History of the metre

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interfering influence of temperature revealed clearly the importance they attached to the expansion-induced errors. It was common knowledge, for instance, that effective measurements were possible only inside a building, the rooms of which were well protected against the changes in outside temperature, and the very presence of the observer created an interference against which it was often necessary to take strict precautions. Thus, the Contracting States also received a collection of thermometers whose accuracy made it possible to ensure that of length measurements. The international prototype would also be a "line standard"; that is, the metre was defined as the distance between two lines marked on the bar, so avoiding the wear problems of end standards.

1046: 1088:– decided that the new measure should be equal to one ten-millionth of the distance from the North Pole to the Equator (the quadrant of the Earth's circumference), measured along the meridian passing through Paris. Apart from the obvious consideration of safe access for French surveyors, the Paris meridian was also a sound choice for scientific reasons: a portion of the quadrant from Dunkirk to Barcelona (about 1000 km, or one-tenth of the total) could be surveyed with start- and end-points at sea level, and that portion was roughly in the middle of the quadrant, where the effects of the Earth's oblateness were expected not to have to be accounted for. The expedition would take place after the 1113: 2233:, while expanding it and making it international. Not, as it was mistakenly assumed for a certain time, that the Association had the unscientific thought of modifying the length of the metre, in order to conform exactly to its historical definition according to the new values that would be found for the terrestrial meridian. But, busy combining the arcs measured in the different countries and connecting the neighbouring triangulations, geodesists encountered, as one of the main difficulties, the unfortunate uncertainty which reigned over the equations of the units of length used. 870: 1712: 1829: 2365: 2737: 1617: 22: 1482: 1197: 1399: 338: 1023: 2277: 2852: 235: 3034: 975: 2438: 5336: 4303: 602: 2678:, and was consecrated as the international prototype metre at the first meeting of the CGPM in 1889. The other bars, duly calibrated against the international prototype, were distributed to the signatory nations of the Metre Convention for use as national standards. For example, the United States received No. 27 with a calibrated length of 1505:, Hassler had brought a standard metre made in Paris to the United States in 1805. He designed a baseline apparatus which instead of bringing different bars in actual contact during measurements, used only one bar calibrated on the metre and optical contact. Thus the metre became the unit of length for geodesy in the United States. 1983:). This territory was covered by a triangle network and included more than thirty observatories or stations whose position was determined astronomically. Bayer proposed to remeasure ten arcs of meridians and a larger number of arcs of parallels, to compare the curvature of the meridian arcs on the two slopes of the 2841:

states, on the contrary, that the mass of a body has an effect on all other bodies while modifying the structure of space. A massive body induces a curvature of the space around it in which the path of light is inflected, as was demonstrated by the displacement of the position of a star observed near

1817:

The definition of the length of a metre in the 1790s was founded upon Arc measurements in France and Peru with a definition that it was to be 1/40 millionth of the circumference of the earth measured through the poles. Such were the inaccuracies of that period that within a matter of just a few years

1452:

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 their curvature could be irregular. The distance from the North Pole to the Equator was then extrapolated from the

3016:

made directly against the international prototype metre; instead, the ratio of the wavelength of the krypton line to that of the cadmium line was determined in vacuum. This was then compared to the 1906 Fabry–Perot determination of the wavelength of the cadmium line in air (with a correction for the

253:

was one of the oldest known units of length. As the name suggests, before the invention of the metre during the French Revolution, many units of length were based on parts of the human body. The oldest known metal length standard corresponds to this Sumerian unit and dates from 2650 BCE. This copper

73:

in 1543. Increasingly accurate measurements were required, and scientists looked for measures that were universal and could be based on natural phenomena rather than royal decree or physical prototypes. Rather than the various complex systems of subdivision then in use, they also preferred a decimal

9048:

This aluminum bar, with an X-shaped cross-section, is a replica of the platinum international meter prototype housed in Paris and used as a standard for the metric system from 1889 to 1960. ... Like an actual meter standard, the bar is 102 centimeters long and there are marks 1 centimeter from each

6584:

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

5522:

4749:

Recueil d'observations géodésiques, astronomiques et physiques, exécutées par ordre du Bureau des longitudes de France, en Espagne, en France, en Angleterre et en Écosse, pour déterminer la variation de la pesanteur et des degrés terrestres sur le prolongement du Méridien de Paris, faisant suite au

2932:

The solution was to define the metre in the same manner as the angstrom had been defined in 1907, that is in terms of the best interferometric wavelength available. Advances in both experimental technique and theory showed that the cadmium line was actually a cluster of closely separated lines, and

2924:

By the 1950s, interferometry had become the method of choice for precise measurements of length, but there remained a practical problem imposed by the system of units used. The natural unit for expressing a length measured by interferometry was the ångström, but this result then had to be converted

2691:

The first (and only) follow-up comparison of the national standards with the international prototype was carried out between 1921 and 1936, and indicated that the definition of the metre was preserved to within 0.2 μm. At this time, it was decided that a more formal definition of the metre was

2481:

In the 1870s and in light of modern precision, a series of international conferences was held to devise new metric standards. When a conflict broke out regarding the presence of impurities in the metre-alloy of 1874, a member of the Preparatory Committee since 1870 and Spanish representative at the

5919:

Recueil d'observations géodésiques, astronomiques et physiques, exécutées par ordre du Bureau des longitudes de France en Espagne, en France, en Angleterre et en Écosse, pour déterminer la variation de la pesanteur et des degrés terrestres sur le prolongement du méridien de Paris... rédigé par MM.

2328:

until 1890. According to geodesists, these standards were secondary standards deduced from the Toise of Peru. In Europe, except Spain, surveyors continued to use measuring instruments calibrated on the Toise of Peru. Among these, the toise of Bessel and the apparatus of Borda were respectively the

930:

resurrected the idea of the seconds pendulum before the Constituent Assembly in 1790, suggesting that the new measure be defined at 45°N (a latitude that, in France, runs just north of Bordeaux and just south of Grenoble): despite the support of the Assembly, nothing came of Talleyrand's proposal.

313:

comprised 7500 Roman feet. The Romans imposed Roman units of measurement throughout their empire. During the Middle Ages, new feet of different lengths appeared in Europe. They all derived more or less directly from the Roman foot. These feet were divided into 12 inches, themselves divided into 12

2646:

For metrology the matter of expansibility was fundamental; as a matter of fact the temperature measuring error related to the length measurement in proportion to the expansibility of the standard and the constantly renewed efforts of metrologists to protect their measuring instruments against the

2445:

In 1867 at the second General Conference of the International Association of Geodesy held in Berlin, the question of an international standard unit of length was discussed in order to combine the measurements made in different countries to determine the size and shape of the Earth. According to a

2450:

the precedent year, the General Conference recommended the adoption of the metre in replacement of the toise of Bessel, the creation of an International Metre Commission, and the foundation of a World institute for the comparison of geodetic standards, the first step towards the creation of the

1958:

by means of gravimetric and leveling measurements, in order to deduce the exact knowledge of the terrestrial spheroid while taking into account local variations. To resolve this problem, it was necessary to carefully study considerable areas of land in all directions. Baeyer developed a plan to

8429:"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" 5727:"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" 3720:

At the time the second was defined as a fraction of the Earth's rotation time and determined by clocks whose precision was checked by astronomical observations. In 1936 French and German astronomers found that Earth rotation's speed is irregular. Since 1967 atomic clocks define the second. For

3199:

using any light source of known frequency, rather than defining a "preferred" source in advance. Given that there are more than 22,000 lines in the visible spectrum of iodine, any of which could be potentially used to stabilise a laser source, the advantages of flexibility are obvious.

3089: ≈ 3.39 μm). The krypton line was found to be asymmetrical, so different wavelengths could be found for the laser light depending on which point on the krypton line was taken for reference. The asymmetry also affected the precision to which the wavelengths could be measured. 1818:

more reliable measurements would have given a different value for the definition of this international standard. That does not invalidate the metre in any way but highlights the fact that continuing improvements in instrumentation made better measurements of the earth’s size possible.

2417:

standard had partially been destroyed in 1834, a new standard of reference was constructed using copies of the "Standard Yard, 1760", instead of the pendulum's length as provided for in the Weights and Measures Act of 1824, because the pendulum method proved unreliable. Nevertheless

1104:

would publish in 1821 their observations completing those of Delambre and Mechain. It was an account of the length's variation of the degrees of latitude along the Paris meridian as well as the account of the variation of the seconds pendulum's length along the same meridian between

2264:(IPM) and the arrangement of a system where national standards could be compared with it. The French government gave practical support to the creation of an International Metre Commission, which met in Paris in 1870 and again in 1872 with the participation of about thirty countries. 654:

composed of concentric layers of variable densities. Towards the end of the 18th century, the geodesists sought to reconcile the values of flattening drawn from the measurements of meridian arcs with that given by Clairaut's spheroid drawn from the measurement of gravity. In 1789,

2643:" (For all times, to all peoples); and this deed consisted in the approval and distribution, among the governments of the states supporting the Metre Convention, of prototype standards of hitherto unknown precision intended to propagate the metric unit throughout the whole world. 8754:"Bericht der schweizerischen Delegierten an der internationalen Meterkonferenz an den Bundespräsidenten und Vorsteher des Politischen Departements, J.J. Scherer in Erwin Bucher, Peter Stalder (ed.), Diplomatic Documents of Switzerland, vol. 3, doc. 66, dodis.ch/42045, Bern 1986" 2337:. These measuring devices consisted of bimetallic rulers in platinum and brass or iron and zinc fixed together at one extremity to assess the variations in length produced by any change in temperature. The combination of two bars made of two different metals allowed to take 8079:"Appareil construit pour les opérations au moyen desquelles on prolongera dans toute l'étendue de l'Espagne le réseau trigonométrique qui couvre la France in Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels" 5435:"Appareil construit pour les opérations au moyen desquelles on prolongera dans toute l'étendue de l'Espagne le réseau trigonométrique qui couvre la France in Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels" 3135:

Nevertheless, the infrared light from a methane-stabilised laser was inconvenient for use in practical interferometry. It was not until 1983 that the chain of frequency measurements reached the 633 nm line of the helium–neon laser, stabilised using molecular

2610:, delegate of Switzerland at this Diplomatic Conference in 1875, conformed to the opinion of Italy and Spain to create, in spite of French reluctance, the International Bureau of Weights and Measures in France as a permanent institution at the disadvantage of the 9360:"Détermination de la valeur en Ångströms de la longeur d'onde de la raie rouge du Cadmium considérée comme étalon primaire" [Determination of the value in Ångströms of the wavelength of the red line of cadmium under consideration as a primary standard]. 1802:'s model. 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 3977:

The term "prototype" does not imply that it was the first in a series and that other standard metres would come after it: the "prototype" metre was the one that came first in the logical chain of comparisons, that is the metre to which all other standards were

2520:, France. This new organisation was to construct and preserve a prototype metre bar, distribute national metric prototypes, and maintain comparisons between them and non-metric measurement standards. The organisation distributed such bars in 1889 at the first 1840:, Méchain had found that the difference between these latitudes was greater than predicted by direct measurement of distance by triangulation and that he did not dare to admit this inaccuracy. This was later explained by clearance in the central axis of the 2394:. If precision metrology had needed the help of geodesy, the latter could not continue to prosper without the help of metrology. It was then necessary to define a single unit to express all the measurements of terrestrial arcs and all determinations of the 1468:. 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. 3097:. Although visible and infrared frequencies were still too high to be directly measured, it was possible to construct a "chain" of laser frequencies that, by suitable multiplication, differ from each other by only a directly measurable frequency in the 1671:

in Paris. Ismail Mustafa had the task to carry out the experiments necessary for determining the expansion coefficients of the two platinum and brass bars, and to compare the Egyptian standard with a known standard. The Spanish standard designed by

2566:, Carlos Ibáñez e Ibáñez de Ibero had been elected president. His presidency was confirmed at the first meeting of the International Committee for Weights and Measures, on 19 April 1875. Three other members of the committee, the German astronomer, 1402:

A copy of the "provisional" metre installed 1796–1797, located in the wall of a building, 36 rue de Vaugirard, Paris. These metres were based on the "provisional" metre, because the expedition to re-determine the metre was not completed until

544:. Picard's geodetic observations had been confined to the determination of the magnitude of the earth considered as a sphere, but the discovery made by Jean Richer turned the attention of mathematicians to its deviation from a spherical form. 9704:

Pollock, C.R.; Jennings, D.A.; Petersen, F.R.; Wells, J.S.; Drullinger, R.E.; Beaty, E.C.; Evenson, K.M. (1983). "Direct frequency measurements of transitions at 520 THz (576 nm) in iodine and 260 THz (1.15 μm) in neon".

2636:

In 1889 the General Conference on Weights and Measures met at Sèvres, the seat of the International Bureau. It performed the first great deed dictated by the motto inscribed in the pediment of the splendid edifice that is the metric system:

955:

in the United Kingdom. More precisely, it was decided in 1824 that if the genuine standard of the yard was lost, it could be restored by reference to the length of a pendulum vibrating seconds at London. However, when the primary Imperial

1559:

and gravity in different points of the globe stimulated the creation of the first international scientific associations. The foundation of the Magnetischer Verein would be followed by that of the Central European Arc Measurement (German:

2316:, was the French primary standard of the toise, and the metre was officially defined by an artifact made of platinum kept in the National Archives. Besides the latter, another platinum and twelve iron standards of the metre were made by 6869:

Nouvelle détermination de la distance méridienne de Montjouy à Formentera, dévoilant l'inexactitude de celle dont il est fait mention dans la base du système métrique décimal, par M. Puissant,... lu à l'Académie des sciences, le 2 mai

940: 5766:

Clarke, Alexander Ross (1 January 1867). "X. Abstract of the results of the comparisons of the standards of length of England, France, Belgium, Prussia, Russia, India, Australia, made at the ordnance Survey Office, Southampton".

2937:

in natural cadmium (eight in total). To get the most precisely defined line, it was necessary to use a monoisotopic source and this source should contain an isotope with even numbers of protons and neutrons (so as to have zero

1684:'s double-toise N° 1, which served as a comparison module for the measurement of all geodesic bases in France, and was also to be compared to the Ibáñez apparatus. In 1954, the connection of the southerly extension of the 1778:. 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 175:

of the new prototypes of the metre and their comparison with each other and with the historical standard involved the development of specialized measuring equipment and the definition of a reproducible temperature scale.

2712:, this bar being subject to standard atmospheric pressure and supported on two cylinders of at least one centimetre diameter, symmetrically placed in the same horizontal plane at a distance of 571 mm from each other. 2229:, founded to combine the geodetic operations of different countries, in order to reach a new and more exact determination of the shape and dimensions of the Globe, prompted the project of reforming the foundations of the 925:

of 1789. France was particularly affected by the proliferation of length measures, and the need for reform was widely accepted across all political viewpoints, even if it needed the push of revolution to bring it about.

960:

standard was partially destroyed in 1834, a new standard of reference was constructed using copies of the "Standard Yard, 1760" instead of the pendulum's length as provided for in the Weights and Measures Act of 1824.

2377:

would mark the adoption of new scientific methods. It then became possible to accurately measure parallel arcs, since the difference in longitude between their ends could be determined thanks to the invention of the

1719:, through Great Britain, France and Spain to El Aghuat in Algeria, whose parameters were calculated from surveys carried out in the mid to late 19th century. It yielded a value for the equatorial radius of the earth 1463:

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

1177:, and took more than six years (1792–1798). The technical difficulties were not the only problems the surveyors had to face in the convulsed period of the aftermath of the Revolution: Méchain and Delambre, and later 1431:

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

1650:

an Observatory which he was keen to keep in harmony with the progress of this science still in progress. In 1858, a Technical Commission was set up to continue, by adopting the procedures instituted in Europe, the

3092:

Developments in electronics also made it possible for the first time to measure the frequency of light in or near the visible region of the spectrum, instead of inferring the frequency from the wavelength and the

2245:

decided, in order to make all the standards comparable, to propose to the Association to choose the metre for geodetic unit, and to create an international prototype metre differing as little as possible from the

3190:

The concept of defining a unit of length in terms of a time received some comment. In both cases, the practical issue is that time can be measured more accurately than length (one part in 10 for a second using a

2474:, whose theorem has long supported the assumption of an ellipsoid with three unequal axes for the figure of the Earth, inviting his French counterpart to undertake joint action to ensure the universal use of the 2368:

Historic Dutch replicas of metric standards in the collection of Rijksmuseum, Amsterdam: iron metre with case constructed by Étienne Lenoir in 1799, copper grave kilogram with case (1798), copper volume measures

6493:

Base du système métrique décimal, ou Mesure de l'arc du méridien compris entre les parallèles de Dunkerque et Barcelone. T. 1 /, exécutée en 1792 et années suivantes, par MM. Méchain et Delambre, rédigée par M.

5211:

7394:

Dictionnaire des inventions et découvertes anciennes et modernes, dans les sciences, les arts et l'industrie.... 2. H–Z / recueillis et mis en ordre par M. le marquis de Jouffroy; publié par l'abbé Migne,...

3617: 2692:

required (the 1889 decision had said merely that the "prototype, at the temperature of melting ice, shall henceforth represent the metric unit of length"), and this was agreed at the 7th CGPM in 1927.

9552:

Evenson, K.M.; Wells, J.S.; Petersen, F.R.; Danielson, B.L.; Day, G.W.; Barger, R.L.; Hall, J.L. (1972). "Speed of Light from Direct Frequency and Wavelength Measurements of the Methane-Stabilized Laser".

93:(a pendulum with a half-period of one second) one century earlier, but this was rejected as it had been discovered that this length varied from place to place with local gravity. A new unit of length, the 1723:= 6 377 935 metres, the ellipticity being assumed as 1/299.15. The radius of curvature of this arc is not uniform, being, in the mean, about 600 metres greater in the northern than in the southern part. 9341: 5370: 2650:

The construction of the international prototype metre and the copies which were the national standards was at the limits of the technology of the time. The bars were made of a special alloy, 90%

3070:, of which the first working version was constructed in the same year as the redefinition of the metre. Laser light is usually highly monochromatic, and is also coherent (all the light has the same 2724:

under its own weight. Because the prototype is a line standard, its full length is 102 cm, slightly longer than 1 metre. Cross-sectionally, it measures 16 mm × 16 mm.

179:

Progress in science finally allowed the definition of the metre to be dematerialized; thus in 1960 a new definition based on a specific number of wavelengths of light from a specific transition in

3512: 2744:

The comparison of the new prototypes of the metre with each other involved the development of special measuring equipment and the definition of a reproducible temperature scale. The BIPM's

1138:", a surveying instrument which allowed a much-improved precision in the measurement of angles between landmarks, but insisted that two different version of the device be calibrated one in 4327:"Article Pié, (Mesure de longueur.), vol. XII (1765), p. 562a–463 [563]b Enccre/ICE – Interface de Consultation de l'Édition numérique collaborative et critique de l'Encyclopédie" 3924: 6297:"X. Abstract of the results of the comparisons of the standards of length of England, France, Belgium, Prussia, Russia, India, Australia, made at the ordnance Survey Office, Southampton" 4352:"Article Mesure longue, (Antiq. Arts & Comm.), vol. X (1765), pp. 411b–418a Enccre/ICE – Interface de Consultation de l'Édition numérique collaborative et critique de l'Encyclopédie" 1109:

and the Baleares. Improvements in the measuring devices designed by Borda and used for this survey also raised hopes for a more accurate determination of the length of this meridian arc.

1185:, which he contracted while trying to improve his original results in northern Spain. In the meantime, the commission calculated a provisional value from older surveys of 443.44 3709: 3668: 7815: 5550: 522:

of 9.5 arcseconds, equivalent to an Earth–Sun distance of about 22,000 Earth radii. They were also the first astronomers to have access to an accurate and reliable value for the

3839: 5366:"Rapport de M. Faye sur un Mémoire de M. Peirce concernant la constance de la pesanteur à Paris et les corrections exigées par les anciennes déterminations de Borda et de Biot" 1738:, 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 3880: 9020: 7885:

Recherche des coefficients de dilatation et étalonnage de l'appareil à mesurer les bases géodésiques appartenant au gouvernement égyptien / par Ismaïl-Effendi-Moustapha, ...

7024:

Recherche des coefficients de dilatation et étalonnage de l'appareil à mesurer les bases géodésiques appartenant au gouvernement égyptien / par Ismaïl-Effendi-Moustapha, ...

