1.
System of measurement
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A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce, systems of measurement in modern use include the metric system, the imperial system, and United States customary units. The French Revolution gave rise to the system, and this has spread around the world. In most systems, length, mass, and time are base quantities, later science developments showed that either electric charge or electric current could be added to extend the set of base quantities by which many other metrological units could be easily defined. Other quantities, such as power and speed, are derived from the set, for example. Such arrangements were satisfactory in their own contexts, the preference for a more universal and consistent system only gradually spread with the growth of science. Changing a measurement system has substantial financial and cultural costs which must be offset against the advantages to be obtained using a more rational system. However pressure built up, including scientists and engineers for conversion to a more rational. The unifying characteristic is that there was some definition based on some standard, eventually cubits and strides gave way to customary units to met the needs of merchants and scientists. In the metric system and other recent systems, a basic unit is used for each base quantity. Often secondary units are derived from the units by multiplying by powers of ten. Thus the basic unit of length is the metre, a distance of 1.234 m is 1,234 millimetres. Metrication is complete or nearly complete in almost all countries, US customary units are heavily used in the United States and to some degree in Liberia. Traditional Burmese units of measurement are used in Burma, U. S. units are used in limited contexts in Canada due to the large volume of trade, there is also considerable use of Imperial weights and measures, despite de jure Canadian conversion to metric. In the United States, metric units are used almost universally in science, widely in the military, and partially in industry, but customary units predominate in household use. At retail stores, the liter is a used unit for volume, especially on bottles of beverages. Some other standard non-SI units are still in use, such as nautical miles and knots in aviation. Metric systems of units have evolved since the adoption of the first well-defined system in France in 1795, during this evolution the use of these systems has spread throughout the world, first to non-English-speaking countries, and then to English speaking countries
2.
Imperial units
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The system of imperial units or the imperial system is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced. The Imperial units replaced the Winchester Standards, which were in effect from 1588 to 1825, the system came into official use across the British Empire. The imperial system developed from what were first known as English units, the Weights and Measures Act of 1824 was initially scheduled to go into effect on 1 May 1825. However, the Weights and Measures Act of 1825 pushed back the date to 1 January 1826, the 1824 Act allowed the continued use of pre-imperial units provided that they were customary, widely known, and clearly marked with imperial equivalents. Apothecaries units are mentioned neither in the act of 1824 nor 1825, at the time, apothecaries weights and measures were regulated in England, Wales, and Berwick-upon-Tweed by the London College of Physicians, and in Ireland by the Dublin College of Physicians. In Scotland, apothecaries units were unofficially regulated by the Edinburgh College of Physicians, the three colleges published, at infrequent intervals, pharmacopoeiae, the London and Dublin editions having the force of law. The Medical Act of 1858 transferred to The Crown the right to publish the official pharmacopoeia and to regulate apothecaries weights, Metric equivalents in this article usually assume the latest official definition. Before this date, the most precise measurement of the imperial Standard Yard was 0.914398416 metres, in 1824, the various different gallons in use in the British Empire were replaced by the imperial gallon, a unit close in volume to the ale gallon. It was originally defined as the volume of 10 pounds of distilled water weighed in air with brass weights with the standing at 30 inches of mercury at a temperature of 62 °F. The Weights and Measures Act of 1985 switched to a gallon of exactly 4.54609 l and these measurements were in use from 1826, when the new imperial gallon was defined, but were officially abolished in the United Kingdom on 1 January 1971. In the USA, though no longer recommended, the system is still used occasionally in medicine. The troy pound was made the unit of mass by the 1824 Act, however, its use was abolished in the UK on 1 January 1879, with only the troy ounce. The Weights and Measures Act 1855 made the pound the primary unit of mass. In all the systems, the unit is the pound. For the yard, the length of a pendulum beating seconds at the latitude of Greenwich at Mean Sea Level in vacuo was defined as 39.01393 inches, the imperial system is one of many systems of English units. Although most of the units are defined in more than one system, some units were used to a much greater extent, or for different purposes. The distinctions between these systems are not drawn precisely. One such distinction is that between these systems and older British/English units/systems or newer additions, the US customary system is historically derived from the English units that were in use at the time of settlement
3.
US customary units
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United States customary units are a system of measurements commonly used in the United States. The United States customary system developed from English units which were in use in the British Empire before the US declared its independence, however, the British system of measures was overhauled in 1824 to create the imperial system, changing the definitions of some units. Therefore, while many U. S. units are similar to their Imperial counterparts. The majority of U. S. customary units were redefined in terms of the meter and these definitions were refined by the international yard and pound agreement of 1959. Americans primarily use customary units in commercial activities, as well as for personal and social use, in science, medicine, many sectors of industry and some of government, metric units are used. The International System of Units, the form of the metric system, is preferred for many uses by the U. S. National Institute of Standards. The United States system of units is similar to the British imperial system, both systems are derived from English units, a system which had evolved over the millennia before American independence, and which had its roots in Roman and Anglo-Saxon units. The customary system was championed by the U. S. -based International Institute for Preserving and Perfecting Weights, advocates of the customary system saw the French Revolutionary, or metric, system as atheistic. An auxiliary of the Institute in Ohio published a poem with wording such as down with every metric scheme and A perfect inch, one adherent of the customary system called it a just weight and a just measure, which alone are acceptable to the Lord. The U. S. government passed the Metric Conversion Act of 1975, the legislation states that the federal government has a responsibility to assist industry as it voluntarily converts to the metric system, i. e. metrification. This is most evident in U. S. labeling requirements on food products, according to the CIA Factbook, the United States is one of three nations that have not adopted the metric system as their official system of weights and measures. U. S. customary units are used on consumer products. Metric units are standard in science, medicine, as well as many sectors of industry and government, the metric system also lacks a parallel to the foot. Frequently, however, these units designate quite different sizes, for example, the mile ranged by country from one-half to five U. S. miles, foot and pound also had varying definitions. Historically, a range of non-SI units were used in the U. S. and in Britain. This article deals only with the commonly used or officially defined in the U. S. For measuring length, the U. S. customary system uses the inch, foot, yard, and mile, since July 1,1959, these have been defined on the basis of 1 yard =0.9144 meters except for some applications in surveying. The U. S. the United Kingdom and other Commonwealth countries agreed on this definition, the NAD27 was replaced in the 1980s by the North American Datum of 1983, which is defined in meters
4.
Length
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In geometric measurements, length is the most extended dimension of an object. In the International System of Quantities, length is any quantity with dimension distance, in other contexts length is the measured dimension of an object. For example, it is possible to cut a length of a wire which is shorter than wire thickness. Length may be distinguished from height, which is vertical extent, and width or breadth, length is a measure of one dimension, whereas area is a measure of two dimensions and volume is a measure of three dimensions. In most systems of measurement, the unit of length is a base unit, measurement has been important ever since humans settled from nomadic lifestyles and started using building materials, occupying land and trading with neighbours. As society has become more technologically oriented, much higher accuracies of measurement are required in a diverse set of fields. One of the oldest units of measurement used in the ancient world was the cubit which was the length of the arm from the tip of the finger to the elbow. This could then be subdivided into shorter units like the foot, hand or finger, the cubit could vary considerably due to the different sizes of people. After Albert Einsteins special relativity, length can no longer be thought of being constant in all reference frames. Thus a ruler that is one meter long in one frame of reference will not be one meter long in a frame that is travelling at a velocity relative to the first frame. This means length of an object is variable depending on the observer, in the physical sciences and engineering, when one speaks of units of length, the word length is synonymous with distance. There are several units that are used to measure length, in the International System of Units, the basic unit of length is the metre and is now defined in terms of the speed of light. The centimetre and the kilometre, derived from the metre, are commonly used units. In U. S. customary units, English or Imperial system of units, commonly used units of length are the inch, the foot, the yard, and the mile. Units used to denote distances in the vastness of space, as in astronomy, are longer than those typically used on Earth and include the astronomical unit, the light-year. Dimension Distance Orders of magnitude Reciprocal length Smoot Unit of length
5.
Yard
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The yard is an English unit of length, in both the British imperial and US customary systems of measurement, that comprises 3 feet or 36 inches. It is by international agreement in 1959 standardized as exactly 0.9144 meters, a metal yardstick originally formed the physical standard from which all other units of length were officially derived in both English systems. In the 19th and 20th centuries, increasingly powerful microscopes and scientific measurement detected variation in these prototype yards which became significant as technology improved. In 1959, the United States, United Kingdom, Australia, New Zealand, the name derives from the Old English gerd, gyrd, &c. which was used for branches, staves, and measuring rods. It is first attested in the late-7th century laws of Ine of Wessex, where the yard of land mentioned is the yardland, an old English unit of tax assessment equal to 1⁄4 hide. Around the same time, the Lindisfarne Gospels account of the messengers from John the Baptist in the Book of Matthew used it for a branch swayed by the wind. In addition to the yardland, Old and Middle English both used their forms of yard to denote the lengths of 15 or 16 1⁄2 ft used in computing acres. A unit of three English feet is attested in a statute of c. 1300 but there it is called an ell, the use of the word yard to describe this length is first attested in Langlands poem on Piers Plowman. The usage seems to derive from the prototype standard rods held by the king, the word yard is a homonym of yard in the sense of an enclosed area of land. This second meaning of yard has a related to the verb to gird and is probably not related. The origin of the measure is uncertain, both the Romans and the Welsh used multiples of a shorter foot, but 2 1⁄2 Roman feet was a step and 3 Welsh feet was a pace. The Proto-Germanic cubit or arms-length has been reconstructed as *alinâ, which developed into the Old English ęln, Middle English elne and this has led some to derive the yard of three English feet from pacing, others from the ell or cubit, others from Henry Is arm standard. Based on the etymology of the yard, others suggest it originally derived from the girth of a persons waist. But the yard was the standard adopted by the early English soverigns. The yard continued till the reign of Henry VII. when the ell was introduced, that being a yard, the ell was borrowed from the Paris drapers. Subsequently, however, Queen Elizabeth re-introduced the yard as the English standard of measure, the earliest record of a prototype measure is the statute II Edgar Cap. 8, which survives in several variant manuscripts, in it, Edgar the Peaceful directed the Witenagemot at Andover that the measure held at Winchester should be observed throughout his realm. The statutes of William I similarly refer to and uphold the measures of his predecessors without naming them
6.
