compass

(kŭm'pəs, kŏm'-)
n.

1. 1. A device used to determine geographic direction, usually consisting of a magnetic needle or needles horizontally mounted or suspended and free to pivot until aligned with the earth's magnetic field.
   2. Another device, such as a radio compass or a gyrocompass, used for determining geographic direction.
2. A V-shaped device for describing circles or circular arcs and for taking measurements, consisting of a pair of rigid, end-hinged legs, one of which is equipped with a pen, pencil, or other marker and the other with a sharp point providing a pivot about which the drawing leg is turned. Also called pair of compasses.
3. 1. An enclosing line or boundary; a circumference: outside the compass of the fence. See synonyms at circumference.
   2. A restricted space or area: four huge crates within the compass of the elevator.
   3. Range or scope, as of understanding, perception, or authority: "Lacking a coherent intellectual and moral commitment, [he] was forced to find his compass in personal experience" (Doris Kearns Goodwin). See synonyms at range.
4. Music. See range (sense ).

tr.v., -passed, -pass·ing, -pass·es.

1. To make a circuit of; circle: The sailboat compassed the island.
2. To surround; encircle. See synonyms at surround.
3. To understand; comprehend.
4. To succeed in carrying out; accomplish. See synonyms at reach.
5. To scheme; plot.

adj.

1. Forming a curved configuration.
2. Semicircular. Used of bow windows.

[Middle English compas, circle, compass, from Old French, from compasser, to measure, from Vulgar Latin *compassāre, to pace off : Latin com-, com- + Latin passus, step; see pace¹.]

compassable com'pass·a·ble adj.

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The journal of the Melbourne University literature club, was published irregularly 1956-63. Originally intended as a workshop journal publishing experimental undergraduate creative writing, Compass included among its early contributors now-established figures such as Chris Wallace-Crabbe and Bruce Dawe. Among its editors have been the poets Wallace-Crabbe, Clive Faust and Andrew Taylor.

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For more information on compass, visit Britannica.com.

Background

A compass is a device used to determine direction on the surface of the earth. The most familiar type of compass is the magnetic compass, which relies on the fact that a magnetic object tends to align itself with Earth's magnetic field. Other types of compasses determine direction by using the position of the Sun or a star, or by relying on the fact that a rapidly spinning object (a gyroscope) tends to resist being turned away from the direction in which its axis is pointing.

The basic parts of a magnetic compass are the needle (a thin piece of magnetic metal), the dial (a circular card printed with directions), and the housing (which holds the other parts in place). Inexpensive compasses, generally used as toys, may have no other parts. Compasses intended for more serious purposes usually have other parts to make them more useful. These other parts may include lids, covers, or cases to protect the compass; sights making use of lenses, prisms, or mirrors to enable the user to determine the direction of an object in the distance; and a transparent baseplate marked with a scale of inches or millimeters so that the compass can be used directly on a map.

An important feature found on many compasses is automatic declination adjustment. Declination, also known as variance, is the difference between magnetic North (the direction to which the needle points) and true North. This difference exists because Earth's magnetic field does not align exactly with its North and South poles. The amount of declination varies from place to place on Earth's surface. If the amount of declination is known for a particular area, automatic declination adjustment allows the compass user to read true direction directly from the compass rather than having to add or subtract the amount of declination every time the compass is used.

History

By 500 B.C., it was known that lodestone, a naturally occurring form of iron oxide also known as magnetite, had the ability to attract iron. No one knows where or when it was first noticed that a freely moving piece of lodestone tended to align itself so that it was pointing North and South. Written records indicate that the Chinese used magnetic compasses by 1100 A.D., western Europeans and Arabs by 1200 A.D., and Scandinavians by 1300 A.D.

Early compasses consisted of a piece of lodestone on a piece of wood, a cork, or a reed floating in a bowl of water. Somewhat later, a needle of lodestone was pivoted on a pin fixed to the bottom of a bowl of water. By the thirteenth century, a card marked with directions was added to the compass. By the middle of the sixteenth century, the bowl of water was suspended in gimbals, which allowed the compass to remain level while being used aboard a ship being tossed by the ocean.

