US1394723A - Toll-telephone switching apparatus - Google Patents

Description

H. M. FRIENDLY AND A. E. BURNS. TOLL TELEPHONE SWITCHING APPARATUS. APPLICATION FILED JUNE 7, i915- RENEWED MAR- 1,!921- Patented Oct. 25, 11921 4 SHEETS-SHEET I.

H. M. FRIENDLY AND A. E. BURNS.

TOLL TELEPHONE SWITCHING APPARATUS. APPLICAIION FILED JUNE 1, I915- RENEWED MAR. 1, I921.

Patented 001; 25, 192-1:

4 SHEETS-SHEET 2.

H. M. FRIENDLY AND A. E. BURNS.

TOLL TELEPHONE SWITCHING APPARATUS. APPLICATION FILED JUNE 7,1915. RENEWED MAR. 1,192]. 1,34,723. Patented Oct. 25, 1921.

4 SHEETS-SHEET 3.

H. M. FRIENDLY AND A. E. BURNS. TOLL TELEPHONE swncums APPARATUS.

jhnf/vro/Ps UNEFE -FA'TS PATENT @FFECEQ.

HERBERT M. FRIENDLY AND ARCHIBALD E. BURNS, OF PORTLAND, OREGON; SAID BURNS ASSIGNOR TO SAID FRIENDLY.

TOLL-TELEPHONE SWITCHING APPARATUS.

Specification of Letters Patent.

Patented oct. 25, 192i.

Application filed June 7, 1915, Serial No. 32,767. Renewed March 1, 1921. Serial No. 448,869.

To alZ whom it may concern Be it known that we, HERBERT M. FRIENDLY and ARCHIBALD E. BUnNs, residents of Portland, Multnomah county, Oregon, have invented certain new and useful Improvements in Toll-Telephone Switching Apparatus, of which the following is a specification.

Our invention in its fullest embodiment consists in means for remotely effecting connection and disconnection of toll lines, and of providing visual and auditory signals, and other-means to facilitate the operation of same alone and in conjunction with independent lines adapted to be connected with said toll lines. An object is to reduce the manual effort necessary in methods heretofore employed in establishing such service.

Conditions met impractical telephone operation vary in electrical structural and operative details due to manifold reasons. The peculiarities of electrical circuits and devices incident to individual switchboards, as well as the varied conditions of trafiic and the handling of same, demand subordinate and detailed modifications of our invention for practical .and commercial application to specific cases. So it is impossible to devise apparatus for such varied adaptations and means of employing it, the object of which is to perform certain functions and then apply universally to all toll lines and incident equipments the devices with details unchanged. Therefore, the specifications and accompanying drawings hereof illustrate and refer only to one of many possible and practicable applications of our invention. It is manifest that features of our invention can thusbe employed as an amplification, or without its adoption as an entirety, andthat the details of construction and operation can be varied and applied within wide limits and without departing from its scope by those skilled in the art to which it belongs.

In the accompanying drawings:

Figure 1 is a diagrammatic conventional representation of two toll lines adapted to be interconnected and disconnected.

Fig. 2 is a diagrammatic conventional representation of essential parts of a common form of connecting-cord circuit adapted to use in connection with Figs. 3, 4 and 5, and

point of interconnection as Fig. 1.

Fig. 4 is a diagrammatic conventional representation of the essential parts of equipments and electrical circuits as used at the station A4, Fig. 1.

Fig. 5 is a diagrammatic conventional representation of the essential parts of equipments and electrical circuits as used at the station A5, Fig. 1.

Fig. 6 is a front elevation of the frame containing a portion of the apparatus shown as associated with the switchboard equipment proper, Fig. 4.

Fig. 7 is a side elevation of a dustproof and cross-talk proof cover adapted to go over front of Fig. 6 to inclose relays.

Fig. 8 is a right side elevation of frame shown in Fig. 6. i

Fig. 9 is a plan elevation of terminal rack and rocking switch shown at to of Fig. 6.

Fig. 10 shows a detail of mem er 43, used for carrying relay R5. Members 41 and 42 are similar.

Fig. 11 shows details looking to right of section A B, Fig. 10.

Referring to the figures in detail:

Fig. 1 shows an application of our invention as applied to two toll lines adapted to be used as one continuous line. The dotted lines at A3 denote a possible connection between the two lines D and E; s1, s2 and s3 denote bridging signals of common types connected at stations on line E; and s4, s5 and s6 denote similar signals at stations on line D. 1 and 2 refer to terminals of equipment set corresponding to the same designa tions in Fig. 4; 3 and 4, 5 and 6 correspond to terminals of an equipment set corres ond ing to the same designations in Fig. 3; and

at the station A3,

.8 refer to terminals of an equipment set corresponding to the same designations in.Fig. 5. Thus, A4 denotes Fig. 4; A3 denotes Fig. 3; A5 denotes Fig. 5.

A function of the arrangement indicated by Fig. 1, which we will use to exemplify and elucidate our invention, is:

To enable an operator at station A4, for instance, to signal and establish a telephonic connection along the line D; also to similarly enable an operator at station A5, for instance, to signal and converse along the line E; further to incidentally enable the operators at stations A4 and A5 to cause the lines D and E to be interconnected and disconnected at will, at the station A3; further, to permit operators at stations shown to interconnect local or independent lines with the lines specifically indicated by means of a common form of cord sets. There are other incidental functions which will be referred to later in these specifications and subjoined claims.

In the following, we will describe the physical operations and incident electrical functions attendin the establishment and disestablishment o a telephonic connection between station A4 on line E and station 86 on line D, under control of the operator at station A4, Fig. 1.

