Talk:Sundial Bridge at Turtle Bay

Frosted glass
From the Article "The deck is surfaced with transparent structural glass, with a view of the water below as one crosses."

This is actually incorrect: The Bridge was planned with this in mind, but (at least this is the explanation printed in the newspaper) the clear panels and view of the river below disoriented people so much that the panels were frosted and are now translucent (this shows in the photos btw).


 * Stupidly enough, we'd actually need a source for this if we were to change it24.205.34.217 00:53, 26 April 2007 (UTC)

Request for explanation
Could someone explain me the funktion of the bridge as a sundial? I am expert in these things, and I don't know a sundial, which works correct only at one day in the year. The best would be, to give me pictures from the scaled plane and the "gnomon" (is it only the shadow of the top point which gives the information?). 62.204.120.21 (talk) 13:55, 29 July 2008 (UTC) Analemma (a german user)


 * When I saw it two months after the solstice, the dial was crossed by the shadow of the gnomon a little way below the point: see this photo, which I took from the dial. At the solstice, the sun would be higher but I think not enough for the shadow of the point itself to lie on the dial, I'm not sure. It was still quite accurate at that time (within a minute or two), but my guess at the reason it's not perfect year-round is that the angle of the gnomon is not sufficiently tilted: it's 42 degrees from vertical, whereas to match Redding's latitude perfectly an angle of 49.5 degrees would be needed. —David Eppstein (talk) 20:19, 15 August 2009 (UTC)
 * Actually, the latitude of this bridge is 40.5 degrees, not 49.5. The source of the 42 degrees is an Architectural Digest article no longer available, cannot verify this or the article's source. Jaguarmountain (talk) 19:43, 9 October 2022 (UTC)

Sundial or not?
Every object and natural feature on the surface of the Earth provides the hour with exact precision one day (the solstices) or two days (all the rest of the days) every year, and that is not reason enough, properly speaking, to say that everything bathed by the sun is a sundial. In that case, any tall building has all its corners acting as gnomons, and the largest sundial on earth would be the mountain rising higher over its surroundings. Sundial bridge is a beatiful example of a bridge, with some solar effects, but it is not a sundial, not because the author did not know how to do it, but because he did not intend to. We can not misinform people. For the Sundial Bridge to be a true sundial, the gnomon should be alineated with the Earth's axis, and it is not. —Preceding unsigned comment added by 83.61.157.84 (talk) 22:05, 12 December 2009 (UTC)


 * This particular object is named a sundial, was designed to be a sundial, and features a dial display. It is also, per the discussion below, accurate months away from the solstice. I see no justification for removing the sourced claim that it is the world's largest sundial and replacing that with an unsourced opinion that it is not really a sundial because it fails to meet some imaginary standard that is not applied to other sundials (the gnomon being precisely aligned to the latitude — note that most garden sundials are similarly misaligned). I'm reverting again. —David Eppstein (talk) 22:19, 12 December 2009 (UTC)

That the bridge is not a sundial is not an unsourced opinion. You can consult the American Sundial Society, the British Sundial Society, the German or Japanese ones or any other authorized source. All professional associations over the world devoted to design and construct sundials have their manuals and codes, that collect ancient and modern knowledge. The Sundial Bridge does not meet the mandatory design rules universally used to assess if an object is to be considered a sundial nowdays. If people buy artifacts for their gardens that have been designed and manufactured without any technical backup or have been correctly built as real sundials for a given latitude and they place them in distant locations, they are no longer sundials or at least they do not work as such. It is also very important to note that the main factor affecting precision of a sundial is size, so therefore it would not be acceptable at all that the largest sundial (Sundial Bridge), having been erected recently and with all the vanguard techniques avalaible, had no precision at all. Finally, but not less important, trying to asign to Sundial bridge the title of largest sundial on the planet, despises the painstaking and honest work of those artists, engineers, associations, cultures and civilizations that have devoted huge efforts to build large and precise sundials that are simply that: sundials. Their achivements and goals would vanish if any architectural icon with a resemblance of a sundial would be included into the gnomonical class. Calatrava, as civil engineer has never tried to cheat people and refers to his bridge as a sundial in the poetical sense (linked with the dance of lights and shadows), but never in the technical sense because he knows perfectly well it not a sundial. For the shake of rigour you should re-write this aspect of your article. It is not an attack to your work, it is a piece of advice contributed by a group of professionals of sundials making, some with more than 28 years of professional activity, to which I belong. —Preceding unsigned comment added by 83.61.157.84 (talk) 23:21, 12 December 2009 (UTC)


 * No. You need a source stating that this particular object is not really a sundial; anything else is original research by synthesis. And if you find such a source, you still don't get to rip out the sourced claims that it's a sundial and substitute them by the opposite: what WP:NPOV demands in that case is that you report both sides of the controversy. —David Eppstein (talk) 23:35, 12 December 2009 (UTC)

