“Hence then—at all events in this country—scientific men were startled when Arago... published in 1838 the eloge of Watt, which he had read as far back as Dec., 1834, in which he charged Cavendish with deceit and plagiarism, inasmuch as he was said to have learned the composition of water, not by experiments of his own, but by obtaining sight of a letter from Watt to Priestley. The battle now fairly began...”