RE: Shadow Tapering
Hi Patrick, John C and the List, The problem of the shadow not properly filling the noon gap is the same umbra/penumbra related one which affects the reading accuracy of dials with 'solid' gnomons at all times of the day. This is usually ignored by dial makers but I know of one historical example where the maker seems to have offered a possible solution. An article by Vicki de Kleer (BSS Bulletin 19(iii), pp.116-117, September 2007) describes an 1890 brass horizontal dial made by the London maker Charles Baker for Sumburgh in the Shetland Islands at latitude 59 degrees 52 minutes N. The dial has a comprehensive Equation of Time table engraved around its periphery and also the two intriguing instructions: "AM Sub.[tract] 1 min" and "PM Add 1 min". It seems to me that these instructions are implying that the true time is being indicated slightly further into the penumbra area of the shadow than the observer might normally expect. With a dial so far north, the effect of 'shadow tapering' will be more prononounced than on most other dials. Does anyone have a different interpretation of these instructions, or know of other dials wich have similar ones? Regards, John Davis Patrick Powers <[EMAIL PROTECTED]> wrote: > If you make the dial with a tublular gnomon, and you design the face so that the time is read from the center of the shadow instead of the edges of the gnomon's shadow, then you eliminate the Noon Gap. Do you think this is the best solution? < >From the point of view of an accurate dial, one that can be calculated and one that members of the public can read easily, I am certain that it is. I have designed two 12m (or so) diameter dials this way and, by a proper choice of gnomon diameter the shadow is very easy to read. Indeed, if you want a bit of fun, if you have Google Earth and care to type in 52 45' 16.28"N, 01 08' 12.33" W then you go directly to the second of these dials. It's in Barrow-on-Soar in Leicestershire, UK. The time can even be read from space (well, with good magnifcation it can ). Google Earth's imaging is so good that I have even thought of trying to calculate what day that photo was taken - though I haven't done so yet. (If anyone wants to try, the gnomon length was such that the shadow on the summer solstice just touches the outer diameter of the chapter ring which is just inside the 'mini-stonehenge' like stone circle). Regards Patrick --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Shadow Tapering
Hi ChiLian, That's very interesting - I haven't heard before of a dial delineation being "pre-distorted" in this way to allow for the penumbra effect. Perhaps the reason that the 1 minute correction that you adopted was too much is that your latitude (24.79 N) is so much less than the Shetlands at nearly 60 degrees N. Hence the shadow is much closer to the gnomon edge and the penumbra effect is less marked. It is a complicated problem as human eyesight does not respond linearly to varying intensity levels. Regards, John -- Chiu ªô,Chi lian <[EMAIL PROTECTED]> wrote: Hi! >An article by Vicki de Kleer (BSS Bulletin 19(iii), pp.116-117, September 2007) describes an 1890 brass horizontal dial made by the London maker Charles Baker for Sumburgh in the Shetland Islands at latitude 59 degrees 52 minutes N. The dial has a comprehensive Equation of Time table engraved around its periphery and also the two intriguing instructions: "AM Sub.[tract] 1 min" and "PM Add 1 min". < I designed an 8m sundial with solid gnomon for Nat'l Tsing Hua University (Hsinchu, Taiwan, 24.79N, 120.99E) in April, 2006. I noticed the problem of shadow. No one can tell where the shadow starts or where it is perfect. That means no one can really deside by his bare eyes where the middle of the penumbra is. Most people read the dial by the shadow edge and never care about the middle of the penumbra. So I decided to use perfect shadow as time indicater. I took the "one minute off" policy since the full sun angle is about 2 minutes. The policy was "mark the hour lines one minute ahead in the morning hours and one minute behind in the afternoon hours". That is to draw 9:01 line and mark it as 9:00, to draw 2:59 line and mark it as 3:00. So the sundial was done. However, it turns out that "one minute" off is too much. I overlooked the fact that the sun, as a light source, is not square but circular. Regards, ChiLian 2008/2/10, JOHN DAVIS <[EMAIL PROTECTED]>: Hi Patrick, John C and the List, The problem of the shadow not properly filling the noon gap is the same umbra/penumbra related one which affects the reading accuracy of dials with 'solid' gnomons at all times of the day. This is usually ignored by dial makers but I know of one historical example where the maker seems to have offered a possible solution. An article by Vicki de Kleer (BSS Bulletin 19(iii), pp.116-117, September 2007) describes an 1890 brass horizontal dial made by the London maker Charles Baker for Sumburgh in the Shetland Islands at latitude 59 degrees 52 minutes N. The dial has a comprehensive Equation of Time table engraved around its periphery and also the two intriguing instructions: "AM Sub.[tract] 1 min" and "PM Add 1 min". It seems to me that these instructions are implying that the true time is being indicated slightly further into the penumbra area of the shadow than the observer might normally expect. With a dial so far north, the effect of 'shadow tapering' will be more prononounced than on most other dials. Does anyone have a different interpretation of these instructions, or know of other dials wich have similar ones? Regards, John Davis Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Monumental Sundial; 14 missing seconds