1954:

Baeyer's goal was a new determination of anomalies in the shape of the Earth using precise triangulations, combined with gravity measurements. This involved determining the

4503:

Le système métrique des poids et mesures; son établissement et sa propagation graduelle, avec l'histoire des opérations qui ont servi à déterminer le mètre et le kilogramme

2752:, whose practically negligible coefficient of expansion made it possible to develop simpler baseline measurement methods, and for which its director, the Swiss physicist 9398: 3772: 453: 86: 8047: 6054:

Jean-Jacques Levallois, La méridienne de Dunkerque à Barcelone et la détermination du mètre (1792–1799), Vermessung, Photogrammetrie, Kulturtechnik, 89 (1991), 375–380.

8567:

Dodis, Diplomatische Dokumente der Schweiz | Documents diplomatiques suisses | Documenti diplomatici svizzeri | Diplomatic Documents of Switzerland | (30 March 1875),

5483:

Le général Ibáñez notice nécrologique lue au comité international des poids et mesures, le 12 septembre et dans la conférence géodésique de Florence, le 8 octobre 1891

854:

of 1875, when the metre was adopted as an international scientific unit of length for the convenience of continental European geodesists following forerunners such as

4064: 3547: 1286:

End of November 1798, Delambre and Méchain returned to Paris with their data, having completed the survey to meet a foreign commission composed of representatives of

9758:

Jennings, D.A.; Pollock, C.R.; Petersen, F.R.; Drullinger, R. E.; Evenson, K.M.; Wells, J.S.; Hall, J.L.; Layer, H.P. (1983). "Direct frequency measurement of the I

4209:"Du pied au mètredu marc au kiloL'histoire des unités des poids et mesuresévoquée par quelques objets emblématiques descollections du Musée d'histoire des sciences" 3124:

values for the speed of light, depending on which point on the krypton line was chosen to define the metre. This ambiguity was resolved in 1975, when the 15th

1508:

In 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

6928:"Über einen Fehler in der Berechnung der französischen Gradmessung und seineh Einfluß auf die Bestimmung der Figur der Erde. Von Herrn Geh. Rath und Ritter Bessel" 2494:

to rally France to the project to create an International Bureau of Weights and Measures equipped with the scientific means necessary to redefine the units of the

2598:

along with the Russian and Austrian representatives boycotted the Permanent Committee of the International Metre Commission in order to prompt the reunion of the

492:

meaning universal measure for this unit of length, but then it was discovered that the length of a seconds pendulum varies from place to place: French astronomer

8573:(in French), Diplomatische Dokumente der Schweiz | Documents diplomatiques suisses | Documenti diplomatici svizzeri | Diplomatic Documents of Switzerland | Dodis 1680:

was chosen for this purpose, as it had served as a model for the construction of the Egyptian standard. In addition, the Spanish standard had been compared with

9635:

Evenson, K.M.; Day, G. W.; Wells, J.S.; Mullen, L.O. (1972). "Extension of Absolute Frequency Measurements to the cw He☒Ne Laser at 88 THz (3.39 μ)".

8570:

Bericht der schweizerischen Delegierten an der internationalen Meterkonferenz an den Bundespräsidenten und Vorsteher des Politischen Departements, J. J. Scherer

2422:'s use of the metre and the creation of the Office of Standard Weights and Measures as an office within the Coast Survey contributed to the introduction of the 2029:

hesitated for a long time before giving in to the demands of the Association, which asked the French geodesists to take part in its work. It was only after the

6435:"Les origines du système métrique en France et la Convention du mètre de 1875, qui a ouvert la voie au Système international d'unités et à sa révision de 2018" 5574:"Les origines du système métrique en France et la Convention du mètre de 1875, qui a ouvert la voie au Système international d'unités et à sa révision de 2018" 2666:) to minimise the effects of torsional strain during length comparisons. The first castings proved unsatisfactory, and the job was given to the London firm of 6364:

Grand dictionnaire universel du XIXe siècle : français, historique, géographique, mythologique, bibliographique.... T. 11 MEMO-O / par M. Pierre Larousse

5497:"Histoire de l'appareil Ibañez-Brunner in Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels" 2925:

into metres using an experimental conversion factor – the wavelength of light used, but measured in metres rather than in ångströms. This added an additional

2896: 2696:

The unit of length is the metre, defined by the distance, at 0°, between the axes of the two central lines marked on the bar of platinum–iridium kept at the

7353:

Martina Schiavon. La geodesia y la investigación científica en la Francia del siglo XIX : la medida del arco de meridiano franco-argelino (1870–1895).

2426:

allowing the use of the metre in the United States, and preceded the choice of the metre as international scientific unit of length and the proposal by the

1013: 3066:(63.14 K, −210.01 °C) was the state-of-the-art light source for interferometry in 1960, but it was soon to be superseded by a new invention: the 9062: 2586:

representing Russia, and the Swiss geodesist of German origin, Adolphe Hirsch were also among the main architects of the Metre Convention. In the 1870s,

1786:, but which in detail differs from it so as to prohibit any generalization and any extrapolation from the measurement of a single meridian arc. In 1859, 4701: 3743: 2405:, might be so much damaged that comparison with it would be worthless, while Bessel had questioned the accuracy of copies of this standard belonging to 2284:

and given to the United States, which served as the standard for American cartography from 1890 replacing the Committee Meter, an authentic copy of the

735:

and the data of the meridian arc of Delambre and Méchain. This value was the result of a conjecture based on too limited data. Thus the results of the

9095: 4094: 2720:

of the prototype – the support points, separated by 0.5594 of the total length of the bar, that minimise shortening of the bar due to

6903:

Struve Geodetic Arc, 2006 International Conference, The Struve Arc and Extensions in Space and Time, Haparanda and Pajala, Sweden, 13–15 August 2006

5273:

Struve Geodetic Arc, 2006 International Conference, The Struve Arc and Extensions in Space and Time, Haparanda and Pajala, Sweden, 13–15 August 2006

4208: 4012: μm; taking the intensity-weighted mean point ("centre of gravity") of the krypton line as the standard, the wavelength of the methane line is 4448: 2559: 1583: 7817:

Bericht über die Verhandlungen der vom 30. September bis 7. October 1867 zu BERLIN abgehaltenen allgemeinen Conferenz der Europäischen Gradmessung

5552:

Bericht über die Verhandlungen der vom 30. September bis 7. October 1867 zu BERLIN abgehaltenen allgemeinen Conferenz der Europäischen Gradmessung

2627: 2441:

Creating the metre-alloy in 1874 at the Conservatoire des Arts et Métiers. Present Henri Tresca, George Matthey, Saint-Claire Deville, and Debray.

7898: 7868: 7439: 7408: 7037: 7007: 6884: 6852: 6508: 6265: 5934: 5226: 4452: 8869: 6801: 5693:[The measure of Paris] (in French). Laboratoire de Médiévistique Occidentale de Paris – via Sciences de l'Homme et de la Société. 2143: 1536: 4310: 2280:

Closeup of National Prototype Metre Bar No. 27, made in 1889 by the International Bureau of Weights and Measures (BIPM) in collaboration with

2011:

could open the field to scientific research of the highest interest, research that each State, taken in isolation, was not able to undertake.

1883:

with the aim of determining the shape and dimensions of the Earth. At the time of its creation, the association had sixteen member countries:

8960: 8651:

Torge, W. (1 April 2005). "The International Association of Geodesy 1862 to 1922: from a regional project to an international organization".

6613: 1092:, thus the French meridian arc, which would extend northwards across the United Kingdom, would also extend southwards to Barcelona, later to 2611: 9690: 8937: 8606: 7940:

Comptes-rendus des séances de la Commission permanente de l'Association géodésique internationale réunie à Florence du 8 au 17 octobre 1891

7181:

Comptes-rendus des séances de la Commission permanente de l'Association géodésique internationale réunie à Florence du 8 au 17 octobre 1891

6693: 2670:

who succeeded in producing thirty bars to the required specification. One of these, No. 6, was determined to be identical in length to the

2603: 2555: 2452: 2413:

Observatories, which he had compared to each other about 1840. This assertion was particularly worrying, because when the primary Imperial

7565:"From a Regional Project to an International Organization: The "Baeyer-Helmert-Era" of the International Association of Geodesy 1862–1916" 1667:

the study, in Europe, of the precision apparatus calibrated against the metre intended to measure the geodesic bases and already built by

1474: 9895: 8773:"Wilhelm Foerster's Role in the Metre Convention of 1875 and in the Early Years of the International Committee for Weights and Measures" 8516: 8143:

Discursos leidos ante la Real Academia de Ciencias Exactas Fisicas y Naturales en la recepcion pública de Don Joaquin Barraquer y Rovira

7702:"Wilhelm Foerster's Role in the Metre Convention of 1875 and in the Early Years of the International Committee for Weights and Measures" 7293:"Figure de la Terre, in Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers, par une Société de Gens de lettres" 5348:

Discursos leidos ante la Real Academia de Ciencias Exactas Fisicas y Naturales en la recepcion pública de Don Joaquin Barraquer y Rovira

5070: 4937: 3140:. That same year, the 17th CGPM adopted a definition of the metre, in terms of the 1975 conventional value for the speed of light: 2623:, just outside Paris. However, as an international organisation, the BIPM is under the ultimate control of a diplomatic conference, the 9686: 2563: 2521: 2206:

which was a prerequisit for both military operations and the creation of the infrastructures needed for industrial development such as

1759: 8547:"Carlos Ibáñez e Ibáñez de Ibero (14 avril 1825 – 29 janvier 1891), par Albert Pérard (inauguration d'un monument élevé à sa mémoire)" 5462:"Carlos Ibáñez e Ibáñez de Ibero (14 avril 1825 – 29 janvier 1891), par Albert Pérard (inauguration d'un monument élevé à sa mémoire)" 4165: 3553: 3195:

as opposed to four parts in 10 for the metre in 1983). The definition in terms of the speed of light also means that the metre can be

2487: 2242: 1751: 1673: 1571: 863: 7425:

Grandeur et figure de la terre / J.-B.-J. Delambre; ouvrage augmenté de notes, de cartes et publié par les soins de G. Bigourdan,...

6252:

Grandeur et figure de la terre / J.-B.-J. Delambre; ouvrage augmenté de notes, de cartes et publié par les soins de G. Bigourdan,...

1347: 927: 798:

Significant improvements in gravity measuring instruments must also be attributed to Bessel. He devised a gravimeter constructed by

897: 395: 9213: 3162:

The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum

2325: 2139: 1498: 327: 319: 1742:

was minimized in proportion to the length of the meridian arcs: the longer the meridian arcs, the more precise the image of the

1601:

declared to the French Academy of Sciences in 1836 that Jean Baptiste Joseph Delambre and Pierre Méchain had made errors in the

988: 2796: 2402: 1465: 1433: 756: 732: 587: 5298:"Ueber einen Fehler in der Berechnung der französischen Gradmessung und seinen Einfluss auf die Bestimmung der Figur der Erde" 2562:. At the session on 12 October 1872 of the Permanent Committee of the International Metre Commission, which was to become the 1547:, second). In 1836, he founded the Magnetischer Verein, the first international scientific association, in collaboration with 183:

allowed the standard to be universally available by measurement. In 1983 this was updated to a length defined in terms of the

9865: 9250: 8055: 7948: 7921: 7588: 7189: 6777: 6669: 6013: 5409: 5094: 5002: 1951:

created a Central Office, located at the Prussian Geodetic Institute, whose management was entrusted to Johann Jacob Baeyer.

1860:

also had an impact on accuracy of latitudes' determinations. Among all these sources of error, it was mainly an unfavourable

7997:

Recherches historiques sur les étalons de poids et mesures de l'observatoire et les appareils qui ont servi a les construire

7208: 6751:

in COMlTÉ INTERNATIONAL DES POIDS ET MESURES. PROCÈS-VERBAUX DES SÉANCES. DEUXIÈME SÉRIE. TOME II. SESSION DE 1903. pp. 5–7.

2075:

in 1898. The convention of the International Geodetic Association expired at the end of 1916. It was not renewed due to the

9039: 4072: 3409: 2591: 2427: 2374: 2255: 2226: 2022: 1948: 1755: 1562: 1262: 792: 391: 164: 8374: 2317: 1124: 4813: 3120:

almost 100 times lower than previous measurements in the microwave region. Or, somewhat inconveniently, the results gave

1810:

in the French meridian arc which determination had also been affected in a lesser proportion by systematic errors of the

1331: 1089: 885: 874: 368:

explaining the fall of bodies at the surface of the Earth. He also observed the regularity of the period of swing of the

68: 8863: 3473: 7334:

Société de physique et d'histoire naturelle de Genève.; Genève, Société de physique et d'histoire naturelle de (1861).

7317:

Société de physique et d'histoire naturelle de Genève.; Genève, Société de physique et d'histoire naturelle de (1859).

6233: 2838: 2346: 2151: 736: 591: 286: 267: 9389:

Hollberg, L.; Oates, C.W.; Wilpers, G.; Hoyt, C.W.; Barber, Z.W.; Diddams, S.A.; Oskay, W.H.; Bergquist, J.C. (2005).

2401:

In 1866, the most important concern was that the Toise of Peru, the standard of the toise constructed in 1735 for the

1245:. In an operation taking six weeks, the baseline was accurately measured using four platinum rods, each of length two 8954: 8462:"Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels" 8345: 7140:"Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels" 6993:

Notes biographiques de S. E. Mahmoud Pacha el Falaki (l'astronome), par Ismail-Bey Moustapha et le colonel Moktar-Bey

6208: 5632: 5242:"Comptes rendus hebdomadaires des séances de l'Académie des sciences / publiés... par MM. les secrétaires perpétuels" 4789: 4587: 4424: 4391: 222:

Where older traditional length measures are still used, they are now defined in terms of the metre – for example the

7854:

Notes biographiques de S.E. Mahmoud Pacha el Falaki (l'astronome), par Ismail-Bey Moustapha et le colonel Moktar-Bey

3077:

The shortcomings of the krypton standard were demonstrated by the measurement of the wavelength of the light from a

1068:. Instead of the seconds pendulum method, the commission of the French Academy of Sciences – whose members included 763:

would calculate the Earth's flattening from ten meridian arcs measured with sufficient accuracy using the method of

3988: 2837:, infinite and without boundaries and bodies gravitated around each other without changing the structure of space. 1315: 558:

length was a means to measure gravitational acceleration. In the 18th century, in addition to its significance for

8702: 8228: 5836: 1798:, using Schubert's data computed that the Earth ellipsoid could rather be a spheroid of revolution accordingly to 1605:, which had been used to determine the length of the metre. Errors in the method of calculating the length of the 1031: 144:, particularly in scientific usage, and it was officially established as an international measurement unit by the 9918: 9308:; Benoît, Jean-René (1895). "Détermination expérimentale de la valeur du mètre en longueurs d'ondes lumineuses". 7292: 7075:"A profile of General Carlos Ibáñez e Ibáñez de Ibero: first president of the International Geodetic Association" 6030: 4697: 4632: 2784: 1940: 1868:

and a metre "too short" compared to a more general definition taken from the average of a large number of arcs.

9066: 6405: 4530: 2080: 1339: 1335: 1045: 137: 6490:

Delambre, Jean-Baptiste (1749–1822) Auteur du texte; Méchain, Pierre (1744–1804) Auteur du texte (1806–1810).

5208:

Delambre, Jean-Baptiste (1749–1822) Auteur du texte; Méchain, Pierre (1744–1804) Auteur du texte (1806–1810).

4326: 1217: 659:

obtained by a calculation taking into account the measures of meridian arcs known at the time a flattening of

642:

synthesized the relationships existing between gravity and the shape of the Earth. Clairaut exposed there his

4712: 4351: 3673: 3624: 3246: 2534: 2350: 322:

each. Multiples of these feet became the length standards in various European cities. For example, the Paris

9103: 9022:

The International Bureau of Weights and Measures, 1875–1975 : translation of the BIPM centennial volume

4865: 4102: 2957:

both fulfil the condition of zero nuclear spin and have bright lines in the visible region of the spectrum.

2202:

would challenge Britain as the foremost industrial nation in Europe. This was accompanied by development in

1355: 554:

which explained variations of gravitational acceleration depending on latitude. He also discovered that the

8600: 2195: 2090: 1660: 1061: 893: 541: 263: 149: 3108:

Independent measurements of frequency and wavelength are, in effect, a measurement of the speed of light (

2929:

to any length result in metres, over and above the uncertainty of the actual interferometric measurement.

2753: 97:

was introduced – defined as one ten-millionth of the shortest distance from the North Pole to the equator

9858: 9590:

Barger, R.L.; Hall, J.L. (1973). "Wavelength of the 3.39-μm laser-saturated absorption line of methane".

8534:

National Institute of Standards and Technology 2003; Historical context of the SI: Unit of length (meter)

8155: 5365: 2459: 1359: 1208:

The project was split into two parts – the northern section of 742.7 km from the belfry, Dunkirk to

5891: 4008:

Taking the point of highest intensity as the reference wavelength, the methane line had a wavelength of

3323:

Platinum-iridium bar at melting point of ice, atmospheric pressure, supported by two rollers (7th CGPM)

2508:) of 1875 mandated the establishment of a permanent International Bureau of Weights and Measures (BIPM: 2194:

in 1871. Meanwhile most European countries had adopted the metre. The 1870s marked the beginning of the

2049:

was appointed member of the Permanent Commission which was presided by Carlos Ibáñez e Ibáñez de Ibero.

1379: 191:

The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the

9441: 3281: 3042: 2491: 2395: 1791: 1724: 373: 365: 2034: 8626: 8402: 5916:

Biot, Jean-Baptiste (1774–1862) Auteur du texte; Arago, François (1786–1853) Auteur du texte (1821).

2729: 2419: 2289: 1524: 1494: 1428: 1240: 993: 855: 575: 507: 407: 399: 238: 8837: 8510: 7099: 6911: 5711: 5281: 5268: 5064: 4931: 2594:

but its overwhelming influence was mitigated by that of neutral states. While the German astronomer

2214:, geodesists called for the creation of a "European international bureau for weights and measures". 1794:. He also proposed an ellipsoid with three unequal axes. In 1860, Elie Ritter, a mathematician from 638:('Theory of the Figure of the Earth, drawn from the Principles of Hydrostatics') published in 1743, 7273:, Allgemeine Deutsche Biographie (1. ed.), München/Leipzig: Duncker & Humblot, p. 231 3116:), and the results from the methane-stabilised laser gave the value for the speed of light with an 2658:, which was significantly harder than pure platinum, and have a special X-shaped cross section (a " 1664: 1663:

was in charge, in Egypt, of the direction of the work of the general map, the viceroy entrusted to

1555:. The coordination of the observation of geophysical phenomena such as the Earth's magnetic field, 1427:

and Jean-Baptiste Delambre calculated the distance from Dunkirk to Barcelona using the data of the

921:, little practical advance was made towards the establishment of the "universal measure" until the 827: 788: 192: 8941: 7367: 7264: 3000: wavelengths in vacuum of the radiation corresponding to the transition between the levels 2p 1017: 9637: 9592: 9555: 9336: 6146: 5580:. The new International System of Units / Le nouveau Système international d’unités (in French). 4265:

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences

4257: 4226: 3196: 3117: 2926: 2745: 2595: 2567: 2463: 2410: 1677: 656: 609: 582:

was the unit to which all celestial distances were to be referred. Indeed, Earth proved to be an

571: 8546: 7333: 7316: 6701: 6296: 6099: 5622: 5461: 2458:

Hassler's metrological and geodetic work also had a favourable response in Russia. In 1869, the

1112: 402:. They both also used a determination of the size of the Earth, then considered as a sphere, by 8182:"Über das preufs. Längenmaaß und die zu seiner Verbreitung durch Copien ergriffenen Maaßregeln" 7094: 6906: 5297: 5276: 4469:

The Elements of Commerce; or, a treatise on different calculations,-operations of exchange, etc

2918: 2757: 2269: 2211: 2191: 1787: 1548: 1420: 1295: 1174: 811: 9829: 9240: 8719: 8031: 7938: 7179: 4659: 4467: 3176:

when expressed in the unit m⋅s, where the second is defined in terms of the caesium frequency

3074:, unlike the light from a discharge lamp), both of which are advantageous for interferometry. 2312:

were the legal basis of units of length. A wrought iron ruler, the Toise of Peru, also called

208:

when expressed in the unit m⋅s, where the second is defined in terms of the caesium frequency

9889: 6169: 5698: 3517: 3082: 3038: 2868: 2354: 1920: 1799: 1681: 1639: 1424: 1371: 1351: 1120: 1073: 1069: 1065: 696: 643: 353: 58: 4895: 4747: 4558: 163:

and its copies such as the Committee Meter were replaced from 1889 at the initiative of the

158: 127: 9773: 9716: 9646: 9601: 9564: 9515: 9478: 9407: 9369: 9137: 8993: 8908: 8899: 8784: 8660: 8299: 8260: 8193: 7770: 7713: 7617: 7233:

Vermessung, Photogrammetrie, Kulturtechnik: VPK = Mensuration, Photogrammétrie, Génie Rural

7086: 6939: 6555: 6446: 5865: 5585: 5346: 5183: 4618: 4182: 3242: 3144:

The metre is the length of the path travelled by light in vacuum during a time interval of

2379: 2301: 2183: 2026: 1964: 1896: 1594: 1552: 1520: 1416: 1375: 1323: 1085: 1077: 859: 481: 124:

The historical French official standard of the metre was made available in the form of the

42: 6614:"A Tale About the First Weights and Measures Intercomparison in the United States in 1832" 1453:

measurement of the Paris meridian arc between Dunkirk and Barcelona and was determined as

951:

as a length standard did not die completely, and such a definition was used to define the

8: 9305: 7823:(in German). Berlin: Central-Bureau der Europäischen Gradmessung. 1868. pp. 123–134. 7564: 6769:

From artefacts to atoms : the BIPM and the search for ultimate measurement standards

6522:

American Philosophical Society.; Society, American Philosophical; Poupard, James (1825).

