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124-533: The four cardinal directions , or cardinal points , are the four main compass directions: north , south , east , and west , commonly denoted by their initials N, S, E, and W respectively. Relative to north, the directions east, south, and west are at 90 degree intervals in the clockwise direction. The ordinal directions (also called the intercardinal directions ) are northeast (NE), southeast (SE), southwest (SW), and northwest (NW). The intermediate direction of every set of intercardinal and cardinal direction

248-465: A binnacle . This preserves the horizontal position. The magnetic compass is very reliable at moderate latitudes, but in geographic regions near the Earth's magnetic poles it becomes unusable. As the compass is moved closer to one of the magnetic poles, the magnetic declination, the difference between the direction to geographical north and magnetic north, becomes greater and greater. At some point close to

372-480: A jewel bearing , so it can turn easily. When the compass is held level, the needle turns until, after a few seconds to allow oscillations to die out, it settles into its equilibrium orientation. 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

496-587: A "Dark Age" that set Europe back a millennium. In contrast, German and English historians have tended to see Roman–Barbarian interaction as the replacement of a "tired, effete and decadent Mediterranean civilization" with a "more virile, martial, Nordic one". The scholar Guy Halsall has seen the barbarian movement as the result of the fall of the Roman Empire, not its cause. Archaeological discoveries have confirmed that Germanic and Slavic tribes were settled agriculturalists who were probably merely "drawn into

620-623: A "primeval urge" to push into the Mediterranean, the construction of the Great Wall of China causing a "domino effect" of tribes being forced westward, leading to the Huns falling upon the Goths who, in turn, pushed other Germanic tribes before them. In general, French and Italian scholars have tended to view this as a catastrophic event, the destruction of a civilization and the beginning of

744-526: A bowl of water it becomes a compass. Such devices were universally used as compasses until the invention of the box-like compass with a "dry" pivoting needle, sometime around 1300. Originally, many compasses were marked only as to the direction of magnetic north, or to the four cardinal points (north, south, east, west). Later, these were divided, in China into 24, and in Europe into 32 equally spaced points around

868-556: A common identity and ancestry. This was the Romantic ideal that there once had been a single German, Celtic or Slavic people who originated from a common homeland and spoke a common tongue , helping to provide a conceptual framework for political movements of the 18th and 19th centuries such as Pan-Germanism and Pan-Slavism . From the 1960s, a reinterpretation of archaeological and historical evidence prompted scholars, such as Goffart and Todd, to propose new models for explaining

992-405: A compass card, which moves freely on a pivot. A lubber line , which can be a marking on the compass bowl or a small fixed needle, indicates the ship's heading on the compass card. Traditionally the card is divided into thirty-two points (known as rhumbs ), although modern compasses are marked in degrees rather than cardinal points. The glass-covered box (or bowl) contains a suspended gimbal within

1116-413: A compass, for example, certain rocks which contain magnetic minerals, like Magnetite . This is often indicated by a rock with a surface which is dark and has a metallic luster, not all magnetic mineral bearing rocks have this indication. To see if a rock or an area is causing interference on a compass, get out of the area, and see if the needle on the compass moves. If it does, it means that the area or rock

1240-819: A cosmology of seven directions. For example, among the Hopi of the Southwestern United States , the four named cardinal directions are not North, South, East and West but are the four directions associated with the places of sunrise and sunset at the winter and summer solstices. Each direction may be associated with a color, which can vary widely between nations, but which is usually one of the basic colors found in nature and natural pigments, such as black, red, white, and yellow, with occasional appearances of blue, green, or other hues. There can be great variety in color symbolism, even among cultures that are close neighbors geographically. Ten Hindu deities , known as

1364-653: A device for divination as early as the Chinese Han dynasty (since c. 206 BC), and later adopted for navigation by the Song dynasty Chinese during the 11th century. The first usage of a compass recorded in Western Europe and the Islamic world occurred around 1190. The magnetic compass is the most familiar compass type. It functions as a pointer to " magnetic north ", the local magnetic meridian, because

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1488-457: A different method. To take a map bearing or true bearing (a bearing taken in reference to true, not magnetic north) to a destination with a protractor compass , the edge of the compass is placed on the map so that it connects the current location with the desired destination (some sources recommend physically drawing a line). The orienting lines in the base of the compass dial are then rotated to align with actual or true north by aligning them with

1612-496: A few nations, notably the United States Army, continue to issue field compasses with magnetized compass dials or cards instead of needles. A magnetic card compass is usually equipped with an optical, lensatic, or prismatic sight , which allows the user to read the bearing or azimuth off the compass card while simultaneously aligning the compass with the objective (see photo). Magnetic card compass designs normally require

1736-437: A fixed point while its heading is noted by alignment with fixed points on the shore. A compass deviation card is prepared so that the navigator can convert between compass and magnetic headings. The compass can be corrected in three ways. First the lubber line can be adjusted so that it is aligned with the direction in which the ship travels, then the effects of permanent magnets can be corrected for by small magnets fitted within

1860-399: A flexible rubber diaphragm or airspace inside the capsule to allow for volume changes caused by temperature or altitude, some modern liquid compasses use smaller housings and/or flexible capsule materials to accomplish the same result. The liquid inside the capsule serves to damp the movement of the needle, reducing oscillation time and increasing stability. Key points on the compass, including

1984-580: A lodestone, which appeared in China by 1088 during the Song dynasty , as described by Shen Kuo . Dry compasses began to appear around 1300 in Medieval Europe and the Islamic world . This was supplanted in the early 20th century by the liquid-filled magnetic compass. Modern compasses usually use a magnetized needle or dial inside a capsule completely filled with a liquid (lamp oil, mineral oil, white spirits, purified kerosene, or ethyl alcohol are common). While older designs commonly incorporated

