Talk:Sundial/Archive 1

diptych

(moved to Talk:Diptych)

Illustrations

Sundials are beautiful, and illustrations are most welcome, could we try to be more accurate with the descriptions. So far we have a direct south vertical dial at St Remy en Provence, Latitude ?, (42 N) but this is labelled Wall dial. We have a South West decliner in Warsaw, no details, A dial in Rostov 47°13′N 38°55 (Taganrog) but no details as to whether it is set for 45N or 47N and how. Recife (more details needed) Pekin(more details). Is sundial detail needed? Why? The Prague dial 50°05′N 14°25′ looks as if it is decliner so the wall is not due E, if it were the hour lines should be 50°05′ hese look like 60?ClemRutter 11:08, 2 March 2007 (UTC)

A minor curiosity, but the animated image at http://en.wikipedia.org/wiki/Image:Equatorial_sundial_topview.gif begins rapidly, but slows down to a crawl as the day progresses. That may reflect the subjective experience of many of us, but the reality is that for all practical purposes the earth turns on its axis at a uniform rate. GardenQuad (talk) 09:17, 26 September 2008 (UTC)

Analemmatic sundials

Re-reading this section using the criteria 'Does it inform me' and 'Would it inform me if I hadn't seen previous versions' I am having serious problems with the description in the paragraph starting The geometrical construction of an analemmatic sund...

a'b' a is gobblydegook

terms like ring haven't been defined, what is a "12"

reference is made to the user's head as the gnomon, a paragraph before the users head is introduced.

ClemRutter 10:43, 21 February 2007 (UTC)

Yes, that paragraph is very badly written. Nothing in it is strictly speaking 100% wrong, just VERY misleading. For example, while the term "analemmatic sundial" might refer to using analemmas, the fact is that this term is used in the literature almost universally to describe the type of sundial using projections of the armillary sphere other than along the world axis. Because of that these sundials must use a moveable style pointing in the direction of the projection. Typically the relevant projection is vertical, hence a vertical movable style and the armillary equator showing as an ellipse on the face of the sundial (ground, typically). The term "analemmatic sundial" has become virtually synonymous with this last type of projection (vertical movable style + ellipse).

Another confusion is when the paragraph says "The month squares are arranged to correct the sundial for the time of year". Given the discussion immediately preceding this sentence, the context suggests (wrongly) that the positioning of the month squares corrects for the equation of time. This is wrong, of course, as the squares only correct for Sun's varying declination throughout the year. There is a way to correct for the equation of time by cleverly rearranging the angle of the style and its position but it applies only to a very special projection: along the equatorial plane, so that the dial itself (the ellipse) collapses to a line segment. It's a very pretty mathematical/geometrical trick devised (AFAIK) only in 1997 by Yvon Massé. It might be worth mentioning it in some future version of this (hopefully totally rewritten) paragraph. --JanBielawski 20:12, 21 February 2007 (UTC)

I suspect that the problem is that we need two entries here to serve two distinct audiences.

Sundials

Mathematics of Sundials

At the moment mathmos are distorting their style to create a bland article, which is then being hacked by the (what is a kind PC term for innumerate? ) literati to make the whole think readable. With the two article solution we can leave the Sundials article, to give a vague hint to the maths but discuss the aestetics in great depth. In the Mathematics, we can write about sines and cotangents and projection, and illustrate with Logo programs and spreadsheet macros. Then I want to know more about Yves Masse! Has anyone got any further thoughts? --ClemRutter 20:39, 21 February 2007 (UTC)

I didn't mean to make the paragraph mathematical — just to make it conform to the standard terminology in the "literary" sense. As for Yvon Massé, I don't know who he is either but I read his two papers last week and was impressed by the cleverness of the idea (or two ideas, as he gives two different constructions). I decided to write computer programs for plotting these sundials, need few more days to finish them up. [Update: the program is finally at http://a1.homelinux.com/cgi-bin/msundial2.cgi] (I'd like to try them out while the equation of time is still quite large!) Massé's two articles are at http://perso.orange.fr/ymasse/gnomon/anmnprc.htm --JanBielawski 01:20, 22 February 2007 (UTC)

I wonder if there's anything in this section, or either diptych to pull out and or xref to Analemma calendar. --Belg4mit 00:30, 11 March 2007 (UTC)

Vertical sundials

This section seems to cover a subset of all vertical dials, ie South facing dials, no mention is made of a East/West facing dials, or vertical decliners which cover the non cardinal points of the compass. Comments like although rare in modern life can't be justified, these are based on locality. In Southern France they can easily be seen. ClemRutter 10:43, 21 February 2007 (UTC)

Reflecting Dials

I question attribution to Newton b1643, when Waugh says that Christopher Wren b1632 had a similar dial when he was 16. ClemRutter 10:43, 21 February 2007 (UTC)

I've added a 'citation needed' to this section. What sources tell us that Newton had a reflecting sundial? Ferkel 14:05, 28 March 2007 (UTC)

I mentioned the source I have above 'Waugh' refered to in the article in References, as Sundials: Their Theory and Construction, Albert E. Waugh, Dover Publications, Inc., 1973, ISBN 0-486-22947-5. (page 116)

My problem with this is that he quotes no source, though gives the clue it was in his grandmothers house- Newton experts will probably have the source, but I class this as authoritively quoted hearsay! and think your tag should stand. ClemRutter 00:03, 31 March 2007 (UTC)

Icarus precision Portable Sundials

http://www.nauticalia.com/uk-c/instruments/sundials/index.html Any further ideas? ClemRutter 10:43, 21 February 2007 (UTC)

equation of time, orbital eccentricity

What difference does the eccentricity (elliptical-ness) of the orbit have to do with accuracy of the sundial? As far as I can tell, this should have no effect. The tilt of the Earth reltaive to the Sun, however, should have an effect.

The earth's movement around the sun is fastest when the earth is closer to the sun, and slower when the earth is farther from the sun.

The earth revolves around the sun (360 degrees) in a year (365 days). That makes about 1 degree per day. So the earth needs to rotate on its axis about 361 degrees for the for the sun to appear on the meridian, day after day. But the earth's angle of revolution about the sun, averaging 360/365 degrees, is greater when the earth moves faster, when it is closer to the sun (perihelion), and is less when the earth moves slower, when it is farther from the sun (aphelion). So eccentricity will matter. RPellessier | Talk 20:07, 13 August 2006 (UTC)

"plekhnaton"

Anyone can confirm the word "plekhnaton"; it doesn't pass the Google test (1 entry; the wikipedia one). -- looxix 00:31 Apr 18, 2003 (UTC)

- - - The suggested method of adjusting to local time by tilting the sundial East West is incorrect, since the gnomon always has to be pointing at the pole star. See www.sundials.co.uk/setup.htm

---

ANd sure nuff, "plekhnaton" was a mistake. It is not Greek, modern nor ancient (for which see Liddell and Scott's (ancient) Greek Dictionary, online at Perseus. "Plekhnaton" puzzled a lot of us on the Sundial-List, but finally someone came up with the source of the error: a misread or mis-scan of a passage in Winthrop Dolan's 1963 book, "A Choice of Sundials", that discussed the "Greek pelekinon sundial". It is probably safer not to refer to this type by that name at all; "pelekinon" is the adjective formed on "pelekus", the common Greek word for an axe.

