US958627A - Telephone system. - Google Patents

Description

O. L. GOODRUM. TELEPHONE SYSTEM.

APPLIOATION FILED MAE. 15,1902,

Patented May '17, 1910.

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. CHARLES L. GOODRUM, 0F ATLANTIC CITY, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO 0. P. BUR-NS, OF CHICAGO, ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented May 17, 1910.

Application filed March 15, 1902. Serial No. 98,303.

To all whom it may concern:

Be it known that 1, CHARLES L. GooDRUM, a citizen of the United States of America, and resident of Atlantic City, Atlantic county, New Jersey, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

My invention relates more particularly to telephone systems of the complete metallic circuit and central energy type. In telephone systems of this character it is usually the practice to employ complete metallic circuits between the substations and the central exchange, so as to avoid the use of grounded circuits. It is also the practice to operate all of the various instruments and devices fro-1n a common source of current, such as a battery located at the central station. Each subscribers line is connected with what is commonly known as a jack on the switch-board at the central station. The central operator is provided with a cord circuit for connecting up the lines of any two subscribers. This cord-circuit is usually in the form of a cord having two or more strands provided at each end with a plug adapted for insertion in said jacks. Signaling devices are provided whereby the subscribers may attract the attention of the central operator, so as to advise the operator that connection is desired with some other substation. Similar signaling devices are also provided, whereby the central operator may know when the subscribers have finished talking. The signaling devices which respond to the calls from the substations are commonly known as line or calling signals, while the signaling devices which indicate the hanging up of the receivers at the substations are commonly known as supervisory signals. These signaling devices usually consist of small incandescent lamps arranged on the switchboard in front of the central operator. Suitable relays are provided and arranged to close the local circuits of these lamps at the proper times. These relays and lamps are, as previously explained, operated and lighted by current from the battery at the central exchange. In a system of this character the battery also furnishes the current over the lines to the microphone transmitters at the substations.

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

A special object is to provide an improved circuit arrangement and apparatus for controlling and operating the line and supervisory signals.

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

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

The accompanying drawing is a diagram illustrating a telephone system embodying the principles of my invention, it being observed that only two substations, together with line connections and the cord-circuit at the central station, are shown, and it being understood that only such instruments and electrical devices are illustrated as are necessary to a full understanding of the invention.

The general construction and the nature of the telephone system will be readily understood. The sub-station equipments or subscribers apparatus can be of any suitable known or approved character. For examle, it may be of the character shown at substations A and B, these sub-stations being connected with the switchboard at the central station by means of wires or complete metallic line connections. Also, as is usually the case, the subscribers lines terminate, as shown, in spring jacks on the switchboard at the central station. Furthermore, the switchboard apparatus at the exchange or central station includes the usual cords provided with plugs adapted for insertion in the spring jacks, so as to connect one subscribers line with another. Line signal apparatus is associated with each line, and supervisory signal apparatus is associated with the operators cord circuit. Also, as a rule, the battery located at the central station or exchange is adapted for supplying the current to the lines for both talking and signaling purposes. Preferably, small incandescent lamps, controlled by the line or supervisory relays, as illustrated, are employed as the line and supervisory signals. The nature of the different circuit connections, and the functions of the various devices, will, however, be more clearly understood by considering the method employed for connecting up one subscriber with another.

