Nuclear physics dominated the agenda of an International Conference on Physics, that began in London at the Royal Institution on 2 October 1934. Rutherford opened the gathering with a survey titled simply ’Opening Survey’ [12-1]. He was followed, somewhat later, by papers read by Joliot, reporting on their work in Paris on artificial radioactivity via (a, n) reactions followed by delayed positron emission, by Enrico Fermi on their own program on radioactivity induced by neutron bombardment, and finally by Robert Millikan, who dwelt on cosmic rays. Fermi had correctly supposed that neutrons, carrying no electric charge, were more effective than a-particles in initiating nuclear reactions. His appearance in London, it might be noted, was less than three weeks before he and his colleagues at the University of Rome made a singularly important discovery, of the effectiveness of slow neutrons in provoking nuclear reactions and artificial radioactivity by (n,7) reactions. By a curious twist, while he was still in London his partners Edorado Amaldi and Emilio Segre had searched with contradictory results for signs of the (n, 7) irradiation of aluminum, and so cabled Fermi, who was ’angered and embarrassed at having communicated an erroneous result.’ He need not have fretted, as it turned out [12-2].