Rolle, Michel

, a French mathematician, was born at Ambert, a small town in Auvergne, April 21, 1652. His first studies and employments were under notaries and attorneys occupations but little suited to his genius, and therefore he quitted them and went to Paris in 1675, with no other recommendation than that of writing a fine hand, and subsisted by giving lessons in penmanship. But as it was his inclination for the mathematics which had drawn him to that city, he attended the masters in this science, and soon became one himself. Ozanam proposed a question in arithmetic to him, to which Rolle gave a solution so clear and good, that the minister Colbert made him a handsome gratuity, which at last became a fixed pension. He then abandoned penmanship, and gave himself up entirely to algebra and other branches of the mathematics. His conduct in life gained him many friends; in which his scientific merit, his peaceable and regular behaviour, with an exact and scrupulous probity of manners, were conspicuous. He was chosen a member of the ancient academy of sciences in 1685, and named second geometrical-pensionary on its renewal in 1699; which he enjoyed till his death, which happened July 5, 1719, at the age of 67.

The works published by Rolle were, 1. “A Treatise of Algebra,” 1690, 4to. 2. “A method of resolving Indeterminate Questions in Algebra,” in 1699. Besides a great many curious pieces inserted in the Memoirs of the Academy of Sciences, as follow 1. A rule for the approximation of irrational cubes, an. 1666, vol. X. 2. A method of resolving equations of all degrees which are expressed in general terms, an. 1666, vol. X. 3. Remarks upon geometric lines, 1702 and 1703. 4. On the new system of infinity, 1703, p. 312. 5. On the inverse method of tangents, 1705, p. 25, 171, 222. 6. Method of finding the foci of geometric lines of all kinds, 1706, p. 284. 7. On curves, both geometrical and mechanical, with their radii of curvature, 1707, p. 370. 8. On the construction of equations, 1708, and 1709. 9. On the extermination of the unknown quantities in the geometrical analysis, 1709, p. 419. 10. Rules and remarks for the construction of equations, 1711, p. 86. 11. On the application of diophantine rules to geometry, 1712. 12. On a paradox in geometric effections, 1713, p. 243. 13. On geometric constructions, 1713, p. 26J, and 1714, p. 5. ¹