Adolphe Quetelet

Adolphe Quételet

1796 (Ghent, Belgium) – 1874 (Brussels)

Quetelet, an active internationalist, maintained strong links with scientists in several countries. Among these were Babbage, Whewell, Wheatstone, Faraday, Herschel and Airy in Britain, Ampère, Le Verrier and Hachette in France, Gauss, Goethe and Encke in Germany and de la Rive in Switzerland (many contributing to a journal he edited). He studied with Arago, Fourier and Laplace in France, also meeting Poisson, Fresnel and Humboldt. He helped Babbage, Malthus and Whewell establish a Statistical Society, and influenced Nightingale. Marx, living at the same time in Brussels, drew on his work; whether they met is unknown.

Johann Heinrich von Mädler

1794 (Berlin) – 1874 (Hannover)

Mädler attended Humboldt’s lectures while studying at university, gained his attention, and was introduced by him to the wealthy amateur Beer. Beer invited him to join him in using his private observatory; the two produced maps of Mars and the Moon of unprecedented accuracy (Mädler doing most of the hard work). Encke, another of his university teachers, got him an unofficial appointment at the Berlin observatory when Bode (who had also taught him) retired. He showed his Mappa Selenographica to Humboldt and Herschel (and pipped the latter in first using the word ‘photography’), and corresponded with Gauss.

Urbain Le Verrier

1811 (Saint-Lô, France) – 1877 (Paris)

Arago taught Le Verrier, and encouraged the mathematical research that led to his prediction of Neptune’s existence. Le Verrier wrote to Galle, who found the planet after an hour’s observation. Adams had reached the same mathematical conclusion earlier but without publishing the results; public controversy over who was first did not stop Le Verrier and Adams becoming good friends. Arago proposed the new planet be named ‘Leverrier’ (sic) before ‘Neptune’ prevailed, Airy having done what he could to dissuade Le Verrier from the idea, which was in fact his own. Babbage was among Le Verrier’s correspondents.

Pierre-Simon Laplace

1749 (Beaumont-en-Auge, France) – 1827 (Paris)

A letter to d’Alembert on mathematical principles got Laplace a professorship at the École Militaire. He taught Fourier (who however thought Lagrange and Monge better teachers), and encouraged Cauchy. Lagrange was a professional rival, but both gained from the mutual flow of ideas. Laplace and Berthollet founded the influential Société d’Arcueil, whose members included Arago, Poisson, Biot, Gay-Lussac, Malus and Humboldt. With Lavoisier, he showed that respiration was a form of combustion. Biot helped prepare his work for publication, but said that Laplace often forgot his original reasoning, substituting the line “it is easy to see.”

John Couch Adams

1819 (Lidcott, Cornwall, England) – 1892 (Cambridge, England)

Unknown to Adams, Le Verrier had reached the same mathematical conclusions as him about the existence of a new planet (Neptune). Adams had already left a paper with Airy, the Astronomer Royal, asking for observations to be made to test for the predicted planet’s existence, but Airy fatally delayed his response, and when a row erupted over the truth of the discovery of Neptune, cold-shouldered Adams. Le Verrier became a good friend to Adams, despite getting all of the credit. Stokes was a professional collaborator and frequent correspondent; Babbage also corresponded with him.

Jean-Baptiste Biot

1774 (Paris) – 1862 (Paris)

Arago and he worked together early in their careers, Arago coming to feel that Biot had sabotaged his results (he then revenged himself by working with Biot’s protégé Fresnel on the polarisation of light). Assisting Laplace in preparing his findings for publication, Biot observed that Laplace used the stock phrase “it is easy to see” when he’d forgotten his original reasoning. Biot and Gay-Lussac were the first to ascend in a balloon for scientific purposes. He did pioneering electro-magnetic work with Savart, and asked the young Pasteur to come and demonstrate his findings about the handedness of some molecules.

Carl Friedrich Gauss

1777 (Braunschweig, Germany) – 1855 (Göttingen)

Bolyai was a fellow-student, and Gauss’s only real friend — they corresponded for life. Humboldt inspired Gauss’s researches into magnetism, and sought his help towards a global grid of magnetic observatories. His collaboration with Weber led to the first electric telegraph. Jacobi’s youthful work impressed him, and Dedekind, Cantor and Riemann were among his students, though he disliked teaching. Dirichlet carried his ‘Disquisitiones Arithmeticae’ with him all his life. Germain (under a male pseudonym) conducted a substantial mathematical correspondence with him: other correspondents included Bessel and Olbers.

Henry Draper

1837 (Hampden Sydney, Va.) – 1882 (New York)

Draper was a pioneer of astrophotography, despite working at it only part-time. John W. Draper was his father. His younger brother Daniel helped him set up his astronomical observatory. Edison developed a ‘microtasimeter’ for Draper, to measure fluctuations in solar corona temperature during an eclipse (it was over-sensitive).