I believe that you have written a totally unfunded statement about the bridge and it is your report that lacks entirely of any valid scientifical source. You seem not to be open to consultations to scientific knowledge about sun astronomy and dials. You will not find any sicientific or sundial association backing your claims. I see below that this article of the wikipedia had the same claim before from a german specialist. You are fabricating the information, and thus misinforming people, and it is against the aim of wikipedia or any encyclopedia. In any case if you would like to classify Sundial Bridge as a one day sundial, (perfectly possible anyway) it would not be the largest. You have the obligation to investigate before writting whatever you want or just repeat false information. Mount St. Michel, in Normandy, France, has been called Le Mont Solaire (Sun Mountain,very much like the Sun-dial-bridge) and reported as the largest sundial on earth on the same basis than your claim. You can find many videos and texts like this doing a small search: "This past September the French army installed 600 one meter square reflective panels in the shape of Roman numerals on the sands of Mont Saint-Michel, a small rocky island off the coast of Normandy. The island’s 150-foot abbey spire cast a shadow three quarters of a mile long that swept across the numerals, making the timekeeper the largest sundial ever constructed, beating out Jaipur, India’s Samrat Yantra". Compared to Mount Saint Michel, Sundial Bridge looks like a walking stick. But there are many more examples, perfectly documented that you have failed to study. For example a real sundial much larger than Sundial Bridge, already completed in France is Castillon Barrage. You are obliged to make a search on your own, see the videos, pictures and plans, or travel there, to learn. Here you have an excerpt from Real Science: "2009 is the Year of Astronomy, 400 years after the first observations with a telescope by famed astronomer Galileo. To mark the occasion, French engineers and scientists are converting a giant dam in the Provence region of southern France into what they say will be the biggest sundial in the world. Refacing the dam costs about $200,000 Euros and is expected to draw thousands of tourists who flock to the region to visit the nearby Verdon canyons". You are wrong when you fail to admit the facts and transmit others the burden of demonstrating that your statements are not true and have no scientifical base at all. —Preceding unsigned comment added by 83.38.254.170 (talk) 08:50, 13 December 2009 (UTC)


 * You are arguing as if this is a matter of opinion and that you need to convince me that my opinion is wrong. That is an invalid basis for editing on Wikipedia. We need to go by what the sources say even if we disagree with what they say. We have reliable sources that say that it is a sundial. They may themselves be incorrect, but that is what they say and that is what we have to report. If you provide sources contradicting them, then we can at least report on the contradiction, but so far all you have done is argue and that is completely unproductive. See WP:Truth. —David Eppstein (talk) 16:06, 13 December 2009 (UTC)

You have not produced a single piece of verifiable evidence of your claim, and that has to be the root principle of the information provided by wilipedia. I have given information -for instance- about the Castillon Barrage, that is far larger as a sundial and that has been reported by scientific european associations that you can reach, unless the case that you do not want to because for any hiden reason you want to maintain false information on the wikipedia. I have provided more than enough reliable information that demonstrates that Sundial Bridge is not a sundial itself and that in any case it would not be the largest. I have also provided enough resources for anyone interested in studying and research the scientific evidence that supports what I have explained. Here there are a few more pieces that will help approach the issue from a scientific perspective, free from personal passions and beliefs and unfunded data like general journalism articles, that are not a verifiable source of information and therefore invalid to support your claim. A) The Sundial Bridge cannot be found in any sundial catalogue of any sundial society. B) If a proposal in that sense was sent to the North American Sundial Association it would be rejected for sure. C) Anyone can buy a book or read one on the internet about sundial design and making and after a few paragraphs realizes that Sundial Bridge is not a sundial. D). The textbooks taught in Architectural and Civil Engineering university education, state that objects like Sundial Bridge are not sundials. E) One of the best sundial designers and makers that has produced some of the best sundials ever, northamerican John Carmichael, relevant member of NASS and BSS, has a project to convert a solar observatory at Kitt Peak, that would become one of the largest sundials of the planet, and the largest of North America, only second to the Castillon Barrage in France. Anyone can contact him through his webpage  F). The Sundial bridge is in USA, where the design criteria and guidance for bridge projects, would not allow for this case an angle misalignement for the cantilever higher than 0,26 degrees, so the bridge is far away from being a sundial, because the cantilever is not within that range of the polar axis, but far from it. Therefore, for the sake of scientific knowledge and the divulgative effort of wikipedia, it is the duty of all of us to reflect the real facts in the articles. And it is time that wikipedia takes part to avoid more manipulations. —Preceding unsigned comment added by 83.53.133.173 (talk) 16:21, 13 December 2009 (UTC)


 * Lack of evidence is not evidence of absence. But if you can find a sourced claim that some other specific object is the world's largest sundial then we can at least say something like "the sundial bridge has been claimed to be the world's largest sundial, however, X is larger." PS since I've run into the limit on how many times I can revert, and in any case since this repeated edit and revert cycle is highly unconstructive, I've asked on WP:Content noticeboard for a third opinion. —David Eppstein (talk) 16:21, 13 December 2009 (UTC)


 * Taipei 101 is taller, and is a sort of unsatisfactory vertical sundial with a relatively small dial plate in Millennium Park which can be used only in the afternoon. Binksternet (talk) 18:09, 13 December 2009 (UTC)


 * The North American Sundial Society lists the Calatrava Sundial Bridge in its links on the web. They define gnomon as being either polar-pointing, horizontal or vertical. They do not define style as a polar-pointing gnomon in the way it was used after the late 16th century—instead they define style as the line in space which is used to indicate time on the dial plate. Binksternet (talk) 18:34, 13 December 2009 (UTC)


 * In 2005, Dr. David P. Stern was asked whether the Calatrava Sundial Bridge is a sundial, and he said that it would be an accurate sundial if the center of the dial plate were located in a spot where a line from the top of the bridge pylon met the ground at an angle of 40.6°. Stern said he did not know if this was the case. Binksternet (talk) 18:41, 13 December 2009 (UTC)