Polar motion | Earth's axis, wobble, precession | Britannica". www.britannica.com . Retrieved 27 August 2023. Seventeen years after Bessel calculated his ellipsoid of reference, some of the meridian arcs the German astronomer had used for his calculation had been enlarged. This was a very important circumstance because the influence of errors due to vertical deflections was minimized in proportion to the length of the meridian arcs: the longer the meridian arcs, the more precise the image of the Earth ellipsoid would be. [28] After Stuve Geodetic Arc measurement, it was resolved in the 1860s, at the initiative of Carlos Ibáñez e Ibáñez de Ibero who would become the first president of both the International Geodetic Association and the International Committee for Weights and Measure, to remeasure the arc of meridian from Dunkirk to Formentera and to extend it from Shetland to the Sahara. [67] [68] [69] [66] This did not pave the way to a new definition of the metre because it was known that the theoretical definition of the metre had been inaccessible and misleading at the time of Delambre and Mechain arc measurement, as the geoid is a ball, which on the whole can be assimilated to an oblate spheroid, but which in detail differs from it so as to prohibit any generalization and any extrapolation from the measurement of a single meridian arc. [26] In 1859, Friedrich von Schubert demonstrated that several meridians had not the same length, confirming an hypothesis of Jean Le Rond d’Alembert. He also proposed an ellipsoid with three unequal axes. [70] [71] In 1860, Elie Ritter, a mathematician from Geneva, using Schubert's data computed that the Earth ellipsoid could rather be a spheroid of revolution accordingly to Adrien-Marie Legendre’s model. [72] However, the following year, resuming his calculation on the basis of all the data available at the time, Ritter came to the conclusion that the problem was only resolved in an approximate manner, the data appearing too scant, and for some affected by vertical deflections, in particular the latitude of Montjuïc in the French meridian arc which determination had also been affected in a lesser proportion by systematic errors of the repeating circle. [73] [74] [26] Judson, Lewis V. (1 October 1976) [1963]. Barbrow, Louis E. (ed.). Weights and Measures Standards of the United States, a brief history. Derived from a prior work by Louis A. Fisher (1905). US: US Department of Commerce, National Bureau of Standards. doi: 10.6028/NBS.SP.447. LCCN 76-600055. NBS Special Publication 447; NIST SP 447; 003-003-01654-3.

a b c "Histoire du mètre". Direction Générale des Entreprises (DGE) (in French) . Retrieved 16 May 2019. Brunner, Jean (1857). "Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels". Gallica (in French). pp.150–153 . Retrieved 15 May 2019. Lettres philosophiques/Lettre 15 - Wikisource". fr.wikisource.org (in French) . Retrieved 7 October 2023.LED aluminium profiles are great for adding lighting to your home in places you didn’t think were possible. This is due to the protective nature that the aluminium provides to the LED bulbs, giving them protection from humidity, moisture, water, dirt and heat too all whilst looking the part too. Below are some of the reasons for using LED aluminium profiles in your home. Tables come in all shapes, lengths and colors so we can’t say all tables are 1 meter across. However, most square or rectangular lounge and kitchen tables are a standard size whose width is about 1 meter. a b c Quinn, T. J. (2012). From artefacts to atoms: the BIPM and the search for ultimate measurement standards. Oxford. pp.20, 37–38, 91–92, 70–72, 114–117, 144–147, 8. ISBN 978-0-19-990991-9. OCLC 861693071. {{ cite book}}: CS1 maint: location missing publisher ( link) a b Parr, Albert C. (1 April 2006). "A Tale About the First Weights and Measures Intercomparison in the United States in 1832". Journal of Research of the National Institute of Standards and Technology. 111 (1): 31–32, 36. doi: 10.6028/jres.111.003. PMC 4654608. PMID 27274915– via NIST.

