LEFORT, FRANCOIS. 



LEGRAND, JACQUES-GUILLAUME. 



831 



to fight for the defence of their native country, by none of his 

 lieutf nants was Napoleon more ably seconded than by Lefebvre. At 

 the battles of Champ-Aubert (February 10, 1814), at Arcis-sur-Aube 

 (March 20), and at Mont-Mirail (April 14), he displayed the same 

 gallantry as in the more renowned but not more glorious fields oi 

 Jena, Tudela, and Wagram. It is however stated that Lefebvre 

 greatly influenced the abdication of Napoleon, and at the first resto- 

 ration of Louis XVIII. he was created Chevalier of St. Louis and 

 peer of France. But on the return of his former chief from Elba, we 

 find him again adhering to his fortunes, and accepting a seat in his 

 Chamber of Peers, where however he held himself aloof from all 

 discussions. ('Jdurnal des Debate' of the 10th of April 1814). At 

 the second restoration of the Bourbons, he was excluded from the 

 Chamber of Peers, to which he was recalled in 1819, having been a 

 few years previously reinstated in his rank of marshal. He died at 

 Paris on the 14th of September 1820. 



There was another well-known general of Napoleon, the CODNT 

 CHARLES LEFEBVUE DESXOUETTES, whose name has sometimes been 

 confounded with that of Marshal Lefebvre. He was condemned to 

 death on the second restoration of the Bourbons, but he was enabled 

 to take refuge in the United States. He perished in a shipwreck on 

 the coast of Ireland, as he was returning to Europe, on the 22nd of 

 April 182-2. 



LEFORT, FRANCOIS, was the son of Jacques Lefort, member of 

 the Grand Council of Geneva, in which city he was born in 1656. 

 After having served as a cadet in the Swiss Guards in the service of 

 France, and subsequently in a regiment belonging to the Duke of 

 Courhmd, in the pay of the Dutch, he was induced to try his fortune 

 as a military man in Russia, and obtained a captain's commission from 

 the czar Feodor or Theodore Alexiwich, and greatly distinguished 

 himself in the wars with the Turks and the Tartars. Having in 1678 

 married Mademoiselle Souhai, whose father, a native of Fi-auce, held 

 the rauk of lieutenant-colonel in the Russian service, he revisited his 

 native country in 1682, but, staying only for a few weeks, got back to 

 Russia in time to be in readiness for the crisis which occurred on the 

 death of Theodore. His abilities being well-known, he was appointed 

 by the Prince Galitzin, wlio governed the country under the Princess 

 Sophia, in the name of her two brothers Ivan and Peter, one of the 

 captains of a new body of troops raised to counteract the domination 

 of the Strelitzes, or old national militia. In this capacity he first 

 attracted the attention of the young czar Peter, in the early part of 

 the year 16S3 ; and on the 29th of June in that year he was raised by 

 him to the rank of major. When, in 1689, Peter took refuge in the 

 Troitski convent, Lefort was one of those who joined him there, and 

 on the overthrow of the usurpation of Sophia, which followed, he 

 became the chief minister of the emancipated emperor. Many of 

 Peter's greatest plans are believed to have been suggested by Lefort ; 

 all the czar's measures for civilising and elevating his country found 

 in him, at least, the most able and zealous of seconders and promoters. 

 HoMini; at once the rank of general and of admiral, Lefort was always 

 equally ready for service by land or by sea ; and his active and versa- 

 tile faculties shone as much in civil affairs as in military. At last Peter 

 lost this inestimable servant by his death at Moscow on the 12th of 

 March 1699 : his health bad been for some time declining, and a fever 

 following upon the breaking out of an old wound carried him oil'. 

 Peter lamented him as if he had been a brother. Lefort's moral nature 

 appears to have been as admirable as was his capacity; considerations 

 of self interest were always postponed by him to the public good and 

 the glory of bis sovereign, and a noble contempt of everything mean 

 or mercenary marked the whole of his career. He left a son, but he 

 died at an early age. 



LEGENDKE, ADRIEN-MARIE, an analyst, whose name must 

 follow those of Lagrange and Laplace in the enumeration of the power- 

 ful school which existed in France at the time of the revolution, was 

 bora at Paris in 1761, and died there January 10, 1833. Of his 

 personal life we can only now say that it was passed in strenuous and 

 successful exertions for the advancement of mathematical science and 

 of its applications. He never filled any political post, or took any 

 marked part in public matters : he was, we believe, no favourite of 

 any government, and his scientific fame did not procure him more 

 than a very moderate competency. The writings of M. Legendre 

 consist of various papers in the ' Memoirs ' of the Academy of Sciences, 

 and several separate writings of which we shall give a slight account. 



The first appearance of Legendre as a mathematician was in 1782 as 

 the writer of two papers, one on the motion of resisted projectiles, the 

 other on the attraction of spheroids, which gained prizes from the 

 academies of Berlin and Paris, and a place in the former as the suc- 

 cessor of D'Alembert. In a memoir on double integrals, published in 

 the volume for 1788 (though presented at the end of 1799), be digested 

 a method of transforming an integral with two variables to one depend- 

 ing upon other variables, which he applied to the question of the 

 attraction of spheroids. He was the first who extended the solution 

 of tlii> question by the aid of modern analysis: it being not a little 

 remarkable, that this problem in the year 1773 required the power of 

 Legrange to show that even as much could be done with it by the 

 modern analysis aa had been effected with the ancient methods by 

 Newton and Maclaurin. Various other memoirs by Legendre ref.:r 

 either to points of the integral calculus, or to his geodetical operations. 



