Talk:Compass

degrees

Shouldn't this article mention that customarily 0° is aligned with north and that the other three primary directions are at 90°, 180°, and 270°? —optikos 21:23 22 December 2005

Heavily Edited some portions, added a section + picture on Han dynasty Spoon compass

Added these portions: "=Han Dynasty Spoon Compass (200 BCE - 200 CE)=

• "Earliest records show a spoon shaped compass made of lodestone or magnetite ore, referred to as a "South-pointer" dating back to sometime during the Han Dynasty (2nd century BCE to 2nd century CE). The spoon-shaped instrument was placed on a cast bronze plate called a "heaven-plate" or diviner's board that had the eight trigrams (Pa Gua) of the I Ching, as well as the 24 directions (based on the constellations), and the 28 lunar mansions (based on the constellations dividing the Equator) . Often, the Big Dipper (Great Bear) was drawn within the center disc. The square symbolized earth and the circular disc symbolized heaven. Upon these were inscribed the azimuthal points relating to the constellations. Its primary use was that of geomancy (prognostication) to determine the best location and time for such things as burials. In a culture that placed extreme importance on reverence for ancestors, this remained an important tool well into the 19th century. Even in modern times there are those who use this divination concepts of Feng Shui (literally, of wind and water) for locating buildings or fortuitous times and locations for almost any enterprise. There is a story that the first Chin emperor used the divining board and compass in court to affirm his right to the throne. Primarily, the compass was used for geomancy for a long time before it was used for navigation"

Silverman, Susan. AC. http://www.smith.edu/hsc/museum/ancient_inventions/compass2.html"

I have sited my source as Susuan Silverman from the educational website "smith.edu."

Intranetusa 22:05, 10 May 2007 (EST)

Are all compasses magnetic?

See Ralph Bagnold -Fiber]] Any sundial will act as a compass won't it?

My question is whether a lodestone and a compass are the same things. In Gulliver's Travels a lodestone was used to direct the floating island. You can't just say it was a compass. -Adrian

• Lodestone was historically used for compasses—it's a natural magnetic substance. Only later were other magnets discovered. --Simetrical 22:23, 3 Jan 2005 (UTC)

there are gyrocompasses which use electromagnetism in functioning, yet not the same way as the traditional compass.

some compasses are neither magnetic or sundials, but solid state 'gyrocompasses' i was actually looking for an explanation of how they worked which lead me here, i couldnt find anything on wikipedia about solid state compasses or fiber optic gyrocompasses, i think someone should add this, i am intensely curious

Sundials are not compasses. Compasses point to only 1 direction. The sundial moves according to the position of the sun. The sundial is an early form of the clock. -intranetusa

I read in Scandinavian Science Illustrated that the Vikings used primitive compasses based on the sundial principle. They needed adjustment to remain accurate for more than three weeks, but apparently they worked fine other than that. They were more advanced than sundials in several ways. More info [here]. --Safe-Keeper 04:09, 31 July 2007 (UTC)

Soundings

Prior to the introduction of the compass, wayfinding at sea was primarily done via celestial navigation, supplemented in some places by the use of soundings.

What kind of "soundings" are referred to in the article? None of the soundings listed in Wikipedia seem to be \DANIELLA ENVENTED COMPASSES O.K. bed could also be used as a means of navigation, but I don't know when this was first used. Billlion 22:59, 3 Jan 2005 (UTC)

Who picked up compasses from whom?

As of a week or two ago, the beginning of "History of the navigational compass" (written by Loren Rosen) read:

Knowledge of the compass moved overland to Europe sometime later in the 12th century. Arab mariners apparently learned of it from the Europeans, adopting its use in the first half of the 13th century.

Anonymous user 130.209.6.40 changed this to read:

Knowledge of the compass moved overland to through the Arab countries and then to Europe sometime later in the 12th century.

Which one is correct? —Simetrical 05:06, 30 Jan 2005 (UTC)

Well I have found different opinions but this article [1] states

 By the 10th century, the idea had been brought to Europe, probably from China, by Arab traders.

but we could do with a more respectable historical reference! Billlion 05:55, 31 May 2005 (UTC)

According to the Dictionary of the Middle Ages Volume 3 page 506, the compass was invented in Italy:

"The magnetic compass has been known and used in the Western world since the twelfth century. It is believed to have been invented in the Mediterranean region, probably at the Italian port of Amalfi, which was engaged in shipping magnetic ores from the mines of Elba."