a b von Struve, Friedrich Georg Wilhelm (July 1857). "Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels". Gallica. p.509, 510 . Retrieved 30 August 2021. In 1799, a commission including Johan Georg Tralles, Jean Henri van Swinden, Adrien-Marie Legendre and Jean-Baptiste Delambre calculated the distance from Dunkirk to Barcelona using the data of the triangulation between these two towns and determined the portion of the distance from the North Pole to the Equator it represented. Pierre Méchain's and Jean-Baptiste Delambre's measurements were combined with the results of the Spanish-French geodetic mission and a value of 1 / 334 was found for the Earth's flattening. However, French astronomers knew from earlier estimates of the Earth's flattening that different meridian arcs could have different lengths and that theire curvature could be irregular. The distance from the North Pole to the Equator was then extrapolated from the measurement of the Paris meridian arc between Dunkirk and Barcelona and was determined as 5 130 740 toises. As the metre had to be equal to one ten-millionth of this distance, it was defined as 0.513074 toise or 3 feet and 11.296 lines of the Toise of Peru, which had been constructed in 1735 for the French Geodesic Mission to the Equator. When the final result was known, a bar whose length was closest to the meridional definition of the metre was selected and placed in the National Archives on 22 June 1799 (4 messidor An VII in the Republican calendar) as a permanent record of the result. [48] [24] [42] [45] [49] [50] [51] Early adoption of the metre as a scientific unit of length: the forerunners [ edit ] Triangulation near New York City, 1817In 1830, Hassler became head of the Office of Weights and Measures, which became a part of the Survey of the Coast. He compared various units of length used in the United States at that time and measured coefficients of expansion to assess temperature effects on the measurements. [54] a b Martina Schiavon. La geodesia y la investigación científica en la Francia del siglo XIX: la medida del arco de meridiano franco-argelino (1870-1895). Revista Colombiana de Sociología, 2004, Estudios sociales de la ciencia y la tecnologia, 23, pp.11-30. Defines the metre as the length of the path travelled by light in a vacuum during a time interval of 1 / 299 792 458 of a second. [133] [134]

Bessel, Friedrich Wilhelm (1 April 1840). "Über das preufs. Längenmaaß und die zu seiner Verbreitung durch Copien ergriffenen Maaßregeln". Astronomische Nachrichten. 17 (13): 193. Bibcode: 1840AN.....17..193B. doi: 10.1002/asna.18400171302. ISSN 0004-6337. A more detailed listing of errors can be found in Beers, John S; Penzes, William B (December 1992). "§4 Re-evaluation of measurement errors" (PDF). NIST length scale interferometer measurement assurance; NIST document NISTIR 4998. pp.9 ff . Retrieved 17 December 2011.

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a b c Soler, T. (1 February 1997). "A profile of General Carlos Ibáñez e Ibáñez de Ibero: first president of the International Geodetic Association". Journal of Geodesy. 71 (3): 176–188. Bibcode: 1997JGeod..71..176S. CiteSeerX 10.1.1.492.3967. doi: 10.1007/s001900050086. ISSN 1432-1394. S2CID 119447198.

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Current use: The centimeter, like the meter, is used in all sorts of applications worldwide (in countries that have undergone metrication) in instances where a smaller denomination of the meter is required. Height is commonly measured in centimeters outside of countries like the United States. Arnold Dieter (1991). Building in Egypt: pharaonic stone masonry. Oxford: Oxford University Press. ISBN 978-0-19-506350-9. p.251. a b c Clarke, Alexander Ross (1873), "XIII. Results of the comparisons of the standards of length of England, Austria, Spain, United States, Cape of Good Hope, and of a second Russian standard, made at the Ordnance Survey Office, Southampton. With a preface and notes on the Greek and Egyptian measures of length by Sir Henry James", Philosophical Transactions, London, vol.163, p.463, doi: 10.1098/rstl.1873.0014 Base unit definitions: Meter". National Institute of Standards and Technology . Retrieved 28 September 2010. To further reduce uncertainty, the 17th CGPM in 1983 replaced the definition of the metre with its current definition, thus fixing the length of the metre in terms of the second and the speed of light: [112] [113] The metre is the length of the path travelled by light in vacuum during a time interval of 1 / 299 792 458 of a second.