going
strong!

It is a happy coincidence that he
should have been born on the day
that the Equation of Time changes
sign.

Frank King
Cambridge, UK

---
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---
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RE: Sundial At Tower Court, Wellesley College

[JOHN DAVIS]

Hi Sara,
 
Your idea of writing up the Wellesley College dial is a good one - I for one 
would like to know the full story and read your experiences.
 
The replica dial isn't a bad attempt (other than that awful gnomon!) and 
appears to have been hand engraved. But the details of the Equation of Time 
scale are missing and the half-hour fleur-de-lys don't have the shape I would 
expect for a Cole dial. Do you know if the original dial plate still exists?
 
Best regards,
 
John


Dr J Davis
Flowton Dials

--- On Sun, 31/3/13, Schechner, Sara  wrote:


From: Schechner, Sara 
Subject: RE: Sundial At Tower Court, Wellesley College
To: "Tony Moss" , "sundial@uni-koeln.de" 

Date: Sunday, 31 March, 2013, 19:54







The dial plate is a reproduction of the early 20th century, and the gnomon a 
messed up replacement!  
 
I have been thinking of writing this up with the Team for the NASS Compendium 
as a short article on how to approach a dial found in the field.   Would that 
be of interest to others?
 
Cheers,
Sara
 

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Tony Moss
Sent: Sunday, March 31, 2013 2:22 PM
To: sundial@uni-koeln.de
Subject: Sundial At Tower Court, Wellesley College
 
http://www.dickkoolish.com/rmk_page/pictures_112312.html > 

A very fine dial plate but oh what a sad, sad, gnomon.

Tony Moss.
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March BSS Bulletin

[JOHN DAVIS]

Dear Colleagues,
 
The March issue of the BSS Bulletin has recently been distributed to members. 
As always, if yours doesn't arrive in a sensible time, please let me know.
 
The Contents list, together with a sample article for free download, is on 
http://www.sundialsoc.org.uk/bulletin.php
 
Regards,
 
John


Dr J Davis
BSS Editor---
https://lists.uni-koeln.de/mailman/listinfo/sundial

BSS Bulletin - December

[JOHN DAVIS]

Dear Dialling Colleagues,
 
The December issue of the BSS Bulletin has recently been dispatched to members. 
If yours doesn't arrive in a sensible time, please let me know.
 
As usual, the contents are listed on our website, 
http://www.sundialsoc.org.uk/bulletin.php and there is also one article for 
free download.
 
Regards,
 
John
---

Dr J Davis
BSS Editor---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: St. Margareth

[JOHN DAVIS]

Hi Bill,
 
I believe the lines on the dials are described by the designer (Chris Daniel, 
the BSS President) as being 'platinum', and the blue colour as 'enamelled' - 
I'm not sure if these are forms of 'gilding' and 'vitreous enamel', 
respectively.
 
Regards,
 
John
--


Dr J Davis
Flowton Dials

--- On Wed, 1/8/12, Bill Gottesman  wrote:


From: Bill Gottesman 
Subject: Re: St. Margareth
To: "Reinhold Kriegler" 
Cc: "Sundial Mailingliste" 
Date: Wednesday, 1 August, 2012, 14:00


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

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

Re: A Nodebox Sundial (for Macintosh users - only)

[JOHN DAVIS]

Hi Kevin,
 
That looks very good - I'll certainly be interested to see it in bronze.
 
>From memory, there are two dials at Ham House - which is this an "almost exact 
>clone" of?

Regards,
 
John
-
Dr J Davis
Flowton Dials

--- On Sat, 14/7/12, Kevin Karney  wrote:


From: Kevin Karney 
Subject: A Nodebox Sundial (for Macintosh users - only)
To: "Sundial List" 
Date: Saturday, 14 July, 2012, 17:02



Hi
Both my children have been married in ceremonies held in my brother's garden. 
To celebrate these events and for his kindness, he gets a sundial... !


You can see the final design for this dial at ...
http://www.precisedirections.co.uk/Sundials
The dial is almost an exact clone of a 1820's dial at the National Trust's Ham 
House in London. I have added the Equation of Time flame and various text. The 
dial will be photo-etched on 5mm phosphor bronze.


To make the graphics, I have used an absolutely free package called NodeBox 
available only on the Macintosh. (A version for Linux & Windows is under 
development). Like DeltaCad, Nodebox works from a text description file using a 
language called Python - which is fairly straightforward to learn if you are 
familiar with programming. 


I have done quite a bit of general development work on my dial and attached to 
this e-mail is the Python description file - which I thought I would share with 
any of you who might be interested. All Apple Mac users have to do is to 
download version 1.9 (not the experimental version 2) of the software 
from http://nodebox.net/, install it, open my attached file, press Command R 
and you get a gnomonically perfect horizontal dial (or so I hope), which 
exports to a geometrically precise .pdf file, which can go direct to the 
photo-etchers. If you wish, you can change the dial's parameters and modify the 
code as you please to make things work for you - no copyright. The attached 
file is just text, so can be opened with any word processor. It's virus free, 
of course.


The code works in northern and southern hemispheres - not tested for the tropics
The gnomon design varies with your latitude, but goes wild at high latitudes
You can choose hour numerals that point either outwards or inwards
It plots my Equation of Time "Flame" correct for your location and Time Zone
You can use any Font on your computer for the Hour & Minute markers - (Roman or 
Arabic for the Hours)
All the dial furniture is transformed to point towards the foot of the style


The most complicated bit of the development was the routines to transform the 
Hour numerals so that the fonts were first 'circularized' (vertical lines 
pointing to dial centre, horizontal lines made radial), then slanted so that 
radial lines point to the appropriate side of the style's foot. This involved 
decomposing the fonts to their Bezier curves, linearising the curves and then 
transforming the multitude of linear segments. Modify those routines at your 
peril


Let me know of any problems or errors.
Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595












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Re: Moore Sundial stolen

[JOHN DAVIS]

Hi Josef et al,
 
Thanks for that link. The theft of the sundial made yesterdays TV news here in 
East Anglia - perhaps the first time a sundial has featured there (and for all 
the wrong reasons...).
 
It is worth pointing out that the dial which was stolen was a small-scale 
replica of the large dial which was at The Times and has recently been 
installed in Germany. It was only about 1 metre high, so you may guess what the 
full-size version might be worth.
 
Regards,
 
John
--

Dr J Davis
Flowton Dials

--- On Fri, 13/7/12, Josef Pastor  wrote:


From: Josef Pastor 
Subject: Moore Sundial stolen
To: "'Sonnenuhrliste Uni Köln'" 
Date: Friday, 13 July, 2012, 16:11


Dear Dialists,

Henry Moore´s "Sundial 1965" has been stolen from Perry Green,
Hertfordshire, on Tuesday evening or in the early hours of Wednesday
morning. The details have the News agency Reuters: 

http://www.reuters.com/article/2012/07/13/us-britain-statue-moore-idUSBRE86C
0HX20120713?feedType=RSS&feedName=lifestyleMolt 

Best regards 
Josef Pastor


---
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---
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Re: making a compass

[JOHN DAVIS]

Hi John B,
 
Your suggestion of using a piece from the mainspring of a clock for a compass 
needle is quite a good one - I have done this. It needs to be tempered by 
heating and then allowed to cool slowly first. However, the disadvantage is 
that the material tends to be rather thinner than is ideal (0.3 to 0.5 mm seems 
to be normal) and so there is less 'magnetic moment' when the needle is in 
place. This makes it more sensitive to the 'stiction' of the pivot.
 
Regards,
 
John D


Dr J Davis
Flowton Dials

--- On Sun, 8/7/12, Morgie Terwilliger  wrote:


From: Morgie Terwilliger 
Subject: Re: making a compass
To: john.davi...@btopenworld.com
Date: Sunday, 8 July, 2012, 0:40


John's ideas are all right on.  John mentioned a piece of hard steel.  I wonder 
if a piece of clockspring would have the right properties.  You can take a 
clockspring out of the drive drum of a junk windup clock, and at least the 
outer coils can be straightened out flat.  I've seen magnetizing coils.  They 
are air-core solenoids (helical coils) of heavy gauge wire and they are 
energized by capacitive discharge using capacitors such as are found in photo 
flashes (strobes)

Best,
John Bercovitz






---
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Re: making a compass

[JOHN DAVIS]

Hi Jackie et all,
 
An interesting question! I have made compasses for replica dials and found it 
more difficult than I expected. If you want a quick answer, it would be to buy 
a cheap compass and pull it apart so that you can re-case it and make an 
appropriate compass card but keep the same needle and pivot.
 
