tethered aerostats, held to the ground by various ingenious forms of harness, guy ropes or winches.fn5
The poet and inventor Erasmus Darwin’s first practical idea of balloon power was, paradoxically, that of shifting payloads along the ground. He suggested to his friend Richard Edgeworth that a small hydrogen balloon might be tethered to an adapted garden wheelbarrow, and used for transporting heavy loads of manure up the steep hills of his Irish estate. This convenient aerial skip would allow one man to shift ten times his normal weight in earth, but also in bricks or wood or stones. In fact it might cause a revolution in the entire conditions of manual labour.17
Similarly, Joseph Banks, the President of the Royal Society, had the initial idea that balloons could increase the effectiveness of earthbound transport, by adding to its conventional horsepower. He saw the balloon as ‘a counterpoise to Absolute Gravity’ – that is, as a flotation device to be attached to traditional forms of coach or cart, making them lighter and easier to move over the ground. So ‘a broad-wheeled wagon’, normally requiring eight horses to pull it, might only need two with a Montgolfier attached. This aptly suggests how difficult it was, even for a trained scientific mind like Banks’s, to imagine the true possibilities of flight in these early days.18
Benjamin Franklin, ‘the old fox’, as Banks’s secretary Charles Blagden called him, was quick to suggest various menacing military applications, perhaps in a deliberate attempt to fix Banks’s attention. ‘Five thousand balloons capable of raising two men each’ could easily transport an effective invasion army of ten thousand marines across the Channel, in the course of a single morning. The only question, Franklin implied, was which direction would the wind be blowing from?19
His other speculations were more light-hearted. What about a ‘running Footman’? Such a man might be suspended under a small hydrogen balloon, so his body weight was reduced to ‘perhaps 8 or 10 Pounds’, and so made capable of running in a straight line in leaps and bounds ‘across Countries as fast as the Wind, and over Hedges, Ditches & even Water …’ Or there was the balloon ‘Elbow Chair’, placed in a beauty spot, and winching the picturesque spectator ‘a Mile high for a Guinea’ to see the view.
There was also Franklin’s patent balloon icebox: ‘People will keep such Globes anchored in the Air, to which by Pullies they may draw up Game to be preserved in the Cool, & Water to be frozen when Ice is wanted.’20 This contraption would surely have appealed to the twentieth-century illustrator W. Heath Robinson.
Franklin, who suffered formidably from gout, later suggested that a balloon might even be used to power a wheelchair. When he had returned from Paris to Philadelphia in autumn 1785, he began using a sedan chair lifted by four stout assistants for his daily commute from his house to the Philadelphia State Assembly Rooms. He suggested reducing the requisite manpower by 75 per cent, simply by harnessing the chair to a small hydrogen balloon, ‘sufficiently large to raise me from the ground’. This would make his malady less vexatious for all concerned, by providing a ‘most easy carriage’, lightweight and highly manoeuvrable, ‘being led by a string held by one man walking on the ground’.21 fn6
8
In 1785 Tiberius Cavallo, a Fellow of the Royal Society, put together the first British study of ballooning. His A Treatise on the History and Practice of Aerostation studiously adopted the French scientific term for ‘lighter-than-air’ flight, but moved far beyond national rivalries. He wanted to consider the phenomenon of flight from both a scientific and a philosophical point of view. He thought that ballooning held out immense possibilities, less as a transport device than as an instrument for studying the upper air and the nature of weather. This distinction between horizontal and vertical travel would have a long subsequent history.
Cavallo was a brilliant Italian physicist who had moved to London at the age of twenty-two, and had already written extensively on magnetism and electrical phenomena. Elected to the Royal Society in 1779, he quickly turned his attention to ballooning. He had some claims to be one of the first to inflate soap bubbles with hydrogen as early as 1782. Although a handsome portrait is held by the National Portrait Gallery in London, he is now largely and unjustly forgotten. Yet his study emerges as the most authoritative early treatise on the subject of ballooning in either English or French. The copy of Cavallo’s book held by the British Library is personally inscribed ‘To Sir Joseph Banks from the Author’, in severe black ink.
Cavallo carefully adopted a considered and even sceptical tone, well calculated to appeal to Banks. Much had been made of Vincenzo Lunardi’s historic first flight in Britain, in September 1784, when he flew from London to Hertfordshire with his pet cat. The newspapers of the day all declared Lunardi a heroic pioneer, a patriot and an animal lover, although the gothic novelist Horace Walpole – author of The Castle of Otranto – roundly criticised him for risking the life of the said cat. But Cavallo noted: ‘Besides the Romantic observations which might be naturally suggested by the Prospect seen from that elevated situation, and by the agreeable calm he felt after the fatigue, the anxiety, and the accomplishment of his Experiment, Mr Lunardi seems to have made no particular philosophical observation, or such as may either tend to improve the subject of aerostation, or to throw light on any operation in Nature.’23 fn7
Cavallo analysed and dismissed most claims to navigate balloons, except by the use of different air currents at different altitudes.24 He emphasised the aeronaut’s vulnerability to unpredictable atmospheric phenomena such as down-drafts, lightning strikes and ice formation. He deliberately included the first alarming account of a French balloon caught in a thunderstorm, during an ascent from Saint-Cloud in July 1784, and dragged helplessly upwards by a thermal:
Three minutes after ascending, the balloon was lost in the clouds, and the aerial voyagers lost sight of the earth, being involved in dense vapour. Here an unusual agitation of the air, somewhat like a whirlwind, in a moment turned the machine three times from the right to the left. The violent shocks, which they suffered prevented their using any of the means proposed for the direction of the balloon, and they even tore away the silk stuff of which the helm was made. Never, said they, a more dreadful scene presented itself to any eye, than that in which they were involved. An unbounded ocean of shapeless clouds rolled one upon another beneath, and seemed to forbid their return to earth, which was still invisible. The agitation of the balloon became greater every moment … 25
Yet for all this, Cavallo was a passionate balloon enthusiast. He recorded and analysed all the significant flights, both French and English, made from Montgolfier’s first balloon at Annonay in June 1783, to Blanchard and Jeffries’s crossing of the Channel in January 1785. He distinguished carefully between hot-air and hydrogen balloons, and their quite different flight characteristics. He looked in detail at methods of preparing hydrogen gas, noting that Joseph Priestley had come up with one that used steam rather than sulphuric acid. He also examined the different ways of constructing balloon canopies from rubber (‘cauchou’), waxed silk, varnished linen and taffeta.
In a longer perspective, he stressed the astonishing speed of aerial travel over the ground – ‘often between 40 and 50 miles per hour’ – combined with its incredible ‘stillness and tranquillity’ in most normal conditions.26 This he thought must eventually revolutionise our fundamental ideas of transport and communications, even if the moment had not yet arrived. But he was less impressed by the horizontal potential of ballooning than by its vertical one. The essence of flight lay in attaining an utterly new dimension: altitude.
He