Dear Frank, Chris and the List, An experiment to determine the position of the shadow edge was reported by Allan Mills in his article "Sunlight and Shadows - or, what's the point of big sundials?", British Sundial Society Bulletin 96(1) pp.22-27 (February 1996). Allan's key result for the question now under consideration is: "the perceived edge of the 'optimum shadow' corresponded to a point where just a little of the sun remained uncovered. .. but correspond to about 12% of the Sun's diameter being uncovered." Allan's paper considers the circular shape of the light source, the effects of limb darkening and background illumination, and the non-linear response of the eye. I haven't tried the calculation to convert the 12% into a time offset. Regards, John -- Chris Lusby Taylor <[EMAIL PROTECTED]> wrote: Dear Frank, Try as I might, I can find no published information on where people judge the edge of a shadow to be. It would certainly be an interesting experiment. As John Davis observed, the human eye is very non-linear. Experience with photography seems to suggest that, like the ear, it is logarithmic. I imagine one's judgement of a shadow would to some extent depend on how clear the sky was and might well vary from person to person. For instance, someone well experienced with the phenomenon might have trained themselves to judge the 50% point more accurately. My own informal experiments with a shadow sharpener suggest that I tend to judge the edge at about 10% of full illumination, which corresponds to about 70% of the 64 seconds passed, or 45 seconds, but it may depend on a lot of factors including the colour and optical qualities of the surface - white matt paper v polished brass, for instance. One point you make that I don't understand is that you expect different results going from dark-to-light than light-to-dark. Why should that be? Shadows move so slowly that I'd imagine one would err towards the darker side consistently regardless of whether the dark area is shrinking or growing. Regards Chris --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Latin help
Dear SML colleagues, Some help, please, from the classicists amongst you. I want to put my name and that of the client on a dial that I'm making. I will have "J Davis fecit" so what is the latin for 'commissioned it' or 'had me made' to go with my client's name? Thanks in anticipation. ohn --- --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Latin help - thanks
Dear colleagues,
Many thanks to all those of you who sent me suggestions for a latin version
of "had me made" to put on the dial I'm designing. The dial will be in
vitreous enamel so, as I'm not doing all the making personally, the 'fecit' tag
against my name is not entirely appropriate. The suggestions I've compiled are:
J Davis fecit
J Davis excudit
J Davis excud{.
J Davis delineavit
J Davis delin{.
A&P Douet me fieri fecit
A&P Douet mandavit
A&P Douet commisit
A&P Douet mandatum dedit
A&P Douet mandatum detulit
I will let the clients have the final word!
Regards,
John
---
---
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Change of email
Dear sundialling colleagues, Due to a problem at my ISP, I have had to abandon my email address as printed in the BSS Bulletin. My new address is [EMAIL PROTECTED] If anyone has sent me a message in the past week, please could you resend it to this address. Apologies for the inconvenience. John Davis BSS Editor --- Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: sundials in art, literature, music, and advertising
Dear Sara, Sounds like an interesting project! There have been numerous "artistic" sundial depictions in the British Sundial Society's Bulletin over the years, such as the sundial wine label on the Contents page of issue 19(iv), or the two from the advertisements of the clockmakers JW Benson on p.172 of the same issue. Have you been through the back issues looking for them? Regards, John Davis BSS Editor Sara Schechner <[EMAIL PROTECTED]> wrote: Dear Fellow Dialers, As research for a talk and book, I am seeking images of sundials in art, literature, music, or advertising. My aim is to explore the iconography of the sundial in diverse media over a long range of time. The sundial in the picture might be central to the message of the work of art (as in an emblem or exhortation not to waste time), or it might be clustered with other objects (as in a scholar's study or with instruments trampled by war), or it might be off to the side as a piece of romantic background furniture (as in a garden scene with lovers or on a wine label).What I am not interested in for this project are plates from dialing books showing the mathematical construction of dials. However, the ornamental title pages or frontispieces of such works can have vignettes of people using a dial, and these would be of interest to me. Also at the NASS meeting in Seattle, we were treated to some sundial music from the early modern period. It was wonderful. I would be grateful to anyone who has the titles, lyrics, or music to send copies to me. If you wish to send me your replies off list in order to include jpegs, please do so. I promise to share the fruits of this search with the list when the project is done. Thanks for your help! Sara -- Sara Schechner, Ph.D. David P. Wheatland Curator Collection of Historical Scientific Instruments Department of the History of Science Harvard University, Science Center 251c 1 Oxford Street, Cambridge, MA 02138 http://www.fas.harvard.edu/~hsdept/chsi.html Tel: 617-496-9542 Fax: 617-496-5932--- https://lists.uni-koeln.de/mailman/listinfo/sundial Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Nun Appleton Dial Mystery
Hi John,
It's quite common for old (and even not-so-old) photos to be inadvertently
printed in reverse. There was an example quite recently of a dial on a glass
lantern slide printed in reverse in the BSS Bulletin. And there is a modern
dialling book with a famous painting reversed...
On the other hand, looking at a stained glass dial from the outside, even
when held up to the light, produces quite a different view to the proper inside
appearance, mainly due to the painting.
So, for this case, I suggest that it it the picture that's reversed, not the
dial.
Regards,
John
-
John Carmichael <[EMAIL PROTECTED]> wrote:
Hi All (esp. John Davis, Mike Cowhan & David Brown):
I just noticed something odd about the very famous stained glass sundial that
is known as The Nun Appleton Dial. I dont know why I never saw this before.
It slipped by right me.
