Hauts-de-Seine is a department of France. It is part of the Métropole du Grand Paris and of the Île-de-France region, covers the western inner suburbs of Paris, it is small and densely populated and contains the modern office and shopping complex known as La Défense. Hauts-de-Seine and two other small départements, Seine-Saint-Denis and Val-de-Marne, form a ring around Paris, known as the Petite Couronne and are together with the City of Paris included in the Greater Paris since 1 January 2016. Hauts-de-Seine is made up of three departmental arrondissements and 36 communes: Hauts-de-Seine has a general council of which members are called general councillors; the general council is the deliberative organ of the department. The general councilors are elected by the inhabitants of the departement for a 6-years term; the general council is ruled by a president. See Hauts-de-Seine General Council; the Hauts-de-Seine department was created in 1968, from parts of the former départements of Seine and Seine-et-Oise.
Its creation reflected the implementation of a law passed in 1964, Nanterre had been selected as the prefecture for the new department early in 1965. In the 1990s and early 2000s, Hauts-de-Seine received national attention as the result of a corruption scandal concerning the misuse of public funds provided for the department's housing projects. Implicated were former minister and former president of the Hauts-de-Seine General Council, Charles Pasqua, other personalities of the RPR party. Hauts-de-Seine is one of Europe's richest areas, its GDP per capita was US$119,778 in 2015, according to INSEE official figures. Hauts-de-Seine was the political base of Nicolas Sarkozy, President of the Republic from 2007 to 2012, he was the mayor of Neuilly-sur-Seine in the department. Charles Pasqua was based in Hauts-de-Seine. Website of the General council Prefecture website
Acoustics is the branch of physics that deals with the study of all mechanical waves in gases and solids including topics such as vibration, sound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical engineer; the application of acoustics is present in all aspects of modern society with the most obvious being the audio and noise control industries. Hearing is one of the most crucial means of survival in the animal world, speech is one of the most distinctive characteristics of human development and culture. Accordingly, the science of acoustics spreads across many facets of human society—music, architecture, industrial production and more. Animal species such as songbirds and frogs use sound and hearing as a key element of mating rituals or marking territories. Art, craft and technology have provoked one another to advance the whole, as in many other fields of knowledge. Robert Bruce Lindsay's'Wheel of Acoustics' is a well accepted overview of the various fields in acoustics.
The word "acoustic" is derived from the Greek word ἀκουστικός, meaning "of or for hearing, ready to hear" and that from ἀκουστός, "heard, audible", which in turn derives from the verb ἀκούω, "I hear". The Latin synonym is "sonic", after which the term sonics used to be a synonym for acoustics and a branch of acoustics. Frequencies above and below the audible range are called "ultrasonic" and "infrasonic", respectively. In the 6th century BC, the ancient Greek philosopher Pythagoras wanted to know why some combinations of musical sounds seemed more beautiful than others, he found answers in terms of numerical ratios representing the harmonic overtone series on a string, he is reputed to have observed that when the lengths of vibrating strings are expressible as ratios of integers, the tones produced will be harmonious, the smaller the integers the more harmonious the sounds. If, for example, a string of a certain length would sound harmonious with a string of twice the length. In modern parlance, if a string sounds the note C when plucked, a string twice as long will sound a C an octave lower.
In one system of musical tuning, the tones in between are given by 16:9 for D, 8:5 for E, 3:2 for F, 4:3 for G, 6:5 for A, 16:15 for B, in ascending order. Aristotle understood that sound consisted of compressions and rarefactions of air which "falls upon and strikes the air, next to it...", a good expression of the nature of wave motion. In about 20 BC, the Roman architect and engineer Vitruvius wrote a treatise on the acoustic properties of theaters including discussion of interference and reverberation—the beginnings of architectural acoustics. In Book V of his De architectura Vitruvius describes sound as a wave comparable to a water wave extended to three dimensions, when interrupted by obstructions, would flow back and break up following waves, he described the ascending seats in ancient theaters as designed to prevent this deterioration of sound and recommended bronze vessels of appropriate sizes be placed in theaters to resonate with the fourth, fifth and so on, up to the double octave, in order to resonate with the more desirable, harmonious notes.
