Page:Encyclopædia Britannica, Ninth Edition, v. 1.djvu/220

Rh 202 AERONAUTICS [FLYING MACHINES. . Dupuy ivis;al)le illoon. tlie resistance offered to tlie air by the envelope of the balloon was sufficient to enable him to reach the ground without injury. And a similar thing took place in one of Mr Glaisher s high scientific ascents (April 18, 1863), when, at a height of about 2 miles, the sea appeared directly underneath; the gas was let out of the balloon as quickly as possible, and the velocity of descent was so great, that the 2 miles of vertical height were passed through in four minutes. Oil the balloon reaching the ground at Newhaven, close to the shore, it was found to be nearly empty. The balloon had, in fact, for the last mile or more, merely acted as a parachute; the shock was a severe one, and all the instruments were broken, but nothing serious resulted to the occupants of the car. Numerous attempts have been made both to direct balloons and contrive independent flying machines. After the invention of the balloon by the brothers Montgolfier, it was at once thought that no very great difficulty would be found in devising a suitable steering apparatus ; in fact, it was supposed that to rise into the air and remain there was the chief difficulty, and that, this being accomplished, the power of directing the aerostat would be a secondary achievement that must follow before long. Accordingly, in most of the early balloons the voyagers took up oars, sails, or paddles, which they diligently worked while in the air; sometimes they thought an effect was produced, and sometimes not. If we consider the number of different currents in the atmosphere, it is no wonder that some should have announced with confidence that their course was changed from that of the wind by means of the sails or oars that they used; in fact, it is not very often that the whole atmosphere up to a considerable height is moving en masse in the same direction, so that generally the course taken by the balloon, as determined merely by joining the places of ascent and descent, is not identical with the direction of the wind, even when it is the same at both places. Although there is no reason w-hy balloons should not be so guided by means of mechanical appliances attached to them as to move in a direction making a small angle with that of the wind, still it must have been evident to any one who has observed a balloon during inflation on a windy day, that any motion in which it would be exposed to the action of a strong current of air must result in its destruction. It has therefore gradually become recognised that the balloon is scarcely a step at all towards a system of aerial navigation ; and many have thought that the principles involved in the construction of a flying machine must be very different from the simple statical equilibrium that subsists when a balloon is floating in the air. &quot; To navigate the air the machine must be heavier than the air,&quot; has fre quently been regarded as an axiom; and there can be no doubt that an apparatus constructed of such light material as is necessary for a balloon must either be destroyed or become ungovernable in a high wind. Recently, however, M. Dupuy de Lome, an eminent French engineer, has con structed and made experiments with a balloon which he considers satisfies some of the conditions. The balloon is spindle-shaped, the longer axis being horizontal, and it contains about 120,000 cubic feet. The car is suspended below the middle of the balloon, and there are provided a rudder and a screw. The rudder consists of a triangular sail placed beneath the balloon and near the rear, and is kept in position by a horizontal yard, about 20 feet long, turning round a pivot in its forward extremity ; the height of the sail is 16 feet, and its surface 160 square feet. Two ropes for working the rudder extend forward to the seat of the steerer, who has before him a compass fixed to the car, the central part of which will contain fourteen men. The screw is carried by the car, and is driven by four or eight men working at a capstan. A trial was made with the machine on February 2, 1872, on a windy day, and M. de Lome considered that he had been enabled by his screw and rudder to alter his course about 12. (See Report of the Aeronautical Society, 1872). Whatever difficulties may present themselves in regu lating the horizontal movement of the balloon, there can be no doubt that the vertical motion could be obtained by means of a screw or other mechanical means ; and the power of being able to ascend or descend without loss of ballast would be a considerable gain. In the opinion of many, however, the balloon is not worth improvement; and as ballooning is now generally practised merely as a spectacle by which the aeronaut or showman gains his living, it is not likely that any advancement will be made. Of flying machines, in which both buoyancy and motion were proposed to be obtained by purely mechanical means, the number has been very great. Most of the projects have been chimerical, and were due to persons possessed of an insufficient knowledge of the principles of natural philosophy, both theoretically and practically. They serve, however, to show how great a number of individuals must have paid attention to the matter, and even at the present time several patents are taken out annually on the subject. We do not propose here to give an account of any of these projects, for but few have ever passed beyond projects, but Avill merely refer to Mr Henson s aerial carriage, which in Hem on 1843 attracted some attention. The apparatus was an nerial elaborate one, and its principal feature was the great 11! expanse of the sustaining planes. The machine was to advance with its front edge a little raised, the effect of which would be to present its under surface to the air over which it was passing; the resistance of this air, acting on it like the strong wind on the sails of a windmill, would, it was thought, prevent the descent of the machine. Mr Henson invented a steam-engine of great lightness, but he proposed that the machine should be started down an inclined plane, so that the steam-engine would only have to make up for the velocity lost by the resistance of the air. The scheme never came to anything. In the still air of a room it is, of course, not difficult to attach an apparatus to a balloon so as to direct its motion, and even models of flying machines have been made which, when tried in a room, seemed moderately successful. Some instruments which would very nearly support themselves in the air were shown -at the Aeronautical Society s exhi bition at the Crystal Palace. A good deal would be accomplished if an accurate knowledge of the exact motion of a bird s wing could be obtained ; in fact, until this is known, or until sufficient experiments on the resistance experienced by different-shaped laminae with different motions are made, there seems little chance of the con struction of a satisfactory flying machine, unless means can be found to make a steam-engine of much less weight than is at present necessary. In 1865 the Aeronautical Society of Great Britain was Aerouai founded, the officers being President, the Duke of Argyle ; cal Sod Treasurer, Mr J. Glaisher; and Secretary, Mr Brearey. It f. Gr p a1 has published an annual report every year since [1873J, con taining selections from the papers read to the society, and abstracts of the discussions that took place thereon at the meetings. The numerous papers submitted to this society bear witness to the great number of minds that are engaged on the solution of the problem of aerial navigation. Of course, not a few of the methods proposed are the fanciful projects of ignorant men, but some show the careful thought and elaborate experiment of trained engineers and other qualified persons. In 1868 the -society held an exhibition of flying machines, c., at the Crystal Palace, which was visited by many persons. A fire-balloon of a M. de la Marne, which should have ascended during this exhibition,
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