Take a look at this graphic of two photographs:
http://www.advanceassociates.com/Sundials/Stained_Glass/sundials_files/Stained_Glass_Sundial_6.jpg
On the left is a close-up color photo of the dial. This photo, as with most
of our SGS photos, presumably shows the dial as it would have looked from
inside the building. The inscriptions and numerals all look corrected and were
made to be read from the inside of the building. On the right is old black &
white interior photo showing the dial as it was mounted in the transom above
the door. But look at the dial. It is backwards!
Why is this?
Im thinking that it was incorrectly mounted in the transom. It was mounted
in reverse. But it just might be possible that it was mounted correctly and
that the old black and white photo is reversed! I copied that photo from a
captured freeze frame still shot from an article by Hans Behrendt called "Alte
Englischen Fenstersonnenhren (II)" 1990. Could it be possible that the
printers that Hans used might have accidentally reversed the photograph?
Which leads me to ask if any of you ever saw this dial in its original
location above the door at Nun Appleton Hall, York, England. If we could only
find another photograph or testimony from somebody who saw it. It no longer is
there and I dont know when it was removed. It now resides in lightbox for
display at entrance to York Art Gallery.
Can anybody help me solve this mystery?
Thx
John
p.s.
Here is the information we have on this dial:
The Nun Appleton Dial
Maker: Henry Gyles (1645-1709)
Date: 1670
Original Location: Nun Appleton Hall, York, England.
Present Location: in lightbox for display at entrance to York Art Gallery.
Orientation: south
Size: unknown (large)
Adornment: Cupid holds small sundial. Small landscapes with The Four Seasons.
House rebuilt by Sir William Milner whose arms are on a corresponding pane of
glass.
Mottos: Qui non est Hodie (Who is not today). Lines from Ovid: Poma dat
Autumnus, Formosa est messibus Aestas, Ver praebet fores, Igne levatur hiems.
(Autumn gives fruits, Summer fair with corn appears, Spring bestows flowers,
Winter fire cheers).
Condition: excellent
Comment: From a print by Titian. In dark corner of gallery and back lit with
unmoving electric light.
Article by Christopher Daniel (5 MB): (Apr 1988) Stained Glass Sundials in
England and Wales. "Clocks" 10, 30-37
Article by Christopher Daniel (2 MB): (1987) Shedding a Glorious Light.
"Country Life" 181, 72-75
Original Photos: Here, Here, Here
Left Photo: shows dial mounted on lightbox at the gallery.
Right Photo: shows dial above entrance door at its original location. This poor
quality photo and some of this information are copied from an article by Hans
Behrendt called "Alte Englischen Fenstersonnenhren (II)" 1990.
Drawing by Gatty, "The Book of Sun-Dials": Here
Website: York Art Gallery
John L. Carmichael
Sundial Sculptures
925 E. Foothills Dr.
Tucson AZ 85718-4716
USA
Tel: 520-6961709
Email: [EMAIL PROTECTED]
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 & Turrets:
http://StainedGlassSundials.com/CupolaSundial/index.html
---
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Dr J Davis
Flowton Dials---
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RE: Solar synchronizer (Andrew Pettit)
Dear colleagues, You may be interested to know that the 3-D cam for the EoT mechanism (looking like a piece of modern sculpture) was on show at the 2008 BSS Conference at Latimer. A photograph of it is in the report of the conference in the BSS Bulletin, 20(ii), June 2008. Regards, John Davis John Goodman <[EMAIL PROTECTED]> wrote: The equation of time is not ignored by the Long Now clock. In one of their FAQs they state: > The clock is projected to be accurate to within one day every 20,000 > years, but just in case it isn't, a solar synchronizer will correct > the time shown on the clockface. A lens on top of the clock will > advance or retard the display by phase-locking to the local noontime > sun. The digital mechanical design also allows the clock to adjust > for leap days, leap years, leap centurieseven for the precession of > the equinox The mechanism for accommodating the EOT is described and pictured here: http://www.longnow.org/press/articles/ArtSoftwareDev.php#sidebar Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
September BSS Bulletin
Dear Dialling Colleagues, I'm pleased to inform you that the September issue of the BSS Bulletin has been dispatched to all our members. The contents list for the issue can be seen on the BSS website (http://www.sundialsoc.org.uk/) - navigate to the Bulletin page from the left hand side of the home page. A sample article is available for free download (together with a selection of articles from earlier issues) to whet your appetite. Regards, John Davis BSS Editor - Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Latin mottoes
Dear dialling colleagues, I'm currently studying Henry Wynne's 1682 double horizontal dial at Wrest Park. I haven't been able to get a good translation of all the mottoes - an unusual number for a relatively early dial. They include: "Omnia fert aetas, secum aufert omnia secum" (I believe the first phrase is 'Time brings all things', from Virgil). (Note some confusion between 'f's and the long-s possbile here) "Minuta sunt quae Spectas, non quae Perdis" (Gatty has a version starting "Minutae" (pl.) which she translates as 'what you look at are minutes, not what you lose') "Tenere non potes" (Gatty gives 'You can avoid wasting a day, you cannot hold it") Can any classics scholars do better, please? Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Latin mottoes
