1.
Smartphone
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A smartphone is a mobile phone with an advanced mobile operating system that combines features of a personal computer operating system with other features useful for mobile or handheld use. Smartphones can access the Internet and can run a variety of third-party software components and they typically have a color display with a graphical user interface that covers more than 76% of the front surface. In 1999, the Japanese firm NTT DoCoMo released the first smartphones to achieve mass adoption within a country, smartphones became widespread in the late 2000s. Most of those produced from 2012 onward have high-speed mobile broadband 4G LTE, motion sensors, in the third quarter of 2012, one billion smartphones were in use worldwide. Global smartphone sales surpassed the sales figures for regular cell phones in early 2013, devices that combined telephony and computing were first conceptualized by Nikola Tesla in 1909 and Theodore Paraskevakos in 1971 and patented in 1974, and were offered for sale beginning in 1993. Paraskevakos was the first to introduce the concepts of intelligence, data processing and they were installed at Peoples Telephone Company in Leesburg, Alabama and were demonstrated to several telephone companies. The original and historic working models are still in the possession of Paraskevakos, the first mobile phone to incorporate PDA features was a prototype developed by Frank Canova in 1992 while at IBM and demonstrated that year at the COMDEX computer industry trade show. It included PDA features and other mobile applications such as maps, stock reports. A refined version was marketed to consumers in 1994 by BellSouth under the name Simon Personal Communicator, the Simon was the first commercially available device that could be properly referred to as a smartphone, although it was not called that in 1994. The term smart phone appeared in print as early as 1995, in the mid-late 1990s, many mobile phone users carried a separate dedicated PDA device, running early versions of operating systems such as Palm OS, BlackBerry OS or Windows CE/Pocket PC. These operating systems would later evolve into mobile operating systems, in March 1996, Hewlett-Packard released the OmniGo 700LX, a modified HP 200LX palmtop PC that supported a Nokia 2110 phone with ROM-based software to support it. It had a 640×200 resolution CGA compatible four-shade gray-scale LCD screen and could be used to place and receive calls and it was also 100% DOS5.0 compatible, allowing it to run thousands of existing software titles, including early versions of Windows. In August 1996, Nokia released the Nokia 9000 Communicator, a cellular phone based on the Nokia 2110 with an integrated PDA based on the PEN/GEOS3.0 operating system from Geoworks. The two components were attached by a hinge in what known as a clamshell design, with the display above. The PDA provided e-mail, calendar, address book, calculator and notebook applications, text-based Web browsing, when closed, the device could be used as a digital cellular phone. In June 1999 Qualcomm released the pdQ Smartphone, a CDMA digital PCS Smartphone with an integrated Palm PDA, subsequent landmark devices included, The Ericsson R380 by Ericsson Mobile Communications. The first device marketed as a smartphone, it combined the functions of a phone and PDA. The Kyocera 6035 introduced by Palm, Inc, combining a PDA with a mobile phone, it operated on the Verizon network, and supported limited Web browsing
2.
Magnetometer
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A compass is a simple example of a magnetometer, one that measures the direction of an ambient magnetic field. Magnetometers are widely used for measuring the Earths magnetic field and in geophysical surveys to detect anomalies of various types. They are also used in the military to detect submarines, consequently, some countries, such as the United States, Canada and Australia, classify the more sensitive magnetometers as military technology, and control their distribution. Magnetic fields are vector quantities characterized by strength and direction. The strength of a field is measured in units of tesla in the SI units. 10,000 gauss are equal to one tesla, measurements of the Earths magnetic field are often quoted in units of nanotesla, also called a gamma. Gaussmeters and teslameters are magnetometers that measure in units of gauss or tesla, in some contexts, magnetometer is the term used for an instrument that measures fields of less than 1 millitesla and gaussmeter is used for those measuring greater than 1 mT. There are two types of magnetometer measurement. Vector magnetometers measure the components of a magnetic field. Total field magnetometers or scalar magnetometers measure the magnitude of the magnetic field. Magnetometers used to study the Earths magnetic field may express the components of the field in terms of declination. Absolute magnetometers measure the magnitude or vector magnetic field, using an internal calibration or known physical constants of the magnetic sensor. Relative magnetometers measure magnitude or vector magnetic field relative to a fixed but uncalibrated baseline, also called variometers, relative magnetometers are used to measure variations in magnetic field. Magnetometers may also be classified by their situation or intended use, stationary magnetometers are installed to a fixed position and measurements are taken while the magnetometer is stationary. Portable or mobile magnetometers are meant to be used while in motion, laboratory magnetometers are used to measure the magnetic field of materials placed within them and are typically stationary. The performance and capabilities of magnetometers are described through their technical specifications, major specifications include Sample rate is the amount of readings given per second. The inverse is the time in seconds per reading. Sample rate is important in mobile magnetometers, the sample rate, bandwidth or bandpass characterizes how well a magnetometer tracks rapid changes in magnetic field
3.
Navigation
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Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four categories, land navigation, marine navigation, aeronautic navigation. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks, all navigational techniques involve locating the navigators position compared to known locations or patterns. Navigation, in a sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes orienteering and pedestrian navigation, for information about different navigation strategies that people use, visit human navigation. In the European medieval period, navigation was considered part of the set of seven mechanical arts, early Pacific Polynesians used the motion of stars, weather, the position of certain wildlife species, or the size of waves to find the path from one island to another. Maritime navigation using scientific instruments such as the mariners astrolabe first occurred in the Mediterranean during the Middle Ages, the perfecting of this navigation instrument is attributed to Portuguese navigators during early Portuguese discoveries in the Age of Discovery. Open-seas navigation using the astrolabe and the compass started during the Age of Discovery in the 15th century, the Portuguese began systematically exploring the Atlantic coast of Africa from 1418, under the sponsorship of Prince Henry. In 1488 Bartolomeu Dias reached the Indian Ocean by this route, in 1492 the Spanish monarchs funded Christopher Columbuss expedition to sail west to reach the Indies by crossing the Atlantic, which resulted in the Discovery of America. In 1498, a Portuguese expedition commanded by Vasco da Gama reached India by sailing around Africa, soon, the Portuguese sailed further eastward, to the Spice Islands in 1512, landing in China one year later. The fleet of seven ships sailed from Sanlúcar de Barrameda in Southern Spain in 1519, crossed the Atlantic Ocean, some ships were lost, but the remaining fleet continued across the Pacific making a number of discoveries including Guam and the Philippines. By then, only two galleons were left from the original seven, the Victoria led by Elcano sailed across the Indian Ocean and north along the coast of Africa, to finally arrive in Spain in 1522, three years after its departure. The Trinidad sailed east from the Philippines, trying to find a path back to the Americas. He arrived in Acapulco on October 8,1565, the term stems from 1530s, from Latin navigationem, from navigatus, pp. of navigare to sail, sail over, go by sea, steer a ship, from navis ship and the root of agere to drive. Roughly, the latitude of a place on Earth is its angular distance north or south of the equator, latitude is usually expressed in degrees ranging from 0° at the Equator to 90° at the North and South poles. The height of Polaris in degrees above the horizon is the latitude of the observer, similar to latitude, the longitude of a place on Earth is the angular distance east or west of the prime meridian or Greenwich meridian. Longitude is usually expressed in degrees ranging from 0° at the Greenwich meridian to 180° east and west, sydney, for example, has a longitude of about 151° east. New York City has a longitude of 74° west, for most of history, mariners struggled to determine longitude
4.
Cardinal direction
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The four cardinal directions or cardinal points are the directions of north, east, south, and west, commonly denoted by their initials, N, E, S, W. East and west are at angles to north and south, with east being in the clockwise direction of rotation from north. Intermediate points between the four cardinal directions form the points of the compass, the intermediate directions are northeast, southeast, southwest, and northwest. To keep to a bearing is not, in general, the same as going in a straight direction along a great circle, conversely, one can keep to a great circle and the bearing may change. Thus the bearing of a path crossing the North Pole changes abruptly at the Pole from North to South. When traveling East or West, it is only on the Equator that one can keep East or West, anywhere else, maintaining latitude requires a change in direction, requires steering. However, this change in direction becomes increasingly negligible as one moves to lower latitudes, the Earth has a magnetic field which is approximately aligned with its axis of rotation. A magnetic compass is a device uses this field to determine the cardinal directions. Magnetic compasses are used, but only moderately accurate. The position of the Sun in the sky can be used for orientation if the time of day is known. In the morning the Sun rises roughly in the east and tracks upwards, in the evening it sets in the west, again roughly and only due west exactly on the equinoxes. This method does not work well when closer to the equator since, in the northern hemisphere. Conversely, at low latitudes in the hemisphere the sun may be to the south of the observer in summer. If they move clockwise, the sun will be in the south at midday, because of the Earths axial tilt, no matter what the location of the viewer, there are only two days each year when the sun rises precisely due east. On all other days, depending on the time of year, for all locations the sun is seen to rise north of east from the Northward equinox to the Southward equinox, and rise south of east from the Southward equinox to the Northward equinox. There is a method by which an analog watch can be used to locate north and south. The Sun appears to move in the sky over a 24-hour period while the hand of a 12-hour clock face takes twelve hours to complete one rotation. In the northern hemisphere, if the watch is rotated so that the hand points toward the Sun
5.
Compass rose
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It is also the term for the graduated markings found on the traditional magnetic compass. The modern compass rose has eight principal winds, 8-point compass roses us the eight principal winds—that is, the four cardinal directions plus the four intercardinal or ordinal directions, at angles of difference of 45°. 16-point compass roses are constructed by bisecting the angles of the winds to come up with intermediate compass points, known as half-winds. The names of the half-winds are simply combinations of the winds to either side. 32-point compass roses are constructed by bisecting these angles, and coming up with quarter-winds at 11 1⁄4° angles of difference, north-by-east is one quarter wind from North towards East, Northeast-by-north is one quarter wind from Northeast toward North. Naming all 32 points on the rose is called boxing the compass, the 32-point rose has the uncomfortable number of 11 1⁄4° between points, but is easily found by halving divisions and may have been easier for those not using a 360° circle. Using gradians, of which there are 400 in a circle, linguistic anthropological studies have shown that most human communities have four points of cardinal direction. The names given to these directions are usually derived from either locally-specific geographic features or from celestial bodies or from atmospheric features, most mobile populations tend to adopt sunrise and sunset for East and West and the direction from where different winds blow to denote North and South. The ancient Greeks originally maintained distinct and separate systems of points, the four Greek cardinal points were based on celestial bodies and used for orientation. The four Greek winds were confined to meteorology, nonetheless, both systems were gradually conflated, and wind names came to eventually denote cardinal directions as well. To restore balance, Timosthenes of Rhodes added two more winds to produce the classical 12-wind rose, and began using the winds to denote geographical direction in navigation, eratosthenes deducted two winds from Aristotles system, to produce the classical 8-wind rose. The Romans adopted the Greek 12-wind system, and replaced its names with Latin equivalents, e. g. Septentrio, Subsolanus, Auster, Favonius, uniquely, Vitruvius came up with a 24-wind rose. According to the chronicler Einhard, the Frankish king Charlemagne himself came up with his own names for the classical 12 winds and he named the four cardinal winds on the roots Nord, Ost, Sund and Vuest. Intermediate winds were constructed as simple compound names of these four and these Carolingian names are the source of the modern compass point names found in nearly all modern west European languages. The following table gives an equivalence of the classical 12-wind rose with the modern compass directions. The sidereal compass rose demarcates the compass points by the position of stars in the night sky, arab navigators in the Red Sea and the Indian Ocean, who depended on celestial navigation, were using a 32-point sidereal compass rose before the end of the 10th century. The other thirty points on the rose were determined by the rising and setting positions of fifteen bright stars. Reading from North to South, in their rising and setting positions, the true position of these stars is only approximate to their theoretical equidistant rhumbs on the sidereal compass
6.
