US816132A - Telephone system. - Google Patents

Description

PATBNTED MAR. 2'?, 1906.

G. B. SMITH. TELEPHONE SYSTEM.

Puentes Hum nov. sa. lags. nmswnn oo'r. z2. m2.

Swimming@ mq ttoznu @fg/@1MM 'Y PATENTED MAR. 27, 1906 G. B. SMITH, TBLBPHGNB SYSTEM.

APPLXGATIOX FILED NGV. 2S, 1BRS. BBNEWBD 00T. 22, 1992.

2 SHEETS-SHEET 2.

xxxxx xr umm CHARLES B. SMITH, OF NEW YRK, Y.

TELEPHONE SYSTEM.

Specification of Letters Patent.

r'atented March 27, 1906.

applicati@ le November 28, 1898. Renewed October 22, 1903. Serial No. 128.244.

To @ZZ whom it may concern:

Be it known that I, CHARLES B. SMITH, a citizen of the United States residing in New York city, county and State' of New York, have vnvented certain new and useful lmproverncnts in Telephone and Calli'ng Systems, of which the following 1's a specifica'- tion.

My invention relates more particularly to the class of telephone and calling systems in which is embraced a central ollice and circuits leadin therefrom, which are commonly known as party-lines and on, which cir cuits are located a plurality of subscribers or stations; and one of the objects of my .nvena tion is to provide party-line circuits on which ani.T subscriber can call central and central can call any subscriber or station without producing a call in any other station. ln carrying out this portion of my invention l provide improved circuit-chang-ng devices at a central olice, from which extend conductors, With certain of which conductors are connected in each station suitable telephone and calling instruments to enable a subsciber to call central and to connnunfcatc telephoncally therewith and with any other subscriber or station on the saine circuit o; any other circuit, and with certain other of said conductors at each station are connected means for Inak'ng and breaking a calling-circuit, which means are controlled and oper ated at the central office by the first-mentloned improved circuit-changing dev'ces to enable central to call any subscriber or stati'on as desired Without signal' ng in any otherI station on the same crcu t. Suitable means are provided at central to enable one pal-tylne to be connected with the other circuits leading into the central ollice.

A further object of the invention is to so afrange the telephone-climat that when two telephone instruments are fn telephone conirnun catfon another subscriber cannot interfere or produce a call in the stat'ons that are so connected.

The nventon also-consi' sts in the novel detals of improvement that w` ll be more fully hereinafter set forth and then pointed out in the cla'rns.

Reference is to be had to the accompanyn d;awi'ngs, fo m'ng part hereof, wherein*- .gu'ge 1 "s a d ag arnmat'c v 'ew of a telephone and calln system embody'n my iinventon, the loca circuits for the te ephones be'ng omitted for the sake of clearness. Fig.

2 is an enlarged sect'onal view of part of the circuit-chan ng device at the central office. Fig. 3 is'n a retail face vfew of art thereof. Fig. i ie a plan view, enlarge of the improved circuVt-changfng dev ces et central; and Ff. 5 is a secti'on on the line V5 5 in Fi 4.

In the accompanying drawings, in W 'ch similar letters and numerals of reference indicate corresponding parte in the several views, l, 2, and 3 indicate conductors or wires forming the circuits for a party-line which leads from a central oihceA and on which party-line are a plurality of stations, as B C, having appropriate telephone, calling, and circuit regulating or changing devices. At central A the line 1s shown provided With a suitable or usual drop or annunciator 11 and a springjack 5 to enable the o erator thereat to connect his telephone 6 y means of a plug 7 with line 1 in Well-known manner. The jack 5 also serves to enable the o erator at central to connect one'subscribers ine with another (not shown) in well-known manner. At central A the line 1 connects with a contact l, and 2 is a contact for electrical connection with line 2, the contacts la Zabeing adapted to be electrically connected for certain purposes hereinafter explained. At central A are located an electro generator or magneto 8 'and a normally open push-button or switch 9,-Which connects with ground 10 and with a conductor l1 that leads to line 1. The connecton of conductor 11 with line 1 is between the annunci'ator or drop 4 and the outlying stations B C, so that when generator 8 is op erated at central to call a station on the corresponding circuit the annuncator 4 connccted with said circuit will not be operated.

At each station B C, Sec., on the party-line circuit suitable telephone instruments (indcated generally by the letter B) are located and proberly connected with the line 1. I have shown the line 1 as normally closed through a contact lever or hook 12 when the receiver D is hun upon it, the circuit through line 1 in eac station being arranged to be broken and restablished in several Ways for purposes to be explamed. The normal arrangement ol the clrcult through line 1 in each station is shown as follows: Line 1 between central and the various etations is divided or made in sections, each division or section leading to a contact 13 that is normally engaged b a switch or contact 14, whfch :le connected y a conductor 15 and a contact 16 with hook 12 when the receiver IDU IOS

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D is hung upon the latter. Thus when switch 14 is moved from contact 13 the circuit just described wll be broken. The receive;l D is connected wfth l'ne 1 by a conductor 17 and by a conductor 18 with a contact 19, that is normally out of engagement with hook or lever 12, but adapted to be engaged thereby when the rece. ver is removed rom the hook foil telephonie purposes.

