Wallis, John (wŏlˈĭs) [key], 1616–1703, English mathematician. He was Savilian professor of geometry at Oxford from 1649. He systematized the use of formulas, introduced the symbol ∞ for infinity, and made a study of the quadrature of curves, which he recorded in Arithmetica infinitorum (1655). His collected mathematical works appeared in three volumes (1693–99). He wrote also on grammar, logic, theology, and cryptography.