The transmitter in Fig. 1 consists of a conical tube, a, closed at the smaller end by a collodion membrane, o, on the center of which rests the end of a very light bent lever, c d, supported at e, and thrown

forward into contact with the spring g by the delicate spring n. The spring g is adjustable by the screw h. The electric connections will be easily traced. In the description, g is explicitly described as a spring; and the essential feature to be observed in this type is the current