Although these aerial voyages, which we have thus briefly narrated, arc the most conspicuous in the histo ry of the science, yet many others have been underta ken, both in Britain and on the con'._Ment, which the ingenuity, and the enterprising spirit of the adventurers, the circumstances of unforeseen intricacy and danger they had to encounter ; and, above ail, the scenes of tem pestuous grandeur through which they passed, must ren der subjects of lively interest to the curious : and we regret that, solicitous as we arc to gratify the taste of such a class of readers, our limits prevent us from de tailing the more unimportant and less remarkable voyages that have taken place.
Use of Balloons.
The advantages hitherto derived from aerial naviga tion have by no means proved adequate to the expecta tions excited by the novelty and promising aspect of the science. This failure in their utility may, in a great degree, be 4scribed to the art of steering balloons being still undiscovered : It must also be remembered, that by far the greatest number of aerial voyages w hieh have been attempted, were undertaken purely for the gratifi cation ol curiosity ; and that comparatively few of them have been conducted with the precaution of philosophi cal inquiry, or for the purpose of scientific discovery. In choosing the figures 01 the balloons, likewise, the admiration of the multitude seems more frequently to have been consulted than the fair and equable movement of the machine, or the safety of the aeronaut. A bal loon, constructed in imitation of the human figure, clothed in a flame-coloured robe ; or ol a Pegasus transporting through the clouds a richly-accoutred war rior, could not fail to fascinate the senses of a crowd. The French, indeed, who arc ever ready to apply the discoveries of science to objects of practical utility, during the first war after the overthrow of the monarchy, instituted an academy for the express purpose of im proving the state of aeronautics. This institution was established at the Royal Lodge of Mendon, near Paris, and was conducted with the utmost secrecy. There was a corps of aeronauts, consisting of fifty youths, trained to the service ; and a spherical balloon, 32 feet in diameter, was kept constantly prepared for exerci sing, and fastened to the great terrace of the lodge, in the open air. In favourable weather it was loosened ; and with the car, which contained the colonel of the corps and a pupil, attached to it, it was allowed to as cend from 160 to 240 yards ; but it was still restrained by a cord fastened from below. A balloon, recently filled, required twenty people to hold it ; and, even after the lapse of two months, notwithstanding the loss of gas that had taken place, it could support two persons and ballast in the air. Balloons were here prepared for the service of the different armies ; the Entrtn••nant for the army of the North, the Celeste for that of the Sam bre and Meuse, and the Hercule and intrepid(• for the army of the Rhine and Moselle. The management of the institution was committed to men of eminent repu tation ; the celebrated chemist, Guyton Morveau, ren dered it essential advantages ; and M. Conti was chief
superintendent. It was reported, some years ago, to have been in a very flourishing condition ; hut it is now said to be entirely abandoned. M. Loniet has been very lately employed, by the French government, in making experiments, to ascertain whether balloons might not be advantageously employed in the survey of countries, for the construction of geographical plans. The irre gular motion or the balloon in ascending presented many obstacles to the success of his experiments ; but, nevertheless, M. Lomet conceives that they might be used with great benefit for that purpose. It has like wise been proposed to make an aeronautic telegraph, by which signals might be communicated through the medium of a machine attached to the balloon. The Abbe Bertholon has used balloons in electrical experi ments. Those which he sent up, had long slender wires proceeding from them, with the end terminating in a glass-rod, or other insulating substance ; and from the wires he procured the electric spark.
The respiration is always affected by ascending high into the atmosphere, probably in consequence of the rarefaction of the air; the pulsation is increased, the bead is sometimes swelled, and the throat parched. The temperature, according to the most authentic observa tions, decreases in proportion to the height : whence, to great altitudes, a numbness'is felt, and the propen shy to sleep so irresistibly strong, as in ::onr• eases to have actually overpowered the aeronauts. The mag netic power was lound, by M. Gay Lussac, to prevail at the height of 12,372 fcct, the same as on the stu•:toe of the earth. At the same time, other aeronauts have thought it very sensibly diminished ; though we are in clined to suppose, that this opinion may possibly arisen from their inattent,on to the disturbing causes. From an experiment made by the chemist already men tioned, electricity seemed to increase in proportion to the height ; which, he observes, is agreeable to the theory of M. Volta and Saussure. Sacharolf ascertained, that a bell had the same intensity or sound when the barometer fell to 23 inches, as it had at the surface of the earth ; and, when it had sunk to 22 inches, the words spoken downwards from a speaking-trumpet, were re verberated to the ears of the aeronauts, after a lapse of 10 seconds before their return. Some time after the invention of balloons, an experiment was made to ascet tain whether the sound of thunder, rolling among the clouds, was only an echo travelling lrom cloud to cloud, or a succession of distinct explosions. A balloon, five feet in diameter, was prepared by Mr Boulton of Bir mingham, which was furnished with inflammable mate rials to communicate the fire. When sent into the air, accordingly, an explosion took place ; but a shout, at that moment, from the crowd assembled on the occasion, rendered it impossible to distinguish any succeeding explosions. M. Testu, who, in one of his ascents, con tinued for a long time amidst a thunder storm, says, that the hollow sound was very loud but short ; that it was preceded and followed by a hissing or tearing, resem bling the noise of something rending asunder.