Alembert, John Le Rond D'

, an eminent French philosopher, was born at Paris, Nov. 17, 1717. He derived the name of John le Rond from that of the church near which, after his birth, he was exposed as a foundling; being | the illicit son of Destouches-Canon and Madame de Tencin. His father, informed of this circumstance, listened to the voice of nature and duty, took measures for the proper education of his child, and for his future subsistence in a state of ease and independence.

He received his first education in the college of the Four Nations, among the Jansenists, where he gave early marks of capacity and genius. In the first year of his philosophical studies, he composed a commentary on the epistle of St. Paul to the Romans. The Jansenists considered this production as an omen that portended to the society of Port-Royal a restoration to some part of their ancient splendour, and hoped to find one day in M. d’Alembert a second Paschal. To render this resemblance more complete, they engaged their rising pupil in the study of mathematics; but they soon perceived that his growing attachment to this science was likely to disappoint the hopes they had formed with respect to his future destination; they, therefore, endeavoured to divert him from pursuing it, but their endeavours were fruitless.

At his leaving the college, he found himself alone and unconnected in the world; and sought an asylum in the house of his nurse. He comforted himself with the hope, that his fortune, though not ample, would better the condition and subsistence of that family, which was the only one that he could consider as his own: here, therefore, he took up his residence, resolving to apply himself entirely to the study of geometry. And here he lived, during the space of forty years, with the greatest simplicity, discovering the augmentation of his means only by increasing displays of his beneficence, concealing his growing reputation and celebrity from these honest people, and making their plain and uncouth manners the subject of good-natured pleasantry and philosophical observation. His good nurse perceived his ardent activity; heard him mentioned as the writer of many books; but never took it into her head that he was a great man, and rather beheld him with a kind of compassion. “You will never,” said she to him one day, “be any thing but a philosopher—and what is a philosopher?—a fool, who toils and plagues himself during his life, that people may talk of him when he is no more.

As M. d’Alembert’s fortune did not far exceed the demands of necessity, his friends advised him to think of a profession that might enable him to augment it. He | accordingly turned his views to the law, and was admitted an advocate in 1738, but soon abandoned this plan, and applied to the study of medicine, which he continued only for about a year. Geometry was always drawing him back to his former pursuits; and after many ineffectual efforts to resist its attractions, he renounced all views of a lucrative profession, and gave himself over entirely to mathematics.

In the year 1741, he was admitted member of the academy of sciences; for which distinguished literary promotion, at such an early age, he had prepared the way by correcting the errors of a celebrated work on geometry, which was deemed classical in France. He afterwards set himself to examine, with deep attention and assiduity, what must be the motion of a body which passes from one fluid into another more dense, in a direction not perpendicular to the surface separating the two fluids. Every one knows the phenomenon which happens in this case, and which amuses children under the denomination of ducks and drakes; but M. d’Alembert was the first who explained it in a satisfactory and philosophical manner.

Two years after his election to a place in the academy, he published his treatise on Dynamics. The new principle developed in this treatise consisted in establishing equality, at each instant, between the changes that the motion of a body has undergone, and the forces or powers which have been employed to produce them; or to express them otherwise, in separating into two parts the action of the moving powers, and considering the one as producing alone the motion of the body, in the second instant, and the other as employed to destroy that which it had in the first.

So early as the year 1744, M. d’Alembert had applied this principle to the theory of the equilibrium, and the mq tjon of fluids; and all the problems before solved by geometricians became, in some measure, its corollaries. The discovery of this new principle was followed by that of a new calculus, the first trials of which were published in a “Discourse on the general Theory of the Winds;” to which the prize medal was adjudged by the academy of Berlin in the year 1746, and which was a new and brilliant addition to the fame of M. d’Alembert. This new calculus of partial differences he applied, the year following, to the problem of vibrating chords, whose solution, as well as the theory of the escalations of the air and the propagation qf | sound, had been given but incompletely by the geometricians who preceded kirn. In the year 1749, he furnished a method of apply ing his principle to the motion of any body of a given figure; and he solved the problem of the precession of the equinoxes, determined its quantity, and explained the phenomenon of the nutation of the terrestrial axis discovered by Dr. Bradley.

