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( Compass)
A compass is a navigational instrument for determining direction relative to the Earth's magnetic poles. It consists of a magnetized pointer (usually marked on the North end) free to align itself with Earth's magnetic field. The compass greatly improved the safety and efficiency of travel, especially ocean travel. A compass can be used to calculate heading, used with a sextant to calculate latitude, and with a marine chronometer to calculate longitude. It thus provides a much improved navigational capability that has only been recently supplanted by modern devices such as the Global Positioning System (GPS). A compass is any magnetically sensitive device capable of indicating the direction of the magnetic north of a planet's magnetosphere. The face of the compass generally highlights the cardinal points of north, south, east and west. Often, compasses are built as a stand alone sealed instrument with a magnetized bar or needle turning freely upon a pivot, or moving in a fluid, thus able to point in a northerly and southerly direction. The compass was invented in ancient China sometime before the 2nd century, and was used for navigation by the 11th century. The dry compass was invented in medieval Europe around 1300.[1] This was supplanted in the early 20th century by the liquid-filled magnetic compass.[2] Other, more accurate, devices have been invented for determining north that do not depend on the Earth's magnetic field for operation (known in such cases as true north, as opposed to magnetic north). A gyrocompass or astrocompass can be used to find true north, while being unaffected by stray magnetic fields, nearby electrical power circuits or nearby masses of ferrous metals. A recent development is the electronic compass, or fibre optic gyrocompass, which detects the magnetic directions without potentially fallible moving parts. This device frequently appears as an optional subsystem built into GPS receivers. However, magnetic compasses remain popular, especially in remote areas, as they are cheap, durable, and require no electrical power supply.[3] Prior to the introduction of the compass, position, destination, and direction at sea was primarily determined by the sighting of landmarks, supplemented with the observation of the position of celestial bodies. Ancient mariners often kept within sight of land. The invention of the compass enabled the determination of heading when the sky was overcast or foggy. And, when the sun or other known celestial bodies could be observed, it enabled the calculation of latitude. This enabled mariners to navigate safely far from land, increasing sea trade, and contributing to the Age of Discovery Based on Krotser and Coe's discovery of an Olmec hematite artifact in Mesoamerica, radiocarbon dated to 1400-1000 BC, astronomer John Carlson has suggested that the Olmec might have discovered and used the geomagnetic lodestone compass earlier than 1000 BC. If true, this "predates the Chinese discovery of the geomagnetic lodestone compass by more than a millennium".[4] Carlson speculates that the Olmecs used similar artifacts as a directional device for astrological or geomantic purposes. The artifact is part of a polished hematite (lodestone) bar with a groove at one end (possibly for sighting). The artifact now consistently points 35.5 degrees west of north, but may have pointed north-south when whole. Other researchers have suggested that the artifact is actually a constituent piece of a decorative ornament.[5] Several other hematite or magnetite artifacts have been found at pre-Columbian archaeological sites in Mexico and Guetemala.[6][7]
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Compass Subcategories
Compass Articles
Your Inner Compass by Steven Sadleir
We each have an inner compass guiding us to fulfill our purpose. We all have an inner knowing that is providing the impetus for us to develop ourselves. We are all evolving, all growing more conscious through all our life experiences; all part of a c...
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