legend of Virgil undergoes no further modification. Signor Comparetti has collected some allusions from subsequent writers, amongst whom Paracelsus is the most celebrated, which show the later reputation of the poet to have depended on his supposed astrological accomplishments. Here and there were preserved magic mirrors believed to have belonged to him. One such was at Florence in the seventeenth century; Evelyn mentions having seen another at Paris, which perhaps was the one afterwards broken by Mabillon. What amount, if any, of oral tradition may have continued on this subject at Naples since the time of Scoppa, no writer has recorded. That some traces of the kind were remaining at the beginning of the present century is shown by a passage which Signor Comparetti quotes from a German traveller, to whom an old fisherman, while seated on the ruins called the 'Scuola di Virgilio,' narrated many of the well-known legends, and described Virgil as fond of being abroad in a storm with the lightning playing round his head. To the last his influence was believed to have been of a protecting and beneficent character. A recent search for Virgilian traditions produced no noticeable result, except a love song from a contadina near Lecce, in which the lover wishes he had 'the art of Virgil,' that he might bring the sea to the door of his mistress, and take the form of a little fish to be caught in her net, or of a goldfinch, to make his nest in her bosom, and repose at midday in the shadow of her hair. ART. IV.-1. Description des Expériences de la Machine Aérostatique de MM. de Montgolfier. Par M. Faujas de St. Fond. Paris, 1783. 2. Aeronautica. By Monck Mason, Esq. London, 1838. 3. Les Ballons et les Voyages Aériens. Par F. Marion. Paris, 1867. (The same in an English edition.) 4. Voyages Aériens. Par T. Glaisher; Camille Flammarion; W. de Fonvielle; et Gaston Tissandier. Illustrés d'après les croquis d'Albert Tissandier. Paris, 1870. (The same in an English edition, edited by T. Glaisher. London, 1871.) 5. En Ballon, pendant le Siége de Paris. Par Gaston Tissandier. Paris, 1871. 6. Les Ballons dirigeables. Par Gaston Tissandier. Paris, 1872. 7. Reports 7. Reports of the British Association for the Advancement of Science. London, 1862 to 1866. 8. Comptes-rendus des Séances de l'Académie des Sciences. Paris, 1870 and 1872. IT T is an interesting speculation whether man, the creature of the earth, can ever attain to the empire of the air, as he has already attained to the empire of the sea. There is nothing unreasonable in the expectation. As a matter of science the laws that govern the motion of heavy bodies in the atmosphere are sufficiently well known, and as a matter of experience and analogy nothing can be more to the purpose than the example of the birds. Hence there has long been a common belief that we may, some time, be able to transport ourselves at pleasure through the air as we now do on the water. The author of the Botanic Garden,' writing in 1791, when the steam-engine was beginning to develop its wondrous powers, but long before it had been applied to locomotion of any kind, uttered the wellknown prediction— 'Soon shall thy arm, UNCONQUERED STEAM, afar Drag the slow barge, or drive the rapid car; Two-thirds of the prophecy have been fulfilled; he would be a bold man who would pronounce the fulfilment of the remainder impossible. În aerial travelling there are two distinct conditions to be fulfilled. First, there must be a command of vertical motion; the force of gravity must be for the time counteracted, and the heavy body must have a capability of floating, or rising, or falling at pleasure. Secondly, there must, in addition to this, be a power of horizontal translation through the air. Both these effects are well produced by a bird, through the mechanical action of its wings; and hence the most natural attempt at aerial locomotion has been by trying to imitate the bird, or to fly. There is much to be said in favour of this attempt, for although there is little hope that a human being can ever take to himself wings, yet the possibility of constructing a flying machine, if a very light motive power can be obtained, is hardly to be doubted. Hitherto, however, no attempts of this kind have given even a prospect of success; and as our object now is rather to show what has been done than to speculate on what is possible, we will turn to another mode by which aerial locomotion has been more successfully aimed at, namely, by means of the balloon. We propose to trace trace the history of this ingenious invention-to describe its present condition-to dwell on some important purposes it has served and finally to investigate what promise it offers of increased utility. It is not clear when the idea first arose that it would be possible to make a body ascend from the earth by giving it a less specific gravity than the air. One Francis Lana,* in 1670, proposed to exhaust spheres of thin copper for this purpose, but he never attempted to carry out his proposal. The discovery of hydrogen rendered the idea more practicable. Cavendish, in 1766,† showed that the gas known as 'inflammable air' had a specific gravity much less than that of the atmosphere; and Dr. Black, lecturing in 1767 or 1768, explained that, as an obvious consequence of Cavendish's discovery, if a very light bladder were filled with this gas, it would ascend. Tiberius Cavallo attempted the experiment; he could not find any envelope sufficiently light and impermeable, but he succeeded in blowing hydrogen soap-bubbles, which mounted vigorously aloft; and these, the first balloons, were described fully by him in a paper read before the Royal Society, 20th June, 1782.