US930516A - Telephone system. - Google Patents

Description

H. G. WEBSTER. TELEPHONE SYSTEM.

APPLICATION FILED DEC. 4, 1905.

E "I I I I IHI Patented Aug. 10, 1909.

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nrrnn STATES PATENT oFFrc HARRY e. WEBSTER, or criieAeo, ILLINois, ssIeNoR To MILO e. KELLOGG, or CHICAGO,

, ILLINOIS.

TELEPHONE SYSTEM.

Specification or Letters Patent.

Patented Aug. 10, 1909.

Application filed December 4, 1905. Serial No. 290,163.

To all whom it may concern:

Be it known that I, HARRY G. WEBSTER, a citizen of the United States, and resident of Chicago, county of Cook, and State of Illinois, have invented. new and useful Im; provements in Telephone Systems, of which the following is a specification.

The present invention relates to telephone systems generally, and more particularly to the arrangement of circuits and apparatus by which the subscriber and operator may signal each other, and by which the oper ator may be informed of the operative condition of a connectedtelephone line;

The object of this invention is to provide a novel organization of circuits and apparatus for accomplishing these functions.

In accordance with my invention, the usual link-circuit, for inter c'onnecting" the telephone lines leading to the central ofiice', is employed in association with a novel ar-' rangement of circuit connections by which the connection of the linkc'ircuit to a tele phone line closes a circuit local to the Gen tral office and establishes a path in shunt to a portion of said circuit which is under the control of the subscribers switch-hook; The closing of the local circuit, while the shunt remains open, causes the display of an associated supervisory signal and pre-i vents the energization of the call signal magnet associated with the connected tele phone line, while the closing of the shunt path causes the eila'cement of the super visory signal. I

The invention also comprises a novel arrangement of circuits and connections by which the call-signal is placed beyond its substation control.

The character of the invention will be more fully understood upon reference to-the' following detailed description taken in con: nection with the accompanying drawing, and the scope of the invention will be indicated in the appended claims.

In the said drawing, I have illustrated diagrammatically a telephone system embody ing the features of the present invention.

In said drawing, substations A; and B are shown connected to a central ofiice O. The equipment'at substation A, which may be of any referred ty e,is here shown embodying a ca l-bell 1 inc uded in series with a condenser 2 between the limbs 3 4 of the telephone line,- by which the substation is con nected to the central office. The circuit through the call-bell 1 is normally closed by the switch-hook 5, so that incoming ringing current will find a path through the call-bell and the condenser. Included in a normally broken circuit between the limbs 3 and 4 of the telephone line, is the transmitter 6 and the primary winding of an induction coil 7. When the receiver 8 is removed from its hook 5, the circuit through the call-bell 1 is broken, and that through the transmitter and the primary winding of the induction coil is completed. The receiver is included in circuit with the secondary winding of the induction coil; At the central oflice, the limbs 3 and 4 of the telephone line terminate in the sleeves 9 and the spring contacts 10 of the usual multiple jacks. The limb 3 also normally in cludes in circuit a portion 11 of the winding of the callsigiial'-efi'acing electromagnet 12 which, as here shown, cooperates with an armature 13 to break the circuit including the call-signalmagnet 14, and thereby cut ofi said magnet from its associated telephone line. Obviously, instead of cutting off the call-signal from the control of the substation, other control-eliminating means may be employed equally well without departing from the spirit of the present invention. The attraction of the armature 13 breaks the branch-conductor 15 which extends from the limb 4 of the telephone line, through the winding of the call-signal-magnet 1 1, to the live pole of the grounded battery B. Normally, the armature 13 remains in engagement with its contact 16 to maintain the branch 15 unbroken. An armature 17, shown at the opposite end of the electromagnet 12, is permanently connected at 17 to the limb 3 of the telephone line and is adapted normally to engage the grounded contact 18 and to be drawn, by the energization of the electroma net, against the contact 19 which is direcfiy connected at 20 'to the limb 3 of the telephone line. With the armature 17 engaging the contact 19, it will be noted that the portion 1 1 of the winding of the electromagnet 12 is short circuited, and the limb 3 is freed from resistance or impedance. The call-signal, which is preferably an electric lamp 20, is included in a grounded branch 21, controlled by the armatiire 220i the call-signal-inagnet 14. Normally, this branch is broken, but is closed when'the electro'riiagnet 14 is energized.

