Compass
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.
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 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.
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, this trick did not seem to get used by the Chinese for naval navigation. The knowledge of the behavior of long thin magnets and lodestones had to move to Europe for that to occur. European naval powers were quick to identify the value of having a compass on board. Celestial navigation used the constellations and known stars to identify directions. This was of little or no use in foggy conditions, with overcast sky or during the day. Early compasses often consisted of a natural lodestone which was placed on a float in a protected container of water.
A magnetic rod is required. This can be created by aligned 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 should be labeled and generally has a pointer to North.
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. Thihs preserves the horizontal position.
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. Tthe 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, gyrocompass, Gyrosin compass, gyrostatic compass, inertial navigation system, radio compass, radio direction finder
In math and drafting, device known as a compass (or pair of compasses) is used by mathematicians and craftsmen in geometry to draw or inscribe a circle or arc. Simply, this type of compass is used as a drafting instrument used for drawing circles.
In carpentry, architecture, and shipbuilding, a compass is a curve (or bent) circular form. A compass plane is a craftsman plane, which has a convex direction length on the underside, for smoothing the concave faces of curved woodwork. A Compass saw (or fret saw or keyhole saw) is a narrow blade a saw that cuts a curve. A compass timber is a curved (or crooked) timber. A compass window is a circular bay window (or oriel window).
A Surveyor's compass (or circumferentor) is an measuring instrument used in surveying horizontal angles.
In Botany, a compass plant {or compass flower; also called rosinweed} is an American prairies plant and is similar to a little sunflower. It's scientific name is Silphium laciniatum. The compass plant has it's lower and root leaves vertical. Compass plants tend to align their edges north and south.
COMPASS is an acronym for COMPrehensive ASSembler. COMPASS is a assembly language on Control Data Corporation computers.
In Law, a compass is to purpose (or intend) something. It is an indivudaul that is imagining something or to plot a plan. Compassing signifies a purpose (or design) of the mind (or will), and not carrying such design to effect.Navigation
History of the navigational compass
Construction of a simple compass
Modern navigational compasses
Points of the compass
Main article: Boxing the compassExternal Links, Resources, and References
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