Archimedes, the most celebrated mechanician of antiquity, born in Syracuse, Sicily, about 287 B. C, died in 212. He is saidto have visited Egypt in early life, and to have invented there several useful hydraulic machines, including the Archimedean screw, which he applied to drainage and irrigation. Vitruvius says that King Hiero, suspecting that a golden crown had been fraudulently alloyed with silver, asked Archimedes to discover if it were so. Going one day into the hath tub, it chanced to be full of water, and he instantly saw that as much water must run over the edge of the tub as was equal to the bulk of his body. Perceiving that this gave him a mode of determining the bulk and specific gravity of the crown, he leaped out of the bath and ran home, crying Eureka, eureka, "I have found it, I have found it." This was the origin of his discovery of the important principle that a body plunged in a fluid loses as much of its weight as is equal to the weight of an equal volume of the fluid. In his old age he defended his native Syracuse against the Romans under Marcellus with great mechanical skill, and later historians say that he burned the Roman ships by concentrating upon them the sun's rays from numerous mirrors.

His purely mathematical works still extant demonstrate him to have far excelled all those who preceded him. The most celebrated are those on the ratio of the sphere and cylinder, on the ratio of the circumference to a diameter, on spiral lines, and on the parabola. He requested a cylinder and sphere to be placed upon his tombstone, and when Marcellus had stormed Syracuse, and Archimedes had been killed by a Roman soldier, the Roman general conferred upon him an honorable burial, and caused the tombstone to be inscribed as he had desired. Cicero, about 140 years afterward, being appointed quaestor over Sicily, sought and found the tomb of Archimedes, overgrown with weeds and thorns.