US1071207A - Telephone system. - Google Patents

Description

E. a. @www ai A. BALSE TELBPEGNE SYSTEM.

El) SEPT.17,198. RENRWED AUG. 14, l9l.

Payented Aug. 26, 1913.

Y,v H,

A 0 w I l n w N NN o E o 2Q,

UNITED STATES PATENT OFFICE.

ELMER R. CORWIN AND CHARLES A. BALS, OF CHICAGO, ILLINOIS, ASSIGNORS TO CORWINHFELEPHONE MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A COR- PORATION 0F ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters luatent.

Patented Aug. 26,1913.

Application filed September 17, 1908, Serial No. 453,541. Renewed August 14, 1911. Serial No. 644,043.

To all whom it may concern:

Be it known that we, ELMER R. CORWIN and CHARLES A. BALS, cit-izens ofthe United States of America, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Telephone System, of which the following is a specification, reference being had to the accompanying drawing, illustrating same.

Our invention relates to telephone systems having automatic calling mechanism and automatic operators-control mechanism.

The principal objects of our invention are,

to provide improved means for automatically calling subscribers when connection is made with their lines; to provide improved means for automatically controlling such calling apparatus; to provide improved means for controlling the operators connection with the various cord circuits of the system; and to provide other improved circuit arrangements hereinafter described.

The accompanying drawing is a diagrammatic illustration of a pair of telephone lines extending from substations to a central eX- change, and a connecting circuit for the lilies having the necessary apparatus associated therewith for operating the system in accordance with this invention.

The line of subscriber A extends in two limbs 1 and 2 to suitable connection terminals 3 and 4, respectively, of a spring jack C at the central exchange. Terminals 3 4 normally engage contactsl 5 6, respectively, but are adapted to disengage these contacts when a plug is inserted into the jack. Contact 5 extends through a line lamp T to the live pole 8 of battery D, the opposite pole 9 of battery D being grounded. Contact 6 is connected direct to ground, as is also the thimble 10 of the jack C. At the substation A. limb 2 of the line is normally7 connected through ringer 11 and a condenser 12 to ground, this connection to ground being broken when the. receiver' is removed from the switch-hook .13 in the ordinary manner. Substation A also contains the ordinary talking apparatus. The line of subscriber B is similar to line A and like characters have been used to represent like parts in connection with the two lines.

In the plug-cord connecting circuit the answering plug l'l and the calling plug F have their tip contacts 14 14 and ring contacts l5 15 connected together, respectively,

through respective condensers 16 1T, these strands through the plug-cord circuit constituting the metallic talking circuit through the connecting circuitwhen the connecting plugs E and F are connected with lines. The plugsE and F have their sleeve contacts 18 18 connected through respective windings 19 and 2O of an operators differential relay H to pole' 8 of battery D. The windings of this relay are so arranged that when either one of the connecting plugs E F is connected with a line the relay will be energized and will thereby connect the operators telephone set with the corresponding connecting circuit. the operator`s telephone set beingv normally disconnected from the connecting `circuit at contacts 21 22 and 23 24 which are controlled by the relay H, and the battery circuit of the operators transmitter 25 being normally open at contact- 26 2T which is also controlled by relay H. The windings of relay H are also arranged so that when both of the connecting plugs E and F are connected with lines the relay H is deneigized.` under these conditions the windings 19 and 2O of relay H acting differentially. Therefore it will readily be seen that it is inipos sible for the operator to listen in on a connection established between two lines, and that the operators set is controlled by a single relay for each pair of cords before her. J is an impedance coil through which talking battery trom battery D is supplied to the operators transmitter 25.

