The Invention of Nature

The East India Company might have been uncooperative but it seemed that everybody else in Britain was enthusiastic about Humboldt. Many of the British scientists whom he had met in London now visited him in Paris. The famous chemist Humphry Davy came again, as did John Herschel, the son of astronomer William Herschel, and Charles Babbage, the mathematician hailed today as the father of the computer. Humboldt ‘derived pleasure from assisting’, Babbage said, no matter how famous or unknown the caller. Oxford geologist William Buckland was equally excited to meet Humboldt in Paris. Never had he heard a man talk faster or with more brilliance, Buckland wrote to a friend. As always, Humboldt was generous with his knowledge and collections, opening his cabinet and notebooks to Buckland.

One of the most significant scientific encounters was with Charles Lyell, the British geologist whose work would help Charles Darwin shape his ideas about evolution. Fascinated by the formation of the earth, Lyell had travelled across Europe in the early 1820s to investigate mountains, volcanoes and other geological formations for his revolutionary work, Principles of Geology. Then, in the summer of 1823, around the same time as news of Bonpland’s imprisonment had reached Bolívar, an enthusiastic twenty-five-year-old Lyell went to Paris with his bags full of introductory letters to Humboldt.

Since his return from Latin America, one of Humboldt’s projects had been to collect and compare data on rock strata across the globe. After almost two decades he had finally published the results in his Geognostical Essay on the Superposition of Rocks, just a few months before Lyell reached Paris. This was exactly the kind of information Lyell needed for his own research. The Geognostical Essay, Lyell wrote, was ‘a famous lesson to me’. It would have placed Humboldt in the highest ranks of the science world, he believed, even if he published nothing else. During the next two months, the two men spent many afternoons together, talking about geology, Humboldt’s observations at Mount Vesuvius and mutual friends in Britain. Humboldt’s English was excellent, Lyell noted. ‘Hoombowl’, Lyell wrote to his father – the way Humboldt’s French servant pronounced his name – gave him plenty of material and useful data.

They also discussed Humboldt’s invention of isotherms, the lines that we see on weather maps today and which connect different geographical points around the globe that are experiencing the same temperatures.¹ Humboldt had come up with the design for his essay On the Isothermal Lines and the Distribution of Heat on the Earth (1817) in order to visualize global climate patterns. The essay would help Lyell to form his own theories, and also marked the beginning of a new understanding of climate – one on which all subsequent studies about the distribution of heat were based.

Until Humboldt’s isotherms, meteorological data had been collected in long tables of temperatures – endless lists of different geographical places and their climatic conditions which gave precise temperatures but were difficult to compare. Humboldt’s graphic visualization of the same data was as innovative as it was simple. Instead of confusing tables, one look at his isotherm map revealed a new world of patterns that hugged the earth in wavy belts. Humboldt believed that this was the foundation of what he called ‘vergleichende Klimatologie’ – comparative climatology. He was right, for today’s scientists still use them to understand and depict climate change and global warming. Isotherms enabled Humboldt, and those who followed, to look at patterns globally. Lyell utilized the concept to investigate geological changes in relation to climatic changes.

Map showing isotherms (Illustration Credit 14.1)

The central argument of Lyell’s Principles of Geology was that the earth had been shaped gradually by minute changes rather than by sudden catastrophic occurrences such as earthquakes or floods as other scientists thought. Lyell came to believe that these slow forces were still active in the present day which meant that he had to look at the current conditions in order to learn about the past. To argue his case for the influence of gradual forces, and to move scientific thinking away from the more apocalyptical theories of the earth’s beginning, Lyell had to explain how the surface of the planet had cooled gradually. He ‘read up’ on Humboldt, Lyell later told a friend, while working on his own theory.