17,706. Fessenden, R. A. Aug. 12. Telephone systems. -R elates to a system of wireless signalling such as is applied for transmitting and receiving words and other audible sounds. Fig. 1 shows one arrangement, in which a microphone 9 is arranged in one circuit 7 of a transformer 3, the other circuit 2 being connected to the aerial conductor 1 and one spark knob 4. The generator is arranged to produce sustained waves, and the spark gap is shunted by a condenser 18 and inductance 19 in tune with the aÙrial radiator 1 and aÙrial collector 10. The receiver consists of a telephone coil 11 in proximity to a magnetic or equivalent diaphragm 12 or a coil. In a modified form, the microphone and transformer are omitted, and a condenser shunt substituted, one plate of the condenser being free and the other fixed. In another modification, a highpotential rapid alternator, preferably such as is described in Specification No. 17,70B, A.D. 1902, is employed as a generator, and is connected to the aerial radiation through a microphone adapted for use with large currents.