Page:United States patent 723188.pdf/4

 brations being emitted simultaneously or in rapid succession, as may be desired, at each closure of the circuit. The two receiving circuits at the distant station, each tuned to respond to the vibrations produced by one of the elements of the transmitter, affect the sensitive devices a$1$ and a$2$ and cause the relays R$1$ and R$2$ to be operated and contacts c$1$ and c$2$ to be closed, thus actuating the receiver or relay R$3$, which in turn establishes a contact c$3$ and brings into action a device a by means of a battery d$4$, 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 R$3$ will fail to respond. In this way a communication may be carried on with greatly-increased safety against interference and privacy of the messages may be secured. The receiving-station shown in is supposed to be one requiring no return message; but if the use of the system is such that this is necessary then the two stations will be similarly equipped, and any well known means, which it is not thought necessary to illustrate here, may 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 R$3$, may be made dependent instead of upon two upon more than two such transmitting systems or circuits, and thus any desired degree of exclusiveness or privacy and safety against extraneous disturbances may be attained. The apparatus as illustrated in Figs. and permits, however, special results to be secured by the adjustment of the order of succession of the discharges of the primary circuits P$1$ and P$2$ or of the time intervals between such discharges. To illustrate: The action of the relays R$1$ R$2$ may be regulated either by adjusting the weights of the levers l$1$ l$2$, or the strength of the batteries b$1$ b$2$, or the resistances r$1$ r$2$, or in other well-known ways, so that when a certain order of succession or time interval between the discharges of the primary circuits P$1$ and P$2$ exists at the sending-station the levers l$1$ and l$2$ will close the contacts c$1$ and c$2$ at the same instant, and thus operate the relay R$3$, but will fail to produce this result when the order of succession of or the time interval between the discharges in the primary circuits is another one. By these or similar means additional safety against disturbances from other sources may be attained and, on the other hand, the possibility afforded of effecting the operation of signaling by varying the order of succession of the discharges of the two circuits. Instead of closing and opening the circuit of the source S$1$, as before indicated, for the purpose of sending distinct signals it may be convenient to merely alter the period of either of the transmitting-circuits arbitrarily, as by varying the inductance of the primaries.

Obviously there is no necessity for using transmitters with two or more distinct elements or circuits, as S$1$ and S$2$, since a succession of waves or impulses of different characteristics may be produced by an instrument having but one such circuit. A few of the many ways which will readily suggest themselves to the expert who applies my invention are illustrated in Figs. ,, and. In a transmitting system e s$3$ d$3$ is partly shunted by a rotating wheel or disk D$3$, which may be similar to that illustrated in  and which cuts out periodically a portion of the coil or conductors s$3$, or, if desired, bridges it by an adjustable condenser C$3$, thus altering the vibration of the system e s$3$ d$3$ at suitable intervals and causing two distinct kinds or classes of impulses to be emitted in rapid succession by the sender. In a similar result is produced in the system e s$4$ d$4$ by periodically short-circuiting, through an induction-coil Land a rotating disk D$4$ with insulating and conducting segments, a circuit p$4$ in inductive relation to said system. Again, in three distinct vibrations are caused to be emitted by a system e s$5$ d$5$, this result being produced by inserting periodically a number of turns of an induction-coil L$4$ in series with the oscillating system by means of a rotating disk B$5$ with two projections p$5$ p$5$ and three rods or brushes in, placed at an angle of one hundred and twenty degrees relatively to each other. The three transmitting systems or circuits thus produced may be energized in the same manner as those of or in any other convenient way. Corresponding to each of these cases the receiving-station may be provided with two or three circuits in an analogous manner to that illustrated in, it being understood, of course, that the different vibrations or disturbances emitted by the sender follow in such rapid succession upon each other that they are practically simultaneous so far as the operation of such relays as R$1$ and R$2$ is concerned. Evidently, however, it is not necessary to employ two or more receiving-circuits, but a single circuit may be used also at the receiving-station constructed and arranged like the transmitting-circuits or systems illustrated in Figs. ,, and , in which case the corresponding disks, as D$3$ D$4$ D$5$, at the sending will be driven in synchonismsynchronism [sic] with those at the receiving stations as far as may be necessary to secure the desired result; but whatever the nature of the specific devices employed it will be seen that the fundamental idea in my invention is the operation of a receiver by the conjoint or resultant effect of two or more circuits each tuned to respond exclusively to waves, impulses, or vibrations of a certain kind or class produced either simultaneously or successively by a suitable transmitter.

It will be seen from a consideration of the nature of the method hereinbefore described that the invention is applicable not only in the special manner described, in which the transmission of the impulses is effected through natural media, but for the transmis