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Compass (including recent related patents.)
CompassThis article is about the navigational tool. For other meanings, see Compass (disambiguation)A compass (or mariner's compass) is navigational instrument for finding directions. It consists of a magnetised pointer free to align itself accurately with Earth's magnetic field. A compass provides a known reference direction which is of great assistance in navigation. The cardinal points are north, south, east and west. A compass can be used in conjunction with a clock and a sextant to provide a very accurate navigation capability. This device greatly improved maritime trade by making travel safer and more efficient. Navigational compassmariner's compass (Larger) A compass can be any magnetic device using a needle to indicate the direction of the magnetic north of a planet's magnetosphere. Any instrument with a magnetized bar or needle turning freely upon a pivot and pointing in a northerly and southerly direction can be considered a compass. A compass dial is a small pocket compass with a sundial. A variation compass is a specific instrument of a delicate type of construction. It is used by observing variations of the needle. A gyrocompass can also be used to ascertain true North. Table of contents showTocToggle("show","hide") 1 History of the navigational compass 2 Construction of a simple compass 3 Modern navigational compasses 4 Points of the compass 5 External Links, Resources, and References History of the navigational compass Compasses were initially used in mysticism in ancient China. The first known use of Earth's magnetic field in this way occurred in ancient China as a spectacle. Arrows were cast similarly to dice. These magnetised arrows aligned themselves pointing north, impressing the audience. Curiously, it took some time for this trick to get used by the Chinese for naval navigation, but by the 11th or early 12th century it had become common. 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. 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. Difficulties arose where the sea is too deep for soundings and conditions are continually overcast or foggy. Thus the compass was not of the same utility everywhere. For example, the Arabs could generally rely on clear skies in navigating the Persian Gulf and the Indian Ocean (as well as the predictable nature of the monsoons). This may explain in part their relatively late adoption of the compass. Mariners in the relatively shallow Baltic made extensive use of soundings. In the Mediterranean, however, the practice from ancient times had been to curtail sea treval between October and April, due in part to the lack of dependable clear skies during the Mediterrean winter (and much the sea is too deep for soundings). With improvements in dead reckoning methods, and the development of better charts, this changed during the second half the 13th century. By around 1290 the sailing season could start in late January or February, and end in December. The additional few months were of considerable economic importance; it enabled Venetian convoys, for instance, to make 2 round trips a year to the eastern Mediterranean, instead of 1. Around the same time traffic between the Mediterranean and northern Europe increased, and one factor may be that the compass made traversal of the Bay of Biscay safer and easier. Construction of a simple compass A magnetic rod is required. This can be created by aligning an iron or steel rod with Earth's magnetic field and then tempering or striking it. However, this method produces only a weak magnet so other methods are preferred. This magnetised rod (or magnetic needle) is then placed on a low friction surface to allow it to freely pivot to align itself with the magnetic field. It is then labeled so the user can distinguish the north-pointing from the south-pointing end; in modern convention the north end is typically marked in some way, often by being painted red. Modern navigational compasses Modern navigational compasses hold a magnetized needle inside a fluid-filled capsule; the fluid causes the needle to stop quickly rather than oscillate back and forth around magnetic north. Other features common on modern handheld compasses are a baseplate with rulings for measuring distances on maps, a rotating bezel for measuring bearings of distant objects, and a sighting mirror that lets the user see both the compass needle and a distant object at the same time. Many modern navigational compasses also include an adjustment for magnetic declination, the offset between magnetic north and true north, which varies from place to place on the Earth's surface. Mariner's compasses can have two or more magnetic needles permanently attached to a compass card. These move freely on a pivot. A mariner reads this for a reference box mark that representd the ship's headings. The card is divided into thirty-two points (known as rhumbs). The glass-covered box (or bowl) contains a suspended gimbal within a binnacle. This preserves the horizontal position. Points of the compass Main article: Boxing the compass The thirty-two points of division of the mariner's compass card. The corresponding dividing points of the horizon circle with four markings of the directions [i.e., east, west, north, and south]. These are called cardinal points. The rest are named from their respective directions. A compass card is a circular card that is attach to the needles of a compass. On the compass card are marked the thirty-two points. See also: Azimuth compass, Beam compass, coordinates, fluxgate compass, gyrocompass, Gyrosin compass, gyrostatic compass, inertial navigation system, radio compass, radio direction finder External Links, Resources, and References
