Natural philosopher, born at Freshwater, Isle of Wight; was associated with Boyle in the construction of the air-pump, and in 1665 became professor of Geometry in Gresham College, London; was a man of remarkable inventiveness, and quick to deduce natural laws from meagre premises; thus he in some important points anticipated Newton's theory of gravitation, and foresaw the application of steam to machinery; he discovered amongst other things the balance-spring of watches, the anchor-escapement of clocks, the simplest theory of the arch, and made important improvements on the telescope, microscope, and quadrant (1635-1703).