Referring to Fig. 4, the terminals of springjacks J 1, J2 and J3 are in multiple relation; also, the terminals of springjacks J4, J5 and J6 are in multiple relation; also, the terminals of the lamps jl, 7'2, 7'3, 7'4, 3'5, y'6 associated with and drawn immediately above the said springjacks respectively are in multiple relation, one side of which circuit is connected to battery B1.

For convenience of description, we will term the jack J3 the regular answering jack, and associated jacks J1 and J2 regular multiple jasks. In a like manner J6 will be termed the regular through switching jack, and associated jacks J4 and J 5 will be termed through switching multiple jacks. The functions and uses of jacks J1, J2 and J3, and J4, J5 and J6 are the same respectively. So, for further convenien'ce of description, we will refer to jacks J3 andJ 6 respectively, omitting mention of their said multipled ac s.

In Fig. 4, it will be observed that terminals e1, e2; e4, e5; e7, e8, respectively, of jacks J 1, J2 and J3, are directly connected with terminals 1 and 2 normally, and thus stations as s1, s2, s3 and A3, Fig. 1, are normally conductively associated with J1, J2 and J3 by way of conductors 2'4 and 2'5, while the terminals e10, e11, e13, 614, e16, 617, respectively, of jacks i4, 95 and 9'6, are only connected to terminals 1 and 2, over conductors 2'2 and 21 respectively, .after a plug as p1 has been inserted into one of the latter jacks. Further, as will be shown later, the interconnection of lines E and D at station A3, Fig. 1, is accomplished simultaneously with the insertion of said plug p1 into jack J6, Fig. 4, thus obtaining access to the line D from station A4 on line E. Referring again to Fig. 4, relays R1 and R2 are in multiple relation with relay 2R, the circuit including the relay R2 being through the contacts 10-20, 30-4c and 5060 of pushkeys n1, a2 and 123 respectively. Thus upon insertingplug, as p1, into any one of the jacks J4, J5 or J6, relays 2R, R1 and R2 will actuate directly. The function of relay 2R has been described. Bearing in mind the actuated conditions of both relays R2 and 2R, the function of relay R1 is: First, to "round conductor 23 through contacts a2a3. This will energize relay 1R, thus disassociating signal device Dl over regular answering jack J3, at contacts 31-41- and 5r--6r and also close circuit through lamp j3 and its multipled lamps jl, j2, '4, 7'5 and 7'6 byway of 1r--2 rto ground (1, the latter closed contacts being in multiple with similarly related contacts, 7r-8r, of relay 2R. Second, relay R1 opens contacts a4-a5, making contacts a-5a6, thus changing the ground applied to terminal 66 of polarized relay R5 to battery F, and removing the ground normally on terminal 61 by the contacts a1a2 opening. The latter contacts opening render the relay R5 ineffectual by virtue of destroying its secondary or local circuit continuity from its said terminal 61.

Relay R5 is differentially connected between its terminals 67 and 58. That is, any currents applied serially between these terminals will not exert a tractive effort on the armature 125. However, to currents applied through the said relay in derivation from terminal 66, armature of said relay will be directionally operative. Currents from battery F tend to operate its armature 65 in its indicated plus direction and further open contacts b1b2 and. 63-64 respectively.

For convenience, we will refer to certain polarized relays as operating in a plus or minus direction, arrows indicating movement of the end of armature.

Repeating coil or inductorium C1 ismade up of two inductively related windings, which for convenience will be termed primary and secondary windings. The primary winding is made up of two sections (ll-112x105 and d5-d6 connected cumulatively in series. The secondary winding is made up .of sections d3d4 and d7d8, the latter section windings correspondin with the primary windings as regards direction.

Battery current from battery F finds its Way derivedly to terminals 1 and 2 from contacts w12a11; thence to contacts a6-a5; thence to relay terminals b6-b9; thence cumulatively through relay R5 to terminals b7 and b8; thence to terminals 454 and (Z8 of secondary windings of repeating. coil C1; thence from terminals 033 and d7 respectively to line terminals 1 and 2, Fig. 4. From the latter terminals the derived currents are conducted in parallel over the limbs of the line E, Fig. 1, to terminals 3 and 4, Fig. 3, which is shown as station A3, Fig. 1; thence through contacts g44- 45 and 946-947 respectively of relay 3R; thence toterminals g5 and g7 of polarized relay R6; thence differentially to terminal 10 of same relay. From said terminal 10 there are two aths to terminal 911 of relay R8 in derived relation. One path is serially by way of Contacts 91-92 and 93-94, relay R6; thence to terminal 916, relay R7; thence serially through relay R7 to terminal 18; thence throu h contacts 926-927 and g28-g29, relay 8; thence through relay R10 by way of terminals 973 and 974; thence to common or junction point 11. The other path from 10 to 11' is through the associated relays R7, R7 and resistance 9 21, the detailed operation of of which will be explained later. From terminal gll the current path is difi'erentially through rela R8 to terminals 922 and 924 thereof; t ence through contacts g57-g58 and g59g60 respectively of relay 5R; thence to terminals |5 and 6; thence in parallel over line D, Fig'. l, to terminals 7 and"8,' Fig. 5. Fig. 5 is shown as station A5, Fig. 1. The description in detail of Fig. 5 will betaken up later. Sufliceit to state here that with apparatus in Figs 3 and 4 in the position described, current from grounded battery F, Fig. 4, flows to termi nals 7 and 8 over parallel at G3, Fig. 5, as follows From terminals 7 and .8, Fig. 5, the circuit may be traced to terminals 67 and c3; thence through the sections of the secondary windin of said repeating coil C2; thence to terminals f39 and f48 respectively of relay R17 by way of terminals 68 and c4 paths to ground respectively; thence cumulatively through windings R17 to terminal f38; thence through contacts f7-fd of relay R12 to ground G3. Indicated windings of repeating coil C2 are similarly disposed to the indicated windings of coil G1, Fig. 4.