I don't understand what you mean by "that name". Are you recommending the name "Greek pelekinon sundial"? Or is there some other name you would prefer? --DavidCary 08:04, 19 Jan 2005 (UTC)

accuracy

This should be rewritten somehow

Traditional sundials are only accurate to about a quarter of an hour because

the Earth's orbit is a slight ellipse. Simple, quality sundials often mount a

small graph or table to give corrections from apparent solar time to the

nearest clock-time minute based on the current date.

Traditional sundials are perfectly accurate to minutes. They only show different time, true local solar time. In case of old sundials, that was the "right time" for their designers. Fact that we now use better, steady-flowing time standard kept by atomic clock, does not make old sundial less accurate.

Wikimol 20:18, 19 May 2004 (UTC)

moondial

Is there such a thing as a moondial to track the motion of Luna? --DavidCary 08:04, 19 Jan 2005 (UTC)

Why is time as it is?

Why are there 24 hours in a day? Why are there 60 seconds in a minute but 100 milliseconds in a second? —Preceding unsigned comment added by 82.24.171.240 (talk)

There are 1000 milliseconds in a second. —Keenan Pepper 00:30, 16 March 2006 (UTC)

This is a question about number bases, and the different ways that our ancestors prefered to count. Why are there twelve inches in a foot- twelve months in a year- twelve hours in a day and twelve in a night making twenty four. In the article you will see that once, there were twelve hours between dawn and dusk- so these would be shorter in winter and longer in summer. The sundial in someways is a record of how we have divided time in the centuries past.

24= 2x3X4 and 60= 2x3x4x5 which is import when you want to measure a third of a minute, or a fifth of a minute. So if you want to divide an hour into equal units, 60 is the smallest number you use that can show a fifth or third or quarter. Ideal for your minute parts. Having divided an hour that way, why not divide your minute part in second- minute minute parts.

Now the second was redefined by scientists- same length but written in a different way. Modern thought uses metre/ kilograms/ seconds- and everything is base 10. So when the second needed to be divided- it was now divided into 1 thousand parts- millimetres had shown us the way- and we have the millisecond, and the nanosecond etc. Sundials have difficulty in showing anything smaller than a minute. Hope this is what you wanted to know- follow the links and enjoy wikipedia. ClemRutter (talk) 14:16, 17 December 2007 (UTC)

One explanation for the twelve months in a year is that there are between twelve and thirteen lunar cycles in a year. See http://en.wikipedia.org/wiki/Month --Knowthhill (talk) 05:03, 20 August 2008 (UTC)

Sundial relation to latitude/ longitude

What is the relationship between your sundial and longitude/ latitude? Thanks.

Check out The Sundial Primer at www.mysundial.ca and you will find the answer.

Was this post from Carl Sabanski. He has some nice diagrams on the above site, is he willing to release them to a creative commons licen(s|c)e? ClemRutter 11:29, 2 March 2007 (UTC)

Digital sundial

Digital Sundial OK! Do not delete it - if you want to verify please click the patent link in the article or Digital Sundial Int. —The preceding unsigned comment was added by Beaumont (talk • contribs) 18:05, 19 August 2006. ...Sorry, I thought I signed it (lost in the connection?) ;) --Beaumont 21:01, 19 August 2006 (UTC)

Equatorial sundial

"In the winter, the north side of the disk will be shaded, and hard to read. In the summer, the south side will be shaded." Is it right for both hemispheres, or just the northen one (and the southern would be just the opposite)? --Mark Nez 12:56, 2 October 2006 (UTC)

Tempometer

Apparently some obscure solar time thing, with lots of mentions in reference to Cakra and Krishna.

• funky drawing
• cache of the Cherokee wikipedia page (something bad seems to have happened over there
• Astronomical clock —The preceding unsigned comment was added by Belg4mit (talk • contribs) 00:26, 11 March 2007 (UTC).

Links

Sunny Day!

I am Carl Sabanski and the creator of the web site “The Sundial Primer”. Over the past few years I have invested hundreds (four digits) of hours developing my sundial site. My site offers well over one hundred pages of information and hundreds of files available for free to anyone interested in sundials. I have had a link to my site here for a long time and have had thousands of visitors use this link.

Lately there have appeared these self-appointed “Wiki-Cops” who want control of what I thought was a forum for all. If you have the desire to be one of these then perhaps you should learn to follow the rules. If you want to have full control then start your own website.

My site offers sundial enthusiasts information that they will not find on any other site. It will offer more in the future. The point is that I will decide what page the link directs visitors to, not some “Wiki-Cop”.

And if you are a “Wiki-Cop”, do something useful. If commercial sites are not permitted, then take care of the one that is linked to from the analemmatic sundial section. If you care at all about content, here’s a real challenge. Go to the “Gnomon” page and get rid of the picture of the Sundial Bridge. If you go to the NASS site you will discover that this bridge is what I call a “wanna be” sundial. Pick a real gnomon from a real sundial. How about “The Pinawa Heritage Sundial”?

And if you “Wiki-Cops” aren’t finished with me, fine. It’s all just entertainment value. —The preceding unsigned comment was added by 205.200.32.24 (talk • contribs) 16:45, 2007 May 20.

I've reviewed Sundial Primer and it is my opinion that it complies with my reading of WP:SPAM and WP:EL, the relevant guidelines for external links. Other editors may not agree. This article seems to attract noncompliant edits, however. Please note that while Wikipedia is open to all, edits should be consistent with relevant guidelines and must be compliant with policies, or they will be removed. Best wishes, Walter Siegmund (talk) 21:17, 20 May 2007 (UTC)

Greetings Carl. If you look at the history, you will see that I have been repeatedly replacing your link when it has been removed for instance 09:27, 17 May 2007 ClemRutter (Talk | contribs) (24,114 bytes) (Replaced-this site is non-comm, the only one to give full treatment of the mathematics. I have removed POV, changed the link to index page.) IMHO the tsp page was more vunerable to wandering bots, than tsp_index hence my reversions. The difficulty I have with tsp is that the link is not obvious. The Come and visit line looks like a link but isn't, and the heading the Sundial Primer is underlined like a link but isn't, and the actual link Sundial Primer looks exactly like the heading-- then is a link- but you miss it because you have been fooled before. I actually think that this has caused some of the Wikipolice friendly fire- fifteen seconds tweaking the HTML should solve it.ClemRutter 00:19, 21 May 2007 (UTC)

SQUIDOO SUNDIAL PAGE REMOVAL Removal of squidoo sundial page: I dont know what constitutes a spam link. I do know that the Squidoo page on sundials which was removed had good comprehensive information on sundials that was, unusually for information on sundials - wikipedia included, easily accessible to all. Wikipedia it the poorer for its removal only because it was a Squidoo page regardless of the content.— Preceding unsigned comment added by an unspecified IP address (talk)

I agree with the above unsigned statement, as it happens this time the link does / did lead to useful information. I am not sure what can be done about it though? --Edmund Patrick ( ^confer _work) 16:18, 4 August 2007 (UTC)

Am I right in thinking that the user who submitted the useful squidoo sundials link (francesLey who is me) has been removed from wikipedia? Hope not but it sure looks that way. It makes the adverse comments I have read about the wikipolice seem based on some substance. Will this comment be removed too? And I am anonymous because I am on holiday at an internet cafe in spain, just in case that also offends wierd wiki rules. Oh but of course I couldnt log in anyway cos I have been removed.