6379: 5949: 5810: 5558:(in German). Berlin: Central-Bureau der Europäischen Gradmessung. 1868. pp. 123–134. 4173: 2966: 2864: 2788: 2342: 2297: 2238: 2187: 2179: 2135: 2030: 1988: 1872: 1861: 1857: 1803: 1790:

demonstrated that several meridians had not the same length, confirming an hypothesis of

1747: 1739: 1685: 1567: 1367: 1258: 983: 819: 621: 133: 62: 9777: 9720: 9650: 9605: 9568: 9519: 9482: 9411: 9373: 9141: 8997: 8912: 8788: 8664: 8303: 8264: 8248: 8197: 8181: 7774: 7717: 7621: 7090: 6943: 6927: 6559: 6450: 5869: 5853: 5589: 5187: 5110: 4507: 4186: 9851: 9740: 9662: 9617: 9531: 9423: 9198: 9163: 8684: 8323: 7967: 7892: 7862: 7794: 7739: 7641: 7515: 7433: 7402: 7120: 7031: 7001: 6878: 6846: 6795: 6638: 6502: 6472: 6316: 6259: 6127: 5928: 5792: 5220: 5152: 4973: 4739: 4442: 3404: 3399: 3053: 2970: 2834: 2826: 2814: 2571: 2423: 2406: 2358: 2167: 2155: 2098: 2094: 1912: 1904: 1900: 1823:

Nomination of the STRUVE GEODETIC ARC for inscription on the WORLD HERITAGE LIST, p. 40

1635: 1307: 1303: 1299: 1097: 918: 881: 547: 7835: 7051: 6974: 6816: 5690: 5027: 2341:

into account without measuring the temperature. A French scientific instrument maker,

2051:

The International Geodetic Association gained global importance with the accession of

1049: 787:

would long be used by geodesists. An even more accurate value was proposed in 1901 by

9861: 9789: 9732: 9666: 9419: 9246: 9155: 9082:

Units of measurement: history, fundamentals and redefining the SI base units (2nd ed)

8950: 8802: 8688: 8676: 8327: 8315: 8268: 8209: 8001: 7944: 7917: 7798: 7786: 7758: 7743: 7731: 7645: 7633: 7584: 7507: 7476: 7185: 7124: 7112: 6955: 6783: 6773: 6723: 6675: 6665: 6643: 6563: 6476: 6464: 6441:. The new International System of Units / Le nouveau Système international d’unités. 6320: 6229: 6204: 6131: 6119: 6009: 5873: 5796: 5784: 5748: 5671: 5628: 5603: 5415: 5405: 5317: 5144: 5090: 5045: 5008: 4998: 4965: 4839: 4795: 4785: 4593: 4583: 4536: 4526: 4430: 4420: 4397: 4387: 4227:"Digital modeling of world's first known length reference unit: The Nippur cubit rod" 3445: 3101:

region. The frequency of the light from the methane-stabilised laser was found to be

2954: 2619:

In recognition of France's role in designing the metric system, the BIPM is based in

2583: 2471: 2467: 2338: 2309: 2111: 1992: 1916: 1656: 1638:

has ancient roots which were revived in the 19th century by the modernist impetus of

1575: 1513: 1343: 1327: 1319: 1287: 1276: 1014:

Earth's circumference § Historical use in the definition of units of measurement

922: 889: 551: 419: 342: 242: 78: 9744: 9427: 4743: 4127: 3250: 1178: 1170: 1101: 422:

and proposed this unit of measurement to be called the astronomical radius (French:

9781: 9724: 9654: 9621: 9609: 9572: 9535: 9523: 9506: 9486: 9447: 9415: 9194: 9167: 9145: 9001: 8916: 8820: 8792: 8668: 8440: 8307: 8201: 8117: 7778: 7721: 7672: 7625: 7576: 7466: 7240: 7104: 6947: 6633: 6625: 6590: 6454: 6308: 6111: 6073: 5776: 5738: 5661: 5624:

Full meridian of glory: perilous adventures in the competition to measure the Earth

5593: 5528: 5309: 5087:

From artefacts to atoms: the BIPM and the search for ultimate measurement standards

5035: 4238: 4190: 3752: 3018: 2599: 2551: 2501: 2483: 2131: 2127: 1924: 1841: 1811: 1716: 1475:

Metre § Early adoption of the metre as a scientific unit of length: the forerunners

1409: 1383: 1135: 1116: 1093: 1009: 948: 936: 869: 851: 807: 760: 620:, the study of variations in gravitational acceleration was a way to determine the 555: 415: 377: 168: 145: 90: 7883: 7533: 7455:"History of the International Polar Motion Service/International Latitude Service" 7392: 7229:"La méridienne de Dunkerque à Barcelone et la déterminiation du mètre (1972-1799)" 7052:"Nomination of the STRUVE GEODETIC ARC for inscription on the WORLD HERITAGE LIST" 7022: 6867: 6335: 6066:"La méridienne de Dunkerque à Barcelone et la déterminiation du mètre (1972–1799)" 5976: 5917: 5171: 4612: 2146:

in 1830. During the mid nineteenth century, following the defeat and expulsion of

1181:, were imprisoned several times during their surveys, and Méchain died in 1804 of 474:]), which had been recently renewed. He proposed a universal toise (French: 266:. Archaeologists consider that this 51.85 cm long unit was the origin of the 82: 9809:

Resolution 1, 17th Meeting of the General Conference on Weights and Measures

8106:"Exposé historique des travaux de la commission géodésique suisse de 1862 à 1892" 7852: 7661:"Exposé historique des travaux de la commission géodésique suisse de 1862 à 1892" 7423: 7335: 7318: 7266: 6991: 6523: 6491: 6362: 6250: 6174: 6003: 5209: 4501: 4242: 3918: 2780: 2667: 2281: 2175: 2115: 1884: 1743: 1735: 1711: 1610: 1602: 1291: 1209: 1201: 847: 784: 639: 629: 617: 172: 132:, a platinum bar held in Paris. During the mid nineteenth century, following the 9576: 6836: 5838:

The Statutes of the United Kingdom of Great Britain and Ireland [1827– ]

4284:

Des chiffres ou des lettres : compter, calculer, mesurer à l'époque romaine

2538:

as the distance between two lines on a standard bar composed of an alloy of 90%

1265:

in his 1744 survey of France. Méchain's baseline, of a similar length (6,006.25

650:

measured at different latitudes and the flattening of the Earth considered as a

518:

when Mars was at its closest to Earth in 1672. They arrived at a figure for the

9913: 9764: 9707: 9469: 8461: 8078: 7139: 6459: 6434: 5598: 5573: 5496: 5434: 5241: 5040: 4419:. Dupont-Bloch, Nicolas ( ed.). Louvain-la-Neuve: De Boeck. pp. 5–6. 4258:"Measurement and 3D modelling of an ancient measuring device: Nippur Cubit Rod" 3094: 2974: 2863:

measurements carried out using the international prototype metre were those of

2860: 2659: 2607: 2364: 2234: 2207: 2159: 2123: 2072: 2008: 1932: 1880: 1853: 1728: 1625: 1606: 1598: 1579: 1139: 1131: 911: 823: 519: 411: 346: 184: 98: 30: 9266: 8920: 8704:

Procès-verbaux: Commission Internationale du Mètre. Réunions générales de 1872

8672: 7782: 7471: 7454: 5012: 4866:"INRP – CLEA – Archives : Fascicule N° 137, Printemps 2012 Les distances" 2736: 1828: 1279:). Although Méchain's sector was half the length of Delambre, it included the 1212:

which was surveyed by Delambre and the southern section of 333.0 km from

818:

mathematician soon independently discovered a mathematical formula to correct

9907: 9884: 9834: 9328: 9159: 8873: 8806: 8680: 8493:

The creation of the International Bureau of Weights and Measures and its work

8319: 8272: 8213: 8205: 7790: 7735: 7637: 7511: 7480: 7116: 6959: 6951: 6787: 6567: 6521: 6468: 6226:

The Measure of all Things – The Seven-Year-Odyssey that Transformed the World

6201:

The Measure of all Things – The Seven-Year-Odyssey that Transformed the World

6123: 5877: 5788: 5752: 5675: 5607: 5340: 5321: 5313: 5148: 5049: 4969: 4941:. Vol. 08 (11th ed.). Cambridge University Press. pp. 801–813. 4926: 4799: 4597: 4540: 4434: 4401: 3992: 3940: 3926: 3896: 3882: 3855: 3841: 3192: 3071: 2892: 2872: 2808: 2717: 2587: 2575: 2495: 2475: 2230: 2199: 2119: 2068: 1509: 1486: 1081: 799: 764: 515: 310: 298: 8936: 8005: 6679: 5419: 2779:

In 1921, the Nobel Prize in Physics was awarded to another Swiss scientist,

2190:(1870–1871). Napoleonic Wars fostered German nationalism which later led to 2046: 1616: 9793: 9736: 9332: 8797: 8772: 8509: 8445: 8428: 7726: 7701: 7265:

Historische Commission bei der königl. Akademie der Wissenschaften (1908),

6647: 6595: 6312: 6149:. School of Mathematics and Statistics, University of St. Andrews, Scotland 6115: 5780: 5743: 5726: 5666: 5649: 5533: 5063: 4992: 4930: 3514:

The length of the pendulum is a function of the time lapse of half a cycle

3394: 3059: 3022: 2939: 2895:

as a secondary unit of length for spectroscopic measurements, first by the

2876: 2792: 2663: 2434:) to establish a "European international bureau for weights and measures". 2276: 1996: 1849: 1701: 1697: 1689: 1668: 1311: 1182: 1166: 1144: 1035: 595: 579: 537: 523: 279: 9390: 9242:

Measure of the Earth: The Enlightenment Expedition That Reshaped Our World

7228: 7108: 6767: 6065: 4523:

La science au péril de sa vie : les aventuriers de la mesure du monde

2851: 2748:

work led to the discovery of special alloys of iron–nickel, in particular

2590:

played a pivotal role in the unification of the metric system through the

2447: 1655:

work inaugurated under Muhammad Ali. This Commission suggested to Viceroy

715:. The Weights and Measures Commission would adopt in 1799 a flattening of 9362:

Transactions of the International Union for Cooperation in Solar Research

8717: 8012: 7995: 7757:

Drewes, Hermann; Kuglitsch, Franz; Adám, József; Rózsa, Szabolcs (2016).

7580: 7244: 6629: 6618:

Journal of Research of the National Institute of Standards and Technology

6077: 4891: 4816:[First determination of the distance from the Earth to the Sun]. 4554: 4379: 3722: 2800: 2252:

In 1867, the General Conference of the European Arc Measurement (German:

2203: 2171: 2076: 1944: 1928: 1908: 1629: 1590: 1363: 932: 803: 559: 527: 503: 493: 471: 447: 441: 403: 302: 290: 9899:. Vol. 18 (11th ed.). Cambridge University Press. p. 299. 9785: 9728: 9490: 9467:

Baird, K.M.; Howlett, L.E. (1963). "The International Length Standard".

8121: 7676: 7519: 7495: 7074: 5156: 4977: 4953: 4868:[NPRI – CLEA – Archives: Issue N ° 137, Spring 2012 Distances]. 3962: 3025:

to both the old prototype metre and the old definition of the angstrom.

1807: 1659:

the idea of buying geodetic devices which were ordered in France. While

1481: 635:

Théorie de la figure de la terre, tirée des principes de l'hydrostatique

9807: 9680: 7629: 7357:, 2004, Estudios sociales de la ciencia y la tecnologia, 23, pp. 11–30. 3338: 2978: 2884: 2769: 2387: 2004: 1767: 1620:

Ibáñez apparatus calibrated on the metric Spanish Standard and used at

1540: 1196: 1027: 676: 625: 605: 357: 337: 180: 102: 34: 21: 9658: 9613: 9005: 8311: 8105: 7660: 4194: 2903:(1927). Michelson's work in "measuring" the prototype metre to within 880:

In the 18th century, geodetic surveys found practical applications in

791:

according to gravity measurements performed under the auspices of the

9527: 9150: 9125: 8489:

La Création du Bureau International des Poids et Mesures et son Œuvre

7605: 5354:. Madrid: Imprenta de la Viuda e Hijo de D.E. Aguado. pp. 70–78. 3966: 3098: 2761: 2579: 2383: 2218: 2178:

of units of measurement respectively followed the successive fall of

2064: 2000: 1837: 1556: 1398: 1272: 1053: 1039: 944: 372:

and that this period depended on the length of the pendulum. In 1645

271: 259: 9888: 9182: 8740:

Procès-Verbaux des Séances. Deuxième Série. Tome II. Session de 1903

8737: 8288:"Charles Sanders Peirce and the first absolute measurement standard" 8287: 7337:

Memoires de la Société de physique et d'histoire naturelle de Genève

7320:

Memoires de la Société de physique et d'histoire naturelle de Genève

6543: 6167: 5892:"L'histoire des unités | Réseau National de la Métrologie Française" 5174:[The Royal Academy of Sciences and the Shape of the Earth]. 3461:

metres or about 150 million kilometres (93 million miles).

2620: 2517: 1836:

It was well known that by measuring the latitude of two stations in

1022: 9342:

Comptes rendus hebdomadaires des séances de l'Académie des sciences

9028:. U.S. Dept. of Commerce, National Bureau of Standards. p. 67. 7833: 6972: 5371:

Comptes rendus hebdomadaires des séances de l'Académie des sciences

3063: 3046: 2760:

in 1920. Guillaume's Nobel Prize marked the end of an era in which

2651: 2574:

and director of the German Weights and Measures Service, the Swiss

2539: 2163: 2147: 2018: 1976: 1865: 1783: 1771: 1715:

West Europe–Africa Meridian-arc: a meridian arc extending from the

1652: 1532: 1280: 1257:

being about 1.949 m). Thereafter he used, where possible, the

1106: 755:

would have been found, if they had been combined with those of the

651: 583: 381: 369: 234: 141: 4033:

for the maximum-intensity definition, with a relative uncertainty

1991:. Baeyer also planned to determine the curvature of the seas, the 1959:

coordinate geodetic surveys in the space between the parallels of

1060:

The question of measurement reform was placed in the hands of the

398:

and to the determination of the distance from Earth to the Sun by

9757: 8145:, Madrid, Imprenta de la Viuda e Hijo de D.E. Aguado, 1881, p. 78 6772:. Oxford. pp. 20, 37–38, 91–92, 70–72, 114–117, 144–147, 8. 5387: 5339:

This article incorporates text from this source, which is in the

4909: 4762: 4564: 3337:

1,650,763.73 wavelengths of light from a specified transition in

3078: 3033: 2950: 2946: 2934: 2880: 2855:

A Krypton-86 lamp used to define the metre between 1960 and 1983.

2804: 2773: 2765: 2721: 2655: 2543: 2391: 2330: 2222: 1968: 1960: 1892: 1888: 1876: 1763: 1705: 1621: 1502: 1271:), and also on a straight section of road between Vernet (in the 647: 567: 563: 511: 497: 361: 38: 9337:"Nouvelle détermination du Mètre en longueurs d'ondes lumieuses" 9310:

Travaux et Mémoires du Bureau International des Poids et Mesures

7184:(in French). De Gruyter, Incorporated. pp. 23–25, 100–109. 6528:. Vol. new ser.:v.2 (1825). Philadelphia pp. 234–278. 6171:

The metric versus the English system of weights and measures ...

6008:(in French). Springer Science & Business Media. p. 46. 4506:. University of Ottawa. Paris : Gauthier-Villars. pp. 3612:{\displaystyle \ell =g\left({\frac {T_{1/2}}{\pi }}\right)^{2}.} 2007:

in the north. In his mind, the cooperation of all the States of

1987:, in order to determine the influence of this mountain range on 1750:

measurement, it was resolved in the 1860s, at the initiative of

226:

has since 1959 officially been defined as exactly 0.9144 metre.

8230:

The Statutes of the United Kingdom of Great Britain and Ireland

8024: 7914:

Mesurer le monde: l'incroyable histoire de l'invention du mètre

5135:

Perrier, Général (1935). "Historique Sommaire de la Geodesie".

4696: 4661:

Centuries of Inventions: Encyclopedia and History of Inventions

4476: 3410:

Seconds pendulum § Relationship to the figure of the Earth

3137: 3128:

approved a conventional value of the speed of light as exactly

2334: 2056: 2042: 2038: 1980: 1936: 1845: 1795: 1775: 1643: 1528: 815: 566:

grew in importance as a means of empirically demonstrating the

480:) which was twice the length of the seconds pendulum. In 1675, 385: 255: 9060: 7534:"Polar motion | Earth's axis, wobble, precession | Britannica" 7391:

Jouffroy, Achille de (1785-1859) Auteur du texte (1852–1853).

5089:. New York & Oxford: Oxford University Press. p. 13. 5028:"Émilie Du Châtelet, un passeur scientifique au XVIIIe siècle" 2917: μm) was one of the reasons for which he was awarded the 2437: 1782:

is a ball, which on the whole can be assimilated to an oblate

9551: 9504:

Maiman, T.H. (1960). "Stimulated optical radiation in ruby".

7911: 7563:

Torge, Wolfgang (2016). Rizos, Chris; Willis, Pascal (eds.).

6664:. Encyclopedia Universalis. 1996. pp. 320, 370. Vol 10. 5404:. Encyclopedia Universalis. 1996. pp. 320, 370. Vol 10. 4814:"Première détermination de la distance de la Terre au Soleil" 4784:] (in French). Louvain-la-Neuve: De Boeck. pp. 5–6. 3790: 3762: 3067: 2969:

and lower operating temperatures for the lamp (which reduces

2830: 2749: 2345:, had made three direct copies of the Toise of Peru, one for 2324:

in the United States and served as standard of length in the

2305: 2060: 2052: 2014: 1955: 1779: 1693: 1647: 1232: 1213: 1188: 465: 433: 427: 323: 315: 282:

and 16 of these fingers gave a Roman foot of 29.633 cm.

275: 250: 89:. As a base unit of length, many scientists had favoured the 46: 26: 9703: 8000:(in French). Paris: Gauthier-Villars. pp. 7–8, 20, 32. 7882:

texte, Ismāʿīl-Afandī Muṣṭafá (1825–1901) Auteur du (1864).

7851:

texte, Ismāʿīl-Afandī Muṣṭafá (1825–1901) Auteur du (1886).

7422:

Delambre, Jean-Baptiste (1749–1822) Auteur du texte (1912).

7021:

texte, Ismāʿīl-Afandī Muṣṭafá (1825-1901) Auteur du (1864).

