ARCHIME`DES OF SYRACUSE, the greatest mathematician of antiquity, a man of superlative inventive power, well skilled in all the mechanical arts and sciences of the day.  When Syracuse was taken by the Romans, he was unconscious of the fact, and slain, while busy on some problem, by a Roman soldier, notwithstanding the order of the Roman general that his life should be spared.  He is credited with the boast:  “Give me a fulcrum, and I will move the world.”  He discovered how to determine the specific weight of bodies while he was taking a bath, and was so excited over the discovery that, it is said, he darted off stark naked on the instant through the streets, shouting “Eureka!  Eureka! I have found it!  I have found it!” (287-212 B.C.).

ARCHIMED`ES SCREW, in its original form a hollow spiral placed slantingly to raise water by revolving it.

ARCHIPEL`AGO, originally the AEgean Sea, now the name of any similar sea interspersed with islands, or the group of islands included in it.

ARCHITRAVE, the lowest part of an entablature, resting immediately on the capital.

AR`CHON, a chief magistrate of Athens, of which there were nine at a time, each over a separate department; the tenure of office was first for life, then for ten years, and finally for one.

ARCHY`TAS OF TARENTUM, famous as a statesman, a soldier, a geometrician, a philosopher, and a man; a Pythagorean in philosophy, and influential in that capacity over the minds of Plato, his contemporary, and Aristotle; was drowned in the Adriatic Sea, 4th century B.C.; his body lay unburied on the shore till a sailor humanely cast a handful of sand on it, otherwise he would have had to wander on this side the Styx for a hundred years, such the virtue of a little dust, munera pulveris, as Horace calls it.

ARCIS`-SUR-AUBE (3), a town 17 m.  N. of Troyes, in France, birthplace of Danton; scene of a defeat of Napoleon, March 1814.

AR`COT, the name of two districts, N. and S., in the Presidency of Madras; also chief town (11) in the district, 65 m.  SW. of Madras; captured by Clive in 1787; once the capital of the Carnatic.

ARCTIC OCEAN, a circular ocean round the N. Pole, its diameter 40 deg., with low, flat shores, covered with ice-fields, including numerous islands; the Gulf Stream penetrates it, and a current flows out of it into the Atlantic.

ARCTU`RUS, star of the first magnitude and the chief in the N. constellation Booetes.

ARDECHE, an affluent of the Rhone, source in the Cevennes; gives name to a department traversed by the Cevennes Mountains.

ARDEN, a large forest at one time in England, E. of the Severn.

ARDEN, ENOCH, hero of a poem by Tennyson, who finds, on his return from the sea, after long absence, his wife, who believed him dead, married happily to another; does not disclose himself, and dies broken-hearted.

ARDENNES, a forest, a tract of rugged woodland on the confines of France and Belgium; also department of France (325), on the borders of Belgium.