The circuits and apparatus associated with 1 contact 63 which is directly connected by substation B are substantially the same as those described in connection with substation A and are designated by corresponding primed characters.

Referring to the means at the central ofiice for connecting difierent subscribers for conversation, 23 represents the answering plug whose tip and sleeve are connected respectively to the strands 24 and 25 of the cord or link-circuit. Thesestrands are provided with the usualcondensers 26 27 and terminate at their opposite ends in the tip and sleeve, respective y, of the calling-plug 28. A supervisory signal-controlling elec tromagnet 29, associated withthe answeringplug 23, is connected by means of the conductor 30 in bridge of the strands 24 and 25, and a second supervisory signal-controlling electromagnet 31 associated with the callingplug 28, is bridged, by a conductor 32, between the said strands on the calling-plug side of the condensers 2627. The conductors 30 and 32 are connected by a conductor 33, which includes, in circuit, impedances 34 and 35. The conductor 33 is connected at a point between the impedances 34 and 35 with the live pole of the battery B by means of a conductor 36 and a portion of the branch-conductor 15. The supervisory signals 3839, which are preferably electric lamps, are included in grounded branches 40 and 41, under the control of the armatures 42 and 43, associated with the electromagnets 29 and 31 respectively. These branches are normally open, but may be individually closed upon the energization of the associated magnet. A listening-key 4445 is adapted to connect the answering-plug contacts, by way of the strands 2425, to a bridged conductor 46, including in circuit a condenser 47, the primary winding of an induction coil 48 and the operators receiver 49. The 0 erators transmitter 50 is included in a ocal circuit with the battery B and the secondary winding of the induction coil 48. A ringing-key 51-52 is arranged to break the metallic circuit of the strands 2425 at the back contacts 5354 and to connect the tip of the plug 28, by means of the front contact 55, to a grounded branch including the generator 56, and to connect the sleeve of the plug 28 to the live pole of the battery B by way of the front contact 57 and the branch conductor 58. The latter branch is provided with an impedance 59 in circuit. The back contact 53, associated with the movable contact 51 of the ringingkey, is connected by a conductor 60 with an armature 61 associated with the electromagnet 31. Normally, this armature engages a -fixed contact 62 which is directly connected through a tertiary winding of the inductioncoil 48 to ground. magnet 31, the armature 61 engages a-fixed When attracted by the the conductor 64 to the strand 24.

In the operation of the system, assuming that the subscriber at substation A desires to converse with the subscriber at substation B, he removes his receiveriroin itshook,t11c1eby completing a circuit, which will cause the energization of the.callsignal-magnet l4 and the consequent display 01' the call-signal 20. This circuit may be traced from the live pole of the battery B, through the branch 15 including armature 13 and contact 16 of the control-magnet 12, to the limb 4 of the telephone line, thence to the substation through the switch-hook 5, primary winding of the induction coil 7, transmitter 6, through limb 3 of the telephone line, the armature 17 and contact 18 of the control-magnet 12, to ground. This will suiiiciently energize the call signal magnet 14 to draw over its armature 22 to close branch 21, which includes the call-signal 20 in circuit, and thereby cause the display of said signal. Upon observing the display of this signal, the operator will insert the answering-plug 23 into one of the jacks associated with the telephone line 34 and press the listening-key 4445 to close a circuit between the substation and her telephone-set in order to determine the wishes of the calling party. The insertion of the plug 23 into the jack will close a circuit local to the exchange through the signal-controh ling electromagnets 12 and 29, as follows: from the live pole of the battery B, through a portion of the conductor 15, the conductor 36, branch 33 including the impedance 34, branch 30 including the winding of the electromagnet 29, thence through the strand. 25 of the link-circuit to the sleeve 01' the answering-plug 23, thence through the sleeve 9 of the jack, portion of the limb 3 of the telephone line, the portion 11 of the winding of the controhmagnet 12, and the armature 17 and contact 18 of said magnet, to ground. This will sufliciently energize the electromagnet 12 to draw the armature 13 away from contact 16 and thus interrupt the circuit through the winding of the call-signalmagnet 14 and thereby remove the control of said magnet from the operator at substation A. The same energization of the eleetromagnet 12 will attract the armature 17 against the contact 19, thus short-circuiting the portion 11 oi the winding of said electromagnet and completing a circuit from the point 20, through the contact 19, armature 17, to the limb 3, thence through the other portion of the winding 01' the electromagnet 12, to ground. This second circuit will also sufficiently energize the eleetromagnet 12 to maintain its armatures 13 and 17 in their attracted positions.