North
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North is one of the four cardinal directions or compass points. It is the opposite of south and is perpendicular to east and west, North is a noun, adjective, or adverb indicating direction or geography. The word north is related to the Old High German nord, the Latin word borealis comes from the Greek boreas north wind, north, which, according to Ovid, was personified as the son of the river-god Strymon, the father of Calais and Zetes. Septentrionalis is from septentriones, the seven plow oxen, a name of Ursa Maior, the Greek ἀρκτικός is named for the same constellation, and is the source of the English word Arctic. For example, in Lezgian, kefer can mean both disbelief and north, since to the north of the Muslim Lezgian homeland there are areas formerly inhabited by non-Muslim Caucasian, in many languages of Mesoamerica, north also means up. The direction north is associated with colder climates because most of the worlds land at high latitudes is located in the Northern Hemisphere. By convention, the top side of a map is often north, to go north using a compass for navigation, set a bearing or azimuth of 0° or 360°. North is specifically the direction that, in Western culture, is treated as the fundamental direction, on any rotating non-astronomical object, north denotes the side appearing to rotate counter-clockwise when viewed from afar along the axis of rotation. Magnetic north is of interest because it is the direction indicated as north on a properly functioning magnetic compass, the difference between it and true north is called the magnetic declination. But simple generalizations on the subject should be treated as unsound, maps intended for usage in orienteering by compass will clearly indicate the local declination for easy correction to true north. Maps may also indicate grid north, which is a term referring to the direction northwards along the grid lines of a map projection. The visible rotation of the sky around the visible celestial pole provides a vivid metaphor of that direction corresponding to up. Thus the choice of the north as corresponding to up in the hemisphere, or of south in that role in the southern, is, prior to worldwide communication, anything. On the contrary, it is of interest that Chinese and Islamic culture even considered south as the top end for maps. Up is a metaphor for north, the notion that north should always be up and east at the right was established by the Greek astronomer Ptolemy. While the choice of north over south as prime direction reflects quite arbitrary historical factors and their folk definitions are, respectively, where the sun rises and where it sets. The true folk-astronomical definitions of east and west are the directions, an angle from the prime direction. Being the default direction on the compass, north is referred to frequently in Western popular culture, some examples include, The phrase north of X is often used by Americans to mean more than X or greater than X, i. e
7.
South
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South is a noun, adjective, or adverb indicating direction or geography. It is one of the four directions or compass points. South is the polar opposite of north and is perpendicular to east and west, the word south comes from Old English sūþ, from earlier Proto-Germanic *sunþaz, possibly related to the same Proto-Indo-European root that the word sun derived from. By convention, the side of a map is south. To go south using a compass for navigation, set a bearing or azimuth of 180°, alternatively, in the Northern Hemisphere outside the tropics, the Sun will be roughly in the south at midday. True south is the direction towards the end of the axis about which the earth rotates. The South Pole is located in Antarctica, magnetic south is the direction towards the south magnetic pole, some distance away from the south geographic pole. Roald Amundsen, from Norway, was the first to reach the South Pole, on 14 December 1911, the Global South refers to the socially and economically less-developed southern half of the globe. 95% of the Global North has enough food and shelter, in the South, on the other hand, only 5% of the population has enough food and shelter. It lacks appropriate technology, it has no political stability, the economies are disarticulated, in the card game bridge, one of the players is known for scoring purposes as South. South partners with North and plays against East and West, in Greek religion, Notos, was the south wind and bringer of the storms of late summer and autumn. The dictionary definition of south at Wiktionary
8.
East
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East is one of the four cardinal directions or points of the compass. It is the direction from west. This is similar to Old High German *ōstar to the east, Latin aurora dawn, Ēostre, a Germanic goddess of dawn, might have been a personification of both dawn and the cardinal points. By convention, the hand side of a map is east. This convention has developed from the use of a compass, which places north at the top, to go east using a compass for navigation, one sets a bearing or azimuth of 90°. East is the direction toward which the Earth rotates about its axis, the practice of praying towards the East is older than Christianity, but has been adopted by this religion as the Orient was thought of as containing mankinds original home. Hence, some Christian churches have been oriented towards the east. Easting Oriental The dictionary definition of east at Wiktionary
9.
West
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West is one of the four cardinal directions or points of the compass. It is the direction from east. The word West is a Germanic word passed into some Romance languages, as is apparent in the Gothic term vasi, it stems from the same Indo-European root that gave the Sanskrit vas-ati and vesper in Latin. To go west using a compass for navigation, one needs to set a bearing or azimuth of 270°, West is the direction opposite that of the Earths rotation on its axis, and is therefore the general direction towards which the Sun appears to constantly progress and eventually set. Moving continuously west is following a circle of latitude, the phrase the West is often spoken in reference to the Western world, which includes the European Union, the Americas, Israel, Australia, New Zealand and South Africa. The concept of the Western part of the earth has its roots in the Western Roman Empire, during the Cold War the West was often used to refer to the NATO camp as opposed to the Warsaw Pact and non-aligned nations. The expression survives, with an ambiguous meaning. In Chinese Buddhism, the West represents movement toward the Buddha or enlightenment, the ancient Aztecs believed that the West was the realm of the great goddess of water, mist, and maize. In Ancient Egypt, the West was considered to be the portal to the netherworld, Ancient Egyptians also believed that the Goddess Amunet was a personification of the West. The Celts believed that beyond the sea off the edges of all maps lay the Otherworld. According to the Bible, the Israelites crossed the Jordan River westward into the Promised Land, in Islam, while in India, people pray facing towards the west as in respect to India, Mecca is in the West-ward direction. In American literature moving West has sometimes symbolized gaining freedom, perhaps as an association with the settling of the Old West, the dictionary definition of west at Wiktionary
10.
Clockwise
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Rotation can occur in two possible directions. A clockwise motion is one that proceeds in the direction as a clocks hands, from the top to the right, then down and then to the left. The opposite sense of rotation or revolution is counterclockwise or anticlockwise, in a mathematical sense, a circle defined parametrically in a positive Cartesian plane by the equations x = cos t and y = sin t is traced counterclockwise as t increases in value. Before clocks were commonplace, the terms sunwise and deasil, deiseil and even deocil from the Scottish Gaelic language, widdershins or withershins was used for counterclockwise. The terms clockwise and counterclockwise can only be applied to a rotational motion once a side of the plane is specified. For example, the rotation of the Earth is clockwise when viewed from above the South Pole. Clocks traditionally follow this sense of rotation because of the clocks predecessor, clocks with hands were first built in the Northern Hemisphere, and they were made to work like sundials. In order for a sundial to work, it must be placed looking northward. Then, when the Sun moves in the sky, the shadow cast on the side of the sundial moves with the same sense of rotation. This is why hours were drawn in sundials in that manner, note, however, that on a vertical sundial, the shadow moves in the opposite direction, and some clocks were constructed to mimic this. The best-known surviving example is the clock in the Münster Cathedral. Occasionally, clocks whose hands revolve counterclockwise are nowadays sold as a novelty, historically, some Jewish clocks were built that way, for example in some synagogue towers in Europe, to accord with right-to-left reading in the Hebrew language. In 2014 under Bolivian president Evo Morales, the clock outside the Legislative Assembly in Plaza Murillo, typical nuts, screws, bolts, bottle caps, and jar lids are tightened clockwise and loosened counterclockwise in accordance with the right-hand rule. Almost all threaded objects obey this rule except for a few left-handed exceptions described below, sometimes the opposite sense of threading is used for a special reason. A thread might need to be left-handed to prevent operational stresses from loosening it, for bicycle pedals, the one on the left must be reverse-threaded to prevent it unscrewing during use. Similarly, the whorl of a spinning wheel uses a left-hand thread to keep it from loosening. A turnbuckle has right-handed threads on one end and left-handed threads on the other, in trigonometry and mathematics in general, plane angles are conventionally measured counterclockwise, starting with 0° or 0 radians pointing directly to the right, and 90° pointing straight up. However, in navigation, compass headings increase clockwise around the face, starting with 0° at the top of the compass
11.
Azimuth
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An azimuth is an angular measurement in a spherical coordinate system. An example is the position of a star in the sky, the star is the point of interest, the reference plane is the horizon or the surface of the sea, and the reference vector points north. The azimuth is the angle between the vector and the perpendicular projection of the star down onto the horizon. Azimuth is usually measured in degrees, the concept is used in navigation, astronomy, engineering, mapping, mining and artillery. In land navigation, azimuth is usually denoted alpha, α, azimuth has also been more generally defined as a horizontal angle measured clockwise from any fixed reference plane or easily established base direction line. Today, the plane for an azimuth is typically true north, measured as a 0° azimuth. Moving clockwise on a 360 degree circle, east has azimuth 90°, south 180°, there are exceptions, some navigation systems use south as the reference vector. Any direction can be the vector, as long as it is clearly defined. Quite commonly, azimuths or compass bearings are stated in a system in which either north or south can be the zero, the reference direction, stated first, is always north or south, and the turning direction, stated last, is east or west. The directions are chosen so that the angle, stated between them, is positive, between zero and 90 degrees. If the bearing happens to be exactly in the direction of one of the cardinal points and this is the reason why the X and Y axis in the above formula are swapped. If the azimuth becomes negative, one can always add 360°, the formula in radians would be slightly easier, α = atan2 Caveat, Most computer libraries reverse the order of the atan2 parameters. We are standing at latitude φ1, longitude zero, we want to find the azimuth from our viewpoint to Point 2 at latitude φ2, longitude L. The difference is usually small, if Point 2 is not more than 100 km away. Various websites will calculate geodetic azimuth, e. g. GeoScience Australia site, formulas for calculating geodetic azimuth are linked in the distance article. Normal-section azimuth is simpler to calculate, Bomford says Cunninghams formula is exact for any distance, replace φ2 with declination and longitude difference with hour angle, and change the sign. There is a variety of azimuthal map projections. They all have the property that directions from a point are preserved
12.
Bearing (navigation)
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Absolute bearing refers to the angle between the magnetic North or true North and an object. For example, an object to the East would have a bearing of 90 degrees. Relative bearing refers to the angle between the forward direction, and the location of another object. For example, a relative bearing of 0 degrees would be dead ahead. Bearings can be measured in mils or degrees, the bearing consists of 2 characters and 1 number, first, the character is either N or S. Third, the representing the direction of the angle away from the reference ray - thus, either E. The angle value will always be less than 90 degrees, for example, if Point B is located exactly southeast of Point A, the bearing from Point A to Point B is S 45° E. The US Army defines the azimuth between Point A and Point B as the angle, measured in the direction, between the north reference ray and Ray AB. For example, if the bearing between Point A and Point B is S 45° E, the azimuth between Point A and Point B is 135°, the angle value in a bearing can be specified in the units of degrees, mils, or grad. An azimuth is specified in the same angle units, a bearing can be taken on another vessel to aid piloting. A bearing can be taken to a fixed or moving object in order to target it with gunfire or missiles and this is mainly used by ground troops when using an air-strike on the target. A bearing can be taken to a person or vessel in distress in order to go to their aid or, the latter is not the same as the direction toward the magnetic north pole due to magnetic anomalies. It should be close to the magnetic bearing.9 degrees. Measured in this way, a bearing is referred to as an azimuth by the US Army but not by armies in other English speaking nations, if the reference direction is north, the bearing is termed an absolute bearing. In a contemporary land navigation context, true, magnetic, and grid bearings are measured in this way, with true north, magnetic north. In aircraft navigation, an angle is measured from the aircrafts track or heading. If the aircraft encounters a target that is not ahead of the aircraft and not on an identical track, in marine navigation, starboard bearings are green and port bearings are red. Thus, in navigation, a target directly off the starboard side would be Green090 or G090
13.