Dear Tom, Mike, David, John S et all, Many thanks for the translations - I am getting the gist of what the 17th-century maker and owner of the dial may have been thinking. I have now found a better photograph of the dial taken in the 1960s when it was last restored. They make two of the mottoes, which are on the top edge of the gnomon, clearer. In motto one, you are right that the comma is indeed after the first 'secum'. On motto 3, there are three extra words right at the bottom. In full it reads: Tenere non potes: potes, non perdere. I wonder if that adds significantly to the meaning? (Note: the mottoes are written in script, rather than capitals). Regards, John --- Dr J Davis Flowton Dials --- On Thu, 18/9/08, Tom Kreyche <[EMAIL PROTECTED]> wrote: From: Tom Kreyche <[EMAIL PROTECTED]> Subject: RE: Latin mottoes To: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Cc: "'Mike Kreyche'" <[EMAIL PROTECTED]> Date: Thursday, 18 September, 2008, 10:30 PM Here are a few comments from my brother Mike Kreyche, who is not on the list: 1) OMNIA FERT AETAS SECUM, AUFERT OMNIA SECUM Ditto on the comma (from David Brown’s post): "Time brings all things, takes away all things" Cited here on page 215 (a collection of German proverbs translated into Latin, published 1879--I think only the first part is found in Vergil, who was no doubt the inspiration for the wording of the translation): http://books.google.com/books?id=nPC0fjDpVjMC&pg=PA215&lpg=PA215&dq=%22Omnia+fert+aetas%22&source=web&ots=H9pqtPBhy8&sig=q5BT79K323h9OX07rMkOlOrRnS8&hl=en&sa=X&oi=book_result&resnum=9&ct=result 2) MINUTA SUNT QUAE SPECTAS, NON QUAE PERDIS The Latin is cited (with minutae) on a blog with many other Latin sundial phrases, translated into Spanish: http://cortaopeloefaiteunhome.blogspot.com/2007_01_01_archive.html The Spanish translation takes minutae to mean minutiae rather than minutes, which I'm not sure is justifiable. In any case the Spanish sounds awkward to me and I think I would have to take it as a reproach, "What you are watching are minutiae, what you're missing is not" (i.e., "why are you wasting your time watching the clock"). If the Latin minuta could be taken to mean "small things" or "details" or "minutia(e)" as well as "minute" maybe there's a double meaning. Literally, the translation is: "Details/Minutes are [things] which you observe, not [things] which you miss" Turning this into injunctions: "Details are to be observed, not missed" "Minutes are to be watched, not wasted" 3) TENERE NON POTES "You can't hold on to it" From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, September 18, 2008 4:01 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: Latin mottoes Dear John and all the rest Herewith some translations kindly supplied to me by my former classics teacher, Michael Bishop, now in his 80's but who thoroughly enjoys a puzzle or three. 1) OMNIA FERT AETAS SECUM, AUFERT OMNIA SECUM [I suspect the comma should follow the first 'secum']; lit: time/ brings/ all things/ with itself, takes away/ all things/ with itself . sc.: Time brings everything in its train, and with its train sweeps everything away. 2) MINUTA SUNT QUAE SPECTAS, NON QUAE PERDIS: lit: minutes are what you look at, not what you lose. sc: think of the passing moments as gifts experienced rather than fleeting things lost. [This reminds me of the derivation of 'minute' from 'minuere', to divide up: the ' hora minuta' being the hour divided into sixty, the 'second' being the 'hora minuta secunda' (from 'sequi', to follow), the subsequent division of the already divided hour. It also reminds me of the mynah birds in Aldous Huxley's utopian ' Island ', trained to sing 'Here and now, boys!'] 3) TENERE NON POTES [the shortest and hardest!) Lit: you can't keep hold. sc.viz [I suppose]: Time doesn't stand still - i.e tempus fugit (flees, eludes you ,rather than 'flies'). What deep philosophical musings sundials arouse! David Brown, Somerton, Somerset, UK--- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Latin mottoes
Hi Mike (and Tom, David et al), Thanks for the additional translation. I hope I might paraphase it as: You cannot hold it [time]: you should not waste it. Regards, John -- Dr J Davis Flowton Dials --- On Fri, 19/9/08, Mike Kreyche <[EMAIL PROTECTED]> wrote: . I have now found a better photograph of the dial taken in > the 1960s when it was last restored. They make two of the > mottoes, which are on the top edge of the gnomon, clearer. > In motto one, you are right that the comma is indeed after > the first 'secum'. On motto 3, there are three extra > words right at the bottom. In full it reads: > > Tenere non potes: potes, non perdere. Ah! That makes it more fun! "Hold it you can not; waste it not, you can" Mike P.S. I expect the list will not accept the message from me, so someone will probably have to forward it. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Satellite Antenna Sundial
Dear Josef and dialling colleagues,
Thank you for this most interesting information.
I actually made a satellite dish sundial in 1999. The story was published in
the British Sundial Society Bulletin, 11(ii), pp.77-80 (June 1999). I even
used the same motto - Carpe Diem - as is on one of the two commercial
versions. I should have patented the idea!
I believe the commercial dials probably have adjustable gnomons. Whilst the
hourlines should also change with the location of the dial and which satellite
it is aligned to, it probably is not too inaccurate to have a fixed set of
lines for a small geographic area. One of the advantages of the geostationary
orbits of broadcast satellites is that they are mainly in quite a small portion
of the sky.
I would be most interested in any further information you can obtain from the
manufacturers.