In 1745, the English inventor Gowin Knight developed a method for magnetizing steel for long periods of time. This allowed needles of magnetized steel to replace needles of lodestone. During the early nineteenth century, iron and steel began to be used extensively in shipbuilding. This caused distortions in the operation of magnetic compasses. In 1837, the British Admiralty set up a special commission to study the problem. By 1840, a new compass design using four needles was so successful at overcoming this difficulty that it was soon adopted by navies around the world.

Until the middle of the nineteenth century, navigators used both dry-card compasses, in which the needle pivoted in air, and liquid compasses, in which the needle pivoted in water or another liquid. Dry-card compasses were easily disturbed by shocks and vibrations, while liquid compasses tended to leak and were difficult to repair. In 1862, improvements in the design of liquid compasses quickly made the dry-card compass obsolete for naval use. By World War 1, the British Army used liquid compasses on land, and liquid compasses are still the standard for the best hand held magnetic compasses.

Raw Materials

The needle of a magnetic compass must be made of a metallic substance, which can be magnetized for an extended period of time. The most common substance used for compass needles is steel. Steel is an alloy of iron and a small amount of carbon. The raw materials used to produce steel are iron ore and coke (a carbon-rich substance produced by heating coal to a high temperature in the absence of air). Other substances such as cobalt are often added to the steel to produce alloys, which can be magnetized for a very long time.

The housing that holds the needle in place is often made of acrylic plastic. Acrylic plastics are produced from various derivatives of the chemical compound acrylic acid. The most important of these derivatives is methyl methacrylate. Thousands of molecules of methyl methacrylate are linked into a long chain to form polymethyl methacrylate, known by the trade names Lucite and Plexiglas. Polymethyl methacrylate has the advantages of being strong and transparent.

The Manufacturing
Process

Making the needle

• Iron ore, coke, and limestone are heatedI in a blast furnace by hot pressurized air. The coke releases heat, which melts the ore, and carbon monoxide, which reacts with iron oxides in the ore to release iron. The limestone reacts with impurities in the ore such as sulfur to form slag, which floats on the molten iron and is removed. The product of this process is pig iron, which contains about 90% iron, 3-5% carbon, and various impurities.
• To remove the impurities and most of the carbon, oxygen is blasted into the molten pig iron under high pressure. The impurities are released as slag and the carbon is released as carbon monoxide. The remaining molten steel is poured into molds and allowed to cool into ingots weighing thousands of pounds each.
• The ingots are heated to about 2,200° F (1,200° C) and rolled between grooved rollers to form slabs. The slab is cut with giant shears, reheated, and rolled again until it is the proper thickness for needles. The thin sheet of steel is then stamped with a sharp die in the shape of the needle. The process is repeated to produce many needles from a single sheet of steel.
• The needles are shipped from the steel manufacturer to the compass manufacturer. At the compass factory, the needles are inserted by hand into holders on an automated turntable. As the turntable spins the "North" end of the needle is sprayed with red paint and the "South" end of the needle is sprayed with white paint. As the needle continues, it is exposed to a strong magnetic field produced by an electronic magnetizer.
• The magnetized needles are removed from the turntable and the paint is allowed to dry. The needles may also be baked in an oven to dry the paint. They are then placed in storage until needed for assembly.

Making the housing

• Polymethyl methacrylate is formed by subjecting a solution of methyl methacrylate to light, heat, or various chemical catalysts. The components of the compass housing are then formed by a process known as injection molding. Polymethyl methacrylate is heated until it melts into a liquid. The molten plastic is then injected into a mold in the shape of the desired product. The mold is allowed to cool, opened, and the solid plastic is removed. The various plastic components are shipped from the plastic manufacturer to the compass manufacturer and stored until needed.

