Abstract
Wiedemann's Annalen der Physik und Chemie, No. 10.—On air vibrations, by A. Raps. The changes of density at the nodes of open and closed organ pipes were recorded by allowing a beam of strong white light to fall upon the mirror of a Jamin interference refractor. One of the reflected beams was sent through a pipe at the node, the other through a box containing undisturbed air. After reunion by the second mirror, these two beams gave rise to interference fringes, which were displaced during the changes of density accompanying the sound of the pipe. A section across these fringes, consisting of bright and dark points, was received upon a revolving drum carrying sensitive paper, and the oscillation of the points gave rise to a series of curves representing the sound vibrations with very fair accuracy. A series of eighty-eight photographs are reproduced, which give valuable hints concerning the structure of the various notes, and also some vowels and consonants produced in the open air.—Luminous phenomena in electrode-less vacuum tubes under the influence of rapidly alternating electric fields, by H. Ebert and E. Wiedemann. This paper, a sequel to the general investigation published in No. 9, deals with the details of the phenomena observed between the condenser plates of a Lecher wire system in the case of spheres, cylinders of various lengths, conaxial double cylinders, and glass parallelepipeds with plane ends.—Heat of dissociation in electro-chemical theory, by H. Ebert. Calculations based upon heat of dissociation and electrolytic work show that the forces of chemical affinity are chiefly of an electric nature, that the forces due to “valency-charges” are the most powerful of any atomic forces, and that any additional chemical forces are, in comparison, infinitesimal.—Equipotential lines and magnetic lines of force, by E. von Lommel. Some further photographic tracings of these lines are given, and their bearing upon the Hall effect is discussed.—Objective representation of interference phenomena in spectrum colours, by the same author. Simple arrangements are described for exhibiting Newton's rings, gypsum fringes, convergent polarised light phenomena, and fringes produced by the rotation of the plane of polarisation in quartz prisms, upon a screen. For Newton's rings the light from the heliostat is reflected by a colour plate, and falls upon a lens which produces an image of the sun at its focus. By placing a slit at this focus and a prism between slit and lens, the rings in all the spectrum colours may be thrown upon the screen by shifting the slit.—Papers by Kayser and Runge, P. Czermak, and R. J. Holland have already been mentioned.
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Scientific Serials. Nature 49, 46 (1893). https://doi.org/10.1038/049046a0
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DOI: https://doi.org/10.1038/049046a0