Signalling through space without wires : being a description of the work of Hertz & his successors . lmatters. [The Paper and plates are worthy of reproduction in full inthe Philosophical Magazine.] Weil. Ann., 46, p. 281.—On the Behaviour of Alkali MetalCathodes in Geissler Tubes; On Photo-Electric Discharge in aMagnetic Field; and On the Measure of Photo-ElectricCurrents in Potassium Cells by means of a Galvanometer. Eesults :—The resistance of a Geissler tube provided with acathode surface of pure alkali metal is diminished by the lightfrom the sparks of an induction coil; especially when t
Signalling through space without wires : being a description of the work of Hertz & his successors . lmatters. [The Paper and plates are worthy of reproduction in full inthe Philosophical Magazine.] Weil. Ann., 46, p. 281.—On the Behaviour of Alkali MetalCathodes in Geissler Tubes; On Photo-Electric Discharge in aMagnetic Field; and On the Measure of Photo-ElectricCurrents in Potassium Cells by means of a Galvanometer. Eesults :—The resistance of a Geissler tube provided with acathode surface of pure alkali metal is diminished by the lightfrom the sparks of an induction coil; especially when thepressure is *1 to -01 mm. of mercury. The resistance whichrarefied gas opposes to an electric current in a magnetic fieldis greatest in the direction normal to the magnetic changes of resistance effected by any kind of light in avacuum tube with alkali metal cathode can be measuredgalvanometrically. (A Daniell cell gives 100 divisions on aEosenthal galvanometer when coupled up through such anilluminated tube, each division meaning about 1010 ampere.) PHOTO-ELECTRIC PHENOMENA. 125. Fig. of Fig. 64. —A vacuum tube of rarefied hydrogen containingalkali metal as cathode, say the liquid K—Na alloy, or solid K or Na. Aspark gap at S serves as alternative path, and a stream of sparks can occurto the plate P in the dark. But when light falls on the surface A thisstream of sparks can cease, showing that the resistance of the vacuum tubeis diminished.
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