Abstract
LONDON. Physical Society, June 25.—Dr. A. Russell, vice-president, in the chair.—Sir J. J. Thomson: Conduction of electricity through metals. The discovery by Kamerlingh Onnes, that at the temperature of liquid helium some metals can exist in a state in which their specific resistance is less than one hundred thousand millionth part of that at 0° C, appears to necessitate the abandonment of the ordinary theory of metallic conduction, as the experimental conditions prohibit the explanation of the phenomenon by an abnormal increase, either in the number or mean free path of the free electrons. The effects observed by Kamerlingh Onnes may, however, be accounted for by a theory of metallic conduction previously given by the author in “The Corpuscular Theory of Matter.” On this theory the atoms of some substances contain electrical doublets—i.e. pairs of equal and opposite electrical charges at a small distance apart. The effect of an applied E.M.F. is to alter the heterogeneous distribution of the axes of these doublets by bringing them into partial alignment with the field. The function of the applied field is to produce the alignment of the doublets; the actual transference of electricity is effected by the large interatomic forces brought into being by the polarisation of the doublets. Thus, if the polarisation remains on withdrawing the applied E.M.F. the current will also remain.-Lieut.-Col. G. O. Squler: An unbroken alternating current for cable telegraphy.(1) The paper proposes a new angle of view in the method of transmission of signals in the submarine telegraph cable, and describes some apparatus for operating on the general principles involved.(2) An ocean cable is considered as a power line, and starting with the standard form of circuit which would be used in case it were required to operate an electric motor through an ocean cable, experiments are described to determine the minimum possible variations required in such a circuit to permit the alternating current received to be interpreted in dots, dashes, and spaces of the present alphabet. The uninterrupted alternating current used in transmission is operated on synchronously by the ordinary transmitting tape, so as to alter “the impedance of the transmitting circuit at the instants when the current is naturally zero. Dots, dashes, and spaces are each sent by semi-waves of either sign, but of different amplitudes. The alternating current received may be read directly from the record made by a siphon recorder, or this current may be employed to operate a siphon Morse printer, by means of an adaptation of Muirhead's gold-wire relay, or a Heurt-ley magnifier and a local wire relay.(3) The voltage stress along an Atlantic cable when an alternator is employed is shown, and the transmitting impedance of such a cable is computed as the frequency varies.(4) A special form of cable dynamo to operate at frequencies from 4 to 10 was used in the experiments described.(5) The fundamental principle is developed 1 of never metallically “breaking” the transmitter circuit, which permits of greater accuracy in balancing the duplex bridge.
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Societies and Academies . Nature 95, 551–554 (1915). https://doi.org/10.1038/095551b0
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DOI: https://doi.org/10.1038/095551b0