Inch
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The inch is a unit of length in the imperial and United States customary systems of measurement now formally equal to 1⁄36 yard but usually understood as 1⁄12 of a foot. Derived from the Roman uncia, inch is also used to translate related units in other measurement systems. The English word inch was a borrowing from Latin uncia not present in other Germanic languages. The vowel change from Latin /u/ to English /ɪ/ is known as umlaut, the consonant change from the Latin /k/ to English /tʃ/ or /ʃ/ is palatalisation. Both were features of Old English phonology, inch is cognate with ounce, whose separate pronunciation and spelling reflect its reborrowing in Middle English from Anglo-Norman unce and ounce. In many other European languages, the word for inch is the same as or derived from the word for thumb, the inch is a commonly used customary unit of length in the United States, Canada, and the United Kingdom. It is also used in Japan for electronic parts, especially display screens, for example, three feet two inches can be written as 3′ 2″. Paragraph LXVII sets out the fine for wounds of various depths, one inch, one shilling, an Anglo-Saxon unit of length was the barleycorn. After 1066,1 inch was equal to 3 barleycorns, which continued to be its legal definition for several centuries, similar definitions are recorded in both English and Welsh medieval law tracts. One, dating from the first half of the 10th century, is contained in the Laws of Hywel Dda which superseded those of Dyfnwal, both definitions, as recorded in Ancient Laws and Institutes of Wales, are that three lengths of a barleycorn is the inch. However, the oldest surviving manuscripts date from the early 14th century, john Bouvier similarly recorded in his 1843 law dictionary that the barleycorn was the fundamental measure. He noted that this process would not perfectly recover the standard, before the adoption of the international yard and pound, various definitions were in use. In the United Kingdom and most countries of the British Commonwealth, the United States adopted the conversion factor 1 metre =39.37 inches by an act in 1866. In 1930, the British Standards Institution adopted an inch of exactly 25.4 mm, the American Standards Association followed suit in 1933. By 1935, industry in 16 countries had adopted the industrial inch as it came to be known, in 1946, the Commonwealth Science Congress recommended a yard of exactly 0.9144 metres for adoption throughout the British Commonwealth. This was adopted by Canada in 1951, the United States on 1 July 1959, Australia in 1961, effective 1 January 1964, and the United Kingdom in 1963, effective on 1 January 1964. The new standards gave an inch of exactly 25.4 mm,1.7 millionths of a longer than the old imperial inch and 2 millionths of an inch shorter than the old US inch. The United States retains the 1/39. 37-metre definition for survey purposes and this is approximately 1/8-inch in a mile
7.
Metric system
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The metric system is an internationally agreed decimal system of measurement. Many sources also cite Liberia and Myanmar as the other countries not to have done so. Although the originators intended to devise a system that was accessible to all. Control of the units of measure was maintained by the French government until 1875, when it was passed to an intergovernmental organisation. From its beginning, the features of the metric system were the standard set of interrelated base units. These base units are used to larger and smaller units that could replace a huge number of other units of measure in existence. Although the system was first developed for use, the development of coherent units of measure made it particularly suitable for science. Although the metric system has changed and developed since its inception, designed for transnational use, it consisted of a basic set of units of measurement, now known as base units. At the outbreak of the French Revolution in 1789, most countries, the metric system was designed to be universal—in the words of the French philosopher Marquis de Condorcet it was to be for all people for all time. However, these overtures failed and the custody of the metric system remained in the hands of the French government until 1875. In languages where the distinction is made, unit names are common nouns, the concept of using consistent classical names for the prefixes was first proposed in a report by the Commission on Weights and Measures in May 1793. The prefix kilo, for example, is used to multiply the unit by 1000, thus the kilogram and kilometre are a thousand grams and metres respectively, and a milligram and millimetre are one thousandth of a gram and metre respectively. These relations can be written symbolically as,1 mg =0, however,1935 extensions to the prefix system did not follow this convention, the prefixes nano- and micro-, for example have Greek roots. During the 19th century the prefix myria-, derived from the Greek word μύριοι, was used as a multiplier for 10000, prefixes are not usually used to indicate multiples of a second greater than 1, the non-SI units of minute, hour and day are used instead. On the other hand, prefixes are used for multiples of the unit of volume. The base units used in the system must be realisable. Each of the units in SI is accompanied by a mise en pratique published by the BIPM that describes in detail at least one way in which the base unit can be measured. In practice, such realisation is done under the auspices of a mutual acceptance arrangement, in the original version of the metric system the base units could be derived from a specified length and the weight of a specified volume of pure water
8.
International System of Units
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The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, the system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system was published in 1960 as the result of an initiative began in 1948. It is based on the system of units rather than any variant of the centimetre-gram-second system. The motivation for the development of the SI was the diversity of units that had sprung up within the CGS systems, the International System of Units has been adopted by most developed countries, however, the adoption has not been universal in all English-speaking countries. The metric system was first implemented during the French Revolution with just the metre and kilogram as standards of length, in the 1830s Carl Friedrich Gauss laid the foundations for a coherent system based on length, mass, and time. In the 1860s a group working under the auspices of the British Association for the Advancement of Science formulated the requirement for a coherent system of units with base units and derived units. Meanwhile, in 1875, the Treaty of the Metre passed responsibility for verification of the kilogram, in 1921, the Treaty was extended to include all physical quantities including electrical units originally defined in 1893. The units associated with these quantities were the metre, kilogram, second, ampere, kelvin, in 1971, a seventh base quantity, amount of substance represented by the mole, was added to the definition of SI. On 11 July 1792, the proposed the names metre, are, litre and grave for the units of length, area, capacity. The committee also proposed that multiples and submultiples of these units were to be denoted by decimal-based prefixes such as centi for a hundredth, on 10 December 1799, the law by which the metric system was to be definitively adopted in France was passed. Prior to this, the strength of the magnetic field had only been described in relative terms. The technique used by Gauss was to equate the torque induced on a magnet of known mass by the earth’s magnetic field with the torque induced on an equivalent system under gravity. The resultant calculations enabled him to assign dimensions based on mass, length, a French-inspired initiative for international cooperation in metrology led to the signing in 1875 of the Metre Convention. Initially the convention only covered standards for the metre and the kilogram, one of each was selected at random to become the International prototype metre and International prototype kilogram that replaced the mètre des Archives and kilogramme des Archives respectively. Each member state was entitled to one of each of the prototypes to serve as the national prototype for that country. Initially its prime purpose was a periodic recalibration of national prototype metres. The official language of the Metre Convention is French and the version of all official documents published by or on behalf of the CGPM is the French-language version
9.
Metre
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The metre or meter, is the base unit of length in the International System of Units. The metre is defined as the length of the path travelled by light in a vacuum in 1/299792458 seconds, the metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole. In 1799, it was redefined in terms of a metre bar. In 1960, the metre was redefined in terms of a number of wavelengths of a certain emission line of krypton-86. In 1983, the current definition was adopted, the imperial inch is defined as 0.0254 metres. One metre is about 3 3⁄8 inches longer than a yard, Metre is the standard spelling of the metric unit for length in nearly all English-speaking nations except the United States and the Philippines, which use meter. Measuring devices are spelled -meter in all variants of English, the suffix -meter has the same Greek origin as the unit of length. This range of uses is found in Latin, French, English. Thus calls for measurement and moderation. In 1668 the English cleric and philosopher John Wilkins proposed in an essay a decimal-based unit of length, as a result of the French Revolution, the French Academy of Sciences charged a commission with determining a single scale for all measures. In 1668, Wilkins proposed using Christopher Wrens suggestion of defining the metre using a pendulum with a length which produced a half-period of one second, christiaan Huygens had observed that length to be 38 Rijnland inches or 39.26 English inches. This is the equivalent of what is now known to be 997 mm, no official action was taken regarding this suggestion. In the 18th century, there were two approaches to the definition of the unit of length. One favoured Wilkins approach, to define the metre in terms of the length of a pendulum which produced a half-period of one second. The other approach was to define the metre as one ten-millionth of the length of a quadrant along the Earths meridian, that is, the distance from the Equator to the North Pole. This means that the quadrant would have defined as exactly 10000000 metres at that time. To establish a universally accepted foundation for the definition of the metre, more measurements of this meridian were needed. This portion of the meridian, assumed to be the length as the Paris meridian, was to serve as the basis for the length of the half meridian connecting the North Pole with the Equator
10.
Prime (symbol)
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The prime symbol, double prime symbol, triple prime symbol, quadruple prime symbol etc. are used to designate units and for other purposes in mathematics, the sciences, linguistics and music. The prime symbol is similar to the Hebrew geresh, but in modern fonts the geresh is designed to be aligned with the Hebrew letters. The prime symbol is used to represent feet, arcminutes. However, for convenience, a is commonly used, the double prime represents inches, arcseconds, and seconds. However, for convenience, a is commonly used, thus, 3′ 5″ could mean 3 feet and 5 inches or 3 minutes and 5 seconds. As an angular measurement, 3° 5′ 30″ means 3 degrees,5 arcminutes and 30 arcseconds, the triple prime in watchmaking represents a ligne. It is also found in historical astronomical works to denote thirds. Likewise, a quadruple prime denotes fourths, in mathematics, the prime is generally used to generate more variable names for things which are similar, without resorting to subscripts – x′ generally means something related to or derived from x. For example, if a point is represented by the Cartesian coordinates, the prime symbol is not related to prime numbers. Likewise are f ‴ and f ⁗, similarly, if y = f then y′ and y″ are the first and second derivatives of y with respect to x. Set complement, A′ is the complement of the set A, the negation of an event in probability theory, Pr =1 − Pr. The result of a transformation, Tx = x′ The transpose of a matrix, the prime is said to decorate the letter to which it applies. The same convention is adopted in functional programming, particularly in Haskell, in physics, the prime is used to denote variables after an event. For example, vA′ would indicate the velocity of object A after an event and it is also commonly used in relativity, The event at in frame S has coordinates in frame S′. In chemistry, it is used to distinguish between different functional groups connected to an atom in a molecule, such as R and R′, representing different alkyl groups in an organic compound. The carbonyl carbon in proteins is denoted as C′, which distinguishes it from the backbone carbon, the alpha carbon. In molecular biology, the prime is used to denote the positions of carbon on a ring of deoxyribose or ribose, the prime distinguishes places on these two chemicals, rather than places on other parts of DNA or RNA, like phosphate groups or nucleic acids. The chemistry of this demands that the 3 prime OH is extended by DNA synthesis
11.
