It was one of the most foolhardy flights in history, and only a stroke of luck at 37,000ft prevented them drifting up to their deaths at the edge of the atmosphere.
The dead pigeons should have been James Glaisher’s warning. On 5 September 1862, the scientist was taking one of his first balloon flights – and alongside the compass, thermometers and bottles of brandy, he had decided to bring along six birds.
“One was thrown out at the height of three miles. When it extended its wings it dropped like a piece of paper; the second, at four miles, flew vigorously round and round, apparently taking a dip each time; a third was thrown out between four and five miles, and it fell downwards as a stone”.
No sooner had he noted these observations than he began to feel the “balloon sickness” himself. His arm had been resting on the table, but it failed to respond when he tried to lift it. Alarmed, he tried to call out to his aeronaut, Henry Coxwell, but the words froze in his mouth and his head lolled helplessly to one side.
Glaisher knew the end was nigh. “In an instance darkness overcame me… I believed I would experience nothing more as death would come unless we speedily descended.”
As they rose beyond five miles, however, the temperature dropped below -20C, and he began to notice difficulties with his vision. “I could not see the fine column of the mercury in the wet-bulb thermometer; nor the hands of the watch, nor the fine divisions on any instrument.” Clearly, they needed to descend – yet the balloon’s valve-line had become entangled in the other ropes. Coxwell had to climb out of the basket to release it, but while he was dangerously clambering among the rigging, Glaisher was slowly losing consciousness.
Up on the ring, Coxwell felt that he too was losing control of his limbs. Realising that his life was at risk, he grabbed hold of the valve-line with his teeth and yanked his head several times. To his immense relief, it opened and they began their descent. Glaisher awoke to hear Coxwell muttering vaguely above him. “I have been insensible,” he said – but wasted no time in returning to his experiments. “I then drew up my legs and took a pencil to begin observations,” he recorded in the book Travels in the Air. Of the pigeons, only one remained with them by the time they had reached the ground. It seemed so traumatised by the experience that it clung to Glaisher’s hand for 15 minutes before taking flight.
The pair estimated that they had risen to 37,000 feet – 7 miles (11km) – the highest altitude that a manned flight had reached at that point.