To put the record straight, I, francesLey, wasn't removed. I'm still irritated though by the removal of a useful resource that offers something Wikipedia doesn't (understandable to ordinary people) and is clearly not commercial, when the sundials web ring - of little interest to anyone - remains in this page's links section. —Preceding unsigned comment added by FrancesLey (talk • contribs) 13:35, August 26, 2007 (UTC)

Benoy Dial

I have added this information to show the development of sundials. Ours at the moment is in store!! (St Edmunds) and I would be grateful if the other places listed where the dial can be seen could be checked out, and verified. Once I am better at uploading a image I will put one on the site. With Thanks --Edmund Patrick 12:04, 9 July 2007 (UTC)

mysundial.ca link

The link was added to the Meta blacklist to stop the persistent cross-wiki spamming of it (see for instance http://cs.wikipedia.org/w/index.php?title=Slune%C4%8Dn%C3%AD_hodiny&action=history). This article can't be edited as long as the link is in the article. If you want to use the link, please try to get it added to the local whitelist. If not please remove the link. The link is in these articles too:

• Equation of time
• Diptych
• Gnomon

and on this talk page: User talk:205.200.63.67

Thanks. --Jorunn 12:29, 20 August 2007 (UTC)

What on earth is the objection to Carl Sabanskis site- apart from pitiful use of HTML! It is by far the most authorative site available on the subject and is an essential link. If the problem lies with someones bot please get that sorted- but remove this destructive blacklisting it does no credit the reputation of Wikipedia. I will cross post this other sites that have referred me here. En:User:ClemRutter. 90.0.239.102 14:41, 20 August 2007 (UTC) ClemRutter 14:44, 20 August 2007 (UTC)

I removed the links now as nothing had happend since 20 August, and they the links were blocking edits to the articles from being made. A link to a mirror site and two redirect ulrs have been blacklisted too. This is all due to the links being spammed cross-wiki. If you could just not add the link to all articles cross-wiki this would not be a problem. You can make as many mirrors and redirects as you want. But if you add the links to any and all articles you find cross-wiki it will be blacklisted and that will also take effect on en.wikipedia, so don't do that if you want to keep the link here. --Jorunn 09:46, 31 August 2007 (UTC)

The link to my web site existed on many of the web sites for many months and many visitors came to my site. As far as I'm concerned my site offers more informatin on sundials than any other site in the world. My graphical sundials, sundial kits, sundial templates. etc. can be used by teachers, students and anyone else who wants to learn about sundials. I have spent hundreds of hours to make it it a useful source on sundials and there is more to come. Wikipedia is an encyclopedia, not a dictionary. What use is a single paragraph description to anyone, in any language? And if that's what is wanted then locak the page as is being done. That pretty much makes the page useless. Then you and a couple of your sidekicks came along. I don't know what your problems are and I really don't care. But now my two main sites are blacklisted because you guys need therapy. I have no desire to co-operate with you or your WikiCop buddies. --Carl Sabanski —Preceding unsigned comment added by 205.200.63.35 (talk) 16:31, 3 September 2007 (UTC)

I am very grateful that the link has been restored. (26th August). The whole episode was so unnecessary. ClemRutter 17:44, 3 September 2007 (UTC)

HMMM! I thought you said it was restored. You WikiCops are a real piece of work! Oh well...!!! —Preceding unsigned comment added by SunDoggie (talk • contribs) 00:22, 7 September 2007 (UTC)

How can we finally sort out this link. It does have difficulties but is an informative, knowedgeable site, what more does one want! I am not sure what is being done incorrectly for this to stay, can we get the bots to recognise it. Or shall we just type the address in and get people to cut & paste. at least they will get there.--Edmund Patrick ( ^confer _work) 08:27, 7 September 2007 (UTC)

Yo Jorunn! Are we having fun yet? —Preceding unsigned comment added by SunDoggie (talk • contribs) 00:42, 13 September 2007 (UTC)

tried to add a wonderful image of a 4 faced sundial and was stopped because of spamlink! Have asked whitelist to look at it and hopefully sort it. If not is it back to text link and cut and paste, with a note to explain next to it!! --Edmund Patrick ( ^confer _work) 09:54, 14 September 2007 (UTC)

I mercilessly removed it - links crossposted to many wikis are spam by definition. Do not continue posting links to your own site, please. /SvNH 02:30, 15 September 2007 (UTC)

Actually I thought the compromise of nonwiki worked. It was not a direct link but gave researcher the opportunity to look at the website by the labourious cut & paste method. So as it no longer formed a crosspost to many wikis I have re-introduced it. Edmund Patrick ( ^confer _work) 09:20, 15 September 2007 (UTC)

?!? A link, posted by the site owner on many wikis, is a link posted by the site owner on many wikis (and therefore considered spam), no matter how it is presented or to which mirror it leads. /SvNH 12:15, 15 September 2007 (UTC)

?!? An interesting concept, one can hide - loose - censor knowledge by deliberately adding a link to many pages, relevent or not, therefor it becomes spam no ifs or buts. An interesting and subtle programme. As a matter of informaion the recently removed link was not posted by the person who developed the site. It was put there as it fitted into - Any site that does (not) provide a unique resource beyond what the article would contain if it became a Featured article. remove the not and it does what it says. External_links#Links_normally_to_be_avoided Obviously the site owner has added the link to too many sites, enthusiasm could be but one reason. Oh well, I have learnt about a new tool, nothing lost. Edmund Patrick ( ^confer _work) 14:33, 15 September 2007 (UTC)

Hmm, but you don't consider e-mail spam filters censorship, do you? Note that someone has rather aggressivly posted this link (or a link to some mirror) on sv, da, de, fr, cs, no and many others, and that at least Czech and Norwegian WP have decided to protect the article from non-logged in users because of this. Also, I think the tone in the message below and those above speaks for itself. /SvNH 19:48, 15 September 2007 (UTC)

Sunny Day WikiCops!

