There remained only the hope that some means might be found of buoying man up in the air, thereby leaving him free to apply his muscular and mechanical powers to the business of driving himself forward. Another celebrated treatise of the seventeenth century pointed the way to such a means. Francesco Lana, a member of the Society of Jesus in Rome, spent the greater part of his life in scientific research. He planned a large encyclopaedia, embodying all existing science, in so far as it was based on experiment and proof. Of this work only two volumes appeared during his lifetime; he died at Brescia in the year 1687. But long before he died, he had produced, in 1670, a preliminary sketch of his great work; and it is this earlier and shorter treatise which contains the two famous chapters on the Aerial Ship. The aerial ship is to be buoyed up in the air by being suspended from four globes, made of thin copper sheeting, each of them about twenty-five feet in diameter. From these globes the air is to be exhausted, so that each of them, being lighter than air, will support the weight of two or three men. The ship being thus floated can be propelled by oars and sails.
Any modern reader, without asking for further specifications, can pronounce this design absurd. Lana was prevented by his vow of poverty from spending any money on experiment, so that he had to meet only argumentative objections, not those much more formidable obstacles, the ordeal of the inventor, which present themselves when a machine is theoretically perfect and will not work. The difficulties which he foresaw are real enough. The process of exhausting the air from the globes might, he thought, prove troublesome. The pressure of the atmosphere on the outer surface, it might be held, would crush or break the globes, to which he replied that that pressure would be equal on all sides, and would therefore rather strengthen the globes than break them. The ship, some might object, could not be propelled by oars; Lana thinks it could, but suggests, to comfort the objectors, that oars will rarely be necessary, for there will always be a wind. The weight of the machine and of the persons in it will fortunately prevent it from rising to heights where breathing becomes impossible. 'I do not foresee', says Lana, 'any other difficulties that could prevail against this invention, save one only, which to me seems the greatest of them all, and that is that God would never surely allow such a machine to be successful, since it would create many disturbances in the civil and political governments of mankind. Where is the man who can fail to see that no city would be proof against surprise, when the ship could at any time be steered over its squares, or even over the courtyards of dwelling-houses, and brought to earth for the landing of its crew?... Iron weights could be hurled to wreck ships at sea, or they could be set on fire by fireballs and bombs; nor ships alone, but houses, fortresses, and cities could be thus destroyed, with the certainty that the airship could come to no harm as the missiles could be hurled from a vast height.'
The extravagance of Lana's design must not be allowed to rob him of the credit of being, in some sense, the inventor of the balloon. A balloon filled with gas, and lighter than air, was in his day inconceivable; the composition of the atmosphere was unknown, and the chemistry of gases was not understood. But he had followed the physical investigations of the seventeenth century, and was well acquainted with Torricelli's demonstration of the weight of the atmosphere. The only practical way for him to make a vessel lighter than air was to empty it of the air within it, and Torricelli's invention of the barometer seemed to bring such a device within reach. The common pump begat the barometer; the barometer begat the balloon. But the enormous pressure of the atmosphere on a vessel encasing a vacuum, though Lana had triumphed over it in argument, could not be so easily dealt with in practice. The success of the balloon was delayed until, by the discovery and production of a gas lighter than air, a frail and thin envelope could be supported against the pressure from without by an equal pressure from within.
For ballooning what was chiefly necessary was a thorough knowledge of gases and of the means of producing them. The older chemistry, or alchemy, devoted all its attention, for centuries, to the precious metals, and knew nothing of gas. Medical chemistry, which succeeded it, was concerned chiefly with the curative properties of various chemical preparations. When Robert Boyle, and the investigators who came after him, put aside this age-long preoccupation with wealth and healing, and set themselves to determine, by observation and experiment, the nature of common substances, and the possibility of resolving them into simpler elements, modern chemistry began. Four states of matter, namely, earth, air, fire, and water, were recognized by the older chemists, and were by them called elements; it was the work of the eighteenth century to investigate these, and especially to separate the constituents of air and of water. In 1774 Joseph Priestley discovered oxygen. In 1782 Henry Cavendish showed that hydrogen, when burnt, produces water. At a much earlier date hydrogen had been produced by the action of acid on metals, and had been found to be many times lighter than air. Dr. Joseph Black, professor of chemistry in the University of Edinburgh, was the first to suggest, in 1767, that a balloon inflated with hydrogen would rise in the air; and the experiment was successfully tried with soap-bubbles by Tiberius Cavallo, in the year 1782.