The answering supervisory lamp 28 is controlled by contact 29 30 which is controlled by relay K. This relay Kelso serves as an impedance to both limbs of the metallic talking circuit. W'hen the calling plug F is connected with a line, relay L becomes energized and thereby closes normally open contacts 31 32 and 33 34. These contacts control the circuits of the ringing generator G and the interrupter M. respectively, as will be hereinafter described. Contact 31 32 is in a limb of the talking circuit. The interrupter M when operated periodicallyy closes and opens a contact 35 36 which is in the circuit of winding 43 of relay N, so that the interrupter M will control the operation of relay N as will` be hereinafter described. The calling supervisory lamp 37 is controlled by a contact 38 39 which is controlled by relay N. Relay N also controls a normally closed contact 40 41 in ythe circuit of ringing generator G, and a; normally open contact 41 4Q in a limb of the talking circuit. lVinding 44 of relay N is connected from a limb of' the plug-cord talking circuit to pele 8 of battery D, and in addition to energizing` the relay N as Will be hereinafter described, it serves as an impedance-to this limb of the talking circuit. lVinding 45 of relay P in addition to energizing relay P as will be hereinafter described, also serves as an in'ipedance to one of the limbs of the talking circuit. Relay P controls a normally closed contact 4G 47 in the circuit of ringing generator (l, a normally closed Contact 48 4t) in the circuit of interrupter M, a normally closed Contact 50 5l in the circuit of winding 43 of relay N, and a normally open Contact 50 .72 in circuit with winding 53 of relay P. The Contact 50 52 is for the purpose of r:ausing relay P to lock itself in operated position from the time the circuit of the line is closed while the calling plug F is connected therewith. until thev plug F is disconnected from the line, for purposes hereinafter' described. The contacts 14, 15 and 18 of each ofthe connecting plugs ll and F register with conta-cts 3, 4 and 10 of a jack C when connection is made with a line.

