US741283A

US741283A - Telephone.

Info

Publication number: US741283A
Application number: US12824699A
Authority: US
Inventors: Charles B Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1899-03-06
Filing date: 1899-03-06
Publication date: 1903-10-13
Anticipated expiration: 1920-10-13

Description

PATENTED OCT. 13, 1903.

' L 0 MODEL.

rug NORRIS PETERS 50., WASHINGTON, n. c.

citizen of the United UNlTED STATES Patented October 13,1903.

CHARLES B. SMITH, or NEW YORK, N. Y.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 741,283, dated October 13, 1903.

Application filed March 6 1899 Renewed October 22 1902. Serial No. 128,246.

To all whom zit may concern:

Be it known that 1, CHARLES E. SMITH, a States, residing in New York city, county and State of New York, have invented certain new and useful Improvements in Telephones, of which the following is a specification.

My invention relates more particularly to the class of telephone systems comprising a central oftice and a party-line leading therefrom on which'arelocated a plurality of sub,- scribers stations; and one of the objects of my invention is to enable any subscriber or;-

a party-line to call central and also up prevent onesubscribor from calling at the same time that another is using the line. In carrying out this portion of my invention I pro vide a circuit leading from ground at central through the various stations, and in each station I provide electrical devices arranged so that if the line is clear and closed to ground at central the telephone-receiver-supporting lever in a station can operate when the receiver is removed from the same to close a circuit and produce a call or signal at central, but if the line is broken at central thelever will be prevented from closing such circuit.

Another portion of my invention relates to improved means for enabling an operator at central to call any desired subscriber on a party-line without producing a signal in any other station on a party-line and to establish a circuit in each station in connection with conductors that pass from central to enable a callingrsubscribefls telephone to be connected with such conductors. H

Another object of my invention is to provide an improved plug cord-circuit wherein a battery is bridged across two of the conductors and the primary coils of two inductioncoils are included in said bridge and the secondary coils of such induction-coils are also bridged across said conductors.

The invention further consists in the novel details of improvement hereinafter more fully set forth and then pointed out in the claims. Reference is to be had to the accompanying drawing, which is a diagrammatic view of a telephone system embodying my invention.

In the accompanying drawing the letter A indicates a central office at which are located suitable telephone and circuit-controlling do- (No model.)

connectedbya conductor 11 with ground at 12. Thus in thenormalpositions of these parts I there will be a circuit passing over cond uctor 1 from all the stations to ground 12 at central. This circuit with appropriate electrical de- '-vioes is for the purpose of enabling the lover or' hook 13 of the receiver 14 in each station to establish a circuit for producing a signal at the central office if the line to central is not in use and to prevent such circuit from being established if the-line to central is in use. For these purposes at each station the line 1 is connected by a branch 15 with the lever 13,

is in normal engagement with a contact 10,

which lever has a contact 16, normally out of engagement with but-adapted to engage acon tact 17, that is connected with a conductor 18, on which is located a magnet l 9, the conductor 18 leading to ground 20. The arrangement is such that when the receiver hangs on lever 13 the circuit will be broken at 16 17; but when the receiver is removed from the lever the spring 13 can move said lever to cause engagement of contacts 16 17. To prevent the lever 13 from closing circuit through the receiver if the line 1 is in use, the armature 21 of magnet 19 carries a detent 22, that is adapted to engage and arrest the upward movement of lever 13 if the magnet 19 is not energized. I have shown the armature 21 as passing through an aperture 13 in lever 13, so that the detent 22 in its normal position will lie in the path of lever 13. Thus itthe circuit over line 1 is closed in central at 9 l0 and the subscriber at a station removes receiver 14 from its lever the lever will rise and cause contacts 16 17 to engage, whereupon a circuit will be establishedto central from 2 0 atthe calling-station through 19, 18, 17,16, 15, 1, 4, 6, 7, 8, 9, 10, and 11 to ground at 12. Magnet 19 will now attract armature 21, whereupon detent 22 will be moved out of the path of lever 13 to enable the latter to more the full distance into engagement with a contact 23; but if the circuit over line 1 at central is broken (because the line is in use by some other subscriber or by the operator at central) magnet 19 cannot operate, and therefore detent 22 will remain in the path of lever 13, and thus prevent thelever from engaging contact 23. WVhen, however, the line 1 is closed at central, so that the lever 13 of a calling-subscribers station can make engagement with contact 23, a closed metallic circuit can be established between the calling-station and ventral to produce a call at central as follows: Theconductors 1 and 3 are utilized in forming such closed metallic circuit, and while the line 3 is normally closed from central through all the stations it is adapted to be ,broken into sections in eachstation and the lines 1 and 3 are adapted to be electrically stations.