It will be observed that when the operator has inserted the plug 23 into one of the jacks, and the electromagnet 12 has been energized to cut or? the control of the call signal, a second path, through the substation and in shunt to a portion of the local circuit at the central oflice, will exist. This shunt path extends from the point in the conductor 30, through a portion of said conductor, a portion of the strand 24, to the tip of the plug 23, thence through the spring contactlO of the jack, limb 4 of the telephone line, through the substation, back through limb3 of the telephone line, to its point of connection 17 a with the branch leading to the armature 17. The portion of the local circuit shunted by this substation path extends from the point 30 in the conductor, through said conductor including the winding of the electromagnet 29, to the strand 25, through said strand to the tip of the lug 23, thence through the jack-sleeve 9, irnb 3 to the point 20 thence again to the limb 3 at the point 17 by Way of the contact 1'9 and armature 17. When the central oflice circuit alone is closed, the current flowing in it is sufficient to energize the electromagnet 29 sufliciently to attract the armature 42 to close the grounded branch 40 and thereby cause the display of the signal 38. If, however, while the central oflice circuit remains closed, the substation shunt be closed also, as by the removal of receiver 8 from its hook, enough current will be shunted from the central oflice circuit to deenergize the winding of the electromagnet 29 sufiic'iently to allow its armature 42 to be drawn against its back stop and the supervisory signal 38 thereby to be e'iaced.

Upon closing the listening-key 44L45, the branch 46 is included in circuit with the transmitter at substation A and the wishes of the party at said substation learned by the operator through the instrumentality of her telephone-set, comprising the transmitter 50 and receiver 49. Having learned that the calling party wishes to converse with the subscriber at substation B, theoperator first tests the line of the latter substation by pl acing the tip of the plug 28- against the sleeve 9 of one of the jacks associated with said substation line. If the latter line is busy, a potential will exist upon the sleeve 9 which will cause a momentary flow of current through the strand 2%, the movable con tact 51 of the ringing-key 51 52, the back contact 53, the branch 60, armature 61, contact 62 and the tertiary windiiig ofthe induction coil 48, to ground. This will cause a click in the operators receiver 49, thus indicating to her that the line is busy.

If the line is found to be idle, the operator inserts the plug 28 into one of the jacks associated with the line 3 i and closes the ringing-key 51 52. Prior to the closing of the ringingdrey, a local circuit, corresponding to the local circuit through the windings of the electromagnets 12 and 29, at the all-- swefring end of the link-circuit, is completed through the windings oi' the electromagnets net 12, the armature 17 and contact 18, to

ground. This, as previously explained, will interrupt the branch 15 including the winding of the call-signal-magnet 14 associated with the telephone line 34 and at the same time short circuit the portion 11 of the winding of the electromagnet 12 and com plete a circuit through the other portion of said winding, to ground, thus maintaining the armatures 13 and 17 in their attracted positions. Upon closing the ringing-key 5152, this local circuit is broken at the contact 54, but a second circuit is completed from the live pole of the battery through a portion of theconductor 15, the branch 58 including the impedance 59, the contact 57 and themovable contact 52 of the listeningkey and the strand 25 to the sleeve of'the calling-plug 28 and thence, as before, through the winding of the electromagnet 12. By this circuit, the armatures 13 and 17 are maintained in their attracted positions,

