118 relations: Albert A. Michelson, Ammeter, An Essay towards a Real Character, and a Philosophical Language, Archives Nationales (France), Astronomical unit, Atmospheric pressure, Atom, Atomic clock, Barcelona, Base unit (measurement), Brass, Cambridge University Press, Carlos Ibáñez e Ibáñez de Ibero, Centimetre, Christiaan Huygens, Christopher Wren, Circular sector, Conversion of units, Cubit, Decametre, Decimetre, Dunkirk, Dutch units of measurement, Electromagnetic radiation, Electromagnetic spectrum, Ell, Equator, Femtometre, Flattening, Foot (unit), French Academy of Sciences, French Revolution, Friedrich Bessel, Gabriel Mouton, General Conference on Weights and Measures, General relativity, Geoid, Gravity, Hectometre, Helium–neon laser, History of the metre, Houghton Mifflin Harcourt, Hyperfine structure, Imperial units, Inch, Interferometry, International Association of Geodesy, International Bureau of Weights and Measures, International Committee for Weights and Measures, International System of Units, ..., Introduction to the metric system, Iridium, ISO 1, Isotopes of krypton, Jean Baptiste Joseph Delambre, Johann Jacob Baeyer, John Wilkins, Joseph Needham, Kilometre, Krypton, Least count, Length, Length measurement, Light, Light-year, Line (unit), Meridian (geography), Meridian arc, Mesures usuelles, Metre Convention, Metric prefix, Metric system, Metrication, Micrometre, Millimetre, Mnemonic, Montjuïc Castle, Nanometre, National Assembly (French Revolution), National Convention, National Institute of Standards and Technology, North Pole, Orange (colour), Orders of magnitude (length), Oxford English Dictionary, Oxford University Press, Paris meridian, Parsec, Pendulum, Philippine English, Picometre, Pierre Méchain, Pittacus of Mytilene, Platinum, Proper length, Red, Refractive index, Sèvres, Scandinavian mile, Science and Civilisation in China, Scientific notation, Second, Seconds pendulum, SI base unit, Spectral line, Speed of light, Speedometer, Sphere, Spheroid, Tito Livio Burattini, Unit of measurement, United States customary units, United States Department of Commerce, Vacuum, Verst, Vertical metre, Wavelength, Yard. Expand index (68 more) » « Shrink index
Albert Abraham Michelson FFRS HFRSE (December 19, 1852 – May 9, 1931) was an American physicist known for his work on measuring the speed of light and especially for the Michelson–Morley experiment.
An ammeter (from Ampere Meter) is a measuring instrument used to measure the current in a circuit.
An Essay towards a Real Character, and a Philosophical Language (London, 1668) is the best-remembered of the numerous works of John Wilkins, in which he expounds a new universal language, meant primarily to facilitate international communication among scholars, but envisioned for use by diplomats, travelers, and merchants as well.
The Archives Nationales (Archives nationales de France), also known as the French Archives or the National Archives, preserve France's official archives apart from the archives of the Ministry of Defence and the Ministry of Foreign Affairs, as these two ministries have their own archive services, the Defence Historical Service (Service historique de la défense) and the Diplomatic Archives (Archives diplomatiques) respectively.
The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun.
Atmospheric pressure, sometimes also called barometric pressure, is the pressure within the atmosphere of Earth (or that of another planet).
An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element.
An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.
Barcelona is a city in Spain.
A base unit (also referred to as a fundamental unit) is a unit adopted for measurement of a base quantity.
Brass is a metallic alloy that is made of copper and zinc.
Cambridge University Press (CUP) is the publishing business of the University of Cambridge.
Carlos Ibáñez e Ibáñez de Ibero, 1st Marquis of Mulhacén, (April 14, 1825 - January 28 or 29, 1891) was a Spanish divisional general and geographer.