In 1752, M. d’Alembert published a treatise on the Resistance of Fluids, to which he gave the modest title of an Essay; but which contains a multitude of original ideas and new observations. About the same time, he published, in the Memoirs of the academy of Berlin, Researches concerning the Integral Calculus, which is greatly indebted to him for the rapid progress it has made in the present century.

While the studies of M. d‘Alembert were confined to geometry, he was little known or celebrated in his native country. His connections were limited to a small society of select friends: he had never seen any man in high office except Messrs. d’Argenson. Satisfied with an income which furnished him with the necessaries of life, he did not aspire after opulence or honours; but his reputation at length made its way to the throne, and rendered him the object of royal attention and beneficence. He received also a pension from government, which he owed to the friendship of count d’Argenson.

The tranquillity of M. d‘Alembert was abated when his fame grew more extensive, and when it was known beyond the circle of his friends, that a turn for literature and philosophy accompanied his mathematical genius. Our author’s eulogist ascribes to envy, detraction, and to other motives nearly as ungenerous, all the disapprobation, opposition, and censure that M d’Alembert met with on account of the publication of the famous Encyclopedical Dictionary of Arts and Sciences, in conjunction with Diderot. But when the reader is told that this eulogist is Condorcet, and when he recollects the vast extent of mischief, moral and political, spread over France, and indeed the whole continent, by the impious and disorganizing principles of d’Alembert and his associates in this work, ne will learn to moderate his admiration of “that fine and enlightened turn for literature and philosophy” which Condorcet displayed before the academy in his Eulogy, pronounced but a very few years before its destructive effects were to be made | apparent. We shall not, however, refuse the just tribute of applause to the displays of genius, judgment, and literary taste, with which M. d’Alembert has enriched the work now mentioned. Among others, the preliminary discourse he has affixed to it, concerning the rise, progress, connexions, and affinities of all the branches of human knowledge, is certainly a capital production. Yet we are disposed to question whether the master-builders of this new and stupendous temple of science, for the worship of nature, had really in view the advancement of human knowledge, and the improvement of the arts and sciences. la the inner court of this temple there was a confederacy formed against all those who looked higher than nature, for the principal object of their veneration and confidence, a fact too palpable, nay too boldly avowed, to stand in need of any proof. And if it be thus palpable, what shall we say, not to the philosophy, but the common sense, of these great men, who could for a moment conceive that objects so incompatible were to be promoted by the same means, and that national impiety and national improvement in the arts of science and social life, were to be incorporated in the same system But it would be unnecessary to expatiate, in this sketch, on the evils of a publication, the effects of which have been so widely felt and so generally acknowledged.

Some time after this, d‘Alembert published his Philosophical, Historical, and Philological Miscellanies: these were followed by the Memoirs of Christina queen of Sweden; in which M. d’Alembert brought forward those abstract and impracticable notions respecting the natural rights of mankind which desolated his country; and was bold. enough to assert them as unanswerable propositions. His Essay on the Intercourse of Men of Letters with Persons high in rank and office, was intended, and too well calculated, to excite popular contempt for the privileged orders, of, in the language of Condorcet, to “expose to the eyes of the public the ignominy of those servile chains, which they feared to shake off, or were proud to wear.A lady of the court, hearing one day the author accused of having exaggerated the despotism of the great, and the submission they require, answered slyly, “If he had consulted me, I would have told him still more of the matter.

M. d’Alembert gave very elegant specimens of his literary abilities in his translations of some select pieces of | Tacitus. But these occupations did not divert him from his mathematical studies; for about the same time he enriched the Encyclopedic with a multitude of articles in that line, on irreducible case, curve, equation, differential, &c. and composed his Researches on several important points of the system of the world, in which he carried to a higher degree of perfection the solution of the problem of the perturbations of the planets, that had several years before been presented to the academy.