Relay R6, Fig. '3, is a polarized relay bridged between terminals 3 and 4 by way of contacts g44-g45 and 946-947 respec tively of relay 3R. Relay R8 is asimilar relay bridged between terminals 5 and 6 by way of contacts g57'g 58 and g59--g60 respectively of relay 5R. The section wmd- .ings of relays R0 and R8 are so disposed with regard to terminals 10 and 911 respectively that any currents passin to or from said terminals are equally an diiferentially divided through the windings of the respective relays and will thus produce no efiect as regards any tractive efi'ort on armatures g9 and 30 respectively.

All currents passing through the polarized relay R7 by way of terminals 16 and 18 will exert a tractive effort upon the armature 20, which controls contacts 12-913 and g14-g15, normally open. Re-

lay R7 being sensitive to directional cur-' rents and the current from battery F, Fig. 4, being negative, since the battery F has its positive pole grounded, the current from battery F is therefore assumed to PflSS ID'tO relay 7 at terminal 916 and out of it at terminal 918. The relay R7 is designed to move its armature 20 so contacts 912 and 914 are placed into electrical conductivity with contacts 913 and 915 respectively, upon the passage of said negative currents from battery F. VVe therefore refer to said movement of armature 20 as having moved in a minus direction as designated by arrows. Incidentally, currents emanating from a battery or other source substituted for battery F, having the negative pole grounded, will project currents of opposite direction through relay R7 and cause its armature 20 to move in a direction opposite to that required to close its contacts 912 and 914 with 913 and 15 respectively or in a plus direction. Re ay R7 is thus designed to close contactsv g12g'13 and g14gl5 upon passage of negative currents or currents in direction from 916 to 18 only. The object of this directional characteristic in relay R7 will be shown later.

Relay R9 is controlled supplementarily by said contacts 912-913 and 914-915, and therefore by the direction of parallel or derived currents applied to terminals 3 and 4 over line E. Relay R9 in turn will, through contacts 933-934 and 935-936, complete the telephonic circuit between terminals 3 and 4, and 5 and 6. The condensers tl-lt and t2-2t, while transparent to ordinary telephonic and alternating currents, are opaque to the direct and constant currents for manipulation, such as are applied to normally actuate relay R7 as described. Thus all manipulative currents to, rom, or between the lines E and D are constrained to normal paths regardless of the position of relay R9.

Relays R11 and R9 are in secondary or local relation to relay R10, and furthermore the relay R9 is dependent upon the primary operation of relay R10. Upon relay R10 acting in response to currents coming from battery F, as previously described, relay R11 will be battery B2 to ground through contacts g37g38g39 of relay R10. The action of relay R11 causes multipled lamps 9'21 and 3'22 to glow through contacts 941-940; also the action of relay R10 causes ground G2 to be applied to contact 912, relay R7, through contacts 938-937. Thus it will be observed the following cycle of operations must ensue before relay R9 can obtain actuating current and close the telephonic connection between terminals 3 and 4, and 5 and 6 by its contacts g36-g35 and g34g33 respectively; the actuation of relay R7 in the indicated minus direction, thence successively relays R10 and R9. The objectof this succession of relay functions is to retard, by reason of inertia and inherent relay time element, any current impulse applied to the said limb of the derived circuits between 10 girl, to a de ree sufficient to prevent relay R9 from obtaining actuating actuated by current from local connection between 3-4 and 56 will be accomplished as long as current is sustained from battery F to ground G3. To further forestall occurrence of false interconnection or telephonic interference between the lines D and E, Fig. 1, by reason of signal'impulses or alternations, for instance, applied between the limbs of the telephonic circuit, the derived limb between 910 and gll including the relay R10 is carried through contacts g1g2 and 93-94, relay R6, and contacts g26-g27 and g28-g29 of relay R8. The polarized relays R6 and R8, being bridged between terminals 3 and 4, and 5 and 6 respectively, as previously described, currents of proper character applied between the limbs of the telephonic lines will actuate its corresponding relay R6 and R8, as the case may be, or possibly both of said relays,

if relay R9- is actuated. Thus, when a' bridging current is applied between terminals 3 and 1 0r 5 and 6, as a single phase ringing "current, for instance, the derived limb including relay R10 will be opened, thereby making an interconnection of the lines D and E, Fig. 1, impossible.

Lamps y'21 and 7'22, Fig. 3, are located so as to indicate to separate operators at station A3 when lines-D and E,'Fig. 1, are interconnected. The said lamps are under the control of relay R11, and this relay having the characteristic of slow or retarded release, insures the steady glowing of said lamps during lapses in the current of short duration, to which its controlling relay R10 is responsive. The occurrence of this lapse will be explained later, in connection with description of signaling functions.

Apurpose of resistance involved in the circuits between terminals 9104 and 9105, Fig. 3, is to prevent a complete opening of the manipulative circuit from battery F to "round B3 in the event of the derived limb, lncluding the relay R10, becoming opened under conditions previously adverted to. The object of retaining this circuit continuity between 910 and 911, Fig. 3, under all operative conditions, will be shown later in connection with the description of signaling functions.

A second pur )ose of the circuits and equipments R7, 7" and 21 between the terminals 9104C and (7105 is to cause the cutoff relays 4R and GR to disassociate the signaldevices D3 and D4 respectively when direct current is sustained through R7, as for instance, while manipulative currents are applied between the terminals 3 and 4, and 5 and 6 in parallel. Thus when lines D and E are interconnected or when a sig naling' current is applied through the agency of relay R5 or. relay R17, the si nal devices D3 and D4 are disassociated. ther functions may also be accomplished, as actuating a relay adapted to cut ofl jacks during interconnection to preclude access to lines by operators during duration of through connection. Current of a transitory or alternating nature as a single phase alternating current of frequencies met in telephone practice, will not cause the relay R7 to actuate-by reason of its armature being retained through the tractive effort of the pole pieces of relay R7" during the passage of varying currents as mentioned.