Four Great Inventions
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The Four Great Inventions are inventions from ancient China that are celebrated in Chinese culture for their historical significance and as symbols of ancient Chinas advanced science and technology. The Four Great Inventions are, Compass Gunpowder Papermaking Printing These four discoveries had a impact on the development of civilization throughout the world. This commonplace spread rapidly throughout Europe in the 16th century and was appropriated only in recent times by Chinese scholars and these inventions were a badge of honor to modern Europeans, who proclaimed that there was nothing to equal them among the ancient Greeks and Romans. After reports by Portuguese sailors and Spanish missionaries began to back to Europe beginning in the 1530s. By 1620, when Francis Bacon wrote in his Instauratio magna that printing, gunpowder, and the nautical compass. Have altered the face and state of the world, first, in matters, second, in warfare, third, in navigation. Western writers and scholars from the 19th century onwards commonly attributed these inventions to China, edkins notes on these inventions were mentioned in an 1859 review in the journal Athenaeum, comparing the contemporary science and technology in China and Japan. In 1880 Johnsons New Universal Cyclopædia, A Scientific and Popular Treasury of Useful Knowledge. The Chautauquan in 1887, none of these, however, referred to four inventions or called them great. A lodestone compass was used in China during the Han Dynasty between the 2nd century BC and 1st century AD, where it was called the south-governor and it was not used for navigation, but rather for geomancy and fortune-telling. The device is recommended as a means of orientation in the obscurity of the night, the first suspended magnetic needle compass was written of by Shen Kuo in his book of 1088. For most of Chinese history, the compass that remained in use was in the form of a magnetic needle floating in a bowl of water. According to Needham, the Chinese in the Song Dynasty and continuing Yuan Dynasty did make use of a dry compass, Gunpowder was discovered in the 9th century by Chinese alchemists searching for an elixir of immortality. By that time, the Chinese had discovered how to create explosive round shot by packing their hollow shells with this nitrate-enhanced gunpowder, however, a recent archaeological discovery has been reported from Gansu of paper with Chinese characters on it dating to 8 BC. While paper used for wrapping and padding was used in China since the 2nd century BC, by the 6th century in China, sheets of paper were beginning to be used for toilet paper as well. During the Tang Dynasty paper was folded and sewn into square bags to preserve the flavor of tea, the Song Dynasty that followed was the first government to issue paper currency. The Chinese invention of Woodblock printing, at some point before the first dated book in 868, according to A. Hyatt Mayor, curator at the Metropolitan Museum of Art, it was the Chinese who really discovered the means of communication that was to dominate until our age. Woodblock printing was better suited to Chinese characters than movable type, which the Chinese also invented, western printing presses, although introduced in the 16th century, were not widely used in China until the 19th century. China, along with Korea, was one of the last countries to adopt them, Woodblock printing for textiles, on the other hand, preceded text printing by centuries in all cultures, and is first found in China at around 220
14.
Divination
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Divination is the attempt to gain insight into a question or situation by way of an occultic, standardized process or ritual. Divination can be seen as a method with which to organize what appear to be disjointed. Fortune-telling, on the hand, is a more everyday practice for personal purposes. Particular divination methods vary by culture and religion, divination is dismissed by the scientific community and skeptics as being superstition. Psychologist Julian Jaynes categorized divination into the four types, Omens. Chinese history offers scrupulously documented occurrences of births, the tracking of natural phenomena. Chinese governmental planning relied on this method of forecasting for long-range strategies and it is not unreasonable to assume that modern scientific inquiry began with this kind of divination, Joseph Needhams work considered this very idea. This consists of the casting of lots, or sortes, whether with sticks, stones, bones, beans, coins, modern playing cards and board games developed from this type of divination. This ranks a set of given possibilities and it can be qualitative, for example, dowsing developed from this type of divination. The Romans, in times, used Etruscan methods of augury such as hepatoscopy. Augury is normally considered to refer to divination by studying the flight patterns of birds. An unconstrained form of divination, free from any particular medium, the answer comes from whatever object the diviner happens to see or hear. Some religions use a form of bibliomancy, they ask a question, riffle the pages of their holy book, other forms of spontaneous divination include reading auras and New Age methods of feng shui such as intuitive and fuzion. In this practice, the examines the hands of a person for whom they are divining for indications of their future. The Oracle of Amun at the Siwa Oasis was made famous when Alexander the Great visited it after delivering Egypt from Persian rule in 332 BC, deuteronomy 18, 10-12 or Leviticus 19,26 can be interpreted as categorically forbidding divination. However, some would claim that divination is indeed practiced in the Bible, such as in Exodus 28, communicating with God through prayer is not the same as divination, though both are open, typically two-way conversations with God. Both oracles and seers in ancient Greece practiced divination, oracles were the conduits for the gods on earth, their prophecies were understood to be the will of the gods verbatim. Because of the demand for oracle consultations and the oracles’ limited work schedule
15.
History of science and technology in China
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Among the earliest inventions were the abacus, the shadow clock, and the first items such as Kongming lanterns. The Tang Dynasty in particular, was a time of great innovation, a good deal of exchange occurred between Western and Chinese discoveries up to the Qing Dynasty. In the 19th and 20th century the introduction of Western technology was a factor in the modernization of China. Much of the early Western work in the history of science in China was done by Joseph Needham, the Warring States period began 2500 years ago at the time of the invention of the crossbow. Needham notes that the invention of the crossbow far outstripped the progress in defensive armor, at this time, there were also many nascent schools of thought in China — the Hundred Schools of Thought, scattered among many polities. The schools served as communities which advised the rulers of these states, mo Di introduced concepts useful to one of those rulers, such as defensive fortification. One of these concepts, fa was extended by the School of Names, the development of a school of logic was cut short by the defeat of Mohisms political sponsors by the Qin Dynasty, and the subsumption of fa as law rather than method by the Legalists. You conquered the empire on horseback, but from horseback you will never succeed in ruling it, derived from Taoist philosophy, one of the newest longstanding contributions of the ancient Chinese are in Traditional Chinese medicine, including acupuncture and herbal medicine. These claims, however, are disputed and rely on much supposition. The Book of Silk was the first definitive atlas of comets and it listed 29 comets that appeared over a period of about 300 years, with renderings of comets describing an event its appearance corresponded to. In architecture, the pinnacle of Chinese technology manifested itself in the Great Wall of China, typical Chinese architecture changed little from the succeeding Han Dynasty until the 19th century. The Qin Dynasty also developed the crossbow, which became the mainstream weapon in Europe. Several remains of crossbows have been found among the soldiers of the Terracotta Army in the tomb of Qin Shi Huang, the Eastern Han Dynasty scholar and astronomer Zhang Heng invented the first water-powered rotating armillary sphere, and catalogued 2500 stars and over 100 constellations. In 132, he invented the first seismological detector, called the Houfeng Didong Yi, according to the History of Later Han Dynasty, this seismograph was an urn-like instrument, which would drop one of eight balls to indicate when and in which direction an earthquake had occurred. On June 13,2005, Chinese seismologists announced that they had created a replica of the instrument, the mechanical engineer Ma Jun was another impressive figure from ancient China. However, Ma Juns most impressive invention was the south-pointing chariot and it incorporated the use of a differential gear in order to apply equal amount of torque to wheels rotating at different speeds, a device that is found in all modern automobiles. Sliding calipers were invented in China almost 2,000 years ago, the Chinese civilization was the earliest civilization to experiment successfully with aviation, with the kite and Kongming lantern being the first flying machines. The Four Great Inventions are the compass, gunpowder, papermaking and printing, paper and printing were developed first
16.
Han dynasty
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The Han dynasty was the second imperial dynasty of China, preceded by the Qin dynasty and succeeded by the Three Kingdoms period. Spanning over four centuries, the Han period is considered an age in Chinese history. To this day, Chinas majority ethnic group refers to itself as the Han people and it was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han, and briefly interrupted by the Xin dynasty of the former regent Wang Mang. This interregnum separates the Han dynasty into two periods, the Western Han or Former Han and the Eastern Han or Later Han, the emperor was at the pinnacle of Han society. He presided over the Han government but shared power with both the nobility and appointed ministers who came largely from the gentry class. The Han Empire was divided into areas controlled by the central government using an innovation inherited from the Qin known as commanderies. These kingdoms gradually lost all vestiges of their independence, particularly following the Rebellion of the Seven States, from the reign of Emperor Wu onward, the Chinese court officially sponsored Confucianism in education and court politics, synthesized with the cosmology of later scholars such as Dong Zhongshu. This policy endured until the fall of the Qing dynasty in 1911 AD, the Han dynasty was an age of economic prosperity and saw a significant growth of the money economy first established during the Zhou dynasty. The coinage issued by the government mint in 119 BC remained the standard coinage of China until the Tang dynasty. The period saw a number of limited institutional innovations, the Xiongnu, a nomadic steppe confederation, defeated the Han in 200 BC and forced the Han to submit as a de facto inferior partner, but continued their raids on the Han borders. Emperor Wu of Han launched several campaigns against them. The ultimate Han victory in these wars eventually forced the Xiongnu to accept vassal status as Han tributaries, the territories north of Hans borders were quickly overrun by the nomadic Xianbei confederation. Imperial authority was seriously challenged by large Daoist religious societies which instigated the Yellow Turban Rebellion. When Cao Pi, King of Wei, usurped the throne from Emperor Xian, following Liu Bangs victory in the Chu–Han Contention, the resulting Han dynasty was named after the Hanzhong fief. Chinas first imperial dynasty was the Qin dynasty, the Qin unified the Chinese Warring States by conquest, but their empire became unstable after the death of the first emperor Qin Shi Huangdi. Within four years, the authority had collapsed in the face of rebellion. Although Xiang Yu proved to be a commander, Liu Bang defeated him at Battle of Gaixia. Liu Bang assumed the title emperor at the urging of his followers and is known posthumously as Emperor Gaozu, Changan was chosen as the new capital of the reunified empire under Han
17.
Song dynasty
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The Song dynasty was an era of Chinese history that began in 960 and continued until 1279. It succeeded the Five Dynasties and Ten Kingdoms period, coincided with the Liao and Western Xia dynasties and it was the first government in world history to issue banknotes or true paper money nationally and the first Chinese government to establish a permanent standing navy. This dynasty also saw the first known use of gunpowder, as well as the first discernment of true north using a compass, the Song dynasty is divided into two distinct periods, Northern and Southern. During the Northern Song, the Song capital was in the city of Bianjing. The Southern Song refers to the period after the Song lost control of its half to the Jurchen Jin dynasty in the Jin–Song Wars. During this time, the Song court retreated south of the Yangtze, the Southern Song dynasty considerably bolstered its naval strength to defend its waters and land borders and to conduct maritime missions abroad. To repel the Jin, and later the Mongols, the Song developed revolutionary new military technology augmented by the use of gunpowder, in 1234, the Jin dynasty was conquered by the Mongols, who took control of northern China, maintaining uneasy relations with the Southern Song. Möngke Khan, the fourth Great Khan of the Mongol Empire and his younger brother Kublai Khan was proclaimed the new Great Khan, though his claim was only partially recognized by the Mongols in the west. In 1271, Kublai Khan was proclaimed the Emperor of China, after two decades of sporadic warfare, Kublai Khans armies conquered the Song dynasty in 1279. The Mongol invasion led to a reunification under the Yuan dynasty, the population of China doubled in size during the 10th and 11th centuries. The Northern Song census recorded a population of roughly 50 million, much like the Han and this data is found in the Standard Histories. However, it is estimated that the Northern Song had a population of some 100 million people and this dramatic increase of population fomented an economic revolution in pre-modern China. The expansion of the population, growth of cities, and the emergence of a national economy led to the withdrawal of the central government from direct involvement in economic affairs. The lower gentry assumed a role in grassroots administration and local affairs. Appointed officials in county and provincial centers relied upon the gentry for their services, sponsorship. Social life during the Song was vibrant, citizens gathered to view and trade precious artworks, the populace intermingled at public festivals and private clubs, and cities had lively entertainment quarters. The spread of literature and knowledge was enhanced by the expansion of woodblock printing. Technology, science, philosophy, mathematics, and engineering flourished over the course of the Song, although the institution of the civil service examinations had existed since the Sui dynasty, it became much more prominent in the Song period
18.