Units of measurement
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A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same quantity. Any other value of quantity can be expressed as a simple multiple of the unit of measurement. For example, length is a physical quantity, the metre is a unit of length that represents a definite predetermined length. When we say 10 metres, we actually mean 10 times the definite predetermined length called metre, the definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day. Different systems of units used to be very common, now there is a global standard, the International System of Units, the modern form of the metric system. In trade, weights and measures is often a subject of regulation, to ensure fairness. The International Bureau of Weights and Measures is tasked with ensuring worldwide uniformity of measurements, metrology is the science for developing nationally and internationally accepted units of weights and measures. In physics and metrology, units are standards for measurement of quantities that need clear definitions to be useful. Reproducibility of experimental results is central to the scientific method, a standard system of units facilitates this. Scientific systems of units are a refinement of the concept of weights, science, medicine, and engineering often use larger and smaller units of measurement than those used in everyday life and indicate them more precisely. The judicious selection of the units of measurement can aid researchers in problem solving, in the social sciences, there are no standard units of measurement and the theory and practice of measurement is studied in psychometrics and the theory of conjoint measurement. A unit of measurement is a quantity of a physical property. Units of measurement were among the earliest tools invented by humans, primitive societies needed rudimentary measures for many tasks, constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials. Weights and measures are mentioned in the Bible and it is a commandment to be honest and have fair measures. As of the 21st Century, multiple unit systems are used all over the world such as the United States Customary System, the British Customary System, however, the United States is the only industrialized country that has not yet completely converted to the Metric System. The systematic effort to develop an acceptable system of units dates back to 1790 when the French National Assembly charged the French Academy of Sciences to come up such a unit system. After this treaty was signed, a General Conference of Weights, the CGPM produced the current SI system which was adopted in 1954 at the 10th conference of weights and measures. Currently, the United States is a society which uses both the SI system and the US Customary system
12.
United States customary units
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United States customary units are a system of measurements commonly used in the United States. The United States customary system developed from English units which were in use in the British Empire before the US declared its independence, however, the British system of measures was overhauled in 1824 to create the imperial system, changing the definitions of some units. Therefore, while many U. S. units are similar to their Imperial counterparts. The majority of U. S. customary units were redefined in terms of the meter and these definitions were refined by the international yard and pound agreement of 1959. Americans primarily use customary units in commercial activities, as well as for personal and social use, in science, medicine, many sectors of industry and some of government, metric units are used. The International System of Units, the form of the metric system, is preferred for many uses by the U. S. National Institute of Standards. The United States system of units is similar to the British imperial system, both systems are derived from English units, a system which had evolved over the millennia before American independence, and which had its roots in Roman and Anglo-Saxon units. The customary system was championed by the U. S. -based International Institute for Preserving and Perfecting Weights, advocates of the customary system saw the French Revolutionary, or metric, system as atheistic. An auxiliary of the Institute in Ohio published a poem with wording such as down with every metric scheme and A perfect inch, one adherent of the customary system called it a just weight and a just measure, which alone are acceptable to the Lord. The U. S. government passed the Metric Conversion Act of 1975, the legislation states that the federal government has a responsibility to assist industry as it voluntarily converts to the metric system, i. e. metrification. This is most evident in U. S. labeling requirements on food products, according to the CIA Factbook, the United States is one of three nations that have not adopted the metric system as their official system of weights and measures. U. S. customary units are used on consumer products. Metric units are standard in science, medicine, as well as many sectors of industry and government, the metric system also lacks a parallel to the foot. Frequently, however, these units designate quite different sizes, for example, the mile ranged by country from one-half to five U. S. miles, foot and pound also had varying definitions. Historically, a range of non-SI units were used in the U. S. and in Britain. This article deals only with the commonly used or officially defined in the U. S. For measuring length, the U. S. customary system uses the inch, foot, yard, and mile, since July 1,1959, these have been defined on the basis of 1 yard =0.9144 meters except for some applications in surveying. The U. S. the United Kingdom and other Commonwealth countries agreed on this definition, the NAD27 was replaced in the 1980s by the North American Datum of 1983, which is defined in meters
13.
Metrology
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The field of metrology is important for establishing a common understanding of units, which is crucial in linking human activities. This led to the creation of the decimal based metric system in 1795 to establish a set of standards for types of measurements. This has since evolved into the International System of Units as a result of a made in the 11th Conference Generale des Poids et Mesures in 1960. The NMS greatly effects how measurements are undertaken in the country and this has wide reaching impacts in a variety of different regions of society. It has implications in the area of economies, energy, environment, health, manufacturing, industry, consumer confidence, the effects of metrology on trade and the economy are some of the easiest observed societal impacts. The field of metrology is important for establishing a common understanding of units and these base concepts of metrology are propagated by the three main fields of metrology, which are, scientific or fundamental metrology, applied, technical or industrial metrology, and legal metrology. While there is no definition of fundamental metrology it is considered to be the top level of scientific metrology that strives for the highest level of accuracy. The BIPM maintains a database of the calibration and measurement capabilities of various institutes around the world. These institutes, whose activities are peer-reviewed, provide the reference points for metrological traceability. In the area of measurement, the BIPM has identified nine metrology areas, including length, mass, although the emphasis in this area of metrology is on the measurements themselves, traceability of the calibration of the measurement devices is necessary to ensure confidence in the measurements. Industrial metrology is important to the economical and industrial development of a country, such statutory requirements might arise from, amongst others, the needs for protection of health, public safety, the environment, enabling taxation, protection of consumers and fair trade. The International Organization for Legal Metrology was established to assist in harmonising such regulations across national boundaries to ensure that legal requirements do not inhibit trade. In Europe WELMEC was established in 1990 to promote cooperation on the field of metrology in the European Union. Throughout history the ability to make measurements has been instrumental in the progress of mankind, the ability to measure alone is not sufficient, rather the ability to compare separate measurements and have agreeability is crucial for the measurements to be meaningful. The first record of a permanent standard is from 2900 BC, the cubit was decreed to be the length of the Pharaohs forearm plus the width of his hand and replica standards were given out to builders. The success of standardized length during the building of the pyramids is evidenced by the lengths of the pyramid bases differing by no more than 0. 05%, other civilizations produced their own measurement standards that were accepted throughout their nations. The architecture of the Roman and Greek empires were based on their own systems of measurement. Nonetheless, the fall of great empires and the rise of the Dark Ages caused much of measurement knowledge
14.
Ancient Greek units of measurement
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Ancient Greek units of measurement varied according to location and epoch. Systems of ancient weights and measures evolved as needs changed, Solon, some units of measurement were found to be convenient for trade within the Mediterranean region and these units became increasingly common to different city states. The calibration and use of measuring devices became more sophisticated, by about 500 BC, Athens had a central depository of official weights and measures, the Tholos, where merchants were required to test their measuring devices against official standards. Some Greek measures of length were named after parts of the body, such as the δάκτυλος or finger, a common unit in both measures throughout historic Greece was the cotyle or cotyla whose absolute value varied from one place to another between 210 ml and 330 ml. The basic unit for both solid and liquid measures was the κύαθος, thus for example the English pound has been both a unit of weight and a unit of currency. Greek weights similarly bear a resemblance to Greek currency yet the origin of the Greek standards of weights is often disputed. The Attic/Euboean standard was based on the barley corn, of which there were supposedly twelve to one obol. However, weights that have been retrieved by historians and archeologists show considerable variations from theoretical standards, a table of standards derived from theory is as follows, Athenians measured the day by sundials and unit fractions. Periods during night or day were measured by a clock that dripped at a steady rate. Whereas the day in the Gregorian calendar commences after midnight, the Greek day began after sunset, Athenians named each year after the Archon Eponymos for that year, and in Hellenistic times years were reckoned in quadrennial epochs according to the Olympiad. In archaic and early classical Greece, months followed the cycle of the Moon which made them not fit exactly into the length of the solar year, thus, if not corrected, the same month would migrate slowly into different seasons of the year. The Athenian year was divided into 12 months, with one month being inserted between the sixth and seventh months every second year. Even with this intercalary month, the Athenian or Attic calendar was still fairly inaccurate, Greek and Roman Weights, Measures and Currency. Archived from the original on 6 August 2007, online Conversion of Ancient Greek Units
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Ancient Roman units of measurement
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The ancient Roman units of measurement were largely built on the Hellenic system, which in turn was built upon Egyptian and Mesopotamian influences. The Roman units were comparatively consistent and well documented, the basic unit of Roman linear measurement was the pes or Roman foot. Investigation of its relation to the English foot goes back at least to 1647, an accepted modern value is 296 mm. The Roman foot was sub-divided either like the Greek pous into 16 digiti or fingers, frontinus writes in the 1st century AD that the digitus was used in Campania and most parts of Italy. Columella also gives uncial divisions of the jugerum, tabulated by the translator of the 1745 Millar edition as follows, Both liquid. As no two surviving examples are identical, scholarly opinion ranges from 530 ml to 580 ml. Cardarelli gives a value 549.28 ml. A1952 estimate for its value in Pliny the Elders Natural History estimated it as 500 ml.3 ml, which falls comfortably within the accepted range. The core volume units are, amphora quadrantal – one cubic pes congius – a half-pes cube sextarius – literally 1⁄6, of a congius The units of weight or mass were mostly based on factors of 12. Several of the names were also the names of coins during the Roman Republic and had the same fractional value of a larger base unit, libra for weight. Modern estimates of the range from 322 to 329 g with 5076 grains or 328.9 g an accepted figure. The as was reduced from 12 ounces to 2 after the First Punic War, to 1 during the Second Punic War, the divisions of the libra were, The subdivisions of the uncia were, The complicated Roman calendar was replaced by the Julian calendar in 45 BC. In the Julian calendar, a year is 365 days long. Between 45 BC and AD1, leap years occurred at irregular intervals, starting in AD4, leap years occurred regularly every four years. Year numbers were used, rather, the year was specified by naming the Roman consuls for that year. When a year number was required, the Greek Olympiads were used, or the count of years since the founding of Rome, in the middle ages, the year numbering was changed to the Anno Domini count. The Romans grouped days into a cycle called a nundina. Each astrological day was reckoned to begin at sunrise, the Jews also used a seven-day week, which began Saturday evening. The seventh day of the week they called Sabbath, the days they numbered rather than named, except for Friday
16.