If you want to make your own from scatch, the first thing is to kind suitable 
steel for the needle. Too 'soft' and it won't retain the magnetism, too 'hard' 
(like most stainless steels) and it will be impossible to magnetize. I found a 
piece in my junk box so I don't know its spec.
 
To make the needle, drill the centre hole first and then cut the needle to 
shape around it - using a Dremel or, if you want to be authentic, a jewellers 
saw with a very fine blade.
 
The pivot has to be non-magnetic: brass being the obvious material. Really old 
portable dials have a pyramid-shaped pivot but I turned mine on a watchmakers' 
lathe. The actual suspension point needs to be significantly higher than the 
level of the needle. The conical hole is a tricky thing to drill Ideally, 
the pivot should be a jewel but I've yet to find a suitable source - anyone got 
any suggestions?
 
The pin can be a piece of pianowire ground and polished to a sharp point.
 
I use a solenoid to magnetize the needle. You will then need to balance it for 
the local angle of magnetic dip, so that it hangs level. Either carefully 
shorten the 'heavy' end or use a blob of wax or soft solder underneath the 
light end.

Good luck,
 
John
-
Dr J Davis
Flowton Dials

--- On Wed, 4/7/12, Jackie Jones  wrote:


From: Jackie Jones 
Subject: making a compass
To: sundial@uni-koeln.de
Date: Wednesday, 4 July, 2012, 13:35







Hi All,
I would like to make a small (probably about 1.5 - 3cm diameter) compass for a 
sundial.   I have not made one before; I’m sure many of you have, can anyone 
give me any tips and instructions please.
Many thanks,
Jackie
Jackie Jones
50° 50’ 09” N.    0° 07’ 40” W.
 
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June BSS Bulletin

[JOHN DAVIS]

Dear Dialling Colleagues,
 
The June issue of the BSS Bulletin was dispatched a couple of weeks ago so all 
members should have received their copy by now.
 
As usual, the complete contents list can be found on the BSS website, 
www.sundialsoc.org.uk together with one article available as a pdf for free 
download.
 
Regards,
 
John
-

Dr J Davis
BSS Editor---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: sundials and tower clocks

[JOHN DAVIS]

Hi Andrew et al,
 
There is a picture of about 9 of the dials from Scottish lighthouses lined up 
on a wall (just before their sale in 1997) in BSS Bulletin 11(i), p. 49, 
February 1999.
 
The story of the Bath Pump Room Tompion dial has been in the Bulletin too - all 
(sundial) life is there!
 
Regards,
 
John
--

Dr J Davis
Flowton Dials

--- On Wed, 16/5/12, Andrew James  wrote:


From: Andrew James 
Subject: RE: sundials and tower clocks
To: "Sundial List" 
Date: Wednesday, 16 May, 2012, 12:06









Dear John, Frank, Kevin, et al,
 
I remember a letter from Charles Aked in Antiquarian Horology circa 1970 
showing his son (then about 8?) at one of the Scottish lighthouse dials in situ.
 
I believe they were all (?) sold off perhaps about 15 years ago and think I 
have a cutting somewhere from a newspaper article showing them in a sort of 
well ordered heap. 
 
Regarding the Tompion dial at the Pump Room, a letter in Horological Journal in 
I think March 1960 shows what is probably this dial, so actually it was 
“discovered” by that writer near Bath some years before Brigadier Neilson 
“found” it and presented it to the Pump Room.
 
Regards
Andrew James 
 
This message has been scanned for viruses by MailControl.


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re: sundials and tower clocks

[JOHN DAVIS]

Dear Frank et al,
 
Thank you for the extract from the General Order for lighthouse dials. The 
thing which surprises me is that it is the EoT value engraved on the sundial 
that is being taken as the correction figure, rather than one for the date in 
question published in the current Nautical Almanac. Clearly, only average 
accuracy could be achieved in this way.
 
Regards,
 
John
---

Dr J Davis
Flowton Dials

--- On Wed, 16/5/12, Frank Evans  wrote:


From: Frank Evans 
Subject: re: sundials and tower clocks
To: "Sundial" 
Date: Wednesday, 16 May, 2012, 11:01


Greetings, fellow dialists,
I know of two particular instances where dials were used to regulate clocks. 
The first is the noon line of 1829 in the cloister of Durham Cathedral. 
Obviously its only purpose was to mark the time of noon for the purpose of 
correcting the Cathedral clocks. The second refers to lighthouses. In a book 
entitled "From Scotland's Edge" by Keith Allardyce and Evelyn M. Hood the 
following appears:

Since a General Order of 29 January 1852, it has been the practice to have 
clocks set at local time calculated from sundial readings. The order is 
precise: "The Lighthouse Timepiece is to be kept right, by observing, if 
possible, once a week, the indication of the Sun-dial, in the following 
manner:- The Principal Keeper shall go to the dial, when the sun is shining, 
and shall watch until the shadow of the style touches any hour, half hour or 
other time agreed before hand with the Assistant, who shall stand on the 
balcony, waiting a signal from the Principal. The Principal shall then make the 
signal, on seeing which, the Assistant shall immediately set the Timepiece to 
the time already agreed upon. The Principal shall then take a note from the 
Table of the Equation of Time engraved on the Sun-dial, of the number of 
minutes by which the clock should differ from the time given by the dial; and 
shall afterwards proceed at once to the Lightroom where he shall
 put the timepiece back or forward according as the Clock shall be slower or 
faster than the Sun at the time.


Sundials were universal at lighthouses throughout the UK although they have not 
all survived, of course.
Frank 55N 1W
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Re: Does anyone have contact details, for Brian Main ?

[JOHN DAVIS]

Dear Linda,
 
I have a telephone number but not an email for Brian Main (contact me off-list).
 
I believe that the dial was made to a design from Modern Sunclocks. The two 
rings of hour numbers are for GMT and BST (give or take the EoT correction). 
Otherwise, it is a standard analemmatic dial.
 
Regards,
 
John
-

Dr J Davis
BSS Editor

--- On Sun, 22/4/12, Linda Reid  wrote:


From: Linda Reid 
Subject: Does anyone have contact details, for Brian Main ?
To: sundial@uni-koeln.de
Date: Sunday, 22 April, 2012, 13:18



This might be a bit of a "long shot", but does anyone on this Mailing List
have contact details for Brian Main - and whom I understand was the person
responsible for this 'analemmatic' sundial layout, at Port Sunlight (UK) ?

I am a mosaic artist, and recently visited "Lady Lever Art Gallery" (which
is the building shown in the background, of this picture).  There does not
seem to be any plaque or similar details near to this sundial itself - but
when I asked at the Gallery, they said it was someone named Brian Main who
had been in charge of co-ordinating installation, of this 'Human Sundial'.

I even asked a few local people - but nobody seemed to know anything about
it, and they were not exactly sure how it works, or why there are two rows
of numbers.  If anyone has some more information, I will be very grateful.

Yours sincerely,

Linda Reid.



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March Bulletin

[JOHN DAVIS]

Dear Dialling Collegues,
 
The March issue of the BSS Bulletin has recently been distributed to members. 
Please let me know if yours does not arrive in a sensible period.
 
As usual, the Contents list, and a sample article for free download, is on the 
BSS website at http://www.sundialsoc.org.uk/bulletin.htm
 
Regards,
 
John


Dr J Davis
Flowton Dials---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Georg of Peuerbach

[JOHN DAVIS]

Dear Roger et al,
 
I don't think the later middle ages were quite as dark in Europe as you 
suggest. Science did make some progress (eg the 'Merton calculators') despite 
the disruptions of the various plagues.
 
For example, the monk Robert Stikford, working at St Alban's Abbey (not far 
from Oxford University) between 1367 and 1401, devised accurate methods of 
drawing vertical dials for equal hours. These included walls in declining 
directions. However, he used a nodus point rather than a polar-aligned gnomon: 
looking at his drawings, he was tantalizingly close. [For a preliminary 
description, see my article in the December 2011 BSS Bulletin.] He was 
calculating altitudes and azimuths to arc-minutes.
 