During the Islamic golden age, Abū Rayhān al-Bīrūnī is believed to postulated that the speed of sound was much slower than the speed of light. The physical understanding of acoustical processes advanced during and after the Scientific Revolution. Galileo Galilei but Marin Mersenne, discovered the complete laws of vibrating strings. Galileo wrote "Waves are produced by the vibrations of a sonorous body, which spread through the air, bringing to the tympanum of the ear a stimulus which the mind interprets as sound", a remarkable statement that points to the beginnings of physiological and psychological acoustics. Experimental measurements of the speed of sound in air were carried out between 1630 and 1680 by a number of investigators, prominently Mersenne. Meanwhile, Newton derived the relationship for wave velocity in solids, a cornerstone of physical acoustics; the eighteenth century saw major advances in acoustics as mathematicians applied the new techniques of calculus to elaborate theories of sound wave propagation.
In the nineteenth century the major figures of mathematical acoustics were Helmholtz in Germany, who consolidated the field of physiological acoustics, Lord Rayleigh in England, who combined the previous knowledge with his own copious contributions to the field in his monumental work The Theory of Sound. In the 19th century, Wheatstone and Henry developed the analogy between electricity and acoustics; the twentieth century saw a burgeoning of technological applications of the large body of scientific knowledge, by in place. The first such application was Sabine’s groundbreaking work in architectural acoustics, many others followed. Underwater acoustics was used for detecting submarines in the first World War. Sound recording and the telephone played important roles in a global transformation of society. Sound measurement and analysis reached new levels of accuracy and sophistication through the use of electronics and computing; the ultrasonic frequency range enabled wholly new kinds of application in industry.
New kinds of transducers were put to use. Acoustics is defined by ANSI/
National Institute of Standards and Technology
The National Institute of Standards and Technology is a physical sciences laboratory, a non-regulatory agency of the United States Department of Commerce. Its mission is to promote industrial competitiveness. NIST's activities are organized into laboratory programs that include nanoscale science and technology, information technology, neutron research, material measurement, physical measurement; the American AI initiative has called NIST to lead the development of appropriate technical standards for reliable, trustworthy, secure and interoperable AI systems. The Articles of Confederation, ratified by the colonies in 1781, contained the clause, "The United States in Congress assembled shall have the sole and exclusive right and power of regulating the alloy and value of coin struck by their own authority, or by that of the respective states—fixing the standards of weights and measures throughout the United States". Article 1, section 8, of the Constitution of the United States, transferred this power to Congress.
To coin money, regulate the value thereof, of foreign coin, fix the standard of weights and measures". In January 1790, President George Washington, in his first annual message to Congress stated that, "Uniformity in the currency and measures of the United States is an object of great importance, will, I am persuaded, be duly attended to", ordered Secretary of State Thomas Jefferson to prepare a plan for Establishing Uniformity in the Coinage and Measures of the United States, afterwards referred to as the Jefferson report. On October 25, 1791, Washington appealed a third time to Congress, "A uniformity of the weights and measures of the country is among the important objects submitted to you by the Constitution and if it can be derived from a standard at once invariable and universal, must be no less honorable to the public council than conducive to the public convenience", but it was not until 1838, that a uniform set of standards was worked out. In 1821, John Quincy Adams had declared "Weights and measures may be ranked among the necessities of life to every individual of human society".
From 1830 until 1901, the role of overseeing weights and measures was carried out by the Office of Standard Weights and Measures, part of the United States Department of the Treasury. In 1901, in response to a bill proposed by Congressman James H. Southard, the National Bureau of Standards was founded with the mandate to provide standard weights and measures, to serve as the national physical laboratory for the United States. President Theodore Roosevelt appointed Samuel W. Stratton as the first director; the budget for the first year of operation was $40,000. The Bureau took custody of the copies of the kilogram and meter bars that were the standards for US measures, set up a program to provide metrology services for United States scientific and commercial users. A laboratory site was constructed in Washington, DC, instruments were acquired from the national physical laboratories of Europe. In addition to weights and measures, the Bureau developed instruments for electrical units and for measurement of light.
