Abstract
LONDON. Royal Society, March 14.-Sir J. J. Thomson, president, in the chair.-A. W. Conway: An expansion of the point-potential. The general solution of the equation C2v2^=^ which is infinite at: the origin, is of the form f(Ct±r)/r. This is infinite to the first degree. Referred to a different origin, a known expansion gives the series SYwUn, where Y? is a spherical harmonic and Un is a certain function of t and of the distance to the new origin. This is a generalisation of the Legendre expansion of the inverse distance. In the paper the potential scale or vector of a moving point-charge is expanded in a similar series of spherical harmonics, the only restriction on the motions of the point-charge and of the origin being that the speed of the former must be less than that of light.-E. G. Bilham: The lunar and solar diurnal variations of water-level in a well at Kew Observatory, Richmond. The mean solar and lunar diurnal inequalities have been computed from two-hourly measurements of the Kew Observatory water-level records over a period of two years. Results are given for each month, for the year, and for groups of months, representing high, intermediate, and low levels. Both the lunar and solar diurnal ranges are found to be largely dependent on the level of the water, high levels being associated with large diurnal range. In a paper recently communicated to the society it was shown that a similar relation exists between the mean level and the sensitiveness to the effects of barometric pressure. There are well-marked lunar and solar semi-diurnal oscillations throughout the year, the amplitude varying with the level in a manner similar to the diurnal range. In both cases the phase also varies with the level, the effect being most pronounced in the lunar results. The times of occurrence of the maxima become later as the water-level falls. In comparison with the total oscillations in the neighbouring River Thames, the well shows larger solar diurnal movements than were to be anticipated from the magnitude of the lunar oscillations. If, however, allowance is made for the effects of the solar diurnal variation of barometric pressure, the residual effects attributed to the solar tides are of the expected order of magnitude.
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Societies and Academies . Nature 101, 78–80 (1918). https://doi.org/10.1038/101078a0
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DOI: https://doi.org/10.1038/101078a0