anger of the gods. The barbarians laughed at the threat. He then constructed a dragon of the most volatile paper, and in this inclosed a mixture of sulphur, pitch, and wax, and so artistically arranged all his materials that when ignited it would illumine the machine and exhibit this legend—'The wrath of God.' The body being formed and the ingredients prepared, he affixed a long tail, and committed the machine to the heavens. Favored by the wind, it soared aloft toward the clouds. The spectacle was terrific. The barbarians beholding it were smitten with the greatest astonishment and fear. . . . Thereupon without delay," says Kircher, "they threw open the gates and suffered the prisoners to go forth in peace."
In the middle ages, anybody at all distinguished by knowledge of science was credited with the art of flying, and indeed in many cases did not scruple to claim it. Albertus Magnus was one of these, but refused to give particulars to the world at large. He tells us, however, how to make thunder. Says he: "Take one pound of sulphur, two pounds of willow carbon, and six pounds of rock-salt, ground very fine in a marble mortar; place where you please in a covering made of flying-papyrus to produce thunder. The covering, in order to ascend and float away, should be long, graceful, and well filled with this powder; but to produce thunder the covering should be short and thick, and half full."
Roger Bacon, an eminent philosopher of the thirteenth century, also claimed to have knowledge of the art of flying, but believed also in the wisdom of silence concerning the details. But in his writings we find flashes of real light. He speaks of the possibility of constructing engines of great power to traverse land and sea; and seems to have been the first to have tolerably clear ideas of the principles involved in the construction of balloons. He describes a large hollow globe of copper or other suitable metal wrought extremely thin. It must then, he says, "be filled with ethereal air or liquid fire, and then be launched from some elevated point into the atmosphere, where it will float like a vessel on the water."
In his day the air was supposed to have a well-defined upper limit, like the water.
Friar Bacon too has been credited with the invention of gunpowder. He was of course accused of holding communion with the devil. Good Pope Nicholas placed his writings under a ban, and his wings were effectually clipped.
Shortly after his time, the project of training up children from infancy to fly received a good deal of attention, and, if we can trust the accounts, considerable progress was made, for it is said that, by combined running and flying, individuals could skim over the ground with great rapidity.
Regiomontanus, a famous mathematician, is said like Archytas to have formed an artificial dove, which flew out to meet the Emperor