MY 2c... Remove the history. The compass is likely one of those devices invented everywhere are the same time. Even the best research on this would likely be on shakey ground anyways. - Ravedave 03:40, 26 August 2005 (UTC)

I suspect it is a contensious, depending who you talk too. It might be good to frame it as such and list the various theories, rather than declare definitive knowledge. Stbalbach 03:54, 26 August 2005 (UTC)

Real apologies for this. I suspect it may have been me who changed the sentence (about the Arabs and the Europeans) although frankly it was a long time ago and I can't remember. In any case: the source I may (or may not) have used is as follows: 'The mariner's compass [...] was [first] deployed in Chinese ships around 1090....this was....the culmination of a series of Chinese innovations that stemmed back to 83 BC when crude compasses were invented, and even as far back as the Fourth Century BC, when .... 'lodestone' compasses were discovered. The Italians merely borrowed the compass, which had diffused across to ...Europe via the Muslims, from the Chinese.' (The Eastern Origins of Western Civilisation, J. Hobson, Cambridge University Press, 2004). The source given is: 'Hourani, G. Arab Seafaring in the Indian Ocean in Ancient and Early Medieval Times (Beirut, Khatats, 1963) pp108-109.. ISBN 0691000328 130.209.6.40 16:59, 20 February 2006 (UTC)

---

There is no evidence that the Italians were the first Europeans to use a compass. The first European to mention a compass was an Englishman, and since he did not mention specify an specific location for the sailors, the assumption be that he was talking about local sailors, i.e., English sailors. Had it been Italian or other foreign sailors, he would have mentioned the fact in his description.

Also The only supporting data for assuming that the Europeans learned the idea of the compass from the Chinese or Arabs is that use of the compass for navigation was first mentioned in writing little before the European. All other evidence points toward an independent invention. It is first mentioned by a northern European, not a southern European (i.e. Italian) or Arab who would have had the most direct contact with Chinese sources. And the European compass is always potrayed as pointing North, not South as in Chinese compasses. The closeness in time between European and Chinese sources can be explained that the 11th century seems about the time when steel needles became available in Europe. Before steel needles, it would have been hard to make practical compasses. Regular iron needles would loose their magnetism too quickly to be practical (iron do not retain magnetism as well as steel), and making the needles out of natural loadstone runs the risk of ruining the natural magnetism of the material. If you heat iron past its Curie point while making it into a needle, it will loose it magnetism. Using a fish or turtle shaped piece does not make a very practical compass for use on ships. The Ancient Romans and Greeks did not use steel needles, so evein if they were aware of the directional property of loadstone, they would not have found it practical to make compasses. —Preceding unsigned comment added by 66.51.147.97 (talk) 01:34, 17 December 2009 (UTC)

Lensatic?

I've been shopping for a compass, and many are described as "lensatic compasses" -- in particular, all military compasses I've found. What is a "lensatic" compass? This should be added to the article.

A lensatic compass has a lense (typically in the sight) so that when held to the eye to take a bearing you can read the dial. This is typically a military style field compass. If you get one maybe you could take a phot of it for the article. Billlion 05:45, 31 May 2005 (UTC)

Compass usage section

The section about using compass contains two images that are important part of the explanation. Any literature material on this topic has these two illustrations in one or another form and is not understandable without them. Please do not remove, these are not just images of the compass. Audriusa 09:40, 13 September 2006 (UTC)ffrrfr

Compass spoon

Oh my. At the risk of making a fool of myself: is there any chance that the line "[i]n China it seems that the convention was that the compass spoon (they used a spoon instead of a needle)", taken from History of the navigational compass, is not a vandalism? If it is, don't bother mocking me, just fix it. — Itai (talk) 23:38, 25 November 2006 (UTC)

accuracy of article

Since the Chinese used the compass in navigation, they had a practical mariner's compass. It may be possible to figure out the relative quality of early compasses, but I'm not able to do it.

The modern mariner's compass, as discussed in detail in the article, is not a compass needle in a dry box, but rather one that uses fluid to support the needle. I've adjusted the article. I specifically disagree with Ma's statement at the head of this page. The use of "true" in this sense is really ethnocentric. It's a loaded word, to be used only when there is no possibility of confusion. DGG 04:54, 27 November 2006 (UTC)

+++++++++++++++++ The above statement is not necessarily correct - simply becaused they used the compass in navigatoin, does not mean they had a practical mariner's compass. The term "mariner's compass" means a lot more than just a north pointing device. A mariner's compass does more than just point north - it also allows you to take specific bearings, and steer a specific course. A magnetic spoon spinning around on a plate may tell you the general direction of north, but it would not be practical for steering a specific course heading on a pitching boat.