Relay R7" is made up of two like winding connected differentially from common terminals 9104 and 9114; the free terminals of the respective windings connect to the noninductive resistance 921 and relay R7, joining at common oint 9105. The armature 9110 of relay 7 has attached to it a nonmagnetic connecting yoke g106 carrying a magnetic armature piece 9107 in attractive relation to opposite pole pieces 109 and 9115 of relay R7. When a current of an alternating nature, for instance, passes in at terminal 910 and out at terminal gll, the upper and lower windings ofrelay R7" obtain currents of unequal strength by virtue of the properties of the branches of equal ohmic resistance including the relay R7 and resistance 921. Though said relay and said resistance have equal ohmic resistance, they present different impedances to currents of inconstant nature. Therefore the armature piece 9107 will be attracted'to its related pole pieces 9109 and 9115 by the electromagnetic efi'ect of the preponderant helix, preventing the armature 9110, to which it is rigidly attached, from actuating contacts g101-g102-g103 to apply ground G2 on contact 9101 to the free sides of relays 4R and GR, actuating them to disassociate signal devices D3 and D4 respectively. To sustained direct currents of either polarity the current dividing between the two ings of relay R7 will be equal, and by reason of being differentially connected will produce a null efiect upon the armature piece 107. Thus the armature of relay R7 will be unrestrained. and free to close its contacts 101g102-g103, causing the relays 4R and closing its contacts f ies-M5 and fad-747 respectively. As a consequence of the closing of the said contacts, current flow is established between battery B3, which is common to one of the common wires forming the multiple connection between the lamps f7, j9,

7'12, jl l, '16 and 19; over. the other common wire 62' of said lamps; through said contacts of relay R17, through relay E16 by way of its terminals f35-f34; to ground G3 by way of contacts f3f4 of relaly R12. .By virtue of this current through relay R16, its con tacts f36f37 will open. This opening of contacts will open the conductor 77: between the multipled terminals e30, 633 and e36 respectively of jacks J 10, J 11 a d J 12, the object of which will be shown later.

For convenience of description, we will term the jack J 9 the regular answering jack, and the associated jacks J7 and J8 regular multiple jacks. In a like manner J 12 will be termed the regular through switching jack, and the associated jacks J 10 and J11 may be termed through switching multiple jacks. The function and uses of jacks J7.

J8 and J9, and J10, J11 and J12 are the same respectively. So for the convenience of description, we will refer to jacks J9 and J 12 respectively, 0 itting mention of their said multipled jacks. It will be noted that there are additional lamps 7'11 and 7'18 associated with jacks J9 and J 12 respectively.

The said lamps are for the purpose of incoming signals. Their control and functions will be described later.

In order to convey a calling signal to the desired station 86 from A4 wlth plug p1 in jack J6, the following physical operations and incidental electrical functions will take place :The operator at A4 will depress the pushkey 113, thus opening the circuit from ground G through conductor 1e of plug 'pl by way of jack terminal 618; contacts 50 -60 of said 123; contacts c3c4 and 01-02 of ushkeys a2 and 71.1 respectively; to battery 1 byway of terminals a11a15 of relay R2, thus deenergizing said relay. Contacts all-a12 applying negative current from battery F to terminal 66 are opened and contacts a12-a13 are thereafter made, applying positive current from battery B1 to said terminal 66. It is because of this lapse in cur rent during the interval of changing polarity that the relay R11, Fig. 3, is given the retarded release characteristic previously mentioned. Contacts a7-a8, and ail-(r10 are opened, disassociating. contacts 011 and cl-t of relay R4 from direct connection to termi-- nals 1 and 2 respectively. The positive current now applied to terminal 66 of relay R5 follows the same course as the negative cur-' rent before in reaching G3, but due to the directional characteristics of relays R5, Fig. 4, R7, Fig. 3, and R17, Fig. 5, the following circuit changes will ensue:

The armature b5 otrelay R5 will move in the indicated minus direction closing its contacts b1--b2 and bit-M. However, the circuit including the said contacts will still be open at contact a1, since R1 is energized. The armature relay R7 will move in the indicated plus direction, thus opening its contacts g12gl3, and g14lg15, and in turn the helix circuit of dependent relay R9, incidentally opening the contacts 933-934, and 935-936, opening the telephonic circuit between terminals 3 and 4, and 5 and 6.

The armature of relay R17, Fig. 5, will move in the indicated minus direction, thus opening its contacts fe l-7 45, and f46f47 and closing its contacts 740- 11, and f42- f43. As a result of these unctions, conductor 62' is opened, thus extinguishin the associated lamps 7'7, j9, 9'12, jl i, '16, an 3'19. However, as will be seen later, this is for only a short interval while a signaling impulse is applied; also, the circuit from battery B3 is closed through relay R14. by way of its terminals f19 and 718 through the said contacts of relay R17 through relay E16 by way of its terminals f35-f34.- to ound G3 by way of contacts f3f4,, relay 12. Incident to the actuation of relay R14, its dependent relayR-15 is actuated due to closing of circuit from battery B3 by way of its helix terminals f32 and f33; contacts [21- f20 of relay R14 to terminal f18 of sald relay; thus placing relays R14 and R15 in multiple relation. Contacts f22-f23 will close the circuit from ground G3 through relay 7 R- to batter B3 by way of conductor 32'. The function 0 relay TB is to disassociate the relay R19 which-is bridged across the terminals e25 and e26 of answering jack J 9; to incidentally close circuit of lamps 7'8, '10, 3'13, 715, 3'17, 920 to ground G3 by way 0 its contact 7c3ls4;; causing said lamps-to glow during the duration of the signaling impulse; to open conductor 10i at contacts I01 52 of said relay. Contacts f24.f25 will short-circuit terminals 6 1' and e8 of repeating coil C2, and also terminals f39 and i418 of relay R17 respectively, however not altering the operative function of said relay by so doing. Ringing or signaling current from source P3, which may be of the usual alter- 11 nating character,.is imfpressed serially upon terminals 61 and e5 0 repeating'coil-C2 by way of contacts f26--f27 and contacts 729-730 respectively of relay R15. The circuit through primary sections of said are 120 peating coil is by way of conductor between its terminals 62 and e1. The ringing current is thus inductively transformed to pure loop current, which is projected from terminals 63' and 67 across the line terminals 125 7 and 8 and out upon the line D across which the signal device at station 86 is connected in bridge, actuatin said signal device. Coincidently, current rom source P3 is appliedto conductors 4i and 5tv through contacts 180 ,multiple relatlon respectively. Therefore,

