Compass
The Compass (plural compasses, see the relevant section; origin: Italian com - passo = the order - stepping, the Zirkelweg ) is an instrument for determining a fixed predetermined direction, such as the compass, navigation course, bearing direction. The oldest version is the rear sight, which allows to align with the polar star on a clear night. The classic device is the magnetic compass, which allows the determination of magnetic north and from all other directions using the Earth's magnetic field. Other designs are electronic compasses based on Hall sensors or fluxgate magnetometers; with the latter amount and direction of the geomagnetic field on a 1/100.000 the absolute value can be accurately determined.
Without utilization of the geomagnetic field work gyros that are not identified as a result of their action, the direction with respect to the geographic north-south direction and relative to the position of the magnetic poles of the earth.
Also without a magnetic field coming from the sun compasses.
A compass with direction-finding device is also called a compass. Mostly this term is used in surveying technology for precision bearing compasses, especially in Austria and Italy, but also the simple marching compass is so named.
History
The compass complements the navigation based on stars, landmarks, the depth of the sea by means of sounding, swell and current, wind, water temperature, color and taste, animals, clouds and other features.
The realization that rotate splinter of loadstone in the north-south direction (time between 475 BC and 221 BC) was in Europe since the Greek Antiquity and in China since the time of the Warring known. The Chinese used since the 11th century, a floating compass needle ( wet compass), Südweiser was called. In fact, the Chinese compass does not point north, but to the south. Over time, these developed special compass shapes with a division into 24, 32, 48 or 64 lines or directions (see Earthly Branches ). Shen Kuo describes it at the beginning of the 11th century in his major work.
In Europe, the wet compass was first around 1187 by the French monk Hugues de Bercy (also Guyot de Provins called ) in a church critical book in French (title: La Bible de Guyot, Source: COMPASSIPEDIA / Compass Museum, history / literature ), and shortly thereafter was set to Latin, hence the much greater level of awareness, the English scholar Alexander Neckam, lived at the same time in Paris and the Church to non- critical, as a magnetized needle floating above, which was in use among sailors. It's such a different views about where the origin of the compass is to be sought. The most serious studies (J. Klaproth, L. de Saussure ) lead to the conclusion that Chinese navigators already knew the wet compass around the turn of the millennium. However, the Arabs did not need the compass, as they already had excellent astronomical knowledge and were able to navigate well through consistent winds. The sailors of the eastern Mediterranean have experienced no later than the time of the Crusades from this instrument navigation and improved it. However, since on the one hand great advantages over the competition brought its owner and on the other hand worked with virtually prohibited magical powers, it was kept as secret as possible. Published in 1932 by E. Lippman, a study in which he tried to prove the alleged superiority of the " Nordic race " by. Arguments for a hypothetical, independent invention of the compass in Europe without going into all the other previous studies This erroneous theory is unfortunately still today represented here and there Among the Arabs can indeed prove mention the wet compass hundred years after Alexander Neckams.
The first written mention of a dry gambling on a pin magnetic needle is found in the Epistola de magnets of 1269, written by Peter Peregrinus de Maricourt, which used the dry compass was invented today. As alleged inventor applies an Italian navigator from Amalfi, where even today Flavio Gioia is honored as the "inventor of the compass " with a monument at the harbor (see legend of Flöavio de Gioia in Compass Museum. Various / history ). In the late 13th century, the sailors of the Mediterranean combined first with the magnetic needle of the compass.
Around 1400 European sailors built the dry compass and wind rose in a solid housing to get it fixed stationing on their ships. The dry compass was much more accurate than the unstable floating needle of the Chinese and so allowing better navigation. Leonardo da Vinci suggested the first to place the compass box in a cardan suspension, so as to improve the accuracy. From 1534 his idea was realized in practice and continued during the 16th century throughout Europe by, giving European sailing ships on the most advanced and most accurate compass technology of the time possessed. After China, the dry compass was about the year 1600 over Japan, which had taken him by the Spaniards and Portuguese.
The compass was also used in the mining industry as a surveying instrument (Mark Scheider). In the northern Italian mountain town of Massa compass to determine the direction of advance and avoid breakdowns between mines are occupied in the 13th and 14th centuries, and the Tyrolean mining he belonged in the second half of the 15th century to the standard equipment. The mountain book of German coal and steel scientist Ulrich Rülein of Calw can be considered a first theoretical treatise on the underground use of the compass.