According to Ernst Zinner, the first person in Europe to write about polar 
gnomons (in an equinoctial dial) was Nicholas de Heybech (various spellings) in 
1431. I have so far been unable to trace the relevant MS. But it wasn't a new 
discovery, so we have a narrow range of time when it was either (re)invented in 
Europe or introduced from the Islamic world.
 
Re the two dials on Braunschweig Cathedral: the dating of these is extremely 
problemmatical and I don't believe Zinner's dates - even he changed his mind!
 
There is still much to learn of early dialling! Peuerbach did much good work 
but he wasn't the first.
 
John
--

Dr J Davis
Flowton Dials

--- On Wed, 15/2/12, Roger Bailey  wrote:


From: Roger Bailey 
Subject: Georg of Peuerbach
To: "Sundial List" 
Date: Wednesday, 15 February, 2012, 5:43




I have been looking at the renaissance, the coming of age of science in general 
and sundial science in particular in Europe. The dark ages were just that, 
winter, a survival regime for intellectual thought and physical existence. With 
the renaissance things changed, like blossoms in the spring or the coming of 
age of people.  I tend to view the world through a specific window, the prism 
of sundials. This gives a distorted but colorful view that avoids much of the 
noise in the general historical review and provides a unique perspective. 
Everything I need to know was learned through sundials
 
Here my specific interest is the introduction of the polar gnomon. This 
innovation gave us sundials that were independent of the seasons and could be 
viewed from a distance, public instruments rather than private tools for 
timekeepers and astronomers. On a planar sundial with a polar gnomon,  
the shadows did not race off on tangents. Hour lines were constrained and 
visible on a dial face.  In the Moslem world, by the 14th century, there was an 
a established science of astronomy, mathematics, instruments and sundials. In 
1371 Al-Shatir most likely created the first planar sundial with a polar 
gnomon, almost as an aside, when he designed the complex sundial at the Great 
Mosque in Damascus . He and his predecessors established the mathematics and 
science that lead to this development. What did we have at that time in Europe? 
Rudimentary fumbling in Germany, an couple of experimental dials in 
Braunschweig, a rough rule from the Monastery at Erfurt
 defining the angles for a sundial irrespective of latitude and wall 
declination, a table of rudimentary design information passed on by rote. In 
Europe when did real sundial science start? Perhaps with Georg Peuerbach 
(1423-1461) in Austria.  Google his name and follow the links. He is well known 
and respected by Austrians an intellectual force, the inventor of the ring and 
folding sundials, a skillful craftsman producing astrolabes and sundials and 
the designer of some of the first polar sundials in Europe. See 
http://www.regiomontanus.at/bild2_e.htm for the first folding sundial, a dial 
with a portable polar gnomon. or http://www.regiomontanus.at/bild2_e.htm the 
oldest sundial in Vienna.  Was he the spark of the Renaissance in sundial 
science? As one indication, Peuerbach taught Regiomontanus. Knowledge advanced. 
 
Can you comment on my naive point of view or add more background on the 
pioneering work of Georg Peuerbach?
 
Regards,
Roger Bailey
Walking Shadow Designs
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RE: Equinoctial vs. Equatorial

[JOHN DAVIS]

Dear Jim, Sara et al,
 
I agree with Sara that the terms 'equatorial dial' and 'equinoctial dial' are 
synonymous. I believe that the reason we have two terms is purely historical. 
English diallists writing in the 16th & 17th centuries were looking back at 
armillary spheres which represented the whole of the celestial sphere and had 
an equinoctial ring - which then became the receiving surface for the shadow in 
a number of dial types. The English, being a conservative race, have tended to 
stick with the term, though 'equatorial' is a better equivalent for the 
'horizontal', vertical' etc of other dial types.
 
The ingenious differentiation of the two names by Tony Moss is quite logical 
and has the possibility of becoming useful. But it is not currently widely 
known or adopted, to my knowledge.
 
Regards,
 
John
-

Dr J Davis
Flowton Dials

--- On Wed, 15/2/12, Schechner, Sara  wrote:


From: Schechner, Sara 
Subject: RE: Equinoctial vs. Equatorial
To: "Schechner, Sara" 
Cc: "Sundial Mailing List" 
Date: Wednesday, 15 February, 2012, 3:30







I classify sundials into three principal categories—those that find time from 
the sun’s hour angle; those that use the sun’s azimuth; and those that use the 
sun’s altitude—plus various combinations of two out of the three.   In the 
first category, we generally subdivide dials according to the plane on which 
the shadow is projected—i.e., horizontal, vertical, equatorial, polar,  etc.  
 
Sundials that project the sun’s hour angle onto a plane parallel to the equator 
are equatorial dials.  These include many forms such as the universal 
equatorial dial, the Augsburg-type dial, those with an armillary or crossed-Cs 
form, mechanical equatorial dials, and more.  The convention in the US is to 
call all of these  equatorial dials.  
 
In the United Kingdom, it is a convention to call them equinoctial dials.   
This is perhaps because the celestial equator is often called the equinoctial 
circle in the UK and the equinoctial circle/celestial equator are in the same 
plane as the terrestrial equator  
 
I prefer the label “equatorial” because it is a typology  constructed in 
parallel to the others (horizontal, vertical, polar) which refer to an 
orientation on the earth and don’t mix in celestial  designations.   
 
Cheers,
Sara
 
Sara J. Schechner, Ph.D. 
David P. Wheatland Curator of the Collection of Historical Scientific 
Instruments
Department of the History of Science, Harvard University
Science Center 251c, 1 Oxford Street, Cambridge, MA 02138
Tel: 617-496-9542   |   Fax: 617-496-5932   |   sche...@fas.harvard.edu
http://www.fas.harvard.edu/~hsdept/chsi.html
 
 
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Re: Sundial and the Leap Second

[JOHN DAVIS]

Dear Frank et al,
 
Not one of mine!  I think I recognise it as one of the Connoisseur Sundials 
range.
 
Good news (ish) that the leap second hasn't been abandoned (yet).
 
But the bad (UK) news yesterday was about the upcoming parliamentary vote 
proposing (yet again) that we adopt permanent BST. No further comment needed!
 
Regards,
 
John
-

Dr J Davis
Flowton Dials

--- On Fri, 20/1/12, Frank King  wrote:


From: Frank King 
Subject: Sundial and the Leap Second
To: sund...@rrz.uni-koeln.de
Date: Friday, 20 January, 2012, 11:38


Dear All,

Patrick Powers has drawn my attention to the
recent non-vote on the future of the Leap
Second. 

Those interested will probably already know
that the vote that was planned for this week
has now been delayed until 2015.

If you Google...

  Leap Second Future  or  Leap Second Vote

You will find more hits than you can cope
with.  The one with the best picture is:
  http://www.dailymail.co.uk/news/article-2088798/Leap-second-Conference-bigges
t-timekeeping-change-centuries.html?ito=feeds-newsxml

There is a nice view of a sundial resting
on a plinth but not bolted down.

Could this be a Tony Moss or John Davis dial?

The caption "...rendering sundials useless"
is a little over the top in my view!

The impression I get is that the Canadians,
the Chinese and the British are in favour
of keeping leap seconds but the French,
German and U.S. authorities want to get
rid of them.

Would any French, German or U.S. contributors
to this mailing list care to comment!!

Frank King
Cambridge U.K.


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Re: Headline: Second Oldest British Horological Instrument Found inAustralia

[JOHN DAVIS]

Hi JM,
 
Interesting indeed. It's a shame, though, that the statue shows Champlain 
holding the astrolabe from below, rather than suspended!
 
John D
-

Dr J Davis
Flowton Dials

--- On Mon, 5/12/11, J M  wrote:


From: J M 
Subject: Re: Headline: Second Oldest British Horological Instrument Found 
inAustralia
To: "John Pickard" 
Cc: "Sundial List" 
Date: Monday, 5 December, 2011, 0:05


Interesting what turns up in Canada!

  Astrolabe -- attributed to Champlain
  http://www.civilization.ca/cmc/exhibitions/tresors/treasure/222eng.shtml

  Champlain's astrolabe returns to Canada
  http://archives.cbc.ca/politics/language_culture/clips/17461/



On Sun, Dec 4, 2011 at 3:06 PM, John Pickard  wrote:



Hi Bob,
 
Interesting what turns up in Australia!

