US897243A - Telephone system. - Google Patents

Description

No. 897,243; PATENTED AUG. 25, 1908.

H. G. WEBSTER. v TELEPHONE SYSTEM.

APPLICATION FILED NOV. 6', 1901.

UNITED STATES PATENT OFFICE.

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR TO MILO G. KELLOGG, OF CHICAGO,

' ILLINOIS.

TELEPHONE SYSTEM.

Patented Aug. 25, 1908.

Original application filed March 27, 1903, Serial No. 149,833. Divided and this application filed November 6, 1907. Serial No. 400,971.

To all "whom it may concern:

Be it known. that 1, HARRY G. Wicns'rmt, a citizen of the United States, residing at Chicage, in the county of Cook and State of Illinois, have invented new and useful Improvements in Telephone Systems, of which the following is a specification.

My invention relates to telephone systems and has for its object the provision of improved signaling apparatus.

This application, which is a division of my prior appllcation, Serial #149,833, filed March 27, 1903, is drawn to one species of the invention covered by said prior application.

In accordance with my invention, I provide at the central station a signal-controlling electromagnet which is under the joint control of the subscriber at the substation and the operator at the central ofiice. This electromagnet is preferably a relay magnet having a single energizing winding and operating to control a suitable signal, such as a lamp. In operation, the relay is energized to a limited extent to cause the display of its signal by the closing of the line circuit at the substation, thus calling the attention of the operator to the fact that the subscriberdesires a connection. It is further energized by the operator, preferably by the insertion o the connectim plug into the spring-jack or socket of the calling subscriber, to cause the effaccment of said signal. Preferabl the initial energization is produced by incfiiding a battery of low voltage in circuit with the electroma net winding and the further energization, r including a battery of higher voltage in circuit.

I have illustrated my invention in connection with a signal-controlling electromagnet in the form of a relay having a single armature ada ted to partake of an initial movement under the control of the subscriber, and to partake of a final movement under the control of the operator, the initial movement serving to actuate the signal for the connection, and the final movement serving to render the signal inert. These movements may also be utilized for erforming other functions, if desired. Wliile I have thus shown the magnet with a single armature adapted to partake of the two dlstinctive movements, it is apparent that this selective o eration may be procured in other ways, and do not therefore desire to limit myself to this par ticular feature of construction.

The specific character of the invention will be more fully understood upon reference to the following description, taken in connection with the accompanying drawing, and its novelty will be specifically pointed out in the appended claims.

Figure 1 of said drawing is a diagram illus trating my invention in connection with a two-wire metallic circuit telephone system; Fig. 2 is a detailed view, showing the armature of the relay in its intermediate position; and Fig. 3 is a similar view, showing the armature in its final position.

Throughout these views, like characters refer to like arts.

Referring rst to Fig. 1, the tele hone line extends from substation A in two ine limbs ab to the central station, Where the limbs terminate, res ectively, in the sleeve (1 and spring b of t e spring-jack or connection socket. A relay 0 1s provided, which is illustrated diagrammatically as a core and a winding rovided thereon, and this relay is connecter l in circuit between limb a and ground. A batter e of low voltage-say, ten volts-is inclu ed in circuit between the winding of the relay 0 and ground. The armature c of the rela is pivoted at c and carries an arm 0 whlch moves with the armature and is adapted electrically and 1nechanically to engage a contact-spring d. The spring (1 normally rests against a contact-spring d, which in turn normally rests against a third contact-spring d The con tact-spring d is connected to the limb b of" the telephone line, and the contact-spring d is connected through the branch 2 to ground. A second battery 6 of a voltage hi her than the batter esay, thirty vo tsis included in a branch extending from the pivotoint c of the armature c to ground. This ranch includes the si nal which is preferably an electric lamp. he atteries e and e, as shown, are arranged in series and with an intermediate common ground. v

