Up in the Clouds: Balloon Voyages. Robert Michael BallantyneЧитать онлайн книгу.
gas, will rise. Big balloons and little ones are equally uppish in their tendencies. It is also known that rotundity of form is not essential to the successful rising of a balloon. “Well, then,” says this philosopher, “what is to prevent a man making two balloons, flattish, and in the form of wings, which, instead of flying away with him, as ordinary balloons would infallibly do, should be so proportioned to his size and weight as that they would not do more than raise him an inch or so off the ground, and so keep him stotting and bobbing lightly about, something like the bright thin india-rubber balls with which children are wont to play now-a-days?
“Having attained this position of, so to speak, readiness to fly, there is nothing to prevent him from propelling himself gently along the surface of the ground by means of fans, or, if you choose, small flexible cloth wings attached to the hands and arms. The legs might also be brought into play a little. It is obvious, however, that such wings would require to be mounted only in calm weather, for a breeze of wind would infallibly sweep the flyer off the face of the earth! We would only observe, in conclusion, that, however ridiculous this method of flying may appear in your eyes, this at least may be said in its favour, that whereas all other plans that have been tried have signally failed, this plan has never failed—never having been tried! We throw the idea before a discriminating public, in the hope that some aspiring enthusiast, with plenty of means and nerve, and no family to mourn his loss, may one day prove, to the confusion of the incredulous, that our plan is not a mere flight of imagination!”
When men began to find that wings refused in any circumstances to waft them to the realms of ether, they set about inventing aerial machines in which to ascend through the clouds and navigate the skies.
In the fourteenth century a glimmering of the true principles on which a balloon could be constructed was entertained by Albert of Saxony, a monk of the order of Saint Augustin, but he never carried his theories into practice. His opinion was that, since fire is more attenuated than air, and floats above the region of our atmosphere, all that was necessary would be to enclose a portion of such ethereal substance in a light hollow globe which would thus be raised to a certain height, and kept suspended in the sky, and that by introducing a portion of air into the globe it would be rendered heavier than before, and might thus be made to descend. This was in fact the statement of the principles on which fire-balloons were afterwards constructed and successfully sent up, excepting that air heated by fire, instead of fire itself, was used.
Others who came after Albert of Saxony held the same theory, but they all failed to reduce it to practice, and most of these men coupled with their correct notions on the subject, the very erroneous idea that by means of masts, sails, and a rudder, a balloon might be made to sail through the air as a ship sails upon the sea. In this they seem to have confounded two things which are dissimilar, namely, a vessel driven through water, and a vessel floating in air.
The fallacy here may be easily pointed out. A ship is driven through water by a body in motion, namely, wind, while its rudder is dragged through a body comparatively at rest, namely, water; hence the rudder slides against or is pushed against the water, and according as it is turned to one side or the other, it is pushed to one side or the other, the stern of the ship going along with it, and the bow, of course, making a corresponding motion in the opposite direction. Thus the ship is turned or “steered,” but it is manifest that if the ship were at rest there would be no pushing of the rudder by the water—no steering. On the other hand, if, though the ship were in motion, the sea was also flowing at the same rate with the wind, there would be no flowing of water past the ship, the rudder would not be acted on, and the vessel could not be steered.
Now a balloon, carried by the wind, cannot be steered by a rudder, because it does not, like the ship, rest half in one medium which is in motion, and half in another medium which is at rest. There is no sliding of any substance past its side, no possibility therefore of pushing a rudder against anything. All floats along with the wind.
If, however, the balloon could be made to go faster than the wind, then steering would at once become possible; but sails cannot accomplish this, because, although wind can drive a ship faster than water flows, wind cannot drive a substance faster than itself flows.
The men of old did not, however, seem to take these points into consideration. It yet remains to be seen whether steam shall ever be successfully applied to aerial machines, but this may certainly be assumed in the meantime, that, until by some means a balloon is propelled faster than the wind through the atmosphere, sails will be useless, and steering, or giving direction, impossible.
It was believed, in those early times, when scientific knowledge was slender, that the dew which falls during the night is of celestial origin, shed by the stars, and drawn by the sun, in the heat of the day, back to its native skies. Many people even went the length of asserting that an egg, filled with the morning dew, would, as the day advanced, rise spontaneously into the air. Indeed one man, named Father Laurus, speaks of this as an observed fact, and gravely gives directions how it is to be accomplished. “Take,” says he, “a goose’s egg, and having filled it with dew gathered fresh in the morning, expose it to the sun during the hottest part of the day, and it will ascend and rest suspended for a few moments.” Father Laurus must surely have omitted to add that a goose’s brains in the head of the operator was an element essential to the success of the experiment!
But this man, although very ignorant in regard to the nature of the substances with which he wrought, had some quaint notions in his head. He thought, for instance, that if he were to cram the cavity of an artificial dove with highly condensed air, the imprisoned fluid would impel the machine in the same manner as wind impels a sail. If this should not be found to act effectively, he proposed to apply fire to it in some way or other, and, to prevent the machine from being spirited away altogether by that volatile element, asbestos, or some incombustible material, was to be used as a lining. To feed and support this fire steadily, he suggested a compound of butter, salts, and orpiment, lodged in metallic tubes, which, he imagined, would at the same time heighten the whole effect by emitting a variety of musical tones like an organ!
Another man, still more sanguine than the lest in his aerial flights of fancy, proposed that an ascent should be attempted by the application of fire as in a rocket to an aerial machine. We are not, however, told that this daring spirit ever ventured to try thus to invade the sky.
There can be no doubt that much ingenuity, as well as absurdity, has been displayed in the various suggestions that have been made from time to time, and occasionally carried into practice. One man went the length of describing a huge apparatus, consisting of very long tin pipes, in which air was to be compressed by the vehement action of fire below. In a boat suspended from the machine a man was to sit and direct the whole by the opening and shutting of valves.
Another scheme, more ingenious but not less fallacious, was propounded in 1670 by Francis Lana, a Jesuit, for navigating the air. This plan was to make four copper balls of very large dimensions, yet so extremely thin that, after the air had been extracted, they should become, in a considerable degree, specifically lighter than the surrounding medium. Each of his copper balls was to be about 25 feet in diameter, with the thickness of only the 225th part of an inch, the metal weighing 365 pounds avoirdupois, while the weight of the air which it should contain would be about 670 pounds, leaving, after a vacuum had been formed, an excess of 305 pounds for the power of ascension. The four balls would therefore, it was thought, rise into the air with a combined force of 1220 pounds, which was deemed by Lana to be sufficient to transport a boat completely furnished with masts, sails, oars, and rudders, and carrying several passengers. The method by which the vacuum was to be obtained was by connecting each globe, fitted with a stop-cock, to a tube of at least thirty-five feet long; the whole being filled with water; when raised to the vertical position the water would run out, the stop-cocks would be closed at the proper time, and the vacuum secured. It does not seem to have entered the head of this philosopher that the weight of the surrounding atmosphere would crush and destroy his thin exhausted receivers, but he seems to have been alarmed at the idea of his supposed discovery being applied to improper uses, such as the passing of desperadoes over fortified cities, on which they might rain down fire and destruction from the clouds!
Perhaps the grandest of all the fanciful ideas that have been promulgated on this subject was that