connected at central and at the subscribers a, contact 24, that is in normal engagement with a contact 25, from which a conductor 26 leads to a contact 4 of jack 5, and a contact 27 in normal engagement with contact 4 is connected by a conductor 28'to a magnet 29, from which a conductor 30leads to conductor 7. The sections of line 3 at each station lead to a movable contact 31, that is in normal engagement-with a contact 32, which is connected by a conductor 33 with the receiver 14 thereat, 34 beluga transmitter, and from receiver 14 a conductor 35 connects with contact 23. The magnet 29 at central has two functions, one of which is to operate contact 9 to break circuit at 9 10 and the other to close a local circuit at central to produce a signal or call. For these purposes I have shown the contact 9 .as carried by but insulated from armature 29, and from said armature a conductor 36 leads through a-battery 37 to a lamp or other signaling instrument 38, from which a conductor v39 leads to a contact 40, adapted to be engaged by armature 29 so that when magnet 29 is energizedcircuit will be broken at 9.10 over line 1 to prevent another subscriber from obtaining a circuit to ground 12 at central and circuit at 29 40 will beclosed to produce a signal in instrument 38 at central.

If asubscriber atthe first station from central on the circuit, as B, desires'to call central, he removes his receiver 14 from lever 13,

which causes contacts 16 17 to engage, and if the line 1 is not in use magnet 19' will operate detent 22 to enable lever 13 to close circuit at 23, whereupon a closed metallic circuit between the calling subscriber and central through magnet 29 will be established as follows: from lever 13 at the callingstation through and over-line 1 to contact 4 at central, thence through 6 7, battery 8 30, magnet 29 28 27 4 26 24, and line 3 to contact 31 at station E, thence through 32 and 33 to receiver 14, thence through 35 and 23 back to lever 13. Magnet 29-will now be energized to break circuit at l0and to close At central the line 3 connects with circuit at 29 to produce a call. If a sub scriber at a station farther along the circuit from central than B had called central, the circuit over line 3 would have passed through station 13. The line 3, as before stated, is adapted to be broken into sections in each station, for which purpose the part of the line 3 that leads into a station from central connects with contact 31, as stated; but the part of line 3 that passes from one station to another, as from B to O, connects with a contact 41, that is in normal engagement with contact 31, thus forming a normally through line in each station at 31 41, (having a branch-or spur extending from 3.2,

thrpugh

33,14, and 35 to contact 23 in each station.) Thus if the subscriber at station 0 had called central the closed metallic circuit before described would have been substantiallyjthe same excepting thatin the intermediater'station B the circuit over line 3 instead of passing to contact 23 at B would have passed from contact 31 to contact 41 and thenceover line 3 to station (3, where it would pass through 32, 33, 14, and 35 to contact 23 and thence to lever 13. The circuit overline 3 will likewise pass through

contacts

41 and 31 at all stations between central and the calling-station. If while a callingsubscriberis producing a call at central another subscriber desires to call central and removes his receiver 14 from its hook, there will be no circuit for his magnet 19, as the circuit is broken at 9 10 at central. -VVhen a call is received, however, theoperator at central in responding places a plug 42 in jack 5, which acts to move contacts 4 and 4 out of engagement with contacts 6 and 27., This of course breaks'the circuit of magnet 29 and allows contacts 9 and 10 to again engage; but as the circuit. over line 1 is now broken at 4 6 another subscriber cannot establish a circuit over line 1 to ground at central for his magnet 19, and therefore cannot produce a call or establish circuit over line 1 while the plug remains in the jack unless permitted so to do by the operator at central. I

The contacts 42 oftwo plugs 42 are conn'ected by a conductor 44, and the contacts 42 are connected by a conductor 49. The contact 42 is adapted to engage contact 4 in jack 5 to break circuit at 4 6, and the'contact,

