D'ALEMBERT, diVliiN'brir' (1717-83). The assumed mune of Jean le Rend, a French mathe matician. philosopher, and encyclopxdist. He was the natural son of Chevalier Dcstouehes and Ma dame de Tencin, and was left as an infant on the steps of the Chapel of Saint .Jean le Bond. from which he received his name. Ile was tenderly reared by a glazier's wife, his father contributing secretly to his support. and was educated by Jansenists at the College Mazarin, where he showed a brilliant promise in mathematics, phy sics, and astronomy, to which he reverted after essaying law and medicine. At twenty-two he published a seholarly Ilemoire cur he (wield in tegral, at twenty-four another, Sur la refraction des corps solides. His 7'raite de dynamiane (1743) marks an epoch in mechanical philosophy. This work is based on the theory known as D'Alembe•t's principle, discovered by him at the age of twenty-six, and expressed in the proposi tion: The impressed forces are equivalent to the effective force. His Reflexions stir la, cause generale des vents (1744) eontains the first conception of the calculus of partial differences. In 1749 he published the first analytical solution of the precession of the equinoxes. Ile was made a member of the Acad emy of Sciences in 1741, and in 1754 of the French Academy, whose perpetual secretary he became in 1772. As such he wrote a series of Eloqes of members deceased between 1770 and 1772. In 1751 he undertook, with Diderot, the editing of the great French Encyclopedie, and, though he withdrew from the editorship in 1758, because of Government interference with the pub lication, he continued to eontribute articles in science and philosophy. Very noteworthy is his preliminary discourse, or general introduction, to the work, in which lie traces in broad outlines the evolution of human society, civilization, sci ence, and art. An article of his on Geneva involved him in a celebrated dispute with Rous seau on the merits of Calvinism and the stage as teachers of morals. Meantime his scientific
work had attracted the attention of Frederick 11., who repeatedly offered him the presidency of the Berlin Academy. Catharine II. of Russia of fered him (1762) 100,000 francs a year as tutor to her son. This he also declined. David Hume left him a legacy of f200, and on the recommen dation of Pope Benediet be was admitted to membership in the Institute of Bologna (1755). But he continued to live simply, being by nature a plain, independent, bluff, benevolent, though sometimes rude man. Ile was a total abstainer from alcohol. His last years are closely associ ated t the name of Mlle. de l'Espinasse ( , whom he learned to admire at the literary salon of Mme. du Deffand (q.v.). She nursed him dur ing a serious illness in 1765, and they were never after separated, though not a breath of scandal attached to their connection till her death (1776), a shock from which he never recovered. D'Alembert is fully as important for his personal ity as for his works. He gave learning an offi cial status in French society and did a great ser vice to letters, both by his example and by his Essai sur les yens de lettres (1753), in fostering the independence of his class from subserviency to social prominence and political power. This essay exposed thoroughly and finally the evils of patronage. His religious opinions, once the sub ject of eager controversy, are revealed as a toler ant theism in his correspondence with Voltaire, published in Bossange's partial edition of D'Alem bert's Works (1821). Condorcet's Eloge of him before the French Academy (1784) gives a sym pathetic yet judicious account of D'Alembert's life and writings. Consult Bertrand, D'Alembert (Paris, 1889).