# Archimedes (of Syracuse)

### screw fluid equal hydrostatics

[ah®ki **mee** deez] ( *c* .287–212 BC ) Sicilian Greek mathematician and physicist: pioneer of statics and hydrostatics.

A member of a wealthy noble family, Archimedes studied in Alexandria but returned to Syracuse in Sicily, whose king Hieron II was a relative. Archimedes was the finest scientist and mathematician of the ancient world but little is firmly known of his life, although legends exist. He is known to have used experiments to test his theories, which he then expressed mathematically. He devised weapons against the Roman fleet when it attacked Syracuse in 215 BC ; the Romans took the city in 212 BC and Archimedes was killed. Cicero found and restored his tomb in 75 BC .

In mathematics, Archimedes used geometrical methods to measure curves and the areas and volumes of solids (e.g. the volume of a sphere, 4pr 3 /3); he used a close approximation for p (he showed it to be between 223/71 and 220/70) and developed his results without the use of the calculus (which came nearly 2000 years later). He used a new notation to deal with very large numbers, described in his book *Sand-Reckoner* .

In applied mathematics, he created mechanics; his innovations ranged from the directly practical (eg the compound pulley and the Archimedian screw) to derivations of the theory of levers and centres of gravity, forming the basic ideas of statics. He founded hydrostatics, contributing ideas which included specific gravity and the Archimedes principle: this states that when a body is wholly or partly immersed in a fluid, it experiences a buoyant force (upthrust) which shows itself as an apparent loss of weight, equal to the weight of fluid displaced. (The fluid can be liquid or gas.)

Archimedes’ water-screw for moving water up a slope has been claimed to be the helical device from which screws of all kinds developed: screw devices were certainly known to , who was thought by , incorrectly, to have originated the idea of this invaluable mover and fixer. The place of the helix in molecular biology was unknown until over 2000 years later. thought that Archimedes had only as a mathematical equal.

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