42 is adapted to engage contact 4 of jack 5 to break circuit at 4 27. The

conductors

44 and 49 contain in abridge a battery 45 and the primaries of two repeating or induction coils 46, one on each side of the battery, and the secondary coils 46 are bridged across conductors 44 49 independently of the battery 45, as by conductors, preferably leading to a condenser 46". is adapted to be bridged across conductors 44 49 by means of a push button or key 47, acting to press a contact 47 into engagement with a contact 47 connected with conductor 44, and a spring 48 into engagement with a contact 48, connected with conductor 49, the

The receiving-telephone 43 springs 47 48 being connected with receiver 43. When the plug is in the jack, the battery 45 and the repeating-coils are connected with lines 1 and 3 for the telephone instruments. .The induction-coils shown have a corle and are adapted to be used as impedancecm s.

Suppose the operator at station calls central. In response the operator at central places plug 42 in jack 5 and'operates key 47. A closed metallic circuit between the calling subscriber and central will thus be established as follows: from lever 13 at G through 15 to line 1, thence to 4 at central through 42 44 and through receiver 43 to 49, thence through 42*, 4, 26, 25, and 24 to line 3, thence over line 3 (through

contacts

31 and 41 at B) to 31 at O, thence through 32 and 33 to receiver 14, and through 35 and contact 23 back to lever 13 at G. The battery supplies current for the circuit, and the fluctuations of the current through coils 46 induce current in coils 46, which traveling over the circuit produces the effect of an induced current in the receiving-telephones. It will be seen that this induced current passes to the circuit inpendently of battery 45. The condenser 46 in the circuit of the secondary coils 46 prevents the leakage of current from battery 45 through the secondary coils. After the operator at central ascertains what subscriber is wanted he.is to call'such subscriber.

The arrangements I have shown for enabling the operator at central to call the desired subscriber without calling any other subscriber on the circuit are as follows: The line '2, which I term an operating-line, is utilized for establishing a circuit in the desired subscribers station for a si nalin instrument thereat in connection with line 1, over which a call is produced. tion a suitable signaling instrument is connected with line 1.5, and line 15 leads to a contact 56. The contact 56 is normally out of engagement with but is adapted to be engaged by a contact 57, that is normally out of engagement, but adapted to engage a contact 58, connected by a conductor 59 with ground at in each station, so that when'contact 57 engages contacts 56 58 the circuit in the station for the signaling instrument 55 will be from line 1 through 15, 55, 56, 57, 58, and 59 to ground 60. The contact 57 is to be operated by current on line 2. The line 2 is not normally closed through the subscribers stations, but is broken into sections in said stations adapted to be connected into a throughline, for which purpose the part of the line 2 that leads into a station from central is shown connected with a contact or armature 61, that is in normal engagementwith acoutact 62, connected by a conductor-63 with ground, being shown connectedwith conductor 59 and thence to ground 60. 64 is a magnet in each station located on the part of line 2 that leads into the station, which magnet is shown having poles at both ends, one

At each sta-' 14 at B is broken at 32 31.

of which is adapted to attract armature 61, (which is a dead armature having no spring,) and the other pole is adapted "to attract an armature 65, that is connected with but insulated from contact 57, so as to operate the latter, and provided with a spring 66, that acts to normally hold contacts 56, 57', and 58 out of engagement. The armatures or

contacts

61 and 65 are shown connected by a in a station is also connected with'a contact 68, that is on the side of the magnet toward central and adapted to be engaged by contact or armature 61 when magnet 64 is energized. The section of line 2 that leads from a station is in the station from which it leads connected with a contact 69, that'is in normal engagement with armature or contact 65. The

parts

61, 68, 67, 65, and 69 are for the purpose of joining two sections of line 2 together in a station to establish a throughline out of such sections.