Western Europe
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Western Europe, or West Europe, is the region comprising the western part of Europe. Below, some different geographic and geopolitical definitions of the term are outlined, prior to the Roman conquest, a large part of Western Europe had adopted the newly developed La Tène culture. This cultural and linguistic division was reinforced by the later political east-west division of the Roman Empire. The division between these two was enhanced during Late Antiquity and the Middle Ages by a number of events, the Western Roman Empire collapsed, starting the Early Middle Ages. By contrast, the Eastern Roman Empire, mostly known as the Greek or Byzantine Empire, survived, in East Asia, Western Europe was historically known as taixi in China and taisei in Japan, which literally translates as the Far West. The term Far West became synonymous with Western Europe in China during the Ming dynasty, the Italian Jesuit priest Matteo Ricci was one of the first writers in China to use the Far West as an Asian counterpart to the European concept of the Far East. In his writings, Ricci referred to himself as Matteo of the Far West, the term was still in use in the late 19th and early 20th centuries. Post-war Europe would be divided into two spheres, the West, influenced by the United States, and the Eastern Bloc. With the onset of the Cold War, Europe was divided by the Iron Curtain, behind that line lie all the capitals of the ancient states of Central and Eastern Europe. Although some countries were neutral, they were classified according to the nature of their political. This division largely defined the popular perception and understanding of Western Europe, the world changed dramatically with the fall of the Iron Curtain in 1989. The Federal Republic of Germany peacefully absorbed the German Democratic Republic, COMECON and the Warsaw Pact were dissolved, and in 1991, the Soviet Union ceased to exist. Several countries which had part of the Soviet Union regained full independence. Although the term Western Europe was more prominent during the Cold War, it remains much in use, in 1948 the Treaty of Brussels was signed between Belgium, France, Luxembourg, the Netherlands and the United Kingdom. It was further revisited in 1954 at the Paris Conference, when the Western European Union was established and it was declared defunct in 2011, after the Treaty of Lisbon, and the Treaty of Brussels was terminated. When the Western European Union was dissolved, it had 10 member countries, six member countries, five observer countries. The CIA divides Western Europe into two smaller subregions, regional voting blocs were formed in 1961 to encourage voting to various UN bodies from different regional groups. The European Union is an economic and political union of 28 member states that are located primarily in Europe, some Western and Northern European countries of Iceland, Norway, Switzerland and Liechtenstein are members of EFTA, though cooperating to varying degree with the European Union
19.
Muslim world
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The terms Muslim world and Islamic world commonly refer to the Islamic community, comprising all those who adhere to the religion of Islam, or to societies where Islam is practiced. In a modern sense, these terms refer to countries where Islam is widespread. In the modern era, most of the Muslim world came under influence or colonial domination of European powers. The nation states emerged in the post-colonial era have adopted a variety of political and economic models. As of 2015, over 1.7 billion or about 23. 4% of the population are Muslims including the 4. 4% who live as minorities. Muslim history involves the history of the Islamic faith as a religion, the history of Islam began in Arabia with the Islamic prophet Muhammads first recitations of the Quran in the 7th century in the month of Ramadan. However, Islam under the Rashidun Caliphate grew rapidly, a century after the death of last Islamic prophet Muhammad, the Islamic empire extended from Spain in the west to Indus in the east. The Islamic Golden Age coincided with the Middle Ages in the Muslim world, starting with the rise of Islam and establishment of the first Islamic state in 622. The end of the age is given as 1258 with the Mongolian Sack of Baghdad, or 1492 with the completion of the Christian Reconquista of the Emirate of Granada in Al-Andalus. The Abbasids were influenced by the Quranic injunctions and hadiths, such as the ink of a scholar is more holy than the blood of a martyr, that stressed the value of knowledge. The major Islamic capital cities of Baghdad, Cairo, and Córdoba became the intellectual centers for science, philosophy, medicine. Between the 8th and 18th centuries, the use of glaze was prevalent in Islamic art. Tin-opacified glazing was one of the earliest new technologies developed by the Islamic potters, the first Islamic opaque glazes can be found as blue-painted ware in Basra, dating to around the 8th century. Another contribution was the development of fritware, originating from 9th century Iraq, other centers for innovative ceramic pottery in the Old world included Fustat, Damascus and Tabriz. The original concept is derived from a pre-Islamic Persian prototype Hezār Afsān that relied on particular Indian elements and it reached its final form by the 14th century, the number and type of tales have varied from one manuscript to another. All Arabian fantasy tales tend to be called Arabian Nights stories when translated into English, regardless of whether they appear in The Book of One Thousand and this work has been very influential in the West since it was translated in the 18th century, first by Antoine Galland. Imitations were written, especially in France, various characters from this epic have themselves become cultural icons in Western culture, such as Aladdin, Sinbad the Sailor and Ali Baba. A famous example of Arabic poetry and Persian poetry on romance is Layla and Majnun and it is a tragic story of undying love much like the later Romeo and Juliet, which was itself said to have been inspired by a Latin version of Layla and Majnun to an extent
20.
World War I
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World War I, also known as the First World War, the Great War, or the War to End All Wars, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. More than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history and it was one of the deadliest conflicts in history, and paved the way for major political changes, including revolutions in many of the nations involved. The war drew in all the worlds great powers, assembled in two opposing alliances, the Allies versus the Central Powers of Germany and Austria-Hungary. These alliances were reorganised and expanded as more nations entered the war, Italy, Japan, the trigger for the war was the assassination of Archduke Franz Ferdinand of Austria, heir to the throne of Austria-Hungary, by Yugoslav nationalist Gavrilo Princip in Sarajevo on 28 June 1914. This set off a crisis when Austria-Hungary delivered an ultimatum to the Kingdom of Serbia. Within weeks, the powers were at war and the conflict soon spread around the world. On 25 July Russia began mobilisation and on 28 July, the Austro-Hungarians declared war on Serbia, Germany presented an ultimatum to Russia to demobilise, and when this was refused, declared war on Russia on 1 August. Germany then invaded neutral Belgium and Luxembourg before moving towards France, after the German march on Paris was halted, what became known as the Western Front settled into a battle of attrition, with a trench line that changed little until 1917. On the Eastern Front, the Russian army was successful against the Austro-Hungarians, in November 1914, the Ottoman Empire joined the Central Powers, opening fronts in the Caucasus, Mesopotamia and the Sinai. In 1915, Italy joined the Allies and Bulgaria joined the Central Powers, Romania joined the Allies in 1916, after a stunning German offensive along the Western Front in the spring of 1918, the Allies rallied and drove back the Germans in a series of successful offensives. By the end of the war or soon after, the German Empire, Russian Empire, Austro-Hungarian Empire, national borders were redrawn, with several independent nations restored or created, and Germanys colonies were parceled out among the victors. During the Paris Peace Conference of 1919, the Big Four imposed their terms in a series of treaties, the League of Nations was formed with the aim of preventing any repetition of such a conflict. This effort failed, and economic depression, renewed nationalism, weakened successor states, and feelings of humiliation eventually contributed to World War II. From the time of its start until the approach of World War II, at the time, it was also sometimes called the war to end war or the war to end all wars due to its then-unparalleled scale and devastation. In Canada, Macleans magazine in October 1914 wrote, Some wars name themselves, during the interwar period, the war was most often called the World War and the Great War in English-speaking countries. Will become the first world war in the sense of the word. These began in 1815, with the Holy Alliance between Prussia, Russia, and Austria, when Germany was united in 1871, Prussia became part of the new German nation. Soon after, in October 1873, German Chancellor Otto von Bismarck negotiated the League of the Three Emperors between the monarchs of Austria-Hungary, Russia and Germany
21.
Magnetic declination
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Magnetic declination or variation is the angle on the horizontal plane between magnetic north and true north. This angle varies depending on position on the Earths surface, and changes over time. The angle between magnetic and grid meridians is called grid magnetic angle, grid variation, or grivation. ”By convention, declination is positive when magnetic north is east of true north, and negative when it is to the west. Isogonic lines are lines on the Earths surface along which the declination has the constant value. The lowercase Greek letter δ is frequently used as the symbol for magnetic declination, Magnetic declination varies both from place to place and with the passage of time. As a traveller cruises the east coast of the United States, for example, the declination at London, UK is one degree 7 minutes west, and as the country is quite small that figure is fairly good for the whole of the country. It is reducing, and scientists predict that in about 2050 it will be zero, similarly, secular changes to these flows result in slow changes to the field strength and direction at the same point on the Earth. The magnetic declination in an area may change slowly over time, possibly as little as 2–2.5 degrees every hundred years or so. For a location closer to the pole like Ivujivik, the declination may change by 1 degree every three years and this may be insignificant to most travellers, but can be important if using magnetic bearings from old charts or metes in old deeds for locating places with any precision. As an example of how variation changes over time, see the two charts of the area, below, surveyed 124 years apart. The 1884 chart shows a variation of 8 degrees,20 minutes West, the 2008 chart shows 13 degrees,15 minutes West. The instrument used to perform this measurement is known as a declinometer, the approximate position of the north celestial pole is indicated by Polaris. In the northern hemisphere, declination can therefore be determined as the difference between the magnetic bearing and a visual bearing on Polaris. Polaris currently traces a circle 0. 75° in radius around the celestial pole. At high latitudes a plumb-bob is helpful to sight Polaris against an object close to the horizon. A rough estimate of the local declination can be determined from a general isogonic chart of the world or a continent, isogonic lines are also shown on aeronautical and nautical charts. Larger-scale local maps may indicate current local declination, often with the aid of a schematic diagram, unless the area depicted is very small, declination may vary measurably over the extent of the map, so the data may be referred to a specific location on the map. The current rate and direction of change may also be shown, the same diagram may show the angle of grid north, which may differ from true north
22.
Magnetism
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Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the moments of elementary particles give rise to a magnetic field. The most familiar effects occur in materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets. Only a few substances are ferromagnetic, the most common ones are iron, nickel and cobalt, the prefix ferro- refers to iron, because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4. The magnetic state of a material depends on temperature and other such as pressure. A material may exhibit more than one form of magnetism as these variables change, magnetism was first discovered in the ancient world, when people noticed that lodestones, naturally magnetized pieces of the mineral magnetite, could attract iron. The word magnet comes from the Greek term for lodestone, magnítis líthos, in ancient Greece, Aristotle attributed the first of what could be called a scientific discussion of magnetism to the philosopher Thales of Miletus, who lived from about 625 BC to about 545 BC. Around the same time, in ancient India, the Indian surgeon Sushruta was the first to use of the magnet for surgical purposes. In ancient China, the earliest literary reference to magnetism lies in a 4th-century BC book named after its author, the 2nd-century BC annals, Lüshi Chunqiu, also notes, The lodestone makes iron approach, or it attracts it. The earliest mention of the attraction of a needle is in a 1st-century work Lunheng, by the 12th century the Chinese were known to use the lodestone compass for navigation. They sculpted a directional spoon from lodestone in such a way that the handle of the spoon always pointed south, alexander Neckam, by 1187, was the first in Europe to describe the compass and its use for navigation. In 1269, Peter Peregrinus de Maricourt wrote the Epistola de magnete, in 1282, the properties of magnets and the dry compass were discussed by Al-Ashraf, a Yemeni physicist, astronomer, and geographer. In 1600, William Gilbert published his De Magnete, Magneticisque Corporibus, in this work he describes many of his experiments with his model earth called the terrella. From his experiments, he concluded that the Earth was itself magnetic and this landmark experiment is known as Ørsteds Experiment. James Clerk Maxwell synthesized and expanded these insights into Maxwells equations, unifying electricity, magnetism, in 1905, Einstein used these laws in motivating his theory of special relativity, requiring that the laws held true in all inertial reference frames. Magnetism, at its root, arises from two sources, Electric current, Spin magnetic moments of elementary particles. The magnetic moments of the nuclei of atoms are thousands of times smaller than the electrons magnetic moments. Nuclear magnetic moments are very important in other contexts, particularly in nuclear magnetic resonance
23.