In 1905 a meeting was called that would be the first "National Conference on Weights and Measures". Conceived as purely a metrology agency, the Bureau of Standards was directed by Herbert Hoover to set up divisions to develop commercial standards for materials and products.page 133 Some of these standards were for products intended for government use, but product standards affected private-sector consumption. Quality standards were developed for products including some types of clothing, automobile brake systems and headlamps and electrical safety. During World War I, the Bureau worked on multiple problems related to war production operating its own facility to produce optical glass when European supplies were cut off. Between the wars, Harry Diamond of the Bureau developed a blind approach radio aircraft landing system. During World War II, military research and development was carried out, including development of radio propagation forecast methods, the proximity fuze and the standardized airframe used for Project Pigeon, shortly afterwards the autonomously radar-guided Bat anti-ship guided bomb and the Kingfisher family of torpedo-carrying missiles.
In 1948, financed by the United States Air Force, the Bureau began design and construction of SEAC, the Standards Eastern Automatic Computer. The computer went into operation in May 1950 using a combination of vacuum tubes and solid-state diode logic. About the same time the Standards Western Automatic Computer, was built at the Los Angeles office of the NBS by Harry Huskey and used for research there. A mobile version, DYSEAC, was built for the Signal Corps in 1954. Due to a changing mission, the "National Bureau of Standards" became the "National Institute of Standards and Technology" in 1988. Following September 11, 2001, NIST conducted the official investigation into the collapse of the World Trade Center buildings. NIST, known between 1901 and 1988 as the National Bureau of Standards, is a measurement standards laboratory known as a National Metrological Institute, a non-regulatory agency of the United States Department of Commerce; the institute's official mission is to: Promote U. S. innovation and industrial competitiveness by advancing measurement science and technology in ways that enhance economic security and improve our quality of life.
NIST had an operating budget for fiscal year 2007 of about $843.3 million. NIST's 2009 budget was $992 million
France the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, from the Rhine to the Atlantic Ocean, it is bordered by Belgium and Germany to the northeast and Italy to the east, Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic and Indian oceans; the country's 18 integral regions span a combined area of 643,801 square kilometres and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Toulouse, Bordeaux and Nice. During the Iron Age, what is now metropolitan France was inhabited by a Celtic people. Rome annexed the area in 51 BC, holding it until the arrival of Germanic Franks in 476, who formed the Kingdom of Francia.
The Treaty of Verdun of 843 partitioned Francia into Middle Francia and West Francia. West Francia which became the Kingdom of France in 987 emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War. During the Renaissance, French culture flourished and a global colonial empire was established, which by the 20th century would become the second largest in the world; the 16th century was dominated by religious civil wars between Protestants. France became Europe's dominant cultural and military power in the 17th century under Louis XIV. In the late 18th century, the French Revolution overthrew the absolute monarchy, established one of modern history's earliest republics, saw the drafting of the Declaration of the Rights of Man and of the Citizen, which expresses the nation's ideals to this day. In the 19th century, Napoleon established the First French Empire, his subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a tumultuous succession of governments culminating with the establishment of the French Third Republic in 1870.
France was a major participant in World War I, from which it emerged victorious, was one of the Allies in World War II, but came under occupation by the Axis powers in 1940. Following liberation in 1944, a Fourth Republic was established and dissolved in the course of the Algerian War; the Fifth Republic, led by Charles de Gaulle, remains today. Algeria and nearly all the other colonies became independent in the 1960s and retained close economic and military connections with France. France has long been a global centre of art and philosophy, it hosts the world's fourth-largest number of UNESCO World Heritage Sites and is the leading tourist destination, receiving around 83 million foreign visitors annually. France is a developed country with the world's sixth-largest economy by nominal GDP, tenth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, human development.
France is considered a great power in global affairs, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a leading member state of the European Union and the Eurozone, a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, La Francophonie. Applied to the whole Frankish Empire, the name "France" comes from the Latin "Francia", or "country of the Franks". Modern France is still named today "Francia" in Italian and Spanish, "Frankreich" in German and "Frankrijk" in Dutch, all of which have more or less the same historical meaning. There are various theories as to the origin of the name Frank. Following the precedents of Edward Gibbon and Jacob Grimm, the name of the Franks has been linked with the word frank in English, it has been suggested that the meaning of "free" was adopted because, after the conquest of Gaul, only Franks were free of taxation.