A centimetre (international spelling as used by the International Bureau of Weights and Measures; symbol cm) or centimeter (American spelling) is a unit of length in the metric system, equal to one hundredth of a metre, centi being the SI prefix for a factor of.
Christiaan Huygens (Hugenius; 14 April 1629 – 8 July 1695) was a Dutch physicist, mathematician, astronomer and inventor, who is widely regarded as one of the greatest scientists of all time and a major figure in the scientific revolution.
Sir Christopher Wren PRS FRS (–) was an English anatomist, astronomer, geometer, and mathematician-physicist, as well as one of the most highly acclaimed English architects in history.
A circular sector or circle sector (symbol: ⌔), is the portion of a disk enclosed by two radii and an arc, where the smaller area is known as the minor sector and the larger being the major sector.
Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors.
The cubit is an ancient unit of length that had several definitions according to each of the various different cultures that used the unit.
A decametre or dekametre (American spelling: decameter, earlier dekameter; symbol dam,, This measure is included in the SI mostly for completeness: in principle, any combination of prefix and unit can be written, but many are rarely used in practice. One practical use of the decameter is for altitude of geopotential heights in meteorology. Meteorologists also use another seldom encountered SI prefix: hecto- in hectopascal (hPa). The volumetric form (see below) cubic decametre is convenient for describing large volumes of water such as in rivers and lakes. The square decametre (dam2) also known as the are (a), is the basis for the hectare (100 dam2), the standard metric unit of land registry.
The decimetre (SI symbol dm) is a unit of length in the metric system, equal to one tenth of a metre (the International System of Units base unit of length), ten centimetres or 1/0.254 (approximately 3.93700787) inches.
Dunkirk (Dunkerque; Duinkerke(n)) is a commune in the Nord department in northern France.
The Dutch units of measurement used today are those of the metric system.
In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.
An ell (from Proto-Germanic *alinō, cognate with Latin ulna) is a unit of measurement, originally a cubit, i.e., approximating the length of a man's arm from the elbow (literally meant the bend (bow) of the arm (ell)) to the tip of the middle finger, or about 18 inches (457 mm); in later usage, any of several longer units.
An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel).
The femtometre (American spelling femtometer, symbol fm derived from the Danish and Norwegian word femten, "fifteen"+Ancient Greek: μέτρον, metrοn, "unit of measurement") is an SI unit of length equal to 10−15 metres, which means a quadrillionth of one.
Flattening is a measure of the compression of a circle or sphere along a diameter to form an ellipse or an ellipsoid of revolution (spheroid) respectively.
The foot (feet; abbreviation: ft; symbol: ′, the prime symbol) is a unit of length in the imperial and US customary systems of measurement.
The French Academy of Sciences (French: Académie des sciences) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research.
The French Revolution (Révolution française) was a period of far-reaching social and political upheaval in France and its colonies that lasted from 1789 until 1799.
Friedrich Wilhelm Bessel (22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist and geodesist.
Gabriel Mouton (1618 – 28 September 1694) was a French abbot and scientist.
The General Conference on Weights and Measures (Conférence générale des poids et mesures – CGPM) is the supreme authority of the International Bureau of Weights and Measures (Bureau international des poids et mesures – BIPM), the inter-governmental organization established in 1875 under the terms of the Metre Convention (Convention du Mètre) through which Member States act together on matters related to measurement science and measurement standards.
General relativity (GR, also known as the general theory of relativity or GTR) is the geometric theory of gravitation published by Albert Einstein in 1915 and the current description of gravitation in modern physics.
The geoid is the shape that the surface of the oceans would take under the influence of Earth's gravity and rotation alone, in the absence of other influences such as winds and tides.
Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward (or gravitate toward) one another.
The hectometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: hm) or hectometer (American spelling) is an uncommonly used unit of length in the metric system, equal to one hundred metres.
A helium–neon laser or HeNe laser, is a type of gas laser whose gain medium consists of a mixture of 85% helium and 15% neon inside of a small electrical discharge.