Assembling the compass

• When the compass manufacturer receives an order from a wholesaler, the plant manager arranges for the necessary parts to be issued from storage to workers on an assembly line. As the compass progresses along the assembly line, plastic components are snapped together. Some plastic components move through printers, which stamp them with markings such as a company logo, or with scale markings for use with maps.
• One of the most critical components of a compass is the vial, which holds the needle. The needle is balanced on a pivot to enable it to move freely. Inexpensive compasses may have a steel pivot, but the best compasses have jeweled pivots in order to resist wear. Jeweled pivots are made of very hard materials such as an osmium-iridium alloy and are capped with a material such as artificial sapphire.
• The vials are dipped in a liquid that will serve as a dampener. A dampener is a substance that causes the needle to come to rest more quickly when it is disturbed. Various liquids are used for dampeners. These liquids must be transparent and must not react with any of the components of the compass. A typical liquid used for this purpose might be a mixture of ethyl alcohol and water.
• The vials filled with liquid are sealed using sonic welding. This avoids exposing the needle to heat, which could disturb its magnetism. In this process, ultra-sonic waves are used to melt the plastic at the place where the vial is to be sealed. The plastic is then allowed to solidify, forming a tight seal. Assembly of the compass continues as the sealed vial is snapped onto a baseplate.
• The completed compasses are packed in ways that protect them from theft and damage. They may be packed in clam packing, in which a plastic container resembling a clam shell surrounds the compass. They may also be packed in blister packing, in which a plastic bubble attached to a flat piece of cardboard surrounds the compass. The packaged compasses are placed in card-board boxes and shipped to the wholesaler.

Quality Control

At each step of the manufacturing process, the various components which make up the compass are visually inspected and removed if they are defective. Common imperfections include printing errors and bubbles in the dampening liquid. The most important part of the compass, the magnetic needle, is very unlikely to be defective. The few cases in which the needle does not work properly are usually caused by the consumer exposing the needle to a strong magnetic or electric field. In such cases, the needle may be remagnetized so that it points backwards, with the "North" end pointing south.

The most important part of quality control for a magnetic compass is the user's responsibility for learning how to use the compass properly. Compasses are very reliable instruments, but they are useless if the user does not know how to use them correctly. Knowing how to allow for declination is a critical skill in using a magnetic compass. In some parts of the world, failure to allow for declination could lead to an error of several degrees, causing the user to wind up many miles from the intended destination. An excellent way to learn proper use of a compass is to participate in the sport of orienteering. This sport involves using a map and compass to compete with others in finding a path from a starting point to a selected destination.

The Future

During the 1970s, the U.S. Navy began an ambitious project known as the Global Positioning System (GPS). The GPS project was taken over by the U.S. Air Force in the 1980s and completed in June 1993. GPS consists of a system of 24 satellites containing atomic clocks that broadcast extremely accurate time signals to Earth. By analyzing the exact time these signals arrive at a receiver, it is possible to determine position with great accuracy. Devices not much larger than an ordinary compass can determine location within about 100 ft (30 m).

At first glance, it may seem that GPS threatens to make the magnetic compass obsolete. In fact, the exact opposite is true. Because GPS indicates position but not direction, manufacturers of GPS equipment recommend that it be used with a compass. Compasses also have the advantage of requiring no energy supply. Unlike GPS, compasses can be used when heavy tree cover or large buildings block the reception of electronic signals. Although GPS promises to revolutionize navigation, traditional compasses will remain a vital component in how we find our way around.

Where to Learn More

Books

Hogan, Paula Z. The Compass. Walker and Company, 1982.

Randall, Glenn. The Outward Bound Map and Compass Handbook. Lyons and Burford, 1989.

Periodicals

"Consumer's Guide to Compasses." Mechanix Illustrated (April 1978): 9.

Kleppner, Daniel. "Where I Stand." Physics Today (January 1994): 9-11.

[Article by: Rose Secrest]

noun

1. A line around a closed figure or area: ambit, circuit, circumference, perimeter, periphery. See edge/center.
2. The ability or power to seize or attain: capacity, grasp, range, reach, scope. See ability/inability.
3. An area within which something or someone exists, acts, or has influence or power: ambit, extension, extent, orbit, purview, range, reach, realm, scope, sphere, sweep, swing. See territory.

verb

1. To encircle with or as if with a band: band, begird, belt, cincture, encompass, engirdle, gird, girdle, girt, ring. Archaic engird. See edge/center.
2. To shut in on all sides: begird, beset, circle, encircle, encompass, environ, gird, girdle, hedge, hem, ring, surround. See open/close.
3. To perceive and recognize the meaning of: accept, apprehend, catch (on), comprehend, conceive, fathom, follow, get, grasp, make out, read, see, sense, take, take in, understand. Informal savvy. Slang dig. Chiefly British twig. Scots ken. Idioms: gethavea handle on, get the picture. See understand/misunderstand.
4. To perceive directly with the intellect: apprehend, comprehend, fathom, grasp, know, understand. Scots ken. See knowledge/ignorance.