Line 1 is ut l Zed foil enabling a subscrfbe.' or attendant at stations B C, &e., to call centralas follows: In each station a conductorl 20 is connected with line 1 and leads through a signaling instrument 21 to an electric enerator or magneto 22, from which a con uctor 23 leads through a normally open pushbutton or contacts 24 to ground 25. Now if a subscriber at station B desires to call central he first closes the circuit at 24 and operates his generator 22. His calling-circuit will then be established as follows: from ground 25 through 24, 23, 22, 21, and 20 toY line 1, thence through the annunciator 4 and jack 5 (at central) to contact 1a, and thence to contact 2rL through a contact E, which at this time connects 1a and 2t, (as will be explained hereinafter,) thence through a wire 2b, switch 2C, contact 2, and wire 2e to ground 26. lf a subscriber at station C desires to call central, his calling-circuit will be as follows: from 25 through 24, 23, 22, 21, and 2() to line 1 in his station, thence along line 1 to hook 12 at station B, thence through 16, 15, 14, and 13 to line 1 at B, and thence along line 1 to ground 26 at central, as before explained. So also with any stations on the circuit beyond C the circuit through each intermediate station will bc through its respective parts 12, 16, 15, 14, and 13. The l`ne 1 not only serves as a calling-circuit from the subscribers to central, but also as a part of a closed metallic telephoning-circut, as will be 4explained hereinafter.

The complete calling-circuit from central to each of the stations on a party-line is as 4 follows: from ground 1() tln'oughiparts 9, 8,

and 11 to line 1, thence (at the rst station next to central, as B,) through conductor 2() and instrument 21 to a conductor 27, which leads from 20 or 21, and thence to ground 28 at said station, but the circuit through 27 to ground 28 is normally broken and must be closed by the operator at central before the corresponding calling instrument 21 can be operated, as hereinafter ex lained. The circuit through 27 to groun 28 is made and broken as follows: Conductor 27 leads to a movable contact 29, (operated as hereinafter explained,) which is adapted to engage a contact 30, that connects by a conductor 3] with ground 28, so that the complete closed circuit from 20 and 21 to ground 28 is through 27, 29, 30, and 31. When central is to call any station beyond B, as C, the calling-circuit will be from 10, through 9, 8, and 11 to line 1, thence to wire 20 at B and through 13, 14, 15, 16, and 12 to line 1, thence to 20 at C and through 21, 27, 29, 30, (after 29 and 30 have been brought together,) and 31 to ground 28. Thus it will be seen that when an operator at a station, as C, calls central thc signaling instruments 21 in the other station or stations will not be operated.

To enable central to produce a call only in the station desired, the circuit through 27 to ground 28 in the station must be closed and held closed at 29 30 while a call is heilig sent, and the corresponding circuits through 27 to ground 28 in the other stations on the partyline must be kept broken at that time to prevent a call from being produced thereat. The arrangements l have shown for this purpose are as follows: In each station the line 3 is normally broken, or, in other words, is divided into sections, which lead from one station to another and are capable of being joined together in each station. Each section of line 3 is normally grounded in one station and normally open in the station from which it leads, or, in other words, the first section of line 3 leads from central normally to ground in the first outlying station, as B. The next section leads from B to normal ground at the next station, and so on for as many stations as are on a circuit. For this purpose I have shown each section of line 3 in` each station as leading to a contact 32, that is in norlnal engagement with a movable contact 33, that leads to ground, as by a wire 34, connecting with wire 31 and thence to ground 28. At central the corresponding section of line 3 leads to a circuit-controlling device-such as a switchboard, key, or pushbutton; but at the stations the corresponding section of line 3 leads from a movable contact 35 to ground at the next station. The contacts 33 35 are shown connected together, so as to move simultaneouslyv but they are insulated from each other, as by insulation 35a.

ln each station on the corresponding section of line 3 is located a magnet 36, whose armature 37 is arranged to operate contact 29 to close the circuit through 27 to ground 28, contact 29 being insulated from armature 37, as by insulation 29a. Each armature 37 is connected by a conductor 38 with the corresponding section of line 3, and the same section of line 3 beyond magnet 36 is connected with a contact 39, as by a spurwire 40. Armature 37 (or a contact carried thereby and connected with wire 38) is normally in connection with a contact 41, that connects by aconductor 42 with a contact 43, normally out of engagement with contact 35, but adapted to be engaged thereby. tacts 33 and 35 are adapted to be moved through the medium of armature 37 to break circuit at 32 33 and to electricall connect two sections of line 3 at 35 43, t e circuit thus being from one` section of line 3 through IOO LU i

33, 3.7, 4l, 42, 43, and 35 to the next section of line 3. I have shown contact 29 as adapted to en age an arm 44, connected with con tact 33, parts 33 44 being pivotally supported and adapted to remain 1n any position set,) so that when armature 37 is attracted by magnet 36 the contacts 33 35 will be moved to break circuit at 32 33 and to make cirenit at 35 43, respectively.