The connecting apparatus at the central station comprises plugs h i, the plug h being provided with a ti h and a sleeve h, while the plug i is provi ed with a tip '5 and sleeve 11. The tips are connected by means of the tip-strands 7c-7c, separated by a condenser m, while the sleeves are connected by means of the sleeve-strands ZZ, similarly separated by condenser m. There are four re a s, 0, 0, p, p, associated with the strands Zcc and ll. A conductor 3, extending from the live pole of the battery 6, com letes a path through the winding of the re ay 0 to the strand l on the answering side of the condenser m, and a conductor i completes a circuit from the same pole of the battery through the winding of the relay 1), to the strand Z at the calling side of the condenser m. The relay 0 has its winding included in a grounded branch extending from the strand k at the answering side of the condenser m, and the winding of the relay .p is included in a similar grounded branch ex.- tending from the strand 7c at the calling side of the condenser m. The latter branch is adapted to be broken at the contact 5 when 'the lever n of the listening-in key is moved from its normal position. The relay 0 is provided with a contact-spring 0 which normally rests against an anvil o, and the relay 0 is provided with a similar contact-s ring 0 which is normally out of contact wit 1 the anvil 0 A signaling lam 0 is included in a grounded branch exten ing from the contact 0 the contact 0 is connected to the live pole of the battery 6 and the anvils 0 and 0 are conductively united. Likewise, the relay p is provided with a contact-spring 19 which normally rests against an anvil p and the relay p is provided with a contactspring p, which normally remains out of engagement with an anvil 29 A signaling lamp 6 is included in the grounded branch exten ing from the contact p is directly connected to t e live pole of the battery e, and the anvils p and p are electrically united. The levers nn of the listening-in key normally rest away from the anvils n n between which anvils the telephone-receiver s, the secondary winding 8 of the induction coil, and the condenser m are included in series. The primary 3 of the inductioncoil, the transmitter s and the battery 8 are included in a local circuit. The tertiary winding s is included in a path extending from the anvil n to the live side of the low voltage battery 6. The ringingkey t is adapted, when de ressed, to engage an anvil t to which one t is connected, the ot nected to ground.

At the substation A, I have illustrated usual substation apparatus, comprising a telephone-hook v normally resting against an anvil 10, which is connected to a bell v and condenser 12 to the limb b of the telehone line. im'b a of said telephone line. When the tele hone-receiver v is removed from the hoo '0. the latter engages anvil 12", which is pole being conthe contact 1p0 e of the generator The hook v is connected to the telephone line.

connected through the primary winding v" and transmitter 01 to the limb b of the Receiver '0 is included in a local circuit with the secondary winding o of the induction coil. The substation equipment, herein described, is merely illustrative and obviously any other desired equipment may be employed. without departing from the spirit of the present invention.

Assuming that a party at substation A desires to converse with a party atanother substation, he removes his telephone-receiver from its switch-hook and thus conductively unites the limbs a and b of the telephone line at the substation. A circuit, including low voltage battery e, is thereby closed. This circuit extends from the live pole of said batter through the winding of the relay c,-lim a, hook-switch v, anvil o primary winding 1), transmitter 12 limb b, contact-springs dd and branch 2 to the grounded side of the battery 6. This energizes the relay 0 sufiiciently to. bring the arm 0 and the spring-contact (Z into engage ment, thereby closing a circuit from the live side of' the battery 6 through the signal lampg, arm 0 springs 11, d, (1 and conductor 2, to the grounded side of the battery 6 This energization of the relay 0 is insuflicient to cause the arm 0 to press against the spring d hard enough to press the springs 11, d and d apart in the manner illustrated in Fig. 3, but, without separating these springs, brings thearm c and spring (1 into electrical enga ement in the manner shown in Fig. 2. The amp g, being thus lighted, conveys to the operator the signal for connection.

