ALEMBERT, JEAN-LE-ROND D*. 



ALEMBERT, JEAK-LE-ROND D'. 



106 



friend, resolved that the latter should keep them till he was made 

 doctor ; but he soon found that he could not send his mathematical 

 genius with them. One book after another was begged back, to 

 refresh his memory upon something which he found he could not 

 keep out of his bead. At la.it. finding his taste too strong for any 

 prudential consideration, he gave up the contest, and resolved to 

 devote himself entirely to that which he liked best. The happiness 

 of his life, when he had made this resolution, is thus described by 

 himself. He says that he awoke every morning thinking with pleasure 

 on the studies of the preceding evening, and on the prospect of con- 

 tinuing them during the day. When his thoughts were called off for 

 a moment, they turned to the satisfaction he should have at the play 

 in the evening ; and between the acts of the piece he meditated on 

 the pleasures of the next morning's study. 



Some memoirs which he wrote in the years 1739 and 1740, as well 

 as some corrections which he made in the ' Analyse De'montre'e ' of 

 Reynau, a work then much esteemed in France, procured him admis- 

 sion to the Academy of Sciences, in 1741, at the age of twenty-four. 

 From this time may be dated the career of honour which ranks him 

 among the greatest benefactors to science of the last century. We 

 will now interrupt the order of his life to specify his principal works. 

 In 17J3 appeared his 'Treatise of Dynamics,' founded upon a general 

 principle which afterwards received the name c-f ' D'Alembert's 

 Principle.' The deductions from this new and fertile source of 

 analytical discovery appeared in rapid succession. In 1744 he pub- 

 lished his ' Treatise on the Equilibrium and Motion of Fluids.' In 

 1746 hia ' Reflections on the General Causes of Winds' obtained the 

 prize of the Academy of Berlin. This treatise will always be remark- 

 able, as the first which contained the general equations of the motion 

 of fluids, as well as the first announcement and use of the calculus of 

 partial differences. In 1747 he gave the first analytical solution of 

 the problem of vibrating chords, and the motion of a column of air ; 

 in 1749 he did the tame for the precession of the equinoxes and the 

 nutation of the earth's axis, the latter of which had been just dis- 

 covered by Bradley. In 1752 he published bis ' Essay on the Resist- 

 ance of Fluids,' a treatise originally written in competition for a prize 

 proposed by the Academy of Berlin, but the decision of which was 

 postponed, and finally awarded to a production which has not since 

 gained any reputation for its author. A misunderstanding between 

 Euler and D'Alembert is asserted. by some French writers as the 

 ground of this rejection, which, resting on the well-known character 

 of Euler, we must be permitted to doubt. In the same year he also 

 edited Rameau's ' Elements of Music,' though his opinions did not 

 entirely coincide with that celebrated system. In 1747 he presented 

 to the Academy of Sciences his 'Essay on the Problem of Three 

 Bodies," and in 1754 and 1756 he published ' Researches on Various 

 1'ointii connected with the System of the Universe." We must com- 

 plete the list of hia mathematical works by mentioning his ' Opus- 

 cules,' collected and published towards the end of bis life, in eight 

 volumes. Though D'Alembert wrote no large system of pure analysis, 

 the various methods and hints which are so richly scattered in his 

 ]>l>y-iuo-mathematical works have always been considered as rendering 

 them a mine of instruction for mathematicians. 



We now turn to his philosophical productions. The French ' Ency- 

 clopddie,' as is well known, was commenced by Diderot and himself, 

 as editors; and it is needless to speak of his celebrated Introductory 

 Discourse, a work which, as Condorcet expresses it, there are only 

 two or three men in a century capable of writing. D'Alembert con- 

 tributed several literary articles ; but on the stoppage of the work by 

 the government, after the completion of the second volume, he 

 retired from the editorship, nor would he resume his functions when 

 permission to proceed was at length obtained. From that time he 

 confined himself entirely to the mathematical part of the work, and 

 hia expositions of the metaphysical difficulties of abstract science are 

 among the clearest and best on record. While engaged on this under- 

 taking, he wrote bis ' Melanges de Philosophic,' &c., ' Memoirs of 

 Christina of Sweden," ' Essay on the Servility of Men of Letters to 

 the Great,' ' Elements of Philosophy,' and a treatise on ' The De- 

 struction of the Jesuits.' He also published translations of several 

 parts of Tacitus, which are admitted by scholars to possess no small 

 degree of merit In 1772, when elected perpetual secretary of the 

 Academy, he wrote the ' Eloges ' of the members who had died from 

 1700 up to that ditc. His correspondence, and some additional 

 pieces, were published after his death. The whole of his works have 

 been collected in one edition by M. Bastion, in eighteen volumes, 

 octavo, Parin, 1805. 



