One of the most influential scientists and mathematicians ever, Newton was a key figure in the scientific revolution. Barrow taught him at Cambridge and recommended him as his own successor. Halley was one of his keenest supporters – his zealous enthusiasm encouraged Newton to publish his Principia Mathematica. Newton met Huygens in London, told his former friend Flamsteed to stick to observation (not theory), and tried to discredit Leibniz (corresponding via Oldenburg as intermediary). He corresponded with Boyle about alchemy, Pepys about gambling odds, and Hooke (whose criticisms hurt) about optics. Cheselden advised against operating when Newton was dying.
Playfair is known, not for original discoveries, but for his clear expounding of theories (especially Hutton’s). Hutton was a close colleague — Playfair, Black and he often spending evenings together, including at the Oyster Club, where other members (and friends of Playfair) included Smith and Ferguson, whom Playfair held a joint professorship with. Playfair encouraged Somerville, investigated Edinburgh geology with Nasmyth, and met his lifelong friend Maskelyne (who got him to publish his first mathematical paper, and introduced him to London colleagues) by visiting and helping with his experimental measuring of mass at Schiehallion.
The amiable Small was inspiring both as a teacher, and as a prime animating force behind the pioneering scientific/industrial Lunar Society. He knew Black and Hutton in Scotland. Franklin, met in Virginia, recommended him to Boulton (Small became his friend, confidant and technical advisor); through Boulton he met Wedgwood, Darwin, Baskerville, Edgeworth and Keir (who loved him affectionately). Small corresponded with Watt, and helped him draft his steam-engine patent. Jefferson credited his teaching for setting him on course for life (and sent him three cases of madeira that sadly arrived after Small’s early death).
A keen anglophile, Lichtenberg met Priestley, Solander, Banks, Aubert and Raspe in London. He went to Drury Lane with Johann Reinhold Forster, admiring and meeting Garrick, and regretted when he visited Bath (bored with tea-drinking and card-playing) that he hadn’t known that his future correspondent Herschel lived there. Goethe and Kant were friends and correspondents, Humboldt a grateful student, and Georg Forster a close friend and fellow-editor. Blumenbach and Gmelin were colleagues in Göttingen. Volta (full of ideas) dedicated a body of research to him: he joked about Volta’s understanding of sexual electricity.
Carlisle deserves to be better-known. Nicholson and he discovered electrolysis after Banks had shown him Volta’s important letter. His recognition of echo-location by bats was a century ahead of its time, he was an early experimenter with winged aviation and involved (with Davy) in Wedgwood’s pioneering photographic experiments, and he helped get child labour legislated against. He studied with Hunter, was doctor to Coleridge, Nollekens and Turner, advised Southey about body-snatching, and as a close friend of Godwin’s attended the dying Wollstonecraft while also very likely being the model for Shelley’s Frankenstein.
The painfully-shy Cavendish was a great ally of Priestley’s in their work on gases, and a regular attender at his friend Banks’ open houses. A leading member of the Royal Society, he was greatly respected by colleagues including Davy (whom he helped), Herschel (a neighbour), and Franklin. He anticipated (without publishing) the findings of many eminent scientists; Wheatstone, Coulomb, Faraday and Ohm among others. Smithson was his lab assistant. Michell (a friend) worked with him to find the earth’s density, but died before completion, Cavendish getting most of the credit. Both Aubert and Maskelyne saw him constantly.
The polymath Young corresponded with Arago and Fresnel about scientific matters in general and the wave theory of light in particular. Arago visited Young in 1816 to tell him of experiments in polarisation he and Fresnel had conducted. Malus and Banks were among his scientific correspondents. Watt, Wilkinson and Young were members of a panel convened to select the design for a new London Bridge. Cavendish and Wollaston were among his friends.
Josiah Wedgwood was Thomas (or Tom) Wedgwood’s father. Both Stubbs and Darwin taught him, Darwin also prescribing the opium to which he later became addicted. Priestley and Watt were friends of Wedgwood’s father’s but with whom he also maintained a correspondence. Southey wrote to Wedgwood about Davy’s nitrous oxide; Davy wrote up Wedgwood’s important photographic image-forming discoveries. Tom and his brother supported Coleridge for most of his adult life, so he could concentrate on writing: Wedgwood and Coleridge were close friends, engaging in passionate intellectual discussion and enthusiastic drug-experimentation.
Black taught Beddoes in Edinburgh: Beddoes complained to him about Oxford’s lack of scientific potential. He met Lavoisier on a trip to Paris. Josiah Wedgwood helped him establish his ‘Pneumatic Institute’, Watt developing equipment for his nitrous oxide experiments, and Darwin, a friend, proposing Bristol for his base. Davy (recommended by Thomas Wedgwood) acted as Beddoes’ assistant, later commenting on his shyness and wild imagination. Coleridge, a close friend, consulted him on his medical problems, imaginary and real. Keir introduced him to R. L. Edgeworth, whose daughter he married: Thomas Lovell Beddoes was their son.
Roget, a polymath and depressive, did much more than invent the thesaurus. He participated in his friend Davy’s laughing-gas experiments though was less than bowled over. Bentham invited him to undertake practical research towards his experimental ice-house, the Frigidarium, though Bentham’s unconventional life proved too much for him. Roget worked with Faraday on experiments that led to his pioneering paper on the persistence of vision. He corresponded with Airy and clashed with Panizzi. Babbage had been a good friend, but they argued endlessly. Talbot invited Roget, along with Wheatstone, Babbage and others, to stay before an important meeting.