Chinese units of measurement
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Chinese units of measurement are the customary and traditional units of measure used in China. In the Peoples Republic of China, the units were re-standardised during the late 20th century to make them approximate SI units, many of the units were formerly based on the number 16 instead of 10. The Chinese name for most SI units is based on that of the closest traditional unit, when it is necessary to emphasize which system is used, the words market for traditional units or common/standard for SI units may be added in front of the name. SI is the system of units, but traditional units are still ubiquitously used in everyday life. Note, The names lí and fēn for small units are the same for length, area, according to the Liji, the legendary Yellow Emperor created the first measurement units. The Xiao Erya and the Kongzi Jiayu state that length units were derived from the human body, according to the Records of the Grand Historian, these human body units caused inconsistency, and Yu the Great, another legendary figure, unified the length measurements. Rulers with decimal units have been unearthed from Shang Dynasty tombs, in the Zhou Dynasty, the king conferred nobles with powers of the state and the measurement units began to be inconsistent from state to state. After the Warring States period, Qin Shi Huang unified China, in the Han Dynasty, these measurements were still being used, and were documented systematically in the Book of Han. Astronomical instruments show little change of the length of chi in the following centuries and it was not until the introduction of decimal units in the Ming Dynasty that the traditional system was revised. On 7 January 1915, the Beiyang Government promulgated a measurement law to use not only metric system as the standard, in 1976 the Hong Kong Metrication Ordinance allowed a gradual replacement of the system in favor of the International System of Units metric system. The Weights and Measures Ordinance defines the metric, Imperial, as of 2012, all three systems are legal for trade and are in widespread use. On 24 August 1992, Macau published Law No, traditional units of length include the chi, bu, and li. The precise length of these units, and the ratios between these units, has varied over time,1 bu has consisted of either 5 or 6 chi, while 1 li has consisted of 300 or 360 bu. All metric values given in the tables are exact unless otherwise specified by the approximation sign ~, certain units are also listed at List of Chinese classifiers → Measurement units. The Chinese word for metre is 米 mǐ, this can take the Chinese standard SI prefixes, a kilometre, however, may also be called 公里 gōnglǐ, i. e. a metric lǐ. For example, a kilometre is 平方公里 píngfāng gōnglǐ. These units are used to measure cereal grains, among other things, in imperial times, the physical standard for these was the jialiang. In the case of volume, the market and metric shēng coincide, the Chinese standard SI prefixes may be added to this word shēng
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English units
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English units are the historical units of measurement used in England up to 1826, which evolved as a combination of the Anglo-Saxon and Roman systems of units. Various standards have applied to English units at different times, in different places, the units were replaced by Imperial Units in 1824 by a Weights and Measures Act, which retained many but not all of the unit names and redefined many of the definitions. Very little is known of the measurement units of the British Isles prior to Roman colonization in the 1st century CE, during the Roman period, Roman Britain relied on Ancient Roman units of measurement. During the Anglo-Saxon period, the North German foot of 335 millimetres was the basis for other units of linear measurement. The foot was divided into 4 palms or 12 thumbs, a cubit was 2 feet, an elne 4 feet. The rod was 15 Anglo-Saxon feet, the furlong 10 rods, an acre was 4 ×40 rods, i. e.160 square rods or 36,000 square Anglo-Saxon feet. From the time of Offa King of Mercia until 1526 the Saxon pound, the Compositio retained the Anglo-Saxon rod of 5.03 metres and the acre of 4 ×40 rods. However, it redefined the yard, foot, inch, thus, the rod went from 5 old yards to 5 1⁄2 new yards, or 15 old feet to 16 1⁄2 new feet. The furlong went from 600 old feet to 660 new feet, the acre went from 36,000 old square feet to 43,560 new square feet. Scholars have speculated that the Compositio may have represented a compromise between two systems of the units, the Anglo-Saxon and the Roman. Contrary to popular belief, the Norman conquest of England had little effect on British weights and measures other than to one new unit. William the Conqueror, in one of his first legislative acts, confirmed existing Anglo-Saxon measurement, another popular myth is that the Magna Carta of 1215 had any significant effect on English weights and measures, as this document only mentions one unit but does not define it. Later development of the English system continued by defining the units by law, Standards were renewed in 1496,1588 and 1758. The English system then spread to parts of the British Empire. 17065 &6 Anne c27 Wine gallon to be a vessel with an even bottom 7 diameter throughout and 6 deep from top to bottom of the inside, or holding 231 in³. 17066 Anne c11 Act of Union decreed, the weights,171312 Anne c17 The legal coal bushel to be round with a plain and even bottom,19 1/2 from outside to outside and to hold 1 Winchester bushel and 1 quart of water. 17185 Geo I c18 Decreed Scots Pint exactly 103 in³,18256 Geo IV c12 Delayed introduction of Imperial weights and measures from 1 May 1825 to 1 January 1826. 185316 &17 Vict c29 Permitted the use of decimal Bullion weights,186629 &30 Vict c82 Standards of Weights, Measures and Coinage Act, transferred all duties and standards from the Exchequer to the newly created Standards Department of the Board of Trade
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Digit (unit)
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The digit or finger is an ancient and obsolete non-SI unit of measurement of length. It was originally based on the breadth of a human finger and it was a fundamental unit of length in the Ancient Egyptian, Mesopotamian, Hebrew, Ancient Greek and Roman systems of measurement. In astronomy a digit is one twelfth of the diameter of the sun or the moon, the digit, also called a finger or fingerbreadth, is a unit of measurement originally based on the breadth of a human finger. In Ancient Egypt it was the unit of subdivision of the cubit. On surviving Ancient Egyptian cubit-rods, the royal cubit is divided into seven palms of four digits or fingers each, the royal cubit measured approximately 525 mm, so the length of the ancient Egyptian digit was about 19 mm. In the classical Akkadian Empire system instituted in about 2150 BC during the reign of Naram-Sin, the cubit was equivalent to approximately 497 mm, so the finger was equal to about 17 mm. Basic length was used in architecture and field division, a digit, when used as a unit of length, is usually a sixteenth of a foot or 3/4. The width of a human male finger tip is indeed about 2 centimetres. In English this unit has mostly fallen out of use, as do others based on the arm, finger, palm, hand, shaftment, span, cubit. It is in equal to the foot-nail, although the term nail can also be used as 1/16 of yard. In astronomy a digit is, or was until recently, one twelfth of the diameter of the sun or the moon and this is found in the Moralia of Plutarch, XII,23, but the definition as exactly one twelfth of the diameter may be due to Ptolemy. Sosigenes of Alexandria had observed in the 1st century AD that on a dioptra, the unit was used in Arab or Islamic astronomical works such as those of Ṣadr al‐Sharīʿa al‐Thānī, where it is called Arabic, إصبعا iṣba, digit or finger. The astronomical digit was in use in Britain for centuries, the unit is apparently not in current use, but is found in recent dictionaries. A finger of a beverage is colloquially referred to as a digit
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Metrication
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Metrication or metrification is conversion to the metric system of units of measurement. Since 2006, three countries formally do not use the system as their main standard of measurement, the United States, Myanmar. In the United Kingdom metric is the system for most regulated trading by weight or measure purposes. For example, miles, yards, and feet remain the official units for road signage –, the Imperial pint also remains a permitted unit for milk in returnable bottles and for draught beer and cider in British pubs. Television screen and clothing sizes tend to be denominated in inches only, some sources now identify Liberia as metric, and the government of Myanmar has stated that the country would metricate with a goal of completion by 2019. Both Myanmar and Liberia are substantially metric countries, trading internationally in metric units, visiting advocates of metrication have stated that they use metric units for many things internally with exceptions such as old petrol pumps in Myanmar, calibrated in British Imperial gallons. These and other countries have adopted measures to some degree through international trade and standardization for example. The United States mandated the acceptance of the system in 1866 for commercial and legal proceedings. The United Kingdom followed suit in 1897 and did not make the use of metric units compulsory for most purposes until 1995, in 1971 the National Bureau of Standards completed a three-year study of the impact of increasing worldwide metric use on the U. S. The study concluded with a report to Congress entitled A Metric America – A Decision Whose Time Has Come, since then metric use has increased in the U. S. principally in the manufacturing and educational sectors. On 23 December 1975, President Gerald Ford signed Public Law 94-168 and this act declares a national policy of coordinating the increasing use of the metric system in the U. S. Metric Board whose functions as of 1 October 1982 were transferred to the Dept of Commerce, Office of Metric Programs, most countries have adopted the metric system officially over a transitional period where both units are used for a set period of time. Some countries such as Guyana, for example, have adopted the metric system. Antigua and Barbuda, also officially metric, is moving toward total implementation of the metric system, the government had announced that they have plans to convert their country to the metric system by the first quarter of 2015. Other Caribbean countries such as Saint Lucia are officially metric but are still in the process toward full conversion, the European Union used the Units of Measure Directive to attempt to achieve a common system of weights and measures and to facilitate the European Single Market. Throughout the 1990s, the European Commission helped accelerate the process for member countries to complete their metric conversion processes, the United Kingdom secured permanent exemptions for the mile and yard in road markings, and for the pint of draught beer sold in pubs. In 2007, the European Commission also announced that it was to abandon the requirement for metric-only labelling on packaged goods, other countries using the imperial system completed official metrication during the second half of the 20th century or the first decade of the 21st century. The most recent to complete this process was the Republic of Ireland, in January 2007 NASA decided to use metric units for all future moon missions, in line with the practice of other space agencies
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Altitude
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Altitude or height is defined based on the context in which it is used. As a general definition, altitude is a measurement, usually in the vertical or up direction. The reference datum also often varies according to the context, although the term altitude is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage. Vertical distance measurements in the direction are commonly referred to as depth. In aviation, the altitude can have several meanings, and is always qualified by explicitly adding a modifier. Parties exchanging altitude information must be clear which definition is being used, aviation altitude is measured using either mean sea level or local ground level as the reference datum. When flying at a level, the altimeter is always set to standard pressure. On the flight deck, the instrument for measuring altitude is the pressure altimeter. There are several types of altitude, Indicated altitude is the reading on the altimeter when it is set to the local barometric pressure at mean sea level. In UK aviation radiotelephony usage, the distance of a level, a point or an object considered as a point, measured from mean sea level. Absolute altitude is the height of the aircraft above the terrain over which it is flying and it can be measured using a radar altimeter. Also referred to as radar height or feet/metres above ground level, true altitude is the actual elevation above mean sea level. It is indicated altitude corrected for temperature and pressure. Height is the elevation above a reference point, commonly the terrain elevation. Pressure altitude is used to indicate flight level which is the standard for reporting in the U. S. in Class A airspace. Pressure altitude and indicated altitude are the same when the setting is 29.92 Hg or 1013.25 millibars. Density altitude is the altitude corrected for non-ISA International Standard Atmosphere atmospheric conditions, aircraft performance depends on density altitude, which is affected by barometric pressure, humidity and temperature. On a very hot day, density altitude at an airport may be so high as to preclude takeoff and these types of altitude can be explained more simply as various ways of measuring the altitude, Indicated altitude – the altitude shown on the altimeter