' It should be noted. that the flow of current from the battery 6 through the signal lamp g, does not interfere with the flow of current from the battery 6 through the winding of the relay 0, owing to the negligible resistance of the conductor 2, which is connected to the common ground.- At this time, relay 0 is energized, as before, over a circuit extending from the live pole of battery 6, through the winding of said relay, over line limb a, through the substation, back over line limb I), through contacts (1, d of relay 0, and through conductor 2 to thegrounded pole of the battery 6. Thereupon the operator inserts the plug it into the spring-jack belonging to the line of subscriber A, and thereby completes a second circuit through the winding of the relay 0 as follows: from the live pole of the battery e through conductor 3, windin of the relay 0, strand Z,

sleeve kg of the ng of the rela 0, through the battery 6 to the opposite po e of the battery 6 thus including a potential of forty volts in circuit since the batteries e and e are included in series by this connection.-

This circuit energizes the relay 0 sufficiently to draw the armature a into the position illustrated in Fig. 3 and thereb se arate the springs d, d and d*. This brea s the circuit of the signal lamp 9 and breaks the ground connection of the limb b of the telehone line. The operator now depresses er listening-in key and thus bridges her telephone in circuit and learns the wishes of the calling party. She then touches the tip 11' of the plug 71 to, the sleeve a of the spring-jack of the called subscriber and tests to ascertain whether or not the line is busy. If the line is busy, there will be a potential, due to both batteries e and e upon the sleeve a, by reason of the circuit through the rela 0, the strand 1, and the relay 0, by which t e latter is given its greatest energization. Since, when the listening-in key lever n is de ressed, the tip '1' will be directly connected t rough the tertiary winding 8 of the induction coil to the live pole of the battery e, itwill have a potential less than that of the sleeve a of the jack, and a momentar current will flow through the tertiary win ing and produce a click in the receiver 8, thus indicating the busy condition of the line. If, however, the line is not busy, the

plug '11 will be inserted in the spring-j ack and i the ringing key 23 depressed to send a calling current over the line of the called party.

The insertion of the plu 'L closes circuit through the relay 1) as fol ows: extending from the live pole of the battery e through the conductors 3 and 4, the winding of the relay p, the strand Z, sleeve 1?, sleeve (1' of the.

jack of the line of the called party, a portion of the limb a, the windin of the relay 0, the low voltage battery 6 0 the called partys line to ground and thence by the ground path to the grounded pole of the battery e of the calling partys line. This will sufficiently energlze the relay p to draw its contact 4 into engagement with ,the anvil 5 and c lose the grounded branch through tli e signal lamp 1)", causing it to light. This same circuit will energize the relay 0, associated with the line of the called party, sufficiently to separate the spring-contacts d, d and (1 associated therewith, and thereby remove the control of the associated signal 9 from said party. As soon as the called party responds and lifts his receiver from the telephone hook, a circuit is closed from the battery e, throu h the winding of the relay 0, limbs a and .of the telephone line of said party, the strand 7c and the winding of the relay'p, to ground. This will sufficiently energlze the relay p to cause it to attract its contact 12 and thereby break the circuit of the lamp p and cause its extinguishment, thereby indicating to the 0 erator that the called party has respon ed. In a similar manner, when the plug it was inserted in the jack of the substation A, the relays 0 and 0 were energized so as to close the circuit of the lamp 0 at the anvil 0 and together, thereby com leting the lam circult and causing it to e displayed. hen both lamps are thus displayed, it is a si nal to the operator for disconnection, an( as soon as she withdraws plugs h and i, the lamps o and will be extinguished and the parts returned to normal position.

Obviously, many alterations and modifications ma be made in the structure disclosed herein, without departing from the spirit and scope of my invention. I, therefore, do not WlSll'iiO be limited to the specific matter disclosed, but aim to cover, by the terms of the ap ended claims, all such alterations and mo ifications.

What Iclaim 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 office, a cord-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a signal associated with said connected line and cord-circuit, current sources of different potentials, a controlling electromagnet for said signal, means under the control of the subscriber for energizing said electromagnet by current from one of said sources, means under the control of the operator for energizing said electromagnet by current from another of said sources, and means responsive to the one energization to display said signal and to the other energization to efface said signal. I

2. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a call si nal associated with said line at the centra office, current sources of different potentials, a controlling electromagnet for said signal, means under the control of the subscriber for energizing said electromagnet by current from one of said sources, means under the control of the operator for energizing said electromagnet by current from another of said sources, and means responsive to the initial energization to display said signal and to the subsequent energization to efface said signal.

3. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a call si nal associated with said line at the centra office, current sources of relatively high and'low potentials, a controlling electromagnet for said signal, means under the control of the subscriber for energizing said electromagnet by current supplied from said low potential source, means under the control of the operator for displacing said low potential supply by a supply from said high potential source, and means responsive to the initial energization to display said signal and to the modified energization to efface said signal.

4. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making connection to said line, means for holding conversation over said line and cord-circuit, a signal, a controlling electromagnet for said signal, a battery, means for closing a circuit through anumber of cells of said battery, and an energizing Winding of said electromagnet, means for including a different number of cells of said battery in circuit With an energizing Winding of said electromagnet, and means responsive to the one energization to display said signal and to the other energization to efface said signal.

5. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making connection to said line, means for holding con versation over saidline and cord-circuit, a signal, a controlling electromagnet for said signal, a battery, means under the control of the subscriber for closing a circuit through a number of the cells of said battery and an energizing Winding of said electromagnet, means under the control of the operator for including a different number of cells of said battery in circuit With an energizing Winding of said electromagnet, and means responsive to the one energization to display said signal and .to the other energization to efface said signal.

6. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a signal, a controlling electromagnet for said signal, a battery, means under the control of the subscriber for closing a circuit through part of the cells of said battery and an energizing Winding of said electromagnet, means under the control of the operator for including a greater number of cells of said battery in series With said energizing Winding, means responsive to the former energization to establish one condition of said signal and means responsive to the latter energization to establish another condition of said signal. 7. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making'connection to said line, means'for holding conversation over said line and cord-circuit, .a signal, a controlling electromagnet for said signal, a battery, part of the cells of said battery and an energizing Winding of said electromagnet being in bridge of said telephone line, means at the substation for closing circuit through said bridge, means under the control. of the operator for closing a circuit through a different number of cells of said battery and an energizingwinding of said electromagnet, and means responsive to the different resulting 'energizations of said electromagnet to produce different operative conditions of said signal.

8. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making connection to said line, means for holding con versation over said line and cord-circuit, a signal, a controlling electromagnet for said signal, a battery, part of the cells of said battery and an energizing Winding of said electromagnet being in bridge of said tele phone line, means at the substation for closing a circuit through said bridge, means under' the control of the operator for closing a circuit through more cells of said battery and an energizing Winding of said electromagnet, and means responsive to the different resulting energizations of said. electromagnet to produce different operating conditions of said signal.

9. A telephone system comprising a telephone line extending from a substation to a central ofiice, a cord-circuit for making connection to said line, means for holding conversation over said line and cord-circuit, a signal,. a controlling electromagnet for said signal, a battery, part of the cells of said battery and an energizing Winding of said electromagnet'being in bridge of said telephone line, means at the substation for closing a circuit through said bridge, means un der the control of the operator for completing a circuit over a portion of the talking circuit and through a larger number of cells of said battery and an energizing Winding of said electromagnet, and means responsive to the different energizations of said electromagnet to produce different operating conditions of said signal. v

10. A telephone system comprising a telephone line extending from a substation to a central office, a cord-circuit for making connection to said. line, means for holding conversation over said line and cord-circuit, a

signal, a controlling electromagnet for .said signal, a battery, a tap from an intermediate point in said battery normally connected to phone line extending from a substation to a central oflice, a cord-circuit for making connection to said line, means for holidng conversation over said line and cord-circuit, a signal, a controllingelectromagnet for said signal, a battery, a tap from an intermediate point in said battery normally connected to the tip side of said line, a connection from one pole of said battery through an energizing winding of said electromagnet to the sleeve side of said line, a connection from the other pole of said battery to the sleeve side of said cord circuit, a supervisory relay Winding in said latter connection, and a second supervisory relay windin included in circuit between the tip side the cordcircuit and the intermediate tap of said bat terv.