2108-405: A low-friction surface to allow it to freely pivot to align itself with the magnetic field. It is then labeled so the user can distinguish the north-pointing from the south-pointing end; in modern convention the north end is typically marked in some way. If a needle is rubbed on a lodestone or other magnet, the needle becomes magnetized. When it is inserted in a cork or piece of wood, and placed in

2232-455: A map with the latest declination information should be used. Some magnetic compasses include means to manually compensate for the magnetic declination, so that the compass shows true directions. The first compasses in ancient Han dynasty China were made of lodestone , a naturally magnetized ore of iron. The wet compass reached Southern India in the 4th century AD. Later compasses were made of iron needles, magnetized by striking them with

2356-627: A map. Other features found on modern orienteering compasses are map and romer scales for measuring distances and plotting positions on maps, luminous markings on the face or bezels, various sighting mechanisms (mirror, prism, etc.) for taking bearings of distant objects with greater precision, gimbal-mounted, "global" needles for use in differing hemispheres, special rare-earth magnets to stabilize compass needles, adjustable declination for obtaining instant true bearings without resorting to arithmetic, and devices such as inclinometers for measuring gradients. The sport of orienteering has also resulted in

2480-434: A marked line of longitude (or the vertical margin of the map), ignoring the compass needle entirely. The resulting true bearing or map bearing may then be read at the degree indicator or direction-of-travel (DOT) line, which may be followed as an azimuth (course) to the destination. If a magnetic north bearing or compass bearing is desired, the compass must be adjusted by the amount of magnetic declination before using

2604-533: A microprocessor. Often, the device is a discrete component which outputs either a digital or analog signal proportional to its orientation. This signal is interpreted by a controller or microprocessor and either used internally, or sent to a display unit. The sensor uses highly calibrated internal electronics to measure the response of the device to the Earth's magnetic field. Apart from navigational compasses, other specialty compasses have also been designed to accommodate specific uses. These include: A magnetic rod

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2728-419: A needle lock is fitted to the compass to reduce wear, operated by the folding action of the rear sight/lens holder. The use of air-filled induction compasses has declined over the years, as they may become inoperative or inaccurate in freezing temperatures or extremely humid environments due to condensation or water ingress. Some military compasses, like the U.S. M-1950 ( Cammenga 3H) military lensatic compass,

2852-514: A progressive Romanisation of barbarian society, but also an undeniable barbarisation of the Roman world." For example, the Roman Empire played a vital role in building up barbarian groups along its frontier. Propped up with imperial support and gifts, the armies of allied barbarian chieftains served as buffers against other, hostile, barbarian groups. The disintegration of Roman economic power weakened groups that had come to depend on Roman gifts for

2976-433: A result of such an accommodation and were absorbed into Latinhood. In contrast, in the east, Slavic tribes maintained a more "spartan and egalitarian" existence bound to the land "even in times when they took their part in plundering Roman provinces". Their organizational models were not Roman, and their leaders were not normally dependent on Roman gold for success. Thus they arguably had a greater effect on their region than

3100-403: A separate magnetized needle inside a rotating capsule, an orienting "box" or gate for aligning the needle with magnetic north, a transparent base containing map orienting lines, and a bezel (outer dial) marked in degrees or other units of angular measurement. The capsule is mounted in a transparent baseplate containing a direction-of-travel (DOT) indicator for use in taking bearings directly from

3224-469: A separate protractor tool in order to take bearings directly from a map. The U.S. M-1950 military lensatic compass does not use a liquid-filled capsule as a damping mechanism, but rather electromagnetic induction to control oscillation of its magnetized card. A "deep-well" design is used to allow the compass to be used globally with a card tilt of up to 8 degrees without impairing accuracy. As induction forces provide less damping than fluid-filled designs,

3348-753: A small sliding counterweight installed on the needle. This sliding counterweight, called a "rider", can be used for counterbalancing the needle against the dip caused by inclination if the compass is taken to a zone with a higher or lower dip. Like any magnetic device, compasses are affected by nearby ferrous materials, as well as by strong local electromagnetic forces. Compasses used for wilderness land navigation should not be used in proximity to ferrous metal objects or electromagnetic fields (car electrical systems, automobile engines, steel pitons , etc.) as that can affect their accuracy. Compasses are particularly difficult to use accurately in or near trucks, cars or other mechanized vehicles even when corrected for deviation by

3472-471: A special word: tenggara . Sanskrit and other Indian languages that borrow from it use the names of the gods associated with each direction : east (Indra), southeast (Agni), south (Yama/Dharma), southwest (Nirrti), west (Varuna), northwest (Vayu), north (Kubera/Heaven) and northeast (Ishana/Shiva). North is associated with the Himalayas and heaven while the south is associated with the underworld or land of

3596-577: A terrestrial map because one is looking up instead of down. Similarly, when describing the location of one astronomical object relative to another, "north" means closer to the North celestial pole, "east" means at a higher right ascension , "south" means closer to the South celestial pole, and "west" means at a lower right ascension. If one is looking at two stars that are below the North Star, for example,

3720-451: A total of 32 named points evenly spaced around the compass: north (N), north by east (NbE), north-northeast (NNE), northeast by north (NEbN), northeast (NE), northeast by east (NEbE), east-northeast (ENE), east by north (EbN), east (E), etc. Cardinal directions or cardinal points may sometimes be extended to include vertical position ( elevation , altitude , depth ): north and south , east and west , up and down; or mathematically

3844-467: Is 100 grads to give a circle of 400 grads. Dividing grads into tenths to give a circle of 4000 decigrades has also been used in armies. Most military forces have adopted the French " millieme " system. This is an approximation of a milli-radian (6283 per circle), in which the compass dial is spaced into 6400 units or "mils" for additional precision when measuring angles, laying artillery, etc. The value to