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September Bulletin

[JOHN DAVIS]

Dear Dialling Colleagues,
 
The September issue of the British Sundial Society Bulletin has just been 
dispatched to members. If you do not get yours within a sensible period, please 
let me know.
 
As usual, the Contents list is on the Bulletin page of the BSS website 
(www.sundialsoc.org.uk), together with a sample article for free download.
 
Regards,
 
John Davis
BSS Editor
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Dr J Davis
Flowton Dials---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Question on a possible sundial.

[JOHN DAVIS]

Hi Frans et al,
 
I think the device looks like a long-working-distance microscope, positioned to 
allow observation of the details of the flowers or the insects that land on 
them!
 
Regards,
 
John
-

Dr J Davis
Flowton Dials

--- On Fri, 19/8/11, Frans W. Maes  wrote:


From: Frans W. Maes 
Subject: Fwd: Re: Question on a possible sundial.
To: "Sundial List" , electr0magn...@msn.com
Date: Friday, 19 August, 2011, 20:19


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 
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" 
To: Duncan Meyers 
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
>           


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June BSS Bulletin

[JOHN DAVIS]

Dear Colleagues,
 
The June issue of the BSS Bulletin has now been dispatched to members - please 
let me know if yours doesn't arrive in a sensible time.
 
As always, the extended list of Contents for all issues and a free downloadable 
article from this latest issue are on the BSS website at www.sundialsoc.org.uk 
- just follow the links to Bulletin.
 
Regards,
 
John
--

Dr J Davis
Flowton Dials---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Two Prehistoric Portable Sundials?

[JOHN DAVIS]

Dear Mike et al,
 
I investigated these pictures some months ago, when they were first posted. I 
thought they might make a worthwhile, if speculative, article. The finder, 
though helpful, was unable to give any sensible information and, although not a 
sundial expert of any kind, had labelled them as such simply because they 
looked like that. He had no further research to show from experts in 
prehistoric flintwork or comparisons with any other finds.
 
I abandoned any idea of publishing these items.
 
Don't believe everything you see on the internet or on TV!
 
Regards,
 
John


Dr J Davis
Flowton Dials

--- On Thu, 14/4/11, Mike Cowham  wrote:


From: Mike Cowham 
Subject: Two Prehistoric Portable Sundials?
To: sund...@rrz.uni-koeln.de
Date: Thursday, 14 April, 2011, 8:49





Dear Sundial Friends,
I have just seen the pictures by the BBC of two 'Portable Sundials' from their 
'History of the World' series. I think that these are just two oddly shaped 
flints; not sundials. What do you think?
Happy dialling,
Mike Cowham
 
 
www.bbc.co.uk/ahistoryoftheworld/objects/DmrAs4M1SyWi4ET4e1-Zcw


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Re: Ben Franklin's Sundial Coin

[JOHN DAVIS]

Hi John C et al,
 
Here in England, 'Mind your business' (or 'Go about your business') is a not 
uncommon sundial motto - there is one on a vertical church dial from the 1700s 
not far from where I live. I wonder if Franklin saw one of them?
 
Regards,
 
John D
--

Dr J Davis
Flowton Dials

--- On Tue, 12/4/11, John Carmichael  wrote:


From: John Carmichael 
Subject: Ben Franklin's Sundial Coin
To: "'Sundial List'" 
Date: Tuesday, 12 April, 2011, 21:50








Several years ago at a NASS conference, Fred Sawyer gave us all a replica of 
America’s first coin from 1787.   I still have mine.  It was designed by 
Benjamin Franklin and featured a sundial on the front side with the text “Mind 
your Business”. Could he have been refering to sundial makers just a bit?
 
I was surprised while listening to the radio to hear the sundial coin 
mentioned.  
 
Here is the radio audio and video track- “Mind your Business”:
 
http://www.glennbeck.com/2011/04/11/mind-your-business/
 
Any sundial publicity is good!
 
 
 
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Re: The sundial goes to war

[JOHN DAVIS]

Dear Jim et al,
 
I think the item here is a draft of an article due to appear in the June issue 
of the BSS Bulletin. The author has 'jumped the gun'!
 
Regards,
 
John
BSS Editor
--

Dr J Davis
Flowton Dials

--- On Mon, 11/4/11, J. Tallman  wrote:


From: J. Tallman 
Subject: The sundial goes to war
To: "'Sundial List'" 
Date: Monday, 11 April, 2011, 17:30



Hello All,
 
Based on past discussions about sundial compasses being used in WWII, I thought 
some of you might enjoy this recent find which discusses the use of sundials 
for navigational purposes during wartime and includes pictures of several 
interesting devices:
 
http://sundials.co.za/THE%20SUNDIAL%20GOES%20TO%20WAR.doc
 
It is a document, so you'll have to tell your browser to open it.
 
 
Best,
 
Jim Tallman
www.artisanindustrials.com
jtall...@artisanindustrials.com
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BSS Bulletin contents

[JOHN DAVIS]

Dear Colleagues,
 
The online contents list of the BSS Bulletin has just been updated and now 
includes one more article for free download. Go to: 
http://www.sundialsoc.org.uk/bulletin.htm

Regards,
 
John
--
Dr J Davis
Flowton Dials---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: sundial on sale

[JOHN DAVIS]

Hi Fabio et al,
 
Thank you for posting this. It is a dial with an interesting provenance and 
will be described in a detailed article in the June issue of the BSS Bulletin. 
Book you copy now!
 
Regards,
 
John


Dr J Davis
Flowton Dials

--- On Thu, 17/3/11, Fabio Savian  wrote:


From: Fabio Savian 
Subject: sundial on sale
To: sundial@uni-koeln.de
Date: Thursday, 17 March, 2011, 10:44







Hi all
 
this mornig I found this google alert
http://www.artdaily.org/index.asp?int_sec=11&int_new=45765
 
ciao Fabio
 
Fabio Savian
fabio.sav...@nonvedolora.it
Paderno Dugnano, Milan, Italy
45° 34' 10'' N   9° 10' 9'' E
GMT +1 (DST +2)
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BSS Bulletin on DVD

[JOHN DAVIS]

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 +p&p. 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

Re: A 14th century sundial question from France.

[JOHN DAVIS]

Hi Bill (and other dialling colleagues),
 
The data that you show looks very similar to the Venerable Bede's shadow length 
tables (though the values are slightly different). This gives the length of a 
person's shadow on the assumption that their height is equal to six of their 
own feet (tall people generally have big feet!). But the hours are probably not 
the modern equal ones.
 
This topic will be discussed in some detail in the forthcoming June issue of 
the BSS Bulletin. A reason for the inaccuracies will be proposed, together with 
a rather more accurate version of the same table, to be found in an Anglo-Saxon 
manuscript.
 
Regards,
 
John
-

Dr J Davis
Flowton Dials

--- On Wed, 9/3/11, Bill Gottesman  wrote:


From: Bill Gottesman 
Subject: A 14th century sundial question from France.
To: "Sundial Mailing List" 
Date: Wednesday, 9 March, 2011, 1:06


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
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Re: Google's Art Project and dialling

[JOHN DAVIS]

Kratzer's 'strange' instrument in The Ambassadors is described in some detail 
in Peter Drinkwater's self-published 1993 booklet "The Sundials of Nicholas 
Kratzer". The item is shown disassembled and, as Drinkwater shows, is either 
faulty or inaccurately drawn.
 
Regards,
 
John
--

Dr J Davis
Flowton Dials

--- On Fri, 4/2/11, Kevin Karney  wrote:


From: Kevin Karney 
Subject: Re: Google's Art Project and dialling
To: patrick_pow...@compuserve.com
Cc: sund...@rrz.uni-koeln.de
Date: Friday, 4 February, 2011, 16:49


Now take a look at Holbein's Nicholas Kratzer, painted in 1528 which is in the 
Louvre (copy in National Portrait Gallery). Kratzer was a German mathematician, 
astronomer and instrument maker who worked as King Henry VIII's astrologer. He 
was a drinking friend of Holbein. Find his picture in the Wikepedia entry for 
Nicholas Kratzer.


Holbein was probably using Kratzer's instruments in the Ambassador's picture, 
which was painted a few years later in 1533. Same shepherd's dial, same strange 
instrument, same polyhedral dial (but unfinished), same little dial-like thing 
with the spike and square hole on his table.