in each contact movement of said armature, circuit from battery B3 is completed through relay R24 by way of its terminals f103 and f102 through resistance f104; through its contacts f100-f101; through the said contacts of relay R22; through relay R23 by way of terminals f96 and f95; through contacts .7c97c10 of relay 8R to ground G3. Contacts f100--f99 are designed to make before contacts f101f100 break, to avoid breaking the continuity of circuit described between contact spring flOO and battery B3. Bela R24 will lock in its operated position by virtue of obtaining constant ground on its terminal 102 by way of its contacts ;100-f99 an contacts 709-7010 of relay 8R. t will unlock only upon the opening of the latter contacts as by the actuating of said relay upon the insertion of a plug as 721, Fig. 2, lnto jacklJ 12, applying groundG to relay terminal 70 by way of jack terminal 636 of said rela by way of conductor 16 of said plug. Re ay R23 will actuate upon closing of said contacts of relay R22, opening circuit from battery B3 through contacts f97f98 of said relay R23; through resistance Q04 through contacts f100f99 of relay 24; through contacts 709-7010 to ground G3. The relay R23, Fig. 5, will remain actuated as long as each series of signaling impulses is maintained by reason of pushkey 123, Fig. 5, be-

ing depressed successively. Thesaid relay R23 remaining actuated is by virtue of it having a retarded release characteristic, though the contacts of relay R22 remain closed only during a portion of the period of each actuating impulse impressed upon said relay R22, as described. After the vibrations of armature f84 of relay R22 cease, the armature of relay 23 returns to normal, thus allowing contacts f98-,f97 to be made and the described circuit including the lamp '18 reestablished, causing said lamp to glow. Thus it will be observed lamp 7'18 glows at the cessation of each series of impulses impressed upon relay R-22, and then remains glowing until extinguished as by the insertion of plug as 721 into jack J12, as described. From the successive glowings of said lamp 9'18 the operator observing it can determine what code signal is being sent.

The purpose of resistance [104 is to restrict current through lamp j18, when current from batter B3 is drawn from terminal f102, relay 24, through said resistance in place of through relay R23 by way of contacts flOO-f99, as described, after the relay R23 returns to normal, for in this latter position of said relay R23, current from battery B3 through lamp 7'18 reaches ground G3 by way of contacts f97--f98 and resistance 104'; through terminals f102 and i103 of re ay R24.

Upon the release to normal of pushkey 713 the former condition of circuits ensues, the lines E and D being reconnected. The described cycle of circuits and incidental electrical functions will take place upon each depression of key 013, thus signaling current will be impressed back and upon and along line D, while line E is telephonically cut oil from said line D in conformity with the successive depressions of said key 113 to form any ringing code, as the series of signals to which station 36 will respond.

It is to be observed, that while station 86 was specifically signaled in code, the signal device, lamp y'18, was displayed in code over the through switching jack 7'12, and not signal device, lamp jll, over the regular answering jack J 9, thus indicating to the operator at said jack J 12 that not only is a code call being made to signal station .96, but that it is coming from station A4 on line E and not from some station on line D. Sig nals coming from stations along the latter line would be displayed by signal device, lamp 7'11, over the regular answerin jack J9, which is directly associated with said line normally. This function will be described later.

Lamp signal devices, j7', y'9, j12, i1 4, jl6, and 9'19 associated with jacks J7, J8, J9, J 10, J11 and J12 respectively are in multiple relation. They will glow upon obtaining current by way of conductor 6i and contacts 44f45 and f46-f47 of relay R17 thence y way of f34 and f35 through terminals f3-f4 to ground G3. This will ensue when a plug as p1 is inserted in any of the through switching jacks at station A4, thus indicating to operators at station A5 when the lines are interconnected at station A3 under control ofstation A4. Aside from this indication, the glowing of the said lamps, or more particularly-the lamp 3'19, may be used to indicate to the operator at jack J 12, station A5, that the station A4 desires her response.

If through carelessness or coincidence, the operator at A5 should insert a plu ,as p1, into the regular through switching ack J 12 during the course of a series of signals sent from pushkey n3, the open relay contacts f36- 37 of relay R16 will preclude the relays 12 and R13 from operating by way of ground G obtained through conductor 7i; by

'way of its terminals .into throu h switching way of jack terminal e36 and plug conductor 16. -Were not this provision made in contacts of relay R16 the consequent actuating of relays R12, R13, due to the said insertion of plug p1, would cause relay R14 and-its dependent relay R15 to not obtain ground G3 by way of contacts f42-f 13, and f40-f41 respectively, through relay R16 by f35 and f34 to contacts f3-f4 of relay R12. Since signaling current is applied to line D by relay R15, the incapacitating of relay R15 as by the functions consequent to the inserting of plug as 121 into J12 would interrupt any signal impulses under way. Relay R16 is given the characteristic of retarded release, so that this relay will have its contacts open during the entire course of transmitting a signal code, the intervals between signals of the code being assumed to be shorter than the release time characteristic of said relay.

