Abstract
LONDON Royal Society, February 23.—Sir Charles Sherrington, president, in the chair.—C. D. Ellis: β-Ray spectra and their meaning. A method of finding the wave-lengths of γ-rays of too high a frequency to be measured by the crystal method depends on the fact that γ-rays are converted into β-rays according to the quantum relation. If the energies of the groups of electrons ejected by γ-rays be added to the work done in removing the electron from inside the atom to the surface, hv is obtained. The work is found from observations of the energies of corresponding groups excited in different substances, and the method is applied to find the wave-lengths of the γ-rays emitted by radium B, radium C, and thorium D. The energies of the β-ray groups of thorium D have been measured for this purpose. The γ-rays are emitted from the nucleus and the numerical values of the wave-lengths suggest that the quantum dynamics applies to the nucleus and that part of the structure can be expressed in terms of stationary states. Suggestions for the energy of these stationary states in radium B and thorium D nuclei are given.—A. E. Conrady: A study of the balance. The first weighings by the Gaussian method of exchange made with an inexpensive analytical balance gave a probable error of only 0.004 mg. A constructional fault in the suspensions was remedied and the probable error fell to 0.0013 mg. A further systematic error, depending on the sequence of pointer readings in successive exchanges was attributed to imperfect elasticity and irregular curvature of knife-edges. A method of double exchange of loads which, by close adjustment of a light rider, caused all readings to fall on two alternating positions of rest, brought the probable error to 0.0008 mg., and it seemed now largely due to irregular air-currents. Arrangements allowing manipulation of loads without opening of balance case reduced the probable error to an average value of 0.0004 mg. If the centre of gravity of the moving parts falls in the supporting line of the central knife-edge (“autostatic” state), the reading of the pointer becomes independent of levelling of the balance case, and highly accurate results can be obtained on very infirm supports.—J. S. Owens: Suspended impurity in the air. The essential part of a new instrument for measuring impurities is a fine jet of air which strikes a glass surface with high velocity, depositing its dust thereon. The velocity of jet affects the operation of the instrument. The adhesion of dust to the glass has suggested applications which indicated (a) that visibility is usually a function of amount of suspended impurity; (b) that suspended dust travels over great distances; records being described of dust from the Continent; (c) that the microscopical examination of such records indicates differences depending upon wind direction.—R. V. Southwell: On the free transverse vibrations of a uniform circular disc clamped at its centre; and on the effects of rotation. An analysis of the influence of rotation upon the normal modes and frequencies of free transverse vibration in a uniform circular disc, complete freedom from constraint being assumed, is extended to cover the effects of constraints which prevent, along a small circle concentric with the free edge, the occurrence either of finite transverse displacement ω, or of finite slope δω/δγ. The constraints are assumed to have no effect upon the centrifugal stress-system. Clamping a non-rotating disc along a small circle produces only slight changes of frequency in modes characterised by two or more nodal diameters, but is important in its effect on the “symmetrical” modes and on modes having one nodal diameter. In the other extreme case, when the flexural rigidity may be neglected, the central constraint has no effect upon the natural frequencies. In the general case, in which both flexural and centrifugal stresses are considered, the gravest frequencies in modes which have nodal diameters may be calculated by the formula previously given; a special investigation is made of the gravest frequency in a symmetrical mode.—A. E. Oxley: Magnetism and atomic structure. II.—The constitution of the hydrogen-palladium system and other similar systems. The susceptibility of palladium black charged with hydrogen is less than that of pure palladium black. From this it is concluded that the occluded hydrogen is neither in the atomic nor molecular state. The results agree with the existence of a chemical compound, probably Pd-H. In the hydrogen molecule, each atom thrusts its electron into the other atom, the bond being represented by a pair of electrons held in common. The palladium atom has 46 electrons, the hydrogen atom I electron, the latter being thrust into the outer shell of the palladium atom. If these 47 electrons take up a configuration like that of the silver atom (atomic number 47), which is diamagnetic, the fall of susceptibility may be accounted for. Paramagnetic manganese fused in hydrogen becomes ferro-magnetic. The occluded hydrogen atoms probably thrust their electrons into the outer shells of the manganese atoms, producing in them electron configurations analogous to that of the iron atom.—T. Carleman and G. H. Hardy: Fourier's series and analytic functions. If f(λ) is integrable in the interval (0, 27π), and the associated function ϕ(u) = ½{f(a+u)+f(a-u)}, where o<a <2π is harmonic and ounded in a certain neighbourhood of u= o, then the necessary and sufficient condition, for the convergence of the Fourier series of f(λ), at λ = a, is that phiv;(u) should tend to a limit when u tends to zero through positive values.—A. McAulay: Multenions and differential invariants. Pts. II. and III. The quadratic form is introduced: all multenion formulae may be put into invariant form. Tests, both by finite and by infinitesimal transformation, are given, for ascertaining whether invariance of each one of six types subsists for any given function. Multenion methods are compared with those of the Theory of Tensors and details are furnished for translating from one mode of presentation to the other. Pt. III. is a general survey of the applications of a Riemann manifold to relativity. In relation to matter and gravitation no new principle is introduced but the electro-magnetic field is treated in a novel manner. The scalar and vector potentials are wholly ignored. The application to matter in bulk is kept in mind, and it is considered imperatively necessary to adapt relativity methods to a sufficiently general set of relations as at least to leave Maxwells explanation of crystalline reflection, refraction, and transmission of light intact.
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Societies and Academies. Nature 109, 289–291 (1922). https://doi.org/10.1038/109289b0
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DOI: https://doi.org/10.1038/109289b0