MICHEL, a French mathematician, was born at Ambert in Auvergne in 1652. Although obliged at an early age to become an attorney's clerk, all the young man's tastes were soon concentrated upon mathematics. His work, in course of time, grew intolerable to him. He gave it up in 1675, and went to Paris to seek for a better opportunity of gratifying his master-passion. Supporting himself by teaching writing, he devoted all his spare moments to algebra. So ardently, in fact, did he labour, that his dexterity soon attracted the notice of the minister Colbert, and gained for him a pension. Rolle now entered upon a career of distinction. The recently-instituted Academy of Sciences elected him into their number in 1686. Fresh reputation was gained by his Treatise on Algebra in 1690, and by his Method of resolving Indeterminate Questions in Algebra in 1699. At length, in 1701, he came very prominently before the learned public as a pertinacious objector to the newly-discovered Differential Calculus. Boldly asserting the fallacy of that process, he attempted to show that it could not be applied to certain cases. In vain did Varignon and others prove to him that the error lay in his misapplication of the principles in question. For several years he persisted in his opposition; and it was only shortly before his death in 1719 that he confessed his mistake.