The operation of the system is Assuming that subscriber A and converse with subscriber B, he first removes his telephone receiver from the switch-hook which closes the circuit of his metallic line through his substation and thereby closes a circuit of battery D through line lamp 7 belonging to line A, and through the metallic line A back to ground at the central station. Current from battery D flowing through lamp 7 which conveys to the operator a signal for connection. The operator then in- /serts the answering plug E into the jack C of line A and by so doing opens jack contacts 3 5 and 4 6 to prevent the line lamp 7 of line A from displaying a signal, and closes 'the following circuits: First. From pole 8 ot battery D through winding 19 of relay H and plug-jack contact 18 10 of line A to ground. Current from battery D flowing through this circuit energizes relay H and thereby causes saine to close contacts 2l 2?. Q3 Q4 and Q6 27, which bridges the iperators telephone set across the metallic plugeord talking circuit and also Supplies tl e operators transmitter 25 with battery Vfrom pole 8 ot' battery l) through inuiedance roil J. contact 27 Q6, and transmitter 25 to ground. Second. From pole 8 of battery D through winding 54 of relay K. thrtmgh the metallic line A. and through winding 55 of relay K to ground. Current from battery D tiowing through this circuit energizes relay K and thereby causes same to open contact 29 30 to prevent the supervisory lamp 28 from displaying a signal. Now the as follows: desires to call this circuit lights the line l l l l g Vthis circuit starts the operator conversos with the party at substation A and finds out from him that the party at substation .B is desired. The operator now inserts the calling plug F into the jack C of line l. which opens jack contacts 3 5 and 4 (3, to prevent the line lamp 7 of line B from displaying a signal, and closes, or causes the closure of, a number of circuits as follows: First. From pole 8 o1 battery D through winding Q0 of relay H, and plug-jack contact 18 l() et' line Il to ground. through this circuit causes relay ll to be come denergized, because winding# 1f) and 20 of relay H now act ditl'erentially, and thereby open contacts 21 22, 23 24 and Q6 27, which disconnects the operators set from the plug-cord talking' circuit and opens the battery circuit through the operators transmitter Second. From pole 8 of battery D through calling supervisor; lamp 37, contact 38 39 of relay N, and plug-jack Contact 18 10 of line B to ground. "Current from battery D flowing through this circuit causes supervisory lamp 37 to display a signal, which indicates to the operator that line B is not taken fer use. Third. From pole 8 ot battery D through the winding of relay L, and plug-jack contact 18 10 of line B to ground. Current from battery D flowing through this Circuit cnergizes relay L and causes it to close contacts 31 32 and 33 34. Fourth. Contact 31 32 being closed closes a, circuit of rii'iging generator Ur through contact 46 47 of relay P. contact 4() 4l 0f relay N, contact 32 31 of relay L, plug-jack Contact 15 4, limb 2 of. line B, ringer '11, and condenser l2 to ground. Current from ringing generator G flowing through this cirv cuit operates the ringer 11 at. substation l and thereby signals the party at substation to answer hisl telephone. Fifth. ContactJ 33 34 being closed closes a circuit from pole 8 of battery D through the armature of interrupter M, contact 48 49 of relay P, contact 34 33 of relay L, and plugjack Contact 18 10 of line B' to ground. Current from battery D flowing through operation of interrupter M and thereby causes it toperiodically close and. open Contact 35 36,as `will be readily understood. Sixth. When contact 35 36 is closed it closes a circuit from pole 8 of battery D through contact 35 36 of the interrupter M, winding 43 of relay N, contact 51 50 of relay P, and plugjaCk..con tact 1S 10 of line B to ground. Current from battery D flowing through this circuit energizes relay N and causes same to open contacts 38 39 and 40 41. and elo-se contact 41 42. Contact 38 39 being open extinguishes the supervisory lamp 37. Contact 40 41 being open stops the flow of current from ringing generator G over line B. Contact 41 42 being closedrcloses a break lurrent from battery D flowing in a limb of the plug-cord talking circuit to complete the continuity ot said talking circuit. In a few seconds the continuous operation ot' the interrnpter M causes contact 35 S6 to again become open, which de energizes relay N and causes it to open contact 41 l2 and close contacts 40 41 and 3S 39. Contact 4() 11 being now closed causes ringing current from ringing generator G to again flow over limb :2 of line B and again ring the. ringer at. substation B. Contact 38 39 being now closed again causes thc supervisory lamp 37 to display a signal. As the operation of the interrupter M continues it causes ringing current to be sent periodically over limb of line B to periodically ring the ringer l1 at substation B, and also causes thc supervisory lamp 3T to give a signal periodically, simultaneously with the ringing of the ringer at substation B, in the manner described above. Then the party at substation B answers his call he removes his receiver from the switch-hook in the usual manner, which closes the circuit between the limbs olf his line and thereby closes a circuit from pole S of battery D through winding 4-1 ot' relay X. contact 12 41 of relay N. contact 3:2 31 of relay L, plugiack contact l5 4 of line B, the metallic line B, plug-jack contact 3 14 of line B, and winding 45 of relay P to ground, provided intcrrupter M has contact 35 36 closed so as to energize relay X and thus cause the latter to have contact 11 42 closed; this condition heilig attained as soon as the interrupter M closes contact 35 S6 after the party at substation B removes his receiver from the switch-hook. if the contact 35 36 is not already closed when the receiver is taken for use. Current flowing through this circuit gives additional energy to relay N and also energizes relay P and causes the latter to open contacts 46 4T. 48 4f) and 50 51, and close contact 50 Contact 46 47 being open prevents the flow of ringing current from ringing generator G over line B. Contact 48 49 being open stops the operation ot' interrupter M, provided the interrupter M is not operated by having its armature circuit closed by apparatus of other cord circuits. Contact.50 51 being open prevents current from flowing through winding 4B of relay N, even if interrupter )l should be still in motion so as to periodically close contact 36. Contact 50 being closed closes a circuity from pole 8 of battery l) through winding 53 of relay P, contact 52 5() of relay P, and plug-jack contact 1S 1() ot' line B to ground. Current from battery D flowing through this circuit keeps relay P energized until the plug F disconnected from the jack C, independcut ot whether a circuit of battery D is closed through winding 45 o relay P or not. N ow the parties at substations A and B are `connected tor conversation with each other. the talking circuit being continuous through contacts 2:1 32 and 4:1 l2 of relays L and N, respectiyely. all ot' the relays except relay H being now energized. When the conversation is completed and the party at substation hangs his receiver upon the switch-hook he opens the circuit ot' his metallic line at his substation and thei'cby stops the tlow ot current through supervisory relay K. thus allowing relay K to release its armature and close contact it 3o. Contact 29 30 being closed closes a circuit from pole 8 of battery l) through contact 30 answering supervisory lamp L) and plug'-y jack contact; 18 l0 of line C to ground. Current from battery D tlowing through this circuit lights the supervisory lamp which indicates to the operai or that the party at substation has tiuished with the use ot' his line. When the party at. substation l hangs his receiver upon the switch-hook he opens the circuit of his metallic line at his substation and thereby stops the flow of current through winding 15 of relay l and winding il of the calling siuiervisoiwv rela); N. thus allowing relay N to release its armatures and thereby open c ontact il i2 and close contacts 0 41 and 3S 39. Contact 38 39 being closed closes a circuit from pole 8 of battery D through calling supervisory lamp 3T, contact 38 39 of relay N, and plug-jack Contact 18 lof line B to ground. Current from battery l) flowing through this circuit lights the supervisory lamp 37. which indicates to the operator that the party at substation B has finished with the use of his line. The operator now withdraws the connecting plugs E and F from their respective spring jacks C C, thereby opening the circuits of lamps 28 and 3T and extinguishing their signals. This tlisconnection of the lines also opens the circuits through the winding of relay L and through the winding 53 of relay l). therelrv permitting the armatures of these relays to release and take their normal positions. .tu making this disconnection the operator also opens the circuits through windings 19 and 20 of relay H, thereby stopping the flow of current through these windings 19 and 2b. Now all of the circuits and apparatus are in their normal position and condition, ready for other connections to be made for conversation between the lines of the system.