Earth's magnetic field
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Its magnitude at the Earths surface ranges from 25 to 65 microteslas. The North geomagnetic pole, located near Greenland in the hemisphere, is actually the south pole of the Earths magnetic field. Unlike a bar magnet, Earths magnetic field changes over time because it is generated by a geodynamo, however, at irregular intervals averaging several hundred thousand years, the Earths field reverses and the North and South Magnetic Poles relatively abruptly switch places. These reversals of the geomagnetic poles leave a record in rocks that are of value to paleomagnetists in calculating geomagnetic fields in the past, such information in turn is helpful in studying the motions of continents and ocean floors in the process of plate tectonics. The magnetosphere is the region above the ionosphere that is defined by the extent of the Earths magnetic field in space. The Earths magnetic field serves to deflect most of the solar wind, one stripping mechanism is for gas to be caught in bubbles of magnetic field, which are ripped off by solar winds. The study of past magnetic field of the Earth is known as paleomagnetism, reversals also provide the basis for magnetostratigraphy, a way of dating rocks and sediments. The field also magnetizes the crust, and magnetic anomalies can be used to search for deposits of metal ores, humans have used compasses for direction finding since the 11th century A. D. and for navigation since the 12th century. Although the magnetic declination does shift with time, this wandering is slow enough that a simple compass remains useful for navigation, using magnetoception various other organisms, ranging from some types of bacteria to pigeons, use the Earths magnetic field for orientation and navigation. At any location, the Earths magnetic field can be represented by a three-dimensional vector, a typical procedure for measuring its direction is to use a compass to determine the direction of magnetic North. Its angle relative to true North is the declination or variation, facing magnetic North, the angle the field makes with the horizontal is the inclination or magnetic dip. The intensity of the field is proportional to the force it exerts on a magnet, another common representation is in X, Y and Z coordinates. The intensity of the field is measured in gauss, but is generally reported in nanoteslas. A nanotesla is also referred to as a gamma, the tesla is the SI unit of the Magnetic field, B. The Earths field ranges between approximately 25,000 and 65,000 nT, by comparison, a strong refrigerator magnet has a field of about 10,000,000 nanoteslas. A map of intensity contours is called an isodynamic chart, as the World Magnetic Model shows, the intensity tends to decrease from the poles to the equator. A minimum intensity occurs in the South Atlantic Anomaly over South America while there are maxima over northern Canada, Siberia, the inclination is given by an angle that can assume values between -90° to 90°. In the northern hemisphere, the field points downwards and it is straight down at the North Magnetic Pole and rotates upwards as the latitude decreases until it is horizontal at the magnetic equator
24.
Magnetic field
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A magnetic field is the magnetic effect of electric currents and magnetic materials. The magnetic field at any point is specified by both a direction and a magnitude, as such it is represented by a vector field. The term is used for two distinct but closely related fields denoted by the symbols B and H, where H is measured in units of amperes per meter in the SI, B is measured in teslas and newtons per meter per ampere in the SI. B is most commonly defined in terms of the Lorentz force it exerts on moving electric charges, Magnetic fields can be produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. In quantum physics, the field is quantized and electromagnetic interactions result from the exchange of photons. Magnetic fields are used throughout modern technology, particularly in electrical engineering. The Earth produces its own field, which is important in navigation. Rotating magnetic fields are used in electric motors and generators. Magnetic forces give information about the carriers in a material through the Hall effect. The interaction of magnetic fields in electric devices such as transformers is studied in the discipline of magnetic circuits, noting that the resulting field lines crossed at two points he named those points poles in analogy to Earths poles. He also clearly articulated the principle that magnets always have both a north and south pole, no matter how finely one slices them, almost three centuries later, William Gilbert of Colchester replicated Petrus Peregrinus work and was the first to state explicitly that Earth is a magnet. Published in 1600, Gilberts work, De Magnete, helped to establish magnetism as a science, in 1750, John Michell stated that magnetic poles attract and repel in accordance with an inverse square law. Charles-Augustin de Coulomb experimentally verified this in 1785 and stated explicitly that the north and south poles cannot be separated, building on this force between poles, Siméon Denis Poisson created the first successful model of the magnetic field, which he presented in 1824. In this model, a magnetic H-field is produced by magnetic poles, three discoveries challenged this foundation of magnetism, though. First, in 1819, Hans Christian Ørsted discovered that an electric current generates a magnetic field encircling it, then in 1820, André-Marie Ampère showed that parallel wires having currents in the same direction attract one another. Finally, Jean-Baptiste Biot and Félix Savart discovered the Biot–Savart law in 1820, extending these experiments, Ampère published his own successful model of magnetism in 1825. This has the benefit of explaining why magnetic charge can not be isolated. Also in this work, Ampère introduced the term electrodynamics to describe the relationship between electricity and magnetism, in 1831, Michael Faraday discovered electromagnetic induction when he found that a changing magnetic field generates an encircling electric field
25.
Torque
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Torque, moment, or moment of force is rotational force. Just as a force is a push or a pull. Loosely speaking, torque is a measure of the force on an object such as a bolt or a flywheel. For example, pushing or pulling the handle of a wrench connected to a nut or bolt produces a torque that loosens or tightens the nut or bolt, the symbol for torque is typically τ, the lowercase Greek letter tau. When it is called moment of force, it is denoted by M. The SI unit for torque is the newton metre, for more on the units of torque, see Units. This article follows US physics terminology in its use of the word torque, in the UK and in US mechanical engineering, this is called moment of force, usually shortened to moment. In US physics and UK physics terminology these terms are interchangeable, unlike in US mechanical engineering, Torque is defined mathematically as the rate of change of angular momentum of an object. The definition of states that one or both of the angular velocity or the moment of inertia of an object are changing. Moment is the term used for the tendency of one or more applied forces to rotate an object about an axis. For example, a force applied to a shaft causing acceleration, such as a drill bit accelerating from rest. By contrast, a force on a beam produces a moment, but since the angular momentum of the beam is not changing. Similarly with any force couple on an object that has no change to its angular momentum and this article follows the US physics terminology by calling all moments by the term torque, whether or not they cause the angular momentum of an object to change. The concept of torque, also called moment or couple, originated with the studies of Archimedes on levers, the term torque was apparently introduced into English scientific literature by James Thomson, the brother of Lord Kelvin, in 1884. A force applied at an angle to a lever multiplied by its distance from the levers fulcrum is its torque. A force of three newtons applied two metres from the fulcrum, for example, exerts the same torque as a force of one newton applied six metres from the fulcrum. More generally, the torque on a particle can be defined as the product, τ = r × F, where r is the particles position vector relative to the fulcrum. Alternatively, τ = r F ⊥, where F⊥ is the amount of force directed perpendicularly to the position of the particle, any force directed parallel to the particles position vector does not produce a torque
26.
North Magnetic Pole
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Magnetic declination or variation is the angle on the horizontal plane between magnetic north and true north. This angle varies depending on position on the Earths surface, and changes over time. The angle between magnetic and grid meridians is called grid magnetic angle, grid variation, or grivation. ”By convention, declination is positive when magnetic north is east of true north, and negative when it is to the west. Isogonic lines are lines on the Earths surface along which the declination has the constant value. The lowercase Greek letter δ is frequently used as the symbol for magnetic declination, Magnetic declination varies both from place to place and with the passage of time. As a traveller cruises the east coast of the United States, for example, the declination at London, UK is one degree 7 minutes west, and as the country is quite small that figure is fairly good for the whole of the country. It is reducing, and scientists predict that in about 2050 it will be zero, similarly, secular changes to these flows result in slow changes to the field strength and direction at the same point on the Earth. The magnetic declination in an area may change slowly over time, possibly as little as 2–2.5 degrees every hundred years or so. For a location closer to the pole like Ivujivik, the declination may change by 1 degree every three years and this may be insignificant to most travellers, but can be important if using magnetic bearings from old charts or metes in old deeds for locating places with any precision. As an example of how variation changes over time, see the two charts of the area, below, surveyed 124 years apart. The 1884 chart shows a variation of 8 degrees,20 minutes West, the 2008 chart shows 13 degrees,15 minutes West. The instrument used to perform this measurement is known as a declinometer, the approximate position of the north celestial pole is indicated by Polaris. In the northern hemisphere, declination can therefore be determined as the difference between the magnetic bearing and a visual bearing on Polaris. Polaris currently traces a circle 0. 75° in radius around the celestial pole. At high latitudes a plumb-bob is helpful to sight Polaris against an object close to the horizon. A rough estimate of the local declination can be determined from a general isogonic chart of the world or a continent, isogonic lines are also shown on aeronautical and nautical charts. Larger-scale local maps may indicate current local declination, often with the aid of a schematic diagram, unless the area depicted is very small, declination may vary measurably over the extent of the map, so the data may be referred to a specific location on the map. The current rate and direction of change may also be shown, the same diagram may show the angle of grid north, which may differ from true north
27.
South Magnetic Pole
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The South Magnetic Pole is the wandering point on the Earths Southern Hemisphere where the geomagnetic field lines are directed vertically upwards. It should not be confused with the South Geomagnetic Pole described later, for historical reasons, the end of a freely hanging magnet that points north is itself called the north pole of the magnet, and the other end, pointing south, is called the magnets south pole. Because opposite poles attract, the Earths South Magnetic Pole is physically actually a magnetic north pole, the South Magnetic Pole is constantly shifting due to changes in the Earths magnetic field. As of 2005 it was calculated to lie at 64°31′48″S 137°51′36″E, placing it off the coast of Antarctica, in 2015 it lay at 64. 28°S136. 59°E / -64.28,136.59. That point lies outside the Antarctic Circle, due to polar drift, the pole is moving northwest by about 10 to 15 kilometers per year. Its current distance from the actual Geographic South Pole is approximately 2860 km, the nearest permanent science station is Dumont dUrville Station. Wilkes Land contains a large gravitational mass concentration, early unsuccessful attempts to reach the magnetic south pole included those of French explorer Dumont dUrville, American Charles Wilkes and Briton James Clark Ross. On 16 January 1909 three men from Sir Ernest Shackletons Nimrod Expedition claimed to have found the South Magnetic Pole, however, there is now some doubt as to whether their location was correct. The approximate position of the pole on 16 January 1909 was 72. 25°S155. 15°E / -72.25,155.15. The South Magnetic Pole has also estimated by fits to global sets of data such as the World Magnetic Model. For earlier years back to about 1600, the model GUFM1 is used, based on a compilation of data from ship logs, the Earths geomagnetic field can be approximated by a tilted dipole placed at the center of the Earth. The South Geomagnetic Pole is the point where the axis of this best-fitting tilted dipole intersects the Earths surface in the southern hemisphere. As of 2005 it was calculated to be located at 79. 74°S108. 22°E / -79.74,108.22, because the field is not an exact dipole, the South Geomagnetic Pole does not coincide with the South Magnetic Pole. Furthermore, the South Geomagnetic Pole is wandering for the reason its northern magnetic counterpart wanders. North Magnetic Pole Polar alignment Australian Antarctic Division
28.