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Aviation
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Aviation is the practical aspect or art of aeronautics, being the design, development, production, operation and use of aircraft, especially heavier than air aircraft. The word aviation was coined by French writer and former naval officer Gabriel La Landelle in 1863, from the verb avier, itself derived from the Latin word avis and the suffix -ation. The modern age of aviation began with the first untethered human lighter-than-air flight on November 21,1783, the practicality of balloons was limited because they could only travel downwind. It was immediately recognized that a steerable, or dirigible, balloon was required, jean-Pierre Blanchard flew the first human-powered dirigible in 1784 and crossed the English Channel in one in 1785. Rigid airships became the first aircraft to transport passengers and cargo over great distances, the best known aircraft of this type were manufactured by the German Zeppelin company. The most successful Zeppelin was the Graf Zeppelin and it flew over one million miles, including an around-the-world flight in August 1929. However, the dominance of the Zeppelins over the airplanes of that period, the Golden Age of the airships ended on May 6,1937 when the Hindenburg caught fire, killing 36 people. The cause of the Hindenburg accident was blamed on the use of hydrogen instead of helium as the lift gas. An internal investigation by the manufacturer revealed the coating used to protect the material over the frame was highly flammable. Changes to the coating formulation reduced the risk of further Hindenburg type accidents, although there have been periodic initiatives to revive their use, airships have seen only niche application since that time. In 1799 Sir George Cayley set forth the concept of the airplane as a fixed-wing flying machine with separate systems for lift, propulsion. Seven years later, on 14 October 1897, Aders Avion III was tested without success in front of two officials from the French War ministry, the report on the trials was not publicized until 1910, as they had been a military secret. In November 1906 Ader claimed to have made a flight on 14 October 1897. Although widely believed at the time, these claims were later discredited, however, the most widely accepted date is December 17,1903 by the Wright brothers. The Wright brothers were the first to fly in a powered and controlled aircraft, previous flights were gliders or free flight, but the Wright brothers combined both, setting the new standard in aviation records. Aircraft began to transport people and cargo as designs grew larger, the Wright brothers took aloft the first passenger, Charles Furnas, one of their mechanics, on May 14,1908. By the beginning of World War II, many towns and cities had built airports, the war brought many innovations to aviation, including the first jet aircraft and the first liquid-fueled rockets. Manufacturers such as Cessna, Piper, and Beechcraft expanded production to provide aircraft for the new middle-class market
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Shoe size
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A shoe size is an indication of the fitting size of a shoe for a person. There are a number of different shoe-size systems used worldwide, while all of them use a number to indicate the length of the shoe, they differ in exactly what they measure, what unit of measurement they use, and where the size 0 is positioned. Some systems also indicate the shoe width, sometimes also as a number, additionally, some regions use different shoe-size systems for different types of shoes. Foot length of the foot is measured with the subject standing barefoot, the sizes of the left and right feet are often slightly different. Each size of shoe is considered suitable for an interval of foot lengths. The inner cavity of a shoe must typically be 15–20 mm longer than the foot, a shoe-size system can refer to three characteristic lengths, The median length of feet for which a shoe is suitable. For customers, this measure has the advantage of being related to their body measures. It applies equally to any type, form, or material of shoe, however, this measure is less popular with manufacturers, because it requires them to test carefully for each new shoe model, for which range of foot sizes it is recommendable. It puts on the manufacturer the burden of ensuring that the shoe will fit a foot of a given length, the length of the inner cavity of the shoe. This measure has the advantage that it can be measured easily on the finished product, however, it will vary with manufacturing tolerances and provides the customer only very crude information about the range of foot sizes for which the shoe is suitable. The length of the last, the template over which the shoe is manufactured. This measure is the easiest one for the manufacturer to use, because it only the tool used to produce the shoe. It makes no promise about manufacturing tolerances or for what size of foot the shoe is actually suitable and it leaves all responsibility and risk of choosing the correct size with the customer. Further, the last can be measured in different ways resulting in different measurements. All these measures differ substantially from one another for the same shoe, sizing systems also differ in what units of measurement they use. This also results in different increments between shoe sizes because usually, only full or half sizes are made, the following length units are commonly used today to define shoe-size systems, The Paris point equates to 2⁄3 centimetre. This means an increment of 2⁄3 centimetre between whole sizes, and 1⁄3 centimetre between half sizes and this unit is commonly used in Continental Europe. The barleycorn is an old English unit that equates to 1⁄3 inch and this measure is the basis for current U. K. and U. S. shoe sizes, with the largest shoe size taken as twelve inches and then counting backwards in barleycorn units
23.
Ancient Egyptian units of measurement
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Egyptian Circle Egyptian units of length are attested from the Early Dynastic Period, when the Palermo stone recorded the level of the Nile River. During the reign of Pharaoh Djer, the height of the Nile was recorded as 6 cubits and 1 palm, a 3rd-dynasty diagram shows how to construct an elliptical vault using simple measures along an arc. The ostracon depicting this diagram was found near the Step Pyramid of Saqqara, a curve is divided into five sections and the height of the curve is given in cubits, palms, and digits in each of the sections. At some point, lengths were standardized by cubit rods, examples have been found in the tombs of officials, noting lengths up to remen. Royal cubits were used for land measures such as roads and fields, fourteen rods, including one double-cubit rod, were described and compared by Lepsius. Two examples are known from the Saqqara tomb of Maya, the treasurer of Tutankhamun, another was found in the tomb of Kha in Thebes. These cubits are about 52.5 cm long and are divided into palms and hands, each palm is divided into four fingers from left to right and the fingers are further subdivided into ro from right to left. The rules are divided into hands so that for example one foot is given as three hands and fifteen fingers and also as four palms and sixteen fingers. Surveying and itinerant measurement were undertaken using rods, poles, a scene in the tomb of Menna in Thebes shows surveyors measuring a plot of land using rope with knots tied at regular intervals. Similar scenes can be found in the tombs of Amenhotep-Sesi, Khaemhat, the balls of rope are also shown in New Kingdom statues of officials such as Senenmut, Amenemhet-Surer, and Penanhor. The digit was also subdivided into smaller fractions of ½, ⅓, ¼, minor units include the Middle Kingdom reed of 2 royal cubits, the Ptolemaic xylon of three royal cubits, the Ptolemaic fathom of four lesser cubits, and the kalamos of six royal cubits. Records of land area also date to the Early Dynastic Period, the Palermo stone records grants of land expressed in terms of kha and setat. Mathematical papyri also include units of area in their problems. The setat was the unit of land measure and may originally have varied in size across Egypts nomes. Later, it was equal to one square khet, where a khet measured 100 cubits, the setat could be divided into strips one khet long and ten cubit wide.25 m². A36 sq. cubit area was known as a kalamos, the uncommon bikos may have been 1½ hammata or another name for the cubit strip. The Coptic shipa was a unit of uncertain value, possibly derived from Nubia. Units of volume appear in the mathematical papyri, for example, computing the volume of a circular granary in RMP42 involves cubic cubits, khar, heqats, and quadruple heqats
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Ancient Mesopotamian units of measurement
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Ancient Mesopotamian units of measurement originated in the loosely organized city-states of Early Dynastic Sumer. Each city, kingdom and trade guild had its own standards until the formation of the Akkadian Empire when Sargon of Akkad issued a common standard and this standard was improved by Naram-Sin, but fell into disuse after the Akkadian Empire dissolved. The standard of Naram-Sin was readopted in the Ur III period by the Nanše Hymn which reduced a plethora of multiple standards to a few agreed upon common groupings, successors to Sumerian civilization including the Babylonians, Assyrians, and Persians continued to use these groupings. The systems that would become the classical standard for Mesopotamia were developed in parallel with writing during Uruk Period Sumer. Studies of protocuneiform indicate twelve separate counting systems used in Uruk, sexagesimal System S used to count slaves, animals, fish, wooden objects, stone objects, containers. The idea of a number did not yet exist, thus all quantities were written as metrological symbols. For example there was a symbol for one-sheep and another for one-day, about 600 of these metrological symbols exist, for this reason archaic Sumerian metrology is complex and not fully understood. In general however, length, volume, and mass are derived from a standard cube, called gur, filled with barley, wheat, water. The mass of a gur-cube, called gun2 is defined as the weight a laden ass can carry, however, because of the different specific gravities of these substances combined with dual numerical bases, multiple sizes of the gur-cube were used without consensus. The different gur-cubes are related by proportion, based on the water gur-cube, according to four basic coefficients and it is a Euboic Mana +1 Diesis. This standard is the reference used by archaeologists to reconstruct the system. A major improvement came in 2150 BCE during the Akkadian Empire under the reign of Naram-Sin when the systems were unified by a single official standard. His reform is considered the first standardized system of measure in Mesopotamia, the royal gur-cube was a theoretical cuboid of water approximately 6m × 6m ×0. 5m from which all other units could be derived. The Neo-Sumerians continued use of the royal gur-cube as indicated by the Letter of Nanse issued in 2000 BCE by Gudea, use of the same standard continued through the Babylonian, Assyrian, and Persian Empires. Units of Length are prefixed by the logogram DU a convention of the archaic period counting system from which it was evolved, basic length was used in architecture and field division. Distance units were geodectic as distinguished from non-geodectic basic length units, Sumerian geodesy divided latitude into seven zones between equator and pole. The GAN2 system G counting system evolved into area measurements, a special unit measuring brick quantity by area was called the brick-garden which held 720 bricks. The ± value represents 1 standard deviation, all values have been rounded to second digit of the standard deviation
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Cubit