With the arrangement above describedV if"Y central desires to call the first station on a party-line, as B, he first sends current over ine 3 (by means hereinafter set forth) which .traverses the Erst section of line 3, through magnet 36 to ground 28, as before explained, whereupon magnet 36 attracts armature 37. Thereupon contact 29 engages contact 39 and also engages contact 30, thus establishin the calling-circuit through 27, 29, 30, an( 31 to ound 28 for calling instrument 2l (all at station 13,) While at the same time arm 44 moves contacts 33 and 35 to break circuit at 32 33 and establish circuit at 35 43. Of course the disengagement of contacts 32 33 breaks the normal ground of the section of line 3 g but a temporary ground is established from 3 through 40, 39, 29, 3i), and 31 to ground 28, keeping magnet 36 energized to hold contact at 39 29 30. The operator thereupon sends a call to station B over the circuit so selected from ground ll) through 9, 8, 11, and 1 to conductor 23 at B, thence throu h 21, 27, 29, 3U, and 31 to ground 23, (a l at B.) By next discontinuing the circuit through 3 and 36 to ground 28 the armature 37 is restored to its normal position by its sprin r 37a, thus breaking the circuits at 30 and 39 ut the circuit through 43 35 still remains closed. (The manner of restoring the Contact 35 to its normal position will be explained hereinafter.) Should the operator at central have desired to call station C instead of B, he would have sent an impulse over line 3 to B, as just explained, to cause armature 37 to bring contacts 43 35 together. Then he would break the current thus sent to cut the ground 28 from the circuits through 36 27, &c., to out out the bell at that station and restore armature 37 to its normal position, and the next impulse he would send would ass along line 3 to 33 at B, thence througllj37, 41, 42, 43, and 35 to the section of line 3 leading from B to C, thence at C through magnet 36 to 32, 33, 34, and 31 to ground 28 at C. Magnet 36 at C will now cause armature 37 to close the temporary groundwcircuit at 2.() 39 and the bell-circuit at 29 30 and to break circuit at 32 33 and establish circuit at 35 43 to the next station beyond, (if there be one,) whereby the bell at C is brought into circuit and so held until operated by current sent from central over line l, as before explained. Thus it will be seen that for each 1m ulse sent by central over line 3, ctc., the ca ling-circuit through 27 will be closed and the sections of the line 3 con-V nected in a station and that the closing and breaking of these calling-circuits in the stations are successive until the circuit of the desired bell is reached. Thereby only the boli or si naling instrument in the station desired Wil he in circuit at one time, as itis not possible to have circuits in two Vstations through 27 closed at one time. Any suitable ineensnemK7 be provided for sending the desired impulses over line 3 g but I have shown a special arrangement for erformin this and other functions which Wi l be described hereinciter.

It now remains to oe explainedhow the contacts 33 and 35 are restored to their normal positions, how a closed metallic circuit is established for the telephones, and the means I have shown for enabling the oper ator at central to perform all the operations required.

At the central station A the line 2 is connected with a Contact 2f, that is adapted to be engaged bysn-itch 2, and in each station the line 2 is divided or arranged in normallT connected sections-that is to say, the line is provided with a movable Contact 45, connected'to one part, and a stationartV7 contact 46, connected to the other part, which contacts are normally engaged but adapted to be disengaged. Contact 45 is shown mechanieally connected with the corresponding contact 35, but insulated therefrom, as byinsulation 45a, and arranged to be moved therewith, or, in other words, contacts 33, 35, and 45 are so connected as 'to move together. Each contact 45 is shown in the nature of an armature, {or it may have an armature Connected with it,) adapted to be attracted by a magnet 47 in each station, and each magnet 4? is connected with a conductor 48, that leads from the part of line 2 that is between Vthe corres ending contact 45 and the station next on t e line nearest central, and each conductor 48 leads to a contact 49, that is adapted to be engaged by the corresponding Contact 33 when the latter is actuated through the medium of magnet 36. lt will thus be seen that when contacts 4.5 and 46 in any station are not in circuit contacts 4Q and 33 are in circuit and the corres ending part of ll ne 2 next toward central W l be grounded from 2, through 48, magnet 47, Wire 49, 33, 34, and 3l to 'round 28. Now if the operator at centrali-has called a station, say B, so that contacts 33, 35, and 45 have been lett out of their norrnaipostions, he can restore said contactsV to their normal positions by sending current along line 2, whereupon it will pass from 2', through 48, 47, 49, 33, 34, and 31, to ground 2S, thus energizing magnet 47 and causin it to return contacts 33, 35, and 45 to their normal positions at B. If contacts 33, 35, and 45 in more than one station have been operated by central in calling IOO IOS