If the operator at central desires to call the first station on a circuit, as B, he sends an impulse over line 2,which passes through magnet 64 at B and thence through 62, 63, and 59 to ground 60. Magnet 64 thereupon draws

armatures

61 and 65, breaking .circuits' at 61 62 and at 31 32 41 and closing circuit at 61 68, and armature 65 breaks circuit at 69 and closes circuit at 2 56 57 58. Thereupon a temporary ground for the first section of line 2 will be established at B'from 2 through 2, 57, 58, and 56 to 60 to keep magnet 64- energized to hold a circuit for the calling instrument 55 closed at 56 57 58. The operator at central then sends an impulse over line 1, which passes through 15, 55, 56, 57, 58, and 59 to ground 60 at B, producing acall. The operator next breaks the current from line 2, and the spring66 causesarmature 65 to return, thereupon closing circuit at 65 69 and breaking circuit at 56 57 58. Two sections of line 2 at station B w'ill now be joined together from the part of line 2 leading into the station through 68, 61, 67, 65, and 69 to the next section of line 21eading from station E. It will be observed that the circuit of line 3 is still broken in station E at 31 4i and that the circuit for receiver It will be therefore necessary for the operator at central to restore circuit at 31 32 41, as will be hereinafter explained. desired to call station C instead of B, he would have sent one impulse over line 2 to station E, as before described; but before sending current over line 1 he would break the impulse over line 2, whereupon two sections of line 2 at B would be joined together, as described, and he would thereupon send another impulse over line 2, which would If the operator at central had ICC pass through station B to ground 60 at station 0, whereupon magnet 64 at ,Owould'

attractarmatures

61 and 65, breaking circuit at 61 62 and establishing the temporaryground at 67.58 to keep magnet 64 energized and closing the circuit of the signaling instruinent 55 at 56 57. Thereupon current will upon the current will flow on over line 3, per-' be sent over line 1,which will pass to ground at station 0, (not passing to ground 60 at station B because of the break in the circuit at 56 57,) and he will thereupon discontinue the current on line 2, whereupon spring 66 will move armature to close circuit at 6569 and break circuit at 56 57 58. So, also, if there are more stations than one on the circuit between central and the sta-- tion to. be called an impulse will be sent over line 2 for each station to and including the station desired, whereupon in each intermediate station the sections of line 2 will be joined into a through-line to ground 60 at the station desired. The next step is to restore armature or armatures 61 to .normal position to reestablish circuit at 61 62 and'at 31 32 41, the arrangements for which are as follows: At each station is a contact 70, that that have been operated, the operator at central sends a prolonged impulse over line 3, which passes through 31 70, 71*, and 72 to ground 73 at the first station from central, whereupon that magnet attracts armature 61, which breaks circuit at 61 68 and 31 and closes circuit at 61 62 and at 31 32 41, whereforming the sameoperations in each station in which the devices have been operated in reaching the station to be called, so that .the calling subscriber will have a circuit for the receiver in his station from 13 through 23, 35, 14, 33, 32, and 31 to line 3. When the calledsubscriber removes his receiver from its le ver, the latter would be prevented from engaging contact 23, caused by the presence of plug 42 in jack 5; but to form a ground at central for magnet 19 at the called station over line 1 the operator at central presses key 47 to close circuit at 47 47 and move contact 48 into engagement with a contact 52, that leads by a conductor 53'to ground, as at 54, and also into engagement with'con'tact 48, connected with conductor 49, whereupon a circuit from the called station over line 1 to ground at central wil} be established as follows: from 20 at the ca 19 18 17 16 15 to line 1, thence to contact 4 and through 42 44 and battery 45 to 49, thence through 48 48, 52, and 53 to ground 54. Magnet 19 at the called station will now led station through attract its armature2l and cause detent 22 to allow lever 13 to engage contact 23. If the calling andcalled subscribers are on the same party-line, their receivers 14 will now be in a closed metallic circuit established as follows: from lever 13 at station B through 23, 35, 14, 33, 32, 31, and 41 thereat to line 3, thence to contact 31 at station 0 through 31,

32, 33, 14, 35, 23, lever 13, and conductor 15 to line 1, thence over line 1 to conductor 15 at B and back to lever 13. The telephones for stationsB and G will now be in multiple. The battery at 45., located at central, supplies current for the transmitters, as heretofore described. If there are any stations on a circuit between the calling and the called subscribers, the circuit will pass through such intermediate stations unbroken over line 1 and through

contacts

31 and 41 of line 3. -If the calling subscriber is on a different cir-. cuit from the called subscriber, the operator at central may connect the jacks 5 of such two-circuits, and the arrangement is such that the battery 45 will operate on both circnits.