6990:

texte, Ismāʿīl-Afandī Muṣṭafá (1825–1901) Auteur du (1886).

6249:

Delambre, Jean-Baptiste (1749–1822) Auteur du texte (1912).

2373:

In the second half of the 19th century, the creation of the

2357:

also realized a copy of the Toise of Peru which was kept at

2217:

The intimate relationships that necessarily existed between

1200:

The north and south sections of the meridinal survey met at

9399:

Journal of Physics B: Atomic, Molecular and Optical Physics

8110:

Bulletin de la Société des Sciences Naturelles de Neuchâtel

7665:

Bulletin de la Société des Sciences Naturelles de Neuchâtel

7164:

J. M. López de Azcona, "Ibáñez e Ibáñez de Ibero, Carlos",

6654: 4133: 3835:

Distances measured using Google Earth. The coordinates are:

3302: 3125: 2989: 2900: 2822: 2818: 2462:

sent to the French Academy of Sciences a report drafted by

2414: 2353:

in 1821 and a third for Friedrich Bessel in 1823. In 1831,

1984: 1972: 1544: 957: 952: 907: 459: 331: 306: 294: 223: 9065:[History of the meter] (in French). Archived from 7989: 7987: 7209:"El General Ibáñez e Ibáñez de Ibero, Marqués de Mulhacén" 6342:(in French). pp. 262, 285, 288–290, 269, 276–277, 283 6098:

Martin, Jean-Pierre; McConnell, Anita (20 December 2008).

5648:

Martin, Jean-Pierre; McConnell, Anita (20 December 2008).

3995:

such that the wavelength (in air) of the cadmium line was

3021:

of air). In this way, the new definition of the metre was

3012:

The measurement of the wavelength of the krypton line was

2965:

Krypton is a gas at room temperature, allowing for easier

601: 8753: 8602:

The BIPM and the evolution of the definition of the metre

8568: 8433:

Philosophical Transactions of the Royal Society of London

7937:

commission, Internationale Erdmessung Permanente (1892).

7323:. Vol. 15. Geneve: Georg pp. 441–444, 484–485. 7178:

commission, Internationale Erdmessung Permanente (1892).

6301:

Philosophical Transactions of the Royal Society of London

5769:

Philosophical Transactions of the Royal Society of London

5731:

Philosophical Transactions of the Royal Society of London

5172:"L'Académie Royale des Sciences et la Figure de la Terre" 4414: 2093:

and Raoul Gautier (1854–1931), respectively directors of

9388: 8984:

Phelps, F. M. III (1966). "Airy Points of a Meter Bar".

8242: 8240: 7943:(in French). De Gruyter, Incorporated. pp. 99–107. 7756: 7453:

Yokoyama, Koichi; Manabe, Seiji; Sakai, Satoshi (2000).

7222: 7220: 7218: 5344: 4314:, vol. 11, Paris: Pierre Larousse, pp. 163–164 1574:

whose president, the Swiss meteorologist and physicist,

931:

This option, with one-third of this length defining the

822:

of this device which had been noticed by Plantamour and

9853:

Encyclopaedia of Scientific Units, Weights and Measures

9049:

end on this side to show the precise length of a meter.

8427:

Ross, Clarke Alexander; James, Henry (1 January 1873).

7984: 7349: 7347: 6838:

Histoire abrégée de l'astronomie / par Ernest Lebon,...

6295:

Clarke, Alexander Ross; James, Henry (1 January 1867).

5725:

Clarke, Alexander Ross; James, Henry (1 January 1873).

4582:(in French). Louvain-la-Neuve: De Boeck. pp. 5–6. 4166:"Foundations of the international system of units (SI)" 1609:

were taken into account by Bessel when he proposed his

1223:

Delambre used a baseline of about 10 km (6,075.90

982:

It has been suggested that portions of this section be

8520:. Vol. 8 (11th ed.). 1911. pp. 801–813. 7916:. Libres Champs. Paris: Flammarion. pp. 499–520. 6428: 6426: 5163: 5074:. Vol. 8 (11th ed.). 1911. pp. 801–813. 2977:), and so it was decided to select the orange line of 1848:

measurements contained significant systematic errors.

9634: 9040:"National Bureau of Standards Replica Meter Standard" 8339: 8337: 8237: 8036:. U.S. Government Printing Office. 1966. p. 529. 7215: 6144: 5394: 4286:(in French). Musée romain de Vallon. pp. 32, 43. 4087: 3676: 3627: 3556: 3520: 3476: 3359:

Length of the path travelled by light in a vacuum in

2985: ≈ 606 nm) as the new wavelength standard. 2897:

International Union for Cooperation in Solar Research

1864:

that gave an inaccurate determination of Barcelona's

1193:. This value was set by legislation on 7 April 1795. 846:

for the flattening of the Earth when he proposed his

414:. In 1671, Jean Picard also measured the length of a 81:(1789) came a desire to replace many features of the 9012: 8707:(in French). Imprim. Nation. 1872. pp. 153–155. 8504: 8502: 7695: 7693: 7558: 7556: 7554: 7344: 7068: 7066: 7064: 6830: 6828: 6579: 6577: 6537: 6535: 6489: 6290: 6288: 6286: 6284: 5207: 4633:"Science. 1791, l'adoption révolutionnaire du mètre" 4611:

Poynting, John Henry; Thompson, Joseph John (1907).

3203: 2704:

and declared Prototype of the metre by the 1st

2688:(1.6 μm short of the international prototype). 594:

and this new data called into question the value of

9032: 8529: 8527: 8070: 7487: 7452: 6896: 6894: 6761: 6759: 6757: 6742: 6423: 6371: 2891: ≈ 644 nm), led to the definition of the 1516:to assess temperature effects on the measurements. 814:and Isaac-Charles Élisée Cellérier (1818–1889), a 496:had measured the 0.3% difference in length between 9850: 8718:Comité des International Poids et Mesures (1876). 8538: 8334: 7912:Alder, Ken; Devillers-Argouarc'h, Martine (2015). 7810: 7808: 7203: 7201: 6835:Lebon, Ernest (1846–1922) Auteur du texte (1899). 6607: 6605: 6544:"Swiss Geodesy and the United States Coast Survey" 6525:Transactions of the American Philosophical Society 6433:Débarbat, Suzanne; Quinn, Terry (1 January 2019). 6100:"Joining the observatories of Paris and Greenwich" 5650:"Joining the observatories of Paris and Greenwich" 5572:Débarbat, Suzanne; Quinn, Terry (1 January 2019). 4281: 3703: 3662: 3611: 3541: 3507:{\displaystyle T=2\pi {\sqrt {\frac {\ell }{g}}}.} 3506: 3301:Platinum-iridium bar at melting point of ice (1st 2150:'s forces which brought an end to the short-lived 9443:Nobel Prize in Physics 1907 – Presentation Speech 8499: 8420: 7690: 7575:. Cham: Springer International Publishing: 3–18. 7571:. International Association of Geodesy Symposia. 7551: 7138:von Struve, Friedrich Georg Wilhelm (July 1857). 7061: 6825: 6574: 6532: 6281: 5240:von Struve, Friedrich Georg Wilhelm (July 1857). 4617:(4th ed.). London: Charles Griffin. p. 4324: 2086:Association Géodesique réduite entre États neutre 1754:who would become the first president of both the 1158:of a quarter-circle), with 100 minutes to a 699:meanwhile found at the same time a flattening of 9905: 9842: 9823: 9821: 9819: 9326: 9019:Page, Chester H.; Vigoureux, Paul, eds. (1975). 8524: 7340:. Vol. 16. Geneve: Georg pp. 165–196. 6891: 6815:Hassler, Harriet; Burroughs, Charles A. (2007). 6814: 6754: 4997:. Normandie roto impr.). Paris: Robert Laffont. 4775: 4610: 4577: 4255: 2564:International Committee for Weights and Measures 2560:International Committee for Weights and Measures 2105: 1584:International Committee for Weights and Measures 1501:. Trained in geodesy in Switzerland, France and 1204:, seen here dominating the Rodez skyline at left 900:. The unit of length used by the French was the 510:measured the parallax of Mars between Paris and 9304: 9291:Stephen Hawking, Paris, Dunod, 2003, 2014, 929 9267:"Lettres philosophiques/Lettre 15 - Wikisource" 8836:Guillaume, Charles-Édouard (11 December 1920). 7805: 7198: 6602: 6327: 6097: 6057: 5759: 5647: 5627:. New York; London: Copernicus Books/Springer. 4921: 4919: 4750:troisième volume de la Base du Système métrique 3058:The krypton-86 discharge lamp operating at the 2933:that this was due to the presence of different 2730:Metre § Metrology and paradigm shift in physics 1760:International Committee for Weights and Measure 8870:National Institute of Standards and Technology 8453: 7972:. International Bureau of Weights and Measures 7969:The International Metre Commission (1870–1872) 6354: 6145:O'Connor, J.J.; Robertson, E.F. (April 2003). 4520: 2992:in 1960 agreed a new definition of the metre: 2602:and to promote the foundation of a permanent 1056:, Spain – the southern end of the meridian arc 917:Despite scientific progresses in the field of 301:. A Roman cubit was equivalent to 1.5 feet, a 9816: 9018: 8397: 8395: 7837:Bulletin de la Société de géographie d'Égypte 7390: 6976:Bulletin de la Société de géographie d'Égypte 6926:Bessel, Friedrich Wilhelm (1 December 1841). 6866:Puissant, Louis (1769–1843) Auteur du texte. 6432: 6380:"Fixation de la longueur définitive du mètre" 6360: 6168:National Industrial Conference Board (1921). 5950:"Fixation de la longueur définitive du mètre" 5941: 5571: 4945: 910:, which became the geodetic unit used in the 526:, which had been measured by their colleague 486: 9691:International Bureau of Weights and Measures 9466: 9384: 9382: 9214:"Einstein, le révolutionnaire de la lumière" 8938:International Bureau of Weights and Measures 8619: 8607:International Bureau of Weights and Measures 8595: 8593: 8591: 8589: 8587: 8495:]. Paris: Gauthier-Villars. p. 321. 8156:"Metric Act of 1866 – US Metric Association" 7834:Jamʻīyah al-Jughrāfīyah al-Miṣrīyah (1876). 7168:, vol. VII, 1–2, Scribner's, New York, 1981. 6973:Jamʻīyah al-Jughrāfīyah al-Miṣrīyah (1876). 6901:Viik, T (2006). "F. W. Bessel and geodesy". 6091: 5426: 4916: 4495: 4493: 4491: 4447:: CS1 maint: multiple names: authors list ( 4282:Agustoni, Clara; Buchillier, Carmen (2018). 3821: 3814: 3806: 3798: 3788: 3780: 3770: 3760: 3750: 3741: 3735: 3272: 2706: 2698: 2672: 2638: 2625: 2604:International Bureau of Weights and Measures 2556:International Bureau of Weights and Measures 2526: 2510: 2453:International Bureau of Weights and Measures 2253: 2247: 2084: 1879:recommending international collaboration in 1734:Seventeen years after Bessel calculated his 1390: 1266: 1252: 1246: 1238: 1230: 1224: 1186: 943:shortly after gaining independence from the 901: 830:to determine a remarkably accurate value of 739:had been excluded, whereas a value close to 633: 531: 475: 463: 451: 439: 431: 376:was the first to determine the length of a " 156: 125: 9762:-stabilized He–Ne 473-THz (633-nm) laser". 9054: 8977: 8892: 8890: 7897:: CS1 maint: numeric names: authors list ( 7867:: CS1 maint: numeric names: authors list ( 7459:International Astronomical Union Colloquium 7438:: CS1 maint: numeric names: authors list ( 7407:: CS1 maint: numeric names: authors list ( 7036:: CS1 maint: numeric names: authors list ( 7006:: CS1 maint: numeric names: authors list ( 6883:: CS1 maint: numeric names: authors list ( 6851:: CS1 maint: numeric names: authors list ( 6507:: CS1 maint: numeric names: authors list ( 6294: 6264:: CS1 maint: numeric names: authors list ( 6194: 6192: 5933:: CS1 maint: numeric names: authors list ( 5724: 5545: 5543: 5515: 5453: 5225:: CS1 maint: numeric names: authors list ( 5056: 4776:Bond, Peter; Dupont-Bloch, Nicolas (2014). 4614:A Textbook of Physics: Properties of Matter 4578:Bond, Peter; Dupont-Bloch, Nicolas (2014). 4311:Grand dictionnaire universel du XIXe siècle 4122: 4120: 4065:"BIPM – Commission internationale du mètre" 4029:for the "centre-of-gravity" definition and 2554:was signed on 20 May 1875 in Paris and the 1597:of the Survey of the Coast, shortly before 1220:, Barcelona which was surveyed by Méchain. 540:used this measurement for establishing his 309:contained 1000 paces or 5000 feet. A Roman 66: 9848: 9687:General Conference on Weights and Measures 9589: 9187:Journal de Physique Théorique et Appliquée 9073: 8738:Comité Interational des Poids et Mesures. 8554:Institut de France – Académie des sciences 8392: 8180:Bessel, Friedrich Wilhelm (1 April 1840). 7936: 7840:. University of Michigan. . pp. 6–16. 7290: 7177: 7137: 6979:. University of Michigan. . pp. 6–16. 6800:: CS1 maint: location missing publisher ( 5968: 5469:Institut de France – Académie des sciences 5295: 5239: 4734: 4732: 4451:) CS1 maint: numeric names: authors list ( 4308:Larousse, Pierre, ed. (1874), "Métrique", 4297: 4295: 4293: 4224: 3428:The modern value of the solar parallax is 3028: 2846: 2633:(CGPM) rather than the French government. 2613:Conservatoire national des Arts et Métiers 2522:General Conference on Weights and Measures 1497:was appointed first Superintendent of the 1318:: Gabriel Císcar and Agustín de Pedrayes, 1229:) in length along a straight road between 1018:Meridian arc § History of measurement 9391:"Optical frequency/wavelength references" 9379: 9259: 9180: 9149: 8932: 8930: 8835: 8796: 8584: 8486: 8444: 8426: 8353:Bureau International des Poids et Mesures 8279: 8246: 8148: 8018: 7962: 7960: 7725: 7603: 7470: 7415: 7131: 7098: 6919: 6910: 6637: 6594: 6458: 6333: 5974: 5915: 5851: 5742: 5665: 5597: 5532: 5345:Ibáñez e Ibáñez de Ibero, Carlos (1881). 5280: 5170:Levallois, Jean-Jacques (May–June 1986). 5169: 5039: 4738: 4499: 4488: 4482: 2700:Bureau International des Poids et Mesures 2558:was created under the supervision of the 2512:Bureau International des Poids et Mesures 2320:in 1799. One of them became known as the 2304:, and unique artifacts made of different 2270:Metre § International prototype metre bar 1572:International Meteorological Organisation 1334:: Prospero Balbo, Antonio Vassali Eandi, 646:which established a relationship between 9883: 9238: 9183:"La mesure rapide des bases géodésiques" 8887: 8742:. Paris: Gauthier-Villars. pp. 5–7. 7421: 6821:. NIST Research Library. pp. 51–52. 6248: 6189: 6001: 5540: 5485:, Neuchâtel, imprimerie Attinger frères. 4990: 4925: 4307: 4159: 4157: 4155: 4153: 4151: 4149: 4147: 4145: 4143: 4117: 3032: 2850: 2735: 2708:Conférence Générale des Poids et Mesures 2628:Conférence générale des poids et mesures 2528:Conférence Générale des Poids et Mesures 2436: 2363: 2292:had brought to the United States in 1805 2275: 1827: 1762:, to remeasure the arc of meridian from 1710: 1615: 1531:to the basic units of the metre and the 1480: 1397: 1283:and hitherto unsurveyed parts of Spain. 1195: 1111: 1064:, who appointed a commission chaired by 1044: 1021: 964: 941:redefining the yard in the United States 898:Principal Triangulation of Great Britain 868: 600: 336: 233: 187:; this definition was reworded in 2019: 20: 16:Origins and values of the unit of length 9547: 9545: 8949:(8th ed.), pp. 142–143, 148, 8896: 8459: 8375:"BIPM – International Metre Commission" 8226: 8103: 8076: 7658: 7493: 7226: 6063: 5834: 5432: 5296:Rath, Geheimen; Ritter (January 1842). 5134: 5025: 4951: 4729: 4690: 4657: 4290: 4225:Duran, Zaide; Aydar, Umut (July 2012). 3704:{\displaystyle g={\ell \cdot \pi ^{2}}} 3663:{\displaystyle T_{1/2}=1\ \mathrm {s} } 3274: 2546:, measured at the melting point of ice. 2498:according to the progress of sciences. 2144:Office of Standard Weights and Measures 574:promoted in France in combination with 9906: 9827: 9503: 9181:Guillaume, C.-H.-Ed (1 January 1906). 8983: 8943:The International System of Units (SI) 8927: 8831: 8829: 8733: 8731: 8721:Procès-Verbaux des Séance de 1875–1876 8544: 8343: 8285: 8249:"Le Systeme Metrique est-il en Peril?" 8179: 7957: 7368:"c à Paris; vitesse de la lumière ..." 7271:Allgemeine Deutsche Biographie, Bd. 54 6925: 6589:, vol. 163, London, p. 463, 6583: 6541: 6104:Notes and Records of the Royal Society 6031:"How France created the metric system" 5854:"Le Systeme Metrique est-il en Peril?" 5765: 5718: 5688: 5654:Notes and Records of the Royal Society 5620: 5614: 5527:, vol. 163, London, p. 463, 5521: 5459: 4890: 4818:Les 350 ans de l'Observatoire de Paris 4563:(in French). pp. 3–4 – via 4553: 4465: 4163: 3728: 3158:This definition was reworded in 2019: 3054:Metre § Speed of light definition 2403:French Geodesic Mission to the Equator 1466:French Geodesic Mission to the Equator 757:French Geodetic Mission to the Equator 61:that is considered to have begun with 9079: 8770: 8724:. Paris: Gauthier-Villars. p. 3. 8650: 8566: 8286:Crease, Robert P. (1 December 2009). 7881: 7850: 7699: 7604:Levallois, J. J. (1 September 1980). 7562: 7428:pp. 202–203, 2015, 141–142, 178. 7072: 7020: 6989: 6834: 6818:Ferdinand Rudolph Hassler (1770–1843) 6765: 6223: 6198: 5567: 5565: 5084: 4378: 4374: 4372: 4140: 2158:an autonomous tributary state of the 1389: 986:out into another article titled 396:Newton's law of universal gravitation 171:bars kept across the globe. A better 9542: 9061:Direction générale des Entreprises. 8865:National Prototype Meter No. 27 7993: 7496:"Historique Sommaire De La Geodesie" 6900: 6865: 6611: 6228:. London: Abacus. pp. 240–241. 6203:. London: Abacus. pp. 227–230. 6161: 6002:Capderou, Michel (31 October 2011). 5884: 5494: 5266: 4954:"Historique Sommaire De La Geodesie" 4525:. Paris: Vuibert. pp. 124–125. 3209:Definitions of the metre since 1798 2640:A tous les temps, à tous les peuples 2460:Saint Petersburg Academy of Sciences 2260:) called for the creation of a new, 2227:International Association of Geodesy 2118:led to the adoption of the metre in 1941:United Kingdoms of Sweden and Norway 1688:with an arc running northwards from 989:Meridian arc of Delambre and Méchain 968: 229: 9239:Ferreiro, Larrie D. (31 May 2011). 8826: 8728: 8487:Guillaume, Charles-Édouard (1927). 6377: 5947: 5111:"Clairaut's equation | mathematics" 4782:The exploration of the solar system 4386:. Paris: Éd. du Seuil. p. 38. 4164:Nelson, Robert A. (December 1981). 2960: 2879:(1906), both using the red line of 2716:These support locations are at the 74:system to ease their calculations. 69:De revolutionibus orbium coelestium 13: 8838:"Nobel lecture: Invar and Elinvar" 8627:"A Note on the History of the IAG" 8403:"A Note on the History of the IAG" 7166:Dictionary of Scientific Biography 6278:The wall plaque next to the metre. 6028: 6005:Satellites : de Kepler au GPS 5562: 5128: 4415:Bond, Peter, (1948- ...). (2014). 4369: 3656: 2842:the Sun during an eclipse in 1919. 2600:Diplomatic Conference of the Metre 2375:International Geodetic Association 2347:Friedrich Georg Wilhelm von Struve 1844:causing wear and consequently the 1756:International Geodetic Association 1696:would bring the course of a major 1350:. The French commission comprised 1162:and 100 seconds to a minute. 1010:Metre § Meridional definition 850:. This was also the result of the 793:International Geodetic Association 737:French Geodetic Mission to Lapland 624:, whose crucial parameter was the 578:mathematical work and because the 165:International Geodetic Association 14: 9930: 9877: 8897:Barrell, H. (1962). "The Metre". 8247:Guillaume, Ed. (1 January 1916). 8141:Carlos Ibáñez e Ibáñez de Ibero, 6700:. 8 December 2015. Archived from 5852:Guillaume, Ed. (1 January 1916). 5026:Touzery, Mireille (3 July 2008). 4702:"Selected Astronomical Constants" 3204:History of definitions since 1798 2996:The metre is the length equal to 2833:. According to Newton, space was 2288:produced in 1799 in Paris, which 2079:. However, the activities of the 1875:sent a memorandum to the King of 392:Kepler's laws of planetary motion 9800: 9751: 9697: 9673: 9628: 9583: 9497: 9460: 9434: 9353: 9320: 9298: 9285: 9232: 9211: 9205: 9199:10.1051/jphystap:019060050024200 9174: 9118: 9088: 8966:from the original on 4 June 2021 8856: 8813: 8764: 8746: 8711: 8695: 8644: 8560: 8480: 8367: 8220: 8173: 8135: 8104:Zuerich, ETH-Bibliothek (1892). 8097: 8077:Brunner, Jean (1 January 1857). 8040: 7930: 7905: 7875: 7844: 7827: 7750: 7659:Zuerich, ETH-Bibliothek (1892). 7652: 7597: 7526: 7446: 7384: 7360: 7355:Revista Colombiana de Sociología 7327: 7310: 7284: 7258: 7227:Zuerich, ETH-Bibliothek (1991). 7171: 7158: 7044: 7014: 6983: 6966: 6859: 6612:Parr, Albert C. (1 April 2006). 6406:"Histoire du mètre | Métrologie" 6334:Levallois, Jean-Jacques (1986). 6064:Zuerich, ETH-Bibliothek (1991). 5975:Levallois, Jean-Jacques (1986). 5841:. H.M. statute and law printers. 5433:Brunner, Jean (1 January 1857). 5334: 5032:La revue pour l'histoire du CNRS 4778:L'exploration du système solaire 4658:Lucendo, Jorge (23 April 2020). 4580:L'exploration du système solaire 4417:L'exploration du système solaire 4301: 4025:The measured speed of light was 4019: 4002: 3989:International Astronomical Union 3981: 3971: 2883:. These results, which gave the 2728:This section is an excerpt from 2268:This section is an excerpt from 2152:French occupation of Lower Egypt 2142:in 1807 and the creation of the 1949:Central European Arc Measurement 1806:, in particular the latitude of 1473:This section is an excerpt from 1415:In 1799, a commission including 1408:This section is an excerpt from 973: 906:, while the English one was the 394:served both to the discovery of 148:of 1875 at the beginning of the 87:the traditional units of measure 9828:Wilkie, Tom (27 October 1983). 9245:. Basic Books. pp. 19–23. 9096:"BIPM – la définition du mètre" 8346:"Don Carlos Ibanez (1825–1891)" 8021:, pp. 8, 158–159, 176–177. 7759:"The Geodesist's Handbook 2016" 6808: 6716: 6686: 6515: 6483: 6398: 6272: 6242: 6217: 6138: 6048: 6022: 5995: 5909: 5845: 5828: 5803: 5682: 5641: 5495:Wolf, Rudolf (1 January 1891). 5488: 5475: 5358: 5328: 5289: 5260: 5233: 5201: 5103: 5078: 5019: 4984: 4884: 4858: 4832: 4806: 4769: 4709:The Astronomical Almanac Online 4698:United States Naval Observatory 4676: 4651: 4625: 4604: 4571: 4547: 4514: 4459: 4408: 4344: 4318: 4095:"BIPM – la définition du mètre" 3829: 3714: 3464: 3438: 3422: 2662:", named after French engineer 2488:Carlos Ibáñez e Ibáñez de Ibero 2329:main references for geodesy in 2138:prompted the foundation of the 1752:Carlos Ibáñez e Ibáñez de Ibero 1674:Carlos Ibáñez e Ibáñez de Ibero 1434:Spanish-French geodetic mission 1130:Borda was an avid supporter of 875:Anglo-French Survey (1784–1790) 864:Carlos Ibáñez e Ibáñez de Ibero 426:). He found the value of 440.5 140:, the metre gained adoption in 9136:(3397): 874. 1 December 1934. 8533: 8048:"Borda et le système métrique" 6410:metrologie.entreprises.gouv.fr 6361:Larousse, Pierre (1866–1877). 5983:(in French). pp. 288–290 4753:(in French). pp. 523, 529 4275: 4249: 4218: 4201: 4129:9th edition of the SI Brochure 4057: 3987:The IUSR (later to become the 2308:with distinct coefficients of 2081:International Latitude Service 1589:In 1834, Hassler, measured at 500:(in French Guiana) and Paris. 264:Istanbul Archaeological Museum 1: 9849:Cardarelli, François (2003). 9830:"Time to remeasure the metre" 9682:Resolution 2 of the 15th CGPM 8468:(in French). pp. 150–153 8085:(in French). pp. 150–153 7073:Soler, T. (1 February 1997). 