As thus illustrated, and assuming that the subscriber at substation A desires connection with substation B, the circuit connections and operations which then take place are as follows: lVhen the subscriber at substation A removes the receiver from the hook-switch, a line circuit is thereby closed from the common battery 1 at the central station, through the battery lead 2, through the impedance coil 3, thence through the line conductor 4, through the transmitter 5 and the receiver (3 at the substation, through the contact point 7 and the hook-switch 8, thence through the other line conductor 9, through the coil 10 of the line relay R, and through the other battery lead 11, to said battery. This, it will be seen, energizes the line relay R, and causes the latter to attract its armature. The said armature when attracted closes a short local circuit from the said battery through the conductors 2 and 12, through the armature 13 and the contact point 14, thence through the conductor 15 and the line lamp signal 16, and through conductors 17 and 11 to said battery. This lights the lamp 16, and advises the central operator of the call. The said operator then inserts the answering plug P of the cordcircuit in the jack J. This closes a line circuit from the battery 1, through the connection 18, through the impedance coil 19, thence through the tip-strand 20 of the cordcircuit, through the plug-tip 21 and the tip spring 22 of the jack, thence through the line 9, the hook-switch 8, contactpoint 7, receiver 6, transmitter 5, line conductor 4, thence through the ring contact spring 23 of said jack, through the ring contact 24 of the plug, through the ring-strand 25 of the cord circuit, thence through conductor 26 and the coil 27 of the supervisory relay R, conductors 28 and 29 and through the conductor 2 to said battery. Preferably, the supervisory relays are of less resistance than the line relays. This, it will be seen, connects the battery with the line through the medium of the cord-circuit and the jack, and provides the current with a path of less resistance than the connection between the battery and the line including the relay R. Consequently, the insertion of the answering plug shunts out the line relay and allows the latter to release its armature. This, it will be seen, extinguishes or restores the line lamp signal 16. It will also be observed that the completion of this circuit through the cord-strands energizes the supervisory relay R, causing the same to attract its armature. At this juncture, the operator presses the usual listening key, so as to bridge the operators talking set across the c0rd-circuit, and in this way establish connection with the calling subscriber. Upon learning the number of the sub-station desired, which, as stated, is assumed to be substation B, the operator then inserts the calling plug P of the cord-circuit in the ack J. The operator also presses the ringing-key and operates the generator, so as to project ringing current on to the line of the called-for subscriber. The current thus projected from the central-station rings the bell at the substation B in the well-known manner. The insertion of the calling plug in this manner completes a circuit from battery 1, through conductors 29 and 30, through the armature 31, contactpoint 32, through conductor 33 and supervisory lamp 34, thence through sleeve-strand 35 of the cord-circuit, through the ring or thimble 36 of the jack J, through the tipspring 37 of the jack, through the tip 38 of the plug, thence through the cord-strand 39 and the winding 40 of the impedance coil, thence through the conductors 18 and 11 to said battery. This lights the supervisory lamp 34, which continues to glow until the called-for subscriber answers the call. hen the called-for subscriber removes the receiver from the hook-switch at sub-station B, a circuit is then completed from the battery 1, through conductors 11 and 18, through the winding 40 of the impedance coil, through the cord-strand 39, through plugtip 38, through jack-spring 37, through the line conductor 41, through the hookswitch 42 and the contact-point 43, through the receiver 44 and the transmitter 45, thence through line conductor 46, through the jack spring 47 and the ring contact 48 of the plug, thence through cord-strand 49, through key spring 50 of the ringing-key, through contact-point 51, through conductors 52 and 53, through the coil 54 of supervisory relay R thence through conductors 30, 29, and 2 to said battery. This energizes the supervisory relay R causing the same to attract its armature 31, and in this way opening up the local circuit of lamp 34. Thus the taking down of the receiver at substation B, automatically extinguishes the supervisory lamp 34, thereby indicating to the central operator that the called-for subscriber has answered the call. lVith both the receivers off the hookswitches at the substations, the subscribers lines are connected, and the subscribers are in position to carry on their conversation. It will be understood that the talking circuit comprises the line conductors and the strands of the cord-circuit. In this way, the subscribers carry on their conversation over a complete metallic circuit including the tip 21, the cord-strand 55, condenser 56, and the other portion of said cord-strand 57 the contact 58 and keyspring 59, cord-strand 60, plug-tip 38, and also including ring contact 48, cord-strand 49, key-spring 50 and contact-point 51, conductors 52 and 61, the condenser 62, and the c(1)nductor 25 and ring contact 24: of the other hen the subscriber at substation A hangs up the receiver, the line-circuit is broken and the supervisory relay R denergized. This relay, releasing its armature, completes a local circuit from the battery 1, through conductors 2, 29 and 28, through the armature 63 and the contact-point 6A, through conductor 65 and lamp 66, thence through cord-strand 67 and the sleeve contact 68. of the plug, through the ring or thimble 69 of the jack, thence through the jack spring 22 and the tip 21 of the plug, through the conductor 20 and the coil 19, thence through 18 and 11 to said battery. This, it will be seen, causes the supervisory lamp 66 to glow, and advises the central operator that the subscriber at substation A is through talking and has hung up the receiver. In a similar manner, when the subscriber at substation B hangs up the receiver, a local circuit is completed through the lamp 34: in the manner already described. Thus the central operator is automatically signaled when the subscribers hang up their receivers, and the operator then withdraws the plugs from the jacks.