‡ It was not, however, in this way that the balloon came practically into existence; its inventors proceeded on a different principle. Instead of using a new fluid lighter than air, they hit upon the idea of altering the density of the air itself by the action of heat. These ingenious men, Joseph and Étienne Montgolfier, whose names are indissolubly connected with aerostation, were the sons of a rich paper maker at Annonay, in the province of the Vivarais. It seems they were fond of physical investigations: Joseph particularly had studied the constitution of vapour and clouds, and he saw that temperature had much to do with these phenomena. He had convinced himself by experiment that the application of heat would rarefy air so as to reduce its specific gravity considerably, and it occurred to him to try whether, by enclosing such heated air in a suitable envelope, he could make a kind of artificial cloud which would float in the atmosphere. In November 1782, when staying at Avignon, he made the experiment with a light bag of thin silk, which to his great gratification rose to the ceiling. On his return home, the brothers worked together; and after another successful trial they made a public exhibition of their * Prodromo, o saggio di alcune invenzioni nuove, &c. Brescia, 1670. 'Phil. Trans.' vol. lvi. p. 152. The History and Practice of Aerostation.' By Tiberius Cavallo, F.R.S. London, 1785. invention, invention, at a meeting of the États particuliers of the province, on the 5th of June, 1783. Étienne has left on record a description of this first large balloon; it was about thirty-five feet diameter, and had a large ascending power; it rose some thousands of feet, and travelled a mile and a half horizontally. The news of this experiment soon spread to the capital, exciting great wonder and enthusiasm, and the Academy named a Commission to inquire into the facts. But in the meantime attention had become attracted to the other mode of giving levity by hydrogen gas. A young man, named Charles, favourably known as a professor of physics in Paris, had been experimenting with this substance in his laboratory, and conceiving it to have advantages over Montgolfier's heated air, he proposed to substitute it in balloons. He called to his aid two practical mechanicians, the brothers Robert, and constructed a silk balloon of twelve feet diameter. After some difficulty in procuring a sufficient quantity of gas (the manufacture of which, on any large scale, was quite new) it was filled, and transported to the Champ de Mars, where the ascent took place on the 27th of August, 1783. After rising to a great height and travelling many miles, the expansion of the gas caused a small leak in the balloon, and it came down near a village. The inhabitants were frightened beyond measure, particularly when they were told by two monks that it must be some demon from another world. Formal religious exorcisms were recited, but no one dared approach the monster, for the bounds it gave when blown by the wind, the noise of the escaping gas, and its fetid odour, kept up the dread illusion. At length it was fired at, and further wounded, and when it had become empty and still, the mob rushed upon it with staves and forks and tore it to atoms. The Montgolfiers, however, had not been idle. The Academy had reported favourably of their invention, and the brothers were called on to exhibit an ascent before Louis XVI. at Versailles. This came off with great pomp and ceremony on the 19th of September. As the power of balloons had now been fully established, it was proposed that some person should make an ascent, if any one could be found bold enough to face a voyage that required more of the as triplex than the first expedition on the merciless ocean. A volunteer appeared in the person of a young man of good position, named Pilâtre des Roziers, who after making some tentative ascents with the balloon tied to the ground, offered to undertake the journey. It involved some danger: a fall, fire, cold, unknown perils amongst the clouds, and the difficulties of descending, descending, were all matters of grave apprehension; and the King, after consideration, forbade M. de Rozier's ascent, and proposed, instead, that two condemned criminals should take their places in the car. Pilâtre was indignant at the idea of such an honour being conferred on vile malefactors,' and he remonstrated so energetically that the King gave way; and on the 21st of November, 1783, the daring volunteer, accompanied by the Marquis d'Arlandes, left the earth on the first aerial voyage ever undertaken by a human being. A full account of the journey is on record in two documents-one a formal procès-verbal, drawn up by eight members of the Academy, the other a letter by the Marquis. The balloon was seventy feet high, and forty-six feet in diameter; it rose to a height of three thousand feet, remained in the air nearly half an hour, and descended in the environs of Paris, without the aeronauts having experienced the slightest inconvenience. Among the signatures to the procès-verbal was that of Benjamin Franklin, then on a mission to France; and it is reported that when he was asked his opinion of the invention, he replied, 'C'est l'enfant qui vient de naître !' aeronaut. Thus the Montgolfiers not only made the first balloon, but, as was their due, they had the honour of sending up the first The genius and enterprise, however, of their rival, young Charles, soon made themselves apparent by his announcing a personal ascent on his hydrogen principle; and as this principle ultimately became established to the exclusion of the other, Charles's experiments possess the interest of being the more accurate type of our modern aeronautic system. Associating himself again with the Messrs. Robert, he prepared a balloon thirty feet diameter, introducing many important arrangements of detail, which, from their perfection of design and ingenuity of construction, have remained almost unaltered to the present time. The balloon was to ascend on the 1st of December, 1783, from the great basin in front of the Tuileries, and Charles made up his mind to occupy the car; but, while the balloon was filling, it was announced that the King again opposed the proceeding. Charles went to the Minister and protested, declaring that, though his Sovereign might be master of his life, he was not master of his honour, and that he could not break a solemn promise made to the nation. The King yielded to this bold argument, and the prohibition was withdrawn. Shortly afterwards another difficulty arose by a hostile demonstra * The Marquis's letter says 21st October; but it is dated 28th November, it has every appearance of having been written soon after the ascent, and as the procès-verbal gives November, the word October is probably a clerical error. |