A new method for initiating the cathode or an arc

AFTER presenting various theories of the cathode of an electric arc and describing numerous methods for initiating an arc cathode, a new method of starting the arc cathode is described. It is of the separating contact type, but to a considerable degree is free from the inertia difficulty of ordinary separating contacts. One form of this starter consists of a small section pointed tungsten rod placed in a mercury arc tube so that it dipped slightly to a depth of about one mm below the mercury surface. On sending sufficient current through the rod, the cathode of an arc was promptly started at the rod and mercury junction, and this starting could be regularly repeated 60 times per sec.