It's interesting to note The Sundial Primer link remained on many of the Sundial pages for many months until some of you characters came along. There was no problem. Perhaps you guys were abused as kids but if that's the case get professional therapy. Don't use the Wikipedia as an outlet for your frustrations. The Sundial Primer is the best sundial site in the world and it would be remiss not to include it in the Wiki pages. So there is no need to threaten as it just doesn't matter...The Sundial Primer is here to stay. You will have to exhaust all means of this great site from being added to your precious pages before it will ever disappear. Good luck to you and your bots! Luv U! —Preceding unsigned comment added by SunDoggie (talk • contribs) 17:57, 15 September 2007 (UTC)

SunDoggie (talk · contribs) is a WP:SPA that adds mysundial.ca links to Sundial and related articles in apparent noncompliance with WP:EL and WP:SPAM. The message above violates WP:NPA. Please review WP:DR and WP:TALK to learn how to use talk pages effectively. Walter Siegmund (talk) 04:37, 16 September 2007 (UTC)

After much support for a brilliant if in ways flawed website the message above - Sunny Day WikiCops!- not only underminds me buts leaves me with the decision to withdraw support, it also ends up reinforcing the spam point of view. I thought the knowledge was the important thing. I will not try to get this link re-instated, until a noticable change if that happens. Edmund Patrick ( ^confer _work) 08:29, 16 September 2007 (UTC)

To sum up.

• Carl Sabanski has personally written the best site on the internet for anyone wishing to understand and use the Mathematics of Sundials. Call it mysundial.ca- or the The Sundial Primer. It has information about constructing many kinds of sundial, with paper sundial kits, sundial templates and "Computer Aided Dialling".

• 6 April 2004 I made my first signed posting on this page
• 21 December 2004 ip 205.200.32.28(I assume Carl) did some work on en:Wiki- he posted a link to Carls Site. It was immediately removed by User:Wikimol with the reason too many links -at the time the links he kept were to images of individual dials. 205.200.61.8 restored the link an so it has remained.
• 29 March 2005 User:Wikimolissued warning- removed -strongtags- from link (page was hosted elsewhere)
• 11 June 2005 User:Wikimol claimed mysundial was site promotion. |Itis retained.
• 15 January 2006Walter Siegmund (talk) made his first posting, editing the History section. At that time there was a link to mysundial.ca. which he left untouched.
• 16 April 2006 Walter Siegmund deletes an unrelated link, citing WP:LINKSPAM and WP:EL, leaving mysundial.ca
• 7 Sept 2006 Solur article written on Swedish:wiki. A ip 205.200.XX.XX posts the link- it is immediately removed, leaving the page with no references no links.
• 8 Sept 2006 Solur appears on Old Norsk; posted 209.167.89.139 and is blocked. The only reference to remain is one to quotations in the Bible.

The sillyness has now really started. This has resulted in a crosswiki blacklisting that is impossible to whitelist- as that part of en:wiki appears to be broken.

Can we look at some policies, because up to this point none had been violated. I hold strongly that WP:AGF and Carl had a right in 2006 to this principle. Were I to be working today on the danish, swedish, old norsk pages I would be grateful to have such a useful link added. WP:LINKSPAMis very clear that

However, it is not set in stone and should be treated with common sense and the occasional exception. When editing this page, please ensure that your revision reflects consensus. When in doubt, discuss first on this page's talk page.

Carl's site is the 'occasional exception' and can be valuably linked.

• I maintain that before declaring it spam you must read the link- check for commercial gain, here there is none- or self promotion- here Carl's name appears on the flash page and his page template,but not in the website address, indeed all his posts before this month were ip posts.
• I concede that were the content to fail those tests it would be spam- but all he has done WP:AGF is, in his generosity of spirit, used the same mechanism of delivery that a spammer would use.
• I do think he has triggered the problem by Looking like a spammer.
• It should be pointed out that Carl has always done IP posting usually from a 205.200.xx.xx address. I may be wrong but SunDoggie is his only registered name so he cannot be accused of being a Sockpuppet-but he is a specialist not a generalist.

To quote from Monty Python He's not the messiah, just a very naughty boy

• A lot of people from en:wiki and Scandinavia are devoting a lot of time WP:AGF trying to do the right thing, but I feel that all should consult WP:CIVIL so it is not breached further.

Can we get back to writing a page about Sundials and apply the fervour that we have been using to discussing a link- to writing pages with high quality links. —Preceding unsigned comment added by ClemRutter (talk • contribs) 10:52, 16 September 2007 (UTC)

I think "mysundial.ca" may be a useful source for this and other similar articles. As time goes on, it may be supplemented or supplanted by sources that better comply with WP:RS. I strongly encourage all to respect the policies of WP:CIVIL and WP:AGF. In particular, the name-calling ("WikiCops", "you guys need therapy", etc.) and threats ("the Sundial Primer is here to stay", "I will decide what page the link directs visitors to", etc.), that I see elsewhere on this page, are not useful. SunDoggie should not be editing this and similar articles in violation of WP:COI.

Moving good external links into footnotes and removing the external links section may be help reduce editorial conflict. Thank you for the helpful thoughts. Walter Siegmund (talk) 14:54, 16 September 2007 (UTC)

CONGRATULATIONS! So you clever fellows found all the link shorteners that I can use. Thanks to those who may not necessarily support me personally but do support The Sundial Primer. In the beginning I thought that I was providing a link to an abundance of useful and not readily available information about sundials and dialling. But there are those who obviously don't agree and really, at this point of the game, I don't care. I doubt that you have even bothered to visit the site. Now I just want to be a pain your in dark sides. A direct link to my site isn't necessary so I guess I'll try the indirect approach for a while until I can find another method of getting around "The Blacklist". To say the least it has been entertaining and I have learned a few things over the past little while. So on with chase! —Preceding unsigned comment added by SunDoggie (talk • contribs) 20:52, 16 September 2007 (UTC)

Vitruvius

I am uncomfortable with this posting as it stands for the following reasons.

1. It is in list format in an otherwise prose page
2. It would be more appropriate on a page called the History of Sundials in literature
3. The links don't link to a sundial description

Maybe it should be a footnote? Maybe it should be separate page? It is important material I just feel it is in the wrong place. ClemRutter 18:37, 6 September 2007 (UTC)

sorry must be late, I do not understand this, can you point me in the right direction. Thanks --Edmund Patrick ( ^confer _work) 19:25, 6 September 2007 (UTC)

Last 10 contributions, all by User:Granite07 who obviously is a gifted classicist. See History. ClemRutter 19:55, 6 September 2007 (UTC)

Thank you for the compliment but I cannot claim to be a gifted classicist, the only classic book I have read is De Architectura. Granite07 04:53, 29 September 2007 (UTC)

rested now, yes I can see your point, and I agree in the wrong place. Move to the bottom - say it is a list and over time provide an image gallery if relevant, under the History of Sundials in literature section. --Edmund Patrick ( ^confer _work) 08:23, 7 September 2007 (UTC)

