5. The Age of Wonder, by Richard Holmes, pp. 114-143

Herschel on the Moon, 8; Balloonists in Heaven, 1-6

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Herschel and his brother Alexander became telescope manufacturers, starting with the five seven-foot reflectors they made for George III as royal gifts. Mirror-making remained hand-crafted, but in the course of a decade they turned out 200 mirrors for the seven-foot telescopes, 150 for the ten-foot, and eighty for the twenty-five-foot telescopes. Their customers were wealthy, and included German princes as well as Napoleon Bonaparte's brother Lucien, the Emperor of Austria, and the King of Spain, who commissioned one for the Madrid Observatory in 1806 that cost £3,500.

Herschel's celebrity attracted visitors to the observatory at Datchet. Samuel Johnson urged Susannah Thrale to visit: "What he has to show is indeed a long way off, and perhaps concerns us little, but all truth is valuable and all knowledge pleasing in its first effects, and may subsequently be useful."

Despite visitors and manufacturing orders, he continued his observations, developing a technique of "sweeping" the sky that consisted of moving "slowly up and down, while the constellations turned through the field of observation as the stars moved steadily across the night sky." It was a highly accurate technique that was also very slow: "A complete sweep could take several years to complete." Herschel's familiarity with the sky, which he could read "like a skilled musician sight-reading a musical score," helped him spot any anomalies in his observations. He also began to write about the process of observation itself, including comments on the nature of the eye.

Caroline compiled his remarks on practical observation. After the move to Datchet in 1782, he began to train her even more into an "assistant-astronomer," responding to William's "imperious shout" whenever he wanted her to write down a new observation. She was expected to respond with military precision to his instructions, and her work was essential: "at no point would William have to compromise his night vision by looking at a lit page and taking his own notes." It was cold and demanding work. "They began at eleven at night, and often did not go to bed before dawn, in a mixed state of exhaustion and euphoria.... Herschel took to rubbing his face and hands with raw onions to keep out the cold.... Caroline layered herself in woollen petticoats."

There were also risks: In the harsh winter of 1783, William was almost blown off of the scaffolding that held his twenty-foot reflector, and the frame collapsed on him so that he had to be rescued from underneath it. In December of that year, Caroline was running to record one of William's observations, tripped on one of the stakes that held the guy ropes for the scaffolding, and impaled herself on the iron hook on top of the stake. It "entered my right leg about six inches above the knee," she wrote later, and the workmen couldn't remove her from the hook "without leaving near 2 oz. of my flesh behind." But they didn't call the doctor: She bandaged the wound herself and was back at work two weeks later. "It seems that the extreme cold had an antiseptic effect on the large, open wound, and prevented fatal gangrene." A week after the accident, Dr. James Lind inspected the wound and prescribed an ointment for it. (Lind was one of Shelley's favorite teachers at Eton.) Though the wound finally healed by summer, Caroline suffered pains from it in old age.

In 1784 and 1785, Herschel "drew together his most radical ideas about the cosmos, and published two revolutionary papers in the Royal Society's Philosophical Transactions." He challenged the idea of a firmly fixed cosmos, and from his study of nebulae "for the first time suggested that many, if not all, of these must be huge independent star clusters or galaxies outside our own Milky Way." As for the Milky Way, "his later calculations produced the now-familiar discus shape ... with its characteristic arms spinning out into space, and the slight bulge of stars at its centre." In "On the Construction of the Heavens," he made the radical observation that "The heavenly 'construction' was not something architecturally fixed by the Creator, but appeared to be constantly changing and even evolving, more like some enormous living organism." His assertions had the effect of "hugely increasing the sense of the actual size of the cosmos."

He began to plan the construction of a forty-foot telescope with a four-foot mirror. And in his 1785 paper for the first time credited Caroline in print as the discoverer of "a small 'associate nebula' in Andromeda."

Meanwhile, as the British were surging ahead in astronomy, the French were making their own advances -- in ballooning. Banks heard about what they were up to in 1783 from Benjamin Franklin, who was a member of the Royal Society as well as the American ambassador to France. The French, he reported, were experimenting with lofting giant paper bags made by a paper manufacturer, Joseph Montgolfier. And then a member of the Académie des Sciences, Alexandre Charles, took things a step further by inflating a silk bag, six feet in diameter, that floated from the Champs de Mars across the Seine and drifted fifteen miles away from Paris before it burst. "This was a distance which a horseman could barely a horseman could barely cover in an hour." Charles's balloon had been filled with a newly discovered gas known as "inflammable air."

Montgolfier recovered from Charles's triumph by sending up a hot-air balloon with a wicker basket that contained a sheep, a duck, and a cockerel. It stayed in the air for seven minutes and the animals returned to earth safely. The logical next step was to send up a human being. Banks was skeptical about the experiments but recognized that they could lead to something useful, such as a "flotation device" that would make carriages and wagons lighter so that horses could pull them faster. "This aptly suggests how difficult it was, even for a trained scientific mind like Banks's, to imagine the true possibilities of flight in those early days."

The "inflammable air" that Charles had used to fill his balloon had been discovered by the English chemists Henry Cavendish and Joseph Priestley. But it was the French chemist Anton Lavoisier who repeated and refined their experiments, producing the gas from iron filings combined with sulfuric acid. He named the product "hydrogen." The Montgolfier brothers, Joseph and Étienne, followed developments in chemistry because of their paper-making business, so when they heard about this lighter-than-air gas, they speculated about using it to fly paper bags. "As early as 1782, Joseph had humorously suggested the theoretical possibility of flying an entire French army into Gibraltar, and seizing it from the English."