In 1752 Frederic of Prussia, who had conceived the highest esteem 

 for hia writings, endeavoured to attract him to Berlin. D'Alembert 

 refused the offer, but in 1754 he accepted a pension of 1200 francs, 

 lu 17S6, through the friendship of M. D'Argenson, then minister, he 

 obtained the same from Louis XV. In 1755, by the recommendation 

 of Benedict XIV., he was admitted into the Institute of Bologna. In 

 1762 Catharine of Russia requested him to undertake the education of 

 her son, with an income of 100,000 francs. On hia declining the 

 offer, she wrote again to presa him, and Bays in her letter, " I know 

 that your refusal arises from your desire to cultivate your studies and 

 your friendships in quiet. But this is of no consequence : bring all 

 your fricnda with you, and I promise you that both you and they 



shall have every accommodation in my power." D'Alembert was too 

 much attached to his situation and hia income of 1501. a-year to accept 

 even this princely offer. The letter of Catharine it was unanimously 

 agreed to enter on the records of the Academy of Sciences. In 1759 

 Frederic again pressed his coining to Berlin, in a letter in which he 

 says, " I wait in silence the moment when the ingratitude of your own 

 country will oblige you to fly to a laud where you are already natu- 

 ralised in the minds of all who think." In 1763, when D'Alembert 

 visited Frederic, the latter again repeated his offer, which was again 

 declined ; the king assuring him that it was the only false calculation 

 he had ever made in his life. 



We now come to relate the history of a connection which ended by 

 embittering the last years of the life of D'Alembert, and finally, it is 

 supposed, had no small share in sending him to his grave. At the 

 house of a common friend he was in the habit of meeting Mile, de 

 1'Espinasse, a young lady whose talents caused her society to be sought 

 by the elite of the literary world of Paris. Between her and D'Alem- 

 bert a mutual attachment grew up, which though, as appeared after- 

 wards, not very strong on her part, became the moving passion of his 

 future life. When, in 1765, he was attacked by a violent disorder, 

 she insisted on being his attendant, and after his recovery they lived 

 in the same house. It is said that friendship was their only bond of 

 union ; and this may be believed, since iu the then state of opinion, 

 the assertion, if untrue, wou!4 have been unnecessary. The friend- 

 ship, or love, of the lady however found other objects ; and though 

 D'Alembert still retained all his former affection for her, she treated 

 him with contempt and unkiudness. Her death left him inconsolable; 

 and his reflections upon her tomb, published in his posthumous work, 

 present the singular spectacle of a lover mourning for a mistress 

 whose regard for him, as he was obliged to admit to himself, had 

 entirely ceased before her death. After that event, he fell into a 

 profound melancholy, nor did he ever recover his former vivacity. 

 His death took place October 29, 1783. Not having received extreme 

 unction it was with great difficulty that a priest could be found to inter 

 him, and then only on condition that the funeral should be private. 



The character of D'Alembert was one of great simplicity, carried 

 even to bluntness of speech, and of unusual benevolence, mixed with 

 a keen sense of the ridiculous, which exerted itself openly and without 

 scruple upon those who attempted the common species of flattpry. 

 He was the friend of Frederic of Prussia, because that monarch 

 exacted no servility ; and to him onlj-, and two disgraced ministers, of 

 all the great ones of the earth, did D'Alembert ever dedicate a work. 

 He was totally free from envy. Lagrange and Laplace owed some of 

 their first steps in life to him ; though the former had settled a 

 mathematical controversy in favour of Euler and against him. In his 

 dispute with Clairaut on the method of finding the orbit of a comet, 

 and with Rousseau on the article 'Calvin' in the ' Encyclopedic,' he 

 gave his friends no reason to blush for his want of temper. It was 

 his maxim, that a man should be very careful in his writings, careful 

 enough in his actions, and moderately careful in his words ; his 

 observance of the last part of the maxim sometimes made him enemies. 

 The Due de Choiseul, when minister, refused the united solicitations 

 in his favour of the Academy of Sciences for a pension vacant by the 

 death of Clairaut, for more than six months, because he had said, in 

 a letter to Voltaire which was opened at the post-office, " Your 

 protector, or rather your prote'ge', M. de ChoiseuL" He cared nothing 

 for those iu power, at a time when the latter exacted and obtained 

 deference in very small matters. Madame de Pompadour, who hated 

 all the friends of Frederic, refused the request of Marmontel that she 

 would employ her influence with the king in favour of D'Alembivt 

 on one occasion, alleging that the latter had put himself at the head 

 of the Italian party in music. It was his maxim that no man ought 

 to spend money in superfluities while others were in want ; and a 

 friend, who knew him well, declared to the editor of his works, that 

 when hia income amounted to 8200 francs, he gave away the half. 

 His attentions to his foster-mother, to the end of her life, were those 

 of a son. In his account of his own character, a singular mixture of 

 vanity and candour, written in the third person, he speaks as follows : 

 " Devoted to study and privacy till the age of twenty-five, he entered 

 late into the world, and was never much pleased with it. He could 

 never bend himself to learn its usages and language, and perhaps even 

 indulged a sort of petty vanity in despising them. He is never rude, 

 because he is neither brutal nor severe ; but he is sometimes blunt, 

 through inattention or ignorance. Compliments embarrass him, 

 because he never can find a suitable answer immediately ; when he 

 says flattering things, it is always because he thinks them. The basis 

 of hia character is frankness and truth, often rather blunt, but never 

 disgusting. He is impatient and angry, even to violence, when any- 

 thing goes wrong, but it all evaporates in words. He is soon satisfied 

 and easily governed, provided he does not see what you are at ; for 

 his love of independence amounts to fanaticism, so that he often 

 denies himself things which would bo agreeable to him, because he is 

 afraid they would put him under some restraint; which makes some 

 of his friends call him, justly enough, the slave of his liberty." This 

 account agrees very well with that of his friends. 



D'Alembert has been held up to reprobation in this country on 

 account of his religious opinions. But on this point we must observe, 

 that there is a wide line of distinction between him and some of his 