Regards,
John Davis
-
Dr J Davis
Flowton Dials
--- On Thu, 27/11/08, Josef Pastor <[EMAIL PROTECTED]> wrote:
From: Josef Pastor <[EMAIL PROTECTED]>
Subject: Satellite Antenna Sundial
To: "'Sonnenuhr (Uni Köln)'"
Date: Thursday, 27 November, 2008, 11:51 AM
Dear Dialists,
the "German Satellite TV Sets - producer" FUBA from Muenster/Westphalia offers
actually a special edition of "parabolic sundial satellite antennas". Two
versions are available. These have an diameter of 85 cm. For the technical
details look at:
http://shop.fuba.de/index.php?cat=c1816859_85-cm-Klasse.html
#yiv39947952 st1\:* {
}
_filtered #yiv39947952 {
font-family:Wingdings;}
_filtered #yiv39947952 {
font-family:Comic Sans MS;}
_filtered #yiv39947952 {
font-family:Wingdings 2;}
_filtered #yiv39947952 {margin:70.85pt 70.85pt 2.0cm 70.85pt;}
#yiv39947952 P.MsoNormal {
FONT-SIZE:12pt;MARGIN:0cm 0cm 0pt;FONT-FAMILY:"Times New Roman";}
#yiv39947952 LI.MsoNormal {
FONT-SIZE:12pt;MARGIN:0cm 0cm 0pt;FONT-FAMILY:"Times New Roman";}
#yiv39947952 DIV.MsoNormal {
FONT-SIZE:12pt;MARGIN:0cm 0cm 0pt;FONT-FAMILY:"Times New Roman";}
#yiv39947952 P {
FONT-SIZE:12pt;FONT-FAMILY:"Times New Roman";}
#yiv39947952 SPAN.SpellE {
}
#yiv39947952 DIV.Section1 {
}
Best regards
Josef Pastor
___
---
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---
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Re: Leap second is back
Hi Fred, Thanks for this. Whilst it's good news that there will soon be another leap second, the article didn't make it clear (to me) that the longer-term proposal to stop leap-seconds has been abandoned. So might we be cheering too soon? Regards, John -- Dr J Davis Flowton Dials --- On Tue, 9/12/08, Fred Sawyer <[EMAIL PROTECTED]> wrote: From: Fred Sawyer <[EMAIL PROTECTED]> Subject: Leap second is back To: "Sundial List" Date: Tuesday, 9 December, 2008, 11:52 PM The Leap second is back - evidently the current administration's proposal to eliminate them has not been adopted. http://www.universetoday.com/2008/12/09/leap-second-to-be-added-to-world-clocks/ --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
December Bulletin
Dear Dialling Colleagues, The December edition of the BSS Bulletin is now being posted out to members. If yours does not arrive in a sensible time (bearing in mind the Christmas rush) please let me know. Apologies for being slightly late - we have moved to new printers to allow us to go to full colour throughout. As usual, the complete list of contents is now on the BSS website (www.sundialsoc.org.uk and follow the Bulletin link) and a sample article is available for free download. Happy Christmas reading, John Davis BSS Editor -- Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Earliest UK sundial?
Hi David, Patrick et al, The Roman dial at Hever Castle mentioned by Patrick is described by Ward & Vaughan in Antiquarian Horology 12(3), 307-12, Autumn 1980 (together with other dials at Hever). They recount that the dial was "probably brought to Hever by Lord Astor's father c.1920 from his house near Sorrento, though the dial appears to be made for Sicily, lat 37 N". Thus it is rather a stretch to call it an English dial! The London Science Museum have a cast. Regards, John --- Dr J Davis Flowton Dials --- On Mon, 16/2/09, dmbsund...@aol.com wrote: From: dmbsund...@aol.com Subject: Earliest UK sundial? To: sundial@uni-koeln.de Date: Monday, 16 February, 2009, 10:06 AM Can anyone tell me which is thought to be the earliest UK sundial? David Brown Somerton, Somerset, UK--- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
March BSS Bulletin
Dear dialling Colleagues, I'm pleased to inform you that the latest BSS Bulletin is currently being distributed to our members. Please let me know if yours does not arrive in a sensible time. As usual, the contents list is available on the BSS website (www.sundialsoc.org.uk and follow the link on the left to The Bulletin). In addition, one article, on a polarisation dial, is available for free download. Happy dialling, John Davis - Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Experimental Method for Earth Radius
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 > > Do not reply to this message UNLESS you want to reply to the whole list. - To unsubscribe, e-mail: rete-unsubscr...@maillist.ox.ac.uk For additional commands, e-mail: rete-h...@maillist.ox.ac.uk --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: New equatorial dial
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. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: The Eternal Sundial
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
BSS Bulletin - June 2009
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--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Isaack Symmes 17th Century Sundial
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! -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Dutch sundial
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--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Dutch sundial
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Augusta dial
Dear All, (especially in America), Anyone know anything about this dial?: http://kennebecjournal.mainetoday.com/news/local/6765882.html Regards, John - Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
September Bulletin
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
Re: Dials and clocks
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 -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Analemma origins.
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Analemma origins.
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: Copyright query
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. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: The first printed english gnomonical books on line!
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Jose Luis Basanta
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--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Denis Schneider
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 --- Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
75th BSS Bulletin
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
75th Bulletin again
Dear Colleagues, Oops - I hit return too soon! The address should have been www.sundialsoc.org.uk. Regards, John - Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: A giant non-dial for Milton Keynes??
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: BRASS ETCHING W/PHOTO RESIST
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 -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Google's Art Project and dialling
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: A 14th century sundial question from France.