12. In a telephone exchan e system, the combination with a telephone ine connecting a substation with the central ofiice and provided with a switching terminal thereat, a si al receiving electromagnet associated wlth said line having an energizing winding and source of current normall m circuit therewith adapted to energize sald magnet to a limited extent only to cause it to display its signal when the line circuit is closed at the substation, and a cord connecting apparatus adapted to make connection with said switching terminal and to establish a new path for the greater flow of current through said energizing winding and switching terminal to cause a greater energization of said magnet whereb the said signal is again efiaced when the sai line is switched for conversation.

13. In a telephone exchan e system, the combination with a telephone ine connecting a substation with the central ofiice and provided with a switching terminal thereat, a s' al receiving electromagnet associated with said line having an energizing winding and source of current norr'nall 1n circuit therewith adapted to energize said ma et to a limited extent onl to cause it to is lay its signal when the ine circuit is close at the substation, a cord connecting a paratus adapted to make connection with said switching terminal and to establish a new path for the greater flow of current through said energizing winding and switching terminal to cause a greater energization of said magnet whereby the said signal is again effaced when the said line is switched for conversation, a signal controlling electromagnet associated with said cord connecting apparatus and under the control of the substation switch when the telephone line is switched for conversation, a second-signal controlling electromagnet associated with said cord connecting apparatus and energized over the said circuit established by the connection of the cordcircuit to the tele hone line, and a supervisory signal joint y controlled by the said two electromagnets.

combination with a telephone line connecting a substation with the central office and provided with a switching terminal thereat, a si nal receiving electromagnet associated with said line having an energizing winding and source of current normally 1n circuit therewith adapted to energize said ma net to a limited extent only to cause it to display substation, cord connectingapparatus adapted to make connection with said switching terminal and to establish a new path for the ing winding and switching terminal to cause a greater energization of said magnet whereby the said signal is again eflaced when the said line is switched for conversation, and a signal controlling electromagnet associated with said cord connecting ap aratus and under the control of the substation switch when the tele hone line is switched for conversation.

15. n a telephone exchan e system, the combination with a telephone ine connecting a substation with the central ofiice, a cordcircuit at the central ofiice for making connection with said line, a signal receiving electromagnet associated with said line having an energizing winding connected to one side thereof, a normal connection extending from the other side of said line to a source of current of limited potential adapted to complete the circuit through said winding when the line circuit is closed at the substation to energize said magnet to a limited extent only to cause the display of its signal, and a connection from a source of current of greater potential to said cord-circuit and adapted to cause a greater flow of current through said energizing winding when the line is switched for conversation whereby the said signal is effaced.

16. In a telephone exchan e system, the' combination with a telephone line connecting a substation with the central ofiice, a cordcircuit at the central office for making connection with said line, a signal receiving electromagnet associated with said line havin an energizing winding connected to one si e thereof, a normal connection extending from the other side of said line to a source of current of limited potential adapted to complete the circuit through said winding when the line circuit is closed at the substation to energize said magnet to a limited extent only to cause the display of its signal, a connection from a source of current of greater potential to said cord-circuit and adapted to cause a greater flow of current through said energizing winding when the line is switched for conversation whereby the said signal is efiaced, and a signal controlling electromagnet associated with said cord-circuit and under the control of the substation switch when 14. In'a telephone exchange system, the

the telephone line is switchedfor conversation. 17. n a telephone exchange system, the

its signal when the line circuit is closed at the greater flow of current through said energizcombination with a telephone line connecting a substation with the central office, a cordcircuit at the central oflice for making connectionwith said line, a signal receiving electromagnet associated with said line having an energizing Windingconnected to one side thereof, a normal connection extending from the other side of said line to a source of current of limited potential adapted to complete the circuit through said winding when the line circuit is closed at the substation to energize said ma net to a limited extent only to second signal controlling electromagnet associated with said cord-circuit and energized over the said circuit established by the con nection of the cord-circuit to the telephone line, and a supervisory signal jointly controlled by the said two electromagnets.

18. In a telephone exchange system, the combination with. a telephone line connecting a substation with the central office, a cordcircuit at the central office for making connection with said line, a signal receiving electromagnet associated with said line having an energizing winding and source of current of limited potential in circuit therewith adapted to cause a limited energization of said'magnet to cause the display of its signal when the line circuit is closed at the substation, and a source of current of greater potential adapted to be included in circuit with said ener izing winding when the said line isswitche for conversation to cause an increased energization of said magnet to efface the said signal.

