US1043314A - Telephone system. - Google Patents

Description

0. L. GooDRUM. TELEPHONE SYSTEM. APPLICATION FILED MAE. 15, 1902.

1,043,314. Patented Nov. 5, 1912.

M www COLUMBIA PLANouRAPM co.,w^sH|NG1-0N. D. c.

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CHARLES L. GOODRUIVI, OF ATLANTC CITY, NEW JERSEY, ASSIGNOR, BY MESNE AS; VSI(rNlViEN'JIS, TO STROIVIBERG-CARLSON TELEPHONE MANFACTURING COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.V

TELEPHONE SYSTEM;

Specification of Letters Patent.

Patented Nov. 5,1912?.

Application led March 15, 1902. Serial No. 98,304.

VTo all whom 'it may concern:

Be it known that I, CHARLES L. GrooDnUM, a citizen of the United States, residing at Atlantic City, county of Atlantic, and State of New Jersey, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

My invention relates to telephone systems of the complete metallic circuit and central energy type. in systems of this character it is usual to provide complete metallic circuits between sub-stations and a central exchange. It is also the practice to operate the various signa-ls, as for example, the line and supervisory signals at a central exchange, and also the bells at the subscribers stations, by current from suitable sources of supply located at the central station. At the central exchange the switch-board is provided with what are commonly known as jacks, each jack being co-nnected with a subscribers line. The central operator is usually provided with a connecting` medium, preferably in the form of a cord having two or more strands provided at each end with a plug. These plugs are adapted for insertion inthe jacks, so as to establish co-nnection between the lines of any two subscribers. Ordinarily the operator is provided with a generator for ringing the bells at the sub-stations. The line and supervisory signals are operated by current supplied from the common battery at the central station. When the subscriber sends in a call the line signal is operated, so as to attract the attention of the central operator, and the latter, after learning the number of the subscriber desired, makes the connection with the plugs and 'cord circuit. When the subscribers at the substation hang up the receivers the supervisory signals are brought into operation and the central operator is, in this way, advised that the subscribers are through talking. The common battery at the central exchange is so arranged as to supply current over the lines to the microphone transmitters at the sub-stations. In this way, as stated, the current, both for talking and calling purposes, is supplied entirely from one or more batteries or generators located atthe central exchange. rlhe line and supervisory signals are usually in the form of small incandescent lamps, arranged in position to be easily observed by the central operator. The circuits for these lamps are automatically closed by relays, which are energized or deenergized, as the arrangement may require, by the closing or opening of the line circuits.

Generally stated, it is the objectof my invention to provide a simple and highly efficient telephone system of the foregoing character.

A special object is to provide a simplified and improved arrangement of circuits and apparatus for operating the line signals.

It is also an object to provide certain details and features of improvement tending to increase the general efficiency, and to render a system of this character more serviceable and satisfactory in use.

To the foregoing and other useful ends my invention consists in matters hereinafter set forth and claimed.

The accompanying drawing is a diagram illustrating a telephone system embodying the principles of my invention.

In this diagram it will be observed that only two subst-ations together with a cord circuit and line connections are shown, and

`it will be understood that only such instruments and apparatus are illustrated as are necessary to a full understanding of the invention.

As far as the construction of the system is concerned, it will be readily understood that the system comprises any suitable number of sub-stations equipped with subscribers apparatus of any suitable or approved character. For example, the subscribers apparatus may be substantially of the character shown at sub-stations A and B, these substations being connected with the exchange or central station in any suitable manner.