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Y a station, said contacts in the first station on the line from central will be first restored, as above stated, and thus the line 2 in that station will be connected into a through-line by the corresponding contacts 45 46, and a prolonged impulse on line 2 will cause a like operation in the next station, as C, and so on through any station in which contacts 33 35 45 have been operated by central in selecting the signaling instrument in a desired station. An suitable means may be provided at centra for sending current over line 2. I have shown a wire 50 at central leading from line 2 to a contact 51, which is to be connected with a battery and ground, as hereinafter eX- plained. At the last station on a circuit or party-line the lines 1 and 2 are connected together but a metallic circuit through them is normally broken at switch 2C and contact 2f at central. Then two subscribers are to communicate telephonically, the operator at central turns switch 2C to contact 2f to join lines 1 and 2 electrically and restores the annunciator or drop 4 to its normal position, and as contact or spring E normally engages contacts 1aL 2, Fig. 5, a metallic circuit for two telephones is thus established at central, it being of course required that the two suhscribers remove their receivers D from the hooks 12 to allow the latter to engage contacts 19 to include the telephones in the closed metallic circuit. This closed metallic circuit may be traced as follows: from contact 1 at central through line 1, including jack 5 and annunciator 4, to 17 at therst station, B, thence through receiver D and 18, 19, 12, and line 1 to wire 17 at the neXt station, C, thence through receiver D and 18, 19, and 12, back to line 1; (but if there are other stations on the circuit between or beyond. the calling and the called stations the circuit in those stations will be from line 1 through 20, 13, 14, 15, 16, and 12 to line 1.) rIhe circuit leads from line 1 to line 2, thence `through contacts 46 and 45 in the various stations to contact 2f at central, thence through 2C, 2b, 2a, and E to 11 again.

Means to inform the o erator at central that the subscribers have nished talking are arranged as follows: 23a is a contact connected with conductor 23, as by a wire 23h, which contact is adapted to be engaged by switch or contact 14. Now while the tele hones are in the closed metallic circuit descrl ed a subscriber desiring to ring off hangs up his receiver D and causes contact 14 to engage contact 23a, thus breaking connection at contacts 13 14 and establishing a circuit from 1, through 12, 16, 15, 14, 23a, 23h, 23, 22, 21, and 20 back to line 1. He now operates generator 22, which causes current to traverse the closed metallic circuit described, causing annunciator 4 to o crate, thus notif Tin the o erator at centra to disconnect t e laines. T e operator at central moves switch 2c from contact 2f back to 2d, its normal position. If a subscriber on a party-line desires to communicate with a subscriber on another line, the operator at central will connect said lines through their spring-jacks 5 in well-known manner, thus connecting line 1 of one subscriber with line 1 of the other and likewise connecting line 2 of one subscriber with line 2 of the other, and as the closed metallic cir cuit thus formed between the two lines will be obvious it need not be further detailed here.

It is of course desirable to five the operator at central as little work to gdo as possble in answering a call and in callinga subscnber and connecting him with the subscriber he desires. The devices l have provided for these purposes are as follows: The contact or spring E in its normal or home position rests upon contacts 1a 2a to connect them electrically, (see Fig. 4,) and safd contact E is carried by and in electrical connection with an arm 52, that is carried by a shaft 53, so that said contact and arm can be moved around in a circular direction. The shaft 53 is preferably ournaled in the front and back plates 54 55, respectively, of a su.table box or casing, being shown connected therewith by screws 53a 53h, and it may be insulated from said plates, or either said shaft or said plates may be made of insulating material. The shaft 53 carries a handle 56, by which it may be rotated, (see Fig. 2,) and the plate 54 is provided with a circular row of apertures 57, Fig. 3, to receive a plug or pin 58, which is of sufficient length to pass through plate 54, as shown in Fig. 2. The arm 52 carries a contact 59, which is thus electrically connected with contact E; but it is evident that contacts 59 and E could be in one piece, if preferred. The arm 52 also carries a movable contact 60, which is adapted to move in a plane arallel with the movement of said arm. he contact 60 is normally out of engagement with contact 59, but is adapted to engage the latter when pro )erly moved. The plug or pn 58 is adapte to intercept the movement of contact 60 when the latter is earned around by arm 52 and to thus cause contact 60 to engage contact 59 and also arrest the movement of arm 52 at the proper place, Fig. 2, and a stop 60a is provided at the home po nt to be enga ed by contact 6() when arm 52 is returned to orne to move 6() out of engagement with 59. Contact 60 is insulated from arm 52, being shown mounted on insulation 52a, carried thereby, Fig. 5, and is electrically connected. with a contact 61, also carried by and insulated from the arm 52. The