while the ringing-key is held depressed. At i the same time, the movable contact 51 of the ringing-key connects the tip of the plug 28 through the generator 56 to ground, and a circuit is completed through the branch 4 of the telephone line, the switch-hook 5, callbell 1, condenser 2, branch 3 of the telephone line and the grounded portion of the winding of the cut-oft relay 12, to ground. Current is thus supplied to actuate the callbell 1 at substation B. As soon as the ringing-key 51-52 is released, the local circuit through the windings of the electromagnets 12 and 31 is completed again and, until the receiver at substation B is removed from its hook, the current flowing in said circuit is sufiicient to maintain the signal 39 displayed.

When the subscriber at substation B removes his receiver 8 from its hook in response to the call, he closes a path over the telephone line in shunt to a portion of the local T central ofli ce circuit including the windings of the magnets 12, and 31, previously traced. This shunt path shunts enough current from the said winding of the electromagnet 31 to cause the eil'acement of the signal 3 9. It is substantially the same as that traced in connection with substation A, but for clearness may be traced again as follows: from the point 32' in the branch 32, through a portion of said branch to the strand 24 of the linlr-circuit, thence through the branch 64, the contact 63, armature 61, which will remain at tracted by the lesser flow of current through the winding of the electromagnet 31 against its contact 63, the branch. 60, contact 53, movable contact 51, link-conductor 24, to the tip of the calling-plug 28, thence through the spring-contact 10 of the jack, limb 1, through the substation, back through limb 3 to the point of its connection 17 with the branch leading to the armature 17 of the electromagnet 12. With the subscribers so connected, conversation may be carried on between them over a metallic circuit including the limbs 34 and 34 of their telehone lines and the strands 24 and 25 of the ink-circuit, as usual; and during this conversation, both of the supervisory signals 38 and 39 will remain eiiaced. However, when either subscriber hangs up his receiver and thereby breaks his shunt to the electromagnet controlling the corres onding supervisory signal, said signal will be displayed; and when both signals 38 and 39 are displayed, the operator will then know that conversation is ended and may disconnect the subscribers.

During conversation, talking current is supplied to the telephone lines by a circuit from the live pole of the battery B, a portion of the conductor 15, the conductor 36, to its connection with the conductor 33, there dividing; a portion of the current passing through impedance 34, stand 24, to the tip of the plug 23, spring contact 10 of the jack, over the branches 4 and 3 of the telephone line including the induction coil and transmitter at substation A, and through the grounded portion of the winding of the electromagnet 12, to ground; and the other portion passing through the impedance 35, the stand 24, to the tip of the plug 28, thence through the spring contact 10 of the jack, the limbs 1 and 3 of the telephone line including the induction coil and transmitter at substation B, and through the grounded portion of the winding of the electromagnet 12, to ground. /i ith this arrangement, it will be seen that the impedance 34 balances the impedance due to the energized portion of the electromagnet 12, while the impedance 35 balances that due to the electromagnet 12 From what has been previously stated, it will also be apparent that these same impedances are common to the subscribers cirwits and the central o'llice local circuits which cooperate in the control of the supervisory signals 38 and 39. These impedances,

therefore, also assist in the shunting action by which the electromagnets 29 and 31 are denergized when the substation circuits are closed.

