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Page:Popular Science Monthly Volume 49.djvu/117

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105
RECENT WORK ON X RAYS.

"1. Black paper (sixteen leaves interposed). The collapse of the gold leaves is immediate and complete in a few seconds; they do not rise again. 2. Plate of brass (two tenths of a millimetre in thickness). No change in the divergence of the gold leaves. 3. Plate of aluminum (one tenth of a millimetre). Immediate fall, complete in a few seconds; same result with plates of aluminum up to one millimetre, and even upward, and the Crookes tube being removed to the distance of thirty centimetres. The substances easily traversed are silver in beaten leaves, leaves of paper steeped in metallic solutions, vulcanized fiber, gelatin, celluloid, ebonite, etc. The substances not traversed, at least in the thicknesses employed, are brass, zinc, glass, and unglazed porcelain (three millimetres). Similar results have since been announced from several other investigators."

A paper by G. Jaumann, under the title of Longitudinal Light, is described in Nature: "It is based upon the law of electric discharge enunciated by Jaumann in 1888, according to which electric rays impinging at right angles upon a cathode surface favor the dissipation of the charge upon it. Hence, the writer argues, light vibrations must have a component in the direction of propagation; they must, in fact, contain longitudinal as well as transverse waves. It then becomes a question of how Maxwell's electro-magnetic equations, which do not admit of any but purely transverse vibrations, can be made to agree with these conclusions. Jaumann gives a simple answer. Let it be admitted that the specific induction capacity of a medium and its magnetic permeability are affected by the oscillations themselves. These 'constants' will then be variable, and when introduced as such into the equations longitudinal vibrations are at once seen to be possible. Each pencil of light will then be vibrating transversely along its center line, and toward the outer edge the vibrations will become more and more longitudinal. The author claims that this theory affords a natural and simple explanation of a large number of discharge phenomena."

Prof. Oliver Lodge, of University College, Liverpool, is reported as having said that he felt inclined to adopt the view that the new rays were longitudinal waves in the ether; and that if this were so the discovery would open up a department of physics as large as light, sound, or electricity. Later, in a letter to Nature, discussing the theory of the anodal origin of the X rays, he says: "The term 'anode rays' for the rays discovered with so much éclat by Prof. Röntgen, whether they be the same as those previously discovered by Dr. Lenard or not, is suggested by the remarks of Mr. A. W. Porter at a recent meeting of the Royal Society. They certainly do not start from the cathode, but from some opposed surface—a surface which may be an actual anode.