The evidence is that the Chinese did not have a PRACTICAL mariner's compass. The only written evidence I have seen makes it clear that the compass was not a primary navigation tool for the Chinese, but only an aid used when other sources of navigation were not available (Phing-Chou Kho "in dark weather they look at the south-pointing needle"), and there is no evidence that Chinese navigation maps and charts had compass bearing directions on them. Nor do we find any evidence for a revolution in Chinese sailing practices as a result of the compass. This in direct contrast to the West, where the sailing practices thousands of years old in the Mediterranean Sea underwent a dramatic change at the time the mariner's compass was developed, and where portlan charts given specific sailing directions based on magnetic compass bearings. The mariner's compass was used as a primary navigation means in all weather, and not just when other sources were not available. Taking a compass reading on pitching and rolling deck on board ship with a needle floating in a bowl of water would not be practical. The dry pivot mounting of the needle used by European compasses would be less suspectible to the rolling and pitching of a ship, and the mounting of the compasses in a gimbal box, which the Chinese lacked, would make the compass even more practical. —Preceding unsigned comment added by 66.51.147.97 (talk) 20:11, 18 December 2009 (UTC)

The true mariner's compass

The term is not uncommon and can be also found in scientific literature, for example: Barbara M. Kreutz, "Mediterranean Contributions to the Medieval Mariner's Compass," Technology and Culture, Vol. 14, No. 3 (Jul., 1973), pp. 367-383. This justifies its use as opposed to the more colloquial "familar mariner's compass". Regards Gun Powder Ma 04:51, 27 November 2006 (UTC)

Ma, do not revert without discussing. You are here dealing with a technical subject, and it would be well for you --and me--to wait for comment.I have no intention getting into a revert war with you or anyone, here or elsewhere--though possibly some WP people would be tempted by this particular revert. But consider the word "true" in "true north" in this article--it has a meaning. How about true early European. It is undoubtedly true of early European compasses, just as it is false for current ones. DGG 05:11, 27 November 2006 (UTC)

True, dry or familiar compass are all accepted technical descriptions, as long as they fit the context, and one is not excluded on ideological grounds. That's why I say ok to your insertion in the entry (familiar), while I changed it in the text below to true again. "True" means in this context with a pivoting needle and a compass board which moves while the needle remains static in case the ship switches course. This "true" feature also remains with the late liquid compass. Gun Powder Ma 05:22, 27 November 2006 (UTC)

The supposed Olmec invention

I was unable to find the quoted article in the database of Revista mexicana de Fisica: http://www.ejournal.unam.mx/revmexfis/revmexfis_index.html

A.P. Guimaräes (2004) "Mexico and the early history of magnetism", in Revista mexicana de Fisica, v 50 (1), June 2004, p 51-53

Therefore, I cut the whole part out.

Good edit

Whoever mostly trashed my discussion of the US military dry compass; thanks! You know your stuff! But I carried a mini liquid-filled compass for some years, and the wear rendered it useless, so I did put back one sentence on that subject. Somebody might be trying to figure out what compass to carry for years; you never know. I politely refrained from suggesting outright that a dry compass with a needle lock might survive that treatment if water didn't get into it, which seems logical, and anyway, I don't personally know what treatment a really good liquid-filled compass will tolerate.

72.72.37.51 06:21, 7 January 2007 (UTC)Packer

Joseph Needham/Four Great Inventions of Ancient China

The change I made was:

• Joseph Needham attributes the invention of the compass to China in Four Great Inventions of Ancient China, but since there has been disagreement as to when the compass was introduced for the first time, it may be appropriate to list some important Chinese literary references leading up to its invention in chronological order:

From:

• Due to the place of its first appearance, most scholars credit the invention of the compass to China. Since there has been frequently confusion as to when a compass was introduced for the first time, it may be appropriate to list the important events leading up to its invention in chronological order:

The previous editor had deleted this line:

• It's included in Four Great Inventions of Ancient China (Si da fa ming) in one way or another.

This deletion makes sense as the information was redundant to the first line. ('inventions' pointed to 'list of chinese inventions' which itself points to 'four great inventions of ancient China.') Plus the line 'included' 'in one way or another' just isn't very specific. Add to that the vagary of 'most scholars credit the invention' and it just doesn't sound informative in a definite way. With the new edit there is a scholar listed by name along with his work that specifically credits the creation of the compass to China. Readers can then make there own inferences after reading all these articles as to whether they think the compass belongs to China or some other country. Aspenocean 09:51, 12 May 2007 (UTC)

"Readers can then make there own inferences after reading all these articles as to whether they think the compass belongs to China or some other country."

