Mythology, the controlling factor in the world's intellectual progress, had given way to philosophy, and now philosophy in its turn was beginning to yield its power into the hands of science.

The first great university of Alexandria, begun under Alexander the Great, flourished under the patronage of the Ptolemies for nearly four centuries. It was the gathering place for philosophers from every part of the world. Its students at one time numbered fourteen thousand souls and its libraries contained seven hundred thousand vol

umes.

Here were made the discoveries of Archimedes in mechanics, of Euclid and Apollonius Pergæus in mathematics, of Hipparchus in astronomy and with the ælopile of Hero, here began the steam engine. All of this great work was done before the year 150 B. C. We need only compare the category of Hero's inventions with the single material notion of Thales, to perceive the radical change in thought which had occurred. It is the contrast of the force-pump and the water-soul. It was not the crude and imperfect classifications of Aristotle which accomplished this. The inductive theory in that stage of the world's history could not have established itself, not merely for want of knowledge of a sufficiency of facts which would demonstrate its truth in any particular instance, but also because there was no group of natural facts which could be clearly seen, unobscured by mists of attending speculation and superstition.

Amid all this activity the progress which was made in knowledge of the amber and of the lodestone was very small. Pliny1 has the dubious assertion that the architect Timochares began to erect a vaulted roof of lodestone in

Singularly enough, as we shall see in dealing with the first-named period, it appears not at all unlikely that the English were then much more familiar with the attraction of jet than they were with that of amber. 1Pliny: lib. xxxiv. 42. Vitruvius: De Archit., lib. iv.; time, circa 31 B. C.

MAGNETIC SUSPENSION.

45

the Temple of Arsinoe (wife and sister of Ptolemy Philadelphus) at Alexandria, in order that the iron statue of the queen might have the appearance of hanging suspended in the air. But this work was never accomplished, says the historian, because both the king and the architect died.

This is the same story which, as we have seen in the preceding chapter, the Jewish writers tell of the suspended golden calves of Jeroboam, and the world has never been able to get rid of it. Again and again has it been pointed out, for a thousand years and more, that no piece of iron can be balanced in the air by magnetic attractions oppositely exerted; but the vitality of the falsehood seems even greater than that of the refutations. At the same time there can be little doubt that in some temple, and probably one in Egypt, and at about the time of the University of Alexandria, there was an object held up apparently by no other support than magnetic attraction; and very probably held down by a wire or cord invisible to the spectators. Ausonius' directly disputes the statement of Pliny that the construction of a magnetic vault was abandoned. St. Augustine, St. Isidore,' and Cedrinus* all affirm the existence of the iron statue suspended between ceiling and pavement. Clement of Alexandria causes the Sibyl to sing of "thou, Serapis lying amid rude stones, thou fallest most miserable in the ruins of Egypt," and his scholiast, Clycas, interprets the "lapides rudos multos" as magnets, of which, he says, "many were used in the temple of Serapis on all sides of an iron sun." So that the statue of Arsinoe, in her own temple never completed, may have become confused with an iron sun which did

2

1 Eidyllum x, Mosella, vers. 314, 320; time, circa 390 A. D.

2 De Civ. Dei, lib., 21, 6; time, circa 415 A. D.

Originum, lib. xvi., cap. 4; time, circa 595 A. D.

'Geo. Cedrinus: Compend. Hist., c. 267; time, circa 1057 A. D. Also Suidas: Lex. cit. sup. Art. Magnet; time, circa 1081 A. D.

3 In Protreptico, 15; time, circa 192 A, D.

exist in the Serapeum; and that there were, in fact, two such different things Ruffinus1 and others assert.

2

But note the expansive character of the tradition, and the variety of its transmutations. The horse of Bellerophon, on the island of Rhodes, says the venerable Bede, ' weighed 5000 pounds, and was suspended by magnets. Martial' says that the effigy of Mausoleus was held over his tomb in like manner. As the story grew older, King Theodoric, in a letter to Boesius, applies it to a statue of Cupid in the temple of Diana of Ephesus. And then last, but not least, it reached its final resting place in the legend of Mahomet's coffin. Since this myth furnishes the substance of one of the most common metaphors in use, the facts on which it rests, or rather does not rest, are worth stating.

After Mahomet's death, the Meccans and Medinans disputed possession of the body. Still another faction wished the sepulchre to be in Jerusalem, as the proper place of burial for all prophets. Finally Abu-Bekr interfered and announced that he had heard Mahomet himself during his life direct the selection of Medina. Thereupon a vault was dug beneath the spot where stood the bed on which the prophet slept, in the house of Ayesha. In order to keep the coffin clear of the floor of the vault, it was supported on nine bricks, the earth being heaped about the sides. That is the entire extent to which the coffin was suspended in the air-namely, by nine bricks put under it."