It will be understood that the resistance of the various coils and relays can be regulated by those skilled in the art, in accordance with conditions. The supervisory circuit arrangement affords convenient opportunity for the employment of multiple jacks, it being observed that both the answering and the multiple jacks are each provided with but two conductorsthat is to say, that with my improved circuit arrangement there are only two wires or conductors leading from each jack. It will be seen that the rings or thimbles of the jacks not only serve as test rings, so as to permit the operator to make the usual busy test, but also serve to complete circuit connections through the third strand of the cord-circuit. Furthermore, each of these test rings is connected solely with the tip spring of the jack.

When an operator makes a busy test, the tip of one of the calling plugs is placed against the sleeve or testing ring of the jack connected with the line being tested. If this line is closed at the subscribers station, and no plugs are in the jacks thereof, the operators receiver X receives current through the subscribers station. But if another operator has a plug in one of the multiple jacks of the line, then the said receiver X receives current through a supervisory lamp of the other cord-circuit. And, as shown, one terminal or" said receiver X is connected with the sleeve side of the line, while the other terminal is adapted to be temporarily connected with the tip of the plug with which the operator is making the test.

What 1 claim as my invention is:

1. A telephone system comprising substations and a central station and line connection between the same, circuit-changing devices at the substations for closing and opening the line circuits, a source of current at the central station connected with the lines and adapted to furnish current thereto for both talking and signaling purposes, line lamp signals having local clrcuits including said source of current, line relays for controlling said local circuits, jacks connected with the lines, a cord-circuit having plugs adapted for insertion in said jacks, a condenser in each talking strand of the cord-circuit, an impedance coil connected in parallel with one of said condensers, supervisory lamps associated with said cord-circuit, supervisory relays for controlling the circuits of said supervisory lamps, the impedance or retardation in the cordcircuit being in parallel with the line relays when the plugs are inserted, so as to shunt out the line relays and extinguish the line lamp signals, and the said supervisory relays being in series with the impedance or retardation when the plugs are inserted in the jacks.

2. A telephone system comprising substations and a central station and complete metallic line connection between the same, a plurality of jacks connected with each line, a line signal for each line, each jack having a pair of spring contacts and also a testing ring, said testing ring being connected with the line, a central source of current supply adapted to furnish current for both talking and signaling purposes, and a cord-circuit provided with plugs adapted for insertion in said jacks, both the tip and sleeve contacts of each ack being connected to the line-signal side of its allotted line.

3. A telephone system comprising subscribers lines, a plurality of jacks connected with each line, a line signal for each line, each jack having a test ring normally connected solely with the line, and a cord-circuit having three-way plugs provided with sleeve contacts adapted to register with and thereby close suitable circuits through the said testing rings, both the tip and sleeve contacts of each jack being connected to the line-signal side of its allotted line.

a. A telephone system comprising substations and a central station, complete metallic line connection between the same, a pluralit-y of jacks connected with each line, each jack having a testing ring norm-ally connected with the line only, a central source of current supply connected with the lines, a cord-circuit having three-way plugs provided with sleeve contacts adapted to register with said testing rings, and supervisory lamps located in the sleeve strand of the cord circuit.