What? The compass was invented first in China, and then invented separately in Europe (where it was gradually improved). Period. End of story. Nothing more to discuss or "infer". Whether or not we can sit here and debate its diffusion from China to Europe is very trivial, considering how we have no evidence of its transfer (if it actually occurred in the first place), and quite possibly never will have such evidence. You have heard of common phenomena, haven't you?--PericlesofAthens 19:28, 16 May 2007 (UTC)

• You have heard of scholarly debate haven't you? If you were there at the time or otherwise have rock solid proof of the origins of the compass, the scientific community needs to hear from you right away. Aspenocean 20:31, 16 May 2007 (UTC)

Sure thing, bro! Just let me jump into my time machine really quick (lol). Following that brand of logic, I could also doubt if Alexander Neckham was truly describing the compass needle as well, about a hundred years later than Shen Kuo. Seriously though, this is a trivial pursuit. What evidence we have for the early compass in China is stated in the article, and valid for that matter.--PericlesofAthens 20:21, 19 May 2007 (UTC)

• In a recent edit the work of Joseph Needham attributiing the compass to China -Four Great Inventions of Ancient China- was removed and referred to as "plastering." I don't think the way to deal with controversy is to hide information. If you're going to bring up a controversial subject it should be lead in with a notable work by a notable author and that is why it is included here. Again, when there is controversy the reader can use information to make up their own mind. Aspenocean 03:14, 21 May 2007 (UTC)

And the controversey is what again? Yeah, Needham attributed the first discovery (or at least the first written reference) of the magnetic needle compass to Shen Kuo's Dream Pool Essays. The book isn't some big secret or conspiracy. When Shen Kuo was writing in the 11th century, he wasn't doing so to impress you and I, he was doing so to improve the knowledge of the known sciences in his day. You can argue all you want with Shen Kuo, the original source (and Needham for that matter), but I'm afraid you'll need a seance to do that. I wouldn't trust those spirit mediums though if I were you; instead I would just refer to historical texts.--PericlesofAthens 07:48, 22 May 2007 (UTC)

• My point exactly. I don't know what the problem is honestly. It was Gun Powder Ma that keeps trying to remove the reference to Four Great Inventions of Ancient China. I gather you've had conversations with this user in the past. This same user has in other edits removed referenced facts and more or less claimed he didn't like the reference because of its age. I hadn't intended on naming names, making accusations, or getting in the middle of anyone else's argument here; but was willing to assume good faith and believe there were editors who think there is a controversy. I do have an opinion of what's happening when an editor hides or obscures facts, but it has been discussed to death in other forums, and I dislike making too many assumptions. There are scholars who attribute the compass to China, and Four Great Inventions of Ancient China is a work by Needham. Just a plain fact and no reason to hide it away. Aspenocean 17:47, 22 May 2007 (UTC)

Ah yes, him and I are acquaintences from a history forum a while back (which I really don't visit anymore). He's a smart guy, with an honest and admirable interest in Western history, but when it comes to Chinese history he gets easily insulted by the notion that they could have done anything before a European had (which is unneccessary considering that the basis for the majority of global modern science, technology, mathematics, and politics comes from the European model, not Chinese). It's sort of upsetting and redundant to watch, especially in his misplaced loathing and distrust of anything labeled "Needham", even though Needham went to great lengths in his many books to accurately portray China in every field of study and statecraft. To say Needham's work is not credible is a challenge to his work that has to have some sort of grounds or evidence to show Needham was a 'fluke'. Besides questionable transfusion of technologies across the Eurasian world in the medieval period (which is hard to prove in the first place, and Needham never asserted he had direct evidence to show they had), the scientific community at large has nothing to refute in Needham's work. I don't care if the man wrote his books in the 50s, the 60s, or just last year, Needham is above and beyond a credible source.--PericlesofAthens 04:19, 23 May 2007 (UTC)

Updated Info, and one slightly disappointed Wikipedian

I made some new additions about China, the thermo-remanence compass, and the dry suspension compass.--PericlesofAthens 21:56, 27 May 2007 (UTC)

I also find it rather curious and questionable that someone would use Li Shu-hua's publication of 1954, in order to show that the method is still unknown of how the fish compass of 1044 AD would have worked. Clearly, someone was ignoring (unknowingly or intentionally) Wang Chenduo's work and Needham's publication made in 1962, which proved the Chinese used the weakly-magnetized thermo-remanence compass (which would have been inefficient, yes, but a compass needle nonetheless). It is also curious and questionable that no one mentioned the use of the Chinese dry suspension compass as early as the 12th century, and blatantly wrote that the only compass known in China before European influence was the wet compass placed in a bowl of water. To this I say: hogwash.--PericlesofAthens 22:15, 27 May 2007 (UTC)

Recent Reverts to the Thermo-remanence and Dry-needle compass

I have recently reverted the edits by Gun Powder Ma, who asserts that the existing sources contradict Needham's Volume 4 Part 1 of his Science and Civilization in China series, although I can't seem to find which contradictory source that would be. Gun Powder Ma, please point these sources out, as I do not think they exist.--PericlesofAthens 01:18, 29 May 2007 (UTC)

