# Category:18th-century French mathematicians

## Pages in category "18th-century French mathematicians"

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## Pages in category "18th-century French mathematicians"

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The following 75 pages are in this category, out of 75 total, this list may not reflect recent changes (learn more).

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1. Jean le Rond d'Alembert – Jean-Baptiste le Rond dAlembert was a French mathematician, mechanician, physicist, philosopher, and music theorist. Until 1759 he was also co-editor with Denis Diderot of the Encyclopédie, DAlemberts formula for obtaining solutions to the wave equation is named after him. The wave equation is referred to as dAlemberts equation. Born in Paris, dAlembert was the son of the writer Claudine Guérin de Tencin and the chevalier Louis-Camus Destouches. Destouches was abroad at the time of dAlemberts birth, days after birth his mother left him on the steps of the Saint-Jean-le-Rond de Paris church. According to custom, he was named after the saint of the church. DAlembert was placed in an orphanage for foundling children, but his father found him and placed him with the wife of a glazier, Madame Rousseau, Destouches secretly paid for the education of Jean le Rond, but did not want his paternity officially recognized. DAlembert first attended a private school, the chevalier Destouches left dAlembert an annuity of 1200 livres on his death in 1726. Under the influence of the Destouches family, at the age of twelve entered the Jansenist Collège des Quatre-Nations. Here he studied philosophy, law, and the arts, graduating as baccalauréat en arts in 1735, in his later life, DAlembert scorned the Cartesian principles he had been taught by the Jansenists, physical promotion, innate ideas and the vortices. The Jansenists steered DAlembert toward a career, attempting to deter him from pursuits such as poetry. Theology was, however, rather unsubstantial fodder for dAlembert and he entered law school for two years, and was nominated avocat in 1738. He was also interested in medicine and mathematics, Jean was first registered under the name Daremberg, but later changed it to dAlembert. The name dAlembert was proposed by Johann Heinrich Lambert for a moon of Venus. In July 1739 he made his first contribution to the field of mathematics, at the time Lanalyse démontrée was a standard work, which dAlembert himself had used to study the foundations of mathematics. DAlembert was also a Latin scholar of note and worked in the latter part of his life on a superb translation of Tacitus. In 1740, he submitted his second scientific work from the field of fluid mechanics Mémoire sur la réfraction des corps solides, in this work dAlembert theoretically explained refraction. In 1741, after failed attempts, dAlembert was elected into the Académie des Sciences

2. Jacques d'Allonville – Jacques Eugène dAllonville de Louville was born on July 14,1671 at the Louville Castle in Beauce France. Jacques died on September 10,1732 at the age of 61 and he was an astronomer and mathematician. He also went by the name of Chevalier de Louville, louvilles father was the lord of Louville. His mother was born a Vaultier de Moyencourt and his older Brother named Charles Auguste was known for his role with Philippe V of Spain and was a member of the family who had a higher social rank. • At the age of 12, Les Elements d Euclid translated by Dennis Henrion fell into his hands and he read it without a guide and this lecture was a marking point for him in his life. Louville was the youngest in the Royal Navy and he fought in the Battle of Hougue in 1692. He became army captain at the end of 1700 and his older brother Charles Auguste who served with the duke of Anjou of Spain, brought him there. He was nominated to be a brigadier and his services were recognized with a pension, when he returned to France, he resumed his service. He became a prisoner of war in 1708 at the battle of Oudenarde and he wasnt set free for two years. Once he was released he became Colonel of the Dragons of The Queen army and was paid by the king and he later found peace in returning to the study of astronomy. He cut the ties with the army and against the wishes of his family, he returned his officer certificate and he devoted his time to mathematics and the principle of astronomy. Louville went to Marseille in 1713 or 1714, to measure the height of the pole needed to tie his observations of the stars to the observations of Pythéas. In 1715 Louville went to London to observe a solar eclipse assisting Edmond Halley in the remarkable phenomenon. The men saw on the surface of the moon jets of light that lasted for an instant. In 1717 he situated himself in Carré a mile from Orléans and he had been a member of the Academy of Sciences since 1714 and the Academy had a residency obligation. The situation was not a regular occurrence, but Louville promised to communicate to the school annually, kept his promise and continued to study the sky in Oréans. Fontenelle who did not fail to make the connection with the child refusing the tonsure, was an independent minded man, nor misanthrope, nor austere, but generous with his time. If one arrived early for dinner he did not mind, he read a book from his library or he would take a walk

