John Wallis

John Wallis was an English clergyman and mathematician, born in Ashford, Kent, in 1616, who is given partial credit for the development of infinitesimal calculus. Between 1643 and 1689 he served as chief cryptographer for Parliament and, later, the royal court. He extended Cavalieri's method of indivisibles through the use of interpolation and, applying Kepler's principle of continuity, developed techniques for the evaluation of integrals. He is credited with introducing the symbol for infinity, and he similarly used one over infinity for an infinitesimal. He studied at Emmanuel College, Cambridge, taking a B.A. in 1637 and an M.A. in 1640, and received a D.D. at Oxford in 1654. He was a contemporary of Isaac Newton and one of the greatest intellectuals of early modern mathematics. He died in 1703.