`Preferably, however, complete metallic line connection is employed between the substations and the switch-board apparatus at the exchange or central station. Also, it will be readily understood that the battery shown at the central station or exchange is adapted to furnish current for both talking and signaling purposes that is to say, this battery furnishes the current for both operating the line and supervisory signaling apparatus, and for charging the transmitters at the sub-stations. As illustrated, the subscribers lines terminate in spring jacks of a character hereinafter mo-re particularly described, these spring jacks being mounted in any suitable manner on the switchboard at the central station. Also, as shown, the switch-board apparatusincludes any suitable number of cords or operators cord circuits, each cord being provided with plugs adapted for insertion in the said jacks; and it will also be seen that the line relays and the line signals are associated with the lines, while the supervisory signals and supervisory relays are associated with the cord circuits. The different circuit arrangements, and the functions of the different devices, will, however, be more clearly understood by considering the various connections and operations which take place in connecting up one subscriber with another. Therefore as thus illustrated, and assuming that the subscriber at sub-station A desires connection with a subscriber at substation B, the operation and circuit connections which take place are as follows: `When the receiver is removed from the hookswitch at substation A, a circuit is closed from battery 1 through conductor 2, through the switch-spring 3 and contact point 4, thence through conductor 5, through the transmitter 6, through the receiver 7, thence through the contact point 8, and the hookswitch 9, through the line conductor 10, through the coil 11 of the line relay R, thence through contact point 12 and switch-spring 13, and through conductor 14 to said battery. The current flowing through this closed line circuit energizes the relay R, causing the latter to attract its armature. The said armature when attracted closes a short local circuit from battery 1 through conductors 2 and 15 through the armature 16, the contact point 17, thence through conductor 18, through the line lamp signal 19, conductors 2O and 21, and through conductor 14 to said battery. This lights the line lamp signal 19, thereby advising the central operator that the subscriber at substation A has sent in a call. The central operator then inserts the answering plug P of the cord circuit in the jack J, so as to establish connection between the calling subscribers line and the operators talking set in the cord circuit. The insertion of the answering plug in the jack in this manner completes a short local circuit from the battery 1 through the conductors 14 and 21, through the coil 22 of the cut-out relay R1, through conduct-or 23, through the tip spring 24 of the jack, thence through the tip contact 25 of the plug, through the cord strand 26, through the coil 27 of the supervisory relay R2, thence through conductor 28 and the winding 29 of the repeating coil, and thence through conductors 30 and 2 to said battery. This energizes both the cut-out relay R1 and the supervisory relay R2. The relay R1 attracts its armature r, thereby opening the two switch-points controlled by the switchsprings 3 and 13, and in this way severing the direct connection between the battery and the line. This, it will be observed, serves to denergize the relay R, and the latter in releasing its armature opens the switchpoint in the circuit of the lamp 19. 1n this way the insertion of the answering plug op crates to automatically extinguish or restore the line signal. It will also be seen that when the answering plug is thus inserted, a line circuit is closed fromv the battery 1 through the conductor 31, through the winding 32 of the other repeating coil, through the conductor 33, thence through the coil 34 of the supervisory relay R3, through the cord strand 35, the sleeve 36 of the plug, thence through the thimble or ring 37 of the jack, through the line conductor 5, through the transmitter 6 and receiver 7, through the contact point 8 and hook-switch 9, thence through the line conductor l0, through the contact spring 38 of the jack, through the tip contact 25 of the plug, through the cord strand 26, through the relay R2, through the conductor 28 and the repeating coil winding 29, thence through the conductors 30 and 2 to said battery. The energization of the relay R3 by the closing of the line circuit closes a normally open shunt connection around the relay R2, consisting of the conductor 39, the armature 40, contact .point 41 and the conductor 42. This denergizes the relay R2, and prevents the latter from attracting its armature and thereby closing the circuit of the supervisory lamp. In this way, when the answering plug is inserted, the relay R3 is made a part of the line circuit and the relay R2 is made a part of such line circuit and also a part of a local circuit. At this juncture, it will be understood that the operator communicates with the calling subscriber in any suitable manner as, for example, by pressing an ordinary listening key, so as to bridge the operators talking set across the cord circuit, in the usual manner. After learning the number of the substation desired, the operator then inserts the calling plug P1 in the jack J1. The operator also then presses the ringing key,rso as to bridge the generator across the cord circuit, and then by operating the generator ringing current is projected onto the line of the called for subscriber, for the purpose of ringing the bell at the latters sub-station. At this juncture, it will be seen that the line has been put into proper condition to permit the operation of the generator by the severing of the connect-ion between the battery and the line, due to the energization of the cut-off relay R4.

lVhen the calling plug P1 is inserted a local circuit is completed from the battery thii'ough the conductors 2 and 30, through the winding 43 of the repeating coil, through conductor 44, through coil 45 of the supervisory relay R5, through the conductor 4G., through the spring 47 of the listening key, through the cord strand 48, through the plug tip 49, through the tip spring 50 of the jack, thence through the conductor 51, through the coil 52 'of the cut-out relay R4, thence through the conductors 53 and 14 to said battery. This energizes the supervisory relay R5 and, as stated, also energizes the cut-out relay R4. The latter in attracting its armature r1 opens the normally closed switch-points in the connection between the battery and the line, thereby giving a free circuit for the projection of the ringing current. r1`he energization of the supervisory relay R5 causes its armature to close a local circuit from the battery through the conductors 31 and 54, through the armature 55, contact point 5G and the conductor 57, through the lamp 58, through conductors 59 and 30, and through conductor 2 to said battery. rlhs lights the supervisory lamp 58, and the said lamp remains lighted until the called for subscriber answers the call. When the subscriber at substation B removes the receiver from the hook-switch, a line circuit is completed from the battery through conductors 2 and 30, through the winding 43 of the repeating coil, through conductor 44, through the coil 45 ot the relay. R5, through the conductor 46, through the key spring 47 and the cord strand 48, thence through the plug tip 49 and the jack spring 60, through the line conductor (3G, through the hook-switch 65 and the contact point 64, thence through the receiver 63 and the transmitter' 62, through the line conductor 61 and the ring or thimble 67 of the jack, through sleeve contact 68 et the plug, through cord strand 66, through key-springiO and'conductor 71 and key-spring '72, through contact point 73 and conductor 74, thence through the coil 7 5 of the supervisory relay RG, through the winding 76 of the repeating coil, through conductors 77, 31 and 14 to the said battery. This, it will be seen, energizes the relay RG, causing the latter to attract its armature and close a normally open shunt around the relay t5. This shunt, it will be seen, consists of a conductor 78, arn'iature 79, contact point 8() and conductor 81. The closing ot this shunt causes the relay R5 to release its armature, thereby opening the switch-point in the circuit of the lamp 58, and thus eX- tinguishing the latter and advising the operator that the called tor subscriber has answered the call. The answering of the call at the sub-station B does not energize the line relay R7, inasmuch as the connection between the battery and the line has already been severed in the manner described. With both plugs insert-ed, and with both receivers removed from the hooks at the substations,