3. Jean-Baptiste Biot – Jean-Baptiste Biot was a French physicist, astronomer, and mathematician who established the reality of meteorites, made an early balloon flight, and studied the polarization of light. The mineral biotite was named in his honor, Jean-Baptiste Biot was born in Paris on 21 April 1774 the son of Joseph Biot, a treasury official. He was educated at Lyceum Louis-le-Grand and École Polytechnique in 1794, Biot served in the artillery before he was appointed professor of mathematics at Beauvais in 1797. He later went on to become a professor of physics at the Collège de France around 1800, in 1804 Biot was on board for the first scientific hot-air balloon ride with Gay-Lussac. They reached a height of 7016 metres, quite dangerous without supplementary oxygen, Biot was also a member of the Legion of Honor, he was elected chevalier in 1814 and commander in 1849. In addition, Biot received the Rumford Medal in 1840, awarded by the Royal Society in the field of thermal or optical properties of matter. In 1850 Jean-Baptiste Biot published in the Journal des savants a 7-page memoir from his recollections of the period of the late 1790s, Jean-Baptiste Biot had a single son, Édouard Constant Biot, an engineer and Sinologist, born in 1803. Edouard died in 1850 and it was thanks to the extraordinary efforts of his father that the second half of Edouards last book. It had been left in manuscript, unfinished, to this day, Biots translation remains the only translation into a Western language of this book. He died in Paris on 3 February 1862, Jean-Baptiste Biot made many contributions to the scientific community in his lifetime – most notably in optics, magnetism, and astronomy. The Biot–Savart law in magnetism is named after Biot and his colleague Félix Savart for their work in 1820, in 1803 Biot was sent by the Académie française to report back on 3000 meteorites that fell on L’aigle, France. He found that the meteorites, called stones at the time, were from outer space, with his report, Biot helped support Ernst Florens Friedrich Chladnis argument that meteorites were debris from space, which he had published in 1794. Prior to Biots thorough investigation of the meteorites that fell near lAigle, France in 1803, there were anecdotal tales of unusual rocks found on the ground after fireballs had been seen in the sky, but such stories were often dismissed as fantasy. Serious debate concerning the unusual rocks began in 1794 when German physicist Chladni published a book claiming that rocks had an extraterrestrial origin. Only after Biot was able to analyze the rocks at lAigle was it accepted that the fireballs seen in the sky were meteors falling through the atmosphere. Since Biots time, analysis of meteorites has resulted in measurements of the chemical composition of the solar system. The composition and position of meteors in the system have also given astronomers clues as to how the solar system formed. In 1812, Biot turned his attention to the study of optics, prior to the 19th century, light was believed to consist of discrete packets called corpuscles

4. Jean-Charles de Borda – Jean-Charles, chevalier de Borda was a French mathematician, physicist, political scientist, and sailor. Borda was born in the city of Dax to Jean‐Antoine de Borda, in 1756, Borda wrote Mémoire sur le mouvement des projectiles, a product of his work as a military engineer. For that, he was elected to the French Academy of Sciences in 1764, Borda was a mariner and a scientist, spending time in the Caribbean testing out advances in chronometers. Between 1777 and 1778, he participated in the American Revolutionary War, in 1781, he was put in charge of several vessels in the French Navy. In 1782, he was captured by the English, and was returned to France shortly after and he returned as an engineer in the French Navy, making improvements to waterwheels and pumps. In 1770, Borda formulated a ranked voting system that is referred to as the Borda count. The Borda count is in use today in some institutions, competitions. The Borda count has also served as a basis for other such as the Quota Borda system. Another of his contributions is his construction of the standard metre, as an instrument maker, he improved the reflecting circle and the repeating circle, the latter used to measure the meridian arc from Dunkirk to Barcelona by Delambre and Méchain. This required the calculation of trigonometric tables and logarithms corresponding to the new size of the degree, the tables of logarithms of sines, secants, and tangents were also required for the purposes of navigation. The division of the degree into hundredths was accompanied by the division of the day into 10 hours of 100 minutes, the Republican Calendar was abolished by Napoleon in 1806, but the 400-degree circle lived on as the Gradian. Five French ships were named Borda in his honour, the crater Borda on the Moon is named after him. Asteroide 175726 has been called Borda in his honour and his name is one of the 72 names inscribed on the Eiffel Tower. Cape Borda on the northwest coast of Kangaroo Island in South Australia is named in his honour, Île Borda was the name given to Kangaroo Island in his honour by Nicholas Baudin. Borda–Carnot equation OConnor, John J. Robertson, Edmund F, jean Charles de Borda, MacTutor History of Mathematics archive, University of St Andrews

5. Charles Bossut – Charles Bossut was a French mathematician and confrère of the Encyclopaedists. He was born at Tartaras, Loire, and died in Paris,1768 member of Académie des sciences OConnor, John J. Robertson, Edmund F. Charles Bossut, MacTutor History of Mathematics archive, University of St Andrews. This article incorporates text from a now in the public domain, Wood, James. London and New York, Frederick Warne

6. Pierre Bouguer – Pierre Bouguer was a French mathematician, geophysicist, geodesist, and astronomer. He is also known as the father of naval architecture and his father, Jean Bouguer, one of the best hydrographers of his time, was regius professor of hydrography at Le Croisic in lower Brittany, and author of a treatise on navigation. He taught his sons Pierre and Jan at their home, where he taught private students. In 1714, at the age of 16, Pierre was appointed to succeed his father as professor of hydrography. These were published in the Prix de l’Academie des Sciences and he found the light of the sun to be 300 times more intense than that of the moon, and thus made some of the earliest measurements in photometry. In 1730 he was professor of hydrography at Havre. He also invented a heliometer, afterwards perfected by Joseph von Fraunhofer and he was afterwards promoted in the Academy to the place of Maupertuis, and went to reside in Paris. In 1735 Bouguer sailed with Charles Marie de La Condamine on a mission to Peru. Ten years were spent in this operation, an account of which was published by Bouguer in 1749. In 1746 he published the first treatise of naval architecture, Traité du navire and his later writings were nearly all upon the theory of navigation and naval architecture. In January,1750 he was elected a Fellow of the Royal Society, a crater on Mars was named in his honor. A lunar crater and an asteroid was named after him. His name is recalled as the meteorological term Bouguers halo which an observer may see infrequently in fog when sun breaks through. An infrequently observed meteorological phenomenon, a faint white, circular arc or complete ring of light that has a radius of 39 degrees and is centered on the antisolar point, when observed, it is usually in the form of a separate outer ring around an anticorona. The term Bouguer anomaly, referring to small variations in the Earths gravity field resulting from density variations in underlying rocks, is named after him. A large bronze statue of him stands at the port in Le Croisic, see The works of Jean Fréour List of geophysicists This article incorporates text from a publication now in the public domain, Chisholm, Hugh, ed. Bouguer, Pierre

