US802671A - Telephone-exchange system. - Google Patents

Description

PATENTED OCT. 24, 1905.

H. G. WEBSTER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED FEIB.14. 1903.

ITIVETTEIF WET 2) E E EFF u RHUFUEBH Be it known that 1, HARRY Gr. WnBs'rnR, a relay is in its normal unattracted position, the citizen of the United States, residing at Ghienergization of the line-relay causes an actuacago, in the countyof (look and State of Illitionof its armature to close circuit through nois, have invented a certain new and useful the line-signal lamp and switch-contacts of Improvement in Telephone Exchange Systhe cut-oif relay. The connection of the cord tems, of which the following is a full, clear, connecting apparatus with theline whose sig- 6O concise, and exact description, reference benal-larnp has been caused to glow causes the ing had to the accompanying drawings, formclosure of a circuit of decreased resistance ing a part of this specification. through one winding of the cut-oi? relay, My invention relates to telephone-exchange whereby the balanced differential energization systems, and particularly to systems in which of the cut-01f relay is destroyed to cause an 5 a common source of currentlocated at the cenenergization thereof and a consequent actuatral station is employed to furnish current both tion of the armature ot' the cut-off relay. The for the operation of the necessary signaling actuation of this armature serves to break the apparatus and the substation-transmitters local circuit through theline-signallamp. The

My invention relates more particularly to cord-circuit adapted for use in connection with such systems in which a so-called diiferenthe line-circuit thus described may be of any tial cut-oli' relay may be employed. suitable design adapted to cause the proper My invention provides a system in which operation of the differential cut-0d relay and there are no relay-contacts included in the to serve the customary uses of cord connecttalking-circuit. The limbs of the telephoneing apparatus in connecting for conversation 7'5 line extending froma substation to an exany desired substations. change are permanently connected with the My invention will be best understood by terminals of the common source of current. reference to the accompanying diagrammatic The well-known spring-jacks employed in drawing, in which at each of the substations making connections between subscribers may A and B is shown a common form of substabe permanently connected with the telephonetion apparatus comprising a switch-hook 1, lines, whereby a system of greatsimplicity adapted when in its normal depressed posiand reliability in operation is secured. tion, due to the weight of the receiver 2, to My invention also provides improved means serially connect in circuit with the limbs 3 and whereby a central-station operator may test 4 ot' the telephone-line the calling signal-bell the operative condition of a subscribers line 5 and the condenser 6. Upon the removal to know whether or notitis busy. The mech of the receiver from the switch-hook the latanism associated with the cut-oft relay comter assumes a position adapted to close a cirprises a single armature and back contact cuit between the telephone-limbs 3 and 4: therefor. through a battery-transmitter T and the priin accordance with my invention I provide mary 8 of an induction-coil, whose secondary at the central station a common source of cur- 9 is connected with the receiver 2. The limbs rent, to opposite terminals of which the two 3 of the telephone-lines extend each to the limbs of a line from each substation are persubstation and there through a winding 10 of manently connected, one limb serially includthe differential relay 11 to the positive grounding a line-relay and a coil of a diiierentiallyed terminal of the common battery 12. The wound cut-oii' relay, the other limb including limbs 4 of the telephone-lines extend each to the other coil of the diiferential relay. the negative pole of the battery 12, there be- The multiple spring-jacks used in connecing serially included in each of said limbs the tionwith the customary cord-circuit in conwinding 13 of the dilierential relay 11 andwo 'necting subscribers are permanently connectthe winding of a line-relay 14:. The answered with the limbs of the telephone-line between ing-jack 15 and the multiple calling-jacks 16 thesubstation and the cutoii' and line relays. 16 are permanently connected with the tele- Aline-signal is. provided,desirably in the form phone-line, as shown, the tip contacts 17 17 of a small incandescent lamp, whose local cirbeing shown in this instance connected with To all whom it mag concern:

cuit is jointly controlled by the line and cutnurr nn STATE$FENT OFFICE.

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE STRON- BERG-OARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCH- ESTER, NEW YORK, AGORPORATION OF NEWV YORK.

TELEPHONE-EXCHANGE SYSTEM- Specification of Letters Patent. Application filed February 14,1903. Serial No. 143,304.

