Profession: astronomer

The meticulous Airy’s vast correspondence network (many also friends) included Beaufort, FitzRoy, Faraday, Maxwell, Galton, Brunel, Quetelet, Encke, Regnault, Lyell and Owen. He went for long walks with his warm lifetime friend Sedgwick, and visited Southey and Wordsworth in Cumbria, Arago and Laplace in France, and Gauss and Humboldt in Germany. Authoritarian and intolerant of others’ opinions, he had a long and bitter professional argument with Cayley, kept up a running feud with Babbage over everything from telescope design to railway gauges, and effectively terminated funding for his analytical engine.

Lacaille made a huge contribution to mapping the southern-hemisphere stars, proposing constellations with suitably ‘enlightenment’ names. Cassini was a mentor, offering the young Lacaille work, lodging and friendship (he went on to improve some of Cassini’s results). Lalande was a close friend as well as colleague, Clairaut a close colleague, Boscovich a friend. Euler, Mayer and La Condamine were all correspondents of Lacaille’s, and Lavoisier one of his students.

An eminent student of Gauss’s, Encke was recommended by Bessel as head of the Berlin observatory, to succeed Bode. He visited Herschel in England, was helped by Humboldt to get an improved observatory built outside Berlin, and told Gauss, Bessel and Olbers of his great discovery of a comet with an unexpectedly short orbital period. Airy, Babbage and Quetelet were correspondents. Encke only grudgingly allowed his assistant (and former student) Galle to search for a previously unknown planet, but as it was Encke’s birthday, he was otherwise engaged; Galle interrupted the party to tell him the great news.

Zach, an ambitious, well-connected, well-travelled man, established a network of astronomers from the Baltic to the Mediterranean, from England to Poland, leading to the discovery of the Asteroid belt; he also ran significant scientific journals. Olbers, Messier and Gauss (who aged 22 had come to him for instruction) were among the group of astronomers. He taught Humboldt the use of the sextant. He visited Bode in Berlin, Lalande and Laplace in Paris, then Herschel and Banks in London (and rubbed Maskelyne up the wrong way). Pons was his protégé, Śniadecki and Talbot among his widespread correspondents.

The astronomer Olbers (who always kept a ‘day job’ in medicine, and is sometimes known as Heinrich Wilhelm Olbers) and the great mathematician and astronomer Gauss were regular correspondents. Encke told him (and Bessel and Gauss) when he made his momentous discovery of comets with short orbital periods. Struck by the self-taught Bessel’s prodigious talents, Olbers persuaded him to drop the security of his apprenticeship in commerce, and become an astronomer instead.