7. Georges-Louis Leclerc, Comte de Buffon – Georges-Louis Leclerc, Comte de Buffon was a French naturalist, mathematician, cosmologist, and encyclopédiste. His works influenced the two generations of naturalists, including Jean-Baptiste Lamarck and Georges Cuvier. It has been said that Truly, Buffon was the father of all thought in natural history in the half of the 18th century. Buffon held the position of intendant at the Jardin du Roi, Georges was named after his mother’s uncle Georges Blaisot, the tax-farmer of the Duke of Savoy for all of Sicily. In 1714 Blaisot died childless, leaving a fortune to his seven-year-old godson. Benjamin Leclerc then purchased an estate containing the village of Buffon. Georges attended the Jesuit College of Godrans in Dijon from the age of ten onwards, from 1723–1726 he then studied law in Dijon, the prerequisite for continuing the family tradition in civil service. In 1728 Georges left Dijon to study mathematics and medicine at the University of Angers in France, in 1732 after the death of his mother and before the impending remarriage of his father, Georges left Kingston and returned to Dijon to secure his inheritance. Having added de Buffon to his name while traveling with the Duke, he repurchased the village of Buffon, with a fortune of about 80000 livres Buffon set himself up in Paris to pursue science, at first primarily mathematics and mechanics, and the increase of his fortune. In 1732 he moved to Paris, where he made the acquaintance of Voltaire, in 1734 he was admitted to the French Academy of Sciences. During this period he corresponded with the Swiss mathematician Gabriel Cramer and his protector Maurepas had asked the Academy of Sciences to do research on wood for the construction of ships in 1733. Soon afterward, Buffon began a study, performing some of the most comprehensive tests to date on the mechanical properties of wood. Included were a series of tests to compare the properties of small specimens with those of large members, in 1739 he was appointed head of the Parisian Jardin du Roi with the help of Maurepas, he held this position to the end of his life. Buffon was instrumental in transforming the Jardin du Roi into a research center. He also enlarged it, arranging the purchase of adjoining plots of land, thanks to his talent as a writer, he was invited to join Pariss second great academy, the Académie française in 1753. In his Discours sur le style, pronounced before the Académie française, he said, Writing well consists of thinking, feeling and expressing well, of clarity of mind, soul, the style is the man himself. Unfortunately for him, Buffons reputation as a literary stylist also gave ammunition to his detractors, The mathematician Jean le Rond DAlembert, for example, called him the great phrase-monger. In 1752 Buffon married Marie-Françoise de Saint-Belin-Malain, the daughter of an noble family from Burgundy

8. Jean-Pierre Christin – Jean-Pierre Christin was a French physicist, mathematician, astronomer and musician. His proposal to reverse the Celsius thermometer scale was accepted and is still in use today. He was a member of the Académie des sciences, belles-lettres et arts de Lyon. His thermometer was known in France before the Revolution as the thermometer of Lyon, one of these thermometers was kept at Science Museum in London. Mémoire sur lobservation dune éclipse de lune du 18 décembre, et sur quelques particularités relatives à ce phénomène, instrument propre aux opérations de géométrie pratique et dastronomie. Recherches sur les véritables dimensions du pied de roi et du pied de ville, lettre sur lusage de la jauge de Lyon. Parallèle des diverses méthodes de calcul pour mesurer le cercle, démonstration de divers problèmes de géométrie. Méthode pour tracer une méridienne par les hauteurs du soleil, observations sur les baromètres de différents genres. Fixation de la latitude ou élévation du pôle de Lyon, remarque sur la chaleur naturelle du corps humain, observée par le moyen du thermomètre de Lyon. Sur la chaleur directe du soleil, observée par le même instrument, Sur la chaleur des eaux minérales de Baréges. Expériences sur lincubation artificielle des œufs de poule, par le moyen de certains degrés de chaleur, expériences sur les aimants naturels et artificiels de diverses grandeurs. Joseph Jean Baptiste Xavier Fournet, Sur linvention du thermomètre centigrade à mercure, françois Casati, Le Thermomètre de Lyon. Lyon, Editions lyonnaises dart et dhistoire,1992, Académie de Sciencies, Belles-Lettres et Arts de Lyon

9. Alexis Clairaut – Alexis Claude Clairaut was a French mathematician, astronomer, and geophysicist. He was a prominent Newtonian whose work helped to establish the validity of the principles, Clairaut was one of the key figures in the expedition to Lapland that helped to confirm Newtons theory for the figure of the Earth. In that context, Clairaut worked out a mathematical result now known as Clairauts theorem and he also tackled the gravitational three-body problem, being the first to obtain a satisfactory result for the apsidal precession of the Moons orbit. In mathematics he is credited with Clairauts equation and Clairauts relation. Clairaut was born in Paris, France, to Jean-Babtiste and Catherine Petit Clairaut, the couple had 20 children, however only a few of them survived childbirth. Alexis was a prodigy — at the age of ten he began studying calculus, Clairaut was unmarried, and known for leading an active social life. Though he led a social life, he was very prominent in the advancement of learning in young mathematicians. He was elected a Fellow of the Royal Society of London in November,1737, Clairaut died in Paris in 1765. In 1736, together with Pierre Louis Maupertuis, he took part in the expedition to Lapland, the goal of the excursion was to geometrically calculate the shape of the Earth, which Sir Issac Newton theorized in his book Principia was an ellipsoid shape. They sought to prove if Newtons theory and calculations were correct or not, before the expedition team returned to Paris, Clairaut sent his calculations to the Royal Society of London. The writing was published by the society in the 1736-37 volume of Philosophical Transactions. Initially, Clairaut disagrees with Newtons theory on the shape of the Earth, in the article, he outlines several key problems that effectively disprove Newtons calculations, and provides some solutions to the complications. The issues addressed include calculating gravitational attraction, the rotation of an ellipsoid on its axis, and this conclusion suggests not only that the Earth is of an oblate ellipsoid shape, but it is flattened more at the poles and is wider at the center. His article in Philosophical Transactions created much controversy, as he addressed the problems of Newtons theory, after his return, he published his treatise Théorie de la figure de la terre. This proved Sir Issac Newtons theory that the shape of the Earth was an oblate ellipsoid, in 1849 Stokes showed that Clairauts result was true whatever the interior constitution or density of the Earth, provided the surface was a spheroid of equilibrium of small ellipticity. In 1741, Alexis Clairaut wrote a book called Èléments de Géométrie, the book outlines the basic concepts of geometry. Geometry in the 1700s was complex to the average learner and it was considered to be a dry subject. Clairaut saw this trend, and wrote the book in an attempt to make the more interesting for the average learner