An instrument for drawing circles, measuring the distance between two points, etc.; consists of two pointed legs, movable on a joint or pivot, usually made so that one of the points can be detached for the insertion of a pen, extension, etc.

compass

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Guidance. Finding one's way out of situation in which one feels lost. We also talk about our "moral compass," which guides us in making ethical choices.

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For a list of words related to compass, see:

• Maps and Cartography - compass: directional device with magnetic needle pivoting freely and pointing north
• Mathematical Tools - compass: instrument used to draw arcs and circles
• Measuring Devices - compass: instrument for drawing or measuring circles, consisting of two movable, rigid legs hinged at one end
• Measuring and Marking Tools - compass: instrument consisting of two movable legs hinged at one end, used to draw arcs and circles
• Avionics and Instrumentation - compass: magnetic compass
• Parts of Ships, Sails, and Equipment - compass: navigational instrument with magnetized needle indicating north, used to determine heading
• Graphic Design - compass: instrument for drawing arcs and circles
• Dimensions and Directions - compass: enclosing limits of any space; space within such limits
• Shapes - compass: (adj) curved; forming a curve or an arc

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See words rhyming with "compass."

  See crossword solutions for the clue Compass.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - kompas, omkreds, grænse, rækkevidde, spænd, passer
v. tr. - omgive, opnå, fatte, udpønse, gå rundt om
adj. - krum, rund, kompas-

idioms:

• compass point    kompasstreg, verdenshjørne

Nederlands (Dutch)
kompas, (mv) passer, (stem)bereik, omtrek, (om-/be)vatten, bereiken, beramen

Français (French)
n. - boussole, compas, étendue, portée, rayon, (Naut) compas, (Mus) étendue
v. tr. - encercler, entourer, saisir, faire le tour de (terre, océan) (arch)
adj. - au compas

idioms:

• compass point    point cardinal

Deutsch (German)
n. - Kompass, Rahmen, Bereich, Zirkel
v. - erfassen, vollbringen, umgeben
adj. - gewölbt, gekrümmt

idioms:

• compass point    Windrichtung

Ελληνική (Greek)
n. - πυξίδα (κν. μπούσουλας), διαβήτης, περιοχή, όρια, έκταση, εύρος, φάσμα, γκάμα
v. - περιτριγυρίζω, περιβάλλω, περιλαμβάνω, περικλείω, απεργάζομαι

idioms:

• compass point    ρόμβος/σημείο πυξίδας

Italiano (Italian)
compasso, bussola

idioms:

• compass point    punto cardinale

Português (Portuguese)
n. - compasso (m)
v. - circundar, planejar, entender

idioms:

• compass point    ponto (m) de compasso

Русский (Russian)
компас, предел, (множ.) циркуль

idioms:

• compass point    сторона света

Español (Spanish)
n. - brújula, compás
v. tr. - contornear, encorvar, utilizar la brújula o el compás
adj. - circular, curvo

idioms:

• compass point    punto de la brújula

Svenska (Swedish)
n. - kompass, passare, omkrets, område
v. - omge, gå runt, fatta, uppnå, planlägga

中文（简体）(Chinese (Simplified))
罗盘, 圆规, 指南针, 境界, 周围, 用指南针, 弯的, 曲的, 弧形的, 半圆的

idioms:

• compass point    方位点

中文（繁體）(Chinese (Traditional))
n. - 羅盤, 圓規, 指南針, 境界, 周圍
v. tr. - 用指南針
adj. - 彎的, 曲的, 弧形的, 半圓的

idioms:

• compass point    方位點

한국어 (Korean)
n. - 나침반, 제도용 컴퍼스, 한계
v. tr. - 주위를 돌다, 이해하다, 궁리하다
adj. - 구부러진, 아치형의

日本語 (Japanese)
n. - 羅針盤, コンパス, 範囲, 限界, 周囲
v. - 囲い込む, 企てる

idioms:

• compass point    方位

العربيه (Arabic)
‏(الاسم) بوصله, دائرة, حدود, نطاق, مجال, مدى, فرجال (فعل) حصر, طوق, أدار, أحاط ب‏

עברית (Hebrew)
n. - ‮מצפן, תחום, גבול‬
v. tr. - ‮הבין, השיג, הקיף‬
adj. - ‮קשתי‬

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