Ve do not Wish to limit this invention to all of the particular details, or to the particular pieces 'of apparatus', herein shown. as various modifications may be made there- 'in Without departing from the scope of the appended claims Vhat We claim as our invention is:

1. The combination in a telephone system having lines, of a connecting circuit for the,

lines, a source of ringing current, a ringing relay associated with the connecting cir-l cuit for applying the source of ringing current to a me when connection 1s made therewith, a supervisory signal, a supervisory relay having switching mechanism controlling 4the circuits of the sourcey of ringing current and the said. supervisoryy signal, an interrupter controlling a circuit of the supervisory. relay whereby the latter causes peri- 1c ringing and a periodic operation of the sald supervisor signal when connection is made with. a ca led line, the said interrupter being under control of the ringing relay, a locking relay adapted to be operated when the line with which connection is made is taken for use, and switching mechanism under control of the locking relay whereby the latter controls the circuits of the source of ringing current, of the interrupter, of the supervisory relay, and its own circuit, when the line-is taken for use while connection is made therewith, whereby said locking relay is locked in operated position until connection is disestablished with the line. The combination with a telephone system having lines, of a connecting circuit for the lines, a source of ringing current, a ringing relay, a supervisory relay, and a locking relay, associated with the connecting circuit and each havingswitching mechanlsm controlling the circuit of the source yof ringing current, and an interrupter controlling a circuit of the supervisory relay whereby periodic ringing is produced when connection is made with a called line, the said ringing relay applying ringing current to the called line when connection is made therewith, and the said locking relay preventingthe ringing current from bein after the same is taken for use while connection is made therewith.

3. .In a telephone system having lines, a connecting circuit for the lines, said connecting circuit having a talking strand therethrough, said talking strand having a section thereof disconnected therefrom, a source of calling current normally connected with said section of the talking strand, a relay for connecting said section with a line when connection is made therewith, a second relay controlling the connection of said section with said talking strand, and an interrupter controlling Said second relay whereby the source of calling current is periodically disconnected from said section when connection is made with a called line, to give periodic signaling over the line.

4. The combination with a telephone system having lines, of a connecting circuit therefor, said connecting circuit having a talking strand therethrough, a source of calling current normally connected directly with a section of said talking strand, a relay for continuing the circuit of said calling Vtem having lines,

applied to the line' source l. means whereby said ringing over a line when connection is made therewith, and interrupter means apart from the circuit of the said source of calling current fer periodically controlling the connection of lsaid calling source with said section of the talking strand, substantially as described.

5. The combination with a telephone sysof a connecting circuit therefor, said connecting circuit having a talking strand therethrough, said talking strand having a break therein, a source of calling current normally connected directly with a section of said talking strand, means` apart from the circuit of the said source ol calling current for periodically controlling the connection of said source of calling current with said section of the talking strand` and means for permanently disconnecting' said source of calling current from said talking strand and permanently establishing the continuity of said talking strand when the called line is taken for use while connection is made therewith.

