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Astro*Dictionary by Michael Erlewine





1 article for "Archimedes"

Archimedes [Astro*Index]


(BC287-212) Greek mathematician and engineer. Born and died at Syracuse, Sicily.

He studied at Alexandria under Conon (who had studied under Euclid). The son of an astronomer, and possibly related to Hieron II, king of Syracuse, Archimedes did not require support from the Egyptian royalty, and returned to Syracuse. A great scientist and engineer, his equal is not found until Newton, some 2,000 years later.

When King Hieron asked him to determine whether a new crown was made of pure gold (or contained a mixture of silver) without causing damage to the crown, Archimedes discovered the "principle of buoyancy" while stepping into his bath. Noting that the water overflowed, he realized that an object inserted into the water displaced an amount of water equal to the volume of the object. He realized that by comparing the weight of an equal volume of gold to the weight of the crown, he could determine whether silver had been used (gold is less bulky than silver). He yelled "Eureka!" (I've got it!), running naked through the streets of Syracuse to the palace to announce his discovery. (The goldsmith was executed for his fraud.) The mathematics of the Lever were evolved by Archimedes, showing that the weights and distances from a fulcrum were in inverse proportion. He built a device (called the "screw of Archimedes") consisting of a hollow, helical cylinder which, when rotated, served as a water pump; this device was known to the Egyptians much earlier. He may have built a mechanical planetarium. His determination of the value of pi (between 223/71 and 220/70) was based on the perimeters and diameters of two regular polygons (inscribed within and circumscribed outside a circle). When Hannibal, the great Carthaginian general, invaded Italy in BC218, Archimedes had reached old age.

Hannibal's initial military success unnerved king Hieronymus, the grandson of Hieron II, who switched his alliegance from Rome to Carthage, after the disastrous Roman defeat at Cannae. But, the Romans sent general Marcellus against Syracuse, and a 3-year battle against the devices of Archimedes followed. Using large lenses, Archimedes set the fleet on fire; using mechanical cranes, he uplifted the ships and turned them over. He died while engrossed in a mathematical problem at the hands of an impatient Roman soldier.


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