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3968-471: Is a German word, borrowed from German historiography, that refers to the early migrations of the Germanic peoples. In a broader sense it can mean the mass migration of whole tribes or ethnic groups. Rather than "invasion", German and Slavic scholars speak of "migration" (see German : Völkerwanderung , Czech : Stěhování národů , Swedish : folkvandring and Hungarian : népvándorlás ), aspiring to

4092-415: Is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose , which can pivot to align itself with magnetic north . Other methods may be used, including gyroscopes, magnetometers , and GPS receivers. Compasses often show angles in degrees: north corresponds to 0°, and

4216-409: Is called a secondary intercardinal direction. These eight shortest points in the compass rose shown to the right are: Points between the cardinal directions form the points of the compass . Arbitrary horizontal directions may be indicated by their azimuth angle value. The directional names are routinely associated with azimuths , the angle of rotation (in degrees ) in the unit circle over

4340-412: Is carrying an electric current. Magnetic compasses are prone to errors in the neighborhood of such bodies. Some compasses include magnets which can be adjusted to compensate for external magnetic fields, making the compass more reliable and accurate. A compass is also subject to errors when the compass is accelerated or decelerated in an airplane or automobile. Depending on which of the Earth's hemispheres

4464-408: Is defined as the angle between the direction of true (geographic) north and the direction of the meridian between the magnetic poles. Variation values for most of the oceans had been calculated and published by 1914. Deviation refers to the response of the compass to local magnetic fields caused by the presence of iron and electric currents; one can partly compensate for these by careful location of

4588-420: Is enough to protect from walking in a substantially different direction than expected over short distances, provided the terrain is fairly flat and visibility is not impaired. By carefully recording distances (time or paces) and magnetic bearings traveled, one can plot a course and return to one's starting point using the compass alone. Compass navigation in conjunction with a map ( terrain association ) requires

4712-649: Is partly documented by Greek and Latin historians but is difficult to verify archaeologically. It puts Germanic peoples in control of most areas of what was then the Western Roman Empire . The Tervingi crossed the Danube into Roman territory in 376, in a migration fleeing the invading Huns . Some time later in Marcianopolis , the escort to their leader Fritigern was killed while meeting with Roman commander Lupicinus . The Tervingi rebelled, and

4836-509: Is related to I Ching , the Wu Xing and the five naked-eye planets . In traditional Chinese astrology , the zodiacal belt is divided into the four constellation groups corresponding to the directions. Each direction is often identified with a color, and (at least in China) with a mythological creature of that color . Geographical or ethnic terms may contain the name of the color instead of

4960-404: Is required when constructing a compass. This can be created by aligning an iron or steel rod with Earth's magnetic field and then tempering or striking it. However, this method produces only a weak magnet so other methods are preferred. For example, a magnetised rod can be created by repeatedly rubbing an iron rod with a magnetic lodestone . This magnetised rod (or magnetic needle) is then placed on

5084-732: Is similar to a gyroscope . It is a non-magnetic compass that finds true north by using an (electrically powered) fast-spinning wheel and friction forces in order to exploit the rotation of the Earth. Gyrocompasses are widely used on ships . They have two main advantages over magnetic compasses: Large ships typically rely on a gyrocompass, using the magnetic compass only as a backup. Increasingly, electronic fluxgate compasses are used on smaller vessels. However, magnetic compasses are still widely in use as they can be small, use simple reliable technology, are comparatively cheap, are often easier to use than GPS , require no energy supply, and unlike GPS, are not affected by objects, e.g. trees, that can block

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5208-587: Is the interesting situation that native Japanese words ( yamato kotoba , kun readings of kanji) are used for the cardinal directions (such as minami for 南, south), but borrowed Chinese words (on readings of kanji) are used for intercardinal directions (such as tō-nan for 東南, southeast, lit. "east-south"). In the Malay language , adding laut (sea) to either east ( timur ) or west ( barat ) results in northeast or northwest, respectively, whereas adding daya to west (giving barat daya ) results in southwest. Southeast has

5332-454: Is the magnetic bearing to the target. Again, if one is using "true" or map bearings, and the compass does not have preset, pre-adjusted declination, one must additionally add or subtract magnetic declination to convert the magnetic bearing into a true bearing . The exact value of the magnetic declination is place-dependent and varies over time, though declination is frequently given on the map itself or obtainable on-line from various sites. If

5456-487: Is used for the center. All five are used for geographic subdivision names ( wilayahs , states, regions, governorates, provinces, districts or even towns), and some are the origin of some Southern Iberian place names (such as Algarve , Portugal and Axarquía , Spain). In Mesoamerica and North America , a number of traditional indigenous cosmologies include four cardinal directions and a center. Some may also include "above" and "below" as directions, and therefore focus on

5580-476: The Völkerwanderung may illustrate such [a] course of events, but it misleads. Unfolded over long periods of time, the changes of position that took place were necessarily irregular ... (with) periods of emphatic discontinuity. For decades and possibly centuries, the tradition bearers idled, and the tradition itself hibernated. There was ample time for forgetfulness to do its work. Völkerwanderung

5704-701: The Brittonic chieftains (whose centres of power retreated westward as a result). The Eastern Roman Empire attempted to maintain control of the Balkan provinces despite a thinly-spread imperial army relying mainly on local militias and an extensive effort to refortify the Danubian limes . The ambitious fortification efforts collapsed, worsening the impoverished conditions of the local populace and resulting in colonization by Slavic warriors and their families. Halsall and Noble have argued that such changes stemmed from