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



On 4 Feb 2011, at 07:59, patrick_pow...@compuserve.com wrote:


After only recently learning of the Google Art Project, I looked at Holbein's 
Ambassadors today and like many others I was amazed at the resolution. This 
huge painting, it's not far off 7ft square, is here in London at the National 
Gallery and it is now available to view under Google's Art Project at: 



http://www.googleartproject.com/museums/nationalgallery/the-ambassadors


Painted in 1533 it has the most interesting collection of contemporary dialling 
equipment all of which are painted in immense detail.  There are two globes 
(one terrestrial and one celestial), a quadrant, a torquetum, a polyhedral dial 
and a shepherd's dial and some others I don't know, all of which are set in 
such a way as to tell some 'story' to the understanding viewer.


Until now it has been almost impossible for a sundial-interested visitor to the 
gallery to attempt to understand much of the detail - there just isn't time - 
but now with this view you can. You can even see for yourself the four place 
names marked on the terrestrial globe (one of which helped to identify one of 
the depicted persons as Jean de Dinteville, the Seigneur of Polisy) and you can 
even read the music and words in the open book and guess at the date and time 
shown on the shepherd's dial..


It doesn't (I think) help with viewing the anamorphic skull as a skull - or at 
least you still have to turn your monitor round to do so! - and I STILL don't 
understand the object behind the shepherd's dial...  Anybody know what that 
might be?


Patrick



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Re: BRASS ETCHING W/PHOTO RESIST

[JOHN DAVIS]

Hi John,
 
Glad to hear of someone in the USA doing photo-etching of dials. Do let us see 
your results in due course.
 
As a quick point, the dry film photoresist frothat Tony Moss mentioned is a 
three-layer (polythene-resit-mylar) structure. They don't actually make it 
themselves - I suspect it is imported from the USA. I use it regularly for 
small dials (12" or less). For larger dials, I use other materials. Whole 
reels, as you have found, are expensive but I have been able to buy some more 
cheaply when it is out of its use-by date. I might be outside its normal 
exposure range but, since I always do an exposure check first, that doesn't 
matter.
 
Regards,
 
John D
---

Dr J Davis
Flowton Dials

--- On Tue, 7/12/10, John Mulholland  wrote:


From: John Mulholland 
Subject: BRASS ETCHING W/PHOTO RESIST
To: sundial@uni-koeln.de
Date: Tuesday, 7 December, 2010, 15:31






I am presently experimenting with etching brass in ferric chloride. Tony Moss's 
info was my starting point. To date I have etched 2 plates. One good, one 
better. None dead on. 

Tony recommends a photoresist film called"ORDYL" manufactured by Mega 
Electronics in the UK. Their rep in the USA is Vital Presentation Concepts 
www.vpcinc.com. They want $300 for 2 rolls each 12"x100ft!
It has 2 layers.

I am getting my resist from www.capefearpress.com    It has 3 layers and is 
available by the sheet(s). More tedious to work with but much cheaper.

It would be great to hear from any members who are doing photo etching.

John Mulholland
jfmulhollan...@yahoo.com
Vermont


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Re: A giant non-dial for Milton Keynes??

[JOHN DAVIS]

Hi Tony et al,
 
The buried sundial is on the BBC website at 
http://www.bbc.co.uk/ahistoryoftheworld/objects/Aa1Ir_diS7iBuKens1XJWQ
 
I described it in an article in the BSS Bulletin, 16(ii), p.57 (June 2004).
 
The Manchester Road railway station dial has also been the subject of Bulletin 
articles, by John Wall and Roger Bowling. Full references to anyone 
interested...
 
Regards,
 
John Davis
---

Dr J Davis
Flowton Dials

--- On Fri, 15/10/10, Tony Moss  wrote:


From: Tony Moss 
Subject: A giant non-dial for Milton Keynes??
To: "Sundial Mailing List" 
Date: Friday, 15 October, 2010, 12:45


  Fellow Shadow Watchers,
                                        A BBC Radio 4 news item this 
morning mentioned an unusual sundial excavated from under a house floor 
and promised a picture on the R4 website.  I couldn't find the dial 
described but, in addition to a pic of a brass dial made for Manchester 
railway station, I followed a link to  "Giant Sundials Needs a Home"

Supposedly the 'Giant Sundial' was to be placed in Milton Keynes (52° 
North approx') but the elaborate patterns have never been cast and the 
concrete plinth remains bare.  This suggests it is supposed to be a 
horizontal dial?

Obviously a huge amount of inspiration and effort has gone into this 
production but did someone spot the very low gnomon angle(40° at a 
guess)  in time to prevent installation? Is a revolutionary kind of dial 
I've not met with or just another pretty non-dial?

http://news.bbc.co.uk/1/hi/england/7535649.stm

This may well be 'old news' to many but it is the first I have heard of it.

Tony Moss
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75th Bulletin again

[JOHN DAVIS]

Dear Colleagues,
 
Oops - I hit return too soon! The address should have been 
www.sundialsoc.org.uk.
 
Regards,
 
John
-

Dr J Davis
Flowton Dials---
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75th BSS Bulletin

[JOHN DAVIS]

Dear Dialling Colleagues,
 
I'm pleased to announce that the September issue of the BSS Bulletin, which has 
just been distributed to members, is our 75th edition. As usual, a list of the 
contents is available on our website www.sundialsoc.og.uk, as well as a sample 
article for free download. If you want to read the others, you need to join us/

Dr J Davis
Flowton Dials---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Denis Schneider

[JOHN DAVIS]

Dear Colleagues,
 
I am trying to make contact with the French diallist Denis Schneider and the 
email address I have been given doesn't work. Does anyone have an up-to-date 
address, please?
 
Regards,
 
John
---

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Flowton Dials---
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Jose Luis Basanta

[JOHN DAVIS]

Dear Dialling Colleagues,
 
Does anyone have an email address for Snr. don Jose Luis Basanta Campos, the 
Spanish diallist, please? I have a postal address but I'm hoping for a more 
convenient communication.
 
Regards,
 
John
---

Dr J Davis
Flowton Dials---
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Re: The first printed english gnomonical books on line!

[JOHN DAVIS]

Dear Nicola,
 
You're a hero!  What a wonderful treasure trove of material. Thank you very 
much indeed.
 
John
--

Dr J Davis
Flowton Dials

--- On Sat, 13/2/10, nicolasever...@libero.it  wrote:


From: nicolasever...@libero.it 
Subject: The first printed english gnomonical books on line!
To: "sundial" 
Date: Saturday, 13 February, 2010, 15:10



Dear Friends, 

the UPDATE n° 03 of digital links of the gnomonical digitized books, is ready 
on my web site

http://www.nicolaseverino.it 

At this time, you can download (for free) directly from my web site 46 first 
english printed gnomonical books!!
Several books are about the gnomonica; other, on mathematics, astronomy, 
navigations, ecc. have a chapter about sundials more or less great (someone 
have oltre 100 pages about sundials!).

This books are very rare and not easy to find in internet, because its are 
accessible only with a membership to the great institutions like EEBO, JSTOR, 
etc...
You can take this first opportunity to download this books for free from my web 
site. Enjoy!
Best wishes, Nicola Severino

This is the list of authors and titles of the books in this updates n° 3.

List
Anonimo, The astronomical Cylinder, or sun-dial. XVIII sec.

Blaeu Guilielmi, Institutio Astronomica, Oxoniae 1663. De Horologiis 
sciotericis;

Blagrave John, The Mathematical Jewel, 1585

Castelmaine Roger Palmer, The English Globe, London 1679

Collins John, The description and use of four several quadrants. “The use of 
Dialling scales”. London, 1750

Collins John, The sector on a quadrant, London, 1659

Dougharty John, Mathematical Digest. London, date (?)

Fenning D., The young man’s new universal companion. Of 
Dialling. London 1788

Ferguson James, A supplement to Mr. Ferguson’s book of Lectures. Dialling. 
London, 1767

Ferguson James, Lectures of selected subjects. London, 1776.

Fuller Samuel, Mathematical Miscellany in foru parts. Sundials. Dublin, 1770

Fuller Samuel, Practical astronomy in the description and use globes. Dialling. 
Dublin, 1732

George R. , A new universal history of arts and sciences…London 1759

Good John, Horometria, London 1730

Good John, Multum in parvo, London, 1706 

Good John, The art of Shadows, or Universal dialling, London, 1712 - also the 
edition 1731

Gordon George, Every young man’s companion. Dialling. London 1777.