Another theory is that it is derived from the Proto-Germanic word frankon, which translates as javelin or lance as the throwing axe of the Franks was known as a francisca. However, it has been determined that these weapons were named because of their use by the Franks, not the other way around; the oldest traces of human life in what is now France date from 1.8 million years ago. Over the ensuing millennia, Humans were confronted by a harsh and variable climate, marked by several glacial eras. Early hominids led a nomadic hunter-gatherer life. France has a large number of decorated caves from the upper Palaeolithic era, including one of the most famous and best preserved, Lascaux. At the end of the last glacial period, the climate became milder. After strong demographic and agricultural development between the 4th and 3rd millennia, metallurgy appeared at the end of the 3rd millennium working gold and bronze, iron. France has numerous megalithic sites from the Neolithic period, including the exceptiona
National Physical Laboratory (United Kingdom)
The National Physical Laboratory is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington, England. It comes under the management of the Department for Business and Industrial Strategy; the National Physical Laboratory was established in 1900 at Bushy House "to bring scientific knowledge to bear upon our everyday industrial and commercial life". It grew to fill a large selection of buildings on the Teddington site. NPL procured a large state-of-the-art laboratory under a Private Finance Initiative contract in 1998; the construction, being undertaken by John Laing, the maintenance of this new building, being undertaken by Serco, was transferred back to the DTI in 2004 after the private sector companies involved made losses of over £100m. The laboratory was run by the UK government, with members of staff being part of the civil service. Administration of the NPL was contracted out in 1995 under a Government Owned Contractor Operated model, with Serco winning the bid and all staff transferred to their employ.
Under this regime, overhead costs halved, third party revenues grew by 16% per annum, the number of peer-reviewed research papers published doubled. It was decided in 2012 to change the operating model for NPL from 2014 onward to include academic partners and to establish a postgraduate teaching institute on site; the date of the changeover was postponed for up to a year. The candidates for lead academic partner were the Universities of Edinburgh, Southampton and Surrey with an alliance of the Universities of Strathclyde and Surrey chosen as preferred partners. In January 2013 funding for a new £25m Advanced Metrology Laboratory was announced that will be built on the footprint of an existing unused building; the operation of the laboratory transferred back to the Department for Business and Skills ownership on 1 January 2015. The National Physical Laboratory is involved with new developments in metrology, such as researching metrology for, standardising, nanotechnology, it is based at the Teddington site, but has a site in Huddersfield for dimensional metrology and an underwater acoustics facility at Wraysbury Reservoir.
Notable researchers at NPL Researchers who have worked at NPL include: D. W. Dye who did important work in developing the technology of quartz clocks; the inventor Sir Barnes Wallis did early development work there on the "Bouncing Bomb" used in the "Dam Busters" wartime raids. H. J. Gough, one of the pioneers of research into metal fatigue, worked at NPL for 19 years from 1914 to 1938. Sydney Goldstein and Sir James Lighthill worked in NPL's aerodynamics division during World War II researching boundary layer theory and supersonic aerodynamics respectively. Dr Clifford Hodge worked there and was engaged in research on semiconductors. Others who have spent time at NPL include Robert Watson-Watt considered the inventor of radar, Oswald Kubaschewski, the father of computational materials thermodynamics and the numerical analyst James Wilkinson. NPL research has contributed to physical science, materials science and bioscience. Applications have been found in ship design, aircraft development, computer networking and global positioning.
The first accurate atomic clock, a caesium standard based on a certain transition of the caesium-133 atom, was built by Louis Essen and Jack Parry in 1955 at NPL. Calibration of the caesium standard atomic clock was carried out by the use of the astronomical time scale ephemeris time; this led to the internationally agreed definition of the latest SI second being based on atomic time. NPL has undertaken computer research since the mid-1940s. From 1945, Alan Turing led the design of the Automatic Computing Engine computer; the ACE project was floundered, leading to Turing's departure. Donald Davies took the project over and concentrated on delivering the less ambitious Pilot ACE computer, which first worked in May 1950. Among those who worked on the project was American computer pioneer Harry Huskey. A commercial spin-off, DEUCE was manufactured by English Electric Computers and became one of the best-selling machines of the 1950s. Beginning in the mid-1960s, Donald Davies and his team at the NPL pioneered packet switching, now the dominant basis for data communications in computer networks worldwide.