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The cubit is an ancient unit based on the forearm length from the middle finger tip to the elbow bottom. Cubits of various lengths were employed in many parts of the world in antiquity, during the Middle Ages, the term is still used in hedge laying, the length of the forearm being frequently used to determine the interval between stakes placed within the hedge. The English word cubit comes from the Latin noun cubitus elbow, from the verb cubo, cubare, cubui, cubitum to lie down, the ancient Egyptian royal cubit is the earliest attested standard measure. Cubit rods were used for the measurement of length, a number of these rods have survived, two are known from the tomb of Maya, the treasurer of the 18th dynasty pharaoh Tutankhamun, in Saqqara, another was found in the tomb of Kha in Thebes. Fourteen such rods, including one double cubit rod, were described and compared by Lepsius in 1865. These cubit rods range from 523.5 to 529.2 mm in length, and are divided into seven palms, each palm is divided into four fingers and the fingers are further subdivided. Use of the royal cubit is also known from Old Kingdom architecture, in 1916, during the last years of the Ottoman Empire and in the middle of World War I, the German assyriologist Eckhard Unger found a copper-alloy bar while excavating at Nippur. The bar dates from c.2650 BC and Unger claimed it was used as a measurement standard and this irregularly formed and irregularly marked graduated rule supposedly defined the Sumerian cubit as about 518.6 mm. The Near Eastern or Biblical cubit is usually estimated as approximately 457.2 mm, in ancient Greek units of measurement, the standard forearm cubit measured approximately 0.46 m. The short forearm cubit, from the wrist to the elbow, in ancient Rome, according to Vitruvius, a cubit was equal to 1 1⁄2 Roman feet or 6 palm widths. Other measurements based on the length of the forearm include some lengths of ell, the Chinese chi, the Japanese shaku, the Indian hasta, the Thai sok, the Tamil, the Telugu, a cubit arm in heraldry may be dexter or sinister. It may be vested and may be shown in positions, most commonly erect. It is most often used erect as a crest, for example by the families of Poyntz of Iron Acton, Rolle of Stevenstone, the Encyclopaedia of Ancient Egyptian Architecture. The Cubit, A History and Measurement Commentary, Journal of Anthropology doi,10. 1155/2014/489757,2014 Media related to Cubit arms at Wikimedia Commons The dictionary definition of cubit at Wiktionary
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Ancient Rome
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In its many centuries of existence, the Roman state evolved from a monarchy to a classical republic and then to an increasingly autocratic empire. Through conquest and assimilation, it came to dominate the Mediterranean region and then Western Europe, Asia Minor, North Africa and it is often grouped into classical antiquity together with ancient Greece, and their similar cultures and societies are known as the Greco-Roman world. Ancient Roman civilisation has contributed to modern government, law, politics, engineering, art, literature, architecture, technology, warfare, religion, language and society. Rome professionalised and expanded its military and created a system of government called res publica, the inspiration for modern republics such as the United States and France. By the end of the Republic, Rome had conquered the lands around the Mediterranean and beyond, its domain extended from the Atlantic to Arabia, the Roman Empire emerged with the end of the Republic and the dictatorship of Augustus Caesar. 721 years of Roman-Persian Wars started in 92 BC with their first war against Parthia and it would become the longest conflict in human history, and have major lasting effects and consequences for both empires. Under Trajan, the Empire reached its territorial peak, Republican mores and traditions started to decline during the imperial period, with civil wars becoming a prelude common to the rise of a new emperor. Splinter states, such as the Palmyrene Empire, would divide the Empire during the crisis of the 3rd century. Plagued by internal instability and attacked by various migrating peoples, the part of the empire broke up into independent kingdoms in the 5th century. This splintering is a landmark historians use to divide the ancient period of history from the pre-medieval Dark Ages of Europe. King Numitor was deposed from his throne by his brother, Amulius, while Numitors daughter, Rhea Silvia, because Rhea Silvia was raped and impregnated by Mars, the Roman god of war, the twins were considered half-divine. The new king, Amulius, feared Romulus and Remus would take back the throne, a she-wolf saved and raised them, and when they were old enough, they returned the throne of Alba Longa to Numitor. Romulus became the source of the citys name, in order to attract people to the city, Rome became a sanctuary for the indigent, exiled, and unwanted. This caused a problem for Rome, which had a large workforce but was bereft of women, Romulus traveled to the neighboring towns and tribes and attempted to secure marriage rights, but as Rome was so full of undesirables they all refused. Legend says that the Latins invited the Sabines to a festival and stole their unmarried maidens, leading to the integration of the Latins, after a long time in rough seas, they landed at the banks of the Tiber River. Not long after they landed, the men wanted to take to the sea again, one woman, named Roma, suggested that the women burn the ships out at sea to prevent them from leaving. At first, the men were angry with Roma, but they realized that they were in the ideal place to settle. They named the settlement after the woman who torched their ships, the Roman poet Virgil recounted this legend in his classical epic poem the Aeneid
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Ancient Greece
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Ancient Greece was a civilization belonging to a period of Greek history from the Greek Dark Ages of the 12th-9th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and this was followed by the period of Classical Greece, an era that began with the Greco-Persian Wars, lasting from the 5th to 4th centuries BC. Due to the conquests by Alexander the Great of Macedonia, Hellenistic civilization flourished from Central Asia to the end of the Mediterranean Sea. Classical Greek culture, especially philosophy, had a influence on ancient Rome. For this reason Classical Greece is generally considered to be the culture which provided the foundation of modern Western culture and is considered the cradle of Western civilization. Classical Antiquity in the Mediterranean region is considered to have begun in the 8th century BC. Classical Antiquity in Greece is preceded by the Greek Dark Ages and this period is succeeded, around the 8th century BC, by the Orientalizing Period during which a strong influence of Syro-Hittite, Jewish, Assyrian, Phoenician and Egyptian cultures becomes apparent. The end of the Dark Ages is also dated to 776 BC. The Archaic period gives way to the Classical period around 500 BC, Ancient Periods Astronomical year numbering Dates are approximate, consult particular article for details The history of Greece during Classical Antiquity may be subdivided into five major periods. The earliest of these is the Archaic period, in which artists made larger free-standing sculptures in stiff, the Archaic period is often taken to end with the overthrow of the last tyrant of Athens and the start of Athenian Democracy in 508 BC. It was followed by the Classical period, characterized by a style which was considered by observers to be exemplary, i. e. classical, as shown in the Parthenon. This period saw the Greco-Persian Wars and the Rise of Macedon, following the Classical period was the Hellenistic period, during which Greek culture and power expanded into the Near and Middle East. This period begins with the death of Alexander and ends with the Roman conquest, Herodotus is widely known as the father of history, his Histories are eponymous of the entire field. Herodotus was succeeded by authors such as Thucydides, Xenophon, Demosthenes, Plato, most of these authors were either Athenian or pro-Athenian, which is why far more is known about the history and politics of Athens than those of many other cities. Their scope is limited by a focus on political, military and diplomatic history, ignoring economic. In the 8th century BC, Greece began to emerge from the Dark Ages which followed the fall of the Mycenaean civilization, literacy had been lost and Mycenaean script forgotten, but the Greeks adopted the Phoenician alphabet, modifying it to create the Greek alphabet. The Lelantine War is the earliest documented war of the ancient Greek period and it was fought between the important poleis of Chalcis and Eretria over the fertile Lelantine plain of Euboea. Both cities seem to have suffered a decline as result of the long war, a mercantile class arose in the first half of the 7th century BC, shown by the introduction of coinage in about 680 BC
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Nero Claudius Drusus
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Nero Claudius Drusus Germanicus, born Decimus Claudius Drusus, also called Drusus Claudius Nero, Drusus, Drusus I, Nero Drusus, or Drusus the Elder was a Roman politician and military commander. He was a patrician Claudian on his fathers side but his maternal grandmother was from a plebeian family. He was the son of Livia Drusilla and the stepson of her second husband. He launched the first major Roman campaigns across the Rhine and began the conquest of Germania, becoming the first Roman general to reach the Weser, in 12 BC, Drusus led a successful campaign into Germania, subjugating the Sicambri. Later that year he led an expedition against Germanic tribes along the North Sea coast, conquering the Batavi and the Frisii. In 11 BC, he conquered the Usipetes and the Marsi, in 10 BC, he launched a campaign against the Chatti and the resurgent Sicambri, subjugating both. The following year, while serving as consul, he conquered the Mattiaci and defeated the Marcomanni and the Cherusci, however, Drusus died later that year, depriving Rome of one of its best generals. Drusus was the youngest son of Livia Drusilla from her marriage to Tiberius Claudius Nero, Drusus was born between mid-March and mid-April 38 BC, three months after Livia married Augustus on 17 January. Gerhard Radke has proposed the date of March 28 as his most likely birthday, rumors arose that Augustus was the childs real father, although this has never been authoritatively proven. Claudius, however, encouraged the rumor during his reign as emperor to create an impression of more direct lineage from Augustus. According to Suetonius, Drusus was originally given Decimus as his praenomen, Nero was a traditional cognomen of the Claudii, whereas Drusus was given to a branch of the gens Livia. Using a cognomen such as Nero as a first name was unusual, Drusus was raised in Claudius Neros house with his brother, the future emperor Tiberius, until his legal fathers death. The two brothers developed a close relationship that would last the rest of their lives. Tiberius named his eldest son after his brother, and Drusus did likewise, Drusus married Antonia Minor, the daughter of Mark Antony and Augustus sister, Octavia Minor, and gained a reputation of being completely faithful to her. Their children were Germanicus, Claudius, a daughter named Livilla, after Drusus death, Antonia never remarried, though she outlived him by nearly five decades. Three emperors were direct descendants of Drusus, his son Claudius, his grandson Caligula, Augustus bestowed many honors on his stepsons. In 19 BC, Drusus was granted the ability to hold all public offices five years before the minimum age, when Tiberius left Italy during his term as praetor in 16 BC, Drusus legislated in his place. He became quaestor the following year, fighting against Raetian bandits in the Alps, Drusus repelled them, gaining honors, but was unable to smash their forces, and required reinforcement from Tiberius
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Charlemagne
