SOME EXPERIMENTS ON THE ELECTRIC DISCHARGE IN VACUUM TUBES.[1]
By Prof. J.J. THOMSON, M.A., F.R.S.
FIG. 1.—Coil of Glass Tube for Vacuum Discharge Experiments. The primary coils are filled with mercury, the secondary coils form continuous closed circuits.
The phenomena of vacuum discharges were, he said, greatly simplified when their path was wholly gaseous, the complication of the dark space surrounding the negative electrode and the stratifications so commonly observed in ordinary vacuum tubes being absent. To produce discharges in tubes devoid of electrodes was, however, not easy to accomplish, for the only available means of producing an electromotive force in the discharge circuit was by electromagnetic induction. Ordinary methods of producing variable induction were valueless, and recourse was had to the oscillatory discharge of a Leyden jar, which combines the two essentials of a current whose maximum value is enormous, and whose rapidity of alternation is immensely great.
FIG. 2.—Exhausted Bulb Surrounded by Primary Spiral Consisting of a Coiled Glass Tube Containing Mercury.
FIG. 3.—Exhausted Bulb Surrounded by Primary Coils, Inclosed in Bell Jar.