Davies designed and proposed a national data network based on packet switching in his 1965 Proposal for the Development of a National Communications Service for On-line Data Processing. Subsequently, the NPL team developed the concept into a local area network which operated from 1969 to 1986, carried out work to analyse and simulate the performance of packet switching networks, their research and practice influenced the ARPANET in the United States, the forerunner of the Internet, other researchers in the UK and Europe. Directors of NPL Directors of NPL include a number of notable individuals. Sir Richard Tetley Glazebrook, 1900–1919 Sir Joseph Ernest Petavel, 1919–1936 Sir Frank Edward Smith, 1936–1937 Lawrence Bragg, 1937–1938 Sir Charles Galton Darwin, 1938–1949 Sir Edward Victor Appleton, 1941 Sir Edward Crisp Bullard, 1948–1955 Dr Reginald Leslie Smith-Rose, 1955–1956 Sir Gordon Brims Black McIvor Sutherland, 1956–1964 Dr John Vernon Dunworth, 1964–1977 Dr Paul Dean, 1977–1990 Dr Peter Clapham, 1990–1995Managing Directors Dr John Rae, 1995–2000 Dr Bob McGuiness, 2000–2005 Steve McQuillan, 2005–2008 Dr Martyn Sené, 2008–2009, 2015 Dr Brian Bowsher, 2009–2015Chief Executive Officers Dr Peter Thompson, 2015–presentN
Unit of measurement
A unit of measurement is a definite magnitude of a quantity and adopted by convention or by law, used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement. For example, a length is a physical quantity; the metre is a unit of length. When we say 10 metres, we mean 10 times the definite predetermined length called "metre". Measurement is a process of determining how large or small a physical quantity is as compared to a basic reference quantity of the same kind; the definition and practical use of units of measurement have played a crucial role in human endeavour from early ages up to the present. A multitude of systems of units used to be common. Now there is a global standard, the International System of Units, the modern form of the metric system. In trade and measures is a subject of governmental regulation, to ensure fairness and transparency; the International Bureau of Weights and Measures is tasked with ensuring worldwide uniformity of measurements and their traceability to the International System of Units.
Metrology internationally accepted units of measurement. In physics and metrology, units are standards for measurement of physical quantities that need clear definitions to be useful. Reproducibility of experimental results is central to the scientific method. A standard system of units facilitates this. Scientific systems of units are a refinement of the concept of weights and measures developed for commercial purposes. Science and engineering use larger and smaller units of measurement than those used in everyday life; the judicious selection of the units of measurement can aid researchers in problem solving. In the social sciences, there are no standard units of measurement and the theory and practice of measurement is studied in psychometrics and the theory of conjoint measurement. A unit of measurement is a standardised quantity of a physical property, used as a factor to express occurring quantities of that property. Units of measurement were among the earliest tools invented by humans. Primitive societies needed rudimentary measures for many tasks: constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials.
The earliest known uniform systems of measurement seem to have all been created sometime in the 4th and 3rd millennia BC among the ancient peoples of Mesopotamia and the Indus Valley, also Elam in Persia as well. Weights and measures are mentioned in the Bible, it is a commandment to have fair measures. In the Magna Carta of 1215 with the seal of King John, put before him by the Barons of England, King John agreed in Clause 35 "There shall be one measure of wine throughout our whole realm, one measure of ale and one measure of corn—namely, the London quart; as of the 21st Century, multiple unit systems are used all over the world such as the United States Customary System, the British Customary System, the International System. However, the United States is the only industrialized country that has not yet converted to the Metric System; the systematic effort to develop a universally acceptable system of units dates back to 1790 when the French National Assembly charged the French Academy of Sciences to come up such a unit system.
This system was the precursor to the metric system, developed in France but did not take on universal acceptance until 1875 when The Metric Convention Treaty was signed by 17 nations. After this treaty was signed, a General Conference of Weights and Measures was established; the CGPM produced the current SI system, adopted in 1954 at the 10th conference of weights and measures. The United States is a dual-system society which uses both the SI system and the US Customary system; the use of a single unit of measurement for some quantity has obvious drawbacks. For example, it is impractical to use the same unit for the distance between two cities and the length of a needle, thus they would develop independently. One way to make large numbers or small fractions easier to read, is to use unit prefixes. At some point in time though, the need to relate the two units might arise, the need to choose one unit as defining the other or viceversa. For example an inch could be defined in terms of a barleycorn.