No. 802,671. Patented Oct. 24, 1905.

ofi' relays. When the armature of the cut-oif the limb 4, while the sleeve-contacts and thirnblcs 18 18 are connected with the limb A line-signal lamp 19 is adapted to be illuminated through a local circuit containing the battery 12, the continuity of this circuit being jointly controlled by switch-contacts of the cut-01f relay and the line-relay. 'lVhen the armature 20 of the cutoff relay is in its normal unattracted position, the energization of the line-relay 14: causes the attraction of its armature 21 to cause the closure of the local circuit adapted to illuminate the lamp 19. The energization of thecut-oif relay causes the attraction of the armature 20 to break this circuit.

The cord-circuit employed is shown as comprising an answering-plug 22 and a callingplug 23, whose tip-contacts are suitably connected through a cord-strand 24, including the condenser 25,and whose sleeve-contacts are normally connected through the sleevestrand 26.

The customary ringing and listeningkey 27 is provided, a manipulation of this key in one direction serving to connect the opera- 5 tors telephone set 28 in bridge of the cordcircuit, while a manipulation of the key in a reversed direction serves to connect the ring ing-generator 29 between the cord- strands 24 and 26, leading to the calling-plug 23.

A circuit in shunt of the condenser 25 includes the supervisory rela s 30 and 31, the common terminal of which is connected through a resistance 32 with the negative pole of the common battery 12. A supervisory controlling-relay 33 is connected between the negative pole of the battery 12 and the sleevestrand 26 of the cord-circuit. The armature 3 1 of this supervisory controllingrelay when in its attracted position, as shown, serves to connect the positive pole of the battery 12 with the supervisory signal-lamps 35 and 36, the continuity of the circuit through the lamp 35 being established through the armature 37 of the supervisory relay 30 when in its normal unattracted position, and the continuity of the circuit through the supervisory signallamp 36 being similarly established by the armature 38 0f the relay 31.

The operation of my improved system may be described as follows: The removal of the receiver at substation A from its switch-hook causes theclosure of a' circuit, which may be traced as follows: from the positive pole of the battery 12 through the coil 10 of the differential relay and the limb 3 of the telephone-line to the transmitter andprimary winding of the induction-coil at the substation A through the limb 4 of the telephoneline, the winding 13 of the differential cut-ofi" relay, and the winding of the line-relay 14, to the negative pole of the battery 12 The closure of this circuit does not cause the actuation of the armature of the cut-off relay on account of the difierential relation of the windings 10 and 13. The closure of the circuit through the line-relay. however, causes the attraction of its armature to close the'local battery-circuit through the line-signal 19. The operator apprehending the signal given by the illumination of the lamp 19 inserts the answering-plug 22 within the answering-jack 15, thereby connecting her cord-connecting apparatus in circuit with the limbs 3 and L of the line leading to substation A. The insertion of the plug 22 immediately causes the closure of a circuit, which may be traced as follows: from the positive pole of the batter 12, through the winding 10 of the differential cut-off relay 11, to the sleeve-spring 18 of the, answering-jack. 15, to the sleeve-contact of the plug 22, through the sleeve-strand 26 and the winding of the supervisory controlling-relay 33, to the negative pole of the battery 12. Thus a circuit of decreased resistance is closed through the winding 10 of the differential cut-off relay, causing a net energization of the relay-core, whereupon the cut-off relay-armature 20 is attracted from its back contact connected with the ground, as shown. Since the local circuit adapted to cause the illumination of the lamp 19 includes the ground connection between the back contact of the armature 20 and the groundedside of the battery' 12, this actuation of the cut-off relay-armature breaks the local circuit through the linesignal 19, whereupon the,- lamp is extinguished. This circuit established hythe insertion of the plug within a jack also causes the energization of the relay 33 to attract its armature 3 1, whereupon the supervisory sig:

nal-lamps 35 and 36 are connected with the positive pole of the battery 12. The armature 38 of the cut-off relay 31 being in its normal unattracted position completes the circuit through the lamp 36, whereupon thisv supervisory signal-lamp is caused to glow. The receiver at the substation A being removed from its hook, closes a circuit through the supervisory relay 30, which may be traced as follows: from the negative pole of the battery 12, through the resistance 32, the supervisory relay 30, the tip-strand. 24 of the cordcircuit, the tip-contact of the answering-plug 22, the tip-spring of the answering-jack 15, the limb 4 of the telephone-line, the primary coil 8, the transmitter 7, the limb 3 of the telephoneline, and the winding 10 of the cut-off relay. The consequent energization of the relay 30 causes the attraction of its armature 37 to open the otherwise completed circuit through the supervisorysignal-lamp 35. This lamp,which is intended to apprise the operator of the operative condition of the subscribers substation apparatus is therefore not permitted to glow upon the insertion of the answeringplug within the answering-jack, The operator manipulates her listening-key to connect her telephone set in bridge of the cord-circuit connected with the calling-substation.

