510 TRANSACTIONS OF THE 



large wiiigs, from the top of a neighboring tower. His ponderous ma- 

 chinery failed to sustain him ; he fell to the ground, broke both his legs, 

 and died in consequence not long after. 



It was not until 1670 that strong ground was taken by Borelli against this 

 kind of aerial navigation in his treatise, De Moiu Aniinalium, in which, 

 by a comparison between the muscles that act on the wings of a bird with 

 those of the breast and arms of a man, he proved the latter to be insufBcient 

 to strike the air with force enough to raise him from the ground. 



The first idea of constructing a body that should rise in the air by its 

 own power, was suggested in the fourteenth century, by Albert, of Saxony, 

 an Augustinian monk, and a commentator on Aristotle, who, accepting the 

 then popular idea, that fire was floating above the atmosphere of the earth, 

 maintained that if it were possible to bring down a portion of this more 

 etherial substance, and enclose it in a ball or globe, it would float in 

 the atmosphere ; while the admission of the air from without would cause it 

 to descend in like proportion. Here was the base of Montgolfier's dis- 

 covery. 



In the beginning of the seventeenth century, Francis Mendoza, a Portu- 

 guese Jesuit, revived the theory of Albert, of Saxony, maintaining that the 

 combustibility of fire was r.o objection to its use in balloons, since its laxity, 

 and the exclusion of air, would prevent its ignition; in this he was sup- 

 ported, in Germany, by Caspar Schott, who declared that such a vessel, 

 furnished with rudder and sails, could safely navigate the sky. 



Various theories of aerostation continued to be agitated from time to 

 time, the chief of which proceeded from the Jesuit Francis Lana. He 

 proposed to employ hollow balls of copper, which, exhausted of their air, 

 would become specifically lighter than the surrounding medium, and thus 

 ascend ; but this theory, defective in many of its calculations, was entirely 

 annihilated by the fact that these balls, if light, enough to float in the 

 atmosphere, would be entirely too thin to resist its external pressure. 



In 1709, Friar Guzman, of Portugal, projected a flying machine, con- 

 structed somewhat in the form of a bird, with long tubes, through which 

 air was to pass to fill wings that were to elevate it. and obtained the royal 

 patronage to a considerable degree ; but the only fruit that ever resulted 

 from this theory was the ascent of a paper basket 200 feet in the air, which 

 won for the good father the reputation of a conjurer. 



The era of the modern balloon was now approaching. In 1706, Henry 

 Cavendish discovered that inflammable air was specifically lighter than the 

 common atmosphere, and suggested to Dr. Black, of Edinburgh, that a 

 bladder filled with the former would rise and sustain itself in the latter. 

 Experiments based on this theory were made by M. Carvallo — first with 

 bladders, that proved too heavy ; then with Chinese paper, that proved 

 permeable to the vapor ; and lastly, by blowing up soap bubbles, inflated 

 with inflammable air. Just at this period, the announcement was made 

 that the theory had already been realized in France, by the brothers Stephen 

 and Joseph Montgolfier ; the former and younger of whom was the first to 