the subscribers can communicate with each other, the talking circuit consisting of the lines and the strands of the cord circuit. l,Vhile the subscribers are talking, the current is furnished to the lines through repeating coils in the cord circuit. Vihen the subscribers hang up the receivers at the sub-stations, relays R3 and RG are denergized, and release their armatures. Said armatures when released open t-he normally open shunts around relays R2 and R5, thereby allo-wing the latter to become energized. The said supervisory relays R2 and when energized, close the normally open switchpoints in the circuits of the supervisory lamps and cause the latter to glow and attract the attention of the central operator. Acting upon these signals, the central operator then withdraws the plugs of the cord circuit, and the system is then in its normal or disconnected condition, as shown in the drawing. Thus it will be seen that the circuit arrangement for operating the lines or" the supervisory signals is simple and efficient. At the saine time, the arrangement is characterized by substantially all ot the approved methods of operation. lt will be readily understood that the resistance of the various coils and relays can be readily adjusted or regulated by those skilled in the art, and in accordance with the conditions of any particular case.

The cut-out relays are, it will be observed, advantageously energized through derived circuits including ditterentportions of the cord circuit connections. in this way each derived circuit operates to hold the cut-out relay in operation as long as the plug is in the jack. f

That I claim as my invention is:

1. ln a telephone system, the combination of a subscriber-s line, a battery connected with the line through a normally closed switch, a line lamp signal, a line relay tor controlling the circuit of said line lamp signal, a cut-out relay arranged to operate said switch, a jack connected with the line, a plug and a cord circuit, a supervisory lamp and a supervisory relay associated with the cord circuit, one terminal of said cut-out relay being permanently connected with the battery, the other terminal of said relay being permanently connected with a tip Contact of said jack, and the local circuit for said cut-out relay being closed by the insertion of the plug in the jack and including said supervisory relay.

2. ln a telephone system, the combination of a subscribers line, a central source ot current supply connected with the line through a normally closed switch, a line lamp signal, a line relay for controlling the circuit of said line lamp signal, a cut-out relay arranged to control said switch, a jack having tip and sleeve contacts connected with the subscribers line, said jack also having a second tip contact connected with one terminal of said cut-out relay, the other terminal of the cut-out relay being permanently connected with said source of current supply, a plug and a cord circuit, and a supervisory lamp and supervisory relay associated with said cord circuit, the local circuit of said cut-out relay being closed by the insertion oit' the plug in the jack, and said local circuit including said supervisory relay.

3. In a telephone system, the combination of a subscribers line, a central source of current supply connected with the line, a jack connected with the line, a plug and a cord circuit, suitable connections for supplying current from the central source of supply through the strands of the cord circuits and the registering contacts of the plug and jack to said line, a supervisory relay in each strand of the cord circuit, a supervisory lamp having a circuit cont-rolled by one ot' said supervisory relays, a normally open shimt around the relay arranged to control the circuit of the supervisory lamp, said shunt being controlled by the other supervisory relay, a line lamp signal, a line relay for controlling the circuit of said line lamp signal, and a cut-out relay :tor severing the connection between said source of current supply and the said line, the circuit for said cut-out relay including tip contacts of a jack and plug, and also including the supervisory relay which controls the circuit of the supervisory lamp.

4. A telephone system comprising a line signal and a line relay for operating the same, a cut-out relay for denergizing said line relay, a supervisory relay, a source of current supply with suitable connection for energizing all of the said relays, and a plug switch for closing the circuit ot said cut-out relay, said switch having a plurality of tip contacts in the jack, so as to restore the line signal, the circuit of said cut-out relay including tip contacts of said switch.

5. In a telephone exchange system, telephone lines, a cord circuit, a pair of supervisory relays included in said circuit, one at each side thereof, a shunt or short circuit extending around one relay, controlled by the other relay, and a supervisory signal controlled by the one relay.

6. In a telephone exchange system, telephone lines, a cord circuit, a pair ot' supervisory relays included in said circuit, one at each side thereof, a shunt or short circuit extending around one relay, controlled by the other relay, and a supervisory signal controlled by the one relay, together with repeating coils included in the talking circuit, and energizing circuits for said relays, each energizing circuit including a repeating coil winding.

7. In a telephone exchange system, a cutoff relay for a telephone line, a supervisory relay, an energizing circuit including the two relays in series, a short circuit around said supervisory relay also included in said circuit, and a jack permanently connected with the line, said relays all energized over circuits including portions of the talking circuit.

8. The combination with a switchboard having terminal plugs provided with a plurality of switch contacts, and containing two conductors electrically uniting corresponding contacts of said plugs, a source of current in a bridge between said conductors, and two signal devices associated with said plugs respectively, of relay mechanism in the circuits of said conductors and source of current controlling the current supplied to said signaling devices, and two relays in circuit with the said cord conductors one on either side of the said bridge, of shunt circuits controlling said signals and controlled by said two relays, thereby determining the display or withdrawal of said signals, substantially as set forth.

