perfectly."
But how to get this enormous air-boat up to the region of hail? This is a minor detail, respecting which Galien is not clear.
From the labours of Lana and Galien, with their impossible flying machines, the inventor of the balloon could derive no benefit whatever; nor is his fame to be in the least diminished because many had laboured in the same field before him. Nor can the story of the ovoador, or flying man, a legend very confused, and of which there are many versions, have given to Montgolfier any valuable hints. It appears that a certain Laurent de Guzman, a monk of Rio Janeiro, performed at Lisbon before the king, John V.,
Laurent de Guzman's Balloon.
raising himself in a balloon to a considerable height. Other versions of the story give a different date, and assign the pretended ascent to 1709. The above engraving, extracted from the "Bibliothèque de la Rue de Richelieu," is an exact copy of Guzman's supposed balloon.
In 1678 a mechanician of Salle, in Maine, named Besnier invented a flying-machine. The machine consisted of four great wings, or paddles, mounted at the extremities of levers, which rested on the shoulders of the man who guided it, and who could move them alternately by means of his hands and feet. The following description of the machine is given in the Journal de Paris by an eye-witness:—
"The 'wings' are oblong frames, covered with taffeta, and attached to the ends of two rods, adjusted on the shoulders. The wings work up and down. Those in front are worked by the hands; those behind by the feet, which are connected with the ends of the rods by strings. The movements were such that when the right hand made the right wing descend in front, the left foot made the left wing descend behind; and in like manner the left hand in front and the right foot behind acted together simultaneously. This diagonal action appeared very well contrived; it was the action of most quadrupeds as well as of man when walking; but the contrivance, like others of the same kind, failed in not being fitted with gearing to enable the air traveller to proceed in any other direction than that in which the wind blew him. The inventor first flew down from a stool, then from a table, afterwards from a window, and finally from a garret, from which he passed above the houses in the neighbourhood, and then, moderating the working of his machine, he descended slowly to the earth."
Tradition records that under Louis XIV. a certain rope-dancer, named Alard, announced that on a certain day he would perform the feat of flying in the air. We have no description of his wings. It is recorded, however, that he set out on his adventurous flight; but he had not calculated all the necessities of the case, and, falling to the ground, he was dangerously hurt.
Leonardo da Vinci might have known the art of flying in the air, and might even have practiced it. A statement to this effect, at least, is found in several historians. We have, however, no direct proof of the fact.
The Abbé Deforges, of Etampes, announced in the journals in 1772 that he would perform the great feat. On the appointed day multitudes of the curious flocked to Etampes. The abbé's machine was a sort of gondola, seven feet long and about two feet deep. Gondola, conductor, and baggage weighed in all 213 pounds. The pious man believed that he had provided against everything. Neither tempest nor rain should mar his flight, and there was no chance of his being upset; whilst the machine, he had decided, was to go at the rate of thirty leagues an hour.
The great day came, and the abbé, entering his air-boat amidst the applause of the spectators, began to work the wings with which it was provided with great rapidity. "But," says one who witnessed the feat, "the more he worked, the more his machine cleaved to the earth, as if it were part and parcel of it."
Retif de la Brétonne, in his work upon this subject, gives the accompanying picture of a flying man, furnished with very artistically designed wings, fitting exactly to the shoulders, and carrying a basket of provisions, suspended from his waist; and the frontispiece of the "Philosophie sans Prétention" is a view of a flying-machine. In the midst of a frame of light wood sits the operator, steadying himself with one hand, and with the other turning a cremaillère, which appears to give a very quick rotatory movement to two glass globes revolving upon a vertical axis. The friction of the globes is supposed to develop electricity to which his power of ascending is ascribed.
To wings, however, aerial adventurers mostly adhered. The Marquis de Racqueville flew from a window of his
THE FLYING MAN.
hotel, on the banks of the Seine, and fell into a boat full of washerwomen on the river. All these unfortunate attempts were lampooned, burlesqued on the stage, and pursued with the mockery of the public.
Up to this time, therefore, the efforts of man to conquer the air had miscarried. They were conducted on a wrong principle, the machinery employed being heavier than the air itself. But, even before the time of Montgolfier, the principles of aerostation began to be recognised, though nothing was actually done in the way of acting upon them. Thus, in 1767, Professor Black, of Edinburgh, announced in his class that a vessel, filled with hydrogen, would rise naturally in the air; but he never made the experiment, regarding the fact as capable of being employed only for amusement. Finally, Cavallo, in 1782, communicated to the Royal Society of London the experiments he had made, and which consisted in filling soap-bubbles with hydrogen. The bubbles rose in the atmosphere, the gas which filled them being lighter than air.
The Theory of Balloons
CHAPTER III.
THE THEORY OF BALLOONS.
A certain proposition in physics, known as the "Principle of Archimedes," runs to the following effect:—"Every body plunged into a liquid loses a portion of its weight equal to the weight of the fluid which it displaces." Everybody has verified this principle, and knows that objects are much lighter in water than out of it; a body plunged into water being acted upon by two forces—its own weight, which tends to sink it, and resistance from below, which tends to bear it up. But this principle applies to gas as well as to liquids—to air as well as to water. When we weigh a body in the air, we do not find its absolute weight, but that weight minus the weight of the air which the body displaces. In order to know the exact weight of an object, it would be necessary to weigh it in a vacuum.
If an object thrown into the air is heavier than the air which it displaces, it descends, and falls upon the earth; if it is of equal weight, it floats without rising or falling; if it is lighter, it rises until it comes to a stratum of air of less weight or density than itself. We all know, of course, that the higher you rise from the earth the density of the air diminishes. The stratum of air that lies upon the surface of the earth is the heaviest, because it supports the pressure of all the other strata that lie above. Thus the lightest strata are the highest.
The principle of the construction of balloons is, therefore in perfect harmony with physical laws. Balloons are simply globes, made of a light, air-tight material, filled with hot air or hydrogen gas which rise in the air because they are lighter than the air they displace.
The application of this principle appeared so simple, that at the time when the news of the invention of the balloon was spread abroad the astronomer Lalande wrote—"At this news we all cry, 'This must be! Why did we not think of it before?'" It had been thought of before,