5. A telephone system comprising substations and a central station, complete metallic line connection between the same, a plurality of jacks connected with the line, each jack having tip and ring contact springs and also a test rin connected with the tip spring, a centrf source of current supply connected with the lines, a cord circuit having three-way plugs provided with sleeve contacts adapted to register with said test rings, a condenser in each talking strand of the cord circuit, supervisory lamps located in the sleeve strand of the cord-circuit, and suitable impedance means arranged in parallel with one of said condensers and connected with said source of current supply.

6. In a telephone system, the combination of a subscribers line, a jack having three contacts, a source of current connected with the line, a cord-circuit provided with a plug having three contacts the contacts of the plug being adapted to engage the contacts of the jack, a supervisory lamp suitably associated with said cord-circuit, and a local circuit for said supervisory lamp including two of the jack contacts and also two of the plug contacts.

7. In a telephone system, the combination of the subscribers line, a jack connected with the line, a source of current connected with the line, a cord-circuit provided with a plug adapted for insertion in said jack, said jack and plug having registering con tacts, and a supervisory lamp associated with the cord-circuit, the local circuit of said supervisory lamp including a plurality of jack contacts and also a plurality of plug contacts, whereby said lamp is excluded from the talking circuit.

8. In a telephone system, the combination of subscribers lines, a plurality of acks connected with each line, each jack being pro vided with a testing ring connected with one side of the line, a source of current supply connected with the lines, an operators cord circuit having three-way plugs adapted for insertion in said jacks supervisory lamps located in the sleeve strand of said cord-circuit, the localcircuit of each supervisory lamp including one of said testing rings, line relays and line signals controlled ther by, and cord-circuit connections for shunting out said line relays.

9. In a telephone system, the combination of a subscribers line, a plurality of jacks connected with said line, each jack having but two wires or connections lea-ding thereto, a cord-circuit having a plug adapted for insertion in said jacks, a central source of current supply adapted to furnish current for both talking and signaling purposes, a line signal and a line relay, a circuit-changing device for closing the line circuitand thereby operating said line signal, a supervising signal connected and arranged to be brought into operation by the opening of the line circuit by said circuit changing device, both the tip and sleeve contacts of each jack being connected to the line-signal side of its allotted line, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

10. A complete metallic line circuit and multiple switch-board telephone system comprising subscribers lines, a line signal for and connected in only one side of each line, a plurality of jacks connected with each subscribers line, each jack having but two wires or connections leading thereto, a central source of current supply connectcd with the lines and adapted for furnishing current thereto for both talking and signaling purposes, and a cord-circuit pro vided with plugs adapted for insertion in said jacks, both the tip and sleeve contacts of each jack being connected to the linesignal side of its allotted line, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

11. In a telephone system, the combination of a substation and a central station, complete metallic line connections between the same, a plurality of jacks at the central station connected with each line, each jack having but two wires or connections leading therefrom, a central source of current supply adapted to furnish current for both talking and signaling purposes, hook switches at the substations for opening and closing the line circuits, line lamp signals in local circuits, line relays for controlling the local circuits of said lamp signals, a cord-circuit having plugs adapted for insertion in said jacks, supervisory lamps in local circuits, and supervisory relays for controlling the local circuits of said supervisory lamps, both the tip and sleeve contacts of each jack being connected to the line signal side of its allotted line, together with means for making a busy test. said busy test means including a receiver having one terminal pemanently connected with the sleeve or testing ring side of the line but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

12. A telephone system comprising substations and a central station and complete metallic line connection between the same, a line signal for and connected in only one side of each line, a plurality of jacks consleeve or testing ring side of the line, but

having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

18. A telephone system comprising substations and a central station, complete metallic line connections between the same, a plurality of jacks connected with the line, each jack having tip and ring contact springs, and each jack being also provided with a testing ring connected with the associated tip-spring contact, a central source of current supply connected with the lines and adapted to furnish current thereto for both talking and signaling purposes, and a cord-circuit provided with plugs adapted for insertion in said jacks, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