5828-482: The Northern Hemisphere , to zone 5 covering Australia and the southern oceans. This individual zone balancing prevents excessive dipping of one end of the needle, which can cause the compass card to stick and give false readings. Some compasses feature a special needle balancing system that will accurately indicate magnetic north regardless of the particular magnetic zone. Other magnetic compasses have

5952-663: The Ostrogoths , led by Theodoric the Great , who settled in Italy. In Gaul , the Franks (a fusion of western Germanic tribes whose leaders had been aligned with Rome since the 3rd century) entered Roman lands gradually during the 5th century, and after consolidating power under Childeric and his son Clovis's decisive victory over Syagrius in 486, established themselves as rulers of northern Roman Gaul. Fending off challenges from

6076-516: The Silva 4b Militaire , and the Suunto M-5N(T) contain the radioactive material tritium ( 1 H ) and a combination of phosphors. The U.S. M-1950 equipped with self-luminous lighting contains 120 mCi (millicuries) of tritium. The purpose of the tritium and phosphors is to provide illumination for the compass, via radioluminescent tritium illumination , which does not require

6200-1004: The Vikings , the Normans , the Varangians , the Hungarians , the Arabs , the Turks , and the Mongols also had significant effects (especially in North Africa , the Iberian Peninsula , Anatolia and Central and Eastern Europe ). Germanic peoples moved out of southern Scandinavia and northern Germany to the adjacent lands between the Elbe and Oder after 1000 BC. The first wave moved westward and southward (pushing

6324-545: The horizontal plane . It is a necessary step for navigational calculations (derived from trigonometry ) and for use with Global Positioning System (GPS) receivers . The four cardinal directions correspond to the following degrees of a compass: The intercardinal (intermediate, or, historically, ordinal) directions are the four intermediate compass directions located halfway between each pair of cardinal directions. These eight directional names have been further compounded known as tertiary intercardinal directions, resulting in

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6448-458: The magnetized needle at its heart aligns itself with the horizontal component of the Earth's magnetic field . The magnetic field exerts a torque on the needle, pulling the North end or pole of the needle approximately toward the Earth's North magnetic pole , and pulling the other toward the Earth's South magnetic pole . The needle is mounted on a low-friction pivot point, in better compasses

6572-527: The " Dikpālas ", have been recognized in classical Indian scriptures, symbolizing the four cardinal and four intercardinal directions with the additional directions of up and down . Each of the ten directions has its own name in Sanskrit . Some indigenous Australians have cardinal directions deeply embedded in their culture. For example, the Warlpiri people have a cultural philosophy deeply connected to

6696-626: The 6th century. They were later followed by the Bavarians and the Franks, who conquered and ruled most of the Italian peninsula. The Bulgars, originally a nomadic group probably from Central Asia , occupied the Pontic steppe north of Caucasus from the 2nd century. Later, pushed by the Khazars , the majority of them migrated west and dominated Byzantine territories along the lower Danube in

6820-653: The 7th century. From that time the demographic picture of the Balkans changed permanently, becoming predominantly Slavic-speaking, while pockets of native people survived in the mountains of the Balkans. Croats settled in modern Croatia and Western Bosnia, bringing with them the Serbs who settled in Rascia, an area around Montenegro - South-West Serbia. By the mid seventh century, Serb tribes were invading northern Albania. By

6944-628: The Alemanni, Burgundians, and Visigoths, the Frankish kingdom became the nucleus of what would later become France and Germany. The initial Anglo-Saxon settlement of Britain occurred during the 5th century, when Roman control of Britain had come to an end. The Burgundians settled in northwestern Italy, Switzerland and Eastern France in the 5th century. Between AD 500 and 700, Slavic tribes settled more areas of central Europe and pushed farther into southern and eastern Europe, gradually making

7068-861: The Bulgars. During the Khazar–Arab Wars , the Khazars stopped the Arab expansion into Europe across the Caucasus (7th and 8th centuries). At the same time, the so-called Moors (consisting of Arabs and Berbers ) invaded Europe via Gibraltar ( conquering Hispania from the Visigothic Kingdom in 711), before being halted by the Franks at the Battle of Tours in Gaul. These campaigns led to broadly demarcated frontiers between Christendom and Islam for

7192-730: The Earth's magnetic field. Additionally, compared with gyrocompasses, they are much cheaper, they work better in polar regions, they are less prone to be affected by mechanical vibration, and they can be initialized far more quickly. However, they depend on the functioning of, and communication with, the GPS satellites, which might be disrupted by an electronic attack or by the effects of a severe solar storm. Gyrocompasses remain in use for military purposes (especially in submarines, where magnetic and GPS compasses are useless), but have been largely superseded by GPS compasses, with magnetic backups, in civilian contexts. Migration Period The term refers to

7316-491: The Germanic names for the intermediate directions. Medieval Scandinavian orientation would thus have involved a 45 degree rotation of cardinal directions. In many regions of the world, prevalent winds change direction seasonally, and consequently many cultures associate specific named winds with cardinal and intercardinal directions. For example, classical Greek culture characterized these winds as Anemoi . In pre-modern Europe more generally, between eight and 32 points of

7440-522: The Goths, the Franks or the Saxons had on theirs. Based on the belief that particular types of artifacts, elements of personal adornment generally found in a funerary context, are thought to indicate the ethnicity of the person buried, the "Culture-History" school of archaeology assumed that archaeological cultures represent the Urheimat (homeland) of tribal polities named in historical sources. As

7564-508: The North celestial pole. Similarly, a line from the center to the South celestial pole will define the South point by its intersection with the limb. The points at right angles to the North and South points are the East and West points. Going around the disk clockwise from the North point, one encounters in order the West point, the South point, and then the East point. This is opposite to the order on