Upon ascertaining that the subscriber at subscriber at substation relay 33 and the coil of the differential cut-off relay associated with the telephoneline running to substation B. An actuation of the armature of this cut-ofi' relay is thereby caused to immediately open a circuit, which otherwise might be closed through the line-signal 19,'corresponding to the substation B. Upon the removal of the receiver at substation B from its switch-hook a circuit is closed through the supervisory relay 31, the

3 the attraction of consequent'energization of this relay causing the armature 38 to extinguish the lamp 36. Either subscriber upon finishing the conversation with the other replaces his receiver upon its switch-hook, thereby opening thepreviously-traced circuit through the corresponding supervisory relay or 31, as the case-may be. The armature 34 of the supervisory controlling-relay 34 being still in its abnormal attracted position,

due to the continuance of the insertion of the plugs within the line-jacks, the release of an armature 37or 38 of the supervisory relay causes the closure of the local circuit through the corresponding supervisory signal-lamp 35 or 36, whereby the latter is caused to glow, thereby giving the operator a signal that the connecting-plug may be withdrawn from the corresponding line-jack. The removal of the cord-connecting plug causes the restoration of the line and cut-off relays to their normal condition. Upon the removal of both plugs the supervisory relays and the supervisory controlling-relay 33 are also restored to their normal condition. i

' he means employed by an operator to see before inserting a plug within a jack is as follows: It

will be seenthat upon the manipulation of the listening-key to connect the operators telephone set in bridge of the cord-circuit the connection through the supervisory relay 31 between the negative pole of the battery and the tip-strand 24. of the cord-circuit is broken.

There is connected with the contact39 a conductor leading through a test-winding 40 in inductive relation with,the induction-coil of the operators telephone set to the grounded side of the battery 12.

It will be seen that under normal conditions in which the line running to substation B is -not in use the test-contacts 18 of the associated multiple jacks are connected-with the grounded side of the batteryby conductors eludes the coil 10 of the potential above that through which 'no current is flowing, and

therefore these test-contacts are at the zeropotential of the ground. Upon the insertion of a plug of a cord-circuit within any pf 'the multiple-jacks a circuit is closed which inassociated cut-off relay and the coil of a supervisory controlling-- relay 33. The test-contacts are all connected with this circuit. Upon the connection of the cord-circuit with a-line all of the associated test-contacts are therefore raised in of the ground. 'While the tip-strand of an idle cord-circuit is normally at the potential of the negative terminal of the common battery, still upon the manipulation of the listening-key the connection between the part of the tip-strand leading to the testing-tip contact and the negative side of the battery is brolzen, and ,t is part of the tip-strand is connected ,through' the test-winding 40 with the positive grounded side of the battery flows through the cord-circuit and when the listening-key is thus manipulated, the tipof the calling-plug 23 is charged to thezero potential of the grounded side of the battery 12. In making a test of a line when the testthimbles are at the zero potential of the ground no current will be caused to flow between the testing-tip contact and the test-thimble. Therefore no clickwill be heard in the operators receiver, the operator knowing thereby that the tested line'is idle. If,on the other hand, the line is busy and, as previously described, the test-thimbles have been raised in potential above that of the ground, the connection of the tip of the calling-plug and a testrthimble will cause a current to flow through the testwinding 40, which induces a current in the secondary winding of the induction-coil connected with-the operators telephone, whereupon a click in the operators receiver notifies her of the busy condition of the tested line.

W hile I have herein shown and described one particular embodiment of my invention, it will be apparent to those skilled in the art that many modifications thereon may be made without departing from the spiritof my invention. I do not, therefore, .wish to limit myself to the precise disclosure herein set forth; but,

Having described my invention, Y. claim as new and desire to secure by Letters Patent- 1. In a telephone-exchan ge system, the combination with a telephone-line extending by its 12. When no current limbs from a substation to an exchange, of a source of current at the exchange, to the terminals of which are permanently connect-ed the limbs of said line, a line-relay permaing saidline with another for convcrsation,and means whereby the connection of saidv cord connecting apparatus with said line causes an actuation of said cut-off relay to destroy the substation control of the line-signal. ,2. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said'lines, aline-relay serially included in circuit with one of said line-limbs, a difierential cut-ofi relay having two windings, each permanently serially included in a limb of said line, a line-signal jointly controlled by said line and cut-ofi' relays, cord connentin g apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line causes an actuation of said cut-off relay to destroy the substation control of the line-signal.