10. Marquis de Condorcet – Unlike many of his contemporaries, he advocated a liberal economy, free and equal public instruction, constitutionalism, and equal rights for women and people of all races. His ideas and writings were said to embody the ideals of the Age of Enlightenment and rationalism and he died a mysterious death in prison after a period of flight from French Revolutionary authorities. Condorcet was born in Ribemont, and descended from the ancient family of Caritat, fatherless at a young age, he was raised by his devoutly religious mother. He was educated at the Jesuit College in Reims and at the Collège de Navarre in Paris, where he showed his intellectual ability. When he was sixteen, his analytical abilities gained the praise of Jean le Rond dAlembert and Alexis Clairaut, soon, from 1765 to 1774, he focused on science. In 1765, he published his first work on mathematics entitled Essai sur le calcul intégral and he would go on to publish more papers, and on 25 February 1769, he was elected to the Académie royale des Sciences. In 1772, he published another paper on integral calculus, soon after, he met Jacques Turgot, a French economist, and the two became friends. Turgot was to be an administrator under King Louis XV in 1772, Condorcet worked with Leonhard Euler and Benjamin Franklin. In 1774, Condorcet was appointed general of the Paris mint by Turgot. From this point on, Condorcet shifted his focus from the purely mathematical to philosophy, in the following years, he took up the defense of human rights in general, and of womens and Blacks rights in particular. He supported the ideals embodied by the newly formed United States, in 1776, Turgot was dismissed as Controller General. Consequently, Condorcet submitted his resignation as Inspector General of the Monnaie, but the request was refused, Condorcet later wrote Vie de M. Turgot, a biography which spoke fondly of Turgot and advocated Turgots economic theories. In 1785, Condorcet wrote an essay on the application of analysis of the probability of decisions made on a majority vote, the paper also outlines a generic Condorcet method, designed to simulate pair-wise elections between all candidates in an election. He disagreed strongly with the method of aggregating preferences put forth by Jean-Charles de Borda. Condorcet was one of the first to apply mathematics in the social sciences. In 1781, Condorcet wrote a pamphlet, Reflections on Negro Slavery, in 1786, Condorcet worked on ideas for the differential and integral calculus, giving a new treatment of infinitesimals – a work which was never printed. In 1789, he published Vie de Voltaire, which agreed with Voltaire in his opposition to the Church, in 1791, Condorcet along with Sophie de Grouchy, Thomas Paine, Etienne Dumont, Jacques-Pierre Brissot, and Achilles Duchastellet published a brief journal titled Le Républicain. Its main goal being the promotion of republicanism and the rejection of establishing a constitutional monarchy, the theme being that any sort of monarchy is a threat to freedom no matter who is leading, which emphasized that liberty is freedom from domination

11. Jean Baptiste Joseph Delambre – Jean Baptiste Joseph, chevalier Delambre was a French mathematician and astronomer. He was also director of the Paris Observatory, and author of books on the history of astronomy from ancient times to the 18th century. After a childhood fever, he suffered from very sensitive eyes, for fear of losing his ability to read, he devoured any book available and trained his memory. Delambres quickly achieved success in his career in astronomy, such that in 1788 and this portion of the meridian, which also passes through Paris, was to serve as the basis for the length of the quarter meridian, connecting the North Pole with the Equator. In April 1791, the academys Metric Commission confided this mission to Jean-Dominique de Cassini, Cassini was chosen to head the northern expedition but, as a royalist, he refused to serve under the revolutionary government after the arrest of King Louis XVI on his Flight to Varennes. Pierre Méchain headed the expedition, measuring from Barcelona to Rodez. The measurements were finished in 1798, the gathered data were presented to an international conference of savants in Paris the following year. After Méchains death in 1804, he was appointed director of the Paris Observatory and he was also professor of Astronomy at the Collège de France. The same year he married Elisabeth-Aglaée Leblanc de Pommard, a widow with whom he had lived already for a long time and he was a knight of the Order of Saint Michael and of the Légion dhonneur. His name is one of the 72 names inscribed on the Eiffel tower. He was elected a Foreign Honorary Member of the American Academy of Arts, Delambre died in 1822 and was interred in Père Lachaise Cemetery in Paris. The crater Delambre on the Moon is named after him,1, lxxii,556 pp.1 folded plate, vol. 2, viii,639 pp.16 folded plates, Reprinted by New York and London, Johnson Reprint Corporation,1965, with a new preface by Otto Neugebauer. Histoire de lastronomie du moyen age, Paris, Mme Ve Courcier,1819, lxxxiv,640 pp.17 folded plates. Reprinted by New York and London, Johnson Reprint Corporation,1965 OCLC647834, also reprinted by Paris, J. Gabay,2006. Histoire de lastronomie moderne, Paris, Mme Ve Courcier,1821,1, lxxxii,715 pp.9 folded plates, vol. 2,804 pp.8 folded plates, Reprinted by New York and London, Johnson Reprint Corporation,1969, with a new introduction and tables of contents by I. Also reprinted by Paris, Editions Jacques Gabay,2006 and this takes the history to the 17th century