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7688-704: The Roman Balkans , and the Franks were settled south of the Rhine in Roman Gaul . In 406 a particularly large and unexpected crossing of the Rhine was made by a group of Vandals , Alans and Suebi . As central power broke down in the Western Roman Empire, the military became more important but was dominated by men of barbarian origin. There are contradictory opinions as to whether the fall of

7812-1012: The Roman Empire at that time. The first migrations of peoples were made by Germanic tribes such as the Goths (including the Visigoths and the Ostrogoths ), the Vandals, the Anglo-Saxons , the Lombards, the Suebi, the Frisii , the Jutes , the Burgundians , the Alemanni, the Sciri and the Franks; they were later pushed westward by the Huns, the Avars, the Slavs and the Bulgars. Later invasions, such as

7936-667: The Roman Empire in both its western and its eastern portions. In particular, economic fragmentation removed many of the political, cultural and economic forces that had held the empire together. The rural population in Roman provinces became distanced from the metropolis, and there was little to differentiate them from other peasants across the Roman frontier. In addition, Rome increasingly used foreign mercenaries to defend itself. That "barbarisation" parallelled changes within Barbaricum . To this end, noted linguist Dennis Howard Green wrote, "the first centuries of our era witness not merely

8060-575: The Roman West and Byzantium gradually converted the non-Islamic newcomers and integrated them into Christendom. Analysis of barbarian identity and how it was created and expressed during the Barbarian Invasions has elicited discussion among scholars. Herwig Wolfram , a historian of the Goths, in discussing the equation of migratio gentium with Völkerwanderung , observes that Michael Schmidt  [ de ] introduced

8184-654: The Visigoths, a group derived either from the Tervingi or from a fusion of mainly Gothic groups, eventually invaded Italy and sacked Rome in 410 before settling in Gaul. Around 460, they founded the Visigothic Kingdom in Iberia. They were followed into Roman territory first by a confederation of Herulian , Rugian , and Scirian warriors under Odoacer , that deposed Romulus Augustulus in 476, and later by

8308-424: The Western Roman Empire was a result of an increase in migrations, or if both the breakdown of central power and the increased importance of non-Romans created additional internal factors. Migrations, and the use of non-Romans in the military, were known in the periods before and after, and the Eastern Roman Empire adapted and continued to exist until the fall of Constantinople to the Ottomans in 1453. The fall of

8432-431: The Western Roman Empire, although it involved the establishment of competing barbarian kingdoms, was to some extent managed by the Eastern emperors. The migrants comprised war bands or tribes of 10,000 to 20,000 people. Immigration was common throughout the time of the Roman Empire, but over the course of 100 years, the migrants numbered not more than 750,000 in total, compared to an average 40 million population of

8556-404: The angles increase clockwise , so east is 90°, south is 180°, and west is 270°. These numbers allow the compass to show azimuths or bearings which are commonly stated in degrees. If local variation between magnetic north and true north is known, then direction of magnetic north also gives direction of true north. Among the Four Great Inventions , the magnetic compass was first invented as

8680-410: The baseplate. To check one's progress along a course or azimuth, or to ensure that the object in view is indeed the destination, a new compass reading may be taken to the target if visible (here, the large mountain). After pointing the DOT arrow on the baseplate at the target, the compass is oriented so that the needle is superimposed over the orienting arrow in the capsule. The resulting bearing indicated

8804-489: The bearing so that both map and compass are in agreement. In the given example, the large mountain in the second photo was selected as the target destination on the map. Some compasses allow the scale to be adjusted to compensate for the local magnetic declination; if adjusted correctly, the compass will give the true bearing instead of the magnetic bearing. The modern hand-held protractor compass always has an additional direction-of-travel (DOT) arrow or indicator inscribed on

8928-429: The breakdown in Roman political control, which exposed the weakness of local Roman rule. Instead of large-scale migrations, there were military takeovers by small groups of warriors and their families, who usually numbered only in the tens of thousands. The process involved active, conscious decision-making by Roman provincial populations. The collapse of centralized control severely weakened the sense of Roman identity in

9052-414: The cardinal directions can be calculated. Manufactured primarily for maritime and aviation applications, they can also detect pitch and roll of ships. Small, portable GPS receivers with only a single antenna can also determine directions if they are being moved, even if only at walking pace. By accurately determining its position on the Earth at times a few seconds apart, the device can calculate its speed and

9176-442: The case of the compass. The effect of ferromagnetic materials in the compass's environment can be corrected by two iron balls mounted on either side of the compass binnacle in concert with permanent magnets and a Flinders bar . The coefficient a 0 {\displaystyle a_{0}} represents the error in the lubber line, while a 1 , b 1 {\displaystyle a_{1},b_{1}}

9300-415: The center as a fifth cardinal point . Central Asian , Eastern European and North East Asian cultures frequently have traditions associating colors with four or five cardinal points. Systems with five cardinal points (four directions and the center) include those from pre-modern China , as well as traditional Turkic , Tibetan and Ainu cultures. In Chinese tradition, the five cardinal point system

9424-678: The compass – cardinal and intercardinal directions – were given names. These often corresponded to the directional winds of the Mediterranean Sea (for example, southeast was linked to the Sirocco , a wind from the Sahara). Particular colors are associated in some traditions with the cardinal points. These are typically " natural colors " of human perception rather than optical primary colors . Many cultures, especially in Asia , include

9548-749: The compass and the placement of compensating magnets under the compass itself. Mariners have long known that these measures do not completely cancel deviation; hence, they performed an additional step by measuring the compass bearing of a landmark with a known magnetic bearing. They then pointed their ship to the next compass point and measured again, graphing their results. In this way, correction tables could be created, which would be consulted when compasses were used when traveling in those locations. Mariners are concerned about very accurate measurements; however, casual users need not be concerned with differences between magnetic and true North. Except in areas of extreme magnetic declination variance (20 degrees or more), this