Thank you, was not certain where to place list, actual links and descriptions of each type of sundial is the goal.Granite07 03:31, 9 September 2007 (UTC)

vito in moyu

This I believe is the moto on the dial face of the Norfolk 4 faced dial. I have got as far as vita : life, way of life. in : into, toward, against. OR in : in. After that I am lost. assistance please Edmund Patrick ( ^confer _work) 09:45, 15 September 2007 (UTC)

Actually vita in motu , Latin for life in motion Edmund Patrick ( ^confer _work) 11:43, 8 October 2007 (UTC)

on a lighter note

Wikipedia_talk:Userboxes/New_Userboxes#September_18.2C_2007 Edmund Patrick ( ^confer _work) 16:32, 18 September 2007 (UTC)

up to date link for those inclined! - they are, after all, accurate: Sundial user box Edmund Patrick – confer 18:39, 6 May 2010 (UTC) correct link! Edmund Patrick – confer 18:54, 8 May 2010 (UTC)

images on commons

user:ClemRutter and I have been discussing the confusion of images in commons for sundial and sundials. Me specificially because I was looking for some images. After reading Commons:Village_pump#categories where I put this point for discussion in Commons; can we all decide where to do with this. My thoughts: all images moved - categorised into Sundials and then create galleries of types of Sundials and Sundials by country. Of course it maybe me! Edmund Patrick ( ^confer _work) 17:25, 20 September 2007 (UTC)

Ring dials and nocturnals

The photo labelled "traveller's dial" made me cringe. Sorry, but as an enthusiast of antique scientific instruments, the name should be ring dial - actually Universal Equinoctial Ring Dial. There are several types of ring dials from simple rings, equinoctial rings, universal rings etc. I wonder if the section should be expanded or another page be created and linked (e.g. main article: Ring dial)?

Also, I would suggest a link to Nocturnal (instrument) in the See Also section. BTW - if anyone has a photo of a nocturnal they could put on Commons, that would be great. Michael Daly 23:52, 21 September 2007 (UTC)

I didn't notice that the page protection was only for non-logged-in users when I wrote the above, so I did the changes and added the ring dial section within the Elevation section. Michael Daly 05:31, 22 September 2007 (UTC)

Sundial Content

There are items in this article with information that is misleading as well as others that give incorrect information. Some of the text is vety difficult to follow because it is not well written and there is a lack of consistency in the use of terminology throughout the article. Many visitors will no doubt go away scratching their heads or will take away information that is wrong. Adding photos is a nice touch but someone should first fix the article so it is at least correct. —Preceding unsigned comment added by 205.200.63.71 (talk) 02:29, 5 October 2007 (UTC)

Although I know we have lost some information recently that was via a external link. Please either fix the mistakes or point out what you feel they are. Many people have been working on this article for a long time, if you can improve please do; remember be bold Thanks Edmund Patrick ( ^confer _work) 20:10, 5 October 2007 (UTC)

The changes I see that are required would take quite a bit of time to implement. It would be useful to add a few figures as well as some changes to the text but I do not have the time to do this. Also, I have been reading a little about the site and although there are rules to abide by it seems that some can be interpreted quite freely when it comes to deleting other writer's work. A lot of time can be spent upgrading this article and it can be just arbitrarily removed because someone, who may not have much knowledge in the subject, feels that it makes the article too long or, in their opinion, it does not add value. In any case, the writers can read any one of the books listed and they can easily determine what isn't quite right. Good luck. —Preceding unsigned comment added by 205.200.71.225 (talk) 23:47, 5 October 2007 (UTC)

Images

I am a bit concerned with the amount of images in the article. if I add, and I am researching this, diagrams that show the maths behind various sundails the list and article will start to look silly. Do we set up a gallery within the article (as per Charles Worth and many others) or what. Although there is some repeating in the images all do enhance the article. Maybe if the Commons:Category:Sundial is finally sorted then we could just list where to go for particular types of Sundials. Edmund Patrick ( ^confer _work) 14:16, 13 October 2007 (UTC)

I share your concern. Newbies tend to use this as a sandtray to practice uploading images to commons then making a link. But following the policy WP:BITE we tend not to do a RV. So I suggest criteria that I think we should follow.

• No images unless they refer directly to text in that session.
• No duplicates of dials of the same type. ie Direct south vertical dial.
• Images must be labelled with what they illustrate.
• Images should be geocoded, is some way in the caption as this is relevant

ClemRutter 16:38, 13 October 2007 (UTC)

Agreed Edmund Patrick ( confer  work) 09:49, 14 October 2007 (UTC)

It should be noted that there is a link to commons, and I think that this is a better way to display the hundreds of works of art extant than using a gallery. Though in this case the gallery IMHO was more appropriate.

The Dial from Cornwall/Kernow is intersting in that it displays dial furniture which we haven't discussed and looks to have a slight SW decline. (TANSED-Three Above Nine South East Decline-my mnemonic). The motto is intersting- do we need a page for Sundial mottos- maybe with illustration?

ClemRutter 16:38, 13 October 2007 (UTC)

Possible plan of action, before anything else is added

• we sort Commons:Category:Sundial
• then we can remove repeats into correct categories.
• Then we can start to add diagrams that hopefully explain some of the maths about sundials.

I like the geocoded as these will provide a clear link to the position of a sundial and the maths involved, and will also compliment any diagrams explaining the rules. Then to cap it all we go for WP:GA !!! Edmund Patrick ( ^confer _work) 09:49, 14 October 2007 (UTC)

transferring of images

Dear All, finally sat down to look at copying diagrams from de:Benutzer:Fantagu - descriptive diagrammes of the mathematics of sundials. After looking at Inkscape for converting the images to SVG. there is a little bit of advice at Commons:Transition to SVG but sadly not much, and basicially beyond my computer skils, (let alone translating skills)!. People might not agree to their worth in becoming part of the sundial page, but if they do I am willing to assist someone else. Sorry Edmund Patrick ( ^confer _work) 11:16, 16 October 2007 (UTC)

I'd never seen them before- could you tag the images as Category:Sundials so we can find them easily. Transition to SVG- needs completely rewriting- it can be done but "Übung macht dem Meister". My thought were that we need a diagram for each type- taking the Sundials: Their Theory and Construction, Albert E. Waugh, Dover Publications, Inc., 1973, ISBN 0-486-22947-5. book as source. Though Waugh is not internally consistent in his symbols. Any thoughts?

ClemRutter 13:09, 16 October 2007 (UTC)

thoughts from a collegue in British Sundial Society; The publication he mentions I do not know.