If the code signal for station A5, in lieu of that of station 86, is made at station A l, as described, the operator at station A5 will respond by inserting a plug as pl, Fig. 1,

jack J12, disassociating relay ll-22 as previously described, and also causing relays R12 and R13 to actuate by way of contacts f36 and f3? of relay R16, as previously described, it being borne in mind that relay R16 will return to its normal position in a short interval after the termination of last impulse of the signal code sent from pushkey 713. In the said state of the relays R12 and R13, positive battery B3" will be applied to terminal f38 of relay R17 by way of contacts f13-f14 of relay R13, and contacts f8-f7 of relay R12. It will be observed that this positive battery will be in series with the battery F coming from station A4 by virtue of a plug as p1 being inserted in springjack J6, pushkey 123 being normal. Jack J6 and jack J12 are now in telephonic connection through switching cord sets as p1 at the respective stations. It will be further observed that should operator at station A41 withdraw plug as p1 from jack J6, the lines D and E would remain interconnected by virtue of the current emanating from battery at station A5, as described, finding ground G1 by way of terminals (to-a4, relay R1 at station A4.

Should the operator at A5 desire to signal the station A4, the operatipn would be to depress the switching cord set ringing key 3k corresponding to the signal. code of said station A4. The functions of relay 8R incident to the insertion of the plug into jack J12 have been described. The application of current from. the source P2, over conductors 3p and 4p, Fig. 2, will cause the relay R18 bridged between jack conductors e34. and 035, connected respectively by way of conductors 4d and 5?; to series terminals 56 and f50 of said polarized relay H18 in bridged relation. The latter relay being sensitive to directional currents of either or both polarities, the armature f56 of said relay will vibrate responsively incidentally opening its contacts f55--f56, /53f52, successive thus opening the circuit between batte B3 through terminals fl? and {16 of relay 13 to ground G of plug 721 by way of contacts ,37-f36, conductor 72', jack condu'ctor e36 and plug conductor 16. The deenergizing of said relay R18 will cause the contacts fl3-f14 to be opened, and the con-,

tacts f14-fl5 to be made, thus applying negative battery H to the described circuits in lieu of positive battery B3 formerly applied. Incidental to this, relay R7 will be actuated in its indicated plus direction, thus opening its said local contacts which in turn, as previously described, will cause relay R9 to be deenergized, opening the telephonic circuit between terminals 3 and at, and 5 and 6. Coincidentally with this, the armature 125 of relay R5, Fig. 4, at station A4, as previously described, will move in its indicated minus direction. Bearing in mind that relays R1 and R2 are in their normal position, relay R3, and successively its dependent relay R4, will obtain current from battery B1 to ground G1 b way of terminals c2 and 01 of relay 3 by way of contacts b3-M, and b2bl of relay R5; and contacts (11-412 of relay R1. Also, current from battery B1 will find ground by way of terminals 016 and 015 of relay B4; through contacts 04-03 to common terminal cl of relay R3; from whence it reaches ground G1 as previously traced. Signaling current from source P1 is now being applied over conductors 1p and 2;) by way of contacts 012-013-014 and c9--c110-c11 respectively serially through primary windings of repeating coil C1 by way of section terminals (Z1, (Z2, and (Z6, d5; to line terminals l and 2 inductively from secondary windings by way of section terminals (Z7, (Z8, and 0%, d3 of said repeating coil (J1, and contacts 07-08 of relay R8; also to apply signaling current across signal device D2 by way of contacts c9-cl0-c11, and 012 -013 01st of relay R4; over conductors 1 and 712; through contacts l1r-10n and 91'--8r of relay 2R; actuating said signal device accordance with code sent by key k3 at station A5, and thereby apprising the operater at jack J6, station A l, that her response is desired. Connection is then made by inserting plug as p1 into jack J6, the functiens of which operation has been described. The

operator at station A4 will lrnow the signal came from station A5 by virtue or" signal device D2 displaying and not signal device D1. It will be observed that since signaling current has been applied across line terminals 1 and 2 simultaneously with applying .it across terminals of signal device D2, all

, signal devices at stations alon line D adapted to respond to currents o the character impressed will actuate in conformance with the code displayed by the signal device D2 as described. V

Since the relay R3 must act in response to relay R5 before relay R4 can apply ringing current to the line terminals and to the auxiliary signal device D2 over jack J6, and that an appreciable element of time will elapse during the completion of this cycle of operations, currents of a momentary nature will not produce a false signaling eifect.

It will also be observed that since the armatures of relays R6 and B8 vibrate or move in response to currents of proper character being applied to them from the line, these armatures may be adapted to evidence such passage of current in an auditory or visual way, and therefore used as a signal device incidentally.

If it is desired to signal the station A4 from station A3, for instance, plug as 711 will be inserted in one of the multipled 'acks J7 and J8. Knowing the functions 0 said plug p1 the signal device D3 will be disassociated from line E by virtue of relay 4R actuating and opening its contacts 951- i 952 and g53--g54 respectively. Signaling current is then applied to the line E, at the terminals 1 and 2, station A4, by depressing rin in key 370 in conformity therewith.

a description, the relay At station A4 the signal current will find its way over conductors i5 and 4 to the signal device D1 byway of contacts 3r4 r and 5r--6r. Upon the operator at station A4 recognizing her code signal as displayed by signal device D1, she will respond by inserting plug as p1 into jack J3. The function of plug p1 being known from previous IE will actuate and disassociate signal device D1 and also allow the said operator to have telephonic access with the calling station.