9. In a telephone system, a line, a relay, a normally open short circuit around said relay, a second relay for closing said shunt, a line circuit for energizing the said second relay, a local circuit for energizing the first mentioned relay, when connection is made to said line, and means for supplying battery current to the windings of both the said relays and to the said line.

10. In atelephone system, a line, a relay, a normally open short circuit around said relay, a second relay for closing said shunt, a line circuit for energizing the said second relay, means for supplying battery current to the windings of both the said relays and to the said line, a line signal, and a cut off relay having its winding included in said local circuit.

l1. In a telephone system, the combination of calling and called telephone lines, an operators cord circuit Jfor connecting said lines, a pair of relays for each end of said cord circuit, one member of each pair of relays having a normally open shunt controlled by the other relay thereof, and a supervisory lamp for each pair of relays, said relays all energized over circuits including portions of the talking circuit.

12. In a telephone system, a line, a pair of relays, a normally open shunt around one relay cont-rolled by the other relay, a local circuit for energizing the one relay, and a line circuit for the other or shunt controlling relay, said line circuit including the windings of the shunt controlling relay and the shunt around the other relay in series.

13. In a telephone system, a pair of relays, a line signal, a shunt around one relay controlled by the other relay, a cut-oii relay for retiring the line signal, and a local circuit for energizing said cut-oit relay in series with the winding of the shunted relay, said relays all energized over circuits including portions of the talking circuit.

14. A telephone system comprising a telephone line, a source of current and a relay between the two limbs ot' said line, the source of current in bridge of the talking circuit, a second relay and means for energizing it, a switch at the substation and a switch at the central station for controlling the circuit through said relays, a signal controlled by the conjoint action of said relays, and a line signal cut-od1 relay for each line energized in series with one of said relays.

15. A telephone system comprising a telephone line, of a source of current and a relay between the two limbs of said line, whereby the source of current is in bridge of the talking circuit, a second relay and means for energizing it, a switch at the substation for controlling said bridged relay and a switch at the central oflice for controlling said other relay, a signal controlled by the conjoint action of said relays, and a line signal cut-oitz relay for each line energized in series with one of said relays.

16. A telephone system comprising a telephone line, of a source of current and an electro-magnet between the two limbs of said line, whereby the source of current is in bridge ofthe talking circuit, a second electro-magnet and means for energizing it, a switch at the substation and a switch at the central station for controlling the circuit through said electro-magnets, a supervisory signal controlled by the joint action of said electro-magnets, and a line signal cut-oill relay for each line energized in series with one of said relays.

17. A telephone line, a source of electricity and a pair of relays between the limbs of said line, whereby the source of current is in bridge of the talking circuit, a switch at the substation and a switch at the central station for controlling the circuit through said relays, a signal adapted to be controlled by the conjoint action of said relays, and a line signal out-oil relay for each line energized in series with one of said relays.

18. A telephone system comprising a pair of telephone lines, an inductive device through which the same areadapted to be united for conversation, a charging source of electricity and two pairs of relays between the two limbs of said lines, whereby the source of current is in bridge ot the talking circuit, one pair of relays being individual to one of said lines and the other pair being individual to the other line, switches at the substations and at the central station for controlling the circuit through said rclays, a signal controlled by the conjoint action of each pair of relays, and a line signal cut-oil relay for each line energized in series with one of said relays.

19. In a telephone system, a metallic telephone line, an operators plug and a cord circuit, a source of current and a pair of relays placed by the cord circuit between the terminals of said line, a third conductor connected with one pole of said source, one of said relays being adapted to be operated over the metallic line when the subscribers telephone is in use, and t-he other to be operated over a part of the line and said third conductor when the subscribers telephone is not in use and the operators plug is connected with the line, and a line signalcutoit relay for each line energized in series with one of said relays. i

20. In a telephone system, a telephone line, a source of current and a relay inserted between the two limbs of said line, to bridge the source of current across the talking circuit, a second relay at the central oflice and connected with one side of the talking circuit and means for energizing it, a switch at the substation and a switch at the central station for controlling the circuit through said relays, a signal controlled by the conjoint action of said relays,-and a line signal cut-off relay for each line energized in series with one of said relays.

21. In a telephone system, a telephone line, a source of electricity at the central oiiice, an operators plug and a pair of relays associated therewith, one of said relays being energized from the said source of electricity while the plug is connected with the said line and over a path having a part coincident with the talking circuit, and the other relay being energized while the plug is connected with the said line and the subscribers telephone is in use, a signal associated with said pair of relays, the circuit of said signal being established by the operation of the first of said relays and said signal being rendered inoperative by the operation of the second of said relays, and a line signal cut-off relay for each line energized in series with one of said relays.

22. In a telephone exchange system, telephone lines extending from substations to an exchange, each of said substations being provided with a telephone switch hook for supporting the receiver thereat. a common battery at the exchange, supervisory signals located at the exchange, corresponding to calling and called subscribers stations, supervisory relays at the exchange, one for each of the supervisory signals, means whereby the switch hooks at the subscribers stations are adapted to operate each of said relays independently of the other to actuate the corresponding indicator, a second supervisory relay associated with each supervisory signal adapted through the agency of the switch hooks to restore the supervisory signals each independently of the other, means whereby the latter relays are both actuated independently of each other by the said switch hooks, and a line signal cut-oliE relay for each line energized in series with one of said relays, said relays all energized over circuits including portions of the talking circuit.