In the aftermath of the French Revolution (1789), the traditional units of measure used in the Ancien Régime were replaced.
Houghton Mifflin Harcourt (HMH) is an educational and trade publisher in the United States.
In atomic physics, hyperfine structure refers to small shifts and splittings in the energy levels of atoms, molecules and ions, due to interaction between the state of the nucleus and the state of the electron clouds.
The system of imperial units or the imperial system (also known as British Imperial or Exchequer Standards of 1825) is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced.
The inch (abbreviation: in or &Prime) is a unit of length in the (British) imperial and United States customary systems of measurement now formally equal to yard but usually understood as of a foot.
Interferometry is a family of techniques in which waves, usually electromagnetic waves, are superimposed causing the phenomenon of interference in order to extract information.
The International Association of Geodesy is a constituent Association of the International Union of Geodesy and Geophysics.
The International Bureau of Weights and Measures (Bureau international des poids et mesures) is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.
The International Committee for Weights and Measures (abbreviated CIPM from the French Comité international des poids et mesures) consists of eighteen persons, each of a different nationality, from Member States of the Metre Convention (Convention du Mètre) appointed by the General Conference on Weights and Measures (CGPM) whose principal task is to promote worldwide uniformity in units of measurement by taking direct action or by submitting proposals to the CGPM.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
The metric system was developed during the French Revolution to replace the various measures previously used in France.
Iridium is a chemical element with symbol Ir and atomic number 77.
ISO 1 is an international standard set by the International Organization for Standardization that specifies the standard reference temperature for geometrical product specification and verification.
There are 33 known isotopes of krypton (36Kr) with atomic mass numbers from 69 through 101.
Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician and astronomer.
Johann Jacob Baeyer (born 5 November 1794 in Berlin, died 10 September 1885 in Berlin) was a German geodesist and a lieutenant-general in the Royal Prussian Army.
John Wilkins, (16141672) was an Anglican clergyman, natural philosopher and author, and was one of the founders of the Royal Society.
Noel Joseph Terence Montgomery Needham (9 December 1900 – 24 March 1995) was a British biochemist, historian and sinologist known for his scientific research and writing on the history of Chinese science and technology.
The kilometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: km; or) or kilometer (American spelling) is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the road network of the United Kingdom where the statute mile is the official unit used.
Krypton (from translit "the hidden one") is a chemical element with symbol Kr and atomic number 36.
In metrology, the least count of a measuring instrument is the smallest change in the measured quantity that can be resolved on the instrument's scale.
In geometric measurements, length is the most extended dimension of an object.
Length measurement is implemented in practice in many ways.
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.
The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.
The line (abbreviated L or l or ‴) was a small English unit of length, variously reckoned as,,, or of an inch.
A (geographical) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude.
In geodesy, a meridian arc measurement is the distance between two points with the same longitude, i.e., a segment of a meridian curve or its length.
Mesures usuelles (customary measurements) were a system of measurement introduced by Napoleon I in 1812 to act as compromise between the metric system and traditional measurements.
The Metre Convention (Convention du Mètre), also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations (Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Turkey, United States of America, and Venezuela).
A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit.
The metric system is an internationally adopted decimal system of measurement.
Metrication or metrification is conversion to the metric system of units of measurement.
The micrometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is an SI derived unit of length equaling (SI standard prefix "micro-".
The millimetre (International spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length.
A mnemonic (the first "m" is silent) device, or memory device, is any learning technique that aids information retention or retrieval (remembering) in the human memory.
Montjuïc Castle (Castell de Montjuïc, Castillo de Montjuich) is an old military fortress, with roots dating back from 1640, built on top of Montjuïc hill in Barcelona, Catalonia, Spain.
The nanometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American spelling) is a unit of length in the metric system, equal to one billionth (short scale) of a metre (m).
