The interrogator was a twenty-three-year-old from Glasgow named William Thomson, who was already regarded as one of his nation’s leading scientific minds. Years later he, too, vividly recalled the encounter and the feelings of both intrigue and alarm it had evoked: “I felt strongly impelled at first to rise and say that Joule must be wrong,” but “as I listened on and on, I saw that Joule had certainly a great truth and a great discovery, and a most important measurement to bring forward.”