“ Re the Wikipedia project: yes, the sundial community was aware of this via the Sundial Mailing Group. Waugh is probably the best-known 'modern' dialling book but it was written in the days before calculators or computers. Because of this, all the equations are evaluated in terms of logarithms which makes things unnecessarily complex these days. Slightly more up to date is Rene Rohr's book, though that includes some more complicated dials. It is still copyright, of course. If you want someting out of copyright, you'd probably have to go back to Mrs Gatty (preferably the 4th Edition, edited by Eden and Lloyd). The 18th century texts use notation that isn't easy to follow these days.Really, though, Wikipedia ought to have up-to-date terminology and layout. It's just a case of finding a diallist/mathematician with the time ”

Time would answer a lot of questions but does anyone have an opinion on the Mrs Gatty. Edmund Patrick ( ^confer _work) 10:31, 22 October 2007 (UTC)

Drastic edits = broken links

On 13 Oct, there were some drastic edits, removing entire sections from the page without any real explanation. This has broken links from other pages that linked to the section(s) removed. Those links are now meaningless.

Rather than remove the sections, shouldn't the page be factored into another article? It seems the edits preserve the notion of the sundial as a large piece of art rather than a functional object that was used in lieu of a watch. I don't see the point in throwing information away without clearly enunciating the reason.

Such devices as ring dials may seem trivial to some, but they are documented in scientific instrument texts to a greater extent than oversized garden trinkets. Michael Daly 19:39, 18 October 2007 (UTC)

Mystery solved. The text was never removed. In the edit, partially to solve the tendency you observered, I incorrrectly closed an inline comment. So the following text was not displayed. I didn't notice it was missing. It is back in all its glory. I do think the structure is now more acceptable.

• You may like to move your Vitruvius section from further methods to History.
• I note that Vitruvius didn't explain the workings of any of his dials and think that the wikilinks need checking.
• The next stage is to get mathematical diagrams to explain each of the dials- do you think we should write a separate page- Sundial Mathematics- or place the maths in a table structure on this page. The advantage of the former is that the page is now rather long, and it could be written in more detail.

ClemRutter 22:57, 18 October 2007 (UTC)

Thanks for fixing the page. Sorry if I sounded a bit peeved. I was, but not entirely due to this apparent problem alone. :)

I don't know anything about the Vitruvius section. I may have formatted it a bit, but didn't add it. I've been thinking of adding a section on Butterfield dials - I don't know much about them other than what I've read. Not to be confused with the Ring dial constructed by the same Butterfield shown in the image.

I'd be inclined to see a new page added for sundial maths. Those math-challenged will not be put off the current article if it's elsewhere. Michael Daly 20:22, 19 October 2007 (UTC)

It was the last dozen keystokes of a 4 hour edit- I don't think at that point I was capable of seeing the screen. As I said 'mystery solved' because we actually share the same aims.

• I will shift Vitruvius.
• Butterfield dial- not familiar with it. So it must be added.
• The maths- I think a one line equation on the sundial page, and more explanation on a Sundial Maths page. All dials can be drawn IMHO using a theoretical method and also by geometric construction, both need to be covered. My problems with the SVGs are that if I copy diagrams from my sources (such as Waugh) they are rarely clear- and if I make them clear I could be accused of original research, which technically it will be. They are so timeconsuming to do. So I am still thinking about it.
• Maybe if we spawn a page- The Art of Dial Furniture, we can set up and seed a few galleries, and let the mathematically challenged loose there!?

ClemRutter 20:58, 19 October 2007 (UTC)

Butterfield dials are a type of folding pocket dial (not very similar to a diptych at all). They are notable for their octagonal case shape. They were first made by Butterfield (an Englishman in Paris) and copied by others later. Fancy and expensive in their time, I believe. folding case type National Maritime Museum Butterfield dials mostly uncased.

I have copied diagrams and drawn them to extract the essential characteristics. When posting to Commons, I state that they are my own work and "after so-and-so". This is, IMHO, equivalent to a fair use extraction and are not original work on my part. The original sources are all PD (very old typically). No one has complained yet and I don't see that it's any violation. If Waugh is copyright, I think fair use still applies if it is a drawing you make based on his documents. --Michael Daly 20:01, 20 October 2007 (UTC)

I have contacted a friend of mine in the British Sundial Society who hopefully will point me in the right direction for a source of diagrams. I do like the idea of a separate page for detailed maths, but IMHO some maths will still be needed within the article to explain what a sundial is and why some of the parts are as they are. Edmund Patrick ( ^confer _work) 12:14, 20 October 2007 (UTC)

Butterfield Dials

Within the collection I work with we have an octagonal diptych compass available with image. It has the conventional string gnomon set for different latitudes etc. it also has an altitude dial and a pin gnomon for babylonian and italian hours. IMHO it should be added but I am concerned with the amount of images and resulting text. IMHO we go for the one example of each type with basic principle of how it works formulia, image, text. The proposed new page can cover the formulia diagram etc. Edmund Patrick ( ^confer _work) 11:55, 22 October 2007 (UTC)

Quality of recent edits

I haven't time at the moment to do all the corrections: but before we get too enthusiastic, can we please remember:

• The article is about sundials not stars and astronomy.
• Statements should be referenced and should not be original research.
• English like 'Science has established- is rubbish. Scientists did; and the word 'is' is more concise.
• Headings must be understood by the general intelligent reader- so keep them simple annd to the point.
• Illustrations should be relevant. They should, where possible be geotagged. The caption should not be an article in its own right.
• Someone put Vitruvius in a footnote.
• The lead paragraphs should be a synopsis of the article and should not refer to concepts that are not explored in the article.

And apart from that it is good to see we have some new input. ClemRutter (talk) 14:46, 12 February 2008 (UTC)

and here's me looking for a rant when the points raised are fair. Of concern yet again is the amount and layout of the images. Does each form of sundial have its' own gallery. P.S. I thanked User talk:WillowW for the gif of Top view of an equatorial sundial; but you are correct in that labels shouldn't be a essay in themselves. Edmund Patrick ( ^confer _work) 15:00, 12 February 2008 (UTC)

Hi, and thank you for the welcome! :) I realize that everything I've added is not as it should be, but I'm just starting here, so please be patient with a relative newbie. I'll try to satisfy you all before I lay down my pen. My personal style is to add material, organize it and then reference it, once we've agreed upon what we'd like to say. I think you'll find, however, that everything I've added may be found in the books of the bibliography, some of which I added recently.

I agree that the history parts, especially Vitruvius, need more filling in and more organization, which I'll be happy to do once we've added the various types of sundials. I might add a bit today about the Lambert, capuchin and polar dials today, which are missing.

