Nikola Tesla U.S. Patent 723,188 - Method of Signaling Patent Wrapper Page 23

580 Jer B a' Each of the receiving coils and s² is shinted by a local circuit containing, respectively, sensitive devices , batteries h 22, adjustable resistances rl 2² and sensitive relays R1 R2, all joined in series, as shown. The precise connections and arrangements of the various instruments are largely immaterial, and may be varied in many ways. The sensitive devices al a2 ray be any of the well known devices of this kind, as for example, two filcting terminals sepa rated by minute air gap or thin sil of dielectric, which is strained or weakened by a battery or other means to the point of breaking down, and gives way to the slightest disturbing influence. Its return to the normal sensitive state may be secured by momentarily interrupting the bat tery circuit after each operation, or otherwise. The relays R1 R2 have armatures 112, which are connected by a wire w, and when attracted, establish electrical contacts at and , thus closing a circuit containing a battery b3 an adjustable resistancer3 and a relay R³, From the above description it will be readily seen that the relay R3 will be operatedonly when both contacts and are closed. The apparatus at the sending station may be controlled in any suitab le manner, as for instance, by momentarily closing the circuit of the source S. Two different electric vibrations will be cmitted simultaneously or in rapid succession, as may be desired, at each closure of the circuit. The two receiving circuits at the distant station cach tuned to respond to the vibrations produced by one of the elements of the transmitter affect the sensitive devices al and a2 and cause the relays Rl and R2 to be operated and contacts and to be closed, thus actuating the receiver -6