Nikola Tesla U.S. Patent 723,188 - Method of Signaling Patent Wrapper Page 11

568 cr closing the circuit of the source S, electrical vibrations being sent out simultaneously or in rapid succession, as may be desired, at each closure of the circuit. The two receiving circuits at the distant station, each responding to the vibrations produced by one of the elements of the transmitter, affect the sensitive devices al and a² and cause the relays R and R2 to be operated and contacts and closed, thus actuating the receiver or relay R³, which in turn establishes a contact and brings into action a device a3 by means of a battery included in a local circuit, as shown. But evidently, if through any extraneous disturbance only one of the circuits at the receiving station is affected, the relay R³ will fail to respond. In this way communication may be carried on with much increased safety, and entire privacy of the messages may be secured. The receiving station shown in Fig. 2 is supposed to be one requiring no return message, but if the use of the system is suc th this is necessary, then the two stations will be equipped similarly, and any well-known me ans, which it is not thought necessary to illustrate here, will be resorted to for enabling the apparatus at each station to be used in turn as transmitter and receiver. In like manner the operation of a receiver, as R³, 1 may be made dependent, instead of upon two, upon more than two such transmitting systems or circuits, and in this manner any desired degree of exclusiveness or privacy and safety The apagainst extraneous disturbances may be attained. paratus, as illustrated in Fig. 1, permits, however, specific results to be attained by the adjustment of the phase difference between the discharges of the primary circuits pl L