9672-407: The compass card. For a table of the thirty-two points, see compass points . In the modern era, the 360-degree system took hold. This system is still in use today for civilian navigators. The degree system spaces 360 equidistant points located clockwise around the compass dial. In the 19th century some European nations adopted the " grad " (also called grade or gon) system instead, where a right angle

9796-721: The compass directions is common and deeply embedded in European and Chinese culture (see south-pointing chariot ). Some other cultures make greater use of other referents, such as toward the sea or toward the mountains ( Hawaii , Bali ), or upstream and downstream (most notably in ancient Egypt , also in the Yurok and Karuk languages). Lengo (Guadalcanal, Solomon Islands) has four non-compass directions: landward, seaward, upcoast, and downcoast. Some languages lack words for body-relative directions such as left/right, and use geographical directions instead. Compass A compass

9920-409: The compass is located and if the force is acceleration or deceleration the compass will increase or decrease the indicated heading. Compasses that include compensating magnets are especially prone to these errors, since accelerations tilt the needle, bringing it closer or further from the magnets. Another error of the mechanical compass is the turning error. When one turns from a heading of east or west

10044-451: The compass is located on the surface of the Earth the angle between true 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 compass parallel to true north. The locations of the Earth's magnetic poles slowly change with time, which is referred to as geomagnetic secular variation . The effect of this means

10168-400: The compass to be "recharged" by sunlight or artificial light. However, tritium has a half-life of only about 12 years, so a compass that contains 120 mCi of tritium when new will contain only 60 when it is 12 years old, 30 when it is 24 years old, and so on. Consequently, the illumination of the display will fade. Mariners' compasses can have two or more magnets permanently attached to

10292-400: The compass was previously at is causing interference and should be avoided. There are other ways to find north than the use of magnetism, and from a navigational point of view a total of seven possible ways exist (where magnetism is one of the seven). Two sensors that use two of the remaining six principles are often also called compasses, i.e. the gyrocompass and GPS-compass. A gyrocompass

10416-410: The compass will lag behind the turn or lead ahead of the turn. Magnetometers, and substitutes such as gyrocompasses, are more stable in such situations. A thumb compass is a type of compass commonly used in orienteering , a sport in which map reading and terrain association are paramount. Consequently, most thumb compasses have minimal or no degree markings at all, and are normally used only to orient

10540-552: The construction of barbarian identity. They maintained that no sense of shared identity was perceived by the Germani ; a similar theory having been proposed for Celtic and Slavic groups. A theory states that the primordialist mode of thinking was encouraged by a prima facie interpretation of Graeco-Roman sources, which grouped together many tribes under such labels as Germanoi , Keltoi or Sclavenoi , thus encouraging their perception as distinct peoples. Modernists argue that

10664-409: The correct local compass variation so as to indicate the true heading. ‹The template How-to is being considered for merging .›   A magnetic compass points to magnetic north pole, which is approximately 1,000 miles from the true geographic North Pole. A magnetic compass's user can determine true North by finding the magnetic north and then correcting for variation and deviation. Variation

10788-477: The dates for the beginning and ending of the Migration Period. The beginning of the period is widely regarded as the invasion of Europe by the Huns from Asia in about 375 and the ending with the conquest of Italy by the Lombards in 568, but a more loosely set period is from as early as 300 to as late as 800. For example, in the 4th century a very large group of Goths was settled as foederati within

10912-425: The development of models with extremely fast-settling and stable needles utilizing rare-earth magnets for optimal use with a topographic map , a land navigation technique known as terrain association . Many marine compasses designed for use on boats with constantly shifting angles use dampening fluids such as isopar M or isopar L to limit the rapid fluctuation and direction of the needle. The military forces of

11036-524: The eastern half of Europe predominantly Slavic-speaking. Additionally, Turkic tribes such as the Avars and - later - Ugric-speaking Magyars became involved in this second wave. In AD 567, the Avars and the Lombards destroyed much of the Gepid Kingdom . The Lombards, a Germanic people, settled in Italy with their Herulian, Suebian, Gepid, Thuringian, Bulgar, Sarmatian and Saxon allies in

11160-657: The equation in his 1778 history of the Germans. Wolfram observed that the significance of gens as a biological community was shifting, even during the early Middle Ages and that "to complicate matters, we have no way of devising a terminology that is not derived from the concept of nationhood created during the French Revolution ". The "primordialistic" paradigm prevailed during the 19th century. Scholars, such as German linguist Johann Gottfried Herder , viewed tribes as coherent biological (racial) entities, using

11284-602: The fathers (Pitr loka). The directions are named by adding "disha" to the names of each god or entity: e.g. Indradisha (direction of Indra) or Pitrdisha (direction of the forefathers i.e. south). The cardinal directions of the Hopi language and the Tewa dialect spoken by the Hopi-Tewa are related to the places of sunrise and sunset at the solstices, and correspond approximately to the European intercardinal directions. Use of

11408-463: The ferromagnetic effects and a 2 , b 2 {\displaystyle a_{2},b_{2}} the non-ferromagnetic component. A similar process is used to calibrate the compass in light general aviation aircraft, with the compass deviation card often mounted permanently just above or below the magnetic compass on the instrument panel. Fluxgate electronic compasses can be calibrated automatically, and can also be programmed with

11532-530: The four cardinal directions and the Guugu Yimithirr people use cardinal directions rather than relative direction even when indicating the position of an object close to their body. (For more information, see: Cultures without relative directions .) The precise direction of the cardinal points appears to be important in Aboriginal stone arrangements . Many aboriginal languages contain words for

11656-420: The hiker has been following the correct path, the compass' corrected (true) indicated bearing should closely correspond to the true bearing previously obtained from the map. A compass should be laid down on a level surface so that the needle only rests or hangs on the bearing fused to the compass casing – if used at a tilt, the needle might touch the casing on the compass and not move freely, hence not pointing to

