Brook Taylor. Engraving of Brook Taylor (1685- 1731), British mathematician. Taylor studied at St John's College, Cambridge and was Secretary to the Royal Society during 1714-18. In 1715 he published Methodus incrementorum directa et inversa (Direct and Indirect Methods of Incrementation). This contained a formula for power series expansions (now called Taylor's Theorem). The Methodus also covered the calculus of finite differences and Taylor applied this to the mathematical theory of vibrating strings. Taylor was also an accomplished artist and wrote a book, Linear Perspective, on the theory of perspective in 1715.