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
BSS Bulletin on DVD
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: sundial on sale
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) -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
BSS Bulletin contents
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: The sundial goes to war
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 -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Ben Franklin's Sundial Coin
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! -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Two Prehistoric Portable Sundials?
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 -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
June BSS Bulletin
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: Question on a possible sundial.
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 > -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
September Bulletin
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 - Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Headline: Second Oldest British Horological Instrument Found inAustralia
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! -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Sundial and the Leap Second
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. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Equinoctial vs. Equatorial
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 -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Georg of Peuerbach
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 -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
March Bulletin
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: Does anyone have contact details, for Brian Main ?
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. -- -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
re: sundials and tower clocks
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: sundials and tower clocks
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. Secure Meters (UK) Ltd. is a registered company in England: 2199653 Secure House, Moorside Road, Winchester , SO23 7RX This correspondence is confidential and solely for the intended recipient(s). If you are not the intended recipient, you must not use, disclose, copy, distribute or retain this message or any part of it. If you are not the intended recipient please delete this correspondence from your system and notify the sender immediately. -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
June BSS Bulletin
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: making a compass
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. -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: making a compass
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Moore Sundial stolen
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: A Nodebox Sundial (for Macintosh users - only)
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 -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: St. Margareth
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
BSS Bulletin - December
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
March BSS Bulletin
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
RE: Sundial At Tower Court, Wellesley College
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. -Inline Attachment Follows- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Today's Google Banner - More
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Two sundial resources on the Internet
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Very early equal-hours quadrant discovered
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: Man Wants heliochronometer
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
BSS Bulletin
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: sundial for a blind person
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/ --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Unicode characters for degrees, minutes, seconds above the decimal point.
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
---
https://lists.uni-koeln.de/mailman/listinfo/sundial---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: azimuth lines
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Re azimuth lines
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
Isle of Wight sundials
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 - Dr J Davis Flowton Dials--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Visibly Moving Gnomon Shadows
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 kn...@uoregon.edu--- https://lists.uni-koeln.de/mailman/listinfo/sundial
September BSS Bulletin
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 - Dr J Davis Flowton Dials http://www.flowton-dials.co.uk/ BSS Editor http://www.sundialsoc.org.uk/bulletin.php--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: BOOK: Sundials: An Illustrated History of Portable Dials - H. Higton
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
December BSS Bulletin
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/ BSS Editor http://www.sundialsoc.org.uk/bulletin.php--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: SCOTTISH SUNDIAL
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
BSS Bulletin, March issue
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--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: British Renaissance and sundials
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Theatrical sundial
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: an 18th-century blue-and-gold sundial
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Altitude dials as compasses
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 --- Dr J Davis 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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Moon dial.
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 --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: equation of time
Dear Frank et al, The earliest datable dial with an EoT scale in Britain is (I believe) the 1685 double horizontal dial by Henry Wynne for Staunton Harold in Leicestershire. But Thomas Tompion had published a table for pasting in his longcase clocks two years before. The data almost certainly came from the first Astronomer Royal, John Flamsteed. Tompion himself also put EoT tables on some of his dials but he didn't usually date them - the earliest which is positively datable is around 1702 but there may be ones from the 1690s. For further details, see: J. Davis: The Equation of Time as represented on Sundials BSS Bulletin, 15(iv), pp 135-144, (2003). and J. Davis: More on the Equation of Time on Sundials, BSS Bulletin, 17(ii), pp. 66-75, (June 2005). The early scales were usually labled "Watch fast/slow" or "Clock fast/slow". Generally, it is not until the start of the 19th century that mean time is given precedence by changing the labels to "Dial fast/slow" or, sometimes, "Sun fast/slow" I would be interested to hear from list members who know of other early dials with EoT scales. I have a database of many EoT scales, both from early almanacs and from 17th and 18th century dials: it is possible to see the way in which the actual values on dials lagged behind the latest versions calculated by the astronomers. Regards, John Davis --- "Roger W. Sinnott" <[EMAIL PROTECTED]> wrote: At 11:16 AM 10/12/2005 +0100, Frank Evans wrote:>My question is: Was this, like Richardson's appendix in Mrs. Gatty's >book, a first appearance of an equation of time line? Can anyone supply >earlier earlier examples of such a line on dials either in the UK or >elsewhere?Frank and others,I think the lack of equation-of-time indicators on dials before the mid-1800s has a simple explanation:Sundial time was considered CORRECT, and the mean solar time shown by clocks WRONG (or, at least, a mere approximation).For example, I have several English almanacs for the year 1714. One of them is The Ladies Diary: or, the Woman's ALMANACK. Next to many dates throughout the year, it has phrases such as:"Watches 3 minutes, 49 seconds too fast" "Watches have gained of the Sun 2 minutes in 8 days" "Watches will be 14 min.! slower than a good Sun-dial"Another one, John Wing's Almanack, says on the cover that it contains "an Equation Table, for the rectifying Pendulum Clocks and Watches." (Unfortunately, that particular table is missing from my copy.)-- Roger-Dr J DavisFlowton Dials