3. In a telephone-exchange system, the com bination with atelephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said line, a line-relay permanently included in circuit with one of said line-limbs, a differential cut-0E relay having two windings, each permanently included in a limb of.

said line, a line-signal jointly controlled by said line and cut-off relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line causes an actuation of said cut-oft relay to destroy the substation control of the line-signal,

,- 4. Inatelephone-exchangesystem,thecombination with a telephone-line extending by its i limbs from a substation to an exchange, of'a, source of current at the exchange, to the ter-' minals of which are permanently connected the limbs of said'lines, a line-relay included in circuit with one of said line-limbs, a differential cut-ofi relay having two windings, each permanently included ina limb of said line, a

i line-signal jointly controlled by said line and cut-off relays, cord connecting apparatus for connecting said line with another forconversation, and means whereby the connection of said cord connecting apparatus with said line,

causes an actuation of said cut-off relayv to de-,

stroy the substation control of the line-signal. 5. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current as the exchange, to the terminals of which are permanently connected the limbs of said line, a line-relaypermanently serially included in circuit with one of said line-limbs, a differential cut-off relay having two windings, each serially included in a limb of said line, a line-signal jointly controlled by said line and cut-01f relays, cord connecting apparatus for connecting said line with another for co'nversatiomand means whereby the connection of said cord connecting apparatus with said linecauses an actuation vof said cut-01f relay to destroy theflsubstation control of the line-signal.

6. I In a telephone-exchange system, the com bination with a telephone-line extending by its limbs from a substation to an exchange, of'a source of current at the exchange,to' th eterminals of which are-permanently connected the limbs of saidline, a linewrelay permanently serially included in 'circuitgwith one of .said line-limbs, a differential cut-off relay hay us,

two windings permanentlyserially included in circuit with a telephone-line, a line-signal jointly controlled by said line and cut-olf'relays, cord connecting apparatusfor connecting said line with another forconversation, means whereby the connection or said ,cordc'onnecting apparatus with said line causes an actuation of the said cut-off relay to destroy the substation control ofthe line-signah I 7 In a telephone-exchange system, thecombination with a telephone-line extending its limbs from a substationto. an'exchangej of a source of currentat the exchange, to the tervminals of which are permanently connected the limbs of said line, a line-relay included in circuit with one limb of said line, a cut-off relay having two differential windings serially included in thelimbs of said line, a line-signal jointly controlled by saidline and cut-0E relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line causes an'actuation with said cut-off. relay to destroy the substation control of the line-signa I 8. In a'telephone-exchange,the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to the terminals or'which are connected the limbs of said line, a line-relay permanentlyiincluded. in a linecircuit, a cut-ofi relay having two differential windings, each permanently serially included in a limb of saidline, a line-signal jointly controlled by said line and -cut-ofi relays, cord connecting apparatus for connecting said line with another for conversation and]. means whereby theconnection ofsaid cord-connecting apparatus with said line causes an actuationof said cut-0c relay toidestroy the substation control ofsaid line-signal, i

j 9. Inatel'eph"neyexchangesystem, the combination with a telephone-line extending by its limbs from a substation toanexchange, of a source of current at the exchange, ,to the terminals of which are vpermanently connected the limbs of said line, a line-relay permanently serially included in circuit with one of said line-limbs, a difi'e'rential cut-oif .relaylhaving 5 of decreased its limbs from a substation to an exchange,

of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said line, a line-relay serially included in circuit with one of said line-limbs, a difierential cut-otl'rela'y having two windings, each permanently serially included in a limb of said line, a line-signal jointly con,- trolled by said line and cut-ofi' relays, cordconnecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting .apparatus with said line closes a circuit resistance through one winding of said cut-ofl? relay to cause an actuation other for conversation,

thereof.

1 1. In a telephone-excl] ange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said line, a line-relay permanently included in circuit with one of said line-limbs, a diiferential cut-off relay having two windings, each permanently included in a limb of said line, a line-signal jointly controlled by said line and cut-ofi relays, cord connecting apparatus for connecting said line with anand means whereby the connection of said cord connecting apparatus with said line closes a circuit of decreased resistance through one winding of said cut- 0E relay to cause an actuation thereof.