23. In a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby through the agency of the substation apparatus, a local circuit for each telephone line to include the said source of current in a local circuit, one relay of each pair that is controlled by a subscribers station apparatus being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays cooperating place the supervisory signal in another condition of use, and a line signa-l cut-oli relay for each line energized in series with one of said relays.

2li. ln a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, switching apparatus for controlling the operation of the relays, a reactive device included in each cord strand between the connections of the relays therewith, and a line signal cut-ott relay for each line energized in series with one of said relays.

25. In a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming' connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, a local circuit for each telephone line to include the said source of current in a local circuit, one relay of each pair being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays coperating place the supervisory signal in another condition of use, and a line signal cut-olf relay for each line energized in series withone of said relays.

26. ln a telephone system, telephonelines extending from substations to jacks at an exchange, a cord circuit at the exchange provided with two strands for forming connections between subscriberslines, a pair of relays corresponding to each end of the cord circuit, a source ot' current for energizing the said relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, switching mechanism at the substations for controlling the operation ot one ot each pair of relays, means including a jack and a cord circuit plug inserted in the jack, whereby a closed circuit is established through the remaining relay of each pair which is independent of the operative position ot the substation apparatus, areactive device included in each cord strand between the connections of the relays therei with, and a line signal cut-oilE relay for each line energized in series with one of said relays.

27. A. telephone system comprising a telephone line, a source of current and a relay inserted between the two limbs of said line, a second relay and means for energizing it over a circuit including part of the talking circuit, a switch at. the substation and a switch at the central station for controlling the circuit through said relays, a signal controlled by the conjoint action of said relays, a line signal, and means whereby the flow of current in one of said relays serves to retire the said line signal.

28. A telephone system comprising a telephone line, a source of current and a relay inserted between the terminals of the two limbs of said line, a second relay and means for energizing it over a circuit including part of the talking circuit, a switch at the substation for controlling said bridged relay and a switch at the central otlice for controlling said other relay, a signal controlled by the conjoint action of said relays, a line signal, and means whereby the flow of cur` rent in one'of said relays serves to retire the said line signal.

29. A telephone system comprising a telephone line, a source of current and an electromagnet inserted between the terminals of the two limbs of said line, a second electromagnet and means for energizing it over a circuit including part of the talking circuit, a switch at the substation and a switch at the central station for controlling the circuit through said electro-magnets, a supervisory signal controlled by the joint action of said electro-magnets, a line signal, and means whereby the flow of current in one of said relays serves to retire the said line signal.

30. A telephone line comprising a source of electricity and a pair of relays adapted to be inserted between the limbs of said line, to place the source of current in bridge of the talking circuit, a switch at the substation and a switch at the central station for controlling the circuit through said relays, a signal adapted to be cont-rolled by t-he conjoint action of said relays, a line signal, and means whereby the flow of current in one of said relays serves to retire the said line signal.

3l. A telephone system comprising a pair of telephone lines, an inductive device through which the same are adapted to be united for conversation, a charging source ot electricity and a pair of relays adapted to be inserted between the two limbs of each of said lines, to place the source of current in bridge of the talking circuit, one pair of relays being individual to one of said lines and the other pair being individual to the other line, switches at the substations and at the central station for controlling the circuitthro-ugh said relays, a signal controlled by the conjoint action oi each pair of relays, a line signal, and means whereby the flow ot current in one of said relays serves to retire the said line signal.

32. In a telephone system, a metallic telephone line, an operators plug and a cord circuit, a source of current and a pair of relays bridged by the cord circuit between the limbs ot said line, a third conductor `connected with one pole of said source, one of said relays being adapted to be operated over the metallic line when the subscribers telephone is in use, and the other to be operated over a part of the line and said third conductor when the subscribers telephone is not in use and the operators plug is connected with the line, a line signal, and means whereby the flow of current in one of said relays serves to retire the said line signal.

33. ln a telephone system, a telephone line, a source of current and a relay bridged between the terminals of the two limbs of said line, a second relay at the central oiiice and connected with one side of the talking circuit and means for energizing it, a switch at the substation and a switch at the central station for controlling the circuit through said relays, a signal controlled by the con joint action of said relays, a line signal, and means whereby the flow of current in one of said relays serves to retire the said line signal,

34. In a telephone system, a telephone. line, a source of electricity at the central otlice, an operators plug and a pair of relays associated therewith, one of said relays being energized from the said source ot electricity while the plug is connected with the said line and over a path having a part coincident with the talking circuit, and the other relay being energized while the plug is connected with the saidline and the subscribers telephone is in use, a signal associated with said pair of relays, the circuit of said signal being established by the operation of the first of said relays and said signal being renderedinoperative by the operation of the second ot said relays, a line signal, and means whereby the flow ot current in one of said relays serves to retire the said line signal.