12. Antoine Deparcieux – Antoine Deparcieux was a French mathematician. He was born at Clessous in the Portes, department of Gard and he attended the school of Saint Florent for 10 years while working on his family farm. In 1725, his desire for learning took him to Lyon, then, in 1730, he went to Paris to increase his knowledge of mathematics and physics. He made a living by manufacturing sundials, in 1746, he became a member of the Academy of Sciences, and in about 1765 was named Censeur Royal. He was also librarian at the University of Strasbourg, and member of the Academy of Sciences of Paris, Montpellier, Lyon, Amiens, Metz, Berlin, and Stockholm. Life annuity OConnor, John J. Robertson, Edmund F. Antoine Deparcieux, MacTutor History of Mathematics archive, University of St Andrews

13. Charles Dupin – He was born in Varzy in France, the son of Charles Andre Dupin, a lawyer, and Catherine Agnes Dupin. He studied geometry with Monge at the École Polytechnique and then became a naval engineer, from 1807 he was responsible for the restoration of the damaged port and arsenal at Corfu. In 1813 he founded the Toulon Maritime Museum, in 1819 he was appointed professor at the Conservatoire des Arts et Métiers, he kept this post until 1854. In 1822, he was elected a member of the Royal Swedish Academy of Sciences. In 1808, he participated in the Greek science revival by teaching mathematics and mechanics lessons in Corfu, one of his students was Giovanni Carandino, who would go on to be the founder of the Greek Mathematics School in the 1820s. In 1826 he published a map showing the distribution of illiteracy in France, using shadings. Duplin had been inspired by the work of the German statisticians Georg Hassel, in addition, he had a political career and was appointed to the Senate in 1852. His mathematical work was in descriptive and differential geometry and he was the discoverer of conjugate tangents to a point on a surface and of the Dupin indicatrix. Discours et leçons sur lindustrie, le commerce, la marine, media related to Charles Dupin at Wikimedia Commons Quotations related to Charles Dupin at Wikiquote Entry in MacTutor History of Mathematics

14. Joseph Fourier – The Fourier transform and Fouriers law are also named in his honour. Fourier is also credited with the discovery of the greenhouse effect. Fourier was born at Auxerre, the son of a tailor and he was orphaned at age nine. Fourier was recommended to the Bishop of Auxerre, and through this introduction, the commissions in the scientific corps of the army were reserved for those of good birth, and being thus ineligible, he accepted a military lectureship on mathematics. He took a prominent part in his own district in promoting the French Revolution and he was imprisoned briefly during the Terror but in 1795 was appointed to the École Normale, and subsequently succeeded Joseph-Louis Lagrange at the École Polytechnique. Fourier accompanied Napoleon Bonaparte on his Egyptian expedition in 1798, as scientific adviser, cut off from France by the English fleet, he organized the workshops on which the French army had to rely for their munitions of war. He also contributed several papers to the Egyptian Institute which Napoleon founded at Cairo. After the British victories and the capitulation of the French under General Menou in 1801, in 1801, Napoleon appointed Fourier Prefect of the Department of Isère in Grenoble, where he oversaw road construction and other projects. However, Fourier had previously returned home from the Napoleon expedition to Egypt to resume his academic post as professor at École Polytechnique when Napoleon decided otherwise in his remark. The Prefect of the Department of Isère having recently died, I would like to express my confidence in citizen Fourier by appointing him to this place, hence being faithful to Napoleon, he took the office of Prefect. It was while at Grenoble that he began to experiment on the propagation of heat and he presented his paper On the Propagation of Heat in Solid Bodies to the Paris Institute on December 21,1807. He also contributed to the monumental Description de lÉgypte, Fourier moved to England in 1816. Later, he returned to France, and in 1822 succeeded Jean Baptiste Joseph Delambre as Permanent Secretary of the French Academy of Sciences, in 1830, he was elected a foreign member of the Royal Swedish Academy of Sciences. In 1830, his health began to take its toll, Fourier had already experienced, in Egypt and Grenoble. At Paris, it was impossible to be mistaken with respect to the cause of the frequent suffocations which he experienced. A fall, however, which he sustained on the 4th of May 1830, while descending a flight of stairs, shortly after this event, he died in his bed on 16 May 1830. His name is one of the 72 names inscribed on the Eiffel Tower, a bronze statue was erected in Auxerre in 1849, but it was melted down for armaments during World War II. Joseph Fourier University in Grenoble is named after him and this book was translated, with editorial corrections, into English 56 years later by Freeman

15. Pierre-Simon Girard – Pierre-Simon Girard was a French mathematician and engineer, who worked on fluid mechanics. A prodigy who invented a water turbine at the age of ten and he was in charge of planning and construction of the Amiens canal and the Ourcq canal. He collaborated with Gaspard de Prony on the Dictionnaire des Ponts et Chaussées and he wrote works on fluids and on the strength of materials. In 1799 he led a cultural and scientific expedition to Upper Egypt and he died in Paris, aged 71. Antoine Picon, Linvention de lingenieur moderne, ISBN 2-85978-178-1 André Guillerme, Bâtir la ville – révolutions industrielles dans les matériaux de construction. ISBN 2-87673-203-3 Stephen Timoshenko, History of strength of materials