contact 61 is adapted to engage a contact 62, Y

carried by plate 55, when the arm 52 i s swung around; but the contact 62 is so arranged that when arm 52 is at the home point contact 61 will be out of engagement therewith, Fig. 4. Contact 62 is shown in the form of an are of a IOO sienes circle. The contact 62 is connected by a conductor 63 through a battery 64 to ground 65. Contact or spring E is adapted to engage the contact 51, that connects the line 2, which contact 51 is shown carried by plate 55. The line 3 at central connects with a series of contacts 66 66, that are connected toF gether, as by Wires 67, and carried by plate 55,being so arranged as to be engaged successively by contact E When arm 52 is carried around. The arrangement is such that oontact E Will make and break circuit W.th the contacts 66 66, and said contacts correspond wth the different statg'ons on l.ne 3, and these contacts furthermore corres ond with the apertures 57 in plate 55. r.l e cfrcuft through lne 3 and contacts 66 66a is established from ground 65, through battery 64, Wire 63, and contact 62, thence to contacts 61 and 60, thence to contact 59, (when lug 58 has caused 60 to engage 59,) thence tll'irough arm 52, contact E, contacts 66 and 66a to lne 3. To select a desred s'gnahng instrument, the operator at central/places plug 58 in the aperture 57 correspondln to the dcsired instrument and turns han( e 56 to the `rfght in the drawings until contact 60 engages plug 58, wh'ch moves said contact into engagement with contact 59, thus closing circu t to ground 65. Handle 56 is next moved toward home, and as contact E passes over contacts 66 66El the requred number of :ne pulses will be sent over l;ne 3; but contact E remains on 66 untl the call is sent. After a call has been sent from central to the selected signal ng instrument the contact E is rcturned to the home point at la 2a, and in passing over contact 51. a prolonged impulse is sent over line 2, actn successively on Amagnets el? to restore that ne and the parte o erated thereby to the r normal conrLtions. 'Vhen'contact 6() reaches the home pc'nt, it engages stops 60a and is moved out of engagement WV th contact 59, thus preventing any normal crcut from befng formed to ground at 65. lt wll be seen that when contact E is away from contact l.a no call can be received at central over Lne 1, as contacts 1L 2a are then d sconnected.

From the foregoing description it will be apparent that by means of the circuit chang ing or closing devices set forth the operator at central by merely movin handle 56 to and fro can break the norma calling-circuit over line 1, can establish a calling-circuit from central to the station desired, and can then restore the callingcircuits in the various stations, all without iving a call in an Y station on the arty-line gut the one desire 0f course the evices shown can be modified or other circuit-controlling means substituted, if desired.

The complete operation of calling and telephoning with all the devices before described may be summarized as follows: Suppose,

irst, that a subscriber at station C desires to Vtelephone to station B, (contact E at central lbeing normally on contacts 1a 22) he first closes his calling-circuit at Z4 and operates his generator 22, Whereuponcurrent Will flow from ground 25 over line 1, through annunciator 4, to ground 28, as before traced. He then removes his receiver D from its hook V12 (whose spring causes it to engage contact 1Q) and the operator at central places plug I in jack 5, turns switch 2C to contact 2f (thus completing the closed metallic circuit through the telephones at C and central, as before traced) and inquires what is Wanted. When the subscriber tells him the number of the station wanted-say B-the operator at central then places plug 58 in the aperture 5T in plate 54, corresponding to the station desired, and turns handle 56 to the right (thus breakin' Vthe subscribcrs calling-circuit at la) unti contact 60 engages plug 58, which arrests the movement of said handle and also causes contact 66 to move into engagement With contact 59, and as contact E thus cornes to rest on contact 66 the battery 64 is put in circuit with the line 3. (As station B is the first station on the line from central, contact E will oicourse stop on contact 66.) Current will now flow from ground and battery 64 through 63, contact 62, thence through 61, 66, 5?, 52, and contact E to contact 66, thence over line 3, through magnet 36 at station B to ground 28. Magnet 36 (at B) new becomes energized and attracts armature 37, which immediately closes the temporary roundcircuit at 30 39 29, likewise closing t e callingscircuit through 27 at 26 30 and also breaking circuit at 32 33 and at 45 46 and establishing circuit at 35 43 and at 33 49. Contacts E and 66 are noW left in engagement to hold the various circuits in the conditions specified, and the operator at central next closes his circuit for enerator 8 at 9 and sends current from rouler? 10 to line 1 and wire 2U and thence t ough calling instrument 2 and through 27 to ground 28 at B, as before set Jforth. The operator at central next returns the handle 56 to home, during which movement contact E leaves Contact 66, thus cutting cH the current from magnet 36, whereupon armature 37 at B is released, which under the influence of its spring moves back and breaks the circuits at 29, 39, and 30, and hwhen contact E engages Contact 51 current flows from round 65 and battery 64, as before describe to line 2, thence through wire 455, (at 33,) through magnet 47, contact 49, 33, 34, and 31, to ground 28. Magnet 47 (at B) now attracts armature 45, thus closing the line 2 at 45 46, breaking circuit at 43 35 and at 49 33 and restoring circuit at 32 33. The yarious circuits at B will nonr all be normal, and when contact E reaches contacts l 2, coming to rest thereon, contact. 66 strikes 60 and is disengaged from contact 59. The