35. In a telephone exchange system, telephone lines extending from substations to an exchange, each of said substat-i ons being pro vided with a telephone switch hook for supporting the receiver thereat, a common battery at the exchange, supervisory signals located at the exchange, corresponding to calling and called subscribers stations, supervisory relays at the exchange, one for each of the supervisory signals, means whereby the switch hooks at the subscribers stations are adapted to operate each of said relays independently of the other to actuate the corresponding indicator, a second supervisory relay associated with each supervisory signal adapted through the agency of the switch hoo-ks to restore the supervisory signals each independently of the other, means whereby the latter relays are both actuated independently of each other by the said switch hooks, a line signal, and means whereby the flow of current in one of said relays serves to retire the said line signal, said relays all energized over circuits including portions of the talking circuit.

36. In a telephone system, telephone lines extending from subscribers7 stations to an exchange, a cord circuit at the exchange provided with two strands tor forming connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs ot relays, connected in bridge oi the talking circuit, a supervisory signal for each pair ofrelays and jointly controlled'thereby through the agency of the substation apparatus, a local circuit for each telephone line to include the said source of current in a local circuit, one relay ot each pair that is controlled by a subscribers station apparatus being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays coperating place the supervisory signal in another condition of use, a line signal, and means whereby the iiow of current in one of said relays serves to retire the said line signal. y

37. In a telephone system, telephone lines extending from subscribers stations to an ex change, a cord circuit at the exchange pro- Clt vided with two strands for forming connections, between two telephone lines, a pair of relays corresponding to each end ot' the cord circuit, a source of current for inclusion in' circuit with each o t said pairs of relays, connected in bridge ot' the t-alking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, switching apparat-us for controlling the operation of the relays, a reactive device included in each cord st-rand between the connections of the relays therewith, a line signal, and means whereby the iow of current in one of said relays serves to retire the said line signal.

38. 1n a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming connections between two telephone lines, a pair ot relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, a local circuit t'or each telephone line to include the said source of current in a local circuit, one relay of each pair being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays cooperating place the supervisory signal in another condition of use, a line signal, and means whereby the iiow of current in one of said relays serves to retire the said line signal.

39. In a telephone system, telephone lines extending from substations to jacks at an exchange, a cord circuit at the exchange provided with two strands for forming connections between subscribers lines, a pair of relays corresponding to each end of the cord circuit, a source ot' current for energizing the said relays, connected in bridge of the talking circuit, a supervisory signal for each pair ot relays and jointly controlled thereby, switching mechanism at the substations for controlling the operation of one of each pair of relays, means including a jack and a cord circuit plug inserted in the jack, whereby a closed circuit is established through the remaining relay of each pair which is independent ot the operative position of the substation apparatus, a reactive device included in each cord strand between the connections of. the relays therewith., a line signal, and means whereby the flow of current in one of said relays serves to retire the said line signal.

l0. A telephone system comprising a telephone line, a source of current and a relay inserted between the terminals of the two limbs ot said line, a second relay and means for energizing it over a circuit including part of the talking circuit, a switch at the substation and a switch at the central stat-ion for controlling the circuit through said relays, a signal controlled by the conjoint action of said relays, and means for rin-ging over the two sides of the called line in series.

4l. A telephone system comprising a telephone line, a source of current and a relay inserted between the terminals of the two limbs et said line, a second relay and means for energizing it over a circuit including part ot' the talking circuit, a switch at the substation for controlling said bridged relay and a switch at the central otlice for controlling said other relay, a signal controlledV by the conjoint action of said relays, and means for ringing over the two sides of the called line in series. f

42. A telephone system comprising a telephone line, a source of current and an electro-magnet inserted between the terminals of the two limbs ot said line, a second electro-magnet and means for energizing it over a circuit including part of the talking circuit, a switch at the substation and a switch at the central station for controlling the circuit through said electro-magnets, a supervisory signal controlled by the joint action of said electro-magnets, and means for ringing over the two sides of the called line in series.

43. A telephone line comprising a source of electricity and a pair of relays adapted to be placed between the terminals ot the two limbs of said line, a switch at the substation and a switch at the central station tor controlling the circuit through said relays, a signal adapted to be controlled by the conjoint action of said relays, and means for 'ringing over the two sides of the called line in series.

4A. A telephone system comprising a pair of telephone lines, lan inductive device through which the same are adapted to be united for conversation, a charging source of electricity and two pairs of relays adapted to be placed between the terminals of the two limbs of each of said lines, one pair of relays being individual to one of said lines and the other pair being individual to the other line, switches at the substations and at the central station for controlling the circuit through said relays, a signal controlled by the conjoint action of each pair ot relays, and means for ringing over the two sides of the called line in series. l

15. In a telephone system, a metallic telephone line, an operators plug and a cord circuit, a source of current and a pair of relays bridged by the cord circuit across the terminal of said line, a third conductor connected with one pole of said source, one of said relays being adapted to be operated over the metallic line when the subscribers telephone is in use, and the other to be operated over a part of the line and said third conductor when the subscm'bers telephone is not in use and the operators plug is connected with the line, and means for ringing over the two sides of the called line in series.

46. ln a telephone system, a telephone line, a source or" current and a relay bridged between the two terminals ot' the two limbs of said line, a second relay at the central otlice and connected with one side of the talking circuit and means for energizing it, a switch at the substation and a switch at t-he central station for controlling the circuit through said relays, a signal controlled by the conjoint action of said relays, and means for ringing over the two sides of the called line in series.