19. In a telephone exchan e system, the combination with a telephone ine connecting a substation with the central oflice, a cordcircuit at the central office for making connection with said line, a signal receiving electromagnet associated with said line having an energizing winding and source of current of limited potential in circuit therewith ada ted to cause a limited energization of sai magnet to cause the display of its signal -when the line circuit is closed at the substation, a source of current of greater potential adapted to be included in circuit with said energizing winding when the said line is switched for conversation to cause an increased energization of said magnet to efface the said signal, and a signal controlling electromagnet associated with said cord-circuit and under the control of the substation switch when the telephone line is switched for conversation.

20. In a telephone exchan e system, the combination with a telephone ine connecting a substation with the central office a cordcircuit at the central office for making connection with said line, a signal receiving electromagnet associated with said line having an energizing winding and source of current of limited potential in circuit therewith adapted to cause a limited energization of said magnet to cause the dis lay of its signal when the line circuit is c osed at the substation, a source of current of'greater potential adapted to be included in circuit with said energizing winding when the said line is switched for conversation to cause an increased energization of said magnet to efface the said signal, a signal controlling electromagnet associated withsaid cord-circuit and under the control of the substation switch when the telephone line is switched for conversation, a second signal controlling electromagnet associated with said cord-circuit and energized over the said circuit established by the connection of the cord-circuit to the telephone line, and a supervisory signal jointly controlled by the said two electromagnets;

21. In a telephone exchange system, the combination with a telephone line con.- necting a substation with a switching terminal at the central office, a switch at the substation for controlling the flow of current over the said line through the substation, a cord circuit at the central oflice adapted to. make connection with said switching terminal and to complete a circuit therethrough over said telephone line, a signal controlling electromagnet associated with said telephone line and normally responsive to currents therein controlled either by the substation switch or by the connection of the cord-circuit to the line at the central oflice, an energizing winding for said electromagnet permanently connected between one contact of said switching terminal and one terminal of the source of current and adapted to be energized over the corresponding strand of the cord-circuitand to cause the complete energization of said'electromagnet when the cord-circuit is connected to the line, a normal connection extending from an intermediate point of said source of current to the o posite side of the telephone line to secure a 1mitedenergization only of said electromagnet over the telephone line under the control of the substation switch when thecord-circuit is not connected to said line, a normally effaced line signal controlled by said electromagnet,

means for causing the display of the said. line signal when the said electromagnet is energized to a limited extent, and means for effacing said signal when the said relay is ener-- gized to a greater extent.

22. In a telephone exchange system, the combination with a telephone line connecting a substation with the central "oflice and provided with a switching terminal thereat, a switch at the substation for controlling the How of current over the said line through the substation, a signal controlling electromagnet associated with said telephone line having an energizing winding connected between one contact of said switching terminal and one terminal of a source of current, a connection extending from an intermediate point of said source of current to the opposite side of said telephone line adapted to cause a limited energization only of said electromagnet under the control of the substation switch to cause a limited movement only of the signaling mechanism associated with said electromagnet whereby the signal is displayed, and a cord-circuit at the central ofiice adapted to make connection with said switching terminal and to complete a circuit from the other terminal of said source of current through said energizing winding to cause a greater energization of said electromagnet 'whereby the said switching mechanism is ing an energizing winding connected between one contact of said switching terminal and one terminal of a source of current, a connection extendin from an intermediate point of said source 0 current to the opposite side of said telephone line adapted to cause a limited energization only of said electromagnet under the control of the substation switch to cause a limited movement only of the signaling mechanism associated with said electromagnet whereby the signal is displayed, a cord-circuit at the central office adapted to make connection with said switching terminal and to complete a circuit from the other terminal of said source of current through said energizing winding to cause a greater energization of said electromagnet whereby the said switching mechanism is caused to assume a third position to eflace said signal, and a si al controlling electromagnet associated with said cord-circuit and under the control of the substation switch when the telephone line is switched for convelsation.