11780-446: The idea of "imagined communities"; the barbarian polities in late antiquity were social constructs rather than unchanging lines of blood kinship. The process of forming tribal units was called " ethnogenesis ", a term coined by Soviet scholar Yulian Bromley . The Austrian school (led by Reinhard Wenskus ) popularized this idea, which influenced medievalists such as Herwig Wolfram, Walter Pohl and Patrick J. Geary . It argues that

11904-437: The idea of a dynamic and "wandering Indo-Germanic people". In contrast, the standard terms in French and Italian historiography translate to "barbarian invasions", or even "barbaric invasions" ( French : Invasions barbares , Italian : Invasioni barbariche ). Historians have postulated several explanations for the appearance of "barbarians" on the Roman frontier: climate change, weather and crops, population pressure ,

12028-459: The identity of the newcomers. In Gaul , the collapse of imperial rule resulted in anarchy: the Franks and Alemanni were pulled into the ensuing "power vacuum", resulting in conflict. In Hispania, local aristocrats maintained independent rule for some time, raising their own armies against the Vandals . Meanwhile, the Roman withdrawal from lowland England resulted in conflict between Saxons and

12152-681: The important role played by the migration, invasion, and settlement of various tribes, notably the Burgundians , Vandals , Goths , Alemanni , Alans , Huns , early Slavs , Pannonian Avars , Bulgars and Magyars within or into the territories of the Roman Empire and Europe as a whole. The period is traditionally taken to have begun in AD ;375 (possibly as early as 300) and ended in 568. Various factors contributed to this phenomenon of migration and invasion, and their role and significance are still widely discussed. Historians differ as to

12276-536: The magnetic north accurately, giving a faulty reading. To see if the needle is well leveled, look closely at the needle, and tilt it slightly to see if the needle is swaying side to side freely and the needle is not contacting the casing of the compass. If the needle tilts to one direction, tilt the compass slightly and gently to the opposing direction until the compass needle is horizontal, lengthwise. Items to avoid around compasses are magnets of any kind and any electronics. Magnetic fields from electronics can easily disrupt

12400-647: The magnetic pole the compass will not indicate any particular direction but will begin to drift. Also, the needle starts to point up or down when getting closer to the poles, because of the so-called magnetic inclination . Cheap compasses with bad bearings may get stuck because of this and therefore indicate a wrong direction. Magnetic compasses are influenced by any fields other than Earth's. Local environments may contain magnetic mineral deposits and artificial sources such as MRIs , large iron or steel bodies, electrical engines or strong permanent magnets. Any electrically conductive body produces its own magnetic field when it

12524-471: The maintenance of their own power. The arrival of the Huns helped prompt many groups to invade the provinces for economic reasons. The nature of the barbarian takeover of former Roman provinces varied from region to region. For example, in Aquitaine , the provincial administration was largely self-reliant. Halsall has argued that local rulers simply "handed over" military rule to the Ostrogoths , acquiring

12648-418: The map to magnetic north. An oversized rectangular needle or north indicator aids visibility. Thumb compasses are also often transparent so that an orienteer can hold a map in the hand with the compass and see the map through the compass. The best models use rare-earth magnets to reduce needle settling time to 1 second or less. The earth inductor compass (or "induction compass") determines directions using

12772-415: The military is that one angular mil subtends approximately one metre at a distance of one kilometer. Imperial Russia used a system derived by dividing the circumference of a circle into chords of the same length as the radius. Each of these was divided into 100 spaces, giving a circle of 600. The Soviet Union divided these into tenths to give a circle of 6000 units, usually translated as "mils". This system

12896-420: The name of the corresponding direction. East: Green ( 青 "qīng" corresponds to both green and blue); Spring; Wood South: Red ; Summer; Fire West: White ; Autumn; Metal North: Black ; Winter; Water Center: Yellow ; Earth Countries where Arabic is used refer to the cardinal directions as Ash Shamal (N), Al Gharb (W), Ash Sharq (E) and Al Janoob (S). Additionally, Al Wusta

13020-465: The needle, preventing it from aligning with the Earth's magnetic fields, causing inaccurate readings. The Earth's natural magnetic forces are considerably weak, measuring at 0.5 gauss and magnetic fields from household electronics can easily exceed it, overpowering the compass needle. Exposure to strong magnets, or magnetic interference can sometimes cause the magnetic poles of the compass needle to differ or even reverse. Avoid iron rich deposits when using

13144-649: The next millennium. The following centuries saw the Muslims successful in conquering most of Sicily from the Christians by 902. The Hungarian conquest of the Carpathian Basin from around AD 895 and the subsequent Hungarian invasions of Europe and the Viking expansion from the late 8th century conventionally mark the last large migration movements of the period. Christian missionaries from Ireland,

13268-430: The ninth century, the central Balkans (corresponding to modern Kosovo, Serbia and Macedonia) and the area of southern and central Albania became invaded and settled by Bulgars. During the early Byzantine–Arab Wars , Arab armies attempted to invade southeast Europe via Asia Minor during the late 7th and early 8th centuries but were defeated at the siege of Constantinople (717–718) by the joint forces of Byzantium and

13392-534: The north end of the needle are often marked with phosphorescent , photoluminescent , or self-luminous materials to enable the compass to be read at night or in poor light. As the compass fill liquid is noncompressible under pressure, many ordinary liquid-filled compasses will operate accurately underwater to considerable depths. Many modern compasses incorporate a baseplate and protractor tool, and are referred to variously as " orienteering ", "baseplate", "map compass" or "protractor" designs. This type of compass uses