47. ln a telephone system, a telephone line, a source of electricity at the central oltice, an operators plug and a pair of relays associated therewith, one of said relays being energized from the said source of electricity while the plug is connected with the said line and over a path having a partcoincident with the talking circuit, and the other relay being energized while the plug is connected with the said line and the subscribers tele-phone is in use, a signal associated with said pair of relays, the circuit of said signal being established by the operation of the first of said relays and said signal being rendered inoperative by the operation of the second o' said relays, and means for ringing over the two sides of the called line in series.

4S. In a telephone exchange system, telephone lines extending from substations to an exchange, each or' said substations being provided with a telephone switch hook for supporting the receiver thereat, a common battery at the exchange, supervisory signals located at the exchange, corresponding to calling and called subscribers stations, supervisory relays at the exchange, one for each of the supervisory signals, means whereby the switch hooks at the subscribers stations are adapted to operate each of said relays independently of the other to actuate the corresponding indicator, a second supervisory relay associated with each supervisory signal adapted through the agency of the switch hooks tc restore the supervisory signals each independently of the other, means whereby vthe latter relays are both actuated independently of each other by the said switch hooks, and means :tor ringing over the two sides of the called line in series, said relays all energized over circuits including portions of the talking circuit.

49. In a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming connections between two telephone lines, a pair et relays corresponding to each end of the cord circuit, a source ot current for inclusion in circuit .vith each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby controlled by a subscriber-s station apparatus, a local circuit for each telephone line to include the said source oi current in a local circuit, one relay of each pair that is cont-rolled by a subscribers station apparatus being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays cooperating place the supervisory signal in another condition o use, and means for ringing over the two sides of the called line in series.

50. In a. telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with tw'o strands for forming connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, switching apparatus for controlling the operation of the relays, a reactive device included in each cord strand between the connections of the relays therewith, and means for ringing over t-he two sides of the called line in series.

5l. In a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected inbridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, a local circuit for each telephone line to include the said source of current in a local circuit, one relay of each pair being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays coperating place the supervisory signal in another condition of use, and means for ringing over the two sides of the called line in series.

52. In a telephone system, telephone lines extending Vfrom substations to jacks at an exchange, a cord circuit at the exchange provided with two strands for forming connections between subscribers lines, a pair of relays corresponding to each end of the cord circuit, a source of current for energizing the said relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, switching mechanism at the substations for controlling the operation of one of each pair of relays, means including a jack and a cord circuit plug inserted in the jack, whereby a closed circuit is established through the remaining relay oit' each pair which is independent ot the operative position of the substation apparatus, a reactive device included in each cord strand between the connections of the relays therewith, and means for ringing over thc two sides of the called line in series.

53. A telephone system comprising a telephone line, a source ot current and a relay connecting together the two limbs o1t` said line, so that the battery is in bridge ot tho talking circuit, a second relay and means for energizing it over a circuit including part of the talking circuit, a switch at the substation and a switch at the central station for controlling the circuit through said relays, a signal controlled by the conjoint action of said relays, and a busy test circuit including one of said relays.

A telephone system comprising a telephone line, a source ot current and a relay connecting together the two limbs of said line, so that the battery is in bridge of the talking circuit, a second relay and means for energizing it over a circuit including part of the talking` circuit, a switch at the substation for controlling' said bridged relay and a switch at the central othce for controlling said other relay, a signal controlled by the conjoint action ot said relays, and a busy test circuit including one of said relays.

A telephone system comprising a telephone line, a source of current and Yan electro-magnet connecting together the two limbs of said line, a second electro-magnet and means for energizing' it over a circuit including part of the talking circuit, a switch at the substation and a switch at the central station for controlling the circuit through said electro-magnets, a supervisory signal controlled by t-he joint action of said electro-magnets, and a busy test circuit including one of said relays.

56. A telephone system comprisinga line, a source of electricity and a pair of relays adapted to be placed between the limbs ot said line, a switch at the substation and a switch at the central station for controlling the circuit through said relays, a signal adapted to be controlled by the conjoint action of said relays, and a busy test circuit including one of said relays.

57. A telephone system comprising apair of telephone lines, an inductive device through which the same are adapted to be united for conversation, a charging source of electricity and a pair of relays adapted to be placed between t-he two limbs of each of said lines, one pair of relays being for one of said lines and the other pair being for the other line, switches at the substations and at the central station for controlling the circuit through said relays, a signal controlled by the conjoint action of each pair of relays, and a busy test circuit including one of said relays.

58. In a telephone system, a metallic telephone line, an operators plug and a cord circuit, a source of current and a pair of relays placed by the cord circuit between the terminals of said line, a third conductor connected with one pole of said source, one of said relays being adapted to be operated over the metallic line when the subscribers telephone is in use, and the other to be operated over a part of the line and said third conductor when the subscribers telephone is not in use and the operators `,plug is connected with the line, and a busy test circuit including one of said relays.