operator at central next moves switch 2c to contact 2f. The called subscriber (at B) next removes his receiver from the hook 12, which latter then engages contact 19, and. thus conipleti-is the closed metallic circuit through the two communicating tele hones. When the subscribers ring ofl", as be ore explained, the operator at central turns the corresponding switch. 2 back to its normal point on contact 2d thus breaking the closed metallic telephoning-circuit and restablishing the subscribers calling-circuit to ground at 26. If the subscriber at station B had desired to call station C, (instead of C callingB,) he would have called central over line 1 to ground 26, as before explained; but then when the o erator at central started to call station C e would have carried contact E beyond contact 66 and around to the contact corresponding to station C, as 66a, whereupon plug 58 would then cause contact 66 to engage 59. Current flows to ground 28 at station B wher E engages 66, changing the various circuits, as before explained, and when contact E leaves contact 66a armature 37 at B moves back, thus breaking the ground-circuit to 28, but leaving the circuit between stations B and C through. line 3 closed at 37 41 and 43 35 over line 3 and broken at 45 46 over line 2. When contact E engages contact 66, current will flow again along line 3, through 38 37 41 42 43 35 at B, through magnet 36 to ground 28 at C, and change the circuits there, as before described with reference to the operation at station B. Current now being kept on line 3 holds the circuit through 27 to ground 28 closed at C, so a call can be sent from central to C, as before explained, over line 1. Then contact E is next moved to contact 51, prolonged current will flow over line 2 through 48 to ground 28 at B and cause magnet 47 to close the circuit at 45 46, whereupon the current will Howto ground 28 at C, and magnet 47 at C will cause contacts 45 46 to completely restore the line 2, the other changes in the circuits at B and C influenced over line 2 likewise taking place. If there were more than two stations on a circuit, corresponding actions would take place in the various stations between central and the called station, being regulated by the number of impulses sent from central over line 3 by the number of contacts 66 and 66Ii which contact E passes over. It will be apparent that any desired number of stations can be located on a part T-line and that only the station desired wilf be called, as only one calling-circuit from central through 27 to ground 28 can be established at one time and that when a subscriber calls central no call is given in any subscribers station. If a subscriber on a party-line or circuit desires to telephone to a subscriber on another similar party-line or on another ordinary metallic telephone circuit leading to central, it is merely necessary for the operator at central to connect the lines or circuits through their jacks 5 iii well-known manner and call the station.

It will be understood that a subscriber attempting to call over the lines while the line is in use will be unable to obtain a circuit for his generator and bell, and. as his bclldocs not operate he will know that the line is in use.

I do not limit my invention to the precise details of construction shown and described, as the r may be varied without departing from tie spirit thereof.

Having now described my invention, what I claim is* 1. A telephone system comprising a central office and a party-line leading therefrom having a plurality of conductors, telephone and signaling instruments for connection with one conductor, and electrically-operating devices adapted to operate one at a time and successively for selecting and placing in circuit the signaling instrument desired and for restoring the circuits to their normal conditions, means at central for sending the appropriate impulses over the conductors to select and o erate the signaling instrument desired andp for restoring the circuits, means at central for joining two of said conductors in a closed metallic circuit through the telephone instruments, and means corresponding with each telephone for signaling to central over such closed metallic circuit to notify central to disconnect the circuits.

2. A si naling system comprising a central office am? conductors leading therefrom to a plurality of stations, connected in one of which conductors in each station are selecting devices to enable an operator at central tosclect any desired station, signaling devices at each station connected with another of said conductors, and restoring devices at each station connected to another conductor to restore the selecting devices to their normal conditions.

3. A telephone system comprising a central office, a party-line leading therefrom and having a conductor, a plurality of telephone and signaling instruments for connection with one conductor, and means to enable a subscriber to call central, a conductor having electrically-operatin devices to be operated bv current sent om the central ofice to select and place in circuit the desired signaling instrument, and a conductor having electrically-o erating devices to restore the selecting an si naling instrument circuits to their norma conditions by current thrown on the circuit at the central office.

4. A telephone system coni rising a central otce and a arty-line leasing therefrom having main con uctors to one of which are to be connected telephone instruments and signaling instruments on a normally open line,

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and cellroducing instruments also connected wit i said conductor to si nal to centrol, another of said conductors aving electrically-opereting devices to select anu close the circuit of the desired signaling instru-V ment b i current sent `'from central, and iinother o said conductors having electricallyopersting devices for each of said signaling instruments adapted to restore the se ecting devices and the signaling-instrument circuits to their normal conditions by current sent from central.

5. A signaling system comprising a centrel oiiice, and e. party-line leading therefrom having main conductors to one of which ere connected signaling instruments end means for each signaling instrument for producing a cell at central, another of said conductors being divided into sections, erich section correspondin to one of the signaling instruments an having electrically-operating devices to select the desired signaling instrument end to connect two of said sections together to form n through-line all hy current sent over the line from central, and another conductor having electrically-operating devices connected with it corresponding to each signaling instrument to restore the correspending selecting instruments to their normal conditions by current sent over the circuit from central.