If Gun Powder Ma has a source (later than 1962) that contradicts this passage of the Wujing Zongyao (written in 1044 AD) featured in Needham's Volume 4, Part 1, then I would truly be astounded; here is the full excerpt from Needham's page:

"Actually, Khou Tsung-Shih was far from being the first to describe the water, or floating, compass. Until Wang Chenduo noted it, everyone had overlooked a passage in the great compendium of military technology, the Wu Ching Tsung Yao, edited by Tseng Kung-Liang and finished in 1044. Here the writer says:

When troops encountered gloomy weather or dark nights, and the directions of space could not be distinguished, they let an old horse go on before to lead them, or else they made use of the south-pointing carriage, or the south-pointing fish (chih nan yü) to identify the directions. Now the carriage method has not been handed down, but in the fish method a thin leaf of iron is cut into the shape of a fish two inches long and half an inch broad, having a pointed head and tail. This is then heated in a charcoal fire, and when it has become thoroughly red-hot, it is taken out by the head with iron tongs and placed so that its tail points due north. In this position it is quenched with water in a basin, so that its tail is submerged for several tenths of an inch. It is then kept in a tightly closed box. To use it, a small bowl filled with water is set up in a windless place, and the fish is laid as flat as possible upon the water-surface so that it floats, whereupon its head will point south.

Needham, Volume 4, Part 1, Page 252, illustration on 253.--PericlesofAthens 01:29, 29 May 2007 (UTC)

In fact, to contradict this, Gun Powder Ma would have to find a source later than 1995, since it was accepted by the scholarly community even by the time of Nathan Sivin's book Science in Ancient China, written in 1995, the part on the thermoremanence compass found on page 21 of section III.--PericlesofAthens 01:31, 29 May 2007 (UTC)

Furthermore, I would like to see the entire 373rd page of Barbara M. Kreutz's book Mediterranean Contributions to the Medieval Mariner's Compass,” Technology and Culture, Vol. 14, No. 3., in order to come to the conclusion if someone had not used her page as a means to post false information or omitting part of her writing to twist her intent. I say this because Needham, in 1962, quotes the passage of the Shi Lin Guang Ji (compiled in 1325 from material dating back to the 12th century), which says:

They also cut a piece of wood into the shape of a turtle, and arrange it in the same way as before (the south pointing fish), only that the needle is fixed at the tail end. A bamboo pin about as thick as the end of a chopstick is set up on a small board, and sustains the turtle by the concave under-surface of its body, where there is a small hole. Then when the turtle is rotated, it will always point to the north, which must be due to the needle at the tail.

Needham, Volume 4, Part 1, Page 255. Clearly, this is a dry suspension compass, it has nothing to do with water in bowls, and in craft is very different from dry European compass cards in box frames and with pivoting needles. More info from page 290 coming up...--PericlesofAthens 01:39, 29 May 2007 (UTC)

From the same volume, on pages 290 to 291, it shows illustrations of the suspension needle compass printed in Wang Zhenduo's book, and describes their use in China all the way up to the 18th century, despite the 16th century Italian compass-card being spread all over East Asia accompanied by the dry pivot. Needham also notes that dry suspension compasses were not as widespread in China as the floating type (both for navigation and popular in geomancy), but this does not mean it did not exist. I am guessing Barbara M. Kreutz's book (of 1973) notes that either

• the Chinese had the floating needle compass, and failed to mention the dry needle compass
• that since the dry suspension compass in China was not nearly as prominent or widely used as the wet floating bowl compass, mentioning the dry suspension compass wasn't worth mentioning in light of the European model of the dry box frame compass-card which prevailed
• or she made a terrible mistake at saying the only compass known in China was the wet one (I find stupid mistakes about China in tons of books, for example, refer to John Norris' book Early Gunpowder Artillery: 1300-1600, published 2003, which states that Wu Jing Zong Yao was a person who wrote a military treatise in 1044! Hah). I think I will be ordering her book soon, or see if it is available at my local library.--PericlesofAthens 01:53, 29 May 2007 (UTC)

With the evolution of the dry suspension compass in China (not the European dry compass-card type invented in the 14th century, and supposedly by one Flavio Gioja in Amalfi, Italy, around the year 1300 AD according to tradition, this date being asserted by historian Sylvanus Thompson, as Needham notes), by the 18th century the Chinese dry suspension compass used the following components (with illustration, as noted in Wang Zhenduo's work):

• a flat needle
• sharply pointed steel pivot
• inverted conical copper bowl
• glass cover
• copper ring
• ivory plate

--PericlesofAthens 02:22, 29 May 2007 (UTC)

Needle-and-bowl device

Could there be a confusion with static electricity? I cannot magnetize a needle by rubbing it with silk.Kinzele 16:10, 13 July 2007 (UTC)

Yeah, where did this come from? I know the Chinese rubbed needles with lodestone, and that did make them magnetic. But silk? That sounds kind of...stupid. Furthermore there's no citation for it.--PericlesofAthens 04:30, 18 July 2007 (UTC)

Why No Discussion Of Peter Peregrinus?