Jewel bearing
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A jewel bearing is a plain bearing in which a metal spindle turns in a jewel-lined pivot hole. The hole is typically shaped like a torus and is larger than the shaft diameter. The jewel material is usually synthetic sapphire or ruby, Jewel bearings are used in precision instruments where low friction, long life, and dimensional accuracy are important. Their largest use is in mechanical watches, Jewel bearings were invented in 1704 for use in watches by Nicolas Fatio de Duillier, Peter Debaufre, and Jacob Debaufre, who received an English patent for the idea. Originally natural jewels were used, such as diamond, sapphire, ruby, in 1902, a process to make synthetic sapphire and ruby was invented by Auguste Verneuil, making jewelled bearings much cheaper. Today most jewelled bearings are synthetic ruby or sapphire, historically, jewel pivots were made by grinding using diamond abrasive. Modern jewel pivots are made using high-powered lasers, chemical etching. They are known for their low kinetic friction and highly consistent static friction, the static coefficient of friction of brass-on-steel is 0.35, while that of sapphire-on-steel is 0. 10–0.15. Sapphire surfaces are hard and durable, with Mohs hardness of 9 and Knoop hardness of 1800. Disadvantages include brittleness and fragility, limited availability/applicability in medium and large bearing sizes and capacities, the predominant use of jewel bearings is in mechanical watches, where their low and predictable friction improves watch accuracy as well as improving bearing life. Manufacturers listed the number of jewels prominently on the face or back. The other major use of jeweled bearings is in measuring instruments. They are typically used for delicate linkages that must carry very small forces, in such as galvanometers, compasses, gyroscopes, gimbals. Bearing bores are typically smaller than 1 mm and support loads weighing less than 1 gram, although they are made as large as 10 mm, incabloc shock protection system Baillie, G. H. Watchmakers And Clockmakers Of The World. Paul Baillio, Jewel Bearings Solve Light Load Problems A. C
29.
North Pole
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The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is defined as the point in the Northern Hemisphere where the Earths axis of rotation meets its surface. The North Pole is the northernmost point on the Earth, lying diametrically opposite the South Pole and it defines geodetic latitude 90° North, as well as the direction of true north. At the North Pole all directions point south, all lines of longitude converge there, along tight latitude circles, counterclockwise is east and clockwise is west. The North Pole is at the center of the Northern Hemisphere, while the South Pole lies on a continental land mass, the North Pole is located in the middle of the Arctic Ocean amid waters that are almost permanently covered with constantly shifting sea ice. This makes it impractical to construct a permanent station at the North Pole, however, the Soviet Union, and later Russia, constructed a number of manned drifting stations on a generally annual basis since 1937, some of which have passed over or very close to the Pole. Since 2002, the Russians have also established a base, Barneo. This operates for a few weeks during early spring, studies in the 2000s predicted that the North Pole may become seasonally ice-free because of Arctic ice shrinkage, with timescales varying from 2016 to the late 21st century or later. The sea depth at the North Pole has been measured at 4,261 m by the Russian Mir submersible in 2007 and at 4,087 m by USS Nautilus in 1958. The nearest land is said to be Kaffeklubben Island, off the northern coast of Greenland about 700 km away. The nearest permanently inhabited place is Alert in the Qikiqtaaluk Region, Nunavut, Canada, around the beginning of the 20th century astronomers noticed a small apparent variation of latitude, as determined for a fixed point on Earth from the observation of stars. Part of this variation could be attributed to a wandering of the Pole across the Earths surface, the wandering has several periodic components and an irregular component. The component with a period of about 435 days is identified with the eight-month wandering predicted by Euler and is now called the Chandler wobble after its discoverer and it is desirable to tie the system of Earth coordinates to fixed landforms. Of course, given plate tectonics and isostasy, there is no system in all geographic features are fixed. Yet the International Earth Rotation and Reference Systems Service and the International Astronomical Union have defined a framework called the International Terrestrial Reference System. As early as the 16th century, many eminent people correctly believed that the North Pole was in a sea and it was therefore hoped that passage could be found through ice floes at favorable times of the year. Several expeditions set out to find the way, generally with whaling ships, one of the earliest expeditions to set out with the explicit intention of reaching the North Pole was that of British naval officer William Edward Parry, who in 1827 reached latitude 82°45′ North. In 1871 the Polaris expedition, a US attempt on the Pole led by Charles Francis Hall, another British Royal Navy attempt on the pole, part of the British Arctic Expedition, by Commander Albert H. Markham reached a then-record 83°2026 North in May 1876 before turning back. An 1879–1881 expedition commanded by US naval officer George W. DeLong ended tragically when their ship, over half the crew, including DeLong, were lost
30.
Gyrocompass
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A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth to find geographical direction automatically. Aircraft commonly use gyroscopic instruments for navigation and attitude monitoring, for details, see Flight instruments, a gyroscope, not to be confused with gyrocompass, is a spinning wheel mounted on a set of gimbals so that its axis is free to orient itself in any way. Since our planet rotates, it appears to an observer on Earth that a gyroscopes axis is completing a full rotation once every 24 hours. This friction force caused by the results in a torque acting on the axis. Once the axis points toward the pole, it will appear to be stationary. This is because true north is the direction for which the gyroscope can remain on the surface of the earth. This axis orientation is considered to be a point of potential energy. Another, more practical, method is to use weights to force the axis of the compass to remain horizontal, in this case, gravity will apply a torque forcing the compasss axis toward true north. Because the weights will confine the compasss axis to be horizontal with respect to the Earths surface, but with respect to the Earths surface, the compass will appear to be stationary and pointing along the Earths surface toward the true North Pole. We consider a gyrocompass as a gyroscope which is free to rotate one of its symmetry axes. Therefore there are two independent local rotations, in addition to these rotations we consider the rotation of the Earth about its north-south axis, and we model the planet as a perfect sphere. We neglect friction and also the rotation of the Earth about the Sun, in this case a non-rotating observer located at the center of the Earth can be approximated as being an inertial frame. We establish cartesian coordinates for such an observer, and the barycenter of the gyroscope is located at a distance R from the center of the Earth, let us consider another observer located at the center of the Earth but rotating about the NS-axis by Ω. We establish coordinates attached to this observer as =, so that the unit X ^1 versor T is mapped to the point T, for the 2-O neither the Earth nor the barycenter of the gyroscope is moving. The rotation of 2-O relative to 1-O is performed with angular velocity Ω → = T and we suppose that the X2 axis denotes points with zero longitude. We now rotate about the Z2 axis, so that the X3 -axis has the longitude of the barycenter, with the next rotation we bring the Z3 axis along the local zenith of the barycenter. This can be achieved by the orthogonal matrix =, so that the Z ^3 versor T is mapped to the point T. We now choose another coordinate basis whose origin is located at the barycenter of the gyroscope
31.
Gyroscope
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A gyroscope is a spinning wheel or disc in which the axis of rotation is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum, because of this, gyroscopes are useful for measuring or maintaining orientation. Due to their precision, gyroscopes are used in gyrotheodolites to maintain direction in tunnel mining. Gyroscopes can be used to construct gyrocompasses, which complement or replace magnetic compasses, a gyroscope is a wheel mounted in two or three gimbals, which are a pivoted supports that allow the rotation of the wheel about a single axis. In the case of a gyroscope with two gimbals, the gimbal, which is the gyroscope frame, is mounted so as to pivot about an axis in its own plane determined by the support. This outer gimbal possesses one degree of freedom and its axis possesses none. The inner gimbal is mounted in the frame so as to pivot about an axis in its own plane that is always perpendicular to the pivotal axis of the gyroscope frame. This inner gimbal has two degrees of rotational freedom, the axle of the spinning wheel defines the spin axis. The rotor is constrained to spin about an axis, which is perpendicular to the axis of the inner gimbal. So the rotor possesses three degrees of freedom and its axis possesses two. The wheel responds to a force applied to the axis by a reaction force to the output axis. The behaviour of a gyroscope can be most easily appreciated by consideration of the front wheel of a bicycle. If the wheel is leaned away from the vertical so that the top of the moves to the left. In other words, rotation on one axis of the turning wheel produces rotation of the third axis, a gyroscope flywheel will roll or resist about the output axis depending upon whether the output gimbals are of a free or fixed configuration. Examples of some free-output-gimbal devices would be the attitude reference gyroscopes used to sense or measure the pitch, roll, the centre of gravity of the rotor can be in a fixed position. Some gyroscopes have mechanical equivalents substituted for one or more of the elements, for example, the spinning rotor may be suspended in a fluid, instead of being pivotally mounted in gimbals. In some special cases, the outer gimbal may be omitted so that the rotor has two degrees of freedom. Essentially, a gyroscope is a top combined with a pair of gimbals, Tops were invented in many different civilizations, including classical Greece, Rome, and China
32.
Ship
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Historically, a ship was a sailing vessel with at least three square-rigged masts and a full bowsprit. Ships are generally distinguished from boats, based on size, shape, Ships have been important contributors to human migration and commerce. They have supported the spread of colonization and the trade, but have also served scientific, cultural. After the 16th century, new crops that had come from, Ship transport is responsible for the largest portion of world commerce. As of 2016, there were more than 49,000 merchant ships, of these 28% were oil tankers, 43% were bulk carriers, and 13% were container ships. Military forces operate vessels for naval warfare and to transport and support forces ashore, the top 50 navies had a median fleet of 88 surface vessels each, according to various sources. There is no definition of what distinguishes a ship from a boat. Ships can usually be distinguished from boats based on size and the ability to operate independently for extended periods. A legal definition of ship from Indian case law is a vessel that carries goods by sea, a common notion is that a ship can carry a boat, but not vice versa. American and British 19th Century maritime law distinguished vessels from other craft, ships and boats fall in one legal category, a number of large vessels are usually referred to as boats. Other types of vessel which are traditionally called boats are Great Lakes freighters, riverboats. Though large enough to carry their own boats and heavy cargoes, in most maritime traditions ships have individual names, and modern ships may belong to a ship class often named after its first ship. The first known vessels date back about 10,000 years ago, the first navigators began to use animal skins or woven fabrics as sails. Affixed to the top of a pole set upright in a boat and this allowed men to explore widely, allowing for the settlement of Oceania for example. By around 3000 BC, Ancient Egyptians knew how to assemble wooden planks into a hull and they used woven straps to lash the planks together, and reeds or grass stuffed between the planks helped to seal the seams. Sneferus ancient cedar wood ship Praise of the Two Lands is the first reference recorded to a ship being referred to by name, the ancient Egyptians were perfectly at ease building sailboats. A remarkable example of their skills was the Khufu ship. Aksum was known by the Greeks for having seaports for ships from Greece, a panel found at Mohenjodaro depicted a sailing craft
33.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
34.
Ferromagnetism
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Not to be confused with Ferrimagnetism, for an overview see Magnetism. Ferromagnetism is the mechanism by which certain materials form permanent magnets. In physics, several different types of magnetism are distinguished, an everyday example of ferromagnetism is a refrigerator magnet used to hold notes on a refrigerator door. The attraction between a magnet and ferromagnetic material is the quality of magnetism first apparent to the ancient world, permanent magnets are either ferromagnetic or ferrimagnetic, as are the materials that are noticeably attracted to them. Only a few substances are ferromagnetic, the common ones are iron, nickel, cobalt and most of their alloys, some compounds of rare earth metals, and a few naturally occurring minerals, including some varieties of lodestone. Historically, the term ferromagnetism was used for any material that could exhibit spontaneous magnetization and this general definition is still in common use. In particular, a material is ferromagnetic in this sense only if all of its magnetic ions add a positive contribution to the net magnetization. If some of the magnetic ions subtract from the net magnetization, if the moments of the aligned and anti-aligned ions balance completely so as to have zero net magnetization, despite the magnetic ordering, then it is an antiferromagnet. These alignment effects only occur at temperatures below a critical temperature. Among the first investigations of ferromagnetism are the works of Aleksandr Stoletov on measurement of the magnetic permeability of ferromagnetics. The table on the right lists a selection of ferromagnetic and ferrimagnetic compounds, ferromagnetism is a property not just of the chemical make-up of a material, but of its crystalline structure and microstructure. There are ferromagnetic metal alloys whose constituents are not themselves ferromagnetic, called Heusler alloys, conversely there are non-magnetic alloys, such as types of stainless steel, composed almost exclusively of ferromagnetic metals. Amorphous ferromagnetic metallic alloys can be made by rapid quenching of a liquid alloy. These have the advantage that their properties are isotropic, this results in low coercivity, low hysteresis loss, high permeability. One such typical material is a transition metal-metalloid alloy, made from about 80% transition metal, a relatively new class of exceptionally strong ferromagnetic materials are the rare-earth magnets. They contain lanthanide elements that are known for their ability to carry large magnetic moments in well-localized f-orbitals, a number of actinide compounds are ferromagnets at room temperature or exhibit ferromagnetism upon cooling. PuP is a paramagnet with cubic symmetry at room temperature, in its ferromagnetic state, PuPs easy axis is in the <100> direction. In NpFe2 the easy axis is <111>, above TC ≈500 K NpFe2 is also paramagnetic and cubic
35.
