he never had met them personally, than did another great English physicist, Tyndall, who knew Faraday and Maxwell personally, and one of them at least intimately. In the article in _Nature_, to which Tyndall first referred me and which Maxwell had written, will be found the following closing paragraph: Helmholtz is now in Berlin, directing the labors of able men of science in his splendid laboratory. Let us hope that from his present position he will again take a comprehensive view of the waves and ripples of our intellectual progress, and give us from time to time his idea of the meaning of it all. Helmholtz’s address on Faraday was one of those comprehensive views of which Maxwell spoke in 1874. Now what did Helmholtz see in Faraday and Maxwell which other physicists, like Tyndall, and even so famous a mathematical physicist as Kirchhoff, failed to see? It was, I thought after a careful study of Helmholtz’s address, the simplest thing in the world, particularly for one who, like myself, had been wrestling with Faraday’s lines of force, and with the hypothetical powers with which Faraday had endowed them. So simple, indeed, that I venture to describe it here. But in order to make the description as brief and as simple as possible I must go back again to the charged spherical conductor which always rendered good service in those days when I was trying to solve the riddle of Faraday’s new physical concepts. By means of an electrical force generated by an electrical machine we can increase or diminish the charge on the surface of the conducting sphere. Now, the charge on the sphere increases or diminishes because the electrical force generated by the machine drives through a suitable conducting wire additional electrical charge to the sphere, or takes it away from it. This motion of the electrical charge through the conducting wire to or from the sphere is the electrical current. Here comes now the historic question: Does the electrical current stop at the surface of the charged sphere? The old electrical theories said “Yes,” but Maxwell, interpreting the ideas of Faraday, said, “No.” Helmholtz was the first to tell me that clearly and distinctly, and I understood him.