There is no detailed discussion of Peter Peregrinus, who described in detail two types of magnetic compass suitable for direction finding in 1269 A.D. He is also the founder of magnetic science. I can not understand the China bias in the invention of the compass and the subsequent lack of attention to European development. A separate section needs to be devoted to this and European development of compass. The current brief mentions are misleading to the reader. The European invention of the compass is one of the most important events in the history of the world. Since it allowed Europeans to discover America and open trade with India and China. In my view this is a major flaw. See [2]and [3]72.64.37.102 15:27, 19 July 2007 (UTC)

Reversal of Earth's magnetic field

This happens every few 100,000 years or so I read somewhere. This means a compass will point north due south (and vice versa). What would be a good discussion is to give the latest tehories on how this happens to the Earth's magnetic poles and when it is predicted to happen next on this here planet. Pomona17 13:03, 13 November 2007 (UTC)

Reversal of just the compass itself

Mention that one's compass might become reversed itself! Jidanni (talk) 00:59, 23 May 2010 (UTC)

Tritium replaced by Luminova

PLease include informataion that Tritium is now replaced by Luminova in compasses. See this article and this one

I couldn't actually see any refernce to the material used to make a compass readable at night. However, I'm confident that it usually wasn't/is't tritium. A luminous substance was painted onto the needle, used to mark the numbers and graduations, give an aiming arm for taking bearings. My understanding is that it was usually radium based. The key point is that it was luminous not illuminating. Tritium light sources are used to illuminate, ie like a light bulb, not as a paint, and were introduced in the 1960s, however, they only replaced luminous paint in some instances. Nfe (talk) 04:26, 5 June 2008 (UTC)

Besides battery illumination, there are not two, but THREE current methods of illuminating compass needles and dials for use in darkness or low light (unencapsulated radium-containing paint hasn't been applied for YEARS - for reasons why, see Madame Curie). The first is the old standard 'luminous' or phosphorescent paint, zinc sulfide (ZnS) - which has been around for years. It's not very bright. The second method has been called 'self-luminous', since it uses an encapsulated radioactive isotope of tritium for illumination. Tritium is found on several military models of compass that are sold to civilians (Silva of Sweden, Suunto, and Cammenga all make tritium models). Unlike radium-base paint, tritium gas emits only low energy beta particles (electrons) that are unable to penetrate the borosilicate glass walls of its capsule. This makes their use relatively safe. The third method is well-known to sailors who have purchased modern hand bearing compasses, though perhaps not to others. This third material is strontium aluminate(SrAl), aka LumiNova, which acts like a photoluminescent phosphor, and is typically called (in the compass trade) photoluminescent. Due to its bright blue-green glow, most people can usually tell right away when a compass part has an SrAl coating. Because SrAl is MUCH brighter than ordinary ZnS luminous paint, and because it is NOT a radioactive isotope, may see increasing use of SrAl on recreational compasses used for land navigation in years to come Article. Special:Contributions/Don01 (talk) 21:54, 26 November 2008 (UTC)

History of compass too long?

I think it's time to split off the History of compass section into another article. Comments? If there are no objections, I will do it next week.lk (talk) 08:20, 4 May 2008 (UTC)

Admittedly, it is fully 50% of the article. However, barring unexpected new discoveries, I don't see any part of the article ever getting much bigger...

I wouldn't be the one to revert it, as long as you craft a suitable wikilinked summary of the history to remain behind in the original article. I simply do NOT see a need.

Badly Bradley (talk) 18:48, 4 May 2008 (UTC)

The article is 60 kilobytes, which does put it in the running for splitting. The "History of compass" section would be a good choice: it includes a deal of speculation (referenced speculation, but all the same), whereas the sections starting "Modern compasses" are more definitely factual. Many users coming to this article are liable to be GPS owners, hikers, sailors, who are wondering "What is this thing, and how can I understand it better?" For them, the historical background is huge and rather inconclusive. Piano non troppo (talk) 17:49, 29 November 2008 (UTC)

Semi Protection for this page?

