ARCHIMEDES, irli-me'dez, one of the most celebrated among the ancient physicists and geometricians: b. Syracuse about 287 B.C. Though, according to some accounts, a relation and certainly a friend of King Hiero, he ap pears to have borne no public office, but to have devoted himself entirely to science. We cannot fully estimate his services to mathema tics for want of an acquaintance with the previous state of science; still we know that he enriched it with discoveries of the highest importance, upon which the moderns have founded their admeasurements of curvilinear surfaces and solids. Euclid, in his 'Elements,' considers only the relation of some of these magnitudes to each other, but does not com pare them with surfaces and solids bounded by straight lines. Archimedes has developed the propositions necessary for effecting this com parison in his treatises on the sphere and cylin der, the spheroid and conoid, and in his work on the measure of the circle. He rose to still more abstruse considerations in his treatise on the spiral, which, however, even those ac quainted with the subjects can with difficulty comprehend. Archimedes is the only one among the ancients who has left us anything satisfactory on the theory of mechanics, and on hydrostatics. He first taught the principle that a body immersed in a fluid loses as much in weight as the weight of an equal volume of the fluid," and determined, by means of it, that an artist had fraudulently added too much alloy to a crown which King Hiero had ordered to be made of pure gold. He discovered the solution of this problem while bathing; and it is said to have caused him so much joy, that he hastened home from the bath undressed, and crying out, .Eureka! Eureka! gI have found it ; I have found WI' Practical me chanics, also, received a great deal of attention from Archimedes. He is the inventor of the compound pulley, probably of the endless screw, etc. During the siege of Syracuse he devoted all his talents to the defense of his native coun try. Polybius, Livy and Plutarch speak in de
tail with admiration, and probably with exag geration, of the machines with which he re pelled the attacks of the Romans. They make no mention of his having set on fire the enemy's fleet by burning-glasses,— a thing which is in itself very improbable, and related only in the later writings of Galen and Lucian. At the moment when the Romans, under Marcellus, gained possession of the city by assault, tra dition relates that Archimedes was sitting in the market-place absorbed in thought, and con templating some figures which he had drawn in the sand. To a Roman soldier who addressed him, he is related to have cried out, "Disturb not my circle but the rough warrior little heeded his request, and struck him down. The conquest of Syracuse is placed in the year 212 Lc. On his tombstone was placed a cylinder, with a sphere inscribed in it, thereby to im mortalize his discovery of their mutual relation, on which he set particular value. Cicero, who was appointed qumstor over Sicily, found this monument in a thicket which concealed it. Of the works of Archimedes there are extant a treatise on 'Equiponderants and Centres of Gravity,' in which the theory of the lever and other mechanical problems are treated; on the 'Quadrature of the Parabola' ; on the 'Sphere and Cylinder' ; on the 'Dimensions of the Circle' ; on ; on 'Conoids and Spheroids' ; the 'Arenarius,' a speculative treatise intended to refute the popular notion that the number of grains of sand on the sea shore is infinite by showing that a definite num ber might be assigned to a quantity of grains sufficient to fill the sphere of the fixed stars, re markable as containing an anticipation of the modern discovery of logarithms; on 'Floating Bodies' ; a treatise called 'Lemmata,' of doubt ful authenticity, on plane geometry. A very complete and splendid edition of the works of Archimedes issued from the Clarendon Press, at Oxford, in 1792. Other editions appeared in 1881 and 1897.