1a. A telephone system comprising sub stations and a central station, complete metallic line connection between the same, a plurality of jacks connected with each line, each jack having tip, ring and sleeve contacts, each sleeve contact being connected with the tip contact of the ack, a suitable source of current supply connected with the lines and adapted to furnish current thereto for both talking and signaling purposes, and a cord-circuit provided with three-way plugs having tip, ring and sleeve contacts adapted to register with the said contacts of the jacks, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

15. A telephone system comprising subscribers lines, a line signal for and connected in only one side of each line, a plurality of jacks connected with each line, each jack having a test ring normally connected solely with the line, and a cord-circuit having three-way plugs provided with sleeve contacts adapted to register with and thereby close circuits through the said testing rings, both the tip and sleeve contacts of each jack being connected to the line signal side of its allotted line, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

16. A telephone system comprising substations and a central station, complete metallic line connection between the same, a plurality of jacks connected with each line, each jack having a testing ring normally connected with the line only, a central source of current supply connected with the lines, a cord-circuit having three-way plugs provided with sleeve contacts adapted to register with said testing rings, and supervisory lamps located in the sleeve strand of the cord circuit, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

17. A telephone system comprising substations and a central station, complete metallic line connection between the same, a plurality of jacks connected with the line, each, jack having tip and ring contact springs and also a test ring connected with the tip spring, a central source of current supply connected with the lines, a cord-circuit having three-way plugs provided with sleeve contacts adapted to register with said test rings, a condenser in each talking strand of the cord-circuit, supervisory lamps located in the sleeve strand of the cord-circuit, and suitable impedance means arranged in parallel with one of said condensers and connected with said source of current supply, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

18. In a telephone system, the combination of a subscribers line, a jack having three contacts, a source of current connected with the line, a cord-circuit provided with a plug having three contacts, the contacts of the plug being adapted to engage the contacts of the jack, a supervisory lamp associated with said cord-circuit, and a local circuit for said supervisory lamp including two of the jack contacts and also two of the plug contacts, together with means for making a busy test, said busy test means includ ing a receiver having one terminal perma nently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

19. In a telephone system, the combination of the subscribers line, a jack connected with the line, a source of current connected with the line, a cord-circuit provided with a plug adapted for insertion in said jack, said jack and plug having registering contacts, and a supervisory lamp associated with the cord-circuit, the local circuit of said supervisory lamp including a plurality of jack contacts and also a plurality of plug contacts, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other termi nal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test.

20. In a telephone system, the combination of subscribers lines, a plurality of jacks connected with each line, each jack being provided with a testing ring connected with one side of the line, a source of current supply connected with the lines, an operators cord-circuit having three-way plugs adapted for insertion in said jacks, supervisory lamps located in the sleeve strand of said cord-circuit, the local circuit of each supervisory lamp including one of said testing rings, line relays and line signals controlled thereby, and cord-circuit connections for shunting out said line relays, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the tip of the plug with which the operator is making the busy test.

21. A telephone system comprising subscribers lines, a line signal for and connect ed in only one side of each line, suitable line signals, suitable supervisory signaling ap paratus, and a battery adapted to furnish current to the lines for both talking and signaling purposes, both the tip and sleeve contacts of each jack being connected to the line signal side of its allotted line, together with means for making a busy test, said busy test means including a receiver having one terminal permanently connected with the sleeve or testing ring side of the line, but having its other terminal adapted to be temporarily connected with the tip of the plug with which the operator is making the busy test, substantially as shown and described and for the purposes specified.

22. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, a supervisory device and means for energizing it in series with the line and battery and impedance coil, with the battery interposed between the supervisory device and impedance coil, and means for connecting the impedance coil in parallel with the line relay to prevent display of the line signal.

23. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, a supervisory device and means for energizing it in series with the line and battery and impedance coil, with the battery interposed between the supervisory device and impedance coil, and means for connecting the impedance coil in parallel with the line relay to prevent display of-the line signal, said impedance coil permanently connecting the battery with one side of the cord circuit.

24. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, and means for connecting the impedance coil in parallel with the line relay to prevent display of the line signal, a supervisory relay, a supervisory lamp signal controlled by said supervisory relay, a circuit including the battery and supervisory relay in series with the telephone line, and a local circuit including the battery in series with the supervisory lamp signal.

25. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, and means for connecting the impedance coil in parallel with the line relay to prevent display of the line signal, a supervisory relay, a supervisory lamp signal controlled by said supervisory relay. a circuit including the battery and supervisory relay in series with the telephone line, and a local circuit including the battery in series with the supervisory lamp signal, together with an impedance coil connecting the battery with the telephone line and shunted by said supervisory relay when connection is made to line.

r 26. In a telephone exchange system, the

combination of a telephone line, a line relay, a signal controlled by said relay, abattery, a cord circuit having a condenser at each side thereof, an impedance coil connecting the battery with one side of the cord circuit, a plug and jack for causing the impedance coil to shunt the line relay, a supervisory lamp signal, and a local circuit controlled by said plug and jack, through the medium of a plurality of contacts in each, and including the battery and lamp signal 1n SBIIGS.

27. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, a supervisory device and means for energizing it in series with the line and battery and impedance coil, with. the battery interposed between the supervisory device and impedance coil, and means for connecting the impedance coil in parallel with the line relay to prevent display of the line signal, said telephone line provided with a transmitter adapted to receive talking current from said battery.

28. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, a supervisory device and means for energizing it in series with the line and battery and impedance coil, with the battery interposed between the supervisory device and impedance coil, and means for connecting the impedance coil in parallel with the line relay to prevent display of the line signal, said impedance coil permanently connecting the battery with one side of the cord circuit, said telephone line provided with a transmitter adapted to receive talking current from said battery.

29. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, and means for connecting the impedance coil in parallel with the line relay to prevent display of the line signal, a supervisory relay, a supervisory lamp signal controlled by said supervisory relay, a circuit including the battery and supervisory relay in series with the telephone line, and a local circuit including the battery in series with the supervisory lamp signal, said telephone line provided with a trans- Initter adapted to receive talking current from said battery.

30. In a telephone exchange system, the combination of a telephone line, a line relay, a cord circuit having a condenser at each side thereof, a battery, an impedance coil, a line lamp signal controlled by said line relay, means for connecting the line relay and battery in series in the line, and means for connecting the impedance coil in parallel with the line relay to prevent display of the line signal, a supervisory relay, a supervisory lamp signal controlled by said supervisory relay, a circuit including the battery and supervisory relay in series with the telephone line, and a local circuit including the battery in series with the supervisory lamp signal, together with an impedance coil connecting the battery with the telephone line and shunted by said supervisory relay when connection is made to line, said telephone line provided with a transmitter adapted to receive talking current from said battery.

31. In a telephone exchange system, the combination of a telephone line, a line relay, a signal controlled by'said relay, a battery, a cord circuit having a condenser at each side thereof, an impedance coil connecting the battery with one side of the cord circuit, a plug and jack for causing the impedance coil to shunt the line relay, a supervisory lamp signal, a supervisory relay controlling said lamp signal, and a local circuit controlled by said plug and jack and including the battery and lamp signal in series, said telephone line provided with a transmitter adapted to receive talking current from said battery.

32. In a telephone exchange system, the combination of a telephone line, a line relay, an impedance coil for shunting said line relay, a supervisory lamp signal, a supervisory relay controlling said lamp signal, a circuit for said lamp including said impedance coil, means for opening and closing and thus controlling said lamp circuit, a battery for energizing the line relay, and a talking circuit having a condenser at each side thereof.