16. Jean Nicolas Pierre Hachette – Jean Nicolas Pierre Hachette, French mathematician, was born at Mézières, where his father was a bookseller. For his early education he proceeded first to the college of Charleville, in 1788 he returned to Mézières, where he was attached to the school of engineering as draughtsman to the professors of physics and chemistry. In 1793 he became professor of hydrography at Collioure and Port-Vendre, towards the close of 1794, when the Ecole Polytechnique was established, he was appointed along with Monge over the department of descriptive geometry. There he instructed some of the ablest Frenchmen of the day, among them SD Poisson, François Arago, accompanying Guyton de Morveau in his expedition, earlier in the year, he was present at the battle of Fleurus, and entered Brussels with the French army. In 1816, on the accession of Louis XVIII, he was expelled from his chair by government and he retained, however, till his death the office of professor in the faculty of sciences in the Ecole Normale, to which he had been appointed in 1810. The necessary royal assent was in 1823 refused to the election of Hachette to the Académie des Sciences, and it was not till 1831, after the Revolution and he died at Paris on 16 January 1834. Hachette was held in esteem for his private worth, as well as for his scientific attainments. His labours were chiefly in the field of geometry, with its application to the arts. Hachettes principal works are, Deux Suppléments à la Géométrie descriptive de Monge Éléments de géométrie à trois dimensions Collection des épures de géométrie, applications de géométrie descriptive Traité de géométrie descriptive, etc. Traité élémentaire des machines Correspondance sur lÉcole Polytechnique He also contributed many papers to the leading scientific journals of his time. For a list of Hachettes writings see the Catalogue of Scientific Papers of the Royal Society of London, also F Arago, Œuvres, oConnor, John J. Robertson, Edmund F. Jean Nicolas Pierre Hachette, MacTutor History of Mathematics archive, University of St Andrews and this article incorporates text from a publication now in the public domain, Chisholm, Hugh, ed. Hachette, Jean Nicolas Pierre

17. Charles Marie de La Condamine – Charles Marie de La Condamine was a French explorer, geographer, and mathematician. He spent ten years in present-day Ecuador measuring the length of a degree latitude at the equator, furthermore he was a contributor to the Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers. Charles Marie de La Condamine was born in Paris as a son of parents, Charles de La Condamine. He studied at the Collège Louis-le-Grand where he was trained in humanities as well as in mathematics, after finishing his studies, he enlisted in the army and fought in the war against Spain. After returning from the war, he acquainted with scientific circles in Paris. On 12 December 1730 he became a member of the Académie des Sciences and was appointed Assistant Chemist at the Academy, the next year he sailed with the Levant Company to Constantinople, where he stayed five months. After returning to Paris, La Condamine submitted in November 1732 a paper to the Academy entitled Mathematical and Physical Observations made during a Visit of the Levant in 1731 and 1732. Three years later he joined an expedition to present-day Ecuador which had the aim of testing a hypothesis of Isaac Newton, Newton had posited that the Earth is not a perfect sphere, but bulges around the equator and is flattened at the poles. Newtons opinion had raised a controversy among French scientists. On 16 May 1735, La Condamine sailed from La Rochelle accompanied by Godin, Bouguer, after stopovers in Martinique, Saint-Domingue, and Cartagena, they came to Panama where they crossed the continent. Finally the expedition arrived at the Pacific port of Manta, La Condamines associations with his colleagues were unhappy. He joined the group again on 4 June 1736 in the city of Quito, La Condamine is credited with introducing samples of rubber to the Académie Royale des Sciences of France in 1736. In 1751, he presented a paper by François Fresneau to the Académie which described many of the properties of rubber and this has been referred to as the first scientific paper on rubber. The scientists spent a month performing triangulation measurements in the Yaruqui plains — from 3 October to 3 November 1736 —, after they had come back to Quito, they found that subsidies expected from Paris had not arrived. La Condamine, who had taken precautions and had made a deposit on a bank in Lima and he prolonged this journey somewhat to study the cinchona tree with its medicinally active bark, the tree being hardly known in Europe. After returning to Quito on 20 June 1737, he found that Godin refused to disclose his results, the two men continued with their length measurements in the mountainous and inaccessible region close to Quito. When in December 1741 Bouguer detected an error in a calculation of La Condamines, however, working separately, the two completed their project in May 1743. Insufficient funds prevented La Condamine from returning to France directly, thus La Condamine chose to return by way of the Amazon River, a route which is longer and more dangerous