13516-628: The one that is "east" will actually be further to the left. During the Migration Period , the Germanic names for the cardinal directions entered the Romance languages , where they replaced the Latin names borealis (or septentrionalis ) with north, australis (or meridionalis ) with south, occidentalis with west and orientalis with east. It is possible that some northern people used

13640-726: The opposite coast of the Baltic Sea , moving up the Vistula near the Carpathian Mountains . During Tacitus ' era they included lesser-known tribes such as the Tencteri , Cherusci , Hermunduri and Chatti ; however, a period of federation and intermarriage resulted in the familiar groups known as the Alemanni , Franks , Saxons , Frisians and Thuringians . The first wave of invasions, between AD 300 and 500,

13764-502: The politics of an empire already falling apart for quite a few other causes". Goffart argues that the process of settlement was connected to hospitalitas , the Roman practice of quartering soldiers among the civilian population. The Romans, by granting land and the right to levy taxes to allied (Germanic) armies, hoped to reduce the financial burdens of the empire. The Crisis of the Third Century caused significant changes within

13888-464: The principle of electromagnetic induction , with the Earth's magnetic field acting as the induction field for an electric generator , the measurable output of which varies depending on orientation . Small electronic compasses ( eCompasses ) found in clocks, mobile phones , and other electronic devices are solid-state microelectromechanical systems (MEMS) compasses, usually built out of two or three magnetic field sensors that provide data for

14012-422: The provinces, which may explain why the provinces then underwent dramatic cultural changes even though few barbarians settled in them. Ultimately, the Germanic groups in the Western Roman Empire were accommodated without "dispossessing or overturning indigenous society", and they maintained a structured and hierarchical (but attenuated) form of Roman administration. Ironically, they lost their unique identity as

14136-401: The reception of electronic signals. GPS receivers using two or more antennae mounted separately and blending the data with an inertial motion unit (IMU) can now achieve 0.02° in heading accuracy and have startup times in seconds rather than hours for gyrocompass systems. The devices accurately determine the positions (latitudes, longitudes and altitude) of the antennae on the Earth, from which

14260-482: The resident Celts west to the Rhine around 200 BC), moving into southern Germany up to the Roman provinces of Gaul and Cisalpine Gaul by 100 BC, where they were stopped by Gaius Marius and later by Julius Caesar . It is this western group which was described by the Roman historian Tacitus (AD 56–117) and Julius Caesar (100–44 BC). A later wave of Germanic tribes migrated eastward and southward from Scandinavia, between 600 and 300 BC, to

14384-404: The six directions of the x-, y-, and z-axes in three-dimensional Cartesian coordinates . Topographic maps include elevation, typically via contour lines . Alternatively, elevation angle may be combined with cardinal direction (or, more generally, arbitrary azimuth angle) to form a local spherical coordinate system . In astronomy , the cardinal points of an astronomical body as seen in

14508-451: The sky are four points defined by the directions toward which the celestial poles lie relative to the center of the disk of the object in the sky. A line (a great circle on the celestial sphere ) from the center of the disk to the North celestial pole will intersect the edge of the body (the " limb ") at the North point. The North point will then be the point on the limb that is closest to

14632-511: The stimulus for forming tribal polities was perpetuated by a small nucleus of people, known as the Traditionskern ("kernel of tradition"), who were a military or aristocratic elite. This core group formed a standard for larger units, gathering adherents by employing amalgamative metaphors such as kinship and aboriginal commonality and claiming that they perpetuated an ancient, divinely-sanctioned lineage. The common, track-filled map of

14756-475: The term to refer to discrete ethnic groups. He also believed that the Volk were an organic whole, with a core identity and spirit evident in art, literature and language. These characteristics were seen as intrinsic, unaffected by external influences, even conquest. Language, in particular, was seen as the most important expression of ethnicity. They argued that groups sharing the same (or similar) language possessed

14880-479: The true bearing (relative to true north ) of its direction of motion. Frequently, it is preferable to measure the direction in which a vehicle is actually moving, rather than its heading, i.e. the direction in which its nose is pointing. These directions may be different if there is a crosswind or tidal current. GPS compasses share the main advantages of gyrocompasses. They determine true North, as opposed to magnetic North, and they are unaffected by perturbations of

15004-454: The uniqueness perceived by specific groups was based on common political and economic interests rather than biological or racial distinctions. Indeed, on this basis, some schools of thought in recent scholarship urge that the concept of Germanic peoples be jettisoned altogether. The role of language in constructing and maintaining group identity can be ephemeral since large-scale language shifts occur commonly in history. Modernists propose

15128-407: The use of built-in magnets or other devices. Large amounts of ferrous metal combined with the on-and-off electrical fields caused by the vehicle's ignition and charging systems generally result in significant compass errors. At sea, a ship's compass must also be corrected for errors, called deviation , caused by iron and steel in its structure and equipment. The ship is swung , that is rotated about

15252-622: The usual four cardinal directions, but some contain words for 5 or even 6 cardinal directions. In some languages , such as Estonian , Finnish and Breton , the intercardinal directions have names that are not compounds of the names of the cardinal directions (as, for instance, northeast is compounded from north and east ). In Estonian, those are kirre (northeast), kagu (southeast), edel (southwest), and loe (northwest), in Finnish koillinen (northeast), kaakko (southeast), lounas (southwest), and luode (northwest). In Japanese, there

15376-618: Was adopted by the former Warsaw Pact countries, e.g. , the Soviet Union, East Germany , etc., often counterclockwise (see picture of wrist compass). This is still in use in Russia. Because the Earth's magnetic field's inclination and intensity vary at different latitudes, compasses are often balanced during manufacture so that the dial or needle will be level, eliminating needle drag. Most manufacturers balance their compass needles for one of five zones, ranging from zone 1, covering most of

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