Showing papers in "Philosophical Transactions of the Royal Society A in 1939"
TL;DR: The possibility of obtaining some knowledge of the distribution of electrical conductivity within the earth, from the observed variations of the earth's magnetic field, was first considered by Schuster (1889), in developing his theory of the daily magnetic variations as mentioned in this paper.
Abstract: The possibility of obtaining some knowledge of the distribution of electrical conductivity within the earth, from the observed variations of the earth’s magnetic field, was first considered by Schuster (1889), in developing his theory of the daily magnetic variations He separated these variations into parts of external and internal origin, and then applied the theory of electromagnetic induction in a uniform sphere, due to Lamb (1883), to show that the “internal” part could be attributed to electric currents induced in the earth by the “external” part Chapman (1919) made a more complete analysis of the diurnal variation field, and showed that it was consistent with the earth having a core of conductivity k = 36 x l 0-13 emu, surrounded by a non-conducting shell of about 250 km thickness Chapman and Whitehead (1922) found, however, that the relatively highly conducting oceans probably have an appreciable effect on the internal field, and thus introduce some uncertainty in the estimate of k
290 citations
TL;DR: In this article, the one-electron radial wave functions were calculated by the method of the selfconsistent field without exchange, but exchange terms were included in the calculation of the energy from these radial wave function.
Abstract: The calculation of approximate wave functions for the normal configurations of the ions O +++, O ++, O +, and neutral O, and the calculation of energy values from the wave functions, was carried out some years ago by Hartree and Black (1933)- In this work, the one-electron radial wave functions were calculated by the method of the selfconsistent field without exchange, but exchange terms were included in the calculation of the energy from these radial wave functions. In the energy calculations, the same radial wave functions were taken for each of the spectral terms arising from a single configuration; * consequently the ratios between the calculated intermultiplet separations were exactly those given by Slater’s (1929) theory of complex spectra, f The ratios between the observed intermultiplet separations, however, depart considerably from these theoretical values (for example, we have for 0 ++ (1D - 1S) / (3P - 1D), calc. 3 : 2, obs. 1.04 :1), although the energies of the individual terms, and particularly the intermultiplet separation between the lower terms, show quite a good agreement with the observed values.
167 citations
TL;DR: The first accurate laboratory determination was made about the same time by Biot and Arago (1806), who measured the deviation of white light passing through air enclosed in a hollow glass prism.
Abstract: (a) Note on previously recorded values of the refractive index of air. For many centuries astronomers have recognized the effect that the refraction of the earth’s atmosphere has upon observations of the positions of celestial bodies. From the time of Tycho Brahe, when astronomical technique became sufficiently refined for the purpose, attempts have been made to apply corrections for the deviation of light in its passage through the earth’s atmosphere, and ultimately, in 1805, Delambre (1806) determined, by comparing a large number of astronomical observations, a value of the refractive index of atmospheric air for white light. The first accurate laboratory determination was made about the same time by Biot and Arago (1806), who measured the deviation of white light passing through air enclosed in a hollow glass prism. In 1857 Jamin (1857 b) made his original application of the methods of interferometry to the measurement of the refractive index of a gas. The increased accuracy obtainable by the use of the principle of the Jamin refractometer enabled Ketteler (1865) to determine the refractive indices of air for the red, yellow and green lines in the visible spectra of lithium, sodium and thallium respectively, and thus to make some of the earliest measurements of the dispersion of air.
159 citations
TL;DR: In this paper, the authors consider the problem of determining how the presence of holes in a uniform plate under given applied forces effects the distribution of the stresses in the plate (see Coker and Filon 1931, chap. iv).
Abstract: A number of investigations, both experimental and theoretical, have been made to determine how the presence of holes in a uniform plate under given applied forces effects the distribution of the stresses in the plate (see Coker and Filon 1931, chap. iv). When there is a single hole in a plate which may be considered infinite, the problem is elementary ; but a hole near to a straight boundary or to a similar hole greatly influences the maximum stress and complicates the mathematical solution. No general method of solution has been given and we now extend methods, previously used by the present writers in particular cases, to a group of problems in which the boundaries possess a certain invariance. The boundaries we shall consider are a set of equal circles together with in some cases a pair of parallel straight lines. With each of the circles is associated a rectangular co-ordinate system, and it is essential to the method that the boundaries, boundary conditions and infinity conditions should remain invariant under a trans-formation in which each co-ordinate system and corresponding circle transforms into another system and circle of the set.
36 citations
TL;DR: In this paper, the authors gave an account of magnetic studies on single crystals of several paramagnetic salts of the rare earth and the iron groups, and a discussion of the results on the basis of the recent theoretical work of Van Vleck (1932 a, b ), and Penney and Schlapp (19 1932), on the influence of the strong local electric fields acting on the paramagnetic ions in the crystals on their magnetic behaviour.
Abstract: In some of the earlier papers in this series (Part II, 1933; Part IV, 1936; Part V, 1938) we gave an account of magnetic studies on single crystals of several paramagnetic salts of the rare earth and the iron groups, and a discussion of the results on the basis of the recent theoretical work of Van Vleck (1932 a, b ), and Penney and Schlapp (1932), on the influence of the strong local electric fields acting on the paramagnetic ions in the crystals on their magnetic behaviour. Paramagnetic studies on single crystals are of interest because of the variety of information one can obtain from them under favourable conditions—on such widely different topics as the magnitude and the asymmetry of the electric field acting on the paramagnetic ion in the crystal; the geometry of distribution of the negatively charged atoms immediately surrounding the paramagnetic ion, and hence the co-ordination number of the ion; the strength of coupling between the orbital and the spin angular momenta of the electrons in the incomplete shell of the ion; and in those crystals in which the paramagnetic ions are all in the S-state, the magnitude of the Stark separation of the S-levels, which plays an important part in determining the thermal properties of the crystal at very low temperatures ( = 0T °K ); etc. Several examples were given, in the papers referred to, to illustrate these various aspects of the magnetic studies on paramagnetic crystals.
24 citations
TL;DR: The first study of meteoric iron by X-ray methods was undertaken at the instigation of Professor S. W. Smith, F.R.S. and J. J. Young as mentioned in this paper.
Abstract: The first study of meteoric iron by X-ray methods was undertaken at the instigation of Professor S. W. J. Smith, F.R.S. some years ago. This research (Young 1926) resulted not only in the determination of the crystal structures of two of the main constituents, kamacite and taenite, but also in the important discovery of the nature of the mutual orientations of these constituents when the meteorite exhibits a Widmanstatten structure. As is well known, the Widmanstatten figures in meteorites arise from the arrangement of kamacite lamellae on the planes of an octahedron, and for that reason a meteorite exhibiting these figures is generally referred to as an octahedrite. The kamacite lamellae, therefore, fix the {I I I}-planes of a hypothetical cubic lattice whose principal axes, XYZ , will be referred to as “ the axes of the octahedrite”.
8 citations
1 citations