Nevertheless, the famous first balloon, which ascended in 1783, was not filled with hydrogen, and was invented by what may be called a happy accident. The brothers Joseph and Jacques Montgolfier were the sons of a wealthy paper-maker at Annonay, not very far from Lyons. The suggestion of their balloon came to them from observing that thick opaque clouds float high in the air. Linen material was readily accessible to them at the factory, and they resolved to try whether a large balloon, some thirty-three feet in diameter, filled with smoke vapours, would rise in the air. Their experiment was successful. On the 5th of June 1783 they filled their balloon with smoke (and therefore with hot air) over a fire of chips and shavings; it rose easily, and travelled to a distance of about a mile and a half before it cooled and sank. The fame of this experiment quickly reached Paris, the centre of science and fashion, and awakened rivalry. Under the direction of Professor Charles, a well-known physicist, two brothers whose surname was Robert made from varnished silk a balloon of about thirteen feet in diameter; it was filled with hydrogen, and on the 27th of August 1783, in the presence of a large and excited assembly, it rose from the Champ de Mars and travelled some fifteen miles into the country, where it fell, and produced a panic among the peasantry. On the 19th of September Joseph Montgolfier was brought to Versailles to give a demonstration of his new invention in the presence of the King and Queen. On this occasion his balloon rose 1,500 feet into the air, carrying with it a sheep, a cock, and a duck, the first living passengers, whom it deposited unhurt when it came to ground again after a short flight. Thereafter society went balloon-mad. Pilâtre de Rozier, a young native of Metz, determined to attempt an aerial voyage. During the month of October he experimented with a captive balloon of the Montgolfier type, from which he suspended a brazier, so that by a continued supply of heated air the balloon should maintain its buoyancy. On the 21st of November 1783, accompanied by the Marquis d'Arlandes, he rose in a free balloon from the Bois de Boulogne, and made a successful voyage of twenty minutes, during which time he travelled over Paris for a distance of about five miles. Ten days later, on behalf of the savants, M. Charles retorted with a voyage of twenty-seven miles, in a hydrogen balloon, from Paris to Nesle; he was accompanied by one of the brothers Robert, and when Robert left the car at Nesle the balloon, lightened of a part of its burden, rose rapidly with M. Charles to a height of two miles in the air. Most of the fittings of the modern hydrogen balloon, the hoop and netting, for instance, from which the car is suspended, and the valve at the top of the balloon for the release of the gas, were devised by Charles. The unfortunate Pilâtre de Rozier met his death on the 15th of June 1785, in an attempt to cross from Boulogne to England. In order to avoid a constant wastage of hydrogen in controlling the height of the balloon, he devised a double balloon; the larger one, above, was filled with hydrogen, the smaller one, below, was worked with hot air from a brazier, on the Montgolfier principle. At a height of some three thousand feet, while it was still over French territory, the double balloon caught fire and fell flaming to the earth.
The earliest balloon ascents in England followed close upon the French experiments. On the 25th of November 1783 Count Francesco Zambeccari sent up an oil-silk hydrogen balloon, ten feet in diameter, from the Artillery Ground in Moorfields; it travelled forty-eight miles, and fell at Petworth in Sussex. On the 22nd of February 1784 a balloon of five feet in diameter, liberated at Sandwich in Kent, travelled seventy-five miles, and after crossing the Channel, fell at Warneton in Flanders. To inflate a bag with gas and let it take its chance in the air is no great achievement, but these were flights of good promise. The first person in Great Britain to navigate the air was James Tytler, a Scot, who on the 27th of August 1784 ascended in a fire-balloon, that is, a balloon filled with hot air, from Comely Gardens, Edinburgh, and travelled about half a mile. Tytler had been employed by the booksellers to edit the second edition of the Encyclopaedia Britannica, of which he wrote the greater part, at a salary of seventeen shillings a week; he passed his life in poverty, and his balloon adventure attracted little attention. The public mania for ballooning as a spectacle began with the ascents of Vincenzo Lunardi, secretary to the Neapolitan ambassador in England. Lunardi's first ascent, which was well advertised, was made from the Artillery Ground in Moorfields on the 15th of September 1784, in the presence of nearly two hundred thousand spectators. His hydrogen balloon, of about thirty-two feet in diameter, sailed high over London, and descended near Ware in Hertfordshire. His record of his sensations, written in imperfect English, and published in 1784 under the title of An Account of the First Aerial Voyage in England, deserves quotation:
'At five minutes after two, the last gun was fired, the cords divided, and the Balloon rose, the company returning my signals of adieu with the most unfeigned acclamations and applauses. The effect was that of a miracle on the multitudes which surrounded the place; and they passed from incredulity and menace into the most extravagant expressions of approbation and joy.
'At the height of twenty yards, the Balloon was a little depressed by the wind, which had a fine effect; it held me over the ground for a few seconds, and seemed to pause majestically before its departure.
'On discharging a part of the ballast, it ascended to the height of two hundred yards. As a multitude lay before me of a hundred and fifty thousand people, who had not seen my ascent from the ground, I had recourse to every stratagem to let them know I was in the gallery, and they literally rent the air with their acclamations and applause. In these stratagems I devoted my flag, and worked with my oars, one of which was immediately broken and fell from me. A pigeon too escaped, which, with a dog, and cat, were the only companions of my excursion.
'When the thermometer had fallen from 68° to 61° I perceived a great difference in the temperature of the air. I became very cold, and found it necessary to take a few glasses of wine. I likewise eat the leg of a chicken, but my bread and other provisions had been rendered useless by being mixed with the sand which I carried as ballast.