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.
A notable scientific polymath, Galton was Darwin’s cousin; they corresponded enthusiastically, intrigued by each other’s researches — Galton’s invention of the field of statistical analysis can be said to have had its roots in Darwin’s work. De Candolle was also an influential correspondent, forcing him to reformulate the nature/nurture debate; other correspondents included Wallace (a friend), Stokes, Rayleigh and Maxwell. Herschel taught him the use of an instrument of his own devising; the young Cattell worked alongside him. Hooker, Spencer and Bentham were all friends, while the statistically-minded Nightingale mooted a professorship with him.