A system of measurement is a collection of units of measurement and rules relating them to each other. As science progressed, a need arose to relate the measurement systems of different quantities, like length and weight and volume; the effort of attempting to relate different traditional systems between each other exposed many inconsistencies, brought about the development of new units and systems. Systems of measurement in modern use include the metric system, the imperial system, United States customary units. Many of the systems of measurement, in use were to some extent based on the dimensions of the human body; as a result, units of measure could vary not only from location to location, but from person to person. Metric systems of units have evolved since the adoption of the original metric system in France in 1791; the current international standard metric system is the International System of Units. An important feature of modern systems is standardization; each unit has a universally recognized size.
Both the imperial units and US customary
History of the metre
The history of the metre starts with the scientific revolution that began with Nicolaus Copernicus's work in 1543. Accurate measurements were required, 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 in use, they preferred a decimal system to ease their calculations. With the French Revolution came a desire to replace many features of the Ancien Régime, including the traditional units of measure; as a base unit of length, many scientists favored the seconds pendulum, but this was rejected when it was discovered that it varied from place to place with local gravity. A new unit of length, the metre was introduced - defined as one ten-millionth of the distance from the North Pole to the equator. For practical purposes however, the standard metre was made available in the form of a platinum bar held in Paris; this in turn was replaced in 1889 by thirty platinum-iridium bars kept across the globe.
However, using such physical objects as the standard had been something that the original definition had aimed to avoid, so in 1960 a new definition based on a specific number of wavelengths of light from a specific transition in krypton-86 allowed the standard to be universally available by measurement. In 1983 this was updated to the current definition: "the length of the path travelled by light in a vacuum in 1/299,792,458 of a second"During the mid nineteenth century the metre gained adoption worldwide in scientific usage, was established as an international measurement unit by the Metre Convention of 1875. Where older traditional length measures are still used, they are now defined in terms of the metre - for example the yard has since 1959 been defined as 0.9144 metre. The standard measures of length in Europe diverged from one another after the fall of the Carolingian Empire: while measures could be standardized within a given jurisdiction, there were numerous variations of measure between regions.
Indeed, as the measures were used as the basis for taxation, the use of a particular measure was associated with the sovereignty of a given ruler and dictated by law. With the increasing scientific activity of the 17th century came calls for the institution of a "universal measure" or "metro cattolico", which would be based on natural phenomena rather than royal decree, would be decimal rather than using the various systems of subdivision duodecimal, which coexisted at the time. According to Wilkins it was Christopher Wren's idea to choose the length of a "seconds pendulum" as the unit of length: such pendulums had been demonstrated by Christiaan Huygens, their length is quite close to one modern metre. However, it was soon discovered that the length of a seconds pendulum varies from place to place: French astronomer Jean Richer had measured the 0.3% difference in length between Cayenne and Paris. Jean Richer and Giovanni Domenico Cassini measured the parallax of Mars between Paris and Cayenne in French Guiana when Mars was at its closest to Earth in 1672.
They arrived at a figure for the solar parallax of 91/2 inches, equivalent to an Earth–Sun distance of about 22,000 Earth radii. They were the first astronomers to have access to an accurate and reliable value for the radius of Earth, measured by their colleague Jean Picard in 1669 as 3269 thousand toises. Isaac Newton used this measurement for establishing his law of universal gravitation. 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; the determination of the figure of the earth became a problem of the highest importance in astronomy, inasmuch as the diameter of the earth was the unit to which all celestial distances had to be referred. Geodetic surveys found practical applications in French cartography and in the Anglo-French Survey, which aimed to connect Paris and Greenwich Observatories and led to the Principal Triangulation of Great Britain.
The unit of length used by the French was the Toise de Paris, divided in six feet. The English unit of length was the yard; the French main unit of length was the Toise of Paris whose standard was the Toise of Châtelet, fixed outside the Grand Châtelet in Paris from 1668 to 1776. In 1735 two geodetic standards were calibrated against the Toise of Châtelet. One of them, the Toise of Peru was used for the Spanish-French Geodesic Mission. In 1766 the Toise of Peru became the official standard of the Toise in France and was renamed as the Toise of the Academy. Despite scientific progresses in the field of geodesy, little practical advance was made towards the establishment of the "universal measure" until the French Revolution of 1789. France was affected by the proliferation of length measures, the need for reform was accepted across all political viewpoints if it needed the push of revolution to bring it about. Talleyrand 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