12. In atelephone-exchange system,the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the-exchange, to the terminals of which are permanently connected the limbs of said line,'a line-relay included in circuit with -one of said line-limbs, a differenversation, and means whereby tial cut-off relay having two windings, each permanently included in a' limb of said line, a line-signal jointly controlled by said line and cut-ofl relays, cord connecting apparatus for connecting said line with another for conthe connection of said cord connecting apparatus with said line closesa circuit of" decreased resistance through one winding of said cut-oif relayto cause an actuation thereof.

13. In a telephone-exchange system, the combin'ation-witha telephone-line extending by its limbs fromia substation to an exchange,

of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said line, a line-relay permanently serially included in circuit with one of said line-limbs, a diiferential cut-01f relay having two windings, each serially included in a limb of said line, a line-signal jointly controlled by said lineand cut-otf relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line closes a circuit of decreased resistance through one winding of said cut-ofl relay to cause an actuation thereof.

14. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to the terminals of which areperman ently connected the limbs of said line, a line-relay permanently serially included in circuit with one of said line-limbs, adilierential cut-ofl relay having two windings permanently serially included in circuit with a telephone-line, a line- ,signal jointly controlled by said line and cutoff relays, cord connecting apparatus'for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line closes acircuit of decreased resistance through one winding of said cut-off relay to cause an actuation thereof.

15. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said line, a line-relay included in circuit with one limb of said line, a cut-off relay having two difierential windings serially included in the limbs of said line, a linesignal jointly controlled by said line and cutoff relays, cord connecting apparatus for connecting said line with another for conversa-' tion, and means whereby the connection of said cord connecting apparatus with said line closes a circuit of decreased resistance through one winding of said cut-ofl' relay to cause an actuation thereof.

16. In a telephone exchange,the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to theterminals of which are connected the limbs of said line, a line-relay permanently included in a line circuit, a cut-off relay having windings, each permanently serially included in a limb of said line, a line-signal jointly controlled by said line and cut-off relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection ing apparatus with said line closes apircuit of decreased resistance through one winding of said cut-ofirelay-to cause anactuation thereof.

of said cord connect- 1 2 two diiferential 17. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange,

, of a source of current at the exchange, to the R terminals of which are permanently connected the limbs of said line, a spring-jack having contactspermanently connected to the limbs of said line, a line-relay permanently serially included in circuit with one of said line-limbs, a difi'erential cut-ofi relay having two windings, each permanently serially ineluded in a limb of said line, a line-signal jointly controlled by said line and cut-01f relays, cord connecting apparatus for connectand means whereby the connection of said cord connecting apparatus. with said line causes an actuation of said cut-elf relay to destroy the substation control, of the linesignal.

18. In a telephone-exchange system, the combination with a telephonc line extending by its limbs from a substation to an exchange,

, of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said lines, a spring-jack having contacts permanently connected to the limbs of said line, a linerelay serially included in circuit with one of said line-limbs, a difl'erential cut-oil relay having two windings, each permanently serially included in a limb of said line, a line-signal jointly controlled by said line and cut-off relays, cord connecting apparatus for connecting said line with another for conversation, and means wl ereby the connection of said cord connecting apparatus with said line causes an actuation of said cut-off relay to destroy the substation ential cut-ofi' relay having two windings, each i 5 \permanently included in a limb of said line,

a line-signal jointly controlled bysaid line and cut-ofi' relays, cord connecting apparatus for connecting said line with another for-conversation, and means whereby the connection of said cord connecting apparatus with said line ,stroy the substation control of the line-signal.

20. In a telephone-exchange system, the

, combination with a telephone-line extending by its lim bs from a substation to an exchange, of a source of current at the exchange, to the terminals of which arepermanentIy connected ,th 1i,mlQS.Of said line, a spring-jack having ,qcontacts permanently'connected to the limbs L 5 of said lline, a line -relay included in circuit ing said line with another for conversation,

causes an actuation of said cut-oft relay to deconnected to the llmbs of said line, a line-rewith one of said line-limbs, a differential cutofi relay having two windings, each permanently included in a limb of said line, a linesignal jointly controlled'by said line and cutoff relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line causes an actuation of said cut-off relay to destroy the substation control of the line-signal.

21. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange, to the terminals of which are permanently connected the limbs of said line, a spring-jack having contacts permanently connected to the limbs of said line, a line-relay permanently serially included in circuit With one of said line-limbs, a difl'erential cut-off relay having two windings, each serially included in a limb of said line, a line-signaljointly controlled by said line and cut-off relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line causes an actuation of said cut-off relay to destroy the substation control of the line-signal.

22. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the ex change, to the terminals of which are permanently connected the limbs of said line, a spring-jack haying contacts permanently connected to the limb of said line, a line-relay permanently serially included in circuit with one of said line-limbs, a difi'erential cutoff relay having two windings permanently serially included in circuit with a telephoneline, a line-signal jointly controlled by said line and cut-oil relays, cord connecting apparatus for connecting said line with another for conversation means whereby the connection oi said cord connecting apparatus with said line causes an actuation of the-said cutoff relay to destroy the substation control of the line-signal.

23. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an ex .change, of a source of c nrrent at the exchange, to the terminals of which are permanently connected the l mbs of said hne, a springack havmg contacts permanently lay included in circuit with one limb of said line, a cut-off relay having two differential windings serially included in the limbs of said line, a line-signal jointly controlled by said line and cut-off relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting appathe limbs of. said line, a line-relay permanently included in a linecircuit, a cut-off relay having two differential windings, each permanently serially included in a limb of said line, a line-signal jointly controlled by said line and cut-oft relays, cord connecting apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line causes an actuation of said cut-off rela to destroy the substation control of said line-signal.

25. In a telephone-exchange system, the

combination with a telephone-line extending byitslimbsfrom a substation to an exchan e, or a source of current at the exchange, to t e terminals of which are ermanently connected the limbs of said ine, a spring-jack havin tip and sleeve contacts permanently directy connected with the limbs of said line, a line-relay permanently serially included in circuit with one of said line-limbs,

a differential cut-ofl relay having two windin s,,each permanently serially included in a" imb of said line, a linesignal jointly line and cut-oil relays, cordconnecting apparatus for connectin said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line closes a circuit of decreased resistance through one winding of said cut-0H relay to cause an'actuation thereof.

26. In a telephone-exchange system, the

combination with a telephone-line extending its limbs froma substation to an exchange, of a source of current at the 'exchange,'to the terminals of which are permanently connected the limbs of said line, a spring-jack having tip and sleeve contacts ermanently directly connected with the lim s of said line, a line relay serially included in circuit with one of said line-limos, a difierentia cut-off relay having two windings, each permanently serially included in .a-limb of said line, a linesifgnal jointly controlled by said line and out o relays, cord connecting apparatus combination with a telephone linc extending for connecting said line with another for converby its limbs from asubstation to an exchan e, of a source of current at the.exchango;to t 1e terminals of which are permanently connect-. ed the limbs of said line, a spring-jack having tip and sleeve contacts ermanently directly connected with the liml is of-said line, a linerelay ermanently included in circuit with one 0 said line-limbs, a differential cut-off relay havin nentl inclu ed in a limb 0 said line, a linesiigna jointly controlled by said line and cut 0 relays, cord connecting apparatus for contion, and means whereby the connectionof said cord connecting a paratus with said line closes a circuit of ecreased resistance through'one winding of said cut-off relay to cause an actuation thereof.

combination with a telephone-line extending by its limbs from a substation to an exchan e, oi' a source of current at the exchange, to t e terminals of which are permanently connected the limbs of said line, aspring-jack having tip and sleeve contacts permanently directly connected with the limbs of said line, a line-relay included in circuitwithone of said line-limbs, a differential cut-off relay havin two windings, elude in a limb ofsaid line, a line-signal jointly controlled-by said line and cut-oil" reays, cord connecting a paratus for connecting said line with anot 'and means whereby. the connectionof said cord connecting apparatus with said line closes a circuit of decreased resistance through one winding of said cut-off relay to cause an actuation thereof. y

29. In a telephone-exchange system, the combination with a telephone-line extending by its limbs fromasubstation to an exchange, of a source of current at the exchange, to t 1e terminals of which are permanently connected the limbs of said line, a spring-jack ing tip and sleeve contacts permanently dia line-relay permanently serially included in tial cut-ofl rela having two windings, each serially include tion, and' means whereby the connection of said cord connecting a paratus with said line closes a circuit of ecreased resistance through one winding of said cut-oil? relay to cause an actuation thereof.

