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.