It will be understood that, in the practice of my invention, many changes may be made without departing from the spirit and scope of the same. For example, batteries B and B may be one and the same battery, instead of separate batteries as shown in the diagram. Furthermore, the substation equipment may be replaced by other forms of equipment, the signal lam as may be replaced by other types of signa s, and other modifications of the system employed. 1 therefore do not wish to be limited to the precise matter disclosed, but aim to cover, by the terms of the appended claims, all such alterations and modifications.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. A telephone system comprising a telephone line extending -from a substation to a central oflice, a line signal controlling relay, a supervisory relay, a resistance, means under the control of the operator for energizing said relays by closing a circuit including said relays and resistance, means for displaying a signal in response to the said energrzation of the supervisory relay, means under the control of the subscriber for shunting current from said supervisory relay by closing a path between one terminal of the winding of said signal controlling relay and a point intermediate of said supervisory relay and said resistance, whereby said signal is eflaced.

2. A telephone system comprising a telephone line extending from a substation to a central ofiice, a line signal controlling relay, a link-circuit adapted to make connection with said line, a supervisory relay and a source or" current associated with said linkcircuit, means operative upon the connection of said link-circuit to said line to energize said relays, means for displaying a signal in response to said energization of said supervisory relay, means under the control of the subscriber for eifacing said signal by shunting current from said supervisory relay by closing a path including only the resistance of said telephone line and the connected substation apparatus whereby said signal is efiaced.

3. A telephone system comprising a telephone line extending from a substation to a central office, a line signal controlling relay, a link-circuit adapted to make connection with said line, a supervisory relay, a resistance and a source of current associated with said link-circuit, means operative upon the connection of said link-circuit to said line to energize said relays, means for displaying a signal in response to the said energization of said supervisory relay, means under the control of the subscriber for shunting current from said supervisory relay by closing a path between one terminal of the winding of said signal controlling relay and a point intermediate of said supervisory relay and said resistance, whereby said signal is effaced.

4. A telephone system comprising a telephone line extending from a substation to a sealers 1 central ofiice, a line; signal controlling relay-,- a resistance, a supervisory-relay, a source current, means under the control of the ope erator for closing a circuitincludin'g', said source of current, said resistance and-said relays, means for displaying a-signal in response to the energization, of saidsupervisory relay resulting from theclosing; of said circuit, means under the control of the sub scriber for shunting current from said supervisory relay by closing a shunt path extending from a point intermediate of said resistance and supervisory relay out over said telephone line and back to another point in said circuit, whereby said signal is efiaced.

5. A telephone system comprisinga telephone line extending from a substation to a central office, a line signal controlling relay, a link-circuit adapted to make connection with said line, a supervisory relay, a source 01' current, a resistance, means operative upon the connection of said link-circuit to said line to close a circuit including a source of current, said resistance and said relays, means for displaying a signal in response to the energization of said supervisory relay resulting from the closing of said circuit, means under the control of the subscriber for shun ing current from said supervisory relay by closing a shunt path extending from a point intermediate of said resistance and supervisory relay out over said telephone line and back to another point in said circuit, whereby said signal is ei'faced;

6. A telephone line extending from a substation to a central office, a two-strand linkcircuit adapted to make connection with said line, an inductive device associated with said link-circuit for permitting the passage of voice currents and preventing the passage of signaling current, a source of current and a resistance normally associated with said links circuit, a signal-controlling electromagnet bridged between said link-circuit strands on the said telephone-line side of said inductive device, means operative upon the connection of said link-circuit to said telephone line to complete a circuit through said resistance, source of current and ,electromagnet winding, means for displaying a signal upon the energization of said electromagnet by a the closing of said circuit and means under the control of the subscriber for shunting current from said electromagnet whereby said signal is efiaced.

7. A telephone line extending from a sub: station to acentral ofiice, a-two-strand linkcircuit adapted to make connection with said.

resistance normally associated with said link circuit, a signal controlling electromagnet bridged between said link circuit ,strands'oii thsaid telephoneeline side of said inductive device, meansvv operative upon the connectioiioi' said link-circuit to said telephoneline to complete a circuit through said resistance, source of current and electromagnetwin din'g, means for displaying a sig nal upon the energization of said electromagnet by the closing of said circuit and means under the control of the subscriber for completing a path including the telephone line in shunt to said electromagnet winding whereby said signal is efi'aced.