6749:Heinrich VON WILD (1833–1902) 5503:(in French). pp. 370–371 5441:(in French). pp. 150–153 4500:Bigourdan, Guillaume (1901). 4051: 2740:Invar wire baseline apparatus 2535:International Prototype Metre 2446:preliminary proposal made in 2351:Heinrich Christian Schumacher 2262:international prototype metre 2106:International prototype metre 1563:Mitteleuropaïsche Gradmessung 1410:Metre § Meridional definition 1032:Church of Saint-Éloi, Dunkirk 896:Observatories and led to the 138:independence of Latin America 29:was one ten-millionth of the 8511:"Earth, Figure of the" 6585:length by Sir Henry James", 5523:length by Sir Henry James", 5065:"Earth, Figure of the" 4994:Les passions intellectuelles 4991:Badinter, Élisabeth (2018). 4932:"Earth, Figure of the" 4711:, p. K7, archived from 4664:. Jorge Lucendo. p. 246 4466:Dubost, Christopher (1818). 4243:10.1016/j.culher.2011.12.006 4231:Journal of Cultural Heritage 3748:, not to the later value in 3448:has been defined as exactly 3008:of the krypton 86 atom. 2839:Einstein's theory of gravity 1661:Mahmud Ahmad Hamdi al-Falaki 1570:in 1863, and by that of the 598:as Picard had calculated it. 586:through geodetic surveys in 542:law of universal gravitation 430:of the Toise of Châtelet (a 334:measured three London feet. 150:Second Industrial Revolution 7: 9859:Springer-Verlag London Ltd. 9838:(27 October 1983): 258–263. 9685:. 15th Meeting of the 9577:10.1103/PhysRevLett.29.1346 8986:American Journal of Physics 8054:(in French). Archived from 5896:metrologie-francaise.lne.fr 4356:enccre.academie-sciences.fr 4331:enccre.academie-sciences.fr 4256:Z. Duran; U. Aydar (2008). 3388: 2988:Accordingly, the 11th 2871:(1892–1893) and of Benoît, 2785:Michelson–Morley experiment 2382:. Furthermore, advances in 2154:, the metre was adopted in 2091:H.G. van de Sande Bakhuyzen 1975:and Trunz (German name for 1360:Charles-Augustin de Coulomb 25:An early definition of the 10: 9935: 9420:10.1088/0953-4075/38/9/003 7291:D'Alembert, Jean Le Rond. 6587:Philosophical Transactions 6460:10.1016/j.crhy.2018.12.002 5599:10.1016/j.crhy.2018.12.002 5525:Philosophical Transactions 5041:10.4000/histoire-cnrs.7752 4639:(in French). 25 March 2021 4031:299 792.4587(11) km s 4027:299 792.4562(11) km s 3051: 3043:Kastler-Brossel Laboratory 2803:'s pendulum experiment in 2727: 2492:French Academy of Sciences 2396:gravitational acceleration 2326:United States Coast Survey 2267: 2083:were continued through an 1512:at that time and measured 1472: 1407: 1165:The task of surveying the 1034:– the northern end of the 1007: 384:with a half-period of one 374:Giovanni Battista Riccioli 366:gravitational acceleration 8921:10.1080/00107516208217499 8771:Quinn, Terry (May 2019). 8673:10.1007/s00190-004-0423-0 8186:Astronomische Nachrichten 7783:10.1007/s00190-016-0948-z 7494:Perrier, Général (1935). 7472:10.1017/S0252921100061285 6932:Astronomische Nachrichten 5302:Astronomische Nachrichten 5269:"F.W. Bessel and Geodesy" 4952:Perrier, Général (1935). 2764:was leaving the field of 2754:Charles-Edouard Guillaume 2420:Ferdinand Rudolph Hassler 2390:have led to a new era of 2290:Ferdinand Rudolph Hassler 2089:thanks to the efforts of 1514:coefficients of expansion 1495:Ferdinand Rudolph Hassler 935:, was also considered by 888:, which aimed to connect 856:Ferdinand Rudolph Hassler 679:gave him a flattening of 508:Giovanni Domenico Cassini 400:Giovanni Domenico Cassini 341:The Meridian room of the 239:Giovanni Domenico Cassini 9084:. Springer. p. 108. 8344:Hirsch, Adolphe (1891). 8206:10.1002/asna.18400171302 8033:NIST Special Publication 6952:10.1002/asna.18420190702 6662:Encyclopedia Universalis 6542:Cajori, Florian (1921). 5402:Encyclopedia Universalis 5314:10.1002/asna.18420190702 5248:(in French). p. 509 5085:Quinn, Terry J. (2012). 4846:(in French). p. 234 3721:further information see 3415: 3369:of a second (17th CGPM) 2899:(1907) and later by the 2797:Descartes' Vortex theory 2592:European Arc Measurement 2478:in all scientific work. 2428:European Arc Measurement 2300:were defined by primary 2210:. During the process of 2196:Technological Revolution 2023:European Arc Measurement 1856:and later discovered by 1727:is depicted rather than 1665:Ismail Mustafa al-Falaki 1642:who founded in Sabtieh, 1603:meridian arc measurement 1527:and proposed adding the 1346:who had been invited by 828:Friedrich Robert Helmert 802:which was first used in 789:Friedrich Robert Helmert 761:Friedrich Wilhelm Bessel 193:speed of light in vacuum 33:, the distance from the 9896:Encyclopædia Britannica 9638:Applied Physics Letters 9593:Applied Physics Letters 9556:Physical Review Letters 9044:Smithsonian Institution 8545:Pérard, Albert (1957). 8517:Encyclopædia Britannica 8227:Britain, Great (1824). 7297:artflsrv04.uchicago.edu 7267:"Schubert, Theodor von" 7057:. pp. 40, 143–144. 6439:Comptes Rendus Physique 6147:"Jean Charles de Borda" 5835:Britain, Great (1824). 5689:Portet, Pierre (2011). 5578:Comptes Rendus Physique 5460:Pérard, Albert (1957). 5115:Encyclopedia Britannica 5071:Encyclopædia Britannica 4938:Encyclopædia Britannica 4900:(in French). p. 23 4521:Simaan, Arkan. (2001). 4325:Chevalier De Jaucourt. 4214:. June 2010. p. 2. 3542:{\displaystyle T_{1/2}} 3029:Speed of light standard 2973:of the line due to the 2927:measurement uncertainty 2847:Interferometric options 2817:changed conceptions of 2596:Wilhelm Julius Foerster 2568:Wilhelm Julius Foerster 2464:Otto Wilhelm von Struve 2432:Europäische Gradmessung 2386:combined with those of 2256:Europäische Gradmessung 2035:Charles-Eugène Delaunay 1971:) and the meridians of 1895:, seven German states ( 1792:Jean Le Rond d'Alembert 1678:Frutos Saavedra Meneses 1566:) on the initiative of 1134:: he had invented the " 657:Pierre-Simon de Laplace 610:Repsold-Bessel pendulum 349:is drawn on the ground. 345:(or Cassini room): the 9919:History of measurement 9368:: 18–34. 21 May 1907. 8798:10.1002/andp.201800355 8460:Brunner, Jean (1857). 8446:10.1098/rstl.1873.0014 8052:Association Mesure Lab 7727:10.1002/andp.201800355 6596:10.1098/rstl.1873.0014 6548:The Scientific Monthly 6313:10.1098/rstl.1867.0010 6116:10.1098/rsnr.2008.0029 6072:(in French): 377–378. 5811:"The seconds pendulum" 5781:10.1098/rstl.1867.0010 5744:10.1098/rstl.1873.0014 5706:Cite journal requires 5667:10.1098/rsnr.2008.0029 5534:10.1098/rstl.1873.0014 4485:, pp. 8, 158–159. 3822: 3815: 3807: 3799: 3789: 3781: 3771: 3761: 3751: 3742: 3736: 3705: 3664: 3613: 3543: 3508: 3273: 3241:part of one half of a 3049: 3010: 2919:Nobel Prize in Physics 2856: 2758:Nobel Prize in Physics 2741: 2714: 2707: 2699: 2673: 2639: 2626: 2527: 2511: 2442: 2398:by means of pendulum. 2370: 2293: 2254: 2248: 2212:unification of Germany 2192:unification of Germany 2085: 1833: 1826: 1788:Friedrich von Schubert 1770:and to extend it from 1736:ellipsoid of reference 1732: 1632: 1549:Alexander von Humboldt 1525:Earth's magnetic field 1490: 1421:Jean Henri van Swinden 1404: 1391: 1296:Jean Henri van Swinden 1275:area) and Salces (now 1267: 1253: 1247: 1239: 1231: 1225: 1205: 1187: 1175:Jean-Baptiste Delambre 1127: 1057: 1042: 902: 877: 848:ellipsoid of reference 812:Charles Sanders Peirce 640:Alexis Claude Clairaut 634: 613: 532: 487: 476: 464: 452: 440: 432: 350: 258:, on the banks of the 254:bar was discovered in 246: 157: 126: 67: 50: 9890:"Metric System" 9126:"Dr. C. E. Guillaume" 7700:Quinn, Terry (2019). 7109:10.1007/s001900050086 6766:Quinn, T. J. (2012). 6336:"La Vie des sciences" 5977:"La Vie des sciences" 5621:Murdin, Paul (2009). 4840:"1967LAstr..81..234G" 3706: 3665: 3614: 3544: 3509: 3036: 2994: 2887:of the cadmium line ( 2854: 2739: 2694: 2440: 2367: 2355:Henri-Prudence Gambey 2279: 1921:Saxe-Coburg and Gotha 1831: 1815: 1800:Adrien-Marie Legendre 1714: 1619: 1553:Wilhelm Edouard Weber 1484: 1425:Adrien-Marie Legendre 1401: 1382:, Pierre Méchain and 1380:Louis Lefèvre-Ginneau 1376:Pierre- Simon Laplace 1372:Joseph-Louis Lagrange 1352:Jean-Charles de Borda 1199: 1121:Jean-Charles de Borda 1115: 1066:Jean-Charles de Borda 1048: 1025: 965:Meridional definition 873:Triangulation of the 872: 767:and found a value of 697:Adrien-Marie Legendre 632:. In his famous work 604: 530:in 1669 as 3,269,000 354:Scientific revolution 340: 262:, and is kept in the 237: 99:passing through Paris 59:Scientific Revolution 24: 9080:Gupta, S.V. (2020). 8900:Contemporary Physics 8876:on 16 September 2008 7581:10.1007/1345_2015_42 7371:expositions.obspm.fr 7245:10.5169/seals-234595 6630:10.6028/jres.111.003 6078:10.5169/seals-234595 5691:"La mesure de Paris" 5197:– via Gallica. 3941:41.36333°N 2.16694°E 3897:44.43250°N 2.57333°E 3856:51.03556°N 2.37611°E 3740:are referred to the 3674: 3625: 3554: 3518: 3474: 3214:Basis of definition 3130:299 792 458 m s 2945:Several isotopes of 2532:), establishing the 2490:intervened with the 2380:electrical telegraph 2298:units of measurement 2184:Second French Empire 1897:Grand Duchy of Baden 1804:vertical deflections 1740:vertical deflections 1657:Mohammed Sa'id Pasha 1521:Carl Friedrich Gauss 1338:: Pietro Franchini, 1330:: Ambrogio Multedo, 1324:Johann Georg Tralles 1259:triangulation points 860:Carl Friedrich Gauss 482:Tito Livio Burattini 330:, while the English 101:, assuming an Earth 55:history of the metre 9786:10.1364/OL.8.000136 9778:1983OptL....8..136J 9729:10.1364/OL.8.000133 9721:1983OptL....8..133P 9651:1972ApPhL..20..133E 9606:1973ApPhL..22..196B 9569:1972PhRvL..29.1346E 9520:1960Natur.187..493M 9491:10.1364/AO.2.000455 9483:1963ApOpt...2..455B 9412:2005JPhB...38S.469H 9374:1908TIUCS...2...17. 9327:Benoît, Jean-René; 9142:1934Natur.134R.874. 9063:"Histoire du mètre" 8998:1966AmJPh..34..419P 8913:1962ConPh...3..415B 8789:2019AnP...53100355Q 8665:2005JGeod..78..558T 8304:2009PhT....62l..39C 8265:1916LAstr..30..242G 8198:1840AN.....17..193B 8122:10.5169/seals-88335 7994:Wolf, M. C (1882). 7775:2016JGeod..90..907D 7718:2019AnP...53100355Q 7677:10.5169/seals-88335 7622:1980BGeod..54..248L 7610:Bulletin géodésique 7606:"Notice historique" 7506:: 117–129, p. 128. 7146:. pp. 509, 510 7091:1997JGeod..71..176S 6944:1841AN.....19...97B 6704:on 18 December 2023 6560:1921SciMo..13..117C 6497:pp. 93–94, 10. 6451:2019CRPhy..20....6D 6378:Suzanne, Débarbat. 6224:Alder, Ken (2002). 6199:Alder, Ken (2002). 5948:Suzanne, Débarbat. 5870:1916LAstr..30..242G 5590:2019CRPhy..20....6D 5188:1986CRASG...3..261L 5176:La Vie des Sciences 4740:Biot, Jean-Baptiste 4187:1981PhTea..19..596N 4174:The Physics Teacher 4136:, 2019, p. 131 4075:on 18 November 2018 3952:Montjuïc, Barcelona 3936: / 3892: / 3851: / 3210: 2967:isotopic enrichment 2865:Albert A. Michelson 2789:luminiferous aether 2787:had questioned the 2516:) to be located in 2506:Convention du Mètre 2343:Jean Nicolas Fortin 2314:Toise de l'Académie 2249:mètre des Archives. 2188:Franco-Prussian War 2180:First French Empire 2140:Survey of the Coast 2136:American Revolution 2041:at the Congress of 2031:Franco-Prussian War 1989:vertical deflection 1965:Freetown Christiana 1873:Johann Jacob Baeyer 1862:vertical deflection 1858:Seth Carlo Chandler 1832:Struve Geodetic Arc 1748:Struve Geodetic Arc 1700:back to land where 1686:Struve Geodetic Arc 1611:reference ellipsoid 1568:Johann Jacob Baeyer 1535:in the form of the 1499:Survey of the Coast 1485:Triangulation near 1417:Johan Georg Tralles 1332:Kingdom of Sardinia 1123:and constructed by 1090:Anglo-French Survey 1062:Academy of Sciences 886:Anglo-French Survey 826:. This would allow 785:reference ellipsoid 622:figure of the Earth 580:radius of the Earth 484:suggested the term 289:was divided into 4 134:American Revolution 63:Nicolaus Copernicus 41:, measured along a 8777:Annalen der Physik 8653:Journal of Geodesy 7763:Journal of Geodesy 7706:Annalen der Physik 7630:10.1007/BF02521470 7538:www.britannica.com 7079:Journal of Geodesy 6905:. pp. 10, 6. 5275:. pp. 6, 10. 5034:(in French) (21). 4897:Mesure de la terre 4844:adsbit.harvard.edu 4560:Mesure de la terre 3701: 3660: 3609: 3539: 3504: 3405:History of geodesy 3400:Length measurement 3275:Mètre des Archives 3208: 3103:88.376 181 627(50) 3050: 2857: 2827:general relativity 2815:special relativity 2756:, was granted the 2742: 2674:mètre des Archives 2572:Berlin Observatory 2570:, director of the 2443: 2424:Metric Act of 1866 2371: 2359:Altona Observatory 2294: 2286:Mètre des Archives 2198:a period in which 2168:continental Europe 2156:Khedivate of Egypt 2148:Napoleon Bonaparte 2099:Geneva Observatory 2095:Leiden Observatory 2045:in 1871. In 1874, 1999:in the south, the 1913:Kingdom of Prussia 1905:Kingdom of Hanover 1901:Kingdom of Bavaria 1889:Kingdom of Belgium 1871:As early as 1861, 1834: 1733: 1725:Greenwich meridian 1636:Egyptian astronomy 1633: 1491: 1405: 1392:Mètre des Archives 1308:Kingdom of Denmark 1304:Lorenzo Mascheroni 1300:Cisalpine Republic 1206: 1128: 1098:Jean-Baptiste Biot 1058: 1043: 947:. The idea of the 882:French cartography 878: 614: 572:Émilie du Châtelet 548:Christiaan Huygens 424:Rayon Astronomique 351: 247: 159:Mètre des Archives 128:Mètre des Archives 65:'s publication of 51: 9867:978-1-4471-1122-1 9659:10.1063/1.1654077 9614:10.1063/1.1654608 9563:(19): 1346–1349. 9514:(4736): 493–494. 9271:fr.wikisource.org 9252:978-0-465-02345-5 9212:Huet, Sylvestre. 9006:10.1119/1.1973011 8556:. pp. 26–28. 8312:10.1063/1.3273015 8058:on 29 August 2023 7950:978-3-11-128691-4 7923:978-2-08-130761-2 7857:. pp. 10–11. 7590:978-3-319-30895-1 7191:978-3-11-128691-4 6996:. pp. 10–11. 6841:pp. 168–171. 6779:978-0-19-990991-9 6671:978-2-85229-290-1 6650:– via NIST. 6015:978-2-287-99049-6 5923:pp. viii–ix. 5920:Biot et Arago,... 5815:www.roma1.infn.it 5471:. pp. 26–28. 5411:978-2-85229-290-1 5378:: 1463–1466. 1880 5096:978-0-19-530786-3 5004:978-2-221-20345-3 4684:Misura Universale 4384:Le mètre du monde 4195:10.1119/1.2340901 4014:3.392 231 376(12) 4010:3.392 231 404(12) 3946:41.36333; 2.16694 3902:44.43250; 2.57333 3876:– Belfry, Dunkirk 3861:51.03556; 2.37611 3654: 3594: 3499: 3498: 3446:astronomical unit 3386: 3385: 3245:, measurement by 3083:helium–neon laser 3039:helium–neon laser 2913:of a wavelength ( 2791:in 1905, just as 2584:Heinrich von Wild 2472:Moritz von Jacobi 2468:Heinrich von Wild 2339:thermal expansion 2225:explain that the 2112:French Revolution 1993:Mediterranean Sea 1917:Kingdom of Saxony 1576:Heinrich von Wild 1344:Giovanni Fabbroni 1328:Ligurian Republic 1320:Helvetic Republic 1288:Batavian Republic 1277:Salses-le-Chateau 1218:Montjuïc Fortress 1038:running south to 1006: 1005: 1001: 923:French Revolution 820:systematic errors 731:by combining the 568:theory of gravity 552:centrifugal force 477:toise universelle 420:Paris Observatory 343:Paris Observatory 245:in the background 243:Paris Observatory 230:Universal measure 79:French Revolution 9926: 9900: 9892: 9872: 9871: 9856: 9846: 9840: 9839: 9825: 9814: 9813: 9804: 9798: 9797: 9755: 9749: 9748: 9701: 9695: 9694: 9677: 9671: 9670: 9632: 9626: 9625: 9587: 9581: 9580: 9549: 9540: 9539: 9528:10.1038/187493a0 9501: 9495: 9494: 9464: 9458: 9457: 9456: 9454: 9448:Nobel Foundation 9438: 9432: 9431: 9406:(9): S469–S495. 9395: 9386: 9377: 9376: 9357: 9351: 9350: 9324: 9318: 9317: 9302: 9296: 9294: 9289: 9283: 9282: 9280: 9278: 9263: 9257: 9256: 9236: 9230: 9229: 9227: 9225: 9209: 9203: 9202: 9178: 9172: 9171: 9153: 9151:10.1038/134874b0 9122: 9116: 9115: 9113: 9111: 9106:on 30 April 2017 9102:. Archived from 9092: 9086: 9085: 9077: 9071: 9070: 9058: 9052: 9051: 9036: 9030: 9029: 9027: 9016: 9010: 9009: 8981: 8975: 8974: 8973: 8971: 8965: 8948: 8934: 8925: 8924: 8894: 8885: 8884: 8883: 8881: 8872:, archived from 8860: 8854: 8853: 8851: 8849: 8833: 8824: 8821:Metre Convention 8817: 8811: 8810: 8800: 8768: 8762: 8761: 8760:. 30 March 1875. 8750: 8744: 8743: 8735: 8726: 8725: 8715: 8709: 8708: 8699: 8693: 8692: 8648: 8642: 8641: 8639: 8637: 8623: 8617: 8616: 8615: 8613: 8597: 8582: 8581: 8580: 8578: 8564: 8558: 8557: 8551: 8542: 8536: 8531: 8522: 8521: 8513: 8506: 8497: 8496: 8484: 8478: 8477: 8475: 8473: 8457: 8451: 8450: 8448: 8424: 8418: 8417: 8415: 8413: 8399: 8390: 8389: 8387: 8385: 8371: 8365: 8364: 8362: 8360: 8350: 8341: 8332: 8331: 8283: 8277: 8276: 8244: 8235: 8234: 8224: 8218: 8217: 8177: 8171: 8170: 8168: 8166: 8152: 8146: 8139: 8133: 8132: 8130: 8128: 8101: 8095: 8094: 8092: 8090: 8074: 8068: 8067: 8065: 8063: 8044: 8038: 8037: 8028: 8022: 8016: 8010: 8009: 7991: 7982: 7981: 7979: 7977: 7964: 7955: 7954: 7934: 7928: 7927: 7909: 7903: 7902: 7896: 7888: 7879: 7873: 7872: 7866: 7858: 7848: 7842: 7841: 7831: 7825: 7824: 7822: 7812: 7803: 7802: 7754: 7748: 7747: 7729: 7697: 7688: 7687: 7685: 7683: 7656: 7650: 7649: 7601: 7595: 7594: 7560: 7549: 7548: 7546: 7544: 7530: 7524: 7523: 7491: 7485: 7484: 7474: 7450: 7444: 7443: 7437: 7429: 7419: 7413: 7412: 7406: 7398: 7388: 7382: 7381: 7379: 7377: 7364: 7358: 7351: 7342: 7341: 7331: 7325: 7324: 7314: 7308: 7307: 7305: 7303: 7288: 7282: 7281: 7280: 7278: 7262: 7256: 7255: 7253: 7251: 7224: 7213: 7212: 7205: 7196: 7195: 7175: 7169: 7162: 7156: 7155: 7153: 7151: 7135: 7129: 7128: 7102: 7070: 7059: 7058: 7056: 7048: 7042: 7041: 7035: 7027: 7018: 7012: 7011: 7005: 6997: 6987: 6981: 6980: 6970: 6964: 6963: 6923: 6917: 6916: 6914: 6898: 6889: 6888: 6882: 6874: 6863: 6857: 6856: 6850: 6842: 6832: 6823: 6822: 6812: 6806: 6805: 6799: 6791: 6763: 6752: 6746: 6740: 6739: 6737: 6735: 6724:"Wild, Heinrich" 6720: 6714: 6713: 6711: 6709: 6694:"History of IMO" 6690: 6684: 6683: 6658: 6652: 6651: 6641: 6624:(1): 31–32, 36. 