Design and operation of magnetic compasses
The magnetic compass is composed of a rotatable pointer of magnetic material, and a housing in which the hand is mounted with low friction as possible. As a carrier of the magnetic needle, for example, abrasion -proof gems such as ruby and sapphire are used. On the housing or the pointer an angle scale is usually mounted. The pointer itself can have the traditional form of a needle ( compass needle ), in some newer compasses is a complete disc to find, in ship compasses usually a ball ( ball compass).
The pointer is directed, if he is free to move in all directions, in the direction of the geomagnetic field from. Its field lines in many areas of the world and especially in Central Europe about geographical north-south direction. Since the deviations can be measured very accurately and are listed, for example, in topographic maps, can be determined from the direction of the pointer relative to the geographic north exactly.
Compass capsules are usually filled with a liquid in order to dampen the movement of the needle. This makes them vibrate with less vibration, which facilitates reading and prevents errors without affecting the rapid settling is prevented. This oil is used which does not lead to rusting of the needle and does not freeze under extreme conditions.
Application
Despite the existence of the GPS of the magnetic compass is used as before. GPS navigation can complement the useful with map and compass, never replace it. In addition to the dependence on energy supply and electronics, the course angle determination is with a compass much more quickly and accurately perform as a GPS device. In addition, a compass enforces the constant confrontation with the real situation, while the GPS device easily leads to blindly rely on satellite technology.
For the navigation with map and compass now mostly a plate compass, also called Map Compass used, the housing is located in a transparent acrylic glass plate. This plate facilitates the cards work and makes it easy to bring the north-south lines of the compass to the grid of a topographic map in a match. A polar alignment of the card is not necessary.
Confusion about north or south pole
Again and again the question leads to confusion, whether in the north earth lies the magnetic north or south magnetic pole. A look at the history helps to understand the facts.
As the magnetic property of magnetite needle has been discovered called the end of the needle, the pointed north, an obvious way the north pole of the needle. It was only much later found the reason of the effect, and that always attract opposite poles with magnets. Since the designation of polarity, however, was already defined. The earth in the geographic north so a magnetic south pole.
To avoid these linguistic ambivalence in recent times are also the terms " Arctic magnetic pole " and " Antarctic magnetic pole " is used.
Division of the Compass Rose
Basically, compass roses are divided into equal sectors of a circle. The unit systems most commonly used are the degree at 360 subregions, 400 grads in subregions and for line or Mil 6400 subregions, with only the hundreds are drawn (card number). The nautical line divides the circle into 32 segments. He is no longer used today in navigation.
Declination
Since the connecting line of the magnetic poles relative to the earth's axis is tilted by about 11.5 °, the magnetic poles are currently approximately 2000 km from the geographic poles removed. The magnetic poles change their position over time because of the earth's magnetism is due to variable currents in the metallic core. In addition, the course of the magnetic field lines is influenced by local geological conditions (eg iron -bearing rock ). These two factors cause the deviation of the compass needle from true north at any location on earth is different. This deviation is called local declination or declination. It is not sure who first recognized this. However, is considered certain that Georg von Peuerbach was the first who wrote about the declination. The oldest surviving compass in which the declination is located, comes from Peuerbach. A gyrocompass has no declination.
Deviation
As deviation variations are referred to, which can be induced by magnetic fields in the vicinity of the compass. Such fields are generated by magnetic or magnetizable objects as well as by flowing direct current ( electric appliances). A possible countermeasure is to accommodate a master compass to a better location than the bridge or the cockpit of the ship or aircraft. Otherwise, or in addition, larger deviations either magnetic needles at designated points are used in the compass housing (eg Ludolph Compass) or movably mounted magnets in the compass housing by screws adjusted accordingly ( eg Airpath Compass) for compensation. This process is called offset. For this, the vehicle (ship ) is slowly rotated about the vertical axis leading through the compass (eg leading lights ) observed the optical bearing of a type known in their geographical orientation line and compared with the compass display. The values are recorded and kept as small as possible by means of the above devices. Residual errors are recorded in the deviation table. The compensation is repeated or made at full charge after shipyard steel stays ( welding). Remaining display errors (which should be below 5 ° ) are entered in a deviation table from which to each compass heading the corresponding correction can be read. In general aviation, the deviation must be reviewed according to specific changes in or on the aircraft or after certain time frames and the compass can be compensated. Corresponding requirements are found for example in the flight and operating manuals.