BIOO. DIV. VOL. III. 



In 1 787 he was appointed one of the commissioners for connecting the 

 observatories of Greenwich and Paris by a chain of triangles. Cassini 

 de Thury had memorialised the British government on the expediency 

 of this step : the execution of which was committed to General Roy 

 on the English side, and to Legendre, Cassini, and Me"chain on the 

 French. Much of the work was completed in 1787, and a memoir of 

 Legendre, published in the volume for that year, upon some theoret- 

 ical points, contains one of those simple and beautiful theorems which 

 carry the name of their inventors with them for ever. It is the cele- 

 brated proposition relative to the ' spherical excess' of a small spherical 

 triangle. An account of the actual triangles constructed in his survey 

 is contained in the volume for 1788. When the grand French arc of 

 the meridian was completed, Laplace and Legendre were employed to 

 deduce the form of the spheroid which agreed most nearly with all 

 the observations. In the construction of the large trigonometrical 

 tables (which still remain unpublished) he contributed some simpli- 

 fying theorems. In 1806 he published his ' Nouvelles Me'thodes pour 

 la Determination des Orbites des Cometes,' iu which he gives a method 

 the peculiarity of which then was that it allowed of the correction of 

 the original observations at any part of the process. It may be doubtful 

 whether the method itself was an improvement upon those which 

 were then in use ; and if it were, it is still superseded by others 

 posterior to it. But this tract is further remarkable by its containing 

 the first proposal to employ the method of least squares. Whether 

 Legendre had seen the hint of Cotes or not, he made a proposal of 

 great ingenuity, and introduced, as a matter of practical convenience, 

 a method which was afterwards shown by Laplace to be entitled to 

 confidence on the strictest grounds of principle. 



Legendre applied himself at au early period of his life to the develop- 

 ment of those integrals on which the determination of the arcs of au 

 ellipse and hyperbola depend. In the ' Memoirs ' of the Academy for 

 1786 are two papers on the subject written by him. His ' Exercices 

 du Calcul Integral,' published iu 1811, contain, among other matters of 

 high curiosity, an extended view of the same subject. He continued 

 to devote himself assiduously to the cultivation of this new branch of 

 science, and in 1825 and 1826 he produced the two volumes of his 

 ' Traite des Fonctions Elliptiques et des Integrales Euleriennes,' con- 

 taining a digested system, with extensive tables for the computation 

 of the integrals. The work was hardly published when the discoveries 

 of Messrs. Abel and Jacobi appeared. These mathematicians, both 

 then very young, had begun by looking at the subject in another point 

 of view, and had produced results which would have materially simpli- 

 fied a large parb of the work of Legendre, if he had had the good 

 fortune to find them. With a spirit which will always be one of the 

 brightest parts of his reputation, Legendre immediately set about to 

 add the new discoveries to his own work ; and in 1828 and subsequent 

 years appeared three supplements, iu which they are presented in a 

 manner symmetrical with the preceding part of the work, and with 

 the fullest acknowledgment of their value and of the merit of their 

 authors. 



To Legendre is also due the collection of the results obtained upon 

 the theory of numbers, a subject to which he made very remarkable 

 additions. The second edition of his 'Thdorie des Nombrea' was 

 published in 1808, and the third in 1830. 



The best known of Legendre's works is, as might be supposed, his 

 ' Elements of Geometry,' of which Sir David Brewster gave an English 

 translation in 1824, from the eleventh edition : Legendre published 

 his twelfth edition in 1823. Of the finished elegance and power of 

 this very remarkable work it is not easy to speak in adequate terms : 

 and next to the Elements of Euclid, it ought to hold the highest place 

 among writings of the kind. But it would not be difficult to show 

 that much of the rigour of Euclid has been sacrificed, and though 

 those who determine to abandon the latter cannot do better than 

 substitute Legendre's work, we hope that in this country the old 

 Greek will maintain his ground at least until a substitute can be 

 Found who shall give equal rigour of demonstration, as well as greater 

 elegance of form. 



LEGRAND, JACQUES-GUILLAUME, a French architect and a 

 writer on subjects of architecture, was born at Paris May 9th, 1753. 

 When studying in the Ecole des Fonts et Chausse'es he attracted the 

 notice of Perronet, and was, while yet very young, entrusted with the 

 execution of the bridge at Tours. His taste however disposed him 

 far more to architecture than to engineering, and he accordingly 

 placed himself under Blondel, and after his death pursued his studies 

 under Clerisseau, who, esteeming his character 110 less thau his talents, 

 bestowed his daughter upon him in marriage. With Molinos, his 

 friend and his professional associate in most of his works, he made a 

 tour through Italy, and was preparing to investigate the remains of 

 art in Magna Grsecia, when he was recalled home by the government. 

 From that period he was employed during nearly twenty years in 

 restoring several public edifices and erecting others. One of his most 

 noted works, which he executed in conjunction with Molinos, was the 

 timber cupola of the Halle aux Blecis. The Theatre Feydean, the 

 restoration of the Fontaine des Innocens, of the Halle aux Draps, 

 and of the interior of the H6tel Marboouf, besides a number of designs 

 for private individuals, were executed by him. He had been appointed 

 to conduct the repairs of the abbey of St. Denis, and had removed to 

 that place for the purpose of giving his undivided attention to tho 



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