6. In a telephone system having lilies. a connecting circuit for the lines, said connecting circuit having a talking strand therethrough, a break in said talking strand,- a source of wave form ringing current normally connected directly with a section of said talking strand by non-conductive connections, and means apart from the ringing circuit for disconnecting said source of calling current from said talking strand and establishing the continuity of said talking strand when the called line is taken for use while connection is made therewith.

7. The combination in a telephone system having lines, of a connecting circuit for the lines, said connecting circuit having a talking strand therethrough, said talking strand having a break therein, a source of calling current normally connected directly with a portion of said talking strand, means apart from the circuit of the said source of calling current for causing periodic signaling from Said source of calling current over a called line when connection is made therewith, and means for disconnecting said source of calling current from said talking strand and establishing the continuity of said talking strand when the called line is taken for use while connection is made therewith.

8. The combination with a telephone system having lines, of a connecting circuit for the lines, said connecting circuit having a metallic talking circuit therethrough and a third strand, a source of ringing current normally connected with a portion of the said metallic talking circuit, a ringing relay for applying ringing current over a called line when connection is made therewith, said ringing relay being connected with said third strand and being operated when connection is made with a line, an interrupter, relay controls imacat the circuit of said interrupter, a supervisory relay controlling the circuit of said source of ringing current and a portion ot the said metallic talking circuit, a supervisory signal underontrol of said supervisory relay, means whereby the said interrupter controls a circuit of the said supervisory relay whereby the latter causes periodic ringing over a called line when connection is madetherewith, and simultaneous periodic operation of said supervisory signal, a locking relay controlling aA circuitI of its own, the circuit ot the said source of ringing current, the circuit of the said interrupter, and 'the said circuit of thesupervisory relay, said supervisory relay and said locking relay haring respective windings which serve as impedances for the respective limbs of said talking circuit and whereby the said relays are energized when the line with which connection is made is taken for use, the said supervisory relay then disconnecting a portion of the ringing circuit from the said talking circuit and establishing the continuity of the talking circuit, and also rendering the said supervisory signal inoperative, the said locking relay then rendering the said source of ringing current and the said interrupter inoperative, provided they are not operated through other similar connecting circuits, said locking relay keeping itself in operated position until connection is disestablished with the line, and said supervisory relay becoming dencrgized upon the discontinuance of the use of the line with which connection is made, whereby the supervisory signal is operated.

9. ln a telephone system having lines, a connecting Acircuit for the lines, said convnecting circuit havingr a talking strand therethrough, a source of calling current norinaily connected directly with at least a portion of said talking strand, means apart from the circuitof the said source of caliing'current, for producing periodic ringing over said talking strand and a line when connection is made therewith, and a locking relay opening the circuit of the said source of calling current when the line is taken for use while connection is made therewith, said locking relay then closing a circuit of its own whereby it is heldin operated posit-ion until connection is disestablished with the line.

10. In a telephone system having lines, a connecting circuit for the lines` said connecting circuit having a talking strand therethrough, said talking strand being normally divided into sections, a source of -calling current normally connected with a section of said talking strand, a relay for applying calling current to a line when connection is made therewith, means for proiucing periodic ringing over said talking atrand and the kine when connection is made' is held in operated position until connection is dis-established with the line.

1ll In a telephone System having lines,

the combination of a connecting circuit forthe lines, said connecting circuit terminating in a pair of connecting plugs, an operators telephone set normally disconnected from the connecting circuit, said telephone set having a transmitter the battery circuit of which is normally open, and a differential relay controliing the connection of the operator-s set with the connecting circuit and the battery circuit through the operators transmitter, said relay having a pair of windings connected with the respective connecting plugs, whereby the connection of either one of the said connecting plugs with a line connects the operators telephone .setwith the connecting circuit for conversational purposes, and whereby the connection of both of the said connecting plugs with the lines causes the operator`s telephone set to be disconnected from the connecting circuit and the operators transmitter battery circuit to be opened.