Electric current
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An electric current is a flow of electric charge. In electric circuits this charge is carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionised gas. The SI unit for measuring a current is the ampere. Electric current is measured using a device called an ammeter, electric currents cause Joule heating, which creates light in incandescent light bulbs. They also create magnetic fields, which are used in motors, inductors and generators, the particles that carry the charge in an electric current are called charge carriers. In metals, one or more electrons from each atom are loosely bound to the atom and these conduction electrons are the charge carriers in metal conductors. The conventional symbol for current is I, which originates from the French phrase intensité de courant, current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of current is named, in formulating the eponymous Ampères force law. The notation travelled from France to Great Britain, where it became standard, in a conductive material, the moving charged particles which constitute the electric current are called charge carriers. In other materials, notably the semiconductors, the carriers can be positive or negative. Positive and negative charge carriers may even be present at the same time, a flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. Since current can be the flow of positive or negative charges. The direction of current is arbitrarily defined as the same direction as positive charges flow. This is called the direction of current I. If the current flows in the direction, the variable I has a negative value. When analyzing electrical circuits, the direction of current through a specific circuit element is usually unknown. Consequently, the directions of currents are often assigned arbitrarily
36.
Fluxgate compass
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A compass is a simple example of a magnetometer, one that measures the direction of an ambient magnetic field. Magnetometers are widely used for measuring the Earths magnetic field and in geophysical surveys to detect anomalies of various types. They are also used in the military to detect submarines, consequently, some countries, such as the United States, Canada and Australia, classify the more sensitive magnetometers as military technology, and control their distribution. Magnetic fields are vector quantities characterized by strength and direction. The strength of a field is measured in units of tesla in the SI units. 10,000 gauss are equal to one tesla, measurements of the Earths magnetic field are often quoted in units of nanotesla, also called a gamma. Gaussmeters and teslameters are magnetometers that measure in units of gauss or tesla, in some contexts, magnetometer is the term used for an instrument that measures fields of less than 1 millitesla and gaussmeter is used for those measuring greater than 1 mT. There are two types of magnetometer measurement. Vector magnetometers measure the components of a magnetic field. Total field magnetometers or scalar magnetometers measure the magnitude of the magnetic field. Magnetometers used to study the Earths magnetic field may express the components of the field in terms of declination. Absolute magnetometers measure the magnitude or vector magnetic field, using an internal calibration or known physical constants of the magnetic sensor. Relative magnetometers measure magnitude or vector magnetic field relative to a fixed but uncalibrated baseline, also called variometers, relative magnetometers are used to measure variations in magnetic field. Magnetometers may also be classified by their situation or intended use, stationary magnetometers are installed to a fixed position and measurements are taken while the magnetometer is stationary. Portable or mobile magnetometers are meant to be used while in motion, laboratory magnetometers are used to measure the magnetic field of materials placed within them and are typically stationary. The performance and capabilities of magnetometers are described through their technical specifications, major specifications include Sample rate is the amount of readings given per second. The inverse is the time in seconds per reading. Sample rate is important in mobile magnetometers, the sample rate, bandwidth or bandpass characterizes how well a magnetometer tracks rapid changes in magnetic field
37.
Global Positioning System
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The Global Positioning System is a space-based radionavigation system owned by the United States government and operated by the United States Air Force. The GPS system operates independently of any telephonic or internet reception, the GPS system provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, however, the US government can selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War. The U. S. Department of Defense developed the system and it became fully operational in 1995. Roger L. Easton of the Naval Research Laboratory, Ivan A, getting of The Aerospace Corporation, and Bradford Parkinson of the Applied Physics Laboratory are credited with inventing it. Announcements from Vice President Al Gore and the White House in 1998 initiated these changes, in 2000, the U. S. Congress authorized the modernization effort, GPS III. In addition to GPS, other systems are in use or under development, mainly because of a denial of access. The Russian Global Navigation Satellite System was developed contemporaneously with GPS, GLONASS can be added to GPS devices, making more satellites available and enabling positions to be fixed more quickly and accurately, to within two meters. There are also the European Union Galileo positioning system and Chinas BeiDou Navigation Satellite System, special and general relativity predict that the clocks on the GPS satellites would be seen by the Earths observers to run 38 microseconds faster per day than the clocks on the Earth. The GPS calculated positions would quickly drift into error, accumulating to 10 kilometers per day, the relativistic time effect of the GPS clocks running faster than the clocks on earth was corrected for in the design of GPS. The Soviet Union launched the first man-made satellite, Sputnik 1, two American physicists, William Guier and George Weiffenbach, at Johns Hopkinss Applied Physics Laboratory, decided to monitor Sputniks radio transmissions. Within hours they realized that, because of the Doppler effect, the Director of the APL gave them access to their UNIVAC to do the heavy calculations required. The next spring, Frank McClure, the deputy director of the APL, asked Guier and Weiffenbach to investigate the inverse problem — pinpointing the users location and this led them and APL to develop the TRANSIT system. In 1959, ARPA also played a role in TRANSIT, the first satellite navigation system, TRANSIT, used by the United States Navy, was first successfully tested in 1960. It used a constellation of five satellites and could provide a navigational fix approximately once per hour, in 1967, the U. S. Navy developed the Timation satellite, which proved the feasibility of placing accurate clocks in space, a technology required by GPS. In the 1970s, the ground-based OMEGA navigation system, based on comparison of signal transmission from pairs of stations. Limitations of these systems drove the need for a more universal navigation solution with greater accuracy, during the Cold War arms race, the nuclear threat to the existence of the United States was the one need that did justify this cost in the view of the United States Congress. This deterrent effect is why GPS was funded and it is also the reason for the ultra secrecy at that time
38.
GPS navigation device
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The Global Positioning System is a global navigation satellite system made up of a network of a minimum of 24, but currently 30, satellites placed into orbit by the U. S. Department of Defense. The GPS was originally developed for use by the United States military, but in the 1980s, though the GPS satellite data is free and works anywhere in the world, the GPS device and the associated software must be bought or rented. A GPS device can retrieve from the GPS system location and time information in all weather conditions, a GPS reception requires an unobstructed line of sight to four or more GPS satellites, and is subject to poor satellite signal conditions. Obstructed lines of sight may arise from a canopy or inside a structure, such as in a building. Today, most standalone GPS receivers are used in automobiles, however, the mobile network part of the A-GPS technology would not be available when the smartphone is outside the range of the mobile reception network. The Russian Global Navigation Satellite System was developed contemporaneously with GPS, GLONASS can be added to GPS devices which makes more satellites available and enabling positions to be fixed more quickly and accurately, to within 2 meters. As with many other technological breakthroughs of the latter 20th century, the multibillion-dollar expense of this program was initially justified by military interest. In 1960, the US Navy put into service its Transit satellite based system to aid in ship navigation. From 1960 to 1982, as the benefits were proven over time, in 1973, the US military began to plan for a comprehensive worldwide navigational system which eventually became known as the GPS. This new availability of the US military GPS system for civilian use required a technical collaboration with the private sector for some time. In 1989, Magellan Navigation Inc. unveiled its Magellan NAV 1000—the world’s first commercial handheld GPS receiver and these units initially sold for approximately $2,900 each. In 2000, the Clinton administration ordered the removal of military use signal restrictions, as GPS navigation systems became more and more widespread and popular, the pricing of such systems began to fall, and their widespread availability steadily increased. Also, several manufacturers of these systems, such as Garmin, Benefon, Mio. Mitac Mio 168 was the first PocketPC to contain a built-in GPS receiver, benefons 1999 entry into the market also presented users with the worlds first phone based GPS navigation system. Later, as the phone industry developed, a GPS chip eventually became standard equipment for most smart phone manufacturers. To date, ever more popular GPS navigation systems and devices continue to proliferate with newly developed software and hardware applications. While the American GPS was the first satellite system to be deployed on a fully global scale, and to be made available for commercial use. Due to military and other concerns, similar global or regional systems have been, or will soon be deployed by Russia, the European Union, China, India, GPS navigation devices vary in sensitivity, speed, vulnerability to multipath propagation, and other performance parameters
39.
History of the compass
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A compass is an instrument used for navigation and orientation that shows direction relative to the geographic cardinal directions, or points. Usually, a called a compass rose shows the directions north, south, east. When the compass is used, the rose can be aligned with the geographic directions, so, for example. Frequently, in addition to the rose or sometimes instead of it, North corresponds to zero degrees, and the angles increase clockwise, so east is 90 degrees, south is 180, and west is 270. These numbers allow the compass to show azimuths or bearings, which are stated in this notation. The magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty, the first usage of a compass recorded in Western Europe and the Islamic world occurred around the early 13th century. The magnetic compass is the most familiar compass type and it functions as a pointer to magnetic north, the local magnetic meridian, because the magnetized needle at its heart aligns itself with the horizontal component of the Earths magnetic field. The needle is mounted on a pivot point, in better compasses a jewel bearing. When the compass is level, the needle turns until, after a few seconds to allow oscillations to die out. In navigation, directions on maps are usually expressed with reference to geographical or true north, the direction toward the Geographical North Pole, the rotation axis of the Earth. Depending on where the compass is located on the surface of the Earth the angle between north and magnetic north, called magnetic declination can vary widely with geographic location. The local magnetic declination is given on most maps, to allow the map to be oriented with a parallel to true north. The location of the Earths magnetic poles slowly change with time, the effect of this means a map with the latest declination information should be used. Some magnetic compasses include means to compensate for the magnetic declination. The first compasses in ancient Han dynasty China were made of lodestone, the compass was later used for navigation during the Song Dynasty of the 11th century. Later compasses were made of iron needles, magnetized by striking them with a lodestone, dry compasses began to appear around 1300 in Medieval Europe and the Islamic world. This was supplanted in the early 20th century by the magnetic compass. Modern compasses usually use a needle or dial inside a capsule completely filled with a liquid
40.
Lodestone
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A lodestone is a naturally magnetized piece of the mineral magnetite. They are naturally occurring magnets, which can attract iron, the property of magnetism was first discovered in antiquity through lodestones. Lodestone is one of the few minerals that is found naturally magnetized, magnetite is black or brownish-black, with a metallic luster, a Mohs hardness of 5. 5–6.5 and a black streak. The process by which lodestone is created has long been a question in geology. Only a small amount of the magnetite on Earth is found magnetized as lodestone, ordinary magnetite is attracted to a magnetic field like iron and steel is, but does not tend to become magnetized itself, it has too low a magnetic coercivity to stay magnetized for long. Microscopic examination of lodestones has found them to be made of magnetite with inclusions of maghemite, often with impurity metal ions of titanium, aluminium and this inhomogeneous crystalline structure gives this variety of magnetite sufficient coercivity to remain magnetized and thus be a permanent magnet. The other question is how lodestones get magnetized, the Earths magnetic field at 0.5 gauss is too weak to magnetize a lodestone by itself. The leading theory is that lodestones are magnetized by the magnetic fields surrounding lightning bolts. This is supported by the observation that they are found near the surface of the Earth. The name magnet may come from lodestones found in Magnesia, Anatolia, the earliest Chinese literary reference to magnetism occurs in a 4th-century BC Book of the Devil Valley Master. In the chronicle Lüshi Chunqiu, from the 2nd century BC, the earliest mention of a needles attraction appears in a work composed between 20 and 100 AD, the Lunheng, A lodestone attracts a needle. Medieval Chinese navigators were using lodestone compasses by the 12th century, detailed analysis of the Olmec artifact revealed that the bar was composed of hematite with titanium lamellae of Fe2–xTixO3 that accounted for the anomalous remanent magnetism of the artifact
41.