Re: equation of time
Dear Sundialling colleagues, A major article on the analemma and mean time sundials by Christopher Daniel (Chairman of the British Sundial Society) is currently being published in the BSS Bulletin. Part 1 "The Equation of Time: The Invention of the Analemma. A brief history of the Equation of time" BSS Bulletin 17(iii) pp. 91-100 (September 2005). Part 2 is currently in press for the December 2005 issue and is a further 11 pages. The paper quotes 104 references. It will include a nice colour photograph of the Coster dial of c.1726 referred to by Fer and others. It is also planned to publish the two parts together as a monograph early in 2006. Regards, John Davis -Dr J DavisFlowton Dials
Re: Dial at Schloss Bad Soden
I'm still puzzled by this dial. The numerals shown run from 7am to 6 pm. If the extra numbers are put in between these and the top of the dial where the base of the gnomon is, it would show far more than 12 hours. I don't believe this is possible for any vertical dial. Have I missed something? John Davis Flowton, Ipswich, UK -- From: Tony Moss <[EMAIL PROTECTED]> To: Cc: sundial@rrz.uni-koeln.de Subject: Dial at Schloss Bad Soden Date: Friday, February 06, 1998 07:48 Klaus Eichholz replied: >Dear Tony Moss > >at the first glance it seems an astonishing curiosity. >Look twice. >1) The picture with the sun is independent and has 16 lines, which are not >used >to read the hours. >2) The scale of the figures gives the hours with the gnomon on the top of >the >edge. > >Sincerely > >Klaus Eichholz - Arbeitskreis Sonnenuhren >[EMAIL PROTECTED] >Zum Ruhrblick 5 >D-44797 BOCHUM > Dear Klaus, Many thanks for the prompt reply. It was the visual mis-match between the sun rays and the numerals you mention which drew my attention to the picture and aroused my curiosity. If you have the information to hand, and if it would not put you to any further trouble on my behalf, I would be interested to learn the declination of the dial from East/West as I would like to plot a direct frontal view of the dial to assist my understanding. (the photograph was taken at an angle.) My Atlas shows two places with this name: (which is correct?) Bad Soden at 50° 17'N & 9° 22'E 60km ENE of Frankfurt and Bad Soden am Taunus at 50° 8'N & 8° 30' E about 15km West of Frankfurt. This is just idle curiosity on my part so please ignore if any effort at all is involved. Once again thank you. Tony Moss --
Latin motto
Can you classicists out there help a poor engineer with the translation of the motto which I recently came across on a 17th or 18th century stained glass dial? It reads: SIC VITA NVLLA DIES SINE LINEA I think that's the right word order but it's just possible that "LINEA," comes before the DIES SINE - it's written on a banner. Thanks, John Davis N52 5m E1 3m
Re: plotting timelines for giant sundials
John, I currently have a similar problem of helping to delineate a large dial, this time a vertical decliner with a 17 foot gnomon which is to be carved directly into the wall of a tower. Needless to say, the wall is not absolutely flat. My current solution has been to build a laser trigon which will be mounted directly on the real gnomon. The protractor of the trigon is 300 mm in diameter. It has a ring of holes at 1.25 degree intervals, which corresponds to 5 minute intervals on the dial face. The laser assembly locates with a pin into this ring. The pin passes though a sliding vernier, which has 5 holes set at 0.25 degree intervals, thus allowing the individual minutes to be displayed on the dial. The precision required was achieved by drilling the holes in the protractor using an accurate rotary table clamped to the pillar drill. The alignment of the gnomon to be truely polar pointing is more difficult than drawing the hourlines - as the wall isn't guaranteed flat, there is no point of reference and its presence prevent you looking up the gnomon at the pole. My solution here is to mount a laser looking down (and parallel to) the gnomon. The laser beam hits a mirror stategically placed just below the gnomon. The mirror (first surface, optically flat) is aligned to be parallel to the equator by means of a theodolite. This theodolite is co-mounted with the laser and looks at the sun though a suitable filter. Its co-ordinates are set to values of the sun's instantaneous Declination and Local Hour Angle, obtained from a portable computer. When the gnomon is properly aligned, the laser beam reflects off the mirror and retraces its path to the laser, which is fitted with a surrounding screen to show the laser spot when it is slightly in misalignment. That's the theory - the proof will come next month! Any other suggestions welcomed. John Davis
Re: Heliograph
I am lucky enough to own a heliograph, having recently bought it from
another BSS member. It dates from WW1, and looks just like the one in Peter
Mayer's jpeg with the exception that the sighting vane is more complex, with
a set of cross wires and a fold-down vane on which the dark spot from an
unsilvered spot in the centre of the mirror is aligned.
It's described as a Mk5, and comes with its own mahogony tripod and set of
spares etc. There is a range of attachments (most in very solid brass)
included in the leather carrying bag. One of these is a duplex mirror, used
when the sun and the receiving station are in opposite directions. This
mirror, which fits on the arm were the sighting vane is in the jpeg, is
always used to direct the sun onto the main signalling mirror when the sum
of the angles of incidence and reflection is 90 degrees or more. The main
mirror has a slow motion screw so that the operator can track the sun during
long messages.
I have full instructions on how to set up and use, but they run to several
pages so I won't reproduce them unless anyone contacts me directly.
The accompanying book ("The Heliograph - A short history" by Alan Harfield,
pub Royal Signals Museum, 1981, ISBN 0950121835) describe achieving signal
ranges of up to 53 miles with a 5 inch mirror (like mine), and up to 83
miles to 9" and 12" mirrors. This was done in the mountains in northern
India. Heliographs were also much used in the States, for example by
General Miles in 1878/9, and there are various quotes from Geronimo, who
believed the flashes were spirits!
All I need to do now is find someone else with a heliograph, and then we can
have aconversation (after I've learned Morse!)
