Nikola Tesla U.S. Patent 725,605 - System of Signaling Patent Wrapper Page 26

640 + two stations may be equipped similarly, and any well-known means, which it is not thought ne cessary to illustrate here, may be resorted to for enabling the apparatus at each station to be used in turn as transmitter and receiver. The apIn like manner the operation of a receiver, as R³, ray 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 against 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 and p2. To illustrate, the relays R¹ R²may be regulated either by adjusting the weights of the levers 112, or the strength of the batteries ²2, or the resistances 2, or otherwise, so that, when a certain order of suc cession or difference of phase between the discharges of the primary d rcuits P¹ and ² exists at the sending station, the levers 1 and 12 will close the contacts c²² at the same instant, and thus operate the relay R³, but: will fail to produce this result when the order of succession is a different one. This insures a greater safety against disturbances from other sources and makes it possible, on the other hand, to effect the operation of signalling by merely varying the order of sion of the impulses. Instead of closing and opening the circuit of the source S, as before stated, for the purpose of sendirg distinct signals, it will be sufficient to merely alter the pericd of either of the transmitting circuits arbitrarily in any of the well-known ways, as by varying the -8succes