6. A telephone system comprising e central office and a party-line leading therefrom heving a plurality ol" conductors, telephone and signsilinfr instruments for connection with one conductor, and means for each telephone to send a cell to contrai, and means at centrsl to operate said signaling instruments, said signaling instrumente heing located on a norinally open line, electricallyoperating devices connected with another of said conductors for selecting and closing the line of the desired signaling instrument and for holding it closed by current sent from central while s Y signal is produced, and ineens connected with another of said conductors for restoring the selectinf devices and the-line of the selected signe ing instrument to their normal conditions. Y

Tf'. A telephone s stem comprising a central oiice and a partyine leading therefrom having a pluralityo conductors, telephone and signalin instruments Jfor connection with one con uctor, end ineens for each telephone instrument to send a call to central, and means at central to operate said signaling instruments, said signaling instruments being located on e normally open line, electricallyoperatin r devices connected with another of said conuctors for selecting and closing the line of the desired signaling instrument and for holding it closed by current sont from centrel while a signal is produced, means connected with another of said conductors for restoring seid selecting devices and the line of the selected signaling instrument to their noi-incl conditions, and means at the central silice for joining two of said conductors in e closed metallic circ-nit throngh the telephone instruments.

S. A telephone system comprising s central silice and a party-line leading therefrom having a plurality of conductors, telephone end signelin instruments for connection with one conuctor and means for each signaling instrument to send a call to central, an means et central to operate said signaling instruments, said signaling instruments being located on a normally open line, electricallyoperatin devices connected with another of seid con nctors for selecting end closing the line of the desired signaling instrument and for holding it closed byciirrent sent from central While a sivnal is produced, means connected with snotlier of said conductors for restorin seid selecting devices and the line of the sciected signaling instrument to their normal conditions, Ineens at the central oilice for joining two of seid conductors in a closed nietellic circuit through the telephone instruments, and ineens correspon ding to each teleplioneior sending a signal to central over a closed metallic circuit to indicate that the closed metallic circuit should he broken.

9. A telephone system comprising a conductor, telephone instruments normally out of circuit therewith and ineens for including them in said circuit, a signaling instrument for each tele hone normally out of circuit, another conf uctor having electrically-operating devices arranged to select the signaling instrument desired end to connect it in circuit with the First-mentioned conductor, and another conductor having electrically-operating devices to restore the signaling-instrument line and the first-mentioned electrically-operating devices to their normal conditions. y

itl. A telephone system comprising n conductor, telephone instruments normally out o'r' circuit therewith and ineens for including them in the circuit, a signaling instrument for eech tele hone normally out of circuit, another conc uctor having electrically-o erating devices arranged to select the signa ing instrument desired and to connect it in circuit with the first-mentioned conductor, another conductor and electricallyoperating devices to he operatori thereby to restore the signalinginstrument circuit and the iirstmentioned electrically-operating devices to their normal conditions, and means Jfor joining the first end lest mentioned conductors to rether in e closed. metallic circuit for the telephones,

1l. A telephone system comprising e. conductor having telephone instruments normally disconnected therefrom, means to connect'tlieni therewith, s signaling instrument for eecn telephone, ineens for operating the IDO same, another conductor connected with the first-mentioned conductor at one part and normally disconnected therefrom at another part, means for joining said conductors in a closed metallic circuit, means corresponding to each telephone for breaking the first-mentioned conductor and connecting it through the devices that operate thc correspondingr signaling instrument, and a circuit having electrically-operating devices for selecting the signaling instrument desired.

12. A telephone system comprising a main line including hooks or contacts 12, and switches or contacts '14, telephone instruments located on. branch lines connected with said main line adapted to be electrically connected therewith by said hooks or contacts 12, signaling instruments for each telephone connected withsaid main line, currentproducing devices connected with said signaling instruments and a contact connected with said current-producing devices to be engaged by the contact 14, another line adapted to be connected in a closed metallic circuit with the lirst-n'icntioned line, an indicating instrument to be operated by current on said` closed metallic circuit, and another line having electrically-operating devices to select the signaling instrument desired and connect it with the lirst-mentioned line in condition to be operated by current sent thereover.

13. An electrical circuit comprising a main line including contacts 13, 14, 16, and 12, branch lines extending from said conductor including telephone instruments and each having a contact to be engaged by the correspondmg contact 12, normally open branch lines corresponding to each tele hone instrument extending from said main inc and cach having a signaling instrument, current-producing devices connected with each of said brano i lines and having a contact to be engaged by the contact 14, another line to be Joined with said main line to form a closed metallic circuit, and a line having electricallyoperating devices to select and close the branch hne of the signaling instrument desired.

