D'Alembert, Jean (1717-1783) - called "Le Rond," from the circumstance of his being abandoned when an infant upon the steps of the church of St.Jean-le-Rond - a French writer and mathematician, born in Paris. His father, who abandoned him, provided for his education, and he was put under the care of a foster-mother, for whom he always maintained a great affection. Feom 12 to 17 he was educated at the "College Mazarin," and, after reading law, he was admitted advocate in 1738. But his bent was to geometry. In 1739-40 he contributed papers to the Academy of Science, of which he became a member in 1741. In 1744 he wrote upon the Equilibrium and Movement of Fluids, in 1746 upon the General Cause of Winds, thereby gaining a medal from the Academy of Berlin, in 1749 upon the Precession of the Equinoxes, and in 1752 upon the Resistances of Fluid's. From 1751 to 1772 he was associated with Diderot in producing the Encyclopaedia, for which he wrote a memorable preface (a table of human knowledge), and conducted generally the mathematical and physical as well as some of the literary and philosophical articles. In 1759 he published Elements of Philosophy. He was a sceptic in philosophy, but his views were marked by much discretion. In 1772 he became perpetual secretary of the Academy. He was a friend of Voltaire, and a voluminous correspondence commemorates this friendship. Both Frederick of Prussia and Catherine of Russia made overtures to him, but he was not ambitions of distinction.