The Montgolfiers' first manned flight

The trouble with hydrogen is that "it was slow and dangerous to produce, potentially explosive, and easily escaped from containers made of silk or animal bladders." Hot air was easy to produce and could be contained within silk and paper -- Joseph Montgolfier said he "discovered the principle of hot air by watching his wife's chemise inflating when she hung it over the hearth to dry." The Montgolfiers first large hot air balloon, launched on June 5, 1783, was thirty feet high and 110 feet in circumference. It contained 22,000 cubic feet of hot air, rose to 60,000 feet and stayed up for ten minutes.

A twenty-nine-year-old doctor named Jean-François Pilâtre de Rozier persuaded the Montgolfiers to let him be the "test pilot" in their first manned flight on November 21, 1783. The balloon was seventy feet tall, powered by a brazier burning straw, and had a circular gallery instead of a basket for the passengers. There had to be two of them, one on either side, to balance the balloon. Pilâtre de Rozier's "co-pilot" was the Marquis d'Arlandes, an infantry major. The flight lasted twenty-seven minutes and took them across the Seine.

The launch of Alexandre Charles's hydrogen balloon

But although this was the first manned flight for the record books, the one made ten days later by Alexandre Charles is more significant for its technical breakthroughs. It was a hydrogen balloon whose silk skin had been treated with rubber. It had a valve at the top of the balloon through which the gas could be vented, and ballast bags filled with sand that could be jettisoned to control the balloon's ascent. He and an assistant, M. Robert, went up from the Tuileries Gardens on December 1, 1783.  Benjamin Franklin watched the ascent through a telescope. The flight lasted two hours and traveled twenty-seven miles. When they landed, Charles asked Robert to get out of the basket first, but the release of his weight sent the balloon aloft again, traveling to 10,000 feet in just ten minutes. Charles kept his head, however, and made notes until it grew too cold for him to hold a pen. He slowly released the hydrogen and landed again in thirty-five minutes, only three miles from the original landing spot. "It was the first solo flight in history."

Back in Britain, George III expressed his interest in getting his country into ballooning. Banks was still unconvinced that the French achievements had any practical applications, but he was definitely intrigued. William Watson Jr. had seen one of the unmanned test flights before the Montgolfiers' first manned launch, and excitedly wrote to Herschel about it. Herschel immediately thought about the possibility of using balloons to carry telescopes high into the upper air. Others began to think of the sinister side of ballooning. The novelist Horace Walpole feared the conversion of balloons into "new engines of destruction to the human race."  Benjamin Franklin recognized the military potential of aircraft and calculated that five thousand balloons, each carrying two men, could result in an airborne invasion from France.

But by the summer of 1784, the balloon craze had spread to England. "Unmanned and then manned ascents took place in almost every large city in the kingdom -- London, Oxford, Cambridge, Bristol, Edinburgh." And a twenty-five-year-old Italian, Vincent Lunardi, began to capitalize on the British enthusiasm for balloons. He made his first ascent in London on September 15, 1784, with a crowd of 150,000 as witnesses. "Lunardi drifted north-westwards across London and into Hertfordshire, eating legs of chicken and drinking champagne, and occasionally trying to 'row' his balloon with a pair of aerial oars." But his balloon had no release valve, so he had to try to snag something on the ground with a grappling anchor to end his flight, which he did in a field just outside of Ware.

When he returned to London, "a curiously modern publicity machine began to roll. He sold exclusive rights to his story, and an in-depth interview, to the Morning Post." He was introduced to the king and given a watch by the Prince of Wales, souvenirs of his flight were marketed, and he became the toast of fashionable London. Banks, on the other hand, was unimpressed, and privately referred to Lunardi as "a charlatan." Samuel Johnson was also critical of the hype that surrounded Lunardi, even before the flight, pointing out that buying a ticket to the launch was foolish because "in less than a minute they who gaze at a mile's distance will see all that can be seen." He also expressed skepticism about Lunardi's claim that he would be able to steer the balloon with his oars -- and he was correct. As for ballooning in general, he pointed out that since it couldn't be steered effectively, a balloon failed to "serve any purpose of communication; and it can give no new intelligence of the state of the air at different heights, till they have ascended above the height of mountains, which they seem never likely to do."

Another sensation was caused by Lunardi in June 1785 when he proposed to take the actress Mrs. Sage, who was a rather large woman, and a young man named George Biggin aloft with him. Mrs. Sage was to be the "First Aerial female." But the weight of the three passengers and the elaborate and showy trappings that had been attached to the gondola proved too much for the balloon, so Lunardi jumped out, leaving the two passengers to conduct the flight themselves.

Unfortunately, in his haste to depart, Lunardi failed to do up the lacings of the gondola's door. As the balloon sailed away over Piccadilly, the crowd were treated to the provoking sight of the beautiful Mrs Sage on all fours in the open entrance of the gondola. The crowd assumed that she had fainted, and was perhaps receiving some kind of intimate first-aid from Mr Biggin. 

After Mrs. Sage's flight, cartoonists indulged in ribald speculation

In fact, Mrs. Sage was trying to lace up the door, but when she regained her feet, she stepped on the barometer and broke it, so there was no way to measure how high they flew. So they drifted on, eating cold chicken and drinking Italian sparkling wine, until they landed in a field near Harrow, where they were threatened by an angry farmer and had to be rescued from him by the schoolboys from Harrow School. Afterward, there was ribald speculation about what may have happened between Biggin and Mrs. Sage during the flight. "Gallantly, Mr Biggin refused to comment."

The lack of scientific value of Lunardi's flights became the subject of criticism, and his reputation suffered in 1785 when a young man, Ralph Heron, became entangled in the ropes during a launch at Newcastle, was carried a hundred feet into the air, and fell to his death.