I've been watching this page for about a month, and it seems that every few days, this page is vandalised. Looking at the page history, it seems that this has been happening for a long time. I think it happens because school kids regularly look up compass for their school projects. Should this page be semi-protected? Any admins watching? lk (talk) 06:19, 21 May 2008 (UTC)

Liquid filled compasses

The statement that liquid filled hand held compasses were invented in 1936 is nonsense. Liquid filled hand held lensatic and prismatic compasses were available from several (4 or 5) suppliers(eg JH Steward & Son) in UK (mainly London)during World War 1, they were advertised for sale in military magazines. It's a less clear if they were also UK official service issue or when they first appeared. Perhaps similar compasses were also available in France and Germany.Nfe (talk) 04:11, 5 June 2008 (UTC)

I've removed the section on the invention of liquid compasses in 'history'. Do you have any references on when liquid filled compasses were invented? lk (talk) 18:55, 6 June 2008 (UTC)

No but it was before 1918, I've also got a copy of a 1918 British magazine article that states 'there are 4 well-known types of liquid compasses on the market, and these vary mostly in their method of reading the bearing'. These include JH Steward (prismatic), 'Blacker' type of wrist compass by Creagh-Osborne, Creagh-Osborne artillery pattern, the picture suggests its prismatic, and a lensatic compass with no manufaturer's name given.

I also have a advert by JH Steward Ltd, 406 Strand, London for a 'Lensatic Liquid Compass, Luminous', price five pounds and five shillings. Which was probably about a weeks pay for a working man in those days. I think this advert is from 1917/8 Nfe (talk) 08:03, 7 June 2008 (UTC)

If you ever find more information or a citation about when the liquid filled compass was invented, please do update the pages. Thanks. lk (talk) 17:29, 8 June 2008 (UTC)

Other aspects

Another type of compass used in late 19th and early 20th century was the 'trough compass'. This was used with plane tables. Another matter was/is compass 'dip', this seems to mean the tilt of a magnetic compass needle from the horizontal and varies depending where it is.Nfe (talk) 05:10, 6 June 2008 (UTC)

I believe the issue of 'compass dip' is addressed in the section titled 'balancing the compass'. lk (talk) 17:29, 8 June 2008 (UTC)

Lacking info about modern compasses

This page needs more history concerning about liquid filled, prismatic, lensatic and surveyors compasses. Also needs more info about the new electronic compasses that are sometimes built into watches and GPS devices. If anyone knows anything about these devices, could he/she please add to the page. Thanks. lk (talk) 17:29, 8 June 2008 (UTC)

A few comments about the U.S. military lensatic compass are in order. While I own one myself, and realize it is beloved by many, this design is frequently oversold. It is not 'more rugged' than most other compasses (including acrylic protractor compasses used by many more military forces than the U.S. Army/Marines). First, it does not have an airtight capsule filled with liquid or inert gas, so it's NOT waterproof, despite claims from the manufacturer(s) over the years (remember what happens to binoculars that are sealed with ordinary air?). Water can enter, despite the seal, and humid air can also condense inside the capsule and corrode or freeze up the dial. It happens! Second, it is NOT shockproof. The military lensatic has a long pivot due to its deep well design, so it is vulnerable to bent pivots when dropped on hard surfaces, like a rock, or on concrete. Most people don't realize that the U.S. military drop tests random samples of military lensatic compasses by dropping them onto plywood tables covered with 10 cm (4 inches) of plastic-covered dry sand from 90 cm (3 feet) heights! Remember, the test is NOT "does the card still rotate", but rather "does it still read within a degree of magnetic north". In fact, the baseplate compass is better able to withstand drops with its light weight, short pivot, and liquid-damped capsule. It also tends to require less frequent servicing, unit for unit. The British Army noted this years ago when they adopted the baseplate design. Third, while some baseplate compasses can be read to 1-degree, the lensatic still has a compass card design dating to the 1930s, with only five-degree markings. It takes a very skilled individual to interpolate 1-degree splits with a standard Cammenga. One could use the mils and convert, of course, but what's the point of trying? - the military only requires 40 mil (2.25 degree) inherent accuracy from a brand-new lensatic compass anyway. So the claim of 'most accurate' doesn't begin to apply to this model in comparison to several other designs (Brunton M2, Brunton 54LU (Silva 54), Suunto KB-14.LK (talk) 15:59, 5 December 2008 (UTC)

History: Sorting by type of compass

Sorting the history section by the different types of compasses does the complicated subject more justice, and is certainly more convenient for the reader than a confusing patchwork of geographical subcategories. I also tried to verify sources given and corrected those I had access to. Regards Gun Powder Ma (talk) 03:41, 11 September 2008 (UTC)

I ordered the compasses by type and function, so that the structure of the article is now more sound and reader friendly. If there are any objections to a systemically ordered history section, they should be brought forward here, not by making unexplained reverts. The more so, since the user does not seem to have read the sources cited, and blindly double posted material from the astronomy section in that about the Islamic world. Regards Gun Powder Ma (talk) 01:17, 3 January 2009 (UTC)

I Invite the user again to explain his enigmatic edits to a wider audience. Gun Powder Ma (talk) 16:50, 8 January 2009 (UTC)

POV pushing in the lead

The invention of the compass deserves a place in the lead. The knowledge of magnetism in Ancient Greece does not. This is similar to editing the article on the internal combustion engine to emphasize the discovery of petroleum in the ancient Middle East and leaving out the invention of the engine in Germany in the 19th century. lk (talk) 07:53, 11 September 2008 (UTC)

That isn't POV pushing; that is cruft. --Una Smith (talk) 16:52, 5 October 2008 (UTC)

Is this article protected?

