Talk:Compass

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Contents 1 degrees 2 Heavily Edited some portions, added a section + picture on Han dynasty Spoon compass 3 Are all compasses magnetic? 4 Soundings 5 Who picked up compasses from whom? 6 Lensatic? 7 Compass usage section 8 Compass spoon 9 accuracy of article 10 The true mariner's compass 11 The supposed Olmec invention 12 Good edit

[edit] 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

[edit] 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)

[edit] 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

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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.

[edit] 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