Abstract :
R. C. Mason (Westinghouse Electric and Manufacturing Company, East Pittsburgh, Pa.): Paschen´s law, as the authors have explained and emphasized, applies only for uniform fields. As the engineer often must deal with nonuniform fields, the more general Principle of Similitude, of which Paschen´s law is merely a special case, really should be the guide in gas-discharge work. As applied to gas breakdown, the principle of similitude requires all linear dimensions of the apparatus to be multiplied by the same factor which divides the gas density, in order for the starting voltage of the discharge to be unchanged; it is not enough merely to change the separation of the electrode. Further, with nonuniform fields, breakdown voltage is not a function of pd alone.