It will be, understood that a party-line organized as described can be utilized with other similar party-lines or other Well-known telephone-circuits leading to a jack at central.

Any suitable means may be provided to notify the operator at central to disconnect the lines, such as magnet a on the plug-cord circuit adapted to close a localcircuit b of a.

lamp orother signalinginstrument 0. While a subscribers telephone is connected with conductors 1 3 the lamp 0 will glow; but as soon as a subscriber hangs his receiver upon lever 13, and thus breaks circuit at 13 23, magnet a will be denergized and the light will go out, thus indicating to the operator at central that the subscriber has finished.

using the line.

Any suitable means can be provided at cen tral for-se'ndin g the appropriate impulses over the lines 1 2 3 to select and call the desired station. The devices I have shown for the purpose are as follows:

At central is a toothed wheel 75, whose shaft 76 may be suitably journaled and provided with a handle 77, and 78 is an annular contact carried by insulation 79, attached to said wheel. The wheel has a long tooth 75 and a series of shorter teeth 75 upon its periphery.

'80 is a contact suitably supported and in engagement with contact 78 and connected by a conductor 81 with a battery 82, from which a conductor 83 extends to ground 84. The contact 78 is connected by a conductor 85 with a movable contact or switch 86, pivotally carried upon the insulation 79 or otherwise insulated from butcarried by wheel 75.

87 is a contact carried by wheel 75 and adapted to be engaged by contact 86, the contact 87 being in electrical connection with a and 96 engage.

90 is a stop carried by insulation 79 or otherwise carried by and insulated from wheel 75, which is adapted to be engaged by the 1 con tact S6.

The contact or switch 86 is adapted to be moved into engagement with contact 87 and stop 90 during the rotations of wheel 75. For this purpose there is a stop or pin 91 located at the slartingpoint, with which switch 86 comes into engagement when wheel returns to the starting or home point, whereby switch 86 will be moved into engagement with stop 90, which is the normal position of the parts. To cause switch 86 to engage contact 87, I

provide a plug 92, which is adapted to he in serted in apertures 93 in a plate or ring 94,

forming part of the mechanism. The apertures 93 are at suitable distances apart, and each one corresponds to a station on a partyline, and when the plug 92 is in one of these apertures and wheel 75 is rotated the switch 86 will engage such plug and will thereby be moved into engagement with contact 87, and the rotation of wheel 75 will be stopped. By preference I-provide insulation 86 on switch 86 to engage the plug 92.

The teeth upon wheel 75 are adapted to make and break circuit through the operatiug-line 2, and for this purpose I have shown a contact 95 connected with line 2 and a contact 96 'onnected with conductor 88, which contacts are adapted to make and break circuit under the influence of the teeth of wheel 75. I have shown a rocker-arm 97 pivoted at 98 and adapted to be operated by the teeth 75 75" of wheel 75 to make and break circuit between the