24. In a telephone exchange system, the combination with a telephone line connecting a substation with the central office and provided with a switching terminal thereat, a switch at the substation for controlling the flow of current over the said line through the substation, a signalcontrolling electromagnet associated with said telephone line having an energizing winding connected between one contact of said switching terminal and one terminal of a source of current, a connection extending from an intermediate point of said source of current to the opposite side of said telephone line adapted to cause a limited energization only of said electromagnet under the control of the substation switch to cause a limited movement only of the signaling mechanism associated with said electromagnet whereby the signal is displayed, a cord-circuit at the central oflice adapted to make connection with said switching terminal and to complete a circuit from the other terminal of said source of current through said energizing winding to cause a greater energization of said electromagnet whereby the said switching mechanism is caused to assume a third position to efface said signal, a signal controlling electromagnet associated with said cord-circuit and under the control of the substation switch when the telephone line is switched for conversation, a second signal controlling electromagnet associated with said cord-circuit and energized over the said circuit established by the connection of the cord-circuit to the telephone line, and a su ervisory signal jointly controlled by the sai two electromagnets.

25. In a telephone exchange system, the combination with a telephone line connecting a substation with the central oflice and provided with a switching terminal thereat, a switch at the substation for controlling the flow of current over the said line through the substation, a signal controlling relay associated with said telephone line having an energizing winding connected between one contact of said switching terminal and one terminal of a source of current, a connection extending from an intermediate point of said source of current to the opposite side of said telephone line adapted to cause a limited energization only of said relay under the control of the substation switch to cause a limited movement only of the relay contacts and to complete a circuit through the signal, and a cord-circuit at the central oflice adapted to make connection with said switching terminal and to complete a circuit from the other terminal of said source of current through said energizin winding to cause a greater energization 0 said relay whereby the relay contacts are caused to assume a third position to efface said signal, I

26. In a telephone exchange system, the combination with a telephone line connecting a substation with the central office and provided with a switching terminal thereat, a switch at the substation for controlli the flow of current over the said line throug the substation, a signal controlling relay associated with said telephone line having an energizing winding connected between one contact of said switching terminal and one terminal of a source of current, a connection extending from an intermediate point of said source of current to the opposite side of said telephone line ada ted to cause a limited energization only 0 said relay under the control of the substation switch to cause a limited movement only of the relay contacts and to complete a circuit through the signal, a cord-circuit at the central office adapted to make connection with said switching terminal and to complete a circuit from the other terminal of said source of current through said energizing winding to cause a greater energization of said relay whereby the relay contacts are caused to assume a third position to efiace said signal, and a signal controlling electromagnet associated with said cord-circuit and under the control of the substation switch when the telephone line is switched for conversation.

27. In a telephone exchange system, the combination with a telephone line connecting a substation with the central office and provided with a switching terminal thereat, a switch at the substation for controlling the flow of current over the said line through the substation, a signal controlling relay associated with said telephonejine having an energizing winding connected between one contact of said switching terminal and one terminalof a source of current, a connection extending from an intermediate point of said source of current to the opposite side of said telephone line adapted to cause a limited energization only of said relay under the control of the substation switch to cause a limited movement only of the relay contacts and to complete a circuit through the signal, a

cord-circuit at the central ofiice adapted to make connection with said switching terminal and to complete a circuit from the other terminal of said source of current through said energizing winding to cause a greater energization of said relay whereby said con tacts are caused to assume a third position to etface said signal, a signal-controlling electromagnet associated with said cord-circuit and under the control of the substation switch when the telephone line is switched for conversation, a second signal controlling electromagnet associated with said cord-circuit and energized over the said circuit established by the connection of the cord-circuit to the telephone line, and a supervisory signal jointly controlled by the said two electromagnets.

In witness whereof, I hereunto subscribe my name this 1st day of November, 1907.

'HARRY G. WEBSTER.

Witnesses:

JAMES G. KELLocc, G. E. MUELLER.

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