30. In a telephone-exchange system, the combination with a telephoneline extending by its limbs from a substation to an exchan e,

terminals of which are permanently connecttwo windin s, each perma-' 28. In a telephone-exchange system, the

rectly connected with the limbs of said line,

circuit-with one of said line-limbs, a difierem necting said line with another for conversaeach permanently inf er for conversation,

Ioo

hav-j.

signal jointly controlled by said line and cute I o cord connecting apparatus for connecting said line with another ,for conversa-i;

of a source of current at the exchange, to t e rectly connected with the limbs of said line,

v a lin e-relay permanently serially included-in circuit w th oneof said line-limbs, a dfierenjtial cutoff relay having two windings permanently serially included in circuit with a teleplione line; a line signal jointly controlled bysaid lineandcutbfl relays, cord connecty, ing apparatus for connecting said line with another for conversation, and means whereby the connection of said cord connecting apparatus with said line closes a circuit of .de-

creased resistance through one Winding of said cut-oil relay to cause an actuation thereof. 31. In a telephone-exchange system, the

combination with a telephone-line extending 1 by its limbs from a substation to an exchange, or a source of current at theexchange, the

terminals of which are permanently connected withjthe limbs of said line, a spring-jack having tip and sleeve contacts permanently directly connected with the limbs ot said line,

' a line-relay included in circuit with one limb of said line, a cut-off relay having two differ- 3 entialwindings serially includediii the limbs ofsaid line, a line-signal jointly controlled by said line'aiid cut oii relays, cord connecting apparatus for connecting said line with another for conversatiomand means whereby the connection of said cord connecting appara'tus withsaid line closes a circuit of decreased resistance through one winding ofsaid cut-off relay to cause an actuation thereof. In a. tele 'ihoiie-exchange, the combinalimbs from a substation to an exchange, of a source of current at theexchaiigc, to the tern'iinals of which are connected the limbs of said line, a spring-jack havingtip and sleeve line, aline-signal jointly controlled by said line and ciit oii' relays, cord connecting apparatus foicoiiiiecting saidline with another ,[forconversation,and means whereby the concombinationwith :Melephcme-line extending. byitslinibs iroiii a substation to an exchange,

nectioii of said cord connecting apparatus with said line closes a circuit of decreased resistance through one winding of said cut-oil relay to cause'zin actuation thereof.

33. In a'telephone-exchange systennthc of a source ofcurrent at the e whange adapted to supply current to the subsLationtransinit entia'l cut-oif relay permanentlyserially included between oneteriniiial oi thelsource oi current'and thelsubstation, a second winding of saiddifterential'relay permanently serially inciuded between the other terminal of the source of current and the substation, a linesignal jointly controlled bv said line and said 'ferential cut-off tion with. a telephi'ine-line extending by its "connected in said line-relay, and a test-contact permacut-ofi' relays, and a spring-jack permanently connected with said line.

3i. In a telephone-exchange system, the

combination with a telephone-line extending.

by its limbsfroma substation to an exchange, of a source'of current at the exchange adapted to supply current to the substation-transmitters, a line-relay and one winding of a difrelay permanently included between one terminal of the source'of current and the substation, a "second winding of said differential relay permanently included between the other terminal of the source of current and the substation, a line-signal jointly controlled by said line and said cut-off relays, and a spring jack permanently connected with said line.

35. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange adapted to supply current to the substation-transmitters, a line-relay and one winding of a differential cut-ofi' relay serially included between one terminal of the source of current and the substation, a second winding of said difi'erential relay serially included between the other terminal of the source of current and the substation, a local line signal circuit jointly controlled by the armatures of said line aiid'said cutoff relays, and a spring-jack permanently connected with said line.

36 In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of a source of current at the exchange adapted to supply current to the substation-trans mitters, a line-relay and one winding of a differential cut-ofi relay included between one terminal of a source of currentand the substation, a second winding of said diiierential cut-oil relay included between the other terininal of the source of current and the substation, a local line-signal circuit jointly controlled by the arniatures of said line and said cuto i' relays, andaspring-jack perinanently connected with said line.