contacts

95 and 96, insulation 97 being provided between 96 and 97. When switch 86 engages contact 87, the circuit for line 2 at central will be from ground84, through 83, battery 82 81 78 86 87 and wheel 75 to contact 88, thence to conductor 88 and through 96 and to line 2, when 95 The impulse for the calling-circuit from central to-the subscribers stations is also controlled through the medium of wheel 75, for which purpose I have shown a conductor 99, leading from the conductor 1 to a contact 100, and 101 is a contact to make and break circuit with contact 100.- Contact 101 is connected by a conductor 102 with a generator 103 (which may be a power-generator,) from which a conductor 104 leads to ground, being shown connected with conductor 83. 105 is a rocker-arm pivoted at 106 and adapted to operate contacts 101, insulation being provided hetwpenlOO and 105. 107 is a projection carried by wheel 75 and adapted to operate rocker-arm 105, projection 107 being shown at one side of tooth 75 of wheel 75; but tooth 75 extends beyond projection 107. The arrangement is such that tooth 75 and projection 107 will cause rocker-arms 97 and 105 to simultaneously close the circuit at 95 96 and v at 100 101, and when projection 107 passes from rocker-arm 105 circuit through 100 101 and when wheel 75 moves 'in the reverse di-' rection (which may be by hand, clockwork, or otherwise) the teeth upon said wheel will operate rocker-arm 97 to cause the desired number of impulses to pass over line 2 and establish a circuit for the signaling instrument in the station desired, as before described, and when projection 107 reaches rocker-arm 105 tooth 75 will still hold the circuit closed at 95 96 of the opposing line 2, during which time a signal will be produced in the desired station orera circuit, as follows: from ground 84, through 83 104, generator 103, 102, 101, 100, (101 and 100' being new in engagement,) and 99 to line 1, thence to the station to be called-say C.-thence through 15, signaling instrument 55, 56, 57, 58, (which are now held in engagement by current on line 2,) and 59 to ground 60, thus producing a call at the desired station. Projection 107 will next move from arm 105 to break the calling-circuit, and thereafter tooth 75 will move from arm 97 to break the operatingcircuit. The circuit, over line 3 to restore the subscriber-selecting devices to their normal condition is also controlled by the action of wheel 75, and the arrangement for this purpose is as follows: The line 3 at cen tral is connected, as by a conductor 108, with a contact 109, that is normally out ofengagement with but adapted to engage a contact 110, and 111 is a rocker-armadapted to make and break circuit between contactsl09 110, and wheel 75 carries a projection 112, adapted to rock the arm 111, insulation'being interposed between arm 111 and contacts 109. The arrangement is such that after tooth 75 and projection 107 have moved away from rocker-arms 97 and 105, respectively, as wheel 75 passes toward the home-point the projection 112 will operate arm 111 to close the circuit at 109 of the i'esto|'ing-line, whereupon the circuit will be from ground 84 through 83, battery 82 81 80 78 85 86 87 (86 87 being still in engagement) to 88 88, 110, 109, and 108 to line 3 and thence to the subscribers stations to restore the operated devices thereat, as before explained.

In order that there shall be no circuit from line 3 through contact-s 24 and 25 and conductor 26 of jack 5 while a station is being called, I have provided a rocker-arm 113, shown pivoted at 114 and adapted to make and break circuit between contacts 24 25, a projection 115 being carried by wheel 75 to operate said rocker-arm, and the position of this projection is such that when wheel 75 has been moved from the home-point said projection will move away from arm 113, and

IIO

understood that when wheel 75 is moved fromthe home pointcircuit at 24 25 will first be broken and that the projections 107 112 and the appropriate teeth of the wheel will pass under the rocker-arms,.and that when the wheelis returned -to the home point animpulse or impulses will first be sent over the operating-line 2 to operate the selecting devices of the subscribers stations to close the circuit of the signaling instrument thereat with line 1, that when the circuit of said signaling instrument has been so established the proper impulse will be sent over line 1 to operate thesame, that thereafter an impulse will be sent over the restoring-line 3 to restore the operating devices at the stations to their normal conditions and break, the circuit of the selected signaling instrument, and that thereupon switch 86 will engage stop 91 to break circuit at 8687, and projection 115 will come to rest under arm 113 to restore the circuit at 2 1 25. It will also beunderstood that a tooth on wheel 75 corresponds to each station on a party-line and that for each tooth that passes under rocker-arm 97 an impulse will be sent over the party-line 2. For instance, if the first station on a party-line is to be called, plug 92 will be inserted in the appropriate hole 93 and the wheel turned until switch 86 engages said plug and is'moved into engagement with contact 87, and tooth 75 will pass under arm97,'so that as the Wheel returns to the home point one impulse will be sent over line 2 to close the circuit of signaling instrument 25 thereat. O (the secondstation on' the party-line) is to be called, plug 92 will be placed in the appropriate hole 93 and wheel 75 can turn. until tooth 75 and the next tooth 75" pass under rocker-arm 97, and so on for as many stations as there are on a party-line between the central office and the station to'be called, including the latter station.

I do notlimit my invention to the precise details of construction shown and described, asthey m ay be varied without departing from the spirit thereof. For instance, a returnwire can be used in place 'of the grounds shown.