Oh, the parts of the lead that aren't yet covered? They will be, just please be patient with me! :) Willow (talk) 18:07, 12 February 2008 (UTC)

PS. I appreciate why you think that the anthropomorphism "Science has shown" is poor English. For me, however, the phrase "Scientists have shown" begs the question of which scientists? and I was wary of trying to track down the exact history by which scientists first established experimentally that the Earth rotated. It seems like a lot of work — but perhaps you have a good reference? I do not believe that Copernicus proved that that was so, although he argued that it was more plausible than assuming that the earth did not rotate. The agreement of astronomical observations with the Newtonian model of gravity is nice, but not definitive. I'm aware of Foucault's pendulum, but surely there was earlier experimental evidence? If you know what it is, I'd be most grateful. Willow (talk) 18:07, 12 February 2008 (UTC)

I see that we are in good hands. In the past we have suffered from 'the oh, I have a piccie of a sundial- I must post it onto the sundial page' mob. One of our expert contributers Carl Sabanski was arbitorily blocked and we fought months to get him whitelisted, and editors who would make a few major changes and disappear before we could work out whether it was damage or inspiration. At the moment I am working on a UK specific problem- conversion of Grid references in to GPS coordinates see River Teise and doing a javascript tool to aid the conversion; it fits in with the Geotagging project. This is keeping me fairly occupied. My sundial interests are to ensure that enough mathematics are included so the reader can reconstruct one, and that the page is not overwhelmed with extraneous or off task detail- which I recognise because that is what I do if left alone. Have fun, and when you are ready I will come in and discuss improvements here. ClemRutter (talk) 10:14, 13 February 2008 (UTC)

the new look sundials article

If I have read the above from Willow and Clem then instead of everybody editing in freefall the article should be allowed to develop. I must say upon 1st reading (and I always need at least 2) the article is informative and interesting. So I will not be bold yet but will say that the video of brookgreen gardens adds nothing IMHO so I will discuss its removal at some point in the future. Well done Willow, some lovely explanations. Edmund Patrick ( ^confer _work) 16:59, 13 February 2008 (UTC)

Looking a fresh at the article, I have profound misgivings.The article seems to refer to a 'Model of non heliocentric planetary universe, that is not supported by a reference. At most this should be of paragraph status. the term celestrial sphere doesn't make the index of Waugh.', though is used on Sabanski for the definition of celestial north pole, and is included in BSS glossary. It is a nice idea but we are here to report what has been published.

As I have said I find that there is too much prose which can be drastically reduced. Looking at other paragraphs they are littered with POVs using adjectives likr the 'oldest' the 'best' etc (some of which were probably in my early edits) that need to be zapped.

I still need to reintroduce some mathematics, as Carl Sabanski has been whitelisted there is a rich source there.

Brookgreen Gardens South Carolina is a sculpture park, and with only the evidence of their video it seems that this is not a mathematically correct dial, as there is coloured grass where the pads formally were suggesting they move them over the course of the year. I think it is interesting to see a video, but the sound track where the couple suggest that the dial is accurate to their watch is unhelpful to the article- possibly a paragraph on Pleasure generated by even pseudo dials. ClemRutter (talk) 10:15, 14 February 2008 (UTC)

Good morning, everyone! :)

The "oldest" and "best" bits may equally have come from me. I'm kind of enthusiastic, and if I'm editing quickly, I don't always catch my enthusiasms before they escape the barrier of my keyboard. ;)

I do agree that a bit more math might help, especially if we'd like to give enough information to the average reader so that they can build their own. I realize that Wikipedia is not a how-to manual, but I'm sympathetic to the wish, and if it happens naturally in the course of explaining the various sundials' principles, then great!

I couldn't make the video play, so I can't form an opinion about it as yet. As I mentioned above, I'm planning on making an animation for every type of sundial. Personally, I feel that we ought to condense the various subsections on re/de/inclining planar dials in which the style points along the celestial axis, and clarify what we mean by re/de/inclining, maybe with a schematic diagram or two? For the polar dial, I was thinking of making the direct vertical church-tower dials with the blue faces do double duty? You see that the Eastern face is a polar dial. I think the artile would also benefit from pictures of a polyhedral sundial and of a sundial in which the style is a sharp edge, e.g., a cylindrical cavity dial or a gravestone sundial in the form of a cross or Star of David or some such. What do you all think?

I think we might set our sights on making this article an Good Article and, ultimately, a Featured Article, what do you all think? I have several friends who are very good at copy-editing and clarifying explanations for lay-people, and who I'm sure would be willing to help once we thought we were ready. of course, that's a long way off, since all the referencing and whatnot has to happen before then.

Talk to you soon, Willow (talk) 10:58, 14 February 2008 (UTC)

Suggestions. In one article I worked on the lead paragraph got impossibly long. So we renamed it Introduction, and wrote a new lead properly structured lead paragraph. I think we could do that here. Then re-jig a couple of the next headings- making them subheadings etc. Celestial motion is a valid subparagraph of introduction but was off topic for dials.

Terminology needs to come before history and cleaned up-- but then I think that history should possibly lose prominence and drop down the running order. If we could show a progression from one type of Egyptian dial to a Greek dial to Roman to saxon to Gothic yes- but that is not our story.

I will not lose any sleep if the reclining dial in Recife bites the dust- there is a better one on Commons- but it doesn't definitively illustrate the recline.

ClemRutter (talk) 21:29, 14 February 2008 (UTC)

Hey Clem, those are good suggestions! :)

Since the article is likely to be longer than 50kb, I think we could have four paragraphs in the lead, but they needn't be bears impossible to understand. I'm thinking of making a terminology figure with labels to help illustrate the concepts; I'll use letters as labels so that the figure can be transferred to other Wikipediae. I agree that the History could drop down to hear the bottom, since it will probably make more sense to the reader after they've gotten the various principles. I found a cool archeological article this morning about a sundial that might be the fabled arachne. It was an equatorial dial that used only a nodus, instead of a style. The nodus was a horizontal bar on the top of the dial, and the hour lines were beautiful circles, just like a spiderweb. :) Willow (talk) 22:57, 14 February 2008 (UTC)

OK, so I have done a little. I didn't know about Jaipur- but have spent several hours on Google Earth wandering around and doing so Geotagging and then doing some corrections there. Patrick, where exactly is the dial at Houghton Hall so I can tag the location of the camera- it is 39 years since I was there and seem to remember it was in a stable block and not on the main hall. Kraków was less of a challenge. I am removing unnecessary formatting from each image as I now understand is best practice. Some users set their browsers to cope with their eyesight needs and specifying a px overrides this. Image captions do not need to be sentences, but in an article like this I think it is crucial that the location and lat/long is given. WillowW could you spend a little time adding inline references to all the new content- before a bot- starts complaining. My main source has always been Waugh, once referred, you only need to type <ref name="waugh"/> not a full citation the next time. I have put a link to a unwritten page for sundial mottoes- experience tells me, that with out it, this article will be submerged in contributions! ClemRutter (talk) 13:31, 17 February 2008 (UTC)

Thanks Clem, I'll start on that tomorrow; I'm rather swamped today with real-world things! :) Talk to you soon, Willow (talk) 14:19, 17 February 2008 (UTC)

[1]is a very good image of the Houghton Hall sundial cupola with all four faces. As it is on the net I assume we can use it, though I will check that out if necessary. It would explain the differences between the faces perfectly, but is three images. Any thoughts fellow editors? Clem, I will check with the guide book when I find it, I would have said Stables if anyone had asked but you know how it is as soon as someone does you question the original thought! Edmund Patrick ( ^confer _work) 17:13, 17 February 2008 (UTC)

