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Societies and Academies

Nature volume 96, pages 697698 (17 February 1916) | Download Citation



LONDON. Royal Society, February 10.-Sir J. J. Thomson, president, in the chair.-Lord Rayleigh: The theory of the Helmholtz resonator. The ideal form of a Helm-holtz resonator is a cavernous space enclosed in a thin immovable wall, but communicating with the external atmosphere by means of a small perforation. An approximate theory is due to Helmholtz, who arrived at definite results for apertures the outline of which is circular or elliptic. In the present paper the approximation is carried further for the special case where the wall is spherical, with the aid of the appropriate Legendre's functions.-Sir Norman Lockyer and H. E. Goodson; The oxyhydrogen flame spectrum of iron. A spectrogram of the light oemitted when metallic iron burns in the oxyhydrogen flame, notably rich in lines due to the metal, has been studied. Sixty-four lines of iron have been identified in the region AA 3856-52 -56i5'-88. Fifteen of these lines do not appear to have been hitherto recorded in the iron-flame spectrum, and a number of these latter possess special interest. On the basis of a comparison of the flame spectrogram with a spectrum of the iron arc of approximately similar exposure, it has been possible to separate the flame lines according to the observed variations of intensity into two well-marked groups, whilst a residuum forms an intermediate group. All the flame lines have accordingly been placed in one or other of the following three groups:—

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