The truth of these two extraordinary facts is invalidated by the silence of the most authentic historians; and the use of burning-glasses was never adopted in the attack or defence of places. Yet the admirable experiments of a French philosopher [Buffon] have demonstrated the possibility of such a mirror; and, since it is possible, we are more disposed to attribute the art to the greatest mathematicians of antiquity, than to give the merit of the fiction to the idle fancy of a monk or a sophist. According to another story [told by John Malalas[h]], Proclus applied sulphur to the destruction of the Gothic fleet; in a modern imagination, the name of sulphur is instantly connected with the suspicion of gunpowder, and that suspicion is propagated by the secret arts of his disciple Anthemius. [Illustration: A BYZANTINE NOBLE] The fame of Metrodorus the grammarian, and of Anthemius the mathematician and architect, reached the ears of the emperor Justinian, who invited them to Constantinople; and while the one instructed the rising generation in the schools of eloquence, the other filled the capital and provinces with more lasting monuments of his art. In a trifling dispute, relative to the walls or windows of their contiguous houses, he had been vanquished by the eloquence of his neighbour Zeno; but the orator was defeated in his turn by the master of mechanics, whose malicious, though harmless, stratagems are darkly represented by the ignorance of Agathias. In a lower room, Anthemius arranged several vessels or cauldrons of water, each of them covered by the wide bottom of a leathern tube, which rose to a narrow top, and was artificially conveyed among the joists and rafters of the adjacent building. A fire was kindled beneath the cauldron; the steam of the boiling water ascended through the tubes; the house was shaken by the efforts of imprisoned air, and its trembling inhabitants might wonder that the city was unconscious of the earthquake which they had felt.