Proceedings of the Physical Society, Volume 13

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Institute of Physics and the Physical Society., 1895 - Physics

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Page 303 - As a unit of resistance, the international ohm, which is based upon the ohm equal to 10" units of resistance of the CGS system of electromagnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of the length of 106.3 centimetres.
Page 303 - Ampere, which is one-tenth of the unit of current of the CGS system of electromagnetic units and which is represented sufficiently well for practical use by the unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with a certain specification, deposits silver at the rate of 0.001118 of a gramme per second.
Page 121 - It consists essentially of a strip of very thin platinum, about 10 centim. long, 1 centim. broad, and ^ millim. thick. The plane of the strip is vertical. It can be heated by an electric current, and its linear expansion is indicated by an optical method, by which an alteration in temperature of 1° can easily be noticed. The method of calibration is described in Joly's paper t, and in that already mentioned, so that it is unnecessary to do more than briefly refer to it here. Minute fragments of...
Page 42 - It may be here noted that such objects may be made by drawing rather thick figures in ink upon a card about 1 foot square and reducing by photography to 1 inch square : the negatives so produced give the desired transparent lines on a dark ground : it will be understood that a circle means a circular line of light in distinction to a circular area. The play of light-waves in a shadow gives rise to infinite paradox. The most notorious is Arago's bright spot at the centre of the shadow of a circular...
Page 591 - Sharp read a piper entitled a new metho:! in harmonic analysis. The author, in this paper, applies the principle of the form of harmonic analysis for giving direct readings of the amplitude and epoch of the various constituent harmonic terms, previously described by him, to the performance of harmonic analysis without the use of an instrument. The kinematic principle is as follows : Let the curve to be analysed be drawn with a scale of abscissa such that the period is 2r.
Page 303 - ... 10. That an unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with the specification attached to this Report, deposits silver at the rate of 0-001118 of a gramme per second, may be taken as a current of one ampere.
Page 276 - I~ 77) i an<l the phenomena of crystalline media could be included by assuming a vector-coefficient instead of the scalar a. The conclusion, then, is that in this limited range an elasticsolid theory of a very rare aether is not so much at fault as would at first sight appear. A theory based on difference of rigidity without difference of inertia, after...
Page 487 - La seconde expérience consiste dans l'influence qu'éprouvé une lame de cuivre pliée en cercle de la part d'une ceinture de forts courans électriques au milieu desquels elle est suspendue , et qui l'entourent sans la toucher. Cette influence, que M. Ampère avait d'abord crue nulle, a éié,à Genève, constatée par lui-même d'une manière Irès-pre'cise. En présentant à un côté de cette...
Page 280 - ... small inertia, and consequently a small elasticity, to be assigned to the aether, and so prevents it from acting as an appreciable drag or exerting an appreciable force on finite bodies moving through it. But these very properties would incapacitate it for acquiring the very large volume-densities of energy that would have to be associated with it in order to explain electrodynamic phenomena. Any representation which would make the aether consist of molecules of ordinary matter is open to the...
Page 414 - The next experiment was directed to determine the objective reality of Konig's lower beat-tone when the interval was greater than an octave. The 8 and 18 rows of holes being kept open as before, the speed was increased until the lower note was that of 256 vibrations. The upper note was then 576, and Konig's lower beat-tone was of 576 — 2x256 = 64 vibrations. We lay less stress on negative than on positive results ; but we tried for a long time on two occasions to get evidence of the objective character...

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