Gordon George, Instroduction in Astronomy, 1726

Hammond Nathaniel, The elements of algebra. Of Dialling. London, 1753

Hawney William, The doctrine of plain and spherical trigonometry. Dialling 
arithmetical and instrumental, on all sorts of planes. London, 1750

Hopton Artur, Bacumul geodaeticum, sive viaticum. London 1610. Horomanci, or 
the Art of Dialling by the geodeticall staffe. 

I.W. Sciographia, or the Art of Shadows, London, 1635

Jones William, Methonds of finding a true meridian line useful in placing 
horizontal sundials, setting clocks and watches. London, 1795

La Hire Philippe, Gnomonicks, 1709, english edition.

Leadbetter Charles, Mechanik Dialling, London, 1737

Leadbetter Charles, The joung Mathematicians, London, 1793

Leybourn William, Mathematical Institutions. Sciographia or dialling. London, 
1704

Lyon John, Reflective dialling, London 1658

Mather W. The youg mans companion. Of Dialling. London, 1685

Morden Robert, An introduction to Astronomy Horologiographical problems. 
London, 1702

Morgan Silvanus, Horologiographia optica. Dialling universal and particular, 
London, 1657

Moxon Joseph, Mechanick Exercises. Mechanick Dialling. London 1703

Ozanam Jacques, Treatise of Gnomonicks, London, 1712

Ozanam Jacques, Recreations Mathematical. Problems of dialling. London, 1708

Potter John, A system of practical mathematics. Of Dialling. London 1757

Serle George, Dialling universal, London 1657

Smith Godfrey, The Laboratory. Gnomonicks, or the art of Dialling. London, 1756

Stirrup Thomas, Horometria, London 1652

Sturm Johann Christophorus, Mathesis Juvenilis, London, 1708

Taylor John, Thesaurarium Mathematicae. Of Dialling. London, 1707.

Turner John, Mathematical Exercises, London, 1750. The principles of dialling. 

Tuttel Thomas, The description and uses of a new contriv’d ecliptical double 
dial and also of the universal equinoctial dial. London 1698

Wells Edward, The Young Gentleman's, Dialling. London, 1712

W.P. The use of nocturnal. London 1655

Worgan John, The use of the universal Ring-dial, 1696

Wynne Henry, The description and uses of the general horological Ring Dial. 
London 1682






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Re: Copyright query

[JOHN DAVIS]

Hi Tony,
 
The same Egyptian dials appear in Hester Higton's Sundials - an illustrated 
history.. The credit she gives is to Aegyptisches Museum, Berlin, no. 19743 and 
19744.
 
Regards,
 
John D
--

Dr J Davis
Flowton Dials

--- On Sun, 15/11/09, Tony Moss  wrote:


From: Tony Moss 
Subject: Copyright query
To: "Sundial Mailing List" 
Date: Sunday, 15 November, 2009, 14:16


Fellow Shadow Watchers,
                                           For a commercial PowerPoint 
presentation currently in preparation I would like to include a picture 
of two Egyptian altitude dials (Tuthmosis III Egyptian) which appear on 
page 15 of  'Sundials History, Art, People, Science' by Mark 
Lennox-Boyd.   The acknowledgments therein state 'with permission of the 
British Library' but give no indication of the actual source.

As I have been unable to contact the author directly can anyone help 
with this to streamline a formal request to the BL?

Thanks in anticipation,

Tony Moss.


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RE: Analemma origins.

[JOHN DAVIS]

Hi John C,
 
That's a nice dial but it doesn't answer the question which I asked: the earliest x-y plot of EoT vs date to appear on a sundial (i.e. the familiar 4-peaked graph).
 
Re early analemmas (a different thing), Chris Daniel's monograph shows an earliest drawing for a horizontal meridian with analemma as by Deparcieux (1741) and for a vertical one in 1757. But Vogler's mean time equinoctial dial of 1719 in the NMM is earlier.
 
Regards,
 
John
---Dr J DavisFlowton Dials--- On Sun, 15/11/09, John Carmichael  wrote:
From: John Carmichael Subject: RE: Analemma origins.To: "'JOHN DAVIS'" Cc: "'sundial'" Date: Sunday, 15 November, 2009, 18:40




Hi John D:
 
You said:
<)? I haven't been able to find one prior to 1900 though I feel there must be one somewhere.
 
Take a look at this wonderful old etched glass dial made in 1788 at The Royal Castle in Warsaw Poland 
 
Stained Glass Sundial website at:  http://www.advanceassociates.com/Sundials/Stained_Glass/sundials_EGP.html
 
Look closely at the high definition original photos at the bottom and you will see the finely etched figure-of-eight analemma!  This is the oldest one I know of.
 






 

 


Dial 147
The King Poniatowski Dial


 




Maker: Made by Jean François Richer, an artist, French astronomer and Instrument maker for the king, Stanislas Augustus Poniatowski.Date: 1788Original Location: Lat: 52° 14' 50.425" N, Lon: 21° 0' 52.87" E. In The Royal Castle in Warsaw Poland. Behrendt's reverse engineering calculates its design latitude as 52.1° N. which corresponds with the location of Warsaw.Present Location: Lat: 52° 9' 53.124" N, Lon: 21° 5' 25.092" E. It’s mounted in a wooden box held by a window frame on the south side of The Wilanów Palace in Warsaw Poland. There is an outer pane of dirty glass in front of it. This is why it seems to be so
 unclean in the photos.Orientation: Its original and current location have a vertical inclination. Hans Behrendt's reverse engineering calculated its original declination was 14° east of south. Its present declination is south. So it would not function if its gnomon were reattached.Size: unknown exactly- about 2 m (79 in) tall.Adornment: The finely divided dial shows a sun calendar with the hours of VI o'clock am to V o'clock pm on the edges. Has 15 minute time divisions. For the first time on an historical glass sundial, the figure-of-eight analemma appears, indicating the deviation of true noon at the different seasons. Has the King's crown with the Polish and Lithuanian coat of arms, and in the centre is the coat of arms of the Poniatowski family. Further up, is the
 inscription: "Richer brevelé du roi en 1788". Patron was the Polish king.Mottos: the admonishing motto "Ultima Time" (Fear the Latest). The word "hour" is understood to be added.Condition: Good in 2009. Gnomon is still missing, however there is an picture of it. Darek Oczki trying to get it for us. At the end of the zodiacal hyperbola, the symbols are quite faint.Comments: All information here was provided by German dialist, Hans Behrendt and polish dialist, Dariusz Oczki. This is a valuable and historic sundial and is the second oldest etched glass sundial that we know of. Hans Behrendt said in his 1989 videotape: "Notice how the inscription is to be read inversely. Probably the pane was negligently inserted wrongly during a restoration." You can see this installation error in his old video photo ‘q’. The
 dial has since been reversed. Note that The Wilanów Palace also is home to the famous and most beautiful “Chronos Painted Wall Sundial” which you can see almost hidden behind the scaffolding in photos ‘o’ and ‘p’. You can see it more clearly and read about it at The Painted Wall Sundial Website at: Dial 31. Videotape Transcript of Dial 147 only: HereDariusz Oczki’s Email: HerePhoto Descriptions: Darek Oczki took photos ‘a’ to ‘p’ in 2009 and kindly sent them to us. He says: “It is very hard to take good photos because
 glass is very light there. There are some pics taken by a professional photographer, but I am not allowed to use them. He did something to make the sundial look dark with almost white markings. Unfortunately the palace is now being renovated so glass behind the sundial is covered with thousands of little and big stains of paint. As a computer graphic I have enhanced my pics a bit, so now one can see all the details even if they were taken during the day (It was very light outside so you would not see almost nothing on the sundial.” Other poor quality photos (‘q’, ‘r’, ‘s’) were copied from the videotape movie by Hans Behrendt called "Historische Glassonnenuhren" 1989. He said: "In 1966, Dr. Somerville of Mendota England photographed dial at the Wilanów castle in Warsaw. In 1984, a Mrs. Zusanna Prószynsk

Re: Analemma origins.