6609: 6600: 6599: 6598: 6581: 6572: 6571: 6539: 6530: 6529: 6519: 6513: 6512: 6506: 6498: 6487: 6481: 6480: 6462: 6430: 6421: 6420: 6418: 6416: 6402: 6396: 6395: 6393: 6391: 6375: 6369: 6368: 6358: 6352: 6351: 6349: 6347: 6331: 6325: 6324: 6292: 6279: 6276: 6270: 6269: 6263: 6255: 6246: 6240: 6239: 6221: 6215: 6214: 6196: 6187: 6186: 6184: 6182: 6165: 6159: 6158: 6156: 6154: 6142: 6136: 6135: 6095: 6089: 6088: 6086: 6084: 6061: 6055: 6052: 6046: 6045: 6043: 6041: 6029:Ramani, Madhvi. 6026: 6020: 6019: 5999: 5993: 5992: 5990: 5988: 5972: 5966: 5965: 5963: 5961: 5945: 5939: 5938: 5932: 5924: 5913: 5907: 5906: 5904: 5902: 5888: 5882: 5881: 5849: 5843: 5842: 5832: 5826: 5825: 5823: 5821: 5807: 5801: 5800: 5763: 5757: 5756: 5746: 5722: 5716: 5715: 5709: 5704: 5702: 5694: 5686: 5680: 5679: 5669: 5645: 5639: 5638: 5618: 5612: 5611: 5601: 5569: 5560: 5559: 5557: 5547: 5538: 5537: 5536: 5519: 5513: 5512: 5510: 5508: 5492: 5486: 5481:Adolphe Hirsch, 5479: 5473: 5472: 5466: 5457: 5451: 5450: 5448: 5446: 5430: 5424: 5423: 5398: 5392: 5391: 5385: 5383: 5362: 5356: 5355: 5353: 5338: 5337: 5332: 5326: 5325: 5293: 5287: 5286: 5284: 5267:Viik, T (2006). 5264: 5258: 5257: 5255: 5253: 5237: 5231: 5230: 5224: 5216: 5205: 5199: 5198: 5196: 5194: 5167: 5161: 5160: 5132: 5126: 5125: 5123: 5121: 5107: 5101: 5100: 5082: 5076: 5075: 5067: 5060: 5054: 5053: 5043: 5023: 5017: 5016: 4988: 4982: 4981: 4949: 4943: 4942: 4934: 4923: 4914: 4913: 4907: 4905: 4888: 4882: 4881: 4879: 4877: 4862: 4856: 4855: 4853: 4851: 4836: 4830: 4829: 4827: 4825: 4810: 4804: 4803: 4773: 4767: 4766: 4760: 4758: 4736: 4727: 4726: 4725: 4723: 4717: 4706: 4694: 4688: 4687: 4680: 4674: 4673: 4671: 4669: 4655: 4649: 4648: 4646: 4644: 4629: 4623: 4622: 4608: 4602: 4601: 4575: 4569: 4568: 4551: 4545: 4544: 4518: 4512: 4511: 4497: 4486: 4480: 4474: 4473: 4463: 4457: 4456: 4446: 4438: 4412: 4406: 4405: 4376: 4367: 4366: 4364: 4362: 4348: 4342: 4341: 4339: 4337: 4322: 4316: 4315: 4305: 4304: 4299: 4288: 4287: 4279: 4273: 4272: 4262: 4253: 4247: 4246: 4222: 4216: 4215: 4213: 4205: 4199: 4198: 4170: 4161: 4138: 4137: 4124: 4115: 4114: 4112: 4110: 4105:on 30 April 2017 4101:. Archived from 4091: 4085: 4084: 4082: 4080: 4071:. Archived from 4061: 4045: 4043: 4032: 4028: 4023: 4017: 4015: 4011: 4006: 4000: 3998: 3985: 3979: 3975: 3969: 3960: 3959: 3957: 3956: 3955: 3953: 3948: 3947: 3942: 3937: 3934: 3933: 3932: 3929: 3916: 3915: 3913: 3912: 3911: 3909: 3904: 3903: 3898: 3893: 3890: 3889: 3888: 3885: 3875: 3874: 3872: 3871: 3870: 3868: 3863: 3862: 3857: 3852: 3849: 3848: 3847: 3844: 3833: 3827: 3825: 3818: 3810: 3804: = 12 3802: 3794: 3786: = 12 3784: 3776: 3766: 3756: 3753:mesures usuelles 3747: 3739: 3732: 3726: 3718: 3712: 3710: 3708: 3707: 3702: 3700: 3699: 3698: 3669: 3667: 3666: 3661: 3659: 3652: 3645: 3644: 3640: 3618: 3616: 3615: 3610: 3605: 3604: 3599: 3595: 3590: 3589: 3585: 3572: 3548: 3546: 3545: 3540: 3538: 3537: 3533: 3513: 3511: 3510: 3505: 3500: 3491: 3490: 3468: 3462: 3460: 3459: 3456: 3453: 3442: 3436: 3434: 3433: 3426: 3378: 3368: 3367: 3363: 3350: 3314: 3292: 3278: 3270:First prototype 3261: 3240: 3239: 3235: 3211: 3207: 3185: 3175: 3174: 3171: 3165: 3153: 3152: 3148: 3131: 3104: 3019:refractive index 2999: 2961:Krypton standard 2916: 2912: 2911: 2907: 2869:Jean-René Benoît 2829:changed that of 2783:, who following 2710: 2702: 2687: 2685: 2684: 2676: 2642: 2631: 2552:Metre Convention 2530: 2514: 2502:Metre Convention 2484:Paris Conference 2259: 2251: 2186:defeated in the 2132:Hispanic America 2088: 1925:Kingdom of Italy 1842:repeating circle 1824: 1812:repeating circle 1746:would be. After 1717:Shetland Islands 1578:would represent 1462: 1461: 1458: 1451: 1449: 1448: 1445: 1442: 1394: 1316:Kingdom of Spain 1270: 1256: 1250: 1244: 1236: 1228: 1192: 1157: 1156: 1152: 1142:and another in " 1136:repeating circle 1117:Repeating circle 1094:Balearic Islands 997: 977: 976: 969: 949:seconds pendulum 937:Thomas Jefferson 905: 852:Metre Convention 845: 843: 842: 839: 836: 808:Emile Plantamour 782: 780: 779: 776: 773: 754: 752: 751: 748: 745: 730: 728: 727: 724: 721: 714: 712: 711: 708: 705: 694: 692: 691: 688: 685: 674: 672: 671: 668: 665: 637: 608:with variant of 556:seconds pendulum 535: 490: 479: 469: 457: 445: 438:is defined as 6 437: 416:seconds pendulum 378:seconds pendulum 217: 207: 206: 203: 197: 169:platinum-iridium 162: 146:Metre Convention 131: 120: 118: 117: 114: 111: 91:seconds pendulum 72: 57:starts with the 9934: 9933: 9929: 9928: 9927: 9925: 9924: 9923: 9904: 9903: 9880: 9875: 9868: 9847: 9843: 9826: 9817: 9806: 9805: 9801: 9761: 9756: 9752: 9702: 9698: 9679: 9678: 9674: 9633: 9629: 9588: 9584: 9550: 9543: 9502: 9498: 9465: 9461: 9452: 9450: 9440: 9439: 9435: 9393: 9387: 9380: 9359: 9358: 9354: 9325: 9321: 9306:Michelson, A.A. 9303: 9299: 9292: 9290: 9286: 9276: 9274: 9265: 9264: 9260: 9253: 9237: 9233: 9223: 9221: 9210: 9206: 9179: 9175: 9124: 9123: 9119: 9109: 9107: 9094: 9093: 9089: 9078: 9074: 9069:on 4 June 2024. 9059: 9055: 9038: 9037: 9033: 9025: 9017: 9013: 8982: 8978: 8969: 8967: 8963: 8957: 8946: 8935: 8928: 8895: 8888: 8879: 8877: 8862: 8861: 8857: 8847: 8845: 8834: 8827: 8818: 8814: 8769: 8765: 8752: 8751: 8747: 8736: 8729: 8716: 8712: 8701: 8700: 8696: 8649: 8645: 8635: 8633: 8625: 8624: 8620: 8611: 8609: 8599: 8598: 8585: 8576: 8574: 8565: 8561: 8549: 8543: 8539: 8532: 8525: 8508: 8507: 8500: 8485: 8481: 8471: 8469: 8458: 8454: 8425: 8421: 8411: 8409: 8401: 8400: 8393: 8383: 8381: 8373: 8372: 8368: 8358: 8356: 8355:. pp. 4, 8 8348: 8342: 8335: 8284: 8280: 8245: 8238: 8225: 8221: 8178: 8174: 8164: 8162: 8154: 8153: 8149: 8140: 8136: 8126: 8124: 8102: 8098: 8088: 8086: 8075: 8071: 8061: 8059: 8046: 8045: 8041: 8030: 8029: 8025: 8017: 8013: 7992: 7985: 7975: 7973: 7966: 7965: 7958: 7951: 7935: 7931: 7924: 7910: 7906: 7890: 7889: 7880: 7876: 7860: 7859: 7849: 7845: 7832: 7828: 7820: 7814: 7813: 7806: 7755: 7751: 7698: 7691: 7681: 7679: 7657: 7653: 7602: 7598: 7591: 7561: 7552: 7542: 7540: 7532: 7531: 7527: 7492: 7488: 7451: 7447: 7431: 7430: 7420: 7416: 7400: 7399: 7389: 7385: 7375: 7373: 7366: 7365: 7361: 7352: 7345: 7332: 7328: 7315: 7311: 7301: 7299: 7289: 7285: 7276: 7274: 7263: 7259: 7249: 7247: 7225: 7216: 7207: 7206: 7199: 7192: 7176: 7172: 7163: 7159: 7149: 7147: 7136: 7132: 7100:10.1.1.492.3967 7071: 7062: 7054: 7050: 7049: 7045: 7029: 7028: 7019: 7015: 6999: 6998: 6988: 6984: 6971: 6967: 6924: 6920: 6912:10.1.1.517.9501 6899: 6892: 6876: 6875: 6864: 6860: 6844: 6843: 6833: 6826: 6813: 6809: 6793: 6792: 6780: 6764: 6755: 6747: 6743: 6733: 6731: 6722: 6721: 6717: 6707: 6705: 6692: 6691: 6687: 6672: 6660: 6659: 6655: 6610: 6603: 6582: 6575: 6540: 6533: 6520: 6516: 6500: 6499: 6488: 6484: 6431: 6424: 6414: 6412: 6404: 6403: 6399: 6389: 6387: 6376: 6372: 6359: 6355: 6345: 6343: 6332: 6328: 6293: 6282: 6277: 6273: 6257: 6256: 6247: 6243: 6236: 6222: 6218: 6211: 6197: 6190: 6180: 6178: 6175:The Century Co. 6166: 6162: 6152: 6150: 6143: 6139: 6096: 6092: 6082: 6080: 6062: 6058: 6053: 6049: 6039: 6037: 6027: 6023: 6016: 6000: 5996: 5986: 5984: 5973: 5969: 5959: 5957: 5946: 5942: 5926: 5925: 5914: 5910: 5900: 5898: 5890: 5889: 5885: 5850: 5846: 5833: 5829: 5819: 5817: 5809: 5808: 5804: 5764: 5760: 5723: 5719: 5707: 5705: 5696: 5695: 5687: 5683: 5646: 5642: 5635: 5619: 5615: 5570: 5563: 5555: 5549: 5548: 5541: 5520: 5516: 5506: 5504: 5493: 5489: 5480: 5476: 5464: 5458: 5454: 5444: 5442: 5431: 5427: 5412: 5400: 5399: 5395: 5381: 5379: 5364: 5363: 5359: 5351: 5335: 5333: 5329: 5308:(7–8): 97–116. 5294: 5290: 5282:10.1.1.517.9501 5265: 5261: 5251: 5249: 5238: 5234: 5218: 5217: 5206: 5202: 5192: 5190: 5168: 5164: 5133: 5129: 5119: 5117: 5109: 5108: 5104: 5097: 5083: 5079: 5062: 5061: 5057: 5024: 5020: 5005: 4989: 4985: 4950: 4946: 4924: 4917: 4903: 4901: 4889: 4885: 4875: 4873: 4864: 4863: 4859: 4849: 4847: 4838: 4837: 4833: 4823: 4821: 4812: 4811: 4807: 4792: 4774: 4770: 4756: 4754: 4744:Arago, François 4737: 4730: 4721: 4719: 4718:on 20 June 2019 4715: 4704: 4695: 4691: 4682: 4681: 4677: 4667: 4665: 4656: 4652: 4642: 4640: 4631: 4630: 4626: 4609: 4605: 4590: 4576: 4572: 4552: 4548: 4533: 4519: 4515: 4498: 4489: 4481: 4477: 4464: 4460: 4440: 4439: 4427: 4413: 4409: 4394: 4377: 4370: 4360: 4358: 4350: 4349: 4345: 4335: 4333: 4323: 4319: 4302: 4300: 4291: 4280: 4276: 4260: 4254: 4250: 4223: 4219: 4211: 4207: 4206: 4202: 4168: 4162: 4141: 4126: 4125: 4118: 4108: 4106: 4093: 4092: 4088: 4078: 4076: 4063: 4062: 4058: 4054: 4049: 4048: 4041: 4039: 4030: 4026: 4024: 4020: 4013: 4009: 4007: 4003: 3996: 3986: 3982: 3976: 3972: 3951: 3949: 3945: 3943: 3939: 3938: 3935: 3930: 3927: 3925: 3923: 3922: 3921: 3919:Rodez Cathedral 3908:Rodez Cathedral 3907: 3905: 3901: 3899: 3895: 3894: 3891: 3886: 3883: 3881: 3879: 3878: 3877: 3867:Belfry, Dunkirk 3866: 3864: 3860: 3858: 3854: 3853: 3850: 3845: 3842: 3840: 3838: 3837: 3836: 3834: 3830: 3820: = 1 3768: = 6 3733: 3729: 3719: 3715: 3694: 3690: 3683: 3675: 3672: 3671: 3655: 3636: 3632: 3628: 3626: 3623: 3622: 3600: 3581: 3577: 3573: 3571: 3567: 3566: 3555: 3552: 3551: 3529: 3525: 3521: 3519: 3516: 3515: 3489: 3475: 3472: 3471: 3469: 3465: 3457: 3454: 3451: 3449: 3444:Since 2012 the 3443: 3439: 3431: 3429: 3427: 3423: 3418: 3391: 3376: 3365: 3361: 3360: 3348: 3312: 3290: 3259: 3237: 3233: 3232: 3226: 3221: 3206: 3184: 3177: 3172: 3169: 3167: 3163: 3150: 3146: 3145: 3129: 3102: 3056: 3031: 3007: 3003: 2997: 2963: 2914: 2909: 2905: 2904: 2861:interferometric 2849: 2844: 2843: 2795:had questioned 2781:Albert Einstein 2772:application of 2733: 2682: 2680: 2679: 2668:Johnson Matthey 2548: 2547: 2349:, a second for 2322:Committee Meter 2273: 2176:standardization 2116:Napoleonic Wars 2108: 2103: 2102: 2077:First World War 1885:Austrian Empire 1825: 1822: 1744:Earth ellipsoid 1478: 1470: 1469: 1459: 1456: 1454: 1446: 1443: 1440: 1439: 1437: 1436:and a value of 1413: 1396: 1384:Gaspar de Prony 1356:Barnabé Brisson 1340:Tuscan Republic 1292:Henricus Aeneae 1210:Rodez Cathedral 1202:Rodez Cathedral 1154: 1150: 1149: 1050:Montjuïc Castle 1020: 1002: 978: 974: 967: 939:and others for 840: 837: 834: 833: 831: 777: 774: 771: 770: 768: 749: 746: 743: 742: 740: 725: 722: 719: 718: 716: 709: 706: 703: 702: 700: 689: 686: 683: 682: 680: 669: 666: 663: 662: 660: 630:Earth ellipsoid 618:Alexis Clairaut 584:oblate spheroid 524:radius of Earth 488:metro cattolico 232: 216: 209: 204: 201: 199: 195: 173:standardization 115: 112: 109: 108: 106: 17: 12: 11: 5: 9932: 9922: 9921: 9916: 9902: 9901: 9887:, ed. (1911). 9885:Chisholm, Hugh 9879: 9878:External links 9876: 9874: 9873: 9866: 9841: 9815: 9799: 9772:(3): 136–138. 9765:Optics Letters 9759: 9750: 9715:(3): 133–135. 9708:Optics Letters 9696: 9672: 9645:(3): 133–134. 9627: 9600:(4): 196–199. 9582: 9541: 9496: 9477:(5): 455–463. 9470:Applied Optics 9459: 9433: 9378: 9352: 9329:Fabry, Charles 9319: 9297: 9284: 9258: 9251: 9231: 9204: 9173: 9117: 9087: 9072: 9053: 9031: 9011: 8992:(5): 419–422. 8976: 8955: 8926: 8907:(6): 415–434. 8886: 8855: 8842:NobelPrize.org 8825: 8812: 8763: 8745: 8727: 8710: 8694: 8659:(9): 558–568. 8643: 8618: 8583: 8559: 8537: 8523: 8498: 8479: 8452: 8419: 8391: 8366: 8333: 8278: 8236: 8219: 8172: 8147: 8134: 8096: 8069: 8039: 8023: 8019:Bigourdan 1901 8011: 7983: 7956: 7949: 7929: 7922: 7904: 7874: 7843: 7826: 7804: 7749: 7689: 7651: 7616:(3): 248–313. 7596: 7589: 7550: 7525: 7486: 7445: 7414: 7383: 7359: 7343: 7326: 7309: 7283: 7257: 7239:(7): 377–378. 7214: 7197: 7190: 7170: 7157: 7130: 7085:(3): 176–188. 7060: 7043: 7013: 6982: 6965: 6918: 6890: 6858: 6824: 6807: 6778: 6753: 6741: 6728:hls-dhs-dss.ch 6715: 6698:public.wmo.int 6685: 6670: 6653: 6601: 6573: 6554:(2): 117–129. 6531: 6514: 6482: 6422: 6397: 6384:FranceArchives 6370: 6367:. p. 163. 6353: 6326: 6280: 6271: 6241: 6235:978-0349115078 6234: 6216: 6209: 6188: 6177:pp. 10–11 6160: 6137: 6110:(4): 355–372. 6090: 6056: 6047: 6021: 6014: 5994: 5967: 5954:FranceArchives 5940: 5908: 5883: 5844: 5827: 5802: 5758: 5717: 5708:|journal= 5681: 5660:(4): 355–372. 5640: 5633: 5613: 5561: 5539: 5514: 5487: 5474: 5452: 5425: 5410: 5393: 5357: 5327: 5288: 5259: 5232: 5200: 5162: 5127: 5102: 5095: 5077: 5055: 5018: 5003: 4983: 4944: 4929:, ed. (1911). 4927:Chisholm, Hugh 4915: 4883: 4857: 4831: 4805: 4790: 4768: 4728: 4689: 4675: 4650: 4624: 4603: 4588: 4570: 4546: 4531: 4513: 4487: 4483:Bigourdan 1901 4475: 4472:. p. 403. 4458: 4425: 4407: 4392: 4368: 4343: 4317: 4289: 4274: 4248: 4237:(3): 352–356. 4217: 4200: 4181:(9): 596–613. 4139: 4116: 4086: 4055: 4053: 4050: 4047: 4046: 4037: 4018: 4001: 3991:) defined the 3980: 3970: 3828: 3812:; so 864 3744:toise de Pérou 3734:All values in 3727: 3713: 3697: 3693: 3689: 3686: 3682: 3679: 3658: 3651: 3648: 3643: 3639: 3635: 3631: 3620: 3619: 3608: 3603: 3598: 3593: 3588: 3584: 3580: 3576: 3570: 3565: 3562: 3559: 3536: 3532: 3528: 3524: 3503: 3497: 3494: 3488: 3485: 3482: 3479: 3463: 3437: 3420: 3419: 3417: 3414: 3413: 3412: 3407: 3402: 3397: 3390: 3387: 3384: 3383: 3380: 3373: 3370: 3356: 3355: 3352: 3345: 3342: 3334: 3333: 3330: 3327: 3324: 3320: 3319: 3316: 3309: 3306: 3298: 3297: 3294: 3287: 3284: 3267: 3266: 3263: 3256: 3253: 3229: 3228: 3223: 3218: 3215: 3205: 3202: 3188: 3187: 3182: 3156: 3155: 3095:speed of light 3030: 3027: 3005: 3001: 2975:Doppler effect 2962: 2959: 2848: 2845: 2799:in 1687 after 2734: 2726: 2660:Tresca section 2608:Adolphe Hirsch 2318:Étienne Lenoir 2296:At that time, 2282:Johnson Mattey 2274: 2266: 2235:Adolphe Hirsch 2160:Ottoman Empire 2107: 2104: 2073:British Empire 2009:Central Europe 1933:Russian Empire 1881:Central Europe 1854:Leonhard Euler 1820: 1729:Paris meridian 1626:canton of Bern 1607:Paris meridian 1599:Louis Puissant 1479: 1471: 1414: 1406: 1395: 1388: 1368:René Just Haüy 1336:Roman Republic 1171:Pierre Méchain 1132:decimalisation 1125:Étienne Lenoir 1102:François Arago 1004: 1003: 981: 979: 972: 966: 963: 912:British Empire 903:Toise de Paris 824:Adolphe Hirsch 550:found out the 520:solar parallax 412:Paris meridian 347:Paris meridian 278:cubit into 28 270:. Indeed, the 231: 228: 220: 219: 214: 185:speed of light 31:Earth quadrant 15: 9: 6: 4: 3: 2: 9931: 9920: 9917: 9915: 9912: 9911: 9909: 9898: 9897: 9891: 9886: 9882: 9881: 9869: 9863: 9860: 9855: 9854: 9845: 9837: 9836: 9835:New Scientist 9831: 9824: 9822: 9820: 9811: 9810: 9803: 9795: 9791: 9787: 9783: 9779: 9775: 9771: 9767: 9766: 9754: 9746: 9742: 9738: 9734: 9730: 9726: 9722: 9718: 9714: 9710: 9709: 9700: 9692: 9688: 9684: 9683: 9676: 9668: 9664: 9660: 9656: 9652: 9648: 9644: 9640: 9639: 9631: 9623: 9619: 9615: 9611: 9607: 9603: 9599: 9595: 9594: 9586: 9578: 9574: 9570: 9566: 9562: 9558: 9557: 9548: 9546: 9537: 9533: 9529: 9525: 9521: 9517: 9513: 9509: 9508: 9500: 9492: 9488: 9484: 9480: 9476: 9472: 9471: 9463: 9449: 9445: 9444: 9437: 9429: 9425: 9421: 9417: 9413: 9409: 9405: 9401: 9400: 9392: 9385: 9383: 9375: 9371: 9367: 9364:(in French). 9363: 9356: 9348: 9345:(in French). 9344: 9343: 9338: 9334: 9330: 9323: 9315: 9312:(in French). 9311: 9307: 9301: 9288: 9272: 9268: 9262: 9254: 9248: 9244: 9243: 9235: 9219: 9215: 9208: 9200: 9196: 9192: 9188: 9184: 9177: 9169: 9165: 9161: 9157: 9152: 9147: 9143: 9139: 9135: 9131: 9127: 9121: 9105: 9101: 9097: 9091: 9083: 9076: 9068: 9064: 9057: 9050: 9045: 9041: 9035: 9024: 9023: 9015: 9007: 9003: 8999: 8995: 8991: 8987: 8980: 8962: 8958: 8956:92-822-2213-6 8952: 8945: 8944: 8939: 8933: 8931: 8922: 8918: 8914: 8910: 8906: 8902: 8901: 8893: 8891: 8875: 8871: 8867: 8866: 8859: 8844:. p. 448 8843: 8839: 8832: 8830: 8822: 8816: 8808: 8804: 8799: 8794: 8790: 8786: 8782: 8778: 8774: 8767: 8759: 8755: 8749: 8741: 8734: 8732: 8723: 8722: 8714: 8706: 8705: 8698: 8690: 8686: 8682: 8678: 8674: 8670: 8666: 8662: 8658: 8654: 8647: 8632: 8628: 8622: 8608: 8604: 8603: 8596: 8594: 8592: 8590: 8588: 8572: 8571: 8563: 8555: 8548: 8541: 8535: 8530: 8528: 8519: 8518: 8512: 8505: 8503: 8494: 8490: 8483: 8467: 8463: 8456: 8447: 8442: 8438: 8434: 8430: 8423: 8408: 8404: 8398: 8396: 8380: 8376: 8370: 8354: 8347: 8340: 8338: 8329: 8325: 8321: 8317: 8313: 8309: 8305: 8301: 8298:(12): 39–44. 8297: 8293: 8292:Physics Today 8289: 8282: 8274: 8270: 8266: 8262: 8258: 8254: 8250: 8243: 8241: 8232: 8231: 8223: 8215: 8211: 8207: 8203: 8199: 8195: 8191: 8187: 8183: 8176: 8161: 8157: 8151: 8144: 8138: 8123: 8119: 8115: 8112:(in German). 8111: 8107: 8100: 8084: 8080: 8073: 8057: 8053: 8049: 8043: 8035: 8034: 8027: 8020: 8015: 8007: 8003: 7999: 7998: 7990: 7988: 7971: 7970: 7963: 7961: 7952: 7946: 7942: 7941: 7933: 7925: 7919: 7915: 7908: 7900: 7894: 7887: 7886: 7878: 7870: 7864: 7856: 7855: 7847: 7839: 7838: 7830: 7819: 7818: 7811: 7809: 7800: 7796: 7792: 7788: 7784: 7780: 7776: 7772: 7768: 7764: 7760: 7753: 7745: 7741: 7737: 7733: 7728: 7723: 7719: 7715: 7711: 7707: 7703: 7696: 7694: 7678: 7674: 7670: 7667:(in French). 7666: 7662: 7655: 7647: 7643: 7639: 7635: 7631: 7627: 7623: 7619: 7615: 7612:(in French). 7611: 7607: 7600: 7592: 7586: 7582: 7578: 7574: 7570: 7569:IAG 150 Years 7566: 7559: 7557: 7555: 7539: 7535: 7529: 7521: 7517: 7513: 7509: 7505: 7501: 7497: 7490: 7482: 7478: 7473: 7468: 7464: 7460: 7456: 7449: 7441: 7435: 7427: 7426: 7418: 7410: 7404: 7396: 7395: 7387: 7372: 7369: 7363: 7356: 7350: 7348: 7339: 7338: 7330: 7322: 7321: 7313: 7298: 7294: 7287: 7272: 7268: 7261: 7246: 7242: 7238: 7235:(in French). 