If the operator at station A3, .in lieu of inserting plug as p1 into multipled jacks J8 and 'J9,-' had inserted said plug into multipled jacks J6 or J7, in lieu of actuating relay 4R, the relay 3R would be actuminals 3 and 4, an

ated thereby, not only disassociating the contacts 952 and 954 of relay 4B, and incidentally the signal device D3, by opening contacts g44g45 and 946-947 respectively of said rela 3B, but it would also disassociate the po arized relay R6, which was'connected in bridge by way of said contacts of relay 3R across terminals 3 and 4. Removing relay R6thus opens any possible circuit path to manipulatin currents between ter- 5 and 6 respectively,

7 thus making it impossible to interconnect the lines E and D remotely from either star. tions A4 or A5. r

while said contacts are close The signal being displa ed by device D1 in place of device D2, as in case before described, indicates to the operator atjack J3 that the call is coming from somewhere along line E and not from the remote line D..

There will. be no actuations of any of the relays in the associated circuits other than those specifically mentioned, nor will there be any current of a manipulating nature ap lied along the lines E or D.

n a like manner inserting a plug as p1 into jacks J12 or J13 and transmitting signal by depressing key 310, signal device '11 associated with ack J9, of Fig. 5, may

e displayed to gain the response of the.

and g59g60 respectively of said relay 5R,

6B, the relay 5R would be actuated thereby, not only disassociating the contacts g63 and 965 of relay 6R and incidentally the signal device D4 by opening the contacts 57- 58 but it would'also disassociate the relay R8, 1

which was connected in bridge by way of said contacts of relay 5R across terminals 5 and 6. Removing relay R8 thus opens any possible circuit path to manipulating currents between terminals 3 and 4, and 5 and 6 respectively, thus making it impossible to interconnect the lines E and D from either stations A4 or A5, as before.

It will be observed that by employing the common type of cordconnecting pair shown in Fig. 2, interconnection of the lines D and E at station A3 ma v be made manually by access to one of jac s J6, J7, J8, J9 and one of jacks J10, J11, J12 and J13 re-v spectively. The manual operations in such case disregard the fact that remote control switching equipment is associated.

Should operator at station A3 apply bridged signaling current along line leading to terminals 7 and 8 of station A5, relay R19, which is bridged between said terminals by way of contacts on relay 7B will correspondingly vibrate; contacts f64-f66 and f68f70 being alternately closed. Terminal 72 and spring f7 7 are applied to ground by way of contacts Isl-k2 "of relay R. Thus free pole of calling lamp 9'11 will be grounded through the windm of relay R20 Relay R20 will actuate, as well as relay R21; the latter in multiple with lamp 7'11. Relays-B21 will lock to ground on spring f77. Relay R20 has a slow release characteristic so will remain actuated during brief lapses of energizing current, as when relay R19 returns to normal position between the ringingoperating relay 7B and opening contact k1.

Thus, after the lamp y'll effects specific glowings in response to elements or" code signals, it glows permanently. As described in relation to F104, F76 may have a resistance value difi'erent than R20, so the permanent glowing can be distinguished by an intensity difi'erent than the transient glowin s.

eferring to Figs. 6 to 11 inclusive: At top of rack, member 44 is pivoted on bolts 44a and 44b and is adapted to tilt into position shown in 440, Fi 8. Said member it carries terminal rac 26 which carries twelve insulated terminals 2'5, 24, i3, i2, i1, 5e, 4e, 3e, 2e, 1e, and 6e, said terminals adapted to engage stationary insulated terminals to, 2'4, i3, 112, 2'1, i, 56', 1c", 3e", 2e",1e, 6c". The latter two sets of terminals connect directly to correspondingly designated terminals of wiring shown in Fig. 4;. Thus swinging the rocker arm 14; so its carried terminals are disengaged from their companions stationary terminals will cornpletel disassociate the relays R1, R2, R3, R4, and repeating coil C1 from the line E, Fig. 4:, but will not disassociate the jack and signal equipment shown in the lower part of Fig. 4, allowing the line E to be used normally.

42a, Fig. 8, shows the member 42 tilted outward to allow inspection of relays R3 and R4. The member 42 is. retained in normal position bygravity catch shown in three positions in Fig. 11; said catch resting against flange of angle iron 48. By depress sing outer end of catch 38 to the position 386 the member 42 can be tilted outward -on its pivots 46 and fia. 32, 30 and 34 are The apparatus consisting of frame 48 and associated equipment can be regarded as a unit and provides ready means of disassociatin skille persons. The auxiliary equipments shown in Figs. 3 and '5 may be readily mounted as specifically shown in reference to Fig. 4.

y In the foregoing specifications mention is made of the operating currents passing over the lines D and E in derivation or in parallel. These currents are superposed upon the telephonic currents during sound transmission. It is not necessary to the proper operation or manipulation of the various relays controlling the circuit relations that this derived or parallel current flow shall take place. A current applied over only one of the limbs of the lines D or E, as by opening midway or at any other point one of the limbs of either or both of said lines, or as opening of conductor at terminal g7 of relay R6, will answer all operative and manipulative conditions.

As described, Fig. 1 shows a toll circuit made up of two lines D and E adapted to be interconnected by apparatus shown in Fig. 4, at station A4. It is possible to employ additional sets as Fig. 4:, substituted for station .95, for instance, and in such case or substituting equipment by unthere would be three independent line sections adaptable to interconnection by the physical operation set forth.