[JOHN DAVIS]

Dear Frank et al,
 
I'm tempted to digress further.. When was the first graphical - Cartesian - 
representation of the EoT on a real sundial (date as the x-axis and EoT on the 
y-axis)? I haven't been able to find one prior to 1900 though I feel there must 
be one somewhere.
 
Re questions on the representation of the figure-8 analemma: no one has yet 
mentioned Chris Daniel's BSS monograph on the subject, sadly out of print at 
the moment...
 
Regards,
 
John
---

Dr J Davis
Flowton Dials

--- On Sun, 15/11/09, Frank King  wrote:


From: Frank King 
Subject: Re: Analemma origins.
To: "Fred Sawyer" 
Cc: "Sundial List" 
Date: Sunday, 15 November, 2009, 16:59


Dear Fred,

You tempt me to digress...

> Once we have the idea of graphing tabular values...

It seems that the idea of graphs and graphing is not
nearly as ancient as one might expect.

I commend a book:

   Cosmic Imagery: Key Images in the History of Science
   - John D. Barrow, W.W. Norton & Company, Inc.

This has fascinating things to say about the earliest
graphs and you can see a transcript of a lecture given
by John Barrow at:

   http://www.gresham.ac.uk/event.asp?PageId=108&EventId=748

In this he says:

   ...something that most people are surprised to learn is
   a rather late arrival on the human intellectual scene:
   the graph, the good old graph.  Everybody thinks the
   Greeks must have been drawing graphs, and Isaac Newton
   must have been drawing graphs.  Neither of them ever did!

   ...the first graph that I... was able to find... was drawn
   in the tenth century by an unknown monk in France.  He was
   giving some lectures ... and he wanted to illustrate ...
   where the planets were...

   You have to wait until the mid-1300s before you find Erasme
   using graphs that he called latitudes in a slightly different
   way.  They look like graphs, but they have no scales, they
   usually have no axes, and he uses them as a sort of shorthand.

Of course it depends what you mean by 'graph'.  The 'first graph'
that John Barrow refers to has clear horizontal and vertical grid
lines and looks recognisably like a present-day graph, albeit
with the grid drawn freehand!

He gave the same lecture in Cambridge last March and since I
gave the immediately-following lecture (about the analemma!!)
I challenged him by asserting that I would count as a graph
any kind of two-dimensional plot...

I mentioned that there are plenty of pre-Christian-era sundials
which, in essence, allow the graph-like plotting of the path
followed by the tip of a gnomon during the course of a day.

He didn't accept that such dials are true graphs and I can
understand that.

Nevertheless I shall persist in thinking of dials as being
very closely related to graphs even if they are not quite the
same thing!!

Frank

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Re: Dials and clocks

[JOHN DAVIS]

Dear Brian and List members,
 
There was a picture of the Bath Tompion horizontal dial on the front cover of 
BSS Bulletin 19(iv), December 2007, with a thumbnail of the Equation of Time 
clock on the inside cover, with the caption.  In the following issue, a 
Readers' Letter from Sir George White explained that the dial may, or may not, 
have been the one which Tompion originally gave to accompany the clock. The 
dial had in fact been 'found' locally and was donated in the late 1960s - a new 
pedestal for it was made to stand on the outside windowsill, overlooking the 
Roman Baths. It is certainly an appropriate dial but its provenance is 
uncertain.
 
Whatever the case, it is good to have a Tompion clock and dial so close 
together.
 
Regards,
 
John Davis
--

Dr J Davis
Flowton Dials

--- On Mon, 19/10/09, Brian Albinson  wrote:


From: Brian Albinson 
Subject: Dials and clocks
To: "'Sundial List'" 
Date: Monday, 19 October, 2009, 3:39 PM





Gnomonists
 
>From last Saturday's Canadian Globe and Mail:
 
"In the Pump Room in Bath, England, there is a pendulum clock that was donated 
in 1707 by Thomas Tompion, a famous clockmaker.  On the windowsill close by is 
the sundial that was supplied with the clock"
 
Does anyone have photos of the clock and dial?
 
Brian Albinson

 
 
 
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September Bulletin

[JOHN DAVIS]

Dear Colleagues,
 
The September issue of the BSS Bulletin has recently been mailed out - please 
let me know if yours doesn't arrive (assuming you're a member, of course!).
 
As usual, the contents are listed on the Bulletin page at www.sundialsoc.org.uk 
and there is one article available for free download.
 
Regards,
 
John
---

Dr J Davis
Flowton Dials---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Augusta dial

[JOHN DAVIS]

Dear All, (especially in America),
 
Anyone know anything about this dial?:
 
http://kennebecjournal.mainetoday.com/news/local/6765882.html
 
Regards,
 
John
-

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Re: Dutch sundial

[JOHN DAVIS]

Dear Willy and other responders,
 
What a superb dial - colourful, clear and informative. Thank you for the 
pictures. My particular interest was in the rather unusual Latin motto, 
appearing in 1731, some time after Thomas Tuttell had used a simplified version 
of
 
"Preteritum Nihil, Præsens Instabile, Futurum Incertum" (The past is gone, the 
present transient, the future uncertain) 
 
The two Tuttell double horizontals with it must date to 1700 +/- 5 years and it 
is also on one of his portable analemmatic dials. Where does it come from? And 
how come a version appears on a Dutch dial a few years later (after Tuttell's 
death)? Can our classically-educated members throw any clues on the puzzle?
 
Regards,
 
John

PS Thank you to the kind people who mentioned the Sawyer Dialing Prize - I am 
very proud to be a member of the clan of winners.


Dr J Davis
Flowton Dials

--- On Tue, 25/8/09, Willy Leenders  wrote:


From: Willy Leenders 
Subject: Re: Dutch sundial
To: "JOHN DAVIS" 
Cc: sund...@rrz.uni-koeln.de
Date: Tuesday, 25 August, 2009, 8:19 PM


I made a page concerning this sundial on my website.
In Dutch language, but the pictures are rather clear.


And http://www.wijzerweb.be/groningen.html can help.



http://www.wijzerweb.be/groningen.html



Willy LEENDERS
Hasselt in Flanders (Belgium)


www.wijzerweb.be




Op 25-aug-2009, om 20:03 heeft JOHN DAVIS het volgende geschreven:






Dear colleagues (especially in the Netherlands)
 
Can anyone tell me anything about the sundial referred to in this extract from 
a tourist website:
 
 Follow the canal to the right until just after Kattenhage, where you can 
escape the city’s post-war urbanity in the Prinsenhoftuin (Princes’ Court 
Gardens), originally designed in 1625 with a rose garden and covered paths. 
When in bloom, the fragrant roses make it impossible not to linger, especially 
when the Theeschenkerij Tea Hut inside the garden tempts you to order a cup of 
tea (€0.80) and lounge in the sun or under one of the canopied underpasses. 
(Tea hut open M-F 10am-6pm, Sa-Su noon-6pm.) On your way out, ponder the advice 
of the Latin inscription on the sundial above the entrance: Tempus praeteritum 
nihil. Futurum incertum. Praesens instabile. Cave ne perdas hoc tuum (“The past 
is nothing, the future uncertain, the present unstable; ensure that you do not 
lose this time, which is yours alone”). 
 
The Latin motto also appears (slightly shortened) on two English double 
horizontal dials by Thomas Tuttell.
 
Thanks in anticipation!
 
John
--

Dr J Davis
Flowton Dials
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Dutch sundial

[JOHN DAVIS]

Dear colleagues (especially in the Netherlands)
 
Can anyone tell me anything about the sundial referred to in this extract from 
a tourist website:
 
 Follow the canal to the right until just after Kattenhage, where you can 
escape the city’s post-war urbanity in the Prinsenhoftuin (Princes’ Court 
Gardens), originally designed in 1625 with a rose garden and covered paths. 
When in bloom, the fragrant roses make it impossible not to linger, especially 
when the Theeschenkerij Tea Hut inside the garden tempts you to order a cup of 
tea (€0.80) and lounge in the sun or under one of the canopied underpasses. 
(Tea hut open M-F 10am-6pm, Sa-Su noon-6pm.) On your way out, ponder the advice 
of the Latin inscription on the sundial above the entrance: Tempus praeteritum 
nihil. Futurum incertum. Praesens instabile. Cave ne perdas hoc tuum (“The past 
is nothing, the future uncertain, the present unstable; ensure that you do not 
lose this time, which is yours alone”). 
 