12. telephone exchange system including telephone lines extending to an exchar'ige` connecting apparatus for uniting. lines in conversation, operators telephonie apparatus including a telephonie transmitter, a source of current for supplying said transmitter with operating current, and

mechanism governed by the connecting ap- 'zoV 14. A telephone exchange system including telephone lines extending to an exchange, connecting apparatus for uniting lines in conversation, operators telephone apparatus, and electro-magnetic mechanism for automatically controllingr the association of.

said apparatus with said connecting apparatus and for controlling the application of current to the operators transmitter by way of the connecting apparatus.

15.'A telephone exchange system including telephone lines extending to an exchange,

connecting' apparatus for unit-ing' lines in ctnwersalion, operators tele '1 including' a teler' of current for supplying' sali with operating current,` and nu' erned by the connecting' appara trollingr the application ot' current erators transmitter' by Way of the inn' apparatus.

1G. A telephone exchange system harina' a common battery and including telephone lines extending to an exchange, connecting apparatus for uniting' lines in conversation, operators telephone apparatus in:- :ding a telephone transmitter in circuit connection with the common battery, a source of current for supplying' said transmitter with operating current, and electro-magnetic :riechanisin lgoverned by the connecting apparatus for controlling' the application of current to the operators transmitter.

17. A telephone exchange system including' telephone lines extending to an exchange, operators telephone apparatus, and electromagnetic mechanism whose operation is effectedwhen said connecting apparatus is united With a calling line for the purpose of associating' the operators telephone outfit. with the callingA line and supplying' the operators transmitter with operatingcurrent, and which electro-magnetic mechanism is released Iwhen the connecting apparatus is united with a called line, thereby to exclude the operators telephone set from circuit.

ismit-ter .f.= the opconnect- 18. A telephone exchange system including' telephone lines extendingr to an exchange, operators telephone apparatus, and electromagnetic mechanism for including,r the operators telephone set in circuit and supplying the transmit-ter thereof with operating current, said mechanism including' an electro magnet haring` differentially Wound coils, the circuit through one of lWhich bein,"T controlled by the connecting apparatus and apparatus associated With the calling line and the circuitthrough the other ofavliich beine; controlled by the connecting apparatus and apparatus associated with the called line.

19. A telephone exchange system including telephone lines extending' to an exchange,

q l operators telephone apparatus, and electromagnetic mechanism for including the operators telephone set in circuit and supplying' the transmitter thereof Withl operating current, said mechanism including" an electro-magnet having' differentially Wound coils, the answerinaf'end of the connecting' apparatus entering' into the control of one I' coil and the connecting end of the connecting apparatus entering into the control of the other coil.

Q0. A telephone exchange system including telephone lines extending' to an exchange, operators telephone apparatus, and electrosaid ineciroperators tel map'rn'ltic mechanism for supplyinf" i oratore tr filth ogo'" havin;`J` diiierentufir 'si' cc" cuit through one oi' which teine' by the connectii raratuand params associated with il? wilma' liuc and the circuit through thel other of which being' controlled by the ccnnectine apparatus' and apparatus associated with the called line.

Qi. A telephone exchange system including' telephone lines extending' to an c 'hanx'e,

eohone apparatus, and electroi'najgnetic mechanism for suppl; l j the transmitter thereof 'with og'feratine' current. said mechanism including' an ele' havin-r ditllerential-ly wound ci swerii end oi the connecting' apparatus cntering into the control of one coil and the connecting end of the connecting apparatus entering into the control of the other coil.

A telephone system including telephone linw extending' to an exchange t'roin sub-stations, jack switches Yin association with the telephone lilies, connecting plugs for engagement with said switches. a source ot signaling current-tor operating' the signal receivers a. called sub-stations. a relay pci'- niitting the separation of each connecting' plugtrom the source ot ruling current, switching mechanism gnu'cincd by the associate connecting plug for operating said relay to connect the plug' with the source of ringing current, and thereby to traiisinit the ringing' current to the called station, a sccond relay serving', when inertgto permit ot the connection of the signaling' current with the connecting plug by the switching' mecha# nism controlled by the first aforesaid relay and adapted to hare circuit closed therethrough by the switching; mechanism at the called sub-station when the signal is yresponded to tliereat. :in/l thereby to remore the signaling currentV trom the called line, athird relay haringA z-zuitchinar mechanism serving, when unattracted, to dissociate the signaling' current from the calling line and to permit of the passage of such current to the called line, and an interruptor included in circuit with said last relay, whereby naling currentis intermittently applied to the called line, the second relay, when encrp'ized, opening said interrupter circuit.

