Air balloon

“ 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 balloon, because of its vast size and from its being lighter than the air, is completely at the mercy of the wind. It forms an integral part, so to speak, of the wind for the time being, and the direction of the wind in every instance determines the horizontal motion of the balloon. The force required to propel a balloon against even a moderate breeze would result in its destruction. The balloon cannot be transferred with any degree of certainty from one point of the earth’s surface to another, and hence the chief danger in its employment. ”

“ The balloon then rises high into the air, where the weight of atmosphere pressing upon it is much diminished. The higher it rises the less the pressure becomes, and the gas it holds soon expands so much that, unless a vent is provided for it, the balloon will burst. At the present day the neck of a balloon is always left wide open when the balloon is in the air, to allow of the escape of the gas during the ascent. ”

“ And I do not believe that without such previous study and experience a man is capable of succeeding with an elongated balloon, whose handling is so much more delicate. Before attempting to direct an air-ship, it is necessary to have learned in an ordinary balloon the conditions of the atmospheric medium; to have become acquainted with the caprices of the wind, now caressing and now brutal, and to have gone thoroughly into the difficulties of the ballast problem, from the triple point of view of starting, of equilibrium in the air, and of landing at the end of the trip. ”

“ Directly the balloon rises expansion takes place, owing to the rarefied state of the atmosphere, and the higher it ascends the more rarefied the air becomes, and consequently the less atmospheric pressure is there upon the balloon, the natural result being that the gas expands, and makes its way by degrees out of the neck. If there were no such escape, the balloon would burst. When the neck is wide open, those in the car can see into the middle of the balloon, which has a very curious appearance. ”

“ The balloon is made of long strips of silk, sewn together, and rendered air-tight by means of a coating of caoutchouc. A valve is fitted to the top, and by means of it the aeronaut can descend to the earth at will, by allowing some quantity of the gas to escape. The car in which he sits is suspended to the balloon by a network, which covers the whole structure. ”

“ Fourthly, by an octahedron of glass, heated by the sun, and of which the lower part should be allowed to penetrate the dense cold air, which, pressing up against the rarefied hot air, would raise the balloon. Fifthly, by a car of iron and a ball of magnetised iron, which the aeronaut would keep throwing up in the air, and which would attract and draw up the balloon. The wiseacre who invented these modes of flying in the air seems, some would say, to have been more in want of very strict confinement on the earth than of the freedom of the skies. ”

“ They placed themselves in the car, and, when thrown off from the fastenings, they rose through the air with the speed of an arrow. The height to which the balloon reached made it suddenly dilate, and the network, which was much too small, was stretched to the utmost. The balloon was forced down upon them by the dilation, and one of them, in the endeavour to work the valve, made a rent in the lower part of the globe, from which the gas escaping almost over the heads of the travellers, nearly choked them. ”

“ The gas was renewed by Roziers, and the balloon again rising, extricated itself from among the branches, and soared majestically into the air, followed by the acclamations of the public. This second ascent was very instructive, for it had been often asserted that if ever a balloon fell upon a forest it would be destroyed, and would place those who travelled in it in the greatest peril. This experiment proved that the balloon does not FALL it DESCENDS; that it does not overturn; that it does not destroy itself on trees; that it neither causes death, nor even damage, to its passengers ”

“ But in spite of the high hopes of early aeronauts, and the extravagant prophecies made when the first balloons ascended into the sky, it has long been evident that the balloon alone has not solved the problem of human flight or accomplished the conquest85 of the air. An ordinary balloon is, in fact, nothing more than a mere lifting machine, no more capable of sailing the sky, in the proper sense of the word, than a cork floating in the water is capable of sailing the sea. ”

“ According to its greater or less immersion, therefore, it ballasts or unballasts the airship. The balloon is held by its weight down to almost a fixed level over the waves, yet without danger of its being drawn into contact with them. Every extra foot of guide-rope floating means so much less weight for the balloon to lift and so much automatic remounting into the air. In this way an incessant little tugging toward and away from the waves is produced, an automatic ballasting and unballasting accomplished without loss of ballast. ”

“ The method by which lifting power is obtained in the dirigible is exactly the same as in the case of the balloon.
But once in the air, a balloon is, to all intents and purposes, a part of the atmosphere. There is absolutely no sensation of movement, either vertically or horizontally. The earth appears to drop away from beneath and to sweep by horizontally, and regardless of how violently the wind may be blowing, the balloon is always in a dead calm because it is really part of the wind itself and is traveling with it at exactly the same speed. ”

“ It is all-important that the envelope of a navigable balloon should not lose its shape—that it should be kept distended with sufficient tautness, so that it may be driven through the air with considerable velocity. On this account the non-rigid type depends entirely on the ballonet system, which consists of having one or more small balloons inside the outer envelope, into which air can be pumped by means of a mechanically driven fan or ventilator to compensate for the loss of gas from any cause. ”

“ It is absurd to talk of guiding balloons. How will you set about it? How is it possible that a balloon—say, for instance, like the Flesselles, whose diameter measures 120 feet—can resist and manoeuvre against opposing winds or currents of air? It would require a power equal to 400 horses for the sails of a ship to struggle on equal terms with the wind. ”