8'. A telephone line extending from a substation to a central oflice, a two-strand linkcircuit adapted to make connection with said line, an inductivedevice associated with said link-circuit for permitting, the passage of voice currents and preventing the passage of signaling current, a source of current and a resistance normally associated with said link-circuit, a signal-controlling electromagnet bridged between said link-circuit strands on the said telephone-line side of said inductive device, means operative upon the connection oi saidlink-circuit. to said telephone line to energize said electromagnet, means for displaying a signal in response to said energization and means under the control of the subscriber for shunting current from said electromagnet whereby said signal is efiaced.

9. A telephone line extending from a substation to a central office, a two-strand link- 1 circuit adapted to make connection With said line, an inductive device associated with said link-circuit for permitting the passage of voice currents and preventing the passage of signaling current, a source of current and a resistance. normally associated. with said link-circuit, a signal-controlling electromagnet bridged between said link-circuit strands on the said telephone-line side of said inductivedevice, means operative upon the connection of said link-circuit to said telephone line to energize said electromagnet, means for displaying a signal in response to said energization and means under the control of the subscriber for completing a path including the telephone line in shunt to said electromagnet winding whereby said signal is efiaced.

10. A telephone line extending from a substation to a central ofi ice, a two-strand linkcircuit adapted to make connection with said i line, an lnductlve device associated with said We device, means operative upon the connectionof said link circui t to said telephone line to complete. a circuit through said re 1 sist-anee, source of current-and electromagnet winding, means for displaying a signal upon the energization of said electromagnet by the closing of said circuit, means under the control of the subscriber for shunting current from said electromagnet whereby said signal is effaced, a call signal magnet associated with said telephone line and means for deenergizing the call signal magnet upon the connection of said link-circuit to said telephone line.

1 1. A telephone line extending from a substation to a central ofiice, a two-strand linkcircuit adapted to make connection with said line, an inductive device associated with said link-circuit for permitting the passage of voice currents and preventing the passage of signaling current,- a source of current and a resistance normally associated with said linkcircuit, a signal-controlling electromagnet bridged between said link-circuit strands on the said telephone-line side of said inductive device, means operative upon the connection of said link-circuit to said telephone line to complete a circuit through said resistance, source of current and electromagnet winding, means for displaying a signal upon the energization of said electromagnet by the closing of said circuit, means under the control of the subscriber for shunting current from said electromagnet whereby said signal is eil aced, a call signal magnet associated with said telephone line and means for interrupting the current path through the call signal magnet upon the connection of said link-circuit to said telephone line.

12. A telephone line extending from a substation to a central oflice, a two-strand linkcircuit adapted to make connection with said line, an inductive device associated with said 1ink-circuit for permitting the passage of voice currents and preventing the passage of signaling current, a source of current and a resistance normally associated with said linkcircuit, a signal-controlling electromagnet having its terminals directly connected to said link-circuit strands on the said telephone-line side of said inductive device, means operative upon the connection of said link-circuit to said telephone line to energize said electroinagnet, means for displaying a signal in response to said energization, means under the control of the subscriber for causing the eiiacement of said signal, a call signal magnet associated with said telephone line and means for deenergizing the call signal magnet upon the connection of said link-circuit to said telephone line.

13. A telephone line extending from a substation to a central oflice, a two-strand linkcircuit adapted to make connection with said line, an inductive device associated with said .link-circuit for permitting the passage of voice currents and preventing the passage of slgnahng current, a source of current and a resistance normally associated with said 11nkcircuit, a signal-controlling electromagnet having its terminals directly connected to said link-circuit strands on the said telephone-line side of said inductive device,

means operative upon the connection of said link-circuit to said telephone line to energize said electromagnet, means for displaying a signal in response to said energization, means under the control of the subscriber for causing the etlacement of said signal, a call signal magnet associated with said telephone line and means for interrupting the current path through the call signal magnet upon the connection of said link-circuit to said telephone line.