ccnl rollt'4 93. A telephone system including telephone'lines extending to an exchange from sub-stations, jack switches inv association with the telephone lines, connectingr plugs for engagement with said switches. aY source ot signaling current for operating the signal receivers at called sub-stations` a relayv `pcr mitting the separation of each connecting plug from the source vof signaling current, switching mechanism `governed by the associate connecting' plug for operating'said relay to connect'the plug' With the source of rtv-magnet llt) ringing current. and thereby te transmit the ringing current to the called station. a' second relay Serving. when inert. to permit ol' the connection of the signaling current ivith the connecting plug' by the switching mechanism controlled b v the first aforesaid relay and adapted to have circuit closed therethrough bv the switching mechanism at the called sub-station when the .signal is rcsponded to thereat. and thereby to remove the signaling current t'rcm the called line.v a third relay having switching mechanism serving. when unattracted. to dis-ociate the signaling current "from the calling 'line and to permit of the passage ot' such current to the called line. an interrupter included in circuit vvith said last relay. vvherehy -signaling current is intermittently applied to the called line. the second relay. when energized. opening said interrupter circuit. and a locl'- ing circuit for the second relay established vvhen it is energized and breakable at the exchange.

Q4. .X telephone system including telephone lines extending to an exchange from sub-stations. jack switches in association with the telephone lines, connecting plugs for engagement vvith said switches. a source ot signaling current for operating the signal receivers at called sub-stations. a relay serving` when inert. to permit of the connection of the signaling current with the connecting plug and adapted to have circuit closed therethrough by the switching mechanism at the called sub-station when the signal is respondedI to thereat. and thereby to remove the signaling current from the called line. a second relay having switching mechanism serving, when unattracted. to dissociate the signaling current from the calling' line to permit of the passage of such current to the called line` and an interrupter included in circuit with said second relay. whereby signaling current is intermittently applied to the called line. the first relay. vvhen energizcd. opening said interruptor circuit.

25. A telephone system including telephone lines extending tt, an exchange from sub-stations. jack switches in association with the telephone lines, connecting plugs for engagement with said switches. a source of signaling current for operating the signal receivers at called sub-stations, a relay serving, when inert, to permit of the connection of the signaling current with the connecting plug and adapted to have circuit closed therethrough by the switching mechanism at the called sub-station When the signal is responded to t-hereat, and thereby to remove the signaling current from the called line, a second 'relay having switching mechanism serving, when unattracted, to dissociate the signaling current from the calling line and to permit of the passage of such current to the called line, an interrupter included in circuit vvith said second relay. whereby signaling current is intermittentlyv applied to the called line. the first relay. vvhen energized, opening' said interruptcr circuit. and a lecking circuit for the said relay established when it is energized and hreakable at the exchange. j

Q6. A telephone exchange system including telephone lilies extending from Substations to an exchange. a cord circuit uniting lines in conversation, a ringing currentI generator. an electro-magnet for each cord circuit serving. when inert, to include the source of ringing current in circuit relation ivith the signal bell atthe called `station and having tvvo circuits, one establishable at the called station when the party there responds and the other establishable by said electromagnet,` said electro-magnet, when energized. serving to remove the calling gener-a1 tor from circuit relation with the called line.

2T. A telephone exchange system including telephone lines extending from sub-stations to an exchange. a cord circuit for uniting lilies in conversation, a ringing current generator. an electro-magnet for each cord circuit serving. when inert. to include the source of ringing current in circuit relation with the signal bell at the called station and having tvvo circuits. one establishable at the called station when the party there responds. and the other establishable by said electromagnet, said electro-magnet, when energized, serving to remove the calling generator from circuit relation with the' called line, the circuits for said electro-magnet including switching mechanism governed by an associate connecting plug.