“ The chief danger attending a balloon journey in a high wind, supposing no injury has been sustained in filling and launching, results not so much from impact with the ground on alighting as from the subsequent almost inevitable dragging along the ground. The grapnels, spurning the open, will often obtain no grip save in a hedge or tree, and even then large boughs will be broken through or dragged away, releasing the balloon on a fresh career which may, for a while, increase in mad impetuosity as the emptying silk offers a deeper hollow for the wind to catch. ”

“ Before the invention of the balloon men were quite unaware of the nature of the air even a short distance above their heads. In those days high mountain climbing had not come into fashion, and when Pilâtre de Rozier made the first ascent, it was considered very doubtful whether he might be able to exist in the strange atmosphere aloft. Charles and Roberts were the first to make scientific observations from a balloon, for they took up a thermometer and barometer, and made certain rough records, as also did other early aeronauts. ”

“ Striking as the fact is, it would be still more surprising if it were otherwise; for, having once entered a current of air, and surrendered our machine to its guidance, we become, as it were, part of the medium in which we are immersed. The balloon has no longer any will of its own, or of its occupants, except for purposes of ascent or descent. It glides along with the stream, and, coming athwart no obstructions, it knows none of the bumpings to which more grovelling vehicles are exposed. ”

“ Now, when the balloon goes down, it is because it has become heavier than the air around it. It goes down because it tries, as we may say, to get underneath the lighter air. In going up, the air pushed it up; but now the balloon pushes the air up. The balloon presses the air that is below it out of the way so as to get under it. ”

“ Monsieur Nadar, as the reader already knows, scouts the idea of steering balloons.
In reference to this he states with truth that, “a balloon which presents to the action of the atmosphere a volume of from 22,000 to 42,000 (cubic) feet of a gas from ten to fifteen times lighter than air, is, by its very nature, smitten with incapacity to struggle against the slightest current, no matter what may be the resisting motive force which may be imparted to it. Both by its constitution, and by the medium which drives it hither and thither at the pleasure of the winds, it can never become a vessel. ”

“ Something appertaining to it must be victimised, and it is in all ways best that this should be the fabric of the balloon itself. If made of some form, or at least some proportion of linen, this will probably rend ere long, and, allowing the gas to escape, will soon bring itself to rest. On the other hand, if the balloon proper is a silk one, with sound net and in good condition, it is probable that something else will give way first, and that something may prove to be the hapless passenger or passengers. ”

“ Being constructed entirely for the main object in view, the balloon had no true opening in the neck beyond an orifice of about an inch, and by the time a height of 13,000 feet had been reached the gas was streaming violently through this small hole, the entire globe being expanded nearly to bursting point, and the cords designed for rending the balloon very tense. ”

“ More than that, it appears that balloons are unmanageable, and it is to air-vessels, constructed more nearly upon the model of birds, that we must go to find out the secret of aerial navigation. At present, as in former times, we are at the mercy of balloons—globes lighter than the air, and therefore the sport and the prey of tempests and currents. And aeronauts, instead of showing themselves now as the benefactors of mankind, exhibit themselves mainly to gratify a frivolous curiosity, or to crown with eclat a public fete. ”

“ THE Air-Bottle can be attended with no Sort of Danger. For, if it burst; the only Effect is to raise the Balloon: which is made to descend, at Pleasure, by opening either the lower or upper Valve.
Whereas an interior Balloon condensed with common Air, presses against the surrounding exterior Gass: and the Gass, against the inside of the great Balloon, when the latter is in an elevated and rarefied Atmosphere; which Atmosphere, in Proportion to its Height, makes less Resistance to the Outside of the great Balloon: and thereby encreases its Tendency to a Rupture. ”

“ On the 16th of the same month the Count d’Albon threw off from his gardens at Franconville a balloon inflated with gas, and made of silk, rendered air-tight by a solution of gum-arabic. It was oblong, and measured twenty-five feet in height, and seventeen feet in diameter. To this balloon a cage, containing two guinea-pigs and a rabbit, was suspended. The cords were cut, and the inflated globe rose to an enormous height with the greatest rapidity. ”

“ They derive their appellation from the fact that when charged with hydrogen, or some other form of gas, they are lighter than the air which they displace. Of these three types the free balloon is by far the oldest and the simplest, but it is entirely at the mercy of the wind and other elements, and cannot be controlled for direction, but must drift whithersoever the wind or air currents take it. ”

“ The rapid climb of the first balloon could be attributed to a vertical air current, or to an air layer of variable density, or both. A balloon often develops leaks at high altitudes and then descends to an intermediate altitude where the loss of gas and the denser atmosphere cause it to hover. ”

“ Balloons that really go up are always attractive but by thoughtful planning they can be made much more beautiful. A nice white balloon against a blue sky is very pleasing, but most boys like more color. The hot air balloons are made of tissue paper, and consist of an inverted bag with a light piece of reed at the bottom to keep the mouth open. The most successful shape is shown by Fig. ”

“ The balloon naturally works under the same difficulties as all lighter-than-air craft, that is, there is a constant leakage of the hydrogen through the fabric in addition to that lost by the expansion of the gas on warm days when the summer sun beats down directly on the gas bag. ”

“ The trouble arising from the coasting across country of a fallen and still half-inflated balloon has already been sufficiently illustrated, and needs little further discussion. It is common enough to see a balloon, when full and round, struggling restively under a moderate breeze with a score of men, and dragging them, and near a ton of sand-bags as well, about the starting ground. ”