When I display the article, it shows a Semi-protection icon on the upper right side. However, we seem to have been suffering a spate of vandalism attacks from anonymous IPs. How is that possible if the article is semi-protected? Anyone know what is going on? LK (talk) 04:27, 13 January 2009 (UTC)

It seems that the semi-protection for the page has expired. I'm going to request that it be reinstated, since as soon as it expired we have been experiencing about 1 vandalism per day, and almost all the edits since are either vandalism or reverts of vandalism. If anyone objects, please do so below. Remember, silence implies consent. LK (talk) 16:34, 18 January 2009 (UTC)

2 of the arguments against independent European invention of the compass are false

At least 2 of the arguments in the article against independent European invention of the compass are wrong. In the first case, the earliest European to mention a compass talks about a dry mounted compass (see Neckham's 'De Utensilibus'.) Nowhere does he mention a floating compass.

Second, the ancient Greeks knew about magnetism, so the Europeans would likely know about magnetism. All our sources from the ancient Greeks came from either Medieval Europeans copying ancient Greek works, or from Arabic sources later transllated into Latin during the middle ages.

Glenn Beard, Michigan. —Preceding unsigned comment added by 66.51.147.97 (talk) 21:27, 14 March 2009 (UTC)

Awesome, now you just have to find sources for this information and edit the page! 174.49.43.243 (talk) 06:23, 27 May 2009 (UTC)

Wrist and small clip compasses

In Ski-O and MTB-O small compasses attached to the mapboard or the wrist exists. A short sections about these modern compasses are needed. An example product here.--Kslotte (talk) 12:23, 1 July 2009 (UTC)

pliny the elder

• The lack of evidence of prior knowledge in Europe of magnetism or how to induce it in an iron rod.

CHAP. 42.—THE METAL CALLED LIVE IRON. We shall speak of the loadstone in its proper place,1 and of the sympathy which it has with iron. This is the only metal that acquires the properties of that stone, retaining them for a length of time, and attracting other iron, so that we may sometimes see a whole chain formed of these rings. The lower classes, in their ignorance, call this "live iron," and the wounds that are made by it are much more severe. This mineral is also found in Cantabria, not in continuous strata, like the genuine loadstone, but in scattered fragments, which they call "bullationes."2 I do not know whether this species of ore is proper also for the fusion of glass,3 as no one has hitherto tried it; but it certainly imparts the same property as the magnet to iron. The architect Timochares4 began to erect a vaulted roof of loadstone, in the Temple of Arsinoë,5 at Alexandria, in order that the iron statue of that princess might have the appearance of hanging suspended in the air:6 his death, however, and that of King Ptolemæus, who had ordered this monument to be erected in honour of his sister, prevented the completion of the project.

1 B. xxxvi. c. 25.

2 Properly "bubbles," or "beads."

3 See B. xxxvi. c. 66. In the account of the loadstone referred to above, he informs us that this mineral was employed in the formation of glass.—B. Beckmann is of opinion that Manganese is here alluded to. See Vol. II. p. 237.

4 Another reading is "Dinochares," or "Dinocrates," for an account of whom, see B. v. c. 11, and B. vii. c. 38.

5 Wife and sister of Ptolemy Philadelphus. See B. vi. c. 33, and B. xxxvi. c. 14.

6 Some accounts state that the statue was to be of brass, and the head of iron. It is said that the same thing was attempted with respect to the statue of Mahomet, in his tomb at Medina.—B. The Natural History. Pliny the Elder. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855.

this shows magnets were known in classic timesJ8079s (talk) 02:54, 4 July 2009 (UTC)

Critique of Compass Article

The article is well written and easy to read. The facts are well researched and accurate. The sources are complete, authoritative and cover a wide time frame of publishing. It is good to not only use older sources, but the most recent source included was published in 2007. The images and descriptions were good and added to the article. They were relevant and not just distracting. The subject was covered throughly without many inaccurate contributions. It would be interesting to add more about the argument on wether the compass' technology migrated from China to Europe or if by chance it was also invented in Europe with a similar design. There is not much about that in the article. Also, there is a ton of information about the history of the compass in China and then in contrast the European history with the compass was a very brief summary spanning a long period of time. It also does not address the argument of wether the compass was invented or shared, but just says it was reportedly used starting in 1187. These few improvements would help this article.