Having now described my invention, what I claim is.-

1. A telephone system comprising a central office, a plurality ofsubscribers stations, a conductor leading from central to said stations, telephone instruments in each station,

and electrically-operating devices in each station for connection with said conductor and arranged to permit the supporting-lever of the receiver to establish a circuit for the latter if the circuit over said conductor is closed and to prevent the lever from establishing such circuit for the receiver if the circuit is broken, a second conductor leading from central for said stations, means at the stations to connect saidconductors, and means at central to be operated when the circuit of said' conductors is closed to break the circuit of the first-mentioned conductor.

2. A telephone system comprising a central oftice, a plurality of subscribers stations, a

conductor leading from central to said Sta t-ions, telephone instruments in said stations, electrically-operating devices in each station normally-out of circuitv with said conductor but adapted ,to be placed in circuit therewith by the movement of the receiver-supporting lever, said devices being arranged to permit full movement of said lever when the circuit over said conductor is'closed at central and to prevent such movement of thelever if said circuit is broken at central, a second conductor leading from central for said stations, means at the stations to connect said conductors, and means at centralto be operated when the circuit of said conductors is closed to break ,the circuit of the first-mentioned conductor.

3. A telephone system comprising a central oflice, anplurality of subscribers stations, a conductor leading'from central to said stations, Ltelephone instruments in said stations, electrically'operatin g devices in said stations located on a normally open branch line leading from said conductor, means to close the branch line by themovementof the receiversupporting lever, said electrically-operating devices being arranged to permit the full movement of said lever when the circuit over said conductor is closed at central and to prevent such movement of said lever when said :circuit is broken at central,-a second conduc- If station" tor leading from central for said stations,

means at the stations to connect said conductors, and means at central to be operated when the circuit of said conductors is closed to break the circuit of the first-mentioned conductor.

4. A telephone system comprisinga central office, a plurality of subscribers stations, a

conductor. leading from central to said stations, telephone instruments in said stations, a normally open branch line in each station leading from said conductor, a contact to be operated by the receiver-supporting lever to makeand break the circuit of the branch line, and electrically-operatingdevices connected with said branch-line arranged to permit-the full movement of said lever when the circuit over said conductor is closed at central and to prevent such movement of said lever if said circuit is broken at central, a second conduc- -t or leading from central for said stations, means at the stations to connect said conducraises tors, and means at central to be operated when the circuit ot'said conductors is closed to break the circuit of the first-mentioned conductor.

5. In a telephone system a central oilice, a plurality ofsubscribers stations, a conductor leading from central to said stations, telephone instruments in said stations, a normally open branch line in each station learling from said conductor, a contact to be'operated by the receiver-supporting lever to make and break the circuit of the branch line, a magnet located on each branch line, a detent to be operated by 'said magnet, said detent in its normal position serving to check the full movement of said lever, and a contact tobe engaged by said lever to close the circuit of the branch line, whereby when the circuit of said conductor is closed at central said magnet will operate the detent to permit the lever to make a full movement and when the circuit is broken at central said detent will prevent the lever from makinga full movement, a second conductor leading from central forsaid stations, means at the stations to connect said conductors, and means at central to be operated when the circuit of said conductors is closed to break the circuit of the first-mentioned conductor.

6. A telephone system comprising a central office, a plurality of subscribers stations, a plurality of conductors leading from central to said stations and normally connected'at central, one of said conductors being normally connected to ground at central, electrically-operating devices connected therewith at central arranged tobr'eak said ground, and devices at each station to join said conductors thereat in a closed metallic circuit, and arranged to preventthe formation ofsuch closed metallic circuit when the ground at central is broken.

7. A telephone system comprising a central ofiice, a plurality of subscribers stations, a plurality of conductors leading from central to said stations and normally connected together at central, one of said conductors being normally cpnnected to ground at central, electrically-operatingdevicesconnectedtherewith at central arranged to break said ground, other contacts at central connected with said conductors to be broken by the operator at central, devices at each station to join said conductors in a closed metallic circuit, and arranged to prevent the formation of such closed metallic circuit when the circuit at central is broken.

