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Geographical Mile
The geographical mile is an international unit of length determined by 1 minute of arc ( degree) along the Earth's equator. For the international ellipsoid 1924 this equalled 1855.4 metres. '' The American Practical Navigator'' 2017 defines the geographical mile as . Greater precision depends more on the choice of the Earth's radius of the used ellipsoid than on more careful measurement, since the radius of the geoid varies more than along the equator. In any ellipsoid, the length of a degree of longitude at the equator is exactly 60 geographical miles. The Earth's radius at the equator in the GRS80 ellipsoid is , which makes the geographical mile 1,855.3248 m. The rounding of the Earth's radius to metres in GRS80 has an effect of 0.0001 m. The shape of the Earth is a slightly flattened sphere, which results in the Earth's circumference being 0.168% larger when measured around the equator as compared to through the poles. The geographical mile is slightly larger than the naut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SI Units
The International System of Units, internationally known by the abbreviation SI (from French ), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science, technology, industry, and everyday commerce. The SI system is coordinated by the International Bureau of Weights and Measures, which is abbreviated BIPM from . The SI comprises a coherent system of units of measurement starting with seven base units, which are the second (symbol s, the unit of time), metre (m, length), kilogram (kg, mass), ampere (A, electric current), kelvin (K, thermodynamic temperature), mole (mol, amount of substance), and candela (cd, luminous intensity). The system can accommodate coherent units for an unlimited number of additional quantities. These are called coherent derived units, which can always be represented as products of powers of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautical Mile
A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees). Today the international nautical mile is defined as exactly . The derived unit of speed is the knot, one nautical mile per hour. Unit symbol There is no single internationally agreed symbol, with several symbols in use. * NM is used by the International Civil Aviation Organization. * nmi is used by the Institute of Electrical and Electronics Engineers and the United States Government Publishing Office. * M is used as the abbreviation for the nautical mile by the International Hydrographic Organization. * nm is a non-standard abbreviation used in many maritime applications and texts, including U.S. Government Coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Ordinance Of 1785
The Land Ordinance of 1785 was adopted by the United States Congress of the Confederation on May 20, 1785. It set up a standardized system whereby settlers could purchase title to farmland in the undeveloped west. Congress at the time did not have the power to raise revenue by direct taxation, so land sales provided an important revenue stream. The Ordinance set up a survey system that eventually covered over three-quarters of the area of the continental United States. The earlier Land Ordinance of 1784 was a resolution written by Thomas Jefferson calling for Congress to take action. The land west of the Appalachian Mountains, north of the Ohio River and east of the Mississippi River was to be divided into ten separate states. However, the 1784 resolution did not define the mechanism by which the land would become states, or how the territories would be governed or settled before they became states. The Ordinance of 1785 put the 1784 resolution in operation by providing a mecha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States asserts sovereignty over five Territories of the United States, major island territories and United States Minor Outlying Islands, various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's List of countries and dependencies by area, third-largest land area and List of countries and dependencies by population, third-largest population, exceeding 340 million. Its three Metropolitan statistical areas by population, largest metropolitan areas are New York metropolitan area, New York, Greater Los Angeles, Los Angel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swedish Units Of Measurement
Traditional Swedish units of measurement were standardized by law in 1665, prior to which they only existed as a number of related but differing local variants. The system was slightly revised in 1735. In 1855, a decimal reform was instituted that defined a new Swedish inch as Swedish foot (). Up to the middle of the 19th century, there was a law allowing the imposition of the death penalty for falsifying weights or measures. After a decision by the parliament in 1875, Sweden adopted the metric system on 22 November 1878, with a ten-year transition period until 1 January 1889. As part of the transition, the Swedish mil measurement was maintained, but was shortened from ''alnar'' – the equivalent of – to exactly . This measurement is still in use in both Sweden and Norway (which were in a union at the time). Old length units The Swedish units of length included the following: * ''aln'' – "forearm" (cf. ell) (pl. ''alnar''). After 1863, . Before that, from 1605, 59.38&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norwegian Units Of Measure
As in the case of the Danes, the Norwegians' earliest standards of measure can be derived from their ship burials. The 60-Norwegian-feet-long Kvalsund ship (18.8 m; 61.8 ft) was built ca. 700 AD and differs from the Danish boats less than it does from the Oseberg, Gokstad and Tune ships which all date from ca. 800 AD. Thwarts are typically spaced about 3 Norwegian feet (0.94 m; 3.1 ft) apart. In 1541, an ''alen'' in Denmark and Norway was defined by law to be the Sjælland ''alen''. Subsequently, the ''alen'' was defined by law as 2 Rhine feet from 1683. From 1824, the basic unit was defined as a ''fot'' being derived from astronomy as the length of a one-second pendulum times 12/38 at a latitude of 45°. The metric system was introduced in Norway in 1875, with Norway being one of the original signatories of the meter convention. Length * ''skruppel'' – scruple, 1/12 ''linje'' or approx. 0.18 mm. * ''linje'' – line, 1/12 ''tomme'' or ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NIST