During the French Revolution, the National Assembly (Assemblée nationale), which existed from 13 June 1789 to 9 July 1789, was a revolutionary assembly formed by the representatives of the Third Estate of the Estates-General; thereafter (until replaced by the Legislative Assembly on 30 Sept 1791) it was known as the National Constituent Assembly (Assemblée nationale constituante), though popularly the shorter form persisted.
The National Convention (Convention nationale) was the first government of the French Revolution, following the two-year National Constituent Assembly and the one-year Legislative Assembly.
The National Institute of Standards and Technology (NIST) is one of the oldest physical science laboratories in the United States.
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is (subject to the caveats explained below) defined as the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface.
Orange is the colour between yellow and red on the spectrum of visible light.
The following are examples of orders of magnitude for different lengths.
The Oxford English Dictionary (OED) is the main historical dictionary of the English language, published by the Oxford University Press.
Oxford University Press (OUP) is the largest university press in the world, and the second oldest after Cambridge University Press.
The Paris meridian is a meridian line running through the Paris Observatory in Paris, France—now longitude 2°20′14.03″ east.
The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System.
A pendulum is a weight suspended from a pivot so that it can swing freely.
Philippine English is any variety of English (similar and related to English) native to the Philippines, including those used by the media and the vast majority of educated Filipinos.
The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the metric system, equal to, or one trillionth of a metre, which is the SI base unit of length.
Pierre François André Méchain (16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep sky objects and comets.
Pittacus (Πιττακός; 640 – 568 BC) was an ancient Mytilenaen military general and one of the Seven Sages of Greece.
Platinum is a chemical element with symbol Pt and atomic number 78.
Proper length or rest length refers to the length of an object in the object's rest frame.
Red is the color at the end of the visible spectrum of light, next to orange and opposite violet.
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how light propagates through that medium.
Sèvres is a commune in the southwestern suburbs of Paris, France.
A Scandinavian mile (Norwegian and mil,, like "meal") is a unit of length common in Norway and Sweden, but not Denmark.
Science and Civilisation in China (1954–) is a series of books initiated and edited by British biochemist, historian and sinologist Joseph Needham, Ph.D (1900–1995).
Scientific notation (also referred to as scientific form or standard index form, or standard form in the UK) is a way of expressing numbers that are too big or too small to be conveniently written in decimal form.
The second is the SI base unit of time, commonly understood and historically defined as 1/86,400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each.
A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and one second for the return swing, a frequency of 1/2 Hz.
The International System of Units (SI) defines seven units of measure as a basic set from which all other SI units can be derived.
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies.
The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.
A speedometer or a speed meter is a gauge that measures and displays the instantaneous speed of a vehicle.
A sphere (from Greek σφαῖρα — sphaira, "globe, ball") is a perfectly round geometrical object in three-dimensional space that is the surface of a completely round ball (viz., analogous to the circular objects in two dimensions, where a "circle" circumscribes its "disk").
A spheroid, or ellipsoid of revolution, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters.
Tito Livio Burattini (Tytus Liwiusz Burattini, 8 March 1617 – 17 November 1681) was an inventor, architect, Egyptologist, scientist, instrument-maker, traveller, engineer, and nobleman.
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 kind of quantity.
United States customary units are a system of measurements commonly used in the United States.
The United States Department of Commerce is the Cabinet department of the United States government concerned with promoting economic growth.
Vacuum is space devoid of matter.
A verst (верста, versta) is an obsolete Russian unit of length.
A vertical metre is the metric unit used to measure the difference in height between two points on the terrain.
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
The yard (abbreviation: yd) is an English unit of length, in both the British imperial and US customary systems of measurement, that comprises 3 feet or 36 inches.
Attometer, Exameter, Measurement System in Meters, Meter, Meter (distance), Meter (m), Meter (unit of length), Meter (unit), Meter unit, Meters, Metre (unit), Metres, Metrical form, Petameter, Standard metre, Terameter, Zettameter.