William Jones, Welsh-English mathematician and academic (b. 1675)
William Jones, FRS (1675 – 1 July 1749) was a Welsh mathematician, most noted for his use of the symbol π (the Greek letter Pi) to represent the ratio of the circumference of a circle to its diameter. He was a close friend of Sir Isaac Newton and Sir Edmund Halley. In November 1711 he became a Fellow of the Royal Society, and was later its vice-president.