18. Philippe de La Hire – Philippe de La Hire was a French painter, mathematician, astronomer, and architect. According to Bernard le Bovier de Fontenelle he was an academy unto himself and he was born in Paris, the son of Laurent de La Hire, a distinguished artist and Marguerite Coquin. In 1660, he moved to Venice for four years to study painting, upon his return to Paris, he became a disciple of Girard Desargues from whom he learned geometrical perspective and was received as a master painter on August 4,1670. His paintings have sometimes confused with those of his son, Jean Nicolas de La Hire. He also began to study science and showed an aptitude for mathematics, from 1679–1682 he made several observations and measurements of the French coastline, and in 1683 aided in mapping France by extending the Paris meridian to the north. In 1683 La Hire assumed the chair of mathematics at the Collège Royal, from 1687 onwards he taught at the Académie d’architecture. La Hire wrote on methods,1673, on conic sections,1685, a treatise on epicycloids,1694, one on roulettes,1702. His works on conic sections and epicycloids were based on the teaching of Desargues and he also translated the essay of Manuel Moschopulus on magic squares, and collected many of the theorems on them which were previously known, this was published in 1705. He also published a set of tables in 1702. La Hires work also extended to descriptive zoology, the study of respiration, two of his sons were also notable for their scientific achievements, Gabriel-Philippe de La Hire, mathematician, and Jean-Nicolas de La Hire, botanist. Mons La Hire, a mountain on the Moon, is named for him, unless otherwise stated La Hires works are in French. In, Histoire de lAcadémie royale des sciences, p, La Hire, Philippe de la, vol. 2, pp. 662–664, in The Dictionary of Seventeenth-Century French Philosophers, oConnor, John J. Robertson, Edmund F. Philippe de La Hire, MacTutor History of Mathematics archive, University of St Andrews. Philippe de La Hire at the Catholic Encyclopedia This text incorporates public domain material from the Rouse History of Mathematics

19. Joseph-Louis Lagrange – Joseph-Louis Lagrange, born Giuseppe Lodovico Lagrangia or Giuseppe Ludovico De la Grange Tournier, was an Italian and French Enlightenment Era mathematician and astronomer. He made significant contributions to the fields of analysis, number theory, in 1787, at age 51, he moved from Berlin to Paris and became a member of the French Academy of Sciences. He remained in France until the end of his life, Lagrange was one of the creators of the calculus of variations, deriving the Euler–Lagrange equations for extrema of functionals. He also extended the method to take into account possible constraints and he proved that every natural number is a sum of four squares. His treatise Theorie des fonctions analytiques laid some of the foundations of group theory, in calculus, Lagrange developed a novel approach to interpolation and Taylor series. Born as Giuseppe Lodovico Lagrangia, Lagrange was of Italian and French descent and his mother was from the countryside of Turin. He was raised as a Roman Catholic, a career as a lawyer was planned out for Lagrange by his father, and certainly Lagrange seems to have accepted this willingly. He studied at the University of Turin and his subject was classical Latin. At first he had no enthusiasm for mathematics, finding Greek geometry rather dull. It was not until he was seventeen that he showed any taste for mathematics – his interest in the subject being first excited by a paper by Edmond Halley which he came across by accident. Alone and unaided he threw himself into mathematical studies, at the end of a years incessant toil he was already an accomplished mathematician, in that capacity, Lagrange was the first to teach calculus in an engineering school. In this Academy one of his students was François Daviet de Foncenex, Lagrange is one of the founders of the calculus of variations. Starting in 1754, he worked on the problem of tautochrone, Lagrange wrote several letters to Leonhard Euler between 1754 and 1756 describing his results. He outlined his δ-algorithm, leading to the Euler–Lagrange equations of variational calculus, Lagrange also applied his ideas to problems of classical mechanics, generalizing the results of Euler and Maupertuis. Euler was very impressed with Lagranges results, Lagrange published his method in two memoirs of the Turin Society in 1762 and 1773. Many of these are elaborate papers, the article concludes with a masterly discussion of echoes, beats, and compound sounds. Other articles in volume are on recurring series, probabilities. The next work he produced was in 1764 on the libration of the Moon, and an explanation as to why the face was always turned to the earth

20. Bernard Lamy – Bernard Lamy was a French Oratorian, mathematician and theologian. After studying in Le Mans, he went to join the Maison dInstitution in Paris, in 1658 he entered the congregation of the Oratory. Lamy became professor of classics at Vendôme in 1661, and at Juilly in 1663, after teaching a few years at Le Mans he was appointed to a chair of philosophy in the University of Angers. Here his teaching was attacked on the ground that it was too exclusively Cartesian and he was then sent by his superiors to Grenoble, where, thanks to the protection of Cardinal Le Camus, he again took up his courses of philosophy. In 1686 he returned to Paris, stopping at the seminary of Saint Magloire, and in 1689 he was sent to Rouen and his best known work is the Traité de Mécanique, showing the parallelogram of force. He also wrote Traité de la grandeur en general and Les éléments de géometrie and his writings are numerous and varied. Among them may be mentioned, La Rhétorique ou lart de parler, apparatus ad Biblia Sacra, etc. translated into French by order of the Bishop of Châlons under the title Introduction a la lecture de lEcriture Sainte. Harmonia, sive Concordia quatuor Evangelistarum, a harmony or concordance of the Four Gospels, in this work he contends that John the Baptist was twice cast into prison, first in Jerusalem by order of the Sanhedrin, and later by Herod in Galilee. He maintains also that the Saviour and His Apostles did not eat the paschal lamb at the Last Supper, and he considers Mary Magdalen, Mary the sister of Lazarus, and the sinner mentioned in Luke, vii,37 sqq. to be one and the same person. These and other opinions involved him in controversy with Bulteau, pastor of Rouen, Jean Piénud, Le Nain de Tillemont, apparatus Biblicus, which is a development of his introduction. It was translated into French by Abbé de Bellegarde and by Abbé Boyer, défense de lancien sentiment de lEglise latine touchant loffice de sainte Madeleine. A volume of commentaries on his previous harmony of the Four Gospels, a Latin treatise on the Ark of the Covenant, a posthumous work published by Père Desmollets, who prefixed to the volume a biography of the author. College of Juilly Lamis theorem List of Roman Catholic scientist-clerics François Girbal, Bernard Lamy, étude biographique et bibliographique, París, regnier in Fulcran Vigouroux, Dictionnaire de la Bible, s. v. OConnor, John J. Robertson, Edmund F, Bernard Lamy, MacTutor History of Mathematics archive, University of St Andrews. This article incorporates text from a now in the public domain, Herbermann, Charles