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical science laboratory programs that include nanoscale science and technology, engineering, information technology, neutron research, material measurement, and physical measurement. From 1901 to 1988, the agency was named the National Bureau of Standards. History Background The Articles of Confederation, ratified by the colonies in 1781, provided: The United States in Congress assembled shall also have the sole and exclusive right and power of regulating the alloy and value of coin struck by their own authority, or by that of the respective states—fixing the standards of weights and measures throughout the United States. Article 1, section 8, of the Constitution of the United States, ratified in 1789, granted these powers to the new Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Institute Of Standards And Technology
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into Outline of physical science, physical science laboratory programs that include Nanotechnology, nanoscale science and technology, engineering, information technology, neutron research, material measurement, and physical measurement. From 1901 to 1988, the agency was named the National Bureau of Standards. History Background The Articles of Confederation, ratified by the colonies in 1781, provided: The United States in Congress assembled shall also have the sole and exclusive right and power of regulating the alloy and value of coin struck by their own authority, or by that of the respective states—fixing the standards of weights and measures throughout the United States. Article 1, section 8, of the Constitution of the United States, ratified i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Circle
In mathematics, a great circle or orthodrome is the circular intersection of a sphere and a plane passing through the sphere's center point. Discussion Any arc of a great circle is a geodesic of the sphere, so that great circles in spherical geometry are the natural analog of straight lines in Euclidean space. For any pair of distinct non- antipodal points on the sphere, there is a unique great circle passing through both. (Every great circle through any point also passes through its antipodal point, so there are infinitely many great circles through two antipodal points.) The shorter of the two great-circle arcs between two distinct points on the sphere is called the ''minor arc'', and is the shortest surface-path between them. Its arc length is the great-circle distance between the points (the intrinsic distance on a sphere), and is proportional to the measure of the central angle formed by the two points and the center of the sphere. A great circle is the largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ole Rømer
Ole Christensen Rømer (; 25 September 1644 – 19 September 1710) was a Danes, Danish astronomer who, in 1676, first demonstrated that light travels at a finite speed. Rømer also invented the modern thermometer showing the temperature between two fixed points, namely the points at which water respectively boils and freezes. Rømer made his discovery regarding the speed of light while working at the Paris Observatory, Royal Observatory in Paris and studying Jupiter's moon Io (moon), Io. He estimated that light takes about 11 minutes to travel from the Sun to Earth. Using today's knowledge of the Astronomical unit, Sun-Earth distance, this would amount to a speed of light of approximately 220,000 kilometers per second, compared to today's accepted value of just under 300,000 kilometers per second. In scientific literature, alternative spellings such as "Roemer", "Römer", or "Romer" are common. Biography Rømer was born on 25 September 1644 in Aarhus to merchant and skipper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Danish Units Of Measurement
The units of measurement in use in Denmark are currently part of the metric system. A variety of other historical weights and measures have been employed throughout the nation's history. History The Danes started with a system of units based on a Greek ''pous'' ("foot") of which they picked up through trade in the late Bronze Age/early Iron Age. Some early standards of measure can be recovered from measured drawings made of the Hjortspring boat, which though dating to the early Iron Age exemplifies plank-built vessels of the late Bronze Age and the Nydam ship. Thwarts are typically spaced about 3 ''fod'' apart. King Christian V of Denmark introduced an office to oversee weights and measures, a ''justervæsen''. This was first led by the royal mathematician Ole Rømer, who established a national system of weights and measures on May 1, 1683. Rømer's system, which he updated in 1698, was based on the Rhine foot. Its definitions included the following: * the Danish mile as 24, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Units Of Measurement
The units of measurement of German-speaking countries consist of a variety of units, with varying local standard definitions. While many were made redundant with the introduction of the metric system, some of these units are still used in everyday speech and even in stores and on street markets as shorthand for similar amounts in the metric system. For example, some customers ask for one pound (''ein Pfund'') of something when they want 500 grams. The metric system became compulsory on 1 January 1872, in Germany and on 1 January 1876, in Austria. Some obsolete German units have names similar to units that were traditionally used in other countries, and that are still used in a limited number of cases in the United Kingdom (imperial units) and in the United States (United States customary units). German system Before the introduction of the metric system in Germany, almost every town had its own definitions of the units shown below. Often towns posted local definitions o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