14. An electrical circuit comprising a main line including contacts 13, 14, 16, and 12, branch lines extending from said main line including telephone instruments and each having a contact to be engaged by the correspending contact 12, normally open branch lmes for each telephone instrument extending from said mam line and each having a signaling instrument, currentreducing devices connected with each o said branch lines and having a contact to be engaged by the contact 14, another line to be joined with said main line to form a closed metallic circuit, a line having electcaiiy-operating devices to select and close the branch line ofthe signaling instrument desired, and electricallyoperating devices connected with the second mentioned line to restore said selecting de vices and the branch lines to their normal conditions.

15. A circuit divided into normally grounded sections, electrically-operating devices for breaking said grounds and joining two sections together, another normally closed circuit having contacts to break it into sections, and electrically-operating devices connected in normally open circuits extending from the sections oi the second-mentioned circuit to restore the sections of said circuit to their normal condition, the first-mentioned electrically-operating devices being arranged to close the circuits for the electrically-operating devices of the second-mentioned circuit.

16. An electrical circuit divided into normally grounded sections, electrically-operating devices connected with each section to break the ground of said section and to join two sections together, contacts to form a temporary ground for said sections, another normally closed circuit having contacts to break it into sections, branch lines extending from the sections of said circuit and each having a contact to be engaged by a contact of sald electrically-operating devices to establish a ground for the section of the second-mentioned circuit, and electrically-o erating devices connected with said brancli line to restore the first-mentioned electrically-operating devices and to join thesections of the second-mentioned circuit.

17. A telephone system comprising a conductor, telephone instruments, and normally open branch lines connected with said conductor for each telephone, a signaling instrument connected with each branch line, contacts in cach branch line to make and break the same, another circuit divided into normally grounded sections, electrically-operating devices to break the grounds of said sections and join two sections together and to operate the contacts of the signaling-instrument branch lines to make and break said lines, and means for restoring said circuits to their normal conditions.

18. A tele hone system comprising a conductor, telep one instruments, and normally open branch lines connected with said conductor for each telephone, a signaling instrument connected with each branch line, contacts in each branch line to make and break the same, another circuit divided into normally grounded sections, electrically-operating devices to break the grounds of said sections and join two sections together and to operate the contacts of the signaling-instrument branch lines to make and break said lines, and another circuit having electricallyoperating devices to restore sald circuits to their normal conditions.

19. 4A telephone system comprising` a central oilice, a conductor leading therefrom,

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telephone and signalingv instruments there- I with said conductor and the other being confor, means for operating the latter, and an indicating instrument at central on said conductor, contacts and conductors connecting said conductor with ground and adapted to break the circuit of said conductor, another conductor connected with the first-mentioned conductor and leading to central, contacts to connect said conductors at central in a closed metallic circuit, another conductor having electrically-o erating devices to select the desired signa ing instrument, the second-mentioned conductor having electricallyoperating devices to restore said selecting devices, and means at central for operating the devices connected with the second and third mentioned conductors.

20. A telephone system comprising a central oflice and a arty-lineleadmg therefrom having two con uctors together at one part and normally disconnected at central, telephone and signaling instruments for one of said conductors, and an indicating instrument at central on said conductor, means for operating said signaling instruments and the indicating instrument, a pair of contacts one of which 'is connected with said conductor and the otherbeing connected with ground through a switch, a contact to connect said two contacts, a contact connected with the second-mentioned conductor to be engaged by said switch to join said conductors in a closed metallic circuit through the telephone instruments, another conductor having electrically-operating devices to select the desircd signaling instru ment, and means at central for operating said selecting devices.

21. A tele hone system comprising a central oiiice and a party-line leading` therefrom and having two conductors connected togather at one part and normally disconnected at central, tele hone and signaling instruments for one ol) said conductors, and an indicating instrument at central on said conductor,n1eans for operating said signaling instruments and the indicating instrument, a pair of contacts one of which 1s connected nected with ground through a switch, a contact to connect said two contacts, a contact connected with the second-mentioned conductor to be engaged by said switch to join said conductors in a closed metallic circuit through the telephone instruments, another circuit having electrically-o erating devices to select the desired signa ing instrument, electrically-operating devices connected with the second-mentioned conductor for restoring; said selecting devices, and means at centrai for operating said selecting` and restoring devices.

22. A central station, a continuous metallic line extending therefrom, a second nictallic line extending therefrom and broken at a series of stations, a third line arranged to complete the circuit from each station to the central, and switch mechanism at each station arranged to successively and automatically break the third circuit connection from cach 'station to central and build up the broken line through each station.

23. In combination, a central station, three lines leading therefrom to a series of substations, and electromagnetic selective apparatus at each of said substations adapted to be connected in series with one of said lines, and adapted to he connected in multiple with either of the other two lines.

24. In combination, a central station, three lines leading therefrom to a serios of substations, electromagnetic selective apparatus at each of said substations adapted to connect said selective apparatus in series with one of said lines and to make or break a multiple connection With each of the other two lines when actuated by suitable electric impulses, and means for causing suitable impu ses to flow through said electromagnetic selective apparatus.

CHARLES B. SMITH.

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