In 1759, he published his Elements of Philosophy; a work extolled as remarkable for its precision and perspicuity; in which, however, are some tenets relative both to metaphysics and moral science, of the most pernicious kind. The resentment that was kindled (and the disputes that followed it) by the article Geneva, inserted in the Encyclopédie, are well known. M. d‘Alembert did not leave this field of controversy with flying colours. Voltaire was an auxiliary in the contest; but as, in point of candour and decency, he had no reputation to lose; and as he weakened the blows of his enemies, by throwing both them and the spectators into fits of laughter, the issue of the war gave him little uneasiness. It fell more heavily on d’Alembert; and exposed him, even at home, to contradiction and opposition, which it required all the wit and talents of his associates to resist with effect. In those days, however, of philosophical infatuation, even kings were blindly led to assist in undermining their thrones. And on this occasion, Frederic, usually stiled the great Frederic, king of Prussia, offered him an honourable asylum at his court, and the place of president of his academy; and was not offended at his refusal of these distinctions, but cultivated an intimate friendship with him during the rest of his life. He had refused, some time before this, a proposal made by the empress of Russia to intrust him with the education of the grand duke; a proposal accompanied with very tiattering offers.

In the year 1765, he published his dissertation on the Destruction of the Jesuits. This is said to be an impartial piece, although it had not the good fortune to please either party, a circumstance which seems to mark an indecision of argument or of system. It was, however, but very feebly answered.

Beside the works already mentioned, he published nine volumes of memoirs and treatises, under the title of | Opuscules; in which he has solved a multitude of problems relative to astronomy, mathematics, and natural philosophy; of which Condorcet gives a particular account, more especially of those which exhibit new subjects, or new methods of investigation.

He published also Elements of Music; and rendered, at length, the system of Rameau intelligible; but he did not think the mathematical theory of the sonorous body sufficient to account for the rules of that art. He was always fond of music; which, on the one hand, is connected with the most subtle and learned researches of rational mechanics; while, on the other, its power over the senses and the soul exhibits to philosophers phenomena no less singular, and still more inexplicable.

In the year 1772, he was chosen secretary to the French academy. He formed, soon after this preferment, the design of writing the lives of all the deceased academicians, from 1700 to 1772; and in the space of three years he executed this design, by composing 70 eulogies.

M. d‘Alembert died on the 29th of October, 1783. Condorcet and other French writers of his own school attribute to him many amiable lines of candour, modesty, disinterestedness, and beneficence, in his moral character; and we are not disposed to question that his personal virtues might have been many; but his character cannot be justly appreciated without recollecting that he was the mostsubtle agent in that hostility against Christianity which was carried on by Voltaire, Diderot, and others who assisted in the Encyclopaedia. Nor is the extent of their aversion to revealed religion to be discovered so clearly in their writings prepared for the press, for there they affected to disguise it under the mask of an argumentative philosophy, as in their secret correspondence, much of which appears in Beaumarchais’s edition of Voltaire’s works. The abbe Barruel, in his Memoirs of Jacobinism, has produced many proofs from these letters and other documents, that the impiety of Voltaire, d’Alembert, Diderot, &c. was not a personal concern, not an error into which they had separately fallen, and which they separately avowed, but a design consulted upon, and carried on in common among them; that they encouraged each other by frequent letters, deliberated about the means, and combined in the execution; and that whatever they had done before, it evidently | appears from their correspondence, they placed all their hopes in the Encyclopaedia.

The following list contains d’Alembert’s principal works, with their respective dates. 1. “Traite” de Dynamique, Paris, 1743, 4to; second edition in 1758. 2. “Traite de l’Equilibre et du Mouvement des Fluides,Paris, 1744; second edition in 1770. 3. “Reflexions sur la Cause generate des Vents;” which gained the prize at Berlin, 1746; and was printed at Paris in 1747, 4to. 4. “Recherches sur la Precession des Equinoxes, et sur la Nutation de l’Axe de la Terre dans le Systeme Newtonien,Paris, 1749, 4to. 5. “Essais d’une nouvelle theorie du Mouvement des Fluides,Paris, 1752, 4to. 6. “Recherches sur differens Points importans du Systeme du Monde,Paris, 1754 and 1756, 3 vols. 4to. 7. “Elemens de Philosophic,1759. 8. “Opuscules Mathematiques, ou Memoires sur difterens Sujets de Geometric, de Jtfechaniques, d‘Optiques, d’ Astronomic,Paris, 9 vols. 4to, 1761 to 1773. 9. “Elemens de Musique, theorique et pratique, suivant les Principes de M. Rameau, eclaires, developpes, et simplifies,” a Lyon, 1 vol. 8vo. 10. “De la Destruction des Jesuites,1765.