14. A telephone line extending from a substation to a central oflice, a two-strand link-circuit adapted to make connection with said line, a source of current having one pole normally connected to one strand of said link-circuit, a single-winding signalcontrolling electromagnet having its terminals directly connected to the strands of said linlooircuit, means operative upon the connection of said link-circuit to said telephone line to energize said electromagnet, means for displaying a signal in response to said energization and means under the control of the subscriber for causing the cl'l'acement of said signal.

15. A telephone line extending from a substation to a central ollice, a two-strand link-circuit adapted to make connection with said line, a source of current having one pole normally connected to one strand. of said link-circuit, a resistance, a signalcontrolling electromagnet bridged between. the strands of said link-circuit, means operative upon the connection of said linkcircuit to said telephone line to complete a circuit through said resistance, source of current and eleetromagnet winding, means for displaying a signal upon the energization. of said magnet by the closing of said circuit and means under the control of the subscriber for shunting current from said elem tromagnet whereby said signal is eli'aced.

16. A telephone line extending from a substation to a central oflice, a two-strand link-circuit adapted to make conneotion with. said line, a source of current having one pole normally connected to one st and of said link-circuit, a resistance, a signal-(ontrolling electromagnet bridged between the strands of said link-circuit, means operative upon the connection of said link-circuit to said telephone line to complete a circuit through said resistance, source of current and electromagnet winding, means for displaying a signal upon the energization of said magnet by the closing of said circuit and means under the control of the subscriber for completing a path including the telephone line in shunt to said electromagnet winding whereby said signal is e'fl'aced.

1.7. A telephone line extending from a substation to a central oflice, a link-circuit adapted to make connection with said line, a source of current having one pole normally connected to one strand of said linl circuit, a single-winding signal-controlling electromagnet having its terminals directly and permanently in bridge of the strands of said link-circuit, means operative upon the connection of said link-circuit to said telephone line to energize said el-ectromagnet, means for displaying a signal in response to said energization and means under the control of the subscriber for causing the eiiacement of said signal.

18. A telephone line extending from a substation to a central office, a link-circuit adapted to make connection with said line, a source of current having one pole normally connected to one strand of said link-circuit, a resistance, a signal-controlling electromagnct in bridge of said link-circuit, means operative upon the connection of said linkcircuit to said telephone line to complete a circuit through said resistance, source of current and electromagnet winding, means for displaying a signal upon the energization of said magnet by the closing of said circuit and means under the control of the subscriber "for shunting current from said electromagnet whereby said signal is. ellaced.

19. A telephone system comprising a telephone line extending from a substation to a,

central office, a call signal associated with said line, electrically actuated means for removing the substation control of said call signal, a link-circuit, means operative upon the connection of said link-circuit to saidtelephone line for closing a circuit to cause the operation of said electrically actuated means, means operated upon the closure of said circuit to close a second circuitby which said electrically actuated means is maintained in its operated position, an electrically operated supervisory signal normally displayed upon the connection of said linkcircuit to said telephone line, and means under the control of the subscriber for shunting current from said signal to cause its eii'acement.

20. A telephone system comprising a telephone line extending from a substation to a central oflice, a call signal associated with said line, electrically actuated means for removing the substation control of said call signal, said means comprising a divided winding, a link-circuit, means operative upon the connection of said link-circuit to said telephone line for closing a circuit through one portion of said Winding to cause the operation of said electrically actuated means, means operated upon the closure of the circuit through the first portion of said winding to close a circuit through the second portion of said winding by which said electrically actuated'means is maintained in its operated position, an electrically operated supervisory signal normally displayed upon the connection of said link-circuit to said telephone line, and means under the control of the subscriber for shunting current from said signal to cause its eiiacement.

