Jean le Rond d’Alembert

1717 (Paris) – 1783 (Paris)

Key player in the French Enlightenment. Diderot and d’Alembert were co-editors of the Encyclopédie, Rousseau as well as Buffon a noted contributor, and Voltaire one of the project’s greatest supporters. D’Alembert encouraged Monge to submit papers to the Académie des Sciences, helped the mathematicians Legendre, Condorcet and Lagrange up the professional ladder, but was put out to feel that Laplace’s subsequent work made his own obsolete. Hume, Smith and Gibbon were fellow attendees at d’Holbach’s salon. Rameau had been a friend, but disagreements over the Encyclopédie soured their relations. Casanova described him as the most modest man he’d ever known.

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.

James Clerk Maxwell

1831 (Edinburgh) – 1879 (Cambridge, England)

Tait was a schoolfriend, in fact a friend for life. At 23, Maxwell famously provided the mathematical theorisation of Faraday’s more empirically-based electromagnetic work (though it overshadows all else, this was far from his only significant achievement). Thomson and Stokes were friends and mathematical-physics colleagues. He corresponded with Wheatstone on telegraphy, sent Gibbs a plaster model after reading his paper on the 3D representation of thermodynamics, and was a friend of Babbage’s. Airy also corresponded; he described a paper of Maxwell’s as “one of the most remarkable applications of mathematics to physics” he’d ever seen.

Jacques Roubaud

1932 (Caluire-et-Cuire, France) –

Queneau, Le Lionnais, Bénabou and Perec were all friends and colleagues in the experimental writing group Oulipo. Paz, Sanguinetti and Roubaud collaborated (with an English poet) on a four-handed quadrilingual poem.

George Stokes

1819 (Skreen, Ireland) – 1903 (Cambridge, England)

Stokes corresponded with Wheatstone on the chemistry of colour. Maxwell, as well as Thomson, became a friend and colleague at Cambridge; they collaborated for over 50 years. Thomson personally benefited from Stokes’ sharing of his ideas about spectroscopy, and pointed out that several important discoveries of Stokes’ were uncreditied to him as he’d never formally published them. Adam, Owen, Crookes, Tait, Herschel and Airy were among his frequent scientific correspondents.

Gaspard Monge

1746 (Beaune) – 1818 (Paris)

Monge was something of a protégé of Bossut’s. Condorcet and d’Alembert encouraged him to submit research papers to the Académie des Sciences. He taught Malus and Hachette as well as Fourier, who described him as very learned, and having a loud voice. Berthollet, an intimate friend, accompanied him on Bonaparte’s expedition to Egypte, where with Malus and Fourier he became a member of the Institut d’Égypte. Monge collaborated with Lavoisier, and visited his friend Lagrange when the latter was dying.

François Le Lionnais

1901 (Paris) – 1984 (Paris)

He met Duchamp and Roussel through his chess obsession, and founded a science-writers’ group with de Broglie. Queneau and he were both pataphysicians, and formed Oulipo initially as a spin-off. Berge, Arnaud, Roubaud, Perec and Bénabou all became Oulipians. The last three were initially shocked at what the infirm Le Lionnais charged them for round-table dinners, but grew warmer, Perec spending several days dusting and sorting his books. He sniffed out Freymann, who published books on aspects of mathematics and other interesting subjects that no-one else would, and introduced Queneau to him.

Augustin Louis Cauchy

1789 (Paris) – 1857 (Sceaux, France)

Cauchy’s father’s friend Lagrange advised studying languages before specialising in mathematics; Laplace also encouraged him. He was a student of Ampère’s, and was encouraged by Legendre and Malus in his work on polygons and polyhedra. When Biot went on an expedition to Shetland, Cauchy stepped into his shoes. The revolutionary firebrand Galois sent a paper to the difficult and ultra-conservative Cauchy, who nonetheless encouraged him to send it on to Fourier. He cold-shouldered Poncelet, and met Bolzano (according to a letter of the latter’s) when he went to Prague to coach the emperor’s unresponsive son.

Alexis Clairaut

Alexis Clairault

1713 (Paris) – 1765 (Paris)

Clairaut joined his good friend Maupertuis’ year-long expedition to Lapland to determine the Earth’s true shape, though later the two fell out. A friend of Voltaire and Châtelet, he helped Châtelet translate Newton into French. Visiting Bernoulli with Maupertuis, he befriended König and started collaborating with him. Maclaurin was among Clairaut’s mathematical correspondents. Euler – who corresponded for 24 years – wrote in support of his lunar orbital calculations. A former prodigy himself, Clairaut praised the 16-year-old Condorcet’s mathematical abilities.