Middle Ages
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In the history of Europe, the Middle Ages or Medieval Period lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance, the Middle Ages is the middle period of the three traditional divisions of Western history, classical antiquity, the medieval period, and the modern period. The medieval period is subdivided into the Early, High. Population decline, counterurbanisation, invasion, and movement of peoples, the large-scale movements of the Migration Period, including various Germanic peoples, formed new kingdoms in what remained of the Western Roman Empire. In the seventh century, North Africa and the Middle East—once part of the Byzantine Empire—came under the rule of the Umayyad Caliphate, although there were substantial changes in society and political structures, the break with classical antiquity was not complete. The still-sizeable Byzantine Empire survived in the east and remained a major power, the empires law code, the Corpus Juris Civilis or Code of Justinian, was rediscovered in Northern Italy in 1070 and became widely admired later in the Middle Ages. In the West, most kingdoms incorporated the few extant Roman institutions, monasteries were founded as campaigns to Christianise pagan Europe continued. The Franks, under the Carolingian dynasty, briefly established the Carolingian Empire during the later 8th, the Crusades, first preached in 1095, were military attempts by Western European Christians to regain control of the Holy Land from Muslims. Kings became the heads of centralised nation states, reducing crime and violence, intellectual life was marked by scholasticism, a philosophy that emphasised joining faith to reason, and by the founding of universities. Controversy, heresy, and the Western Schism within the Catholic Church paralleled the conflict, civil strife. Cultural and technological developments transformed European society, concluding the Late Middle Ages, the Middle Ages is one of the three major periods in the most enduring scheme for analysing European history, classical civilisation, or Antiquity, the Middle Ages, and the Modern Period. Medieval writers divided history into periods such as the Six Ages or the Four Empires, when referring to their own times, they spoke of them as being modern. In the 1330s, the humanist and poet Petrarch referred to pre-Christian times as antiqua, leonardo Bruni was the first historian to use tripartite periodisation in his History of the Florentine People. Bruni and later argued that Italy had recovered since Petrarchs time. The Middle Ages first appears in Latin in 1469 as media tempestas or middle season, in early usage, there were many variants, including medium aevum, or middle age, first recorded in 1604, and media saecula, or middle ages, first recorded in 1625. The alternative term medieval derives from medium aevum, tripartite periodisation became standard after the German 17th-century historian Christoph Cellarius divided history into three periods, Ancient, Medieval, and Modern. The most commonly given starting point for the Middle Ages is 476, for Europe as a whole,1500 is often considered to be the end of the Middle Ages, but there is no universally agreed upon end date. English historians often use the Battle of Bosworth Field in 1485 to mark the end of the period
42.
Luminous paint
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Luminous paint or luminescent paint is paint that exhibits luminescence. In other words, it gives off light through fluorescence, phosphorescence. Fluorescent paints offer a range of pigments and chroma which also glow when exposed to the long-wave ultraviolet frequencies. These UV frequencies are found in sunlight and some artificial lights, human eyes perceive these changes as the unusual glow of fluorescence. The fluorescent type of luminescence is different from the natural bio-luminescence of bacteria, insects and fish such as the case of the firefly. Bio-luminescence involves no reflection at all, but living generation of light, there are both visible and invisible fluorescent paints. The visible appear under white light to be any bright color, invisible fluorescent paints appear transparent or pale under daytime lighting, but will glow under UV light in a limited range of colors. Since these can seem to disappear, they can be used to create a variety of clever effects, both types of fluorescent painting benefit when used within a contrasting ambiance of clean, matte-black backgrounds and borders. Such a black out effect will minimize other awareness, so cultivating the peculiar luminescence of UV fluorescence, both types of paints have extensive application where artistic lighting effects are desired, particularly in black box entertainments and environments such as theaters, bars, shrines, etc. Out-of-doors, however, UV wavelengths are scattered in space or absorbed by complex natural surfaces. Furthermore, the complex pigments will degrade quickly in sunlight, phosphorescent paint is commonly called glow-in-the-dark paint. It is made from such as silver-activated zinc sulfide or doped strontium aluminate. The mechanism for producing light is similar to that of fluorescent paint, phosphorescent paints have a sustained glow which lasts for up to 12 hours after exposure to light, fading over time. This type of paint has been used to mark escape paths in aircraft and for use such as stars applied to walls. It is an alternative to radioluminescent paint, kenners Lightning Bug Glo-Juice was a popular non-toxic paint product in 1968, marketed at children, alongside other glow-in-the-dark toys and novelties. When applied as a paint or a more sophisticated coating, phosphorescence can be used for detection or degradation measurements known as phosphor thermometry. Radioluminescent paint contains a radioactive isotope combined with a radioluminescent substance, the isotopes selected are typically strong emitters of fast electrons, preferred since this radiation will not penetrate an enclosure. Radioluminescent paints will glow without exposure to light until the radioactive isotope has decayed and they are therefore sometimes referred to as self-luminous
43.
Protractor
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A protractor is a measuring instrument, typically made of transparent plastic or glass, for measuring angles. Most protractors measure angles in degrees, radian-scale protractors measure angles in radians. Most protractors are divided into 180 equal parts and they are used for a variety of mechanical and engineering-related applications, but perhaps the most common use is in geometry lessons in schools. More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to measure the angle. A bevel protractor is a graduated circular protractor with one pivoted arm used for measuring or marking off angles, sometimes Vernier scales are attached to give more precise readings. It has wide application in architectural and mechanical drawing, although its use is decreasing with the availability of drawing software or CAD. Universal bevel protractors are also used by toolmakers, as they measure angles by mechanical contact they are classed as mechanical protractors, the bevel protractor is used to establish and test angles to very close tolerances. It reads to 5 minutes or 1/12° and can measure any angle from 0° to 360°, the bevel protractor consists of a beam, a graduated dial and a blade which is connected to a swivel plate by thumb nut and clamp. When the edges of the beam and blade are parallel, a mark on the swivel plate coincides with the zero line on the graduated dial. To measure an angle between the beam and the blade of 90° or less, the reading may be obtained direct from the number on the dial indicated by the mark on the swivel plate. To measure an angle of over 90°, subtract the number of degrees as indicated on the dial from 180°, as the dial is graduated from opposite zero marks to 90° each way. Since the spaces, both on the scale and the Vernier scale, are numbered both to the right and to the left from zero, any angle can be measured. The readings can be either to the right or to the left. The above picture illustrates a variety of uses of the bevel protractor, reading the Vernier scale, The bevel protractor Vernier scale may have graduations of 5′ or 1/12°. Each space on the Vernier scale is 5′ less than two spaces on the main scale, twenty four spaces on the Vernier scale equal in extreme length twenty three double degrees. Thus the difference between the occupied by 2° on a main scale and the space of the Vernier scale is equal to one twenty-fourth of 2°. Read off directly from the scale the number of whole degrees between 0 on this scale and the 0 of the Vernier scale. For example, Zero on the scale has moved 28 whole degrees to the right of the 0 on the main scale
44.
Orienteering
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Orienteering is a group of sports that requires navigational skills using a map and compass to navigate from point to point in diverse and usually unfamiliar terrain, and normally moving at speed. Participants are given a map, usually a specially prepared orienteering map. Originally a training exercise in land navigation for officers, orienteering has developed many variations. Among these, the oldest and the most popular is foot orienteering, Orienteering is included in the programs of world sporting events including the World Games and World Police and Fire Games. Orienteering sports combine significant navigation with a method of travel. Because the method of travel determines the equipment and tactics, each sport requires specific rules for competition and guidelines for orienteering event logistics. It is based in Finland and it claims on its website to aim to spread the sport of orienteering, to promote its development and to create and maintain an attractive world event programme. Since 1977 the IOF has been recognised by the IOC There are governing bodies for most of the nations that are represented in the sport of orienteering. These national bodies are the body for that nation. For example, the British Orienteering Federation is the governing body for the United Kingdom. The federation was founded in 1967 and it is made up of 13 constituent associations, for the United States, the national governing body is Orienteering USA. Most nations have some form of governing bodies. These are not rule-making bodies but are there to assist in coordinating clubs within that region, clubs are usually formed at a local level and affiliated to their national governing body. It is clubs who put on events usually open to all-comers, clubs may also put on practice, training, and social events. Open clubs are open to anyone and there is no restriction on joining them. Closed clubs restrict their membership to specific groups, for example, BAOC has restrictions on who may join, principally British Army personnel. The International Rogaining Federation governs rogaining, separate organizations govern competitive mounted orienteering in the United States and Europe. The International Amateur Radio Union governs amateur radio direction finding, Orienteering terms vary within English speaking countries, and in other countries where English is the de facto international language of orienteering
45.
Romer
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A Reference Card or Romer is a device for increasing the accuracy when reading a grid reference from a map. Made from transparent plastic, paper or other materials, they are found on most baseplate compasses. Essentially, it is a specially marked-out ruler which matches the scale of the map in use, some transparent versions have a small hole at the origin when this is not at the corner of the Reference Card. This allows access to the map such that the location could be marked with a pencil if using the Reference Card in reverse having been given a reference to start with. They are used in many types of land navigation, romers can easily be made yourself, by hand, by using a computer or by finding a website with instructions. They describe only an approximate location, the smaller the scale on the map, the less accurate the romer reading. On 1,25,000 maps, such as the British Ordnance Survey Explorer Series and this is larger than a football pitch. A more popular and accurate device is a Grid Reference Tool, although a registered design when it was first made and sold it was and still is much copied. The illustration below shows how the romer is used, here, we are plotting the reference 696018. The marks corresponding to on the romer are lined up along the gridlines, the hole near the corner yields the exact point, the church at Little Plumpton
46.
Hand compass
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A hand compass is a compact magnetic compass capable of one-hand use and fitted with a sighting device to record a precise bearing or azimuth to a given target or to determine a location. Hand or sighting compasses include instruments with simple notch-and-post alignment, prismatic sights, direct or lensatic sights, with the additional precision offered by the sighting arrangement, and depending upon construction, sighting compasses provide increased accuracy when measuring precise bearings to an objective. A hand compass may also include the various one-hand or pocket versions of the surveyors or geologists transit, while small portable compasses fitted with mechanical sighting devices have existed for a few hundred years, the first one-hand compass with a sighting device appeared around 1885. These soon evolved into elaborate and specialized models such as the Brunton Pocket Transit patented in 1894. Hand compasses were soon employed in the practice of forestry, geology, archaeology, speleology, preliminary cartography. In the United States, the compass became very popular among foresters seeking a compass to plot. While the Pocket Transit was more adequate for such work. Consequently, a new type of compass was introduced, the forester or cruiser compass. A screw base for a tripod or jacob staff was often fitted as well, by the late 1960s many foresters had begun using more modern liquid-damped compass designs, including mirror-sight protractor models such as the Silva Type 15 Ranger or the Suunto MC-1. These compasses were fast to use, particularly along straight lines and were sufficiently accurate for most forestry applications. Many models featured an optional quadrant scale instead of an azimuthal system, for increased accuracy, many professional hand compasses continue to be fitted with tripod mounts. While the hand continues to be widely employed in such work, it has been increasingly supplanted in recent years by use of the GPS. Instead of a needle or disc, most hand bearing compasses feature liquid damping with a floating card design. Equipped with a prism, the hand bearing compass allows instant reading of forward bearings from the user to an object or vessel. Modern examples of marine hand bearing compasses include the Suunto KB-14 and KB-77, and these compasses frequently have battery-illuminated or photoluminescent degree dials for use in low light or darkness. New York, McGraw-Hill Johnson, Mark, The Ultimate Desert Handbook, A Manual for Desert Hikers, Campers, finding Your Way In The Outdoors, Outdoor Life Press, ISBN 0-943822-41-6 Rutstrum, The Wilderness Route Finder, University of Minnesota Press, ISBN 0-8166-3661-3