33. A telephone exchange system including a telephone line, a jack therefor, a cord .circuit for uniting telephone lines in conversat-ion, disconnect signal apparatus including a relay governed by line equipment, and a signal-presenting device governed by the armature of the sald relay and adapted for inclusion in a circuit that contains two normally separated contacts of a plug of said cord circuit, said jack being adapted to connect said contacts of said plug when said plug is inserted, whereby circuit through said signal-presenting device is established in part by the engaged plug and jack.

34. A telephone exchange system including a telephone line, a jack therefor, a cord circuit for uniting telephone lines in conversation, disconnect signal apparatus including a relay governed by line equipment, and a signal-presenting device governed by the armature of the said relay and adapted for inclusion in a circuit that contains two normally separated contacts of a plug of said cord circuit, said jack being adapted to connect said contacts of said plug when said plug is inserted, whereby circuit through said signatpresenting device is established in part by the engaged plug and jack, the armature of said relay when unattracted serving to establish a circuit for said signalpresent-ing device at another point.

35. In a telephone exchange system, the combination of a jack, a plug adapted to be inserted in said jack, a supervisory signal device, and a local energizing circuit for said device, including normally separated con tacts of said plug, whereby said device is excluded from the talking circuit, said jack provided with means therein sufficient for connecting together said contacts to establish said circuit.

36. In a telephone exchange system, the combination of a jack, a plug adapted for insertion in said jack, a lamp, and a local circuit for said lamp, including normally separated contacts of said plug, whereby said device is excluded from the talking circuit, said jack provided with means therein suflicient for connecting together said contacts to establish said circuit.

37. In a telephone exchange system, the combination of a jack, a plug adapted for insertion in said jack, a lamp, a circuit for said lamp including normally separated contacts of said plug, and a relay controlling said circuit, said jack provided with means for connecting together said contacts to establish said circuit.

38. A telephone exchange system including a telephone line, a common battery having both poles thereof permanently connected with opposite sides of said line, a jack for said line, a cord circuit for uniting telephone lines in conversation, disconnect signal apparatus including a relay governed by line equipment, and a signal-presenting device governed by the armature of the said relay and adapted for inclusion ina circuit that contains two normally separated contacts of a plug of said cord circuit, said jack being adapted to connect said contacts of said plug when said plug is inserted, whereby circuit through said signal-presenting device is established in part by the engaged plug and jack.

39. A telephone exchange system including a telephone line, a common battery having both poles thereof permanently connected with opposite sides of said line, a jack for said line, a cord circuit for uniting telephone lines in conversation, disconnect signal apparatus including a relay governed by line equipment, and a signal-presenting device governed by the armature of the said relay and adapted for inclusion in a circuit that contains two normally separated contacts of a plug of said cord circuit, said jack being adapted to connect said contacts of said plug when said plug is inserted, whereby circuit through said signal-presenting device is established in part by the engaged plug and jack, the armature of said relay when unattracted serving to establish a circuit for said signal-presenting device at another point.

40. In a telephone exchange system, the combination of a jack, a common battery permanently connected with said jack, a plug adapted to be inserted in said jack, a supervisory signal device, and a local energizing circuit for said device, including normally separated contacts of said plug, Whereby said device is excluded from the talking circuit, said jack provided with means therein sufi'icient for connecting together said contacts to establish said circuit.

41. In a telephone exchange system, the combination of a jack, a common battery permanently connected with said jack, a plug adapted for insertion in said jack, a lamp, and a local circuit for said lamp, including normally separated contacts of said plug, whereby said device is excluded from the talking circuit, said jack provided With means therein sufiicient for connecting together said contacts to establish said circuit.

42. In a telephone exchange system, the combination of a jack, a common battery permanently connected with said jack, a plug adapted for insertion in said jack, a lamp, a circuit for said lamp including normally separated contacts of said plug, and a relay controlling said circuit, said jack provided with means for connecting together said contacts to establish said circuit.