7234: 7230: 7223: 7221: 7219: 7210: 7204: 7202: 7193: 7187: 7183: 7182: 7174: 7167: 7161: 7145: 7141: 7134: 7126: 7122: 7118: 7114: 7110: 7106: 7101: 7096: 7092: 7088: 7084: 7080: 7076: 7069: 7067: 7065: 7053: 7047: 7039: 7033: 7026: 7025: 7017: 7009: 7003: 6995: 6994: 6986: 6978: 6977: 6969: 6961: 6957: 6953: 6949: 6945: 6941: 6937: 6933: 6929: 6922: 6913: 6908: 6904: 6897: 6895: 6886: 6880: 6872: 6871: 6862: 6854: 6848: 6840: 6839: 6831: 6829: 6820: 6819: 6811: 6803: 6797: 6789: 6785: 6781: 6775: 6771: 6770: 6762: 6760: 6758: 6750: 6745: 6729: 6725: 6719: 6703: 6699: 6695: 6689: 6681: 6677: 6673: 6667: 6663: 6657: 6649: 6645: 6640: 6635: 6631: 6627: 6623: 6619: 6615: 6608: 6606: 6597: 6592: 6588: 6580: 6578: 6569: 6565: 6561: 6557: 6553: 6549: 6545: 6538: 6536: 6527: 6526: 6518: 6510: 6504: 6496: 6495: 6486: 6478: 6474: 6470: 6466: 6461: 6456: 6452: 6448: 6444: 6440: 6436: 6429: 6427: 6411: 6407: 6401: 6385: 6381: 6374: 6366: 6365: 6357: 6341: 6337: 6330: 6322: 6318: 6314: 6310: 6306: 6302: 6298: 6291: 6289: 6287: 6285: 6275: 6267: 6261: 6254: 6253: 6245: 6237: 6231: 6227: 6220: 6212: 6210:0-349-11507-9 6206: 6202: 6195: 6193: 6176: 6173: 6172: 6164: 6148: 6141: 6133: 6129: 6125: 6121: 6117: 6113: 6109: 6105: 6101: 6094: 6079: 6075: 6071: 6067: 6060: 6051: 6036: 6032: 6025: 6017: 6011: 6007: 6006: 5998: 5982: 5978: 5971: 5955: 5951: 5944: 5936: 5930: 5922: 5921: 5912: 5897: 5893: 5887: 5879: 5875: 5871: 5867: 5863: 5859: 5855: 5848: 5840: 5839: 5831: 5816: 5812: 5806: 5798: 5794: 5790: 5786: 5782: 5778: 5774: 5770: 5762: 5754: 5750: 5745: 5740: 5736: 5732: 5728: 5721: 5713: 5700: 5692: 5685: 5677: 5673: 5668: 5663: 5659: 5655: 5651: 5644: 5636: 5634:9780387755342 5630: 5626: 5625: 5617: 5609: 5605: 5600: 5595: 5591: 5587: 5583: 5579: 5575: 5568: 5566: 5554: 5553: 5546: 5544: 5535: 5530: 5526: 5518: 5502: 5498: 5491: 5484: 5478: 5470: 5463: 5456: 5440: 5436: 5429: 5421: 5417: 5413: 5407: 5403: 5397: 5389: 5377: 5373: 5372: 5367: 5361: 5350: 5349: 5342: 5341:public domain 5331: 5323: 5319: 5315: 5311: 5307: 5303: 5299: 5292: 5283: 5278: 5274: 5270: 5263: 5247: 5243: 5236: 5228: 5222: 5214: 5213: 5204: 5189: 5185: 5181: 5178:(in French). 5177: 5173: 5166: 5158: 5154: 5150: 5146: 5142: 5138: 5131: 5116: 5112: 5106: 5098: 5092: 5088: 5081: 5073: 5072: 5066: 5059: 5051: 5047: 5042: 5037: 5033: 5029: 5022: 5014: 5010: 5006: 5000: 4996: 4995: 4987: 4979: 4975: 4971: 4967: 4963: 4959: 4955: 4948: 4940: 4939: 4933: 4928: 4922: 4920: 4911: 4899: 4898: 4893: 4887: 4871: 4870:clea-astro.eu 4867: 4861: 4845: 4841: 4835: 4819: 4815: 4809: 4801: 4797: 4793: 4791:9782804184964 4787: 4783: 4779: 4772: 4764: 4752: 4751: 4745: 4741: 4735: 4733: 4714: 4710: 4703: 4699: 4693: 4685: 4679: 4663: 4662: 4654: 4638: 4634: 4628: 4620: 4616: 4615: 4607: 4599: 4595: 4591: 4589:9782804184964 4585: 4581: 4574: 4566: 4562: 4561: 4556: 4550: 4542: 4538: 4534: 4528: 4524: 4517: 4509: 4505: 4504: 4496: 4494: 4492: 4484: 4479: 4471: 4470: 4462: 4454: 4450: 4444: 4436: 4432: 4428: 4426:9782804184964 4422: 4418: 4411: 4403: 4399: 4395: 4393:9782757824900 4389: 4385: 4381: 4375: 4373: 4357: 4353: 4347: 4332: 4328: 4321: 4313: 4312: 4298: 4296: 4294: 4285: 4278: 4270: 4266: 4259: 4252: 4244: 4240: 4236: 4232: 4228: 4221: 4210: 4204: 4196: 4192: 4188: 4184: 4180: 4176: 4175: 4167: 4160: 4158: 4156: 4154: 4152: 4150: 4148: 4146: 4144: 4135: 4131: 4130: 4123: 4121: 4104: 4100: 4096: 4090: 4074: 4070: 4066: 4060: 4056: 4036: 4022: 4005: 3994: 3990: 3984: 3974: 3968: 3964: 3958: 3920: 3914: 3873: 3832: 3824: 3819: 3817: 3811: 3809: 3803: 3801: 3795: 3793: 3792: 3785: 3783: 3777: 3775: 3774: 3767: 3765: 3764: 3757: 3755: 3754: 3746: 3745: 3738: 3731: 3724: 3717: 3695: 3691: 3687: 3684: 3680: 3677: 3649: 3646: 3641: 3637: 3633: 3629: 3606: 3601: 3596: 3591: 3586: 3582: 3578: 3574: 3568: 3563: 3560: 3557: 3550: 3549: 3534: 3530: 3526: 3522: 3501: 3495: 3492: 3486: 3483: 3480: 3477: 3467: 3447: 3441: 3425: 3421: 3411: 3408: 3406: 3403: 3401: 3398: 3396: 3393: 3392: 3381: 3374: 3371: 3358: 3357: 3353: 3346: 3343: 3340: 3336: 3335: 3331: 3328: 3325: 3322: 3321: 3317: 3310: 3307: 3304: 3300: 3299: 3295: 3288: 3285: 3283: 3280:platinum bar 3279: 3277: 3276: 3269: 3268: 3264: 3257: 3254: 3252: 3248: 3244: 3231: 3230: 3224: 3219: 3216: 3213: 3212: 3201: 3198: 3194: 3193:caesium clock 3181: 3161: 3160: 3159: 3143: 3142: 3141: 3139: 3133: 3127: 3123: 3119: 3115: 3111: 3106: 3100: 3096: 3090: 3088: 3084: 3080: 3075: 3073: 3069: 3065: 3061: 3055: 3048: 3047:Univ. Paris 6 3044: 3040: 3035: 3026: 3024: 3020: 3015: 3009: 2993: 2991: 2986: 2984: 2980: 2976: 2972: 2968: 2958: 2956: 2952: 2948: 2943: 2941: 2936: 2930: 2928: 2922: 2920: 2902: 2898: 2894: 2890: 2886: 2882: 2878: 2874: 2870: 2866: 2862: 2853: 2840: 2836: 2832: 2828: 2824: 2820: 2816: 2813:Furthermore, 2812: 2810: 2809:French Guiana 2806: 2802: 2798: 2794: 2790: 2786: 2782: 2777: 2775: 2771: 2770:technological 2767: 2763: 2759: 2755: 2751: 2747: 2738: 2731: 2725: 2723: 2719: 2718:Bessel points 2713: 2711: 2709: 2703: 2701: 2693: 2689: 2677: 2675: 2669: 2665: 2661: 2657: 2654:and 10% 2653: 2648: 2644: 2641: 2634: 2632: 2630: 2629: 2622: 2617: 2615: 2614: 2609: 2605: 2601: 2597: 2593: 2589: 2588:German Empire 2585: 2581: 2577: 2576:meteorologist 2573: 2569: 2565: 2561: 2557: 2553: 2545: 2541: 2537: 2536: 2531: 2529: 2523: 2519: 2515: 2513: 2507: 2503: 2499: 2497: 2496:metric system 2493: 2489: 2485: 2479: 2477: 2476:metric system 2473: 2469: 2465: 2461: 2456: 2454: 2449: 2439: 2435: 2433: 2429: 2425: 2421: 2416: 2412: 2408: 2404: 2399: 2397: 2393: 2389: 2385: 2381: 2376: 2366: 2362: 2360: 2356: 2352: 2348: 2344: 2340: 2336: 2332: 2327: 2323: 2319: 2315: 2311: 2307: 2303: 2299: 2291: 2287: 2283: 2278: 2271: 2265: 2263: 2258: 2257: 2250: 2244: 2240: 2236: 2232: 2231:metric system 2228: 2224: 2220: 2215: 2213: 2209: 2205: 2201: 2200:German Empire 2197: 2193: 2189: 2185: 2181: 2177: 2174:and a better 2173: 2169: 2165: 2161: 2157: 2153: 2149: 2145: 2141: 2137: 2133: 2129: 2125: 2121: 2120:Latin America 2117: 2113: 2100: 2096: 2092: 2087: 2082: 2078: 2074: 2071:in 1889; and 2070: 2069:United-States 2066: 2062: 2058: 2054: 2050: 2048: 2044: 2040: 2036: 2032: 2028: 2027:French Empire 2024: 2020: 2016: 2012: 2010: 2006: 2002: 1998: 1994: 1990: 1986: 1982: 1978: 1974: 1970: 1966: 1962: 1957: 1952: 1950: 1946: 1943:, as well as 1942: 1938: 1934: 1930: 1926: 1922: 1918: 1914: 1910: 1906: 1902: 1898: 1894: 1890: 1886: 1882: 1878: 1874: 1869: 1867: 1863: 1859: 1855: 1852:predicted by 1851: 1847: 1843: 1839: 1830: 1819: 1813: 1809: 1805: 1801: 1797: 1793: 1789: 1785: 1781: 1777: 1773: 1769: 1765: 1761: 1757: 1753: 1749: 1745: 1741: 1737: 1730: 1726: 1722: 1718: 1713: 1709: 1707: 1703: 1699: 1695: 1691: 1687: 1683: 1679: 1675: 1670: 1666: 1662: 1658: 1654: 1649: 1646:district, in 1645: 1641: 1637: 1631: 1627: 1623: 1618: 1614: 1612: 1608: 1604: 1600: 1596: 1592: 1587: 1585: 1581: 1577: 1573: 1569: 1565: 1564: 1558: 1554: 1550: 1546: 1542: 1538: 1534: 1530: 1526: 1522: 1517: 1515: 1511: 1510:United States 1506: 1504: 1500: 1496: 1488: 1487:New York City 1483: 1476: 1467: 1435: 1430: 1429:triangulation 1426: 1422: 1418: 1411: 1400: 1393: 1387: 1385: 1381: 1377: 1373: 1369: 1365: 1361: 1357: 1353: 1349: 1345: 1341: 1337: 1333: 1329: 1325: 1321: 1317: 1313: 1309: 1305: 1301: 1297: 1293: 1289: 1284: 1282: 1278: 1274: 1269: 1264: 1260: 1255: 1249: 1243: 1242: 1235: 1234: 1227: 1221: 1219: 1215: 1211: 1203: 1198: 1194: 1191: 1190: 1184: 1180: 1176: 1172: 1168: 1163: 1161: 1147: 1146: 1141: 1137: 1133: 1126: 1122: 1118: 1114: 1110: 1108: 1103: 1099: 1095: 1091: 1087: 1083: 1079: 1075: 1071: 1067: 1063: 1055: 1051: 1047: 1041: 1037: 1033: 1029: 1024: 1019: 1015: 1011: 1000: 999:(August 2020) 995: 991: 990: 985: 980: 971: 970: 962: 959: 954: 950: 946: 945:British Crown 942: 938: 934: 929: 924: 920: 915: 913: 909: 904: 899: 895: 891: 887: 883: 876: 871: 867: 865: 861: 857: 853: 849: 829: 825: 821: 817: 813: 809: 805: 801: 800:Adolf Repsold 796: 794: 790: 786: 766: 765:least squares 762: 758: 738: 734: 698: 678: 658: 653: 649: 645: 641: 636: 631: 627: 623: 619: 616:According to 611: 607: 603: 599: 597: 593: 589: 585: 581: 577: 573: 569: 565: 561: 557: 553: 549: 545: 543: 539: 534: 529: 525: 521: 517: 516:French Guiana 513: 509: 505: 501: 499: 495: 491: 489: 483: 478: 473: 468: 467: 462:] or 864 461: 456: 455: 449: 444: 443: 436: 435: 429: 425: 421: 417: 413: 409: 408:triangulation 405: 401: 397: 393: 389: 387: 383: 379: 375: 371: 367: 363: 359: 355: 348: 344: 339: 335: 333: 329: 326:included six 325: 321: 317: 312: 308: 305:to 5 feet. A 304: 300: 296: 292: 288: 283: 281: 277: 273: 269: 265: 261: 257: 252: 244: 240: 236: 227: 225: 213: 194: 190: 189: 188: 186: 182: 177: 174: 170: 166: 161: 160: 153: 151: 147: 143: 139: 135: 130: 129: 122: 104: 100: 96: 92: 88: 84: 83:Ancien Régime 80: 75: 71: 70: 64: 60: 56: 48: 44: 40: 36: 32: 28: 23: 19: 9894: 9852: 9844: 9833: 9808: 9802: 9769: 9763: 9753: 9712: 9706: 9699: 9681: 9675: 9642: 9636: 9630: 9597: 9591: 9585: 9560: 9554: 9511: 9505: 9499: 9474: 9468: 9462: 9451:, retrieved 9442: 9436: 9403: 9397: 9365: 9361: 9355: 9349:: 1082–1086. 9346: 9340: 9322: 9313: 9309: 9300: 9295:, p. 816–817 9287: 9275:. Retrieved 9270: 9261: 9241: 9234: 9222:. Retrieved 9217: 9207: 9190: 9186: 9176: 9133: 9129: 9120: 9108:. Retrieved 9104:the original 9100:www.bipm.org 9099: 9090: 9081: 9075: 9067:the original 9056: 9047: 9043: 9034: 9021: 9014: 8989: 8985: 8979: 8968:, retrieved 8942: 8904: 8898: 8878:, retrieved 8874:the original 8864: 8858: 8846:. Retrieved 8841: 8815: 8780: 8776: 8766: 8757: 8748: 8739: 8720: 8713: 8703: 8697: 8656: 8652: 8646: 8636:19 September 8634:. Retrieved 8631:IAG Homepage 8630: 8621: 8610:, retrieved 8601: 8577:20 September 8575:, retrieved 8569: 8562: 8553: 8540: 8515: 8492: 8488: 8482: 8470:. Retrieved 8465: 8455: 8436: 8432: 8422: 8410:. Retrieved 8407:IAG Homepage 8406: 8382:. Retrieved 8379:www.bipm.org 8378: 8369: 8357:. Retrieved 8352: 8295: 8291: 8281: 8256: 8253:L'Astronomie 8252: 8229: 8222: 8189: 8185: 8175: 8163:. Retrieved 8159: 8150: 8142: 8137: 8125:. Retrieved 8113: 8109: 8099: 8087:. Retrieved 8082: 8072: 8060:. Retrieved 8056:the original 8051: 8042: 8032: 8026: 8014: 7996: 7974:. Retrieved 7968: 7939: 7932: 7913: 7907: 7884: 7877: 7853: 7846: 7836: 7829: 7816: 7766: 7762: 7752: 7709: 7705: 7680:. Retrieved 7668: 7664: 7654: 7613: 7609: 7599: 7572: 7568: 7541:. Retrieved 7537: 7528: 7503: 7499: 7489: 7462: 7458: 7448: 7424: 7417: 7397:p. 419. 7393: 7386: 7374:. Retrieved 7370: 7362: 7354: 7336: 7329: 7319: 7312: 7300:. Retrieved 7296: 7286: 7275:, retrieved 7270: 7260: 7248:. Retrieved 7236: 7232: 7180: 7173: 7165: 7160: 7148:. Retrieved 7143: 7133: 7082: 7078: 7046: 7023: 7016: 6992: 6985: 6975: 6968: 6935: 6931: 6921: 6902: 6868: 6861: 6837: 6817: 6810: 6768: 6748: 6744: 6732:. Retrieved 6727: 6718: 6706:. Retrieved 6702:the original 6697: 6688: 6661: 6656: 6621: 6617: 6586: 6551: 6547: 6524: 6517: 6494:Delambre,... 6492: 6485: 6442: 6438: 6413:. Retrieved 6409: 6400: 6388:. Retrieved 6383: 6373: 6363: 6356: 6344:. Retrieved 6339: 6329: 6304: 6300: 6274: 6251: 6244: 6225: 6219: 6200: 6179:. Retrieved 6170: 6163: 6151:. Retrieved 6140: 6107: 6103: 6093: 6081:. Retrieved 6069: 6059: 6050: 6038:. Retrieved 6034: 6024: 6004: 5997: 5985:. Retrieved 5980: 5970: 5958:. Retrieved 5953: 5943: 5918: 5911: 5899:. Retrieved 5895: 5886: 5861: 5858:L'Astronomie 5857: 5847: 5837: 5830: 5818:. Retrieved 5814: 5805: 5772: 5768: 5761: 5734: 5730: 5720: 5699:cite journal 5684: 5657: 5653: 5643: 5623: 5616: 5581: 5577: 5551: 5524: 5517: 5505:. Retrieved 5500: 5490: 5482: 5477: 5468: 5455: 5443:. Retrieved 5438: 5428: 5401: 5396: 5386:– via 5380:. Retrieved 5375: 5369: 5360: 5347: 5330: 5305: 5301: 5291: 5272: 5262: 5250:. Retrieved 5245: 5235: 5212:Delambre,... 5210: 5203: 5191:. Retrieved 5179: 5175: 5165: 5140: 5136: 5130: 5118:. Retrieved 5114: 5105: 5086: 5080: 5069: 5058: 5031: 5021: 4993: 4986: 4964:: 117–129 . 4961: 4957: 4947: 4936: 4908:– via 4902:. Retrieved 4896: 4892:Picard, Jean 4886: 4874:. Retrieved 4869: 4860: 4848:. Retrieved 4843: 4834: 4822:. Retrieved 4817: 4808: 4781: 4777: 4771: 4761:– via 4757:14 September 4755:. Retrieved 4748: 4720:, retrieved 4713:the original 4708: 4692: 4683: 4678: 4666:. Retrieved 4660: 4653: 4641:. Retrieved 4636: 4627: 4613: 4606: 4579: 4573: 4559: 4555:Picard, Jean 4549: 4522: 4516: 4502: 4478: 4468: 4461: 4416: 4410: 4383: 4380:Guedj, Denis 4359:. Retrieved 4355: 4346: 4334:. Retrieved 4330: 4320: 4309: 4283: 4277: 4268: 4264: 4251: 4234: 4230: 4220: 4203: 4178: 4172: 4128: 4107:. Retrieved 4103:the original 4099:www.bipm.org 4098: 4089: 4077:. Retrieved 4073:the original 4069:www.bipm.org 4068: 4059: 4034: 4021: 4004: 3983: 3973: 3831: 3813: 3805: 3797: 3787: 3779: 3769: 3759: 3749: 3730: 3716: 3670:, therefore 3466: 3440: 3424: 3395:Hebdomometre 3341:(11th CGPM) 3271: 3227:uncertainty 3222:uncertainty 3189: 3179: 3157: 3154:of a second. 3134: 3121: 3113: 3109: 3107: 3091: 3086: 3081:-stabilised 3076: 3060:triple point 3057: 3013: 3011: 2998:1 650 763.73 2995: 2987: 2982: 2964: 2944: 2940:nuclear spin 2931: 2923: 2888: 2858: 2778: 2768:to become a 2743: 2715: 2705: 2697: 2695: 2690: 2671: 2664:Henri Tresca 2649: 2645: 2635: 2624: 2618: 2612: 2549: 2533: 2525: 2509: 2505: 2480: 2457: 2444: 2431: 2400: 2372: 2321: 2313: 2295: 2285: 2261: 2241:and Colonel 2216: 2182:in 1815 and 2134:, while the 2124:independence 2109: 2037:represented 2013: 1997:Adriatic Sea 1953: 1870: 1850:Polar motion 1835: 1816: 1720: 1704:had founded 1702:Eratosthenes 1698:meridian arc 1690:South Africa 1669:Jean Brunner 1640:Muhammad Ali 1634: 1588: 1561: 1523:studied the 1518: 1507: 1492: 1312:Thomas Bugge 1285: 1222: 1207: 1183:yellow fever 1167:meridian arc 1164: 1159: 1143: 1129: 1059: 1036:meridian arc 998: 987: 916: 879: 797: 615: 596:Earth radius 546: 538:Isaac Newton 502: 485: 450:] or 72 423: 390: 352: 284: 274:divided the 248: 221: 211: 178: 154: 123: 94: 85:, including 76: 54: 52: 18: 9273:(in French) 9220:(in French) 9193:: 242–263. 8970:16 December 8819:Article 3, 8439:: 445–469. 8259:: 244–245. 8192:(13): 193. 7769:(10): 914. 7465:: 147–162. 6730:(in German) 6445:(1): 6–21. 6386:(in French) 6070:E-Periodica 6035:www.bbc.com 5956:(in French) 5864:: 242–249. 5775:: 161–180. 5737:: 445–469. 5584:(1): 6–21. 5215:p. 10. 5193:4 September 5143:: 117–129. 4904:5 September 4876:5 September 4872:(in French) 4850:5 September 4824:5 September 4820:(in French) 4637:humanite.fr 4510:, 148, 154. 4079:13 November 4040: = 3.5 3997:6438.469 63 3944: / 3900: / 3859: / 3723:atomic time 3435:arcseconds. 3366:299,792,458 3151:299,792,458 3118:uncertainty 3105: THz. 2801:Jean Richer 2746:thermometry 2411:Koenigsberg 2204:cartography 2172:metrication 2021:joined the 1945:Switzerland 1929:Netherlands 1909:Mecklenburg 1630:Switzerland 1591:Fire Island 1364:Jean Darcet 1119:devised by 884:and in the 804:Switzerland 759:. In 1841, 733:arc of Peru 560:cartography 528:Jean Picard 504:Jean Richer 494:Jean Richer 404:Jean Picard 364:discovered 356:began with 249:The Nippur 241:, with the 9908:Categories 9218:Libération 7682:11 October 7376:12 October 7250:12 October 6153:13 October 6083:12 October 5820:15 October 5382:10 October 5013:1061216207 4532:2711753476 4361:15 October 4336:15 October 4052:References 3950: ( 3928:41°21′48″N 3906: ( 3884:44°25′57″N 3865: ( 3843:51°02′08″N 3347:0.01–0.005 3339:krypton-86 3238:10,000,000 3052:See also: 2979:krypton-86 2971:broadening 2885:wavelength 2859:The first 2686:m ± 0.2 μm 2388:gravimetry 2237:, General 2122:following 2110:After the 2047:Hervé Faye 2005:Baltic Sea 1768:Formentera 1593:the first 1541:centimetre 1537:CGS system 1348:Talleyrand 1008:See also: 928:Talleyrand 677:Gravimetry 626:flattening 606:Gravimeter 358:Copernicus 328:Paris feet 307:Roman mile 287:Roman foot 268:Roman foot 181:krypton-86 167:by thirty 103:flattening 35:North Pole 9667:118871648 9453:14 August 9333:Perot, A. 9277:7 October 9224:7 October 9160:1476-4687 8880:17 August 8807:0003-3804 8689:120943411 8681:1432-1394 8612:30 August 8328:121338356 8320:0031-9228 8273:0004-6302 8214:0004-6337 8127:29 August 8089:31 August 8062:29 August 7976:15 August 7893:cite book 7863:cite book 7799:125925505 7791:0949-7714 7744:125240402 7736:1521-3889 7646:198204435 7638:1432-1394 7543:27 August 7512:0398-7817 7481:0252-9211 7434:cite book 7403:cite book 7302:1 October 7277:1 October 7150:30 August 7125:119447198 7117:1432-1394 7095:CiteSeerX 7032:cite book 7002:cite book 6960:0004-6337 6938:(7): 97. 6907:CiteSeerX 6879:cite book 6847:cite book 6796:cite book 6788:861693071 6734:7 October 6708:7 October 6568:0096-3771 6503:cite book 6477:126724939 6469:1631-0705 6415:6 October 6390:6 October 6321:109333769 6260:cite book 6132:143514819 6124:0035-9149 5960:6 October 5929:cite book 5901:6 October 5878:0004-6302 5797:109333769 5789:0261-0523 5753:0261-0523 5676:0035-9149 5608:1631-0705 5507:31 August 5445:31 August 5322:0004-6337 5277:CiteSeerX 5252:30 August 5221:cite book 5149:0398-7817 5050:1298-9800 4970:0398-7817 4800:894499177 4598:894499177 4541:300706536 4443:cite book 4435:894499177 4402:758713673 4016: μm. 3978:compared. 3967:Barcelona 3931:2°10′01″E 3887:2°34′24″E 3846:2°22′34″E 3796:; 1 3778:; 1 3758:. 1 3692:π 3688:⋅ 3685:ℓ 3592:π 3558:ℓ 3493:ℓ 3487:π 3289:0.05–0.01 3099:microwave 3023:traceable 2921:in 1907. 2835:Euclidean 2762:metrology 2580:physicist 2486:in 1875, 2448:Neuchâtel 2430:(German: 2384:metrology 2310:expansion 2302:standards 2219:metrology 2166:work. 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