59. In a telephone system, a telephone line, a source ot current and a relay placed between the two limbs of said line, a second relay at the central ottice and connected with one side of the talking circuit and means for energizing it, a switch at the substation and a switch at the central station for control-V ling the circuit through said relays, a signal controlled by the conjoint action of said relays, and a busy test circuit including one of said relays.

60. In a telephone system, a telephone line, a sourceV of electricity at the central otiice, an operato-rs plug and a pair of relays associated therewith, one ot said relays being energized from the said source of electricity while the plug is connected with the said line and over a path having a part coincident with the talking circuit, and the other relay being energized while the plug is connected with the said line and the subscribers telephone is in use, a signal associated with said pair of relays, the circuit of said signal being established bythe operation of the tirst of said relays and said signal being rendered inoperative by the operation of the second of said relays, and a busy test circuit including one of said relays.

61. In a telephone system, telephone lines extending from substations to an exchange, each of said substations being provided with a telephone switch hook for supporting the receiver thereat, a common battery at the exchange, supervisory signals located at the exchange, Vcorresponding to calling and called subscribers stations, supervisory relays at the exchange, one for each of the supervisory signals, means whereby the switch hooks at the subscribers stationsl are adapted to operate each of said relays independently ot the other to actuate the corresponding indicator, a second supervisory relay associated with each supervisory signal adapted through the agency of the switch hooks to restore thesupervisory signals each independently of the other, means whereby the latter relays are both actuated independently of each other by the said switch hooks, and a busy test circuit including one of said relays.

62. In a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming coni nections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected by the relays in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby through the agency of the substation apparatus, a local circuit for each telephone line to include the said source of current in a local circuit, one relay of each pair that is controlled by a subscribers station apparatus being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays coperating place the supervisory signal in another condition of use, and a busy test circuit including one of said relays.

G3. In a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at the exchange provided with two strands for forming connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, switching apparatus for controlling the operation of the relays, a reactive device included in each cord strand between the connections of the relays therewith, and a busy test circuit including one of said relays.

G4. In a telephone system, telephone lines extending from subscribers stations to an exchange, a cord circuit at. the exchange provided with two strands for forming connections between two telephone lines, a pair ot relays corresponding to each end of the cord circuit, a source of current for inclusion in circuit with each of said pairs ot' relays, connected in bridge ot the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, a local circuit for each telephone line to include the said source of current in a local circuit, one relay of each pair being included in the corresponding local circuit, whereby\ `one relay of each pair may pl'ace the supervisory signal in one condition of use, and both relays coperating place the supervisory signal in another condition of use, and a busy test circuit including one of said relays.

lli.

65. In a telephone system, telephone lines extending from substations to jacks at an exchange, a cord circuit at the exchange provided with two strands for forming connections between subscribers lines, a pair of relays corresponding to each end of the cord circuit, a source of current for energizing the said relays, connected in bridge of the talking circuit, a supervisory signal Jfor each pair ot' relays and jointly controlled thereby, switching mechanism at the substations for controlling the operation of one of each pair of relays, means including a jack and a cord circuit plug inserted in the jack, whereby a closed circuit is established through the remaining relay of each pair which is independent of the operative position of the substation apparatus, a reactive device included in each cord strand between the connections of the relays therewith, and a busy test circuit including one of said relays.

6G. A telephone system comprising a telephone line, a source of current and a relay bridged between the two line terminals of the limbs of said line, a second relay and means for energizing it over a circuit in cluding part of the talking circuit, a switch at the substation for controlling said bridged relay and a switch at the central oiiice for controlling said other relay, and a signal controlled by the conjoint action of said relays.

67. In a telephone system, telephone lines extending from subscribers7 stations to an exchange, a cord circuit at the exchange provided with two strands for forming connections between two telephone lines, a pair of relays corresponding to each end of the cord circuit, a source of current for inclu sion in circuit with each of said pairs of relays, connected in bridge of the talking circuit, a supervisory signal for each pair of relays and jointly controlled thereby, and a local circuit for each telephone line to include the said source of current in a local circuit, one relay of each pair being included in the corresponding local circuit, whereby one relay of each pair may place the supervisory signal in one condition of use, and both relays cooperating place the supervt sory signal in another condition of use.

68. In a telephone system, the combination with a pair of telephone lines, of a cord circuit to connect said lines for conversation, calling and answering supervisory signals for said cord circuit, tour relays, one located in each end of each talking strand of the cord circuit, the circuit of each of said signals being completed through contacts controlled by two ot said relays, switches under the control of the operator in the circuit of two of said relays, the actuation of said relays being adapted to close the circuits of said supervisory signals, switches under the control of the subscribers in the circuits of the other two of said relays, said relays being adapted when actuated to open the circuits of said supervisory signals, substantially as described.

69. ln a telephone system, the combination with a pair of telephone lines, oil a cord cil-crit te connect said lines for conversation, calling and answering supervisory signals for said cord circuit, four relays, one l0- cated in each end of each talking` strand of the cord circuit, switches under the control of the operator in the Circuit of two of said relays, the actuation of said relays being` Signed by nie at Atlantic City, Atlantic county, New Jersey, this 1st day of `arch CHARLES L. GOODRUM.

vWitnesses z ARTHUR VRIGHT, J. S. CARRINTH.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of atents. Washington, D. C.

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