The Latin motto also appears (slightly shortened) on two English double 
horizontal dials by Thomas Tuttell.
 
Thanks in anticipation!
 
John
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Dr J Davis
Flowton Dials---
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Re: Isaack Symmes 17th Century Sundial

[JOHN DAVIS]

Dear BarnardMD,
 
Isaack Symmes is a reasonably well-known maker. Another of his dials is 
described in:
 
M. Lowne & J. Davis: ‘Lines of Declination and Two Seventeenth Century Dials’,  
BSS Bull, 19(iii), pp.128-134, (June 2007).

I'm not a valuer though I do have one or two old dials that I have collected 
over the years and I would be very interested to see a picture of yours 
off-list, particularly showing the gnomon.
 
Regards,
 
John Davis

Dr J Davis
Flowton Dials

--- On Mon, 8/6/09, barnar...@aol.com  wrote:


From: barnar...@aol.com 
Subject: Isaack Symmes 17th Century Sundial
To: sundial@uni-koeln.de
Date: Monday, 8 June, 2009, 12:13 AM


I am looking for inputs as to the value of a brass, horizontal sundial, 4 
7/8"x4 7/8", 50-degree gnomon and marked "Isaac Symmes" but with no date or 
location. It is identical to the one made in the early 17th century shown at 
http://brianloomes.com/collecting/sundial/sundial.html#sundial except the 
gnomon is more ornate.



An Excellent Credit Score is 750. See Yours in Just 2 Easy Steps!
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BSS Bulletin - June 2009

[JOHN DAVIS]

Dear Colleagues,
 
The June issue of the BSS Bulletin has recently been dispatched to members - if 
your does not arrive in a sensible time, please let me know.
 
As usual, the Contents list is on the BSS website (www.sundialsoc.org.uk and 
follow the links to The Bulletin) and one sample article is available for free 
download.
 
Regards,
 
John


Dr J Davis
Flowton Dials---
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Re: The Eternal Sundial

[JOHN DAVIS]

Hi John et al,
 
I think the 'spiral dial' is probably a clever bit of photoshopping of the 
normal vertical dial in the same photostream!
 
Regards,
 
John D


Dr J Davis
Flowton Dials

--- On Mon, 11/5/09, John Carmichael  wrote:

From: John Carmichael 
Subject: The Eternal Sundial
To: "'Sundial Mailing List'" 
Date: Monday, 11 May, 2009, 3:22 PM








Hello Dialists, especially the Spaniards:
 
I came across this intriguing photo of an odd spiral-shaped multiple vertical 
dial that the photographer calls “The Eternal Sundial”.  He gives no 
information about it, but I think it might be located in Spain-possibly at the 
Susqueda dam because it is in the photographer’s photostream next to photos of 
the dam.  
See: http://www.flickr.com/photos/davidmontse/3166570780/in/photostream/ 
 
Also in this photostream is this photo of a more traditional vertical declining 
dial with the same decorative border design:
See: http://www.flickr.com/photos/davidmontse/3166570782/in/photostream/ 
 
So I bet both dials are on the same building. 
 
Notice the curved hour lines of the multiple dial.  I am not familiar with this 
kind of dial.  What kind of time do the multiple dials show?  And why do the 
multiple rod gnomons face in different directions?  
 
It is a beautiful design though and is most fascinating!
 
John
 
 
 
 
John L. Carmichael
Sundial Sculptures
925 E. Foothills Dr.
Tucson AZ 85718-4716
USA
Tel: 520-6961709
Email: jlcarmich...@comcast.net 
 
Websites:
(business) Sundial Sculptures: http://www.sundialsculptures.com 
(educational) Chinook Trail Sundial: 
http://advanceassociates.com/Sundials/COSprings/
(educational) Earth & Sky Equatorial Sundial: 
http://advanceassociates.com/Sundials/Earth-Sky_Dial/  
(educational) My Painted Wall Sundial: 
http://www.advanceassociates.com/WallDial 
(educational) Painted Wall Sundials: 
http://advanceassociates.com/WallDial/PWS_Home.html 
(educational) Stained Glass Sundials: http://www.stainedglasssundials.com 
(educational) Sundial Cupolas, Towers & Chimneys: 
http://StainedGlassSundials.com/CupolaSundial/index.html 
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Re: New equatorial dial

[JOHN DAVIS]

Dear Mike and Dialling Colleagues,
 
I'm pleased to be able to inform you that the article in Model Engineer which 
Mike refers to will also be published in the June issue of the BSS Bulletin. 
This version will contain both parts of the ME article, the second part 
describing the design of the EoT cam.
 
Regards,
 
John Davis
BSS Editor
-


Dr J Davis
Flowton Dials

--- On Wed, 18/3/09, Mike Isaacs  wrote:

From: Mike Isaacs 
Subject: New equatorial dial
To: "sundial" 
Date: Wednesday, 18 March, 2009, 10:11 AM

Dear All,

The current issue of the Model Engineer Magazine, Vol 202, No 4347, 13 - 
26 March 2009, has the first part of an article on the construction of 
an equatorial sundial with EOT correction.

The correcting element is an EOT cam similar to that used in the 
Pilkington and Gibbs heliochronometer.


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Experimental Method for Earth Radius

[JOHN DAVIS]

Dear Dialling Colleagues,
 
I'm forwarding this message from another mailing list as I believe it may be of 
interest to all sun-watchers. Mathematicians amongst you might like to work out 
the details of the 'fudge factor'.
 
Regards,
 
John
---

Dr J Davis
Flowton Dials

--- On Sun, 1/3/09, Brian Whatcott  wrote:

From: Brian Whatcott 
Subject: [rete] Experimental Method for Earth Radius
To: sexta...@yahoogroups.com, r...@maillist.ox.ac.uk
Date: Sunday, 1 March, 2009, 4:38 AM

I am relaying this note from a physics teachers list, believing it may be of
interest to you.   For me, it carried the same kind of frisson as reading about
Harrison's stellar transit method  for timing chronometers.

Brian W

David Bowman wrote:
> I've come up with a fairly simple means of measuring/calculating
> the size of the earth using only local measurements (not requiring
> multiple sightings at far away locations like Eratothenes' method
> needs).
>  The idea is to observe and time the motion of the terminator at
> sunset/sunrise ascending or descending the face of a building,
> pole, or other tall structure with an exposed vertical face.  It
> is a fairly simple exercize in trigonometry to realize that if one
> is situated on the equator during an equinox that the terminator
> ascends vertically at sunset and descends vertically at sunrise
> with a constant acceleration that is related to the rotation rate
> of the earth and the radius of the earth.  In this situation it is
> a high school-level calculation to see that if a is the vertical
> acceleration of the terminator then the radius R of the earth is
>  R = a*(T/(2*[pi]))^2
>  where T is the duration of one solar day.
>  If the observing location is not on the equator then there is a
> correction for the local latitude of the observer.  And if the
> time of observation is not during an equinox then there is another
> correction involving the declination of the sun due to the
> tilted path of the sunrise/sunset at the horizon.  Figuring out
> these corrections is *not* at the high school level, but they
> don't involve anything more than a lot of complicated
> trigonometry.  The date/place corrected formula involving these
> corrections is
>  R*F = a*(T/(2*[pi]))^2
>  where F is a fudge factor that depends on the complications.
> According to my calculations, the explicit value of F is
>  F = cos^2(D) + sin^2(L)*(cos^2(D) - tan^2(D))
>  where D is the declination of the sun on the date of observation
> and L is the local latitude of the observation.
>  The actual value of a, being only a few cm/s^2, is plenty slow
> enough for easy observation of motion of the terminator up or down
> the observing wall using a wristwatch.  To get the acceleration only
> a few timings are needed between some fiducial marks on the wall
> whose separation distance is measured.
>  BTW, in order for the method to work properly the horizon needs
> to be an unobstructed 'true' horizon that accurately represents
the
> effectively smoothed surface of the earth.  This means that the
> observation ought to be done along a seacoast or the coast of a
> great lake that can't be seen across from the top of the observing
> wall.  For those whose budgets are unlimited this means that a field
> trip to Miami Beach for the purpose of observing the sunrise on the
> beachfront hotels would make a very nice educational experience.
>  David Bowman
> ___
> Forum for Physics Educators
> phy...@carnot.physics.buffalo.edu
> https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
> 
>   


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