37, In a teleglmne-excha'nge system, the

combination wit 1' a telephone-line extending by itslimbs from a substation to an exchange, of a source of current at the exchange adapted to supply current to thesubstation-transmitters, a line-relay and one winding of a differential cut-cit relay permanently serially inr'aluded in 'Oil'CllitbGtWQOn one terminal of the source-of current and the substation, a

second winding of said difi'erential' relay peri'nanently seriallyincludedv between the other terminal of'the source of current and the substation, a line-signal jointly controlled by said line andcut-ofi' relays, a spring-jackhaving a contact permanently with the limb of'the line included pently connected with the other limb of said 38. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from asubstation to an exchange, a source of'current at the exchange adapted to supply current to the substation-transmitters,-a line-rela and one winding of a dif- V T ferential cut-ofl re ay'included in circuit between one terminal of the source of current and the substation, a second winding of said. difierential relay permanently senally in cluded between the other terminal of the source ofcurre'ntand the substation, alocal line-signal circuit jointly controlled by the armatures of'said line and cut-off relays, a spring-jack having a contact fiplrmanently connectedwith the limb of the e included insaid line-relay, and a test-contact permai' ently connected with the other limb of said me.

v 39. In axtelephoneexchange system, the combination with a telephone-line extending b its limbs from a substation to an exchange, oi a source of current at the exchange adapted to supply current to the substation-trans mitters,,a line-relay and one winding of a dif-' 'ferential cut-ofl' rela permanently serially included in a circuit etween the one termnal of the source of current and the substa tion, a second winding oi said diilerential reother lim v 40. In a telephone-exchange system, the' lay included between the other terminal of the source of (current and thesubstation, a

line-signal jointly controlled by said line and cut-ofl rela s, a springzj ack havin a contact Egrmanent y connecte with the mb of the e-included in said line-relay, and a testcontact ermanently of said line.

combination with a telephone+line extending byits limbs from a substation to an exchange,

a source of current at the exchange adapted to supply current to the substatiomtransmitters, a hne-rela and one winding of a differential cutoff re ay included in circuit b'etween one terminal of the source of current andthe substation, a secondwindin of said diiferentin relay included between t e other terminal 01 the source of current and the sub station, a local line-signal circuit jointly controlled by the armatures of said line and cutofi relays, a spring-jack havin a contact manently connected with thelimb of the ine included in said line-relay, and a test-contact permanently connected with the other limb of said line.

.41. In a telephone-exchange system, thecombination with a telephone-line extending b its limbs from a substation to an exchange,-

' o a source of current at the exchange adapted to supply current to the substation-transmitters, a line-relay and one winding of a differential cut off relay serially included in circuit between one terminal of the source of connected with j the current and the substation, a second winding of said difierential relay-serially included be tween the other terminal ofthe source of current and the substation, af local line-signal circuit jointly controlled by. the armature, oi

said line and cut-off relays, a springj ack hav ing acontact permanently connected with one limb of the line included in said line-renected with the other limb of said line.

i2. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange,

voia source of current at the-exchange adaptpermanently connected with the otherlimb of said line.

43. In a telephone-exchange system, the combination with a telephone-line extendlng lay, andv a testecontact permanently cont 4 b its limbs from a substation to an exchange,

.o a source of current at the exchange adapt ed to'sup ly-current to a substationtransmitter, a inc-relay and-one winding of adifferential cut-off relay permanently serially included in one limb of said line between one terminal of the source of current and the substation, a second windin of said difierential' relay ermanently seria included in the second limb of said line etween the other terminal of the source of current and a substation, .a line-signal jointly controlled b said line and cut-off relays, and a spring-jac having one contact permanently connected with said first line-lira between the substation and the line and cut-01f rela s directly and having a test-contact permanentl irectl connected with the second limb 0 said line g relay.

44. In a telephone-exchange system, the combination with a telephone-line extending b its limbs from a substation to an exchange,

etween said substation and saidcut-off o a source of current at the exchange adapted to supply current to the substation-transmitters, a line-relay and one winding of? a differential cut-off relay serially included between one terminal of the source of current and the substation, a second winding of said differential relay serially included etween the other terminal of thesource of current and the substation, and a local line-signal circuit of said e and cut-off relays.

jiglintly controlled by the armatu'res 45. In a telephone-exchange Sy'St0m,' tl:1 :-O

combination with a telephone-lineextending station, and a local line-signal circuit jointly ibyits limbs from a substation to an exchange, controlled by the armatures of said line and of a source of current atthe exchange adaptsaid cut-off relays. 7 ed to supply current to the substation-trans- In Witness whereof I hereunto subscribe 5 mitters, aline-relay and one winding ofa difmy name this 5th day of February, A. D. 15

ferenti'al cut-off relay included between one 1903.

terminal of the source of current and the sub- 3 HARRY G. WEBSTER. station, a second winding-0f said differential Witnesses: cut-ofi relay included between the other ter- 1 LYNN A. WIL IAMS,

-10 mjnal of-the source of current and the sub- HARVEY L. HANSON.

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