Clem I have added to the motto list, as this is an opportunity to try to lay down some ground rules etc before it is (to quote) submerged in contributions! - what do you think. Edmund Patrick ( ^confer _work) 17:52, 17 February 2008 (UTC)

Houghton Hall.I would leave it at the moment- we have too much material already. I have the Restoration House dial that is similar (and geotagged) that is commented out. I will edit the banner diagram of declining dials- as there are some people out there die kunnen niets Nederlands spreken. —Preceding unsigned comment added by ClemRutter (talk • contribs) 18:32, 17 February 2008 (UTC)

Clem, Houghton Hall sundial: Google he say sundial tower at: 52.827469, 0.657616 not at the stables but the wing to the right of the main building. Edmund Patrick ( ^confer _work) 11:15, 18 February 2008 (UTC)

Not dead yet ;)

Hi all,

Just a little note that I haven't left! I'm working on making a few new illustrations, explaining the nomenclature and some old-fashioned dials. They should be done by early next week, please be patient! :) Willow (talk) 11:51, 23 February 2008 (UTC)

But I may be soon, I can't keep up. There are eight images of dials that have been added without the necessary lat/long details. It takes hours of Google-earthing to locate them and add the correct location tag to commons (of the camera) and coord tag to the (w) artifact. One illustrating a motto I suspect is a pseudodial (ie decorative and not accurate) but no metadata. Can we please post the metadata with the dial? ClemRutter (talk) 10:29, 26 February 2008 (UTC)

Sorry, sorry, sorry — I didn't realize how much work it was for you! I'll put a moratorium on new sundials for me, and try to geotag those that I added. I got the analemma at Ste. Marie-Madeleine church and I'll try to track down the Polish ones as well. Thanks very much for your help, Clem! :) Willow (talk) 12:43, 26 February 2008 (UTC)

OK, I added some more geotags. I can't be sure, but the motto sundials seems OK; its hour-lines all seem to pass (roughly) through the base of the gnomon, and the noon, 6am and 6pm hour-lines are perpendicular as expected. We'd need to measure the hour-line angles to estimate its designed latitude. Willow (talk) 16:24, 26 February 2008 (UTC)

Universal Ring Dial - not oriented to north???

In changing this article, the universal ring dial seems to have magically acquired the ability to determine the time without being oriented to north. If not oriented to north, the equinoctial ring is not equinoctial. The reason that the gnomon rotates is to permit the sun's light to pass through the hole directly rather than obliquely.

In addition, the claim that there are both simple slit and movable gnomon forms. Can someone provide a link or common reference to a simple slit type? I've never heard of such a thing.

If this is corrected, the dial would seem to be in the wrong section. --Michael Daly (talk) 20:24, 14 March 2008 (UTC)

Hi, I'm still away at my sister's helping with wedding preparations, but I'll try to answer your questions from memory, and then answer them more fully when I return to my books and library next week. I'll also fix up the North-South hemisphere thing then, unless someone else would like to do it beforehand. :)

Naturally, the gnomon of the universal ring dial must be oriented along the celestial axis, we agree on that. Since the user is assumed to know her latitude, she needs only to find the direction of true North. The pivotal question is whether she needs an external method for determining true North. As I understand my references and the dial, she does not, by the following argument. Setting the perforated slider at the correct date and requiring the Sun's ray to fall on the equatorial ring is equivalent to requiring that the Sun have a specific altitude angle relative to the plane of the equatorial ring. If the gnomon is aligned with the celestial axis, this corresponds to requiring that the Sun have the correct declination on the celestial sphere for the given date. If the gnomon is not aligned with the celestial axis, the angle between the Sun's ray and the plane of the equatorial ring will not (in general) equal the value required by the perforated slider. If I'm imagining it correctly, only two orientations of the ring will satisfy the angle constraint, corresponding to the two intersections of two circles on the celestial sphere. The two circles are (1) the circle centered on the position of the Sun, with radius equal to its co-declination (the angle between the Sun's position and the celestial north pole), and (2) the circle centered on the vertical axis at that local latitude, with radius equal to the co-latitude (the angle between the vertical vector and the celestial north pole). Ideally, the user should be able to eliminate one of the two orientations as implausible (say, by rough time since sunrise, a compass, or somesuch method) and, thus, she should be able to determine true North as the one plausible orientation of the ring in which the shaft of light falls on the equatorial ring (provided that the latitude is set correctly). Do you agree with my reasoning? I can make a geometric figure illustrating the principle; maybe that would be helpful for the article?

I saw the simpler slit-type ring dial (micro-armillary sphere) in a book, which I'll try to find when I get home again. If I can't dig it up, I'll happily remove the reference to it. Thanks for being patient with me! :) Willow (talk) 22:49, 14 March 2008 (UTC)

I did the calculation last night, and the two orientations that satisfy the angle constraint give times that are equally spaced about noon, e.g., 9am and 3pm. Hence, true North and the correct time can be determined if you know whether it's before or after noon, similar to altitude sundials. Should I add a Figure showing that? It requires only basic spherical trigonometry, but maybe that's too much detail for this article? Perhaps we should start a separate article on the universal ring dial instead? Willow (talk) 14:41, 17 March 2008 (UTC)

I looked into my own books and found a few examples of what I meant by a "simple" universal dial. Plates 31, 39 and a few others in the Rohr book (see Bibliography) show portable brass pocket ring dials that function as an equatorial dial or armillary sphere, in which the angle of the ring (upon which the time is read) relative to horizontal can be set at various latitudes. The gnomon can be a slit (Plate 39, if I'm reading it correctly) or a pin (Plate 31). Perhaps that's not what everyone means by a "universal" ring dial, however; I took "universal" to mean "can be set to different latitudes. Willow (talk) 14:07, 21 March 2008 (UTC)

Ok - on re-reading the section after reading your explanation, I understand the meaning better. I guess the text could be tweaked a bit to show how the technique you describe will result in the dial aligning itself with north. As it stands, my comments above are wrong.

I can't get my hands on the Rohr book easily (it's in a library about 30km away...), so I can't check the info. I should note that the term universal equinoctial ring dial refers to a specific instrument. If the instrument referred to in Rohr is not this form, it is likely a different instrument and shouldn't be lumped in with the universal equinoctial ring dial type but rather a similar type of ring dial. The universal type shown in the image in this article is identified with a sliding gnomon design in all the references I have. --Michael Daly (talk) 18:54, 21 March 2008 (UTC)

I might be mis-naming them. If I recall correctly, they're often called "pocket equatorial dials" (e.g., the pin-gnomon dials in Plate 31 of Rohr) and I assumed that they could be considered as "universal" because the equatorial ring can be set to a wide range of latitudes. (For me, "equatorial" means the same thing as "equinoctial".) But those "simple" universal ring dials might have some other "official" name among the cognoscenti of sundials. Let's try to find out! :) Willow (talk) 19:10, 21 March 2008 (UTC)