Beside the works already mentioned, he published nine volumes of memoirs and treatises, under the title of " Opus cules ;" in which he has resolved a mul titude of problems relating to astronomy, mathematics, and natural philosophy ; of which his panegyrist, 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 render ed, at length, the system of Rameau in telligible;4Nt he did not think the mathe matical theory of the sonorous body suffi cient to account for the rules of that art. In the year 1772 he was chosen Secretary to the French Academy of Sciences. lie formed, soon after this preferment, the design of writing the lives of all the de ceased academicians, from 1700 to 1772 ; and in the space of three years he exe cuted this design, by composing seventy eulogies.
The correspondence which D' Alembert held with eminent literary characters, and his constant intercourse with learned men of all nations, together with his great in fluence in the academy, concurred to give him a distinguished importance above most of his countrymen. By some, who were jealous of his reputation, he was denominated the Mazarin of literature; but there seems now no doubt, but that his influence was obtained by his great talents and learning, rather than by art ful management and supple address. He was a decided and open enemy to super stition and priestceaft. Without inquiring into the merits of Christianity, he conclu ded, that the religion taught in France was that which believers in general re garded as the true doctrine, and which he rejected as a fable unworthy the atten tion of the philosopher. There is no rea son to think that he ever studied the foundations on which natural and revealed religion were built ; and it is certain that he adopted a system of deified nature, which bereaves the world of a designing cause and presidingintelfigence. He was
zealous even in propagating the opinions which he adopted, and might be regarded as an apostle of atheism. The eccentri city of his opinions did not destroy the moral virtues of his heart. A love of truth, and a zeal for the progress areal science and liberty, formed the basis of his character : strict probity, a noble dis interestedness, and an habitual desire of being useful, were its distinguishing fea tures. To the young, who possessed ta lents and genius, he was a patron and in structor: to the poor and oppressed he be came a firm and generous friend: to those who had shown him kindness, he never ceased to be grateful ; a sure evidence of a great mind. To two ministers. who had befriended him in their prosperity, he de dicated works when they were in disgrace with the court. An instance of a kind, a grateful disposition, was displayed by D'Alembert in early life. His mother, who had infamously disowned and aban doned him, hearing of the greatness of his talents, and of the promise which he gave of future celebrity, obtained an terview, and laid claim to the character of a parent.—"What do I hear," said the indignant youth, " you are the mother-in law, the glazier's wife is my true mother:" indeed he never ceased to testify the affection and gratitude of a child : and under her roof he resided, as we have seen, many years, till an alarming illness made it necessary for him to remove to a more airy lodging. D' Alembert main tained hi; Idyls rank and reputation among mahematimans and philosophers till his death, in October 1783. His loss was doplored by survivors of every country ; but his particular friends and associates exhibited, o n the occasion, every mark of grief, which real and unaffected sorrow can alone supply for undissembled worth.