(287-212 B.C.) [Illustration: A boat. [TN]] It is scarcely possible to view the vast steamships of our day without reflecting that to a great master of mechanics, upward of two thousand years since, we in part owe the invention of the machine by which these mighty vessels are propelled upon the wide world of waters. This power is an application of "the Screw of Archimedes," the most celebrated of the Greek geometricians. He was born in Sicily, in the Corinthian colony of Syracuse, in the year 287 B.C., and when a very young man, was fortunate enough to enjoy the patronage of his relative Hiero, the reigning prince of Syracuse. The ancients attribute to Archimedes more than forty mechanical inventions--among which are the endless screw; the combination of pulleys; an hydraulic organ, according to Tertullian; a machine called the HELIX, or screw, for launching ships; and a machine called _loculus_, which appears to have consisted of forty pieces, by the putting together of which various objects could be framed, and which were used by boys as a sort of artificial memory. Archimedes is said to have obtained the friendship and confidence of Hiero by the following incident. The king had delivered a certain weight of gold to a workman, to be made into a crown. When the crown was made and sent to the king, a suspicion arose in the royal mind that the gold had been adulterated by the alloy of a baser metal, and he applied to Archimedes for his assistance in detecting the imposture; the difficulty was to measure the bulk of the crown without melting it into a regular figure; for silver being, weight for weight, of greater bulk than gold, any alloy of the former in place of an equal weight of the latter would necessarily increase the bulk of the crown; and at that time there was no known means of testing the purity of metal. Archimedes, after many unsuccessful attempts, was about to abandon the subject altogether, when the following circumstance suggested to his discerning and prepared mind a train of thought which led to the solution of the difficulty. Stepping into his bath one day, as was his custom, his mind doubtless fixed on the object of his research, he chanced to observe that, the bath being full, a quantity of water of the same bulk as his body must flow over before he could immerse himself. He probably perceived that any other body of the same bulk would have raised the water equally; but that another body of the same weight, but less bulky, would not have produced so great an effect. In the words of Vitruvius, "as soon as he had hit upon this method of detection, he did not wait a moment, but jumped joyfully out of the bath, and running forthwith toward his own house, called out with a loud voice that he had found what he sought. For as he ran he called out, in Greek, 'Eureka! Eureka!--I have found it! I have found it!'" When his emotion had sobered down, he proceeded to investigate the subject calmly.