28. A telephone exchange system including telephone lines extending from substations t-o an exchange, a cord circuit for uniting lines in conversation, a ringing current generator` an electro-magnet for Ieach cord circuit serving, when inert, to include the source of ringing current in circuit relation with the signal bell at the called station and having tivo circuits. one establishable at the called station when the party there responds, and the other establishable "by said electro-magnet, said electro-magnet, when energized, serving to remove the calling generator from circuit relation With the called line, the circuit that is establishable by the electro-'magnet being governed by the connecting plug, so that it may be opened when the parties are through, again to make Said electro-magnet inert to enable the generator controlled thereby again to be included in circuit relation with a called line.

29. A telephone exchange system including telephone lines extending from substations to an exchange. a cord circuit for uniting lines in conversation, a ringing current generator, an electro-magnet for each cord circuit serving, when inert, to include the source of ringing current in circuit relation with the signal bell at the called station and havmg two circuits, one establishable at the called station when the party there responds, and the other establishable by said electromagnet, said electro-magnet, when energized, serving to remove the calling generator from circuit relation with the called line, the circuits for said electro-magnet includlng switching .mechanism 'governed by an associate connecting plug, the circuit that is establishable by the electro-magnet being governed by the connecting plug, so that it may be' opened when the parties are through again to make said electro-magnet inert to enable the generator controlled thereby again to be included in circuit relation with a called line.

30. A telephone exchange system including telephone lines extending from sub-stations to an exchange, a link connector uniting lines in conversation, a ringing current generator, an electro-magnet for each link connector serving, when inert, to include the Vsource of ringing current in circuit relation with the signal bell at the called station and having two circuits, one establishable at the called station when the party there responds 4and the other establishable by said electromagnet, said electro-magnet, when energized, serving to remove the calling generator from circuit relation with the called line. y

31. A telephone exchange system including telephone lines extending from sub-stations to an exchange, a link connector for uniting lines in conversation, a ringing current generator, an electro-magnet for each link connector serving, when inert, to include the source of ringing current in circuit relation with the signal bell at the called .station and having two circuits, one establishable at the called station when the party there responds, and the other establishable by said electro-magnet, said electro-magnet, when energized, serving to remove the calling generator from'circuit relation with the called line. the circuits for said electro-magnet including switching mechanism governed by au associate connecting terminal.

32. A telephone exchange system including telephone lines extending from sub-stations to an exchange, a link connector for uniting lilies in conversation, a ringing current generator, an electro-magnet for each link connector serving, when inert, to include the source of ringing current in circuit relation with the signal'bell at the called station and having two circuits, one establishable at the called station when the -party there responds, and the other establishable by said electro-magnet, said electromagnet, when energized, serving to lremove the calling generator from circuit relation with the called line, the circuit that is establishable by the electro-magnet being governed by the connecting terminal, so that it may be opened when the parties are through, again to make said electro-magnet inert'to enable the generator controlled thereby again to be included in circuit 'relation with a called line.

33. A telephone exchange system including telephone lines extending from sub-stations to an exchange, a link connector for uniting lines in conversation, a ringing current generator, an electro-magnet for each link connector serving, when inert, to include the source of ringing current in circuit relation With the signal bell at the called station and having two circuits, one establishable at the called station when' the party there responds, and the other establishable by Said electro-magnet, said electro-magnet, When energized, serving to remove the calling gcnerator from circuit relation with the called line, the circuits for said electro-magnet including switching mechanism governed by an associate connecting terminal, the circuit that is establishable by the electro-magnet being governed by the connecting terminal, so'that it may be opened when the parties are through again to' make said electromagnet'inert to enable the generator controlled thereby again to be included in cir- .Cuit relation with a called line.

34. A telephone exchange system including telephone lines extending from substations to an exchange, link circuits for uniting lines in conversation, a source of signaling current, a switch normally connecting said source of signaling current with the link circuits, and mechanism for operating said switch to remove the generator from circuit and itself operated by apparatus at the called substation..`

As inventors of the foregoing We hercunto Subscribe our names in the presence ot two subscribing Witnesses, this l-lth daf/of September, 1908.

ELMEH R. CORW'IN. CHARLES A.. BALS. `Witnesses FREDERICK R. PARKER, H. Hor Coon.

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