This article is adapted from from Wikipedia All Wikipedia article text is available under the terms of the GNU Free Documentation License His Dark Materials Trilogy: The Golden Compass / The Subtle Knife / The Amber Spyglass by Philip Pullman Be Expert with Map and Compass by Bjön Kjellström The Golden Compass (His Dark Materials, Book 1) by PHILIP PULLMAN Career Compass by Peggy Simonsen Mariner's Compass Quilts: New Directions by Judy Mathieson Inner Compass: An Invitation to Ignatian Spirituality by Margaret Silf The Golden Compass (His Dark Materials, Book 1) by PHILIP PULLMAN Land Navigation Handbook: The Sierra Club Guide to Map and Compass by William S. Kals The Golden Compass (His Dark Materials, Book 1) by PHILIP PULLMAN Compass Of The Soul: 52 Ways Intuition Can Guide You To The Life Of Your Dreams by Lynn Robinson Wilderness Navigation: Finding Your Way Using Map, Compass, Altimeter, & Gps by Bob Burns Ruling the Waves: Cycles of Discovery, Chaos, and Wealth, from the Compass to the Internet by Debora L. Spar Compass & Map Navigator (rev): The Complete Guide to Staying Found by Michael Hodgson The Compass of Zen by Seung Sahn The Moral Compass of the American Lawyer : Truth, Justice, Power, and Greed by Carol M. Langford Recent Compass related patents From USPTO: 6718217: Digital audio tone evaluating system 6717654: Combined range-finding, sighting and scanning system and method 6717524: Voice acquisition system for a vehicle 6716879: Methods for anti-tumor therapy 6715681: Scanning module for single line and raster scanning using dual lasers 6715238: Fall protecting safety device 6714866: Methods and apparatus for installation alignment of equipment 6714857: System for remote monitoring of a vehicle and method of determining vehicle mileage, jurisdiction crossing and fuel consumption 6714778: Context sensitive web services 6714481: System and method for active sonar signal detection and classification 6714480: Determination of anisotropic moduli of earth formations 6714334: Electrochromic device having a seal including an epoxy resin cured with a cycloaliphatic amine 6714141: Electronic cockpit vision system 6714127: Emergency warning system for vehicles 6713956: Display module including a plate for heat dissipation and shielding 6712312: Reconnaissance using unmanned surface vehicles and unmanned micro-aerial vehicles 6712274: Permanent visual shock indicator 6712141: Method and apparatus for deployment, mounting and coupling of downhole geophones 6712017: Method and arrangement relating to inspection 6711949: Remote fluid level detection system 6711693: Method for synchronizing plurality of time of year clocks in partitioned plurality of processors where each partition having a microprocessor configured as a multiprocessor backplane manager 6711499: Navigation system with run-time training instruction 6711474: Automobile personal computer systems 6711355: Camera having rotary optical encoder 6710749: Satellite locator system 6710031: Protein having antithrombotic activity and method for producing the same 6708783: Three-dimensional steering tool for controlled downhole extended-reach directional drilling 6708764: Undulating well bore 6708424: Shoe with naturally contoured sole 6708415: Magnetic compass structure 6708114: Integrated forest data collection system and method 6708109: Accurate targeting from imprecise locations 6708090: Method, apparatus and computer program product for managing line-of-sight communications 6708064: Modulation of the brain to affect psychiatric disorders 6707421: Driver information system 6707395: Circuit configuration for position lights 6705976: Exercise apparatus 6705174: Apparatus and method for gyroscopic propulsion 6704563: Systems and methods for prerating costs for a communication event 6704276: Self-contained, multi-axis recordable and storage apparatus 6704246: Sound-ranging system with submarine buoy 6704108: 3D grating optical sensor comprising a diffusion plate for conducting chromatometry with color constancy performance 6703973: Guiding vehicle in adjacent swaths across terrain via satellite navigation and tilt measurement 6703944: Technique for effectively maintaining a safe distance between a vehicle and an object 6703941: Trainable transmitter having improved frequency synthesis 6702776: Blood vessel catheter 6702582: Device and method for solving circles 6702229: Method, apparatus and article to display flight information 6701631: Convertible directional azimuth and dip measuring modular compass and method |