In the Memoirs of the Academy of Paris are the following pieces, by d‘Alembert: viz. Precis de Dynamique, 1743, Hist. 164. Precis de l’Equilibre et de Mouvernent des Fluides, 1744, Hist. 55. Methode generate pour determiner les Orbites et les Mouvements de toutes les Planetes, en ayant egard a leur action mutuelle, 1745, p. 365. Precis des Reflexions sur la Cause Generate des Vents, 1750, Hist. 41. Precis des Recherches sur la Precession des Equinoxes, et sur la Nutation de l‘Axe de la Terre dans le Systeme Newtonien, 1750, Hist. 134. Essai d’une Nouvelle Theorie sur la Resistance des Fluides, 1752, Hist. 116. Precis des Essais d‘une Nouvelle Theorie de la Resistance des Fluides, 1753, Hist. 289. Precis des Recherches sur les differens Points importans du Systeme du Monde, 1754, Hist. 125. Recherches sur la Precession des Equinoxes, et sur la Nutation de l’Axe de la Terre, dans l‘Hypothese de la Dissimilitude des Meridiens, 1754, p. 413, Hist. 116. Reponse a un Article du Memoire de M. l’Abbe de la Caille, sur la Theorie du Soleil, 1757, p. 145, Hist. 118. Addition a ce Memoire, 1757, p. 567, Hist. 118. Précis des Opuscules Mathematiques, 1761, Hist. 86. Précis du troisieme volume des Opuscules | Mathématiques, 1764, Hist. 92. Nouvelles Recberches sur les Verres Optiques, pour servir de suite à la théorie qui en à été donnée dans le volume 3e des Opuscules Mathématiques: Premier Mémoire, 1764, p. 75, Hist. 175. Nouvelles Recherches sur les Verres Optiques, pour servir de suite à la théorie qui en à été donnée dans le troisième volume des Opuscules Mathématiques. Second Mémoire, 1765, p. 53. Observations sur les Lunettes Achromatiques, 1765, p. 53, Hist. 119. Suite des Recherches sur les Verres Optiques. Troisième Mémoire, 1767, p. 43, Hist. 153. Recherches sur le Calcul Intégral, 1767, p. 573. Accident arrivé par l‘Explosion d’une Meule d’Emouleur, 1768, Hist. 31. Précis des Opuscules de Mathématiques, 4e et 5e volumes. Leur Analyse, 1768, Hist. 83. Recherches sur les Mouvemens de l‘Axe d’une Planete quelconque dans l’hypothese de la Dissimilitude des Méridienes, 1768, p. 1, Hist. 95. Suite des Recherches sur les Mouvemens, &c. 1768, p. 332, Hist. 95. Recherches sur le Calcul Intégral, 1769, p. 73. Mémoire sur let Principes de la Mech. 1769, p. 278.

And in the Memoirs of the Academy of Berlin, are the following pieces, by our author: viz. Recherches sur le Calcul Intégral, premiere partie, 1746. Solution de quelques problemes d’Astronomic, 1747. Recherches sur la courbe que forme une Corde Tendue mise en Vibration, 1747. Suite des recherc lies sur le Calcul Intégral, 1748. Lettre à M. de Maupertuis, 1749. Addition aux recherches sur la courbe que forme une Corde Tendue mise en Vibration, 1750. Addition aux recherches sur le Calcul Intégral, 1750. Lettre à M. le professeur Formey, -1755. Extr. de differ, lettres à M. de la Grange, 1763. Sur les Tantochrgnes, 1765. Extr. de differ, lettres à M. de la Grange, 1769.

Also in the Memoirs of Turin are, Differentes Lettres à M. de la Grange, en 1764 et 1765, tom. 3, of these Memoirs. Recherches sur differeus sujets de Math, tom. 4.

In 1799, two small volumes of posthumous works were published at Paris, which contain very little that is important, except some letters and memoirs of D’Alembert, written by himself, of which we have availed ourselves in a few particulars. 1

1

Elopes, vol. III. Biog. Universelle. —Hutton’s Mathematical Dictionary. Barruel’s Memoirs of Jacobinism, vol. I.

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