LONDON. Royal Society, May 26.—Prof. C. S. Sherrington, president, in the chair.—Sir Alfred Ewing: The atomic process in ferro-magnetic induction. The author's modification of Weber's theory of magnetisation is reconsidered in the light of (1) modern views regarding the structure of the atom and (2) the X-ray analysis of crystal structure. The rotatable Weber magnet seems to be an attribute of the atom, probably an electron system within it. Metallic iron is now known to be an aggregate of crystals, in each of which the space-lattice is the centred cube, with its atoms most closely grouped along the trigonal axes. It is along these axes that the Weber elements will point. Consequently an iron crystal is not magnetically isotropic. The small quasi-elastic or reversible part preceding the much larger changes which involve hysteresis corresponds to a reversible deflection of the Weber magnets through a small angle, generally of an order of i°. The theory of the equilibrium of a row of magnets is considered. Experiments in which rows of Robison magnets with ball ends have their equilibrium upset by an extraneous field confirm the theory. The field which would break up rows of magnets set in the space-lattice close enough together to bring the reversible deflection within the above limit is calculated; it is larger than the field that suffices to produce strong magnetisation in iron, suggesting that the ordinary laws of force between magnetic elements cease to apply at interatomic distances.—C. D. Ellis: The magnetic spectrum of the β-rays excited by the γ-rays. The magnetic spectra of the β-rays ejected from various elements by the y-rays of radium B have been examined by the focussing method. The positions of three strong lines occurring in the magnetic spectrum of radium B depend on the metal target used. Assuming that each of these three lines is due to a definite γ-radiation, it is shown that the energy of the β-rays forming a line is equal to an energy characteristic of the γ-radiation minus the work necessary to remove an electron from the K ring of the atom. By application of the quantum theory the frequency of the γ-rays can be determined from these characteristic energies. The natural β-ray spectrum of radium B can be explained in this way, the stronger lines resulting from the conversion of the γ-rays in the K ring, and the weaker lines from a similar conversion of the same γ-rays in the L ring.—S. Datta: The spectra of the alkaline earth fluorides and their relation to each other. A survey of the spectra of these compounds has been made and several new bands observed. These heloed in the identification of homologous series of bands in the different spectra, and have suggested an empirical relation amongst them, based on the constants of the series equations and the molecular weight or the molecular number of the respective compounds. Starting with the series equation of the band-heads, an explanation has been given of the appearance of a “tail” in some of the ban-ds. It has been shown that the frequency of the “tail” is a maximum or a minimum, and that the difference in wave-numbers of the heads and tails of the similar series is constant for the same compound, but varies from one another in a definite way.—Dr. W. L. Balls: A simple apparatus for approximate harmonic analysis and for periodicity measurements. The error involved in the use of this apparatus need not exceed 3 per cent. Its outstanding advantage is the speed with which determinations may be made. Thus in determinations of periodicity some fifty trial periods can be examined in less time than is required for the computation of a single trial period under the periodogram arithmetical method.—Dr. G. R. Goidshrewgh: The influence of satellites upon the form of Saturn's ring. The ring is supposed to be made up of small particles arranged in concentric circles and rotating about the primary. The satellite is assumed to follow an unperturbed circular orbit, and the influence of the rings upon one another is assumed negligible. To a close degree of numerical approximation the satellite Mimas is responsible for the position and width of Cassini's Division and for the clean-cut termination of the whole ring. Satellite Rhea accounts for the clean-cut commencement of the inner ring (or ring B), while a probable explanation is offered of the existence of the crgpe ring. If m be the mass of any particle, and M the mass of Saturn, and n the number of particles in any single ring, it is shown that