21. Pierre-Simon Laplace – Pierre-Simon, marquis de Laplace was an influential French scholar whose work was important to the development of mathematics, statistics, physics and astronomy. He summarized and extended the work of his predecessors in his five-volume Mécanique Céleste and this work translated the geometric study of classical mechanics to one based on calculus, opening up a broader range of problems. In statistics, the Bayesian interpretation of probability was developed mainly by Laplace, Laplace formulated Laplaces equation, and pioneered the Laplace transform which appears in many branches of mathematical physics, a field that he took a leading role in forming. The Laplacian differential operator, widely used in mathematics, is named after him. Laplace is remembered as one of the greatest scientists of all time, sometimes referred to as the French Newton or Newton of France, he has been described as possessing a phenomenal natural mathematical faculty superior to that of any of his contemporaries. Laplace became a count of the Empire in 1806 and was named a marquis in 1817, Laplace was born in Beaumont-en-Auge, Normandy on 23 March 1749, a village four miles west of Pont lEveque in Normandy. According to W. W. Rouse Ball, His father, Pierre de Laplace and his great-uncle, Maitre Oliver de Laplace, had held the title of Chirurgien Royal. It would seem that from a pupil he became an usher in the school at Beaumont, however, Karl Pearson is scathing about the inaccuracies in Rouse Balls account and states, Indeed Caen was probably in Laplaces day the most intellectually active of all the towns of Normandy. It was here that Laplace was educated and was provisionally a professor and it was here he wrote his first paper published in the Mélanges of the Royal Society of Turin, Tome iv. 1766–1769, at least two years before he went at 22 or 23 to Paris in 1771, thus before he was 20 he was in touch with Lagrange in Turin. He did not go to Paris a raw self-taught country lad with only a peasant background, the École Militaire of Beaumont did not replace the old school until 1776. His parents were from comfortable families and his father was Pierre Laplace, and his mother was Marie-Anne Sochon. The Laplace family was involved in agriculture until at least 1750, Pierre Simon Laplace attended a school in the village run at a Benedictine priory, his father intending that he be ordained in the Roman Catholic Church. At sixteen, to further his fathers intention, he was sent to the University of Caen to read theology, at the university, he was mentored by two enthusiastic teachers of mathematics, Christophe Gadbled and Pierre Le Canu, who awoke his zeal for the subject. Here Laplaces brilliance as a mathematician was recognised and while still at Caen he wrote a memoir Sur le Calcul integral aux differences infiniment petites et aux differences finies. About this time, recognizing that he had no vocation for the priesthood, in this connection reference may perhaps be made to the statement, which has appeared in some notices of him, that he broke altogether with the church and became an atheist. Laplace did not graduate in theology but left for Paris with a letter of introduction from Le Canu to Jean le Rond dAlembert who at time was supreme in scientific circles. According to his great-great-grandson, dAlembert received him rather poorly, and to get rid of him gave him a mathematics book

22. Adrien-Marie Legendre – Adrien-Marie Legendre was a French mathematician. Legendre made numerous contributions to mathematics, well-known and important concepts such as the Legendre polynomials and Legendre transformation are named after him. Adrien-Marie Legendre was born in Paris on 18 September 1752 to a wealthy family and he received his education at the Collège Mazarin in Paris, and defended his thesis in physics and mathematics in 1770. He taught at the École Militaire in Paris from 1775 to 1780, at the same time, he was associated with the Bureau des Longitudes. In 1782, the Berlin Academy awarded Legendre a prize for his treatise on projectiles in resistant media and this treatise also brought him to the attention of Lagrange. The Académie des Sciences made Legendre an adjoint member in 1783, in 1789 he was elected a Fellow of the Royal Society. He assisted with the Anglo-French Survey to calculate the distance between the Paris Observatory and the Royal Greenwich Observatory by means of trigonometry. To this end in 1787 he visited Dover and London together with Dominique, comte de Cassini, the three also visited William Herschel, the discoverer of the planet Uranus. Legendre lost his fortune in 1793 during the French Revolution. That year, he also married Marguerite-Claudine Couhin, who helped him put his affairs in order, in 1795 Legendre became one of six members of the mathematics section of the reconstituted Académie des Sciences, renamed the Institut National des Sciences et des Arts. Later, in 1803, Napoleon reorganized the Institut National, and his pension was partially reinstated with the change in government in 1828. In 1831 he was made an officer of the Légion dHonneur, Legendre died in Paris on 10 January 1833, after a long and painful illness, and Legendres widow carefully preserved his belongings to memorialize him. Upon her death in 1856, she was buried next to her husband in the village of Auteuil, where the couple had lived, Legendres name is one of the 72 names inscribed on the Eiffel Tower. Today, the term least squares method is used as a translation from the French méthode des moindres carrés. Around 1811 he named the gamma function and introduced the symbol Γ normalizing it to Γ = n, in 1830 he gave a proof of Fermats last theorem for exponent n =5, which was also proven by Lejeune Dirichlet in 1828. In number theory, he conjectured the quadratic reciprocity law, subsequently proved by Gauss, in connection to this and he also did pioneering work on the distribution of primes, and on the application of analysis to number theory. His 1798 conjecture of the prime number theorem was proved by Hadamard. He is known for the Legendre transformation, which is used to go from the Lagrangian to the Hamiltonian formulation of classical mechanics, in thermodynamics it is also used to obtain the enthalpy and the Helmholtz and Gibbs energies from the internal energy