1Ruffinus: Aquil. lib., vi. Histor., c. 22; time, circa. 390 A. D. S. Prosperus: De Praedicatione, 3, c. 38; time, circa 446 A. D.

2 Beda.: de Sept. Mirac. Mundi; time, circa 703 A. D.

3 Lib. De Spectaculis, time, circa 78 A. D.

4 Cassiodor.: Variat Lib., I, Ep. 45; time, circa 500 A. D.

Gagnier: Histoire de la Vie de Mahomet.

Gibbon's note (the Decline and Fall of the Roman Empire, chap. 50) as to this is as follows: The Greeks and Latins have invented and propagated the vulgar and ridiculous story that Mahomet's iron tomb is suspended in the air at Mecca (oñμa μetewpišóμevov, Laonicus Chalcondyles: De Rebus Turcicis, 1. iii. 66) by the action of equal and potent

LUCRETIUS ON THE MAGNET.

47

The Mahometans have always ridiculed the tradition, and certainly it is exceedingly difficult, short of assuming it to have been made out of whole cloth, to find any basis. for it in the facts above stated. There is, however, another version, credited to one Bremond,' an indefinite "traveler of Marseilles," who asserts that he saw "above Mahomet's tomb a magnet, two feet long and three fingers thick, from which is suspended a golden crescent enriched with jewels, by means of a big nail in the middle;" but this obviously lacks the essential feature of the something being held floating in the air by magnetic attraction.

Meanwhile, the knowledge of the magnet had spread beyond the confines of Greece and Asia Minor, in other directions than to the southward. It had moved to the west and to Rome. The Roman, Lucretius,' in that greatest of all didactic poems, "On the Nature of Things," tells of the Samothracian rings as still existing (95 to 52 B. C.), and as having been seen by himself.

"You may see, sometimes," he says, "five or more suspended in succession and tossing about in the light airs, one always hanging down from one and attached to its lower side, and each in turn, one from the other, experiencing the binding power of the stone: with such a continued current its force flies through all."

Here is the first suggestion of a moving current traversing a conductor, in contra-distinction to a soul or virtue merely pervading the object. The distinction between the

lodestones (Dict. de Bayle. Mahom. Rem. E E. FF.). Without any philosophical inquiries, it may suffice that, 1. The prophet was not buried at Mecca; and 2. That his tomb at Medina, which has been visited by millions, is placed on the ground. (Reland: de Relig. Moham., 1. ii., c. 19, p. 209-211.)

1 Azuni: Dissertation sur la Boussole, Paris, 1810, p. 27.

2 Lucretius: De Natura Rerum, Book 6. Translated by H. A. J. Munro. Cambridge, 1866.

magnetic current flowing through the rings and its effect exerted upon the space around the magnet is also drawn, for in addition to the continuing current, Lucretius says that there streams from the stone "very many seeds, or a current, if you will, which dispels, with blows, all the air which lies between the iron and the stone," thus producing, as he imagines, a vacuum in front of the iron, into which the air pressure "thrusts and pushes it on, as the wind a ship and its sails ;" and on this theory he accounts for attraction. Furthermore, as Lucretius describes his "streams" as continuously circulating around the lodestone, the vortex magnetic theory of Descartes is here curiously foreshadowed, if not actually suggested.

Up to this time, as we have seen, there is nothing in the ancient authors indicating any knowledge by them of the repulsive effect of the magnet. It is always spoken of as drawing the iron. When, however, two magnets are brought together, attraction occurs only when their unlike poles are presented to one another-the north pole attracting the south, and vice versa. But if like poles are approximated, just the opposite result happens, and the magnets mutually repel. It is immaterial whether two lodestones, or one lodestone and a magnetized piece of iron, or two magnetized pieces of iron, such, for instance, as two compass needles, be employed; the result is always the same. Hence, as iron that has been brought into contact with the lodestone (as was the case with the Samothracian rings) very readily becomes magnetized by induction from the stone, it is evident that there was a possibility of two rings having become magnetized in this way, being accidentally approximated with their like poles facing one another, and under conditions when one or the other of them might be free to move under the repulsive force. Whatever may have been observed as to this at an earlier time is not known; but an unmistakable and, probably, the first recorded recognition of the phenomenon appears in the poem of Lucretius.