IT was in 1909 that I first came into contact with Rutherford, in my second year in the honours school in Manchester. Owing to some changes in the staff, Rutherford took over a course of lectures on electromagnetism. This was a stimulating experience, for Rutherford was interested in the subject and his account of his own early work remains with me a vivid memory. In our third year some of us were drafted into research work—into the firing line as he would put it—to our great joy and, on occasions, alarm and terror. At that time his main line of work was the study of the properties of the α-particle, already begun in Montreal and continued with increased vigour in Manchester. The counting of the α-particles and the measurement of their charge (both with Geiger) gave a value for the unit of charge which was accepted for some years and showed that the α-particle should be a helium atom. The direct proof followed in the beautiful experiment with Royds. At the same time, the phenomena accompanying the passage of the particles through matter were investigated—the ionization, the ranges of the particles from the different radioactive bodies, the change of velocity and the scattering of the particles.