Archimedes, of Syracuse, the father of natural philosophy, and by far the greatest mathematician and engineer of antiquity, was born about 287 B.C. He was, according to Plutarch, a relative of King Hiero, and he certainly received the patronage and support of that sovereign. He is said to have visited Alexandria in order to hear Euclid, and to have begun his practical career by draining Egyptian marshes and embanking the Nile. The fragments of his works yet extant show extraordinary mathematical ability, dealing with such subjects as the relations between the volumes of a sphere and a cylinder; the measurement of the area of a circle; the ratio of the circumference to the diameter; the application of conic sections to solid geometry; the quadrature of the parabola; the centre of gravity of planes; and the equilibrium of floating bodies. The principle of the lever was so thoroughly appreciated by him that he is reported to have exclaimed, "Give me a lever of sufficient length, and a point to rest it on, and I will move the earth." When the Romans under Marcellus besieged Syracuse in 212 B.C., he exerted himself actively to contrive means for its defence, and set fire to the hostile fleet by a combination of mirrors and burning glasses. He was killed during the assault on the town, though Marcellus had given special orders that he was to be spared.