Regards,
John Davis
Re: A Tough One?
Mike, I encountered a similar problem in analysing the stained glass dial from Wendon Lofts. Assuming that there are no signs of the gnomon support to define the sub-style angle on your dial, I would get a value of the declination from the asymmetry of the "earliest" and "latest" hour lines on the dial. Then, having measured all the hour (and half- and quarter-hours if they exist), I would plot y = hourline angle - LHA vs x = LHA. This should give a curve which starts at the origin, rises to a peak, then returns to zero at LHA = 90 degrees (this for the case of a direct south dial - the curve will be offset for the am and pm halves for a decliner). This experimental plot can then be compared to a series of theoretical ones calculated for different latitudes eg by the BSS Sundial Constructor program. The closest fit tells you the latitude of your dial. The advantage of the rather strange-looking x-y parameters that I have suggested is that it (a) it makes use of all the hour line information you have, (b) it is most sensitive to lines around 45 degrees, and (c) plotting the difference between hourline angle and LHA maximises the differences between curves for different latitudes. You may have to iterate around the above loop a couple of times if there is significant uncertainty as to the declination. I hope this helps - I have the Excel plots from the Wendon Lofts dial if they are of any use. John Davis
Re: Laser Trigon
Hi Alexei, I have built a "lightweight laser trigon" from a laser pointer and some scraps of perspex. As well as producing hour lines and declination lines on arbritrary surfaces, the trigon also has an attachment that allows it to project analemmas about any hour line. I have written up the instrument, and am expecting the article to appear in the next (October) issue of the British Sundial Society Bulletin. I supplied some pictures of the instrument to Bob Terwilliger, which he said he may add to his own version on his web pages: http//www.shadow.net/~bobt/trigon/trigon.htm Regards, John Davis
Re: More on Metal Sundial Processes
Tony, Great stuff! Can you give any indication of how much currect is needed (per square inch of object?). Also, have you ever tried masking some areas of the film ( hour numbers) before the dying process, so that they come out a contrasting (or clear) colour? Cheers, John - Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
Re: Making Metal Sundials II
This is real cookery! As an alternative to etching face down in a flat dish, it is simple to use a vertical tank as supplied for etching PC boards. These are tall and very thin - about 1.5 cm wide, and big enough to take the plate that is being etched. Easy to make with two sheets of perspex spaced apart and sealed with silicone. Agitation is provided by a steady stream of air supplied to a perforated tube in the bottom of the tank by an aquarium pump. A heater, again of the sort to stop your tropical fish freezing, gets the ferric chloride to a usable 40C. The key is to get a good quality photoresist that doesn't fail - the aerosol type has a very limited shelf-life, I've found. Cheers, John -- Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
A Sundial Glossary
Dear Dialling Colleagues, The British Sundial Society (BSS) has decided that a Glossary of dialling terms would be a good idea. It would have two main purposes: - to provide a refererence source for newcomers to dialling, and - to try to set preferred definitions of the terms, symbols and descriptions which we all tend to use rather loosely. I volunteered to edit such a document, and have now produced a version which is ready for review. Although the document is aimed mainly at BSS members (who live world-wide, of course) and thus concentrates on British oriented aspects, it is hoped that it will be of use wherever diallists use the English language. It is also expected that the Glossary will be useful alongside the NASS FAQ project, when that is ready. As well as a "dictionary" section, the document contains a preferred set of mathematical symbols, some contentious sign conventions, and a brief "chronology" of dialling. The Glossary has been written in a form which will be printed for BSS members. It is also hoped that it will be put on the BSS web pages in the future, after BSS members have debated its contents and agreed on correct definitions. In the meantime, it can be viewed on my rudimentary web site at: www.btinternet.com/~john.davis I'd welcome any feedback, and am quite willing to be over-ruled on choices of symbols etc, if there is a general consensus. PS - Netscape users will see some odd formatting - blame Bill Gates, because it was converted from Word97 and is fine in MS Explorer! Over to you! John -- Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
Anodised Sundials
Hi Tony (Moss), Just thought I'd let you know that I'm underway with some anodising experiments (better than Xmas shopping, anyway!). By following your instructions, I've succeeded in getting a nice yellow finish on a 10x10cm square of "aluminium". It's clearly an alloy of some sort, but I don't know its origin. I was limited by the fact that it was pulling 6 amps at only 8V - the max current of my homemade power supply and the output transistor was getting too hot to touch, so I ended the run after only 15 minutes. By halving the size of the cathode (originally 2 pieces 150 x 150 mm of aly alloy, one on either side of my icecream tub bath, I've got the current down to 3 1/2 amps and the voltage up to 14 V, so this should be better. I know where I can lay my hands on a 40 A regulated supply that I made for someone years ago, so I shouldn't be limited there in the long run. Ony partial success on the masking front so far. I've made your spray paint technique work but I'm limited in the shapes I can produce in it to lines and simple masking tape cut-outs. Etch-resist pen applied after the caustic soda step floated off after a couple of minutes in the sulphuric acid, so I'll need to keep experimenting. You weren't kidding when you said you need good ventilation, were you! Thanks for your guidance - hours of endless fun to come before I get to an actual dial, I think. Best regards, John -- Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
Re: Solstice Perigee
Roger, I'm not sure of the exact time of Full Moon, but according to my Psion the declination at midnight will be 19deg26min. I hope that helps! John Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
