The Invention of Nature

Humboldt was passed on from one person to another – politicians, scientists and a ‘force of noblemen’. At the Royal Society, Humboldt met his old friends John Herschel and Charles Babbage, and attended a meeting during which one of the fellows presented ten maps that were part of a new atlas of India which had been commissioned by the East India Company – a painful reminder of what Humboldt was missing. He had dinner with Mary Somerville,⁴ one of the few female scientists in Europe, and visited the botanist Robert Brown at the botanic garden at Kew just to the west of London. Brown had explored Australia as one of Joseph Banks’s plant collectors, and Humboldt was keen to learn about Antipodean flora.

Humboldt was also invited to an elegant party at the Royal Academy and dined with his old acquaintance George Canning, who just two weeks previously had become the British Prime Minister. At Canning’s dinner, Humboldt was delighted to meet his old friend from Washington, DC, Albert Gallatin, who was now the American Minister in London. Only the attention of the British aristocracy annoyed Humboldt. Paris was a sleepy town compared to ‘my torments here’, he wrote to a friend, because everybody seemed to want a piece of him. In London ‘every sentence begins’, he complained, with ‘you will not leave without having seen my country-house: it is only 40 miles from London.’

Humboldt’s most exciting day, however, was spent not with scientists or politicians but with a young engineer, Isambard Kingdom Brunel, who had invited Humboldt to observe the construction of the first tunnel under the Thames. The idea of building a tunnel under a river was as daring as it was dangerous, and no one had ever succeeded in doing such a thing.

The conditions at the Thames could not have been worse because the riverbed and the ground beneath consisted of sand and soft clay. Brunel’s father, Marc, had invented an ingenious method of building the tunnel: a cast-iron shield in the height and width of the tunnel tube. Inspired by a shipworm that bored through the toughest timber planks by protecting its head with a shell, Marc Brunel had designed a huge contraption that allowed the excavation of the tunnel while at the same time propping up the ceiling and keeping the soft clay in place. As the workers moved the metal shield in front of them under the riverbed, they built up the tunnel’s brick shell behind them. Inch by inch, and foot by foot, the length of the tunnel slowly grew. Work had begun two years previously and by the time Humboldt came to London Brunel’s men had reached about the halfway point of the 1,200-foot-long tunnel.

The work was treacherous and Marc Brunel’s diary was filled with thoughts of worry and concern: ‘anxiety increasing daily’, ‘things are getting worse every day’, or ‘every morning I say, Another day of danger over.’ His son Isambard, who had been made ‘resident engineer’ in January 1827 at the age of twenty, brought his boundless energy and confidence to the project. But the work was challenging. In early April, shortly before Humboldt arrived, more and more water seeped into the tunnel and Isambard had forty men pumping to keep the influx of water under control. There was only ‘clayey silt above their heads’, Marc Brunel worried, fearing that the tunnel could collapse at any moment. Isambard wanted to inspect the construction from the outside and asked Humboldt to join him. It would be dangerous but Humboldt didn’t care – this was too exciting to miss. He also hoped to measure the air pressure at the bottom of the river to compare it to his observations in the Andes.

The diving bell in which Humboldt descended with Brunel to the bottom of the Thames to see the construction of the tunnel (Illustration Credit 14.2)

On 26 April a huge metal diving bell that weighed almost two tons was lowered by a crane from a ship. Boats filled with curious onlookers crowded the surface of the river as the diving bell with Brunel and Humboldt inside was dropped to a depth of thirty-six feet. Air was supplied through a leather hose that was inserted at the top of the bell, and two thick glass windows offered views into the murky river water. As they descended, Humboldt found the pressure in his ears almost unbearable but he got used to it after a few minutes. They wore thick coats and looked like ‘Eskimos’, Humboldt wrote to François Arago in Paris. Down on the riverbed with the tunnel below them and only water above, it was eerily dark except for their lanterns’ weak glimmer. They spent forty minutes underwater but as they ascended the changing water pressure ruptured blood vessels in Humboldt’s nose and throat. For the next twenty-four hours he spat and sneezed blood, just as he had when climbing Chimborazo. Brunel didn’t bleed, Humboldt noted, and joked that it was seemingly ‘a privilege of Prussians’.