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Charlemagne or Charles the Great, numbered Charles I, was the King of the Franks from 768, King of the Lombards from 774 and Emperor of the Romans from 800. He united much of Europe during the early Middle Ages and he was the first recognised emperor in western Europe since the fall of the Western Roman Empire three centuries earlier. The expanded Frankish state which Charlemagne founded was called the Carolingian Empire, Charlemagne was the oldest son of Pepin the Short and Bertrada of Laon. He became king in 768 following his fathers death, initially as co-ruler with his brother Carloman I, carlomans sudden death in 771 in unexplained circumstances left Charlemagne as the undisputed ruler of the Frankish Kingdom. He continued his fathers policy towards the papacy and became its protector, removing the Lombards from power in northern Italy and he campaigned against the Saxons to his east, Christianising them upon penalty of death and leading to events such as the Massacre of Verden. Charlemagne reached the height of his power in 800 when he was crowned Emperor of the Romans by Pope Leo III on Christmas Day at Old St. Peters Basilica. Charlemagne has been called the Father of Europe, as he united most of Western Europe for the first time since the Roman Empire and his rule spurred the Carolingian Renaissance, a period of energetic cultural and intellectual activity within the Western Church. All Holy Roman Emperors considered their kingdoms to be descendants of Charlemagnes empire, up to the last Emperor Francis II and these and other machinations led to the eventual split of Rome and Constantinople in the Great Schism of 1054. Charlemagne died in 814, having ruled as emperor for thirteen years and he was laid to rest in his imperial capital of Aachen in what is today Germany. He married at least four times and had three sons, but only his son Louis the Pious survived to succeed him. By the 6th century, the western Germanic Franks had been Christianised, Francia, ruled by the Merovingians, was the most powerful of the kingdoms that succeeded the Western Roman Empire. Following the Battle of Tertry the Merovingians declined into powerlessness, for which they have dubbed the rois fainéants. Almost all government powers were exercised by their chief officer, the mayor of the palace, in 687, Pepin of Herstal, mayor of the palace of Austrasia, ended the strife between various kings and their mayors with his victory at Tertry. He became the governor of the entire Frankish kingdom. Pepin was the grandson of two important figures of the Austrasian Kingdom, Saint Arnulf of Metz and Pepin of Landen, Pepin of Herstal was eventually succeeded by his illegitimate son Charles, later known as Charles Martel. After 737, Charles governed the Franks in lieu of a king, Charles was succeeded in 741 by his sons Carloman and Pepin the Short, the father of Charlemagne. In 743, the brothers placed Childeric III on the throne to curb separatism in the periphery and he was the last Merovingian king. Carloman resigned office in 746, preferring to enter the church as a monk, Pepin brought the question of the kingship before Pope Zachary, asking whether it was logical for a king to have no royal power
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Charlieu Abbey
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Charlieu Abbey or St. Fortunatus Abbey, Charlieu, located at Charlieu, Loire, Burgundy, France, was a Benedictine abbey, and later a Cluniac priory. The monastery, dedicated to Saint Fortunatus, was founded in 872, the abbey was placed under the direct control of the Holy See. Its roof was wooden, for no foundations for interior supporting piers were found, an early benefactor was Boso, Duke of Burgundy, who placed a priory in Charlieus gift when he was crowned King of Provence, the abbey long claimed that Boso was buried at Charlieu. By 926 the abbey was important enough to be the seat of a synod, the Benedictine community at Charlieu was annexed by the Cluniac movement in 932, one of Clunys earliest acquisitions and always among the first mentioned in any list of Cluniac houses. In the eleventh century the abbot was reduced to a prior, a narthex was added in the twelfth century. The community of Charlieu refused the Cluniac reforms of the seventeenth century, on 9 September 1792 a Revolutionary mob broke into the abbeys muniments room and made a bonfire of all its records
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Standard (metrology)
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In metrology, a standard is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the reference for a system of weights and measures. Historical standards for length, volume, and mass were defined by different authorities. There is a hierarchy of physical measurement standards. At the top of the tree are the master standards - these are known as primary standards, primary standards are made to the highest metrological quality and are the definitive definition or realization of their unit of measure. Historically, units of measure were defined with reference to unique artifacts which were the legal basis of units of measure. One advantage of elimination of artifact standards is that inter-comparison of artifacts is no longer required, another advantage would be that the loss or damage of the artifact standards would not disrupt the system of measures. The next quality standard in the hierarchy is known as a secondary standard, secondary standards are calibrated with reference to a primary standard. The third level of standard, a standard which is calibrated against a secondary standard, is known as a working standard. Working standards are used for the calibration of commercial and industrial measurement equipment, an example of a primary standard is the international prototype kilogram which is the master kilogram and the primary mass standard for the International System of Units. The IPK is a one kilogram mass of a platinum-iridium alloy maintained by the International Bureau of Weights and Measures in Sèvres, another example is the unit of electrical potential, the volt. Formerly it was defined in terms of standard cell electrochemical batteries, currently the volt is defined in terms of the output of a Josephson junction, which bears a direct relationship to fundamental physical constants. In contrast, the standard for the meter is no longer defined by a physical object. In 1983, the meter was redefined as the distance light travels in a vacuum during 1/299,792,458 of a second. Secondary reference standards are very close approximations of primary reference standards, working standards and certified reference materials used in commerce and industry have a traceable relationship to the secondary and primary standards. Working standards are expected to deteriorate, and are no longer considered traceable to a standard after a time period or use count expires. National organizations provide calibration and private industrial laboratories with items, processes and/or certification so they can provide certified traceability to national standards and these laboratory standards are kept in controlled conditions to maintain their precision, and used as a reference for calibration and creating working standards. Sometimes they are called secondary standards because of their high quality, history of measurement International System of Units Measurement Measurement uncertainty Measuring instrument Metre Technical standard Units of measurement Watt balance
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Royal Observatory, Greenwich
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The Royal Observatory, Greenwich is an observatory situated on a hill in Greenwich Park, overlooking the River Thames. It played a role in the history of astronomy and navigation. The observatory was commissioned in 1675 by King Charles II, with the stone being laid on 10 August. The site was chosen by Sir Christopher Wren and he appointed John Flamsteed as the first Astronomer Royal. The building was completed in the summer of 1676, the building was often called Flamsteed House, in reference to its first occupant. The scientific work of the observatory was relocated elsewhere in stages in the first half of the 20th century,1675 –22 June, Royal Observatory founded. 1675 –10 August, construction began,1714 Longitude Act established the Board of Longitude and Longitude rewards. The Astronomer Royal was, until the Board was dissolved in 1828,1767 Astronomer Royal Nevil Maskelyne began publication of the Nautical Almanac, based on observations made at the Observatory. 1833 Daily time signals began, marked by dropping a Time ball,1899 The New Physical Observatory was completed. 1924 Hourly time signals from the Royal Observatory were first broadcast on 5 February,1948 Office of the Astronomer Royal was moved to Herstmonceux. 1957 Royal Observatory completed its move to Herstmonceux, becoming the Royal Greenwich Observatory, the Greenwich site is renamed the Old Royal Observatory. Greenwich site is returned to its name, the Royal Observatory. The Ordnance Office was given responsibility for building the Observatory, with Moore providing the key instruments, Moore donated two clocks, built by Thomas Tompion, which were installed in the 20 foot high Octagon Room, the principal room of the building. They were of unusual design, each with a pendulum 13 feet in length mounted above the face, giving a period of four seconds. British astronomers have used the Royal Observatory as a basis for measurement. Four separate meridians have passed through the buildings, defined by successive instruments, subsequently, nations across the world used it as their standard for mapping and timekeeping. When the Airy circle became the reference for the meridian, the difference resulting from the change was considered enough to be neglected. When a new triangulation was done between 1936 and 1962, scientists determined that in the Ordnance Survey system the longitude of the international Greenwich meridian was not 0° and this old astronomical prime meridian has been replaced by a more precise prime meridian
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Greenwich, England
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Greenwich is an early-established district of todays London, England, centred 5.5 miles east south-east of Charing Cross. The town lends its name to the Royal Borough of Greenwich, Greenwich is generally described as being part of South-east London and sometimes as being part of East London. Greenwich is notable for its history and for giving its name to the Greenwich Meridian. The town became the site of a palace, the Palace of Placentia from the 15th century. The palace fell into disrepair during the English Civil War and was rebuilt as the Royal Naval Hospital for Sailors by Sir Christopher Wren and his assistant Nicholas Hawksmoor. These buildings became the Royal Naval College in 1873, and they remained an establishment for military education until 1998 when they passed into the hands of the Greenwich Foundation. The historic rooms within these buildings remain open to the public, other buildings are used by University of Greenwich and Trinity Laban Conservatoire of Music and Dance. The town became a resort in the 18th century and many grand houses were built there, such as Vanbrugh Castle established on Maze Hill. From the Georgian period estates of houses were constructed above the town centre, Greenwich formed part of Kent until 1889 when the County of London was created. The place-name Greenwich is first attested in a Saxon charter of 918 and it is recorded as Grenewic in 964, and as Grenawic in the Anglo-Saxon Chronicle for 1013. It is Grenviz in the Domesday Book of 1086, and Grenewych in the Taxatio Ecclesiastica of 1291, the name means green wic or settlement. An article in The Times of 13 October 1967 stated, East Greenwich, gateway to the Blackwall Tunnel, remains solidly working class, the manpower for one eighth of Londons heavy industry. West Greenwich is a hybrid, the spirit of Nelson, the Cutty Sark, the Maritime Museum, an industrial waterfront and a number of elegant houses, ripe for development. Royal charters granted to English colonists in North America, often used the name of the manor of East Greenwich for describing the tenure as that of free socage, New England charters provided that the grantees should hold their lands as of his Majesty’s manor of East Greenwich. Grants named the castle of Windsor, places in North America that have taken the name East Greenwich include a township in Gloucester County, New Jersey, a hamlet in Washington County, New York, and a town in Kent County, Rhode Island. Tumuli to the south-west of Flamsteed House, in Greenwich Park, are thought to be early Bronze Age barrows re-used by the Saxons in the 6th century as burial grounds, to the east between the Vanbrugh and Maze Hill Gates is the site of a Roman villa or temple. A small area of red paving tesserae protected by railings marks the spot and it was excavated in 1902 and 300 coins were found dating from the emperors Claudius and Honorius to the 5th century. This was excavated by the Channel 4 television programme Time Team in 1999, broadcast in 2000, the Roman road from London to Dover, Watling Street crossed the high ground to the south of Greenwich, through Blackheath
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Megalithic Yard
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A Megalithic Yard is a unit of measurement of about 2.72 feet, that some researchers believe was used in the construction of megalithic structures. The proposal was made by Alexander Thom as a result of his surveys of 600 megalithic sites in England, Scotland, Wales, Thom also proposed the Megalithic Rod of 2.5 MY. As subunits of these, he proposed the Megalithic Inch of 2.073 centimetres, one hundred of which are included in a Megalithic Rod. An oak rod from the Iron Age fortified settlement at Borre Fen mearured 53.15 inches with marks dividing it up into eight parts of 6.64 inches, euan Mackie referred to five eights of this rod 33.2 inches as very close to a megalithic yard. A hazel measuring rod recovered from a Bronze Age burial mound in Borum Eshøj, keith Critchlow suggested this may have shrunk 0.63 inches from its original length of one Megalithic Yard over a period of 3000 years. Thom made a comparison of his Megalithic Yard with the Spanish vara and he suggested similarities with other measurements such as the ancient Indian gaz and the Sumerian šu-du3-a. Along with John Michell, Mackie also noted that it is the diagonal of a rectangle measuring 2 by 1 Egyptian remens, jay Kappraff has noted similarity between the Megalithic Yard and the ancient Indus short yard of 33 inches. Anne Macaulay reported that the Megalithic Rod is equal in length to the Greek fathom of from studies by Eric Fernie of the Metrological Relief in the Ashmolean Museum, thoms proposals were initially ignored or regarded as unbelievable by mainstream archaeologists. Clive Ruggles, citing astronomer Douglas C, in other words, the evidence presented by Thom could be adequately explained by, say, monuments being set out by pacing, with the unit reflecting an average length of pace. In an investigation for the Royal Academy Kendall concluded that there was evidence of a unit in Scottish circles but not in English circles. Statistician P. R. Freeman reached similar conclusions and found two other units fit the data as well as the yard. In his book Rings of Stone, The Prehistoric Stone Circles of Britain, aubrey Burl calls the megalithic yard a chimera, a grotesque statistical misconception. Most researchers have concluded there is marginal evidence for a standardized measuring unit. John Ivimy noted that The ratio MY, Rc is SQRT, SQRT to the nearest millimeter, which makes the MY equal to SQRT remens, or the length of a 2 x 1 remen rectangle