21. A telephone system comprising a telephone line extending from a substation to a central oflice, a call signal associated with said line, electrically actuated means for removing the substation control of said call signal, said means comprising a divided winding, a link-circuit, means operative upon the connection of said link-circuit to said telephone line for closing a circuit through one portion of said Winding to cause the operation of said electrically actuated means, means operated upon the closure of the circuit through the first portion of said winding to close a circuit through the second portion of said winding short circuiting said first portion by Which said electrically actuated means is maintained in its operated position, an electrically operated supervisory signal normally displayed upon the connect-ion of said link-circuit to said telephone line, and means under the control of the subscriber for shunting current from said signal to cause its eflacement.

2-2. A telephone system comprising a telephone line extending from a substation to a central oflice, a connection terminal therefor,

a call signal associated with said line, electrically actuated means for removing the substation control of said call signal, said means having a divided Winding, one portion of which is included permanently in circuit With one of the limbs of said telephone line, a link-circuit, means operative upon the connection of said link-circuit to said telephone line for closing-a circuit through that portion of said winding included in the limb of said telephone line, whereby said electrically actuated means is operated, means operated V upon the closure of said circuit to close a second circuit through the second portion of the Winding of said electrically actuated means, whereby said means is maintained in its operated position, an electrically operated supervisory signal normally displayed upon the connection of said link-circuit to said telephone line, and means under the control of the subscriber for shunting current from said signal to cause its etiacement.

23. A telephone system comprising a telephone line extendim from a substation to a central oflice, a call signal associated with said line, electrically actuated means for removing the substation control of said call signal, a link-circuit, means operative upon the connection of said link-circuit to said telephone line for closin a circuit to cause the operation of said e ectrically actuated means, means operated upon the closure of lOl) said circuit to close a second circuit by which said electrically actuated means is maintained in its operated position, means for simultaneously excluding said Winding from the talking circuit, an electrically 0perated supervisory signal normally displayed upon the connection of said link-circuit to said telephone line, and means under the control of the subscriber for shunting current from said signal to cause its efiacement.

24. A telephone system comprising a telephone line extending from a substation to a central ofiice, a call signal associated with said line, electrically actuated means for removing the substation control of said call signal, said means comprising a divided winding, a link-circuit, means operative upon the connection of said link-circuit to said telephone line for closing a circuit through one portion of said winding to cause the operation of said electrically actuated means, means operated upon the closure of the circuit through the first portion of said winding to close a circuit through the second portion of said winding by which said electrically actuated means is maintained in its operated position, means for simultaneously excluding said winding from the talking circuit, an electrically operated supervisory signal normally displayed upon the connection of said link-circuit to said telephone line, and means under the control of the subscriber for shunting current from said signal to cause its eliacement.

25. A telephone system comprising a telephone line extending from a substation to a central ofiice, a connection terminal therefor, a call signal associated with said line, electrically actuated means for removing the substation control of said call signal, said means having a divided winding, one portion of which is included permanently in circuit with one of the limbs of said telephone line, a link-circuit, means operative upon the connection of said link-circuit to said telephone line for closing a circuit through that )ortion of said winding included in the imb of said telephone line, whereby said electrically actuated means is o erated, means operated upon the closure or said circuit to close a second circuit through the second portion of the winding of said electrically actuated means, whereby said means is maintained in its operated position, means for simultaneously excluding said winding from the talking circuit, an electrically operated supervisory signal nor mally displayed u on the connection of said link-circuit to sai telephone line, and means under the control of the subscriber for shunting current from said signal to cause its effacement.

In witness whereof, I hereunto subscribe my name this 2nd day of Dec, A. D., 1905.

HARRY G. WEBSTER.

Vitnesses:

CAROLYN WEBER, O. H. DYsoN.

It is hereby certified that in Letters Patent No. 930,516, granted August 10, 1909, upon the application of Harry G. Webster, of Chicago, Illinois, for an improvement in Telephone Systems, errors appear in the printed specification requiring" correction, as follows: Page 3, line 122, thereference-numeral 12 should read 12, and

page 4, lines 34 and 42, the word stand should read strand; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofice.

Signed and sealed this 5th day of October, A. D. 1909.

[SEAL] I C. C. BILLINGS,

Acting Commissioner of Patents.

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