43. A telephone exchange system including a telephone line, a jack therefor, a cord circuit for uniting telephone lines in conversation, disconnect signal apparatus including a relay governed by line equipment, a signal-presenting device governed by the armature of the said relay and adapted for inclusion in a local circuit that contains two normally separated contacts of a plug of said cord circuit, and a line signal device adapted to be shunted by a portion of said local circuit to retire the line signal, said jack being adapted to connect said contacts of said plug when said plug is inserted, whereby circuit through said s1gnal-presenting device is established in part by the engaged plug and jack.

l i. A telephone exchange system including a telephone line, a jack therefor, a cord circuit for uniting telephone lines in conversation, disconnect signal apparatus including a relay governed by line equipment, a signal-presenting device governed by the armature of the said relay and adapted for inclusion in a local circuit that contains two normally separated contacts of a plug of said cord circuit, and a line signal device adapted to be shunted by a portion of said local circuit to retire the line signal, said jack being adapted to connect said contacts of said plug when said plug is inserted, whereby circuit through said signal-presenting device is established in part by the engaged plug and jack, the armature of said relay when unattracted serving to establish a circuit for said signal-presenting device at another point.

4.5. In a telephone exchange system, the combination of a jack, a plug adapted to be inserted in said jack, a supervisory signal device, a local energizing circuit for said device, including normally separated contacts of said plug, whereby said device is excluded from the talking circuit, said jack provided with means therein sufiicient for connecting together said contacts to establish said circuit, and a line signal device adapted to be shunted by a portion of said circuit to retire the line signal.

@6. In a telephone exchange system, the combination of a jack, a plug adapted for insertion in said jack, a lamp, a local circuit for said lamp, including normally sepa rated contacts of said plug, whereby said device is excluded from the talking circuit, said jack provided with means therein suflicient for connecting together said contacts to establish said circuit, and a line signal device adapted to be shunted by a portion of said circuit to retire the line signal.

47. In a telephone exchange system, the combination of a jack, a plug adapted for insertion in said jack, a lamp, a local circuit for said lamp including normally separated contacts of said plug, whereby said device is excluded from the talking circuit, a relay controlling said circuit, said jack provided with means therein suflicient for connecting together said contacts to establish said circuit, and a line signal device adapted to be shunted by a portion of said circuit to retire the line signal.

48. In a telephone system, a spring jack having only two wires leading thereto, a line signal device, means for shunting said line signal device to retire the same in answering a call, a supervisory signal device, and a local circuit for said supervisory device including two contacts of said jack.

4:9. In a telephone system, a spring jack having only two conductors leading thereto, a line signal device, means for shunting said line signal device to retire the same in answering a call, a plug adapted for insertion in said jack, a supervisory signal device, and a local circuit for said supervisory device, said circuit including two contacts of the jack and two contacts of the said plug.

50. In a telephone system a spring jack having only two conductors leading thereto, and a local circuit for a supervisory signal device, whereby said device is excluded from the talking circuit, said circuit including two contacts of the jack and two contacts of the plug inserted therein.

51. In a telephone system, a supervisory signal device, and a local circuit for said device including two normally separated contacts of a plug, whereby said device is excluded from the talking circuit, substantially as disclosed.

Signed by me at Atlantic City, Atlantic county, New Jersey, this first day of March, 1902.

CHARLES L. GOODRUM.

Witnesses:

ARTHUR WRIGHT, J. S. OARBUTH.

It is hereby certified that in Letters Patent No. 958,627, granted May 17, 1910, upon the application of Charles L. Goodruni, of Atlantic City, New Jersey, for an improvement in Telephone Systems, the name of the assignee was erroneously written and printed C. P. Burns, whereas said name should have been written and printed P. 6. Burns; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 30th day of August, A. D., 1910.

[SEAL] F. A. TENN AN T,

Acting Commissioner 0 f Patents.

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