Dip
As the inclination angle between the tangent to the magnetic lines of force and the tangential plane to the ground surface ( horizontal) is called. In Central Europe, the inclination is about 66.5 °. In other words, the vertical component of the magnetic field is approximately twice as great as the horizontal component.
Since for determining the north direction, only the horizontal component of the magnetic field lines of importance in the construction of the inclination of the compass to be compensated individually. So in simple hiking compasses the southern half of the needle with a so-called Reiter for example, simply complaining. Such a compass can not be used in the southern hemisphere, otherwise the needle is crooked or at worst would touch the bottom of the compass housing. As a solution, two approaches to the market are:
- Many manufacturers have turned to for more favorable Compass models to divide the world into zones (two to five) and offer their own models for each zone. The variants differ in their emphasis on needle, so that they are balanced in the respective zone.
- In high-order models special needle suspensions and -mechanics are used, which make the compass used worldwide.
In the magnetic mariner's compass, the scale ( compass rose compass rose ) is attached with the graduation on the pointer which is either gimballed or in a liquid floats (spherical compass), so that it always lies horizontally despite the injury caused by the seas ship movements. The compass rose rotates as a whole, the direction is read from a rigidly connected to the housing mark. In contrast, in compasses are used on land, the compass rose attached to the case, and only the compass needle rotates. In relation to the earth's magnetic field rotates in both cases, the compass housing and the pointer ( compass needle / rose) remains aligned to the magnetic field lines.
The compass turning error
In aviation, the magnetic compass shows at accelerations incorrect values . This effect is ( at linear acceleration) or " rotational error " called " acceleration error " ( when flying ). When unaccelerated climb or descent this display error occurs, however, does not occur, contrary to the frequently expressed the opposite view.
It arises from the fact that the commonly used " brandy Compass" of the center of gravity is lower than the point at. For accelerations therefore tilts the compass, so that the vertical component of the magnetic field can pull the north pole of the compass magnet down what the ad falsified. A curve is therefore earlier on the northern courses, auszuleiten on southern later, when the compass to display ( This applies to the northern hemisphere, the southern hemisphere, the effect is opposite ).
There are acceleration and rotation flawless compasses, for example, models of the Swiss company Bohli magnets or the German company Schanz precision engineering, Schopfheim ( type SK 75 and SK 80). Bohli and Schanz- compass have been developed specifically for gliders and there in particular for use in the cloud flying. These compasses also have disadvantages; they must be adjusted by hand, the transverse position of the aircraft. Since the Cloud flying is generally prohibited in competition today, they are now rarely encountered in gliders. Outside the Segelflugszene these compasses are hardly known.
In powered flight curves are generally flown to the ( rotating error-free ) gyro so that the compass turning error here is hardly of practical importance.
Plural form
The plural of compass is according to Duden compasses. This form will also be lit immediately etymologically a: The original Italian word Compasso has the plural Compassi what, compasses is Germanized to compass.
Especially in circles of the Bundeswehr will often have to corruption Compasses as a plural form in the soldiers' language. This plural formation can be detected in any dictionary. They probably originated as an analogy to Atlas atlases; this analogy is incorrect because Atlas is a Greek proper name and thus has completely different Deklinationsformen.
Bracelet compasses as military equipment
The Adrianovkompass ' ( Компас Адрианова ) is a military compass, which was already widespread in the army of the empire. A first version was developed by the military surveyor Vladimir Adrianov 1907. Corresponding bracelet compasses were worn as well in the Red Army and the Soviet Army. In the iconographic image on the Reichstag in Berlin, May 2, 1945 fell in the flaggenhissenden soldiers that he seemed to be wearing two watches, one of which was airbrushed before publication. The widespread interpretation as looters is indeed close from a distance, is not necessarily due to the possible confusion with the wrist compass.
Pictures
Ball compass of a sailing yacht
Compass of the U.S. Army with two scales (Mil and degrees)
Aiming at an object with a compass
Aiming at the march target with iron sights and read the March number on the mirror
Matthew Seutter: Tabula Anemographica seu Pyxis Nautica, vulgo Compass, Augsburg 1734/1749
Compass with prism (scales)
Compass with prism (bearing 220 ° through the lens )
Compass with 400 Gon - division and conversion ruler ( D = degree = degree, G = Gon ' = line ) with linear measure in millimeters
Surveyor compass with inclinometer
Geologists compass after Prof. Clar with circular bubble and flap with inclinometer function also Stratumkompass
Map Compass with typical " global needle" ( Inklinationkompensiert )