8. A telephone system comprising a central oifice, a plurality of subscribers stations, a plurality of conductors leading from central to said stations and normally connected together at central, one of said conductors being normally connected to ground at central, electrically operating devices connected therewith at central arranged to break such ground, other contacts at central connected with said conductors to be broken by the operator at central, devices at each station to 'at to break the join said conductors thereat in a closed metallio circuit, said devices being arranged to prevent the formation of a closed metallic circuit when the circuit at central is broken, and means at central to produce a call when the circuit between central and a station is closed.

9. A telephone system comprising a central office, a plurality of subscribers stations, a pair of cond uctors leading from central to said stationsand normally connected at central, one of said conductors being connected-to ground at central, electrically-operating devices at central connected with said conductors and adapted to break said ground, callproducing instruments at central adapted to be operated by current on said conductors, means at central to enable the operator therecircuit to ground, telephone instruments in said stations, means for joining said conductors in a closed metallic circuit through said telephone instruments, and electrically-operating devices in each station adapted to prevent the formation of said closed metallic circuit when the ground at central is broken.

10. Atelephone system comprisingacentral office, a plurality of subscribers stations, a plurality of conductors leading from central to said stations, one of saidconductors being connected to ground at central, contacts at central to. make and breakthe circuit to ground, a magnet and armature at central connected to said conductors adapted to make and break said ground,telephone instruments at said stations, means at said stations to join the telephone instruments in a closed metallic circuit over said conductors, whereby when said circuit is closed the magnet at central will break the ground, and means in said stations to prevent the closed metablic circuit frem being established when said ground is broken.

11. A telephonesystem comprisinga central oifice, a plurality of subscribers stations, a

pair of conductors normally connected at cen-' tral and leading to said stations, one of said conductors being connected to ground at central, contacts tomake and break said ground,

a local circuit at central having devices to produce a signal,'a magnet connected. with said conductors at central adapted to break said ground and close said local circuit, telephone" instruments in said stations, means to connect them with said conductors ina closed. metallic circuit whereby when they are so con nect'ed a signal will be produced at central, and electrically-operating devices in said stations to preventsaid closed metallic circuit from being established when the ground at central is broken.

12. Atelephonesystem comprisingacentral oftice, a plurality of subscribers stations, a plurality of conductors normally connected at central and leading to said stations, one of said conductors being connected to ground at central, means at central to make and br ak said ground, a jack at central connect-.

each station, a magnet on the section thatleads into a station, said magnet having two -poles,-an armature for each pole, a normally open branch in each station from one of said conductors adapted to .be closed to ground by a contact operated by one of said armatures,

abranch leading to the telephone instruments in each station from a contact adapted to be operated by the other armature to break the circuit, said contact being connected in each station with another of said conductors, said armatures being connected together and contacts to cause two sections of the first-mentioned circuitto be joined in a station by the operation of said armatures.

14. A telephone system comprising a plurality of stations, a plurality of conductors leading to said stations, one of said conductors being normally broken into sections in said stations, a magnet in each station connected with the section that leads into the station, said magnet having two poles, armatures to be operated by said poles and contacts to be operated by said armatures, another of said conductors being normally closed through contacts in said stations, said armatures beingarranged to join two sections of the first-mentioned circuit together and break the second-mentioned circuit into sections, a magnet in each station, and devices operated by one of said armatures. for connecting said magnet with the section of the second-men'- tioned circuit that is formed by the first operation of the armature, whereby when said magnet isoperated it will restore the parts to their normal conditions.

15. A telephone system comprising a plurality otstations, a plurality of conductors leading to said stations, one of said conductors being broken into normal sections leading to ground in said stations, a magnet on the section that leadsintoastation,said magnets each having two' poles and a pair of armatures one of which is adaptedjto break the ground from the sect-ion and make connection with the conductor opposite the ground, one armature being in normal connection with the section of the conductor leading from the station, said armature having a contact normally connected with the section. leading into the station and adapted to establish a temporary ground in said section to be broken when the magnetis deenergized, another conductor being normally closed in each station and having contacts adapted to be made and broken by one of said armatures, and a magnet for said armature arranged to be placed in circuit with the section of said conductor leading into a station by theinitial action of said armature, said magnet being arranged to attract said armature to restore the through-circuit of said conductor.

CII AS. B. SMITH.

\Vitnesses:

F. E. TURNER, T. F. BOURNE.

on the side of the magnet