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Welsh legend
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Welsh mythology consists of both folk traditions developed in Wales, and traditions developed by the Celtic Britons elsewhere before the end of the first millennium. Like most predominately oral societies found in the prehistoric Britain, Welsh mythology and this oral record has been lost or altered as result of outside contact and invasion over the years. The only character to appear in every branch is Pryderi fab Pwyll, the king of Dyfed, who is born in the first Branch, is killed in the fourth, and is probably a reflex of the Celtic god Maponos. The only other recurring characters are Pryderis mother Rhiannon, associated with the peaceful British prince Manawydan and he manages to win her hand at the expense of Gwawl, to whom she is betrothed, and she bears him a son, but the child disappears soon after his birth. Rhiannon is accused of killing him and forced to carry guests on her back as punishment. The child has been taken by a monster, and is rescued by Teyrnon and his wife and they return him to his real parents, Rhiannon is released from her punishment, and the boy is renamed Pryderi. In the second branch, Branwen, sister of Brân the Blessed, king of Britain, is given in marriage to Matholwch, Matholwch and Branwen have a son, Gwern, but Matholwch proceeds to mistreat Branwen, beating her and making her a drudge. Branwen trains a starling to take a message to Bran, who goes to war against Matholwch and his army crosses the Irish Sea in ships, but Brân is so huge he wades across. The Irish offer to make peace, and build a big enough to entertain Bran, but inside they hang a hundred bags, telling Efnysien they contain flour. Efnysien kills the warriors by squeezing the bags, later, at the feast, Efnysien throws Gwern on the fire and fighting breaks out. Seeing that the Irish are using the cauldron to revive their dead, Efnysien hides among the corpses and destroys the cauldron, only seven men, all Britons, survive the battle, including Pryderi, Manawyddan and Bran, who is mortally wounded by a poisoned spear. Brân asks his companions to cut off his head and take it back to Britain, Branwen dies of grief on returning home. Five pregnant women survive to repopulate Ireland, Pryderi and Manawydan return to Dyfed, where Pryderi marries Cigfa and Manawydan marries Rhiannon. However, a mist descends on the land, leaving it empty, eventually they return to Dyfed and become hunters again. While hunting, a white boar leads them to a mysterious castle, Pryderi, against Manawydans advice, goes inside, but does not return. Rhiannon goes to investigate and finds him clinging to a bowl, the same fate befalls her, and the castle disappears. Manawydan and Cigfa return to England as shoemakers, but once again the locals drive them out and they sow three fields of wheat, but the first field is destroyed before it can be harvested. The next night the field is destroyed
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Belgae
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They were discussed in depth by Julius Caesar in his account of his wars in Gaul. Some peoples in Britain were also called Belgae and ORahilly equated them with the Fir Bolg in Ireland, the Belgae gave their name to the Roman province of Gallia Belgica and, much later, to the modern country of Belgium. Thus, a Proto-Celtic ethnic name *Bolgī could be interpreted as The People who Swell, each of these three parts was different in terms of customs, laws, and language. Ancient sources such as Caesar are not always clear about the used to define ethnicity today. The fact that the Belgae were living in Gaul means that in one sense they were Gauls and this may be Caesars meaning when he says The Belgae have the same method of attacking a fortress as the rest of the Gauls. Some translators of Caesar have given crucially different interpretations of his meaning in another passage on the Belgae, W. A. McDevitte and W. S. Bohn rendered the Latin of Caesar in Bello Gallico, II.4 as When Caesar inquired. So Caesars use of the word Germani needs special consideration and he describes a grouping of tribes within the Belgic alliance as the Germani, distinguishing them from their neighbours. The most important in his battles were the Eburones, the other way he uses the term is to refer to any tribe considered to be of similar ancestry and traditions, with ancestry east of the Rhine. So the Germani amongst the Belgae were called Germani cisrhenani, to them from other Germani, such as those living on the east of the Rhine. The later historian Tacitus was informed that the name Germania was recent in his day, the first people to cross the Rhine and oust the Gauls, those now called Tungri, were then called Germani. It was the name of nation, not a race. And so, to begin with, they were all called Germani after the conquerors because of the terror these inspired, and then, once the name had been devised, they adopted it themselves. In other words, the collective name Germani had first been used by the Gauls or Belgae for the intruders from beyond the Rhine, many modern scholars believe that the Belgae were a firmly Celtic-speaking group. For example, Maurits Gysseling, suggest that prior to Celtic and Germanic influences the Belgae may have comprised a distinct Indo-European branch, surviving inscriptions also indicate that Gaulish was spoken in at least part of Belgic territory. The Romans were not precise in their ethnography of northern barbarians, by Germanic, the east of the Rhine was not necessarily inhabited by Germanic speakers at this time. It has been remarked that Germanic language speakers might have been no closer than the river Elbe in the time of Caesar, the sound changes described by Grimms law appear to have affected names with older forms, apparently already in the second century BC. Strong evidence for old Celtic placenames, though, is found in the Ardennes, according to Strabo, the country of the Belgae extended along the coast where 15 tribes were living from the Rhenus to the Liger. Apart from the Germani, the report of Caesar seems to indicate that more of the Belgae had some Germanic ancestry and ethnicity, other tribes that may have been included among the Belgae in some contexts were the Leuci, Treveri, and Mediomatrici
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Anglo-Saxons
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The Anglo-Saxons are a people who have inhabited Great Britain from the 5th century. Historically, the Anglo-Saxon period denotes the period in Britain between about 450 and 1066, after their settlement and up until the Norman conquest. The early Anglo-Saxon period includes the creation of an English nation, with many of the aspects that survive today, including government of shires. During this period, Christianity was re-established and there was a flowering of literature, charters and law were also established. The term Anglo-Saxon is popularly used for the language that was spoken and written by the Anglo-Saxons in England, in scholarly use, it is more commonly called Old English. The history of the Anglo-Saxons is the history of a cultural identity and it developed from divergent groups in association with the peoples adoption of Christianity, and was integral to the establishment of various kingdoms. Threatened by extended Danish invasions and occupation of eastern England, this identity was re-established, the visible Anglo-Saxon culture can be seen in the material culture of buildings, dress styles, illuminated texts and grave goods. Behind the symbolic nature of these emblems, there are strong elements of tribal. The elite declared themselves as kings who developed burhs, and identified their roles and peoples in Biblical terms, above all, as Helena Hamerow has observed, local and extended kin groups remained. the essential unit of production throughout the Anglo-Saxon period. Use of the term Anglo-Saxon assumes that the words Angles, Saxons or Anglo-Saxon have the meaning in all the sources. Assigning ethnic labels such as Anglo-Saxon is fraught with difficulties and this term began to be used only in the 8th century to distinguish the Germanic groups in Britain from those on the continent. The Old English ethnonym Angul-Seaxan comes from the Latin Angli-Saxones and became the name of the peoples Bede calls Anglorum, Anglo-Saxon is a term that was rarely used by Anglo-Saxons themselves, it is not an autonym. It is likely they identified as ængli, Seaxe or, more probably, also, the use of Anglo-Saxon disguises the extent to which people identified as Anglo-Scandinavian after the Viking age or the conquest of 1016, or as Anglo-Norman after the Norman conquest. The earliest historical references using this term are from outside Britain, referring to piratical Germanic raiders, Saxones who attacked the shores of Britain, procopius states that Britain was settled by three races, the Angiloi, Frisones, and Britons. The term Angli Saxones seems to have first been used in writing of the 8th century. The name therefore seemed to mean English Saxons, the Christian church seems to have used the word Angli, for example in the story of Pope Gregory I and his remark, Non Angli sed angeli. The terms ænglisc and Angelcynn were also used by West Saxon King Alfred to refer to the people, at other times he uses the term rex Anglorum, which presumably meant both Anglo-Saxons and Danes. Alfred the Great used Anglosaxonum Rex, the term Engla cyningc is used by Æthelred
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Roman conquest of England
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The Roman conquest of Britain was a gradual process, beginning effectively in AD43 under Emperor Claudius, whose general Aulus Plautius served as first governor of Roman Britain. Great Britain had already frequently been the target of invasions, planned and actual, by forces of the Roman Republic and Roman Empire. Between 55 BC and the 40s AD, the status quo of tribute, hostages, augustus prepared invasions in 34 BC,27 BC and 25 BC. The first and third were called off due to revolts elsewhere in the empire, by the 40s AD, the political situation within Britain was apparently in ferment. Modern historians are unsure if that was meant to be a punishment for the soldiers mutiny or due to Caligulas derangement. Certainly this invasion attempt readied the troops and facilities that would make Claudius invasion possible three years later, for example, Caligula built a lighthouse at Bononia that provided a model for the one built soon after at Dubris. Three years later, in 43, possibly by re-collecting Caligulas troops, Claudius mounted a force to re-instate Verica. Aulus Plautius, a senator, was given overall charge of four legions, totalling about 20,000 men. The legions were, Legio II Augusta Legio IX Hispana Legio XIV Gemina Legio XX Valeria Victrix The II Augusta is known to have been commanded by the future emperor Vespasian. Three other men of rank to command legions are known from the sources to have been involved in the invasion. Cassius Dio mentions Gnaeus Hosidius Geta, who led the IX Hispana. He wrote that Sabinus was Vespasians lieutenant, but as Sabinus was the brother and preceded Vespasian into public life. Eutropius mentions Gnaeus Sentius Saturninus, although as a former consul he may have been too senior, the main invasion force under Aulus Plautius crossed in three divisions. The port of departure is usually taken to have been Boulogne, neither of these locations is certain. Richborough has a natural harbour which would have been suitable. However, Dio says the Romans sailed east to west, some historians suggest a sailing from Boulogne to the Solent, landing in the vicinity of Noviomagus or Southampton, in territory formerly ruled by Verica. An alternative explanation might be a sailing from the mouth of the Rhine to Richborough, British resistance was led by Togodumnus and Caratacus, sons of the late king of the Catuvellauni, Cunobeline. A substantial British force met the Romans at a river crossing thought to be near Rochester on the River Medway, the battle raged for two days