It is to be understood that the present invention does not contemplate broadly the interconnection of toll lines of'the character shown herein, but is directed more particularly to improvements overan application filed by Friendly, Serial No, 34,666, June 17 1915. There are various new features in the present application and which are being claimed herein, such as the use of signaling devices displayed at the interconnection point to indicate when the lines are interconnected; further, when an operator inserts a plug in the through switching jack for connection to the far line, a signal is dis played at the controlling station of the far line to indicate that the lines are interconnected; further, meansat the intermediate interconnecting station for preventing inter connection of the lines from the other stations; further, means for rendering impossible interference with a code signal on the remote line by a remote station, that is, for example, if the operator at A4 plugs into a through switch jack as J6, and rings a station on line D, as S6,,the operator at A5 is prevented from interfering with the code ring, should she carelessly lug into a through jack J 10, because. of t e operation of relay R16; further, that signals-at interconnecting station are (and picks, can be) disassociated during through signaling and during through conversation; further, that into a throu h switching jack, as J12, provided relay 16 is at normal.

The mention of these various points of novelty is merely by way of illustration, and it is by no means exhaustive.

The term multiple in the specifications and the subjoined claims is not intended to limit or prescribe the invention to uses where any element of equipment, as a springjack or lamp ap ears in duplicate; it refers to a greater mu tiplicity,or as used sin 1y.

aving thus described our invention, what we claim as new, and desire to secure by United States Letters Patent is:

1. In apparatus for efi'ecting interconnection between line wherein currents of opposite direction are employed to efiect interconnection; a near line and station, a far or remote line and station, lamp signals at the stations, means for causin a signal to be displayed at a station on the remote line, a polarized relay bridged be: tween the conductors of the telephone line, said means being under control of aid relay, a switching cord circuit under control of the operator at the station controlling the connection, a key in the said cord circuit, and actuating currents for the relay applied by said key through a plug of said switching cord circuit inserted in the jack connected at said controlling station of the line, substantially as described.

2. In a telephone system, a first and a second line, a first station on the first line, a

v second station common to the said lines, a

polarized relay at the second station, means at the first station for controlling said p0- larized relay, a second relay controlled by said polarized relay to interconnect said lines, and a third relay bridged between the limbs of said first line, and operative to prevent the actuation of saidsecond relay.

3. In a telephone system, a first and a second line, a first station on the first line, a second station common to said lines, a polarized relay at the second tation, means at the first station for controlling said polarized relay, a second relay controlled by the polarized relay for interconnecting said lines," a third relay connected to the first line, a fourth relay connected to the other line, and normally closed contacts on said third and fourth relays included in the control circuit of said second relay.

4. In a telephone system, a firstand a econd line, a first station on the first-line, a second station common to said lines, a poof said polarized relay for interconnecting said lines, and a third relay operative over [the first line having normally closed contacts in the control circuit of thev second relay.

5. A telephone system comprising telephone lines, an interconnection point common to a first and a second line, an operators station-on each line, a first relay responsive to directlonal currents to cause the lme to be connected; sources of current,

means at one of said stations for applying current of the proper polarity to so operate said relay, a second neutral relay in a derived circuit of said first relay adapted to actuate upon current of eitherpolarity traversing it, and a signal device responsive to the actuation of said last relay.

6. At an interconnection point common to two lines adapted to be connected, a relay in a derived circuit between said lines, means whereby said relay will become actuated from current appliedfrom over said derived circuit; a signal device associated with said relay, the actuation of said relay causing the lines to become connected and cause said signal device to-actuate indicating such state. I

7. A telephone system comprising two telephone lines,- a first station on one of the two lines, a second station common to both said lines, a third station on the second of said lines,a relay at said second station adapted to interconnect said lines operative from current projected fromsaid first station, means for projecting such current, and a signal device at said thirdstation which will display during the time current causing lines to, be interconnected is acting.

8. A near and a remote line, a first station on said near line, a second station common to bothsaid lines, a third station on said remote line, a first relay at said second station in' a derived circuitbetween said lines means for applying current of prearranged character through said first relay to inter-- connect said" lines, a switching plug and spring jack, a pole-changing relay bridged between the conductors of said near line responsive to currents applied from the switching plug used to gain access to said near line throu,h the spring jack, a first signal device an second signal device at the remote station, a third relay on said remote line sensitiveto changes of current polarity adapted to cause the first signal device to to operate said pole-changing relay' and to thereupon cause the second signal device to display, and means for applying such currents. v

9. A telephone system comprising a first telephone line and a second telephone line, an interconnection point common to and interlinked with said first and said second line, a source of current, a relay responsive to directional currents from said source under control at a station on the first line, said relay adapted to cause a telephonic connection between the said lines; andmeans under control of an operator at said interconnection point to disassociate said relay from either or both lines at will.

'10. In a telephone system a springjack and a switching plug adaplted to register with the contact springs thereof; a line leading from two contact springs of said springjack; a source of ringing current adapted to be applied to said'line through said switching plug; a relay responsive to said current in a bridge between the limbs of said'line; a source of direct current, and. a pole-changing relay responsive to said first relay and adapted to alternatively apply diilerent current polarities to a conductor connected in a derived circuit of said line.

11. A telephone system comprising a telephone line, an operators station on said line, a sending station on said line, a lamp signal at the operators station, a receiving device at the operators station responsive to code signaling ringing currents from the sending station for causin said lamp to glow according to the code signal and thereafter extinguish, and automatic means for causing saidlamp to light and glow continuously after a predetermined period following the cessation of the code signaling.

12. A telephone system comprising a telephone line, an operators station on said line, a sending station on said line, a lamp signal at the operators station, a polarized relay at the operators station responsive to code signaling currents from the sending station for causing said lamp to operate according to the code signal, and a slow acting relay operative after a predetermined'period following the cessation of the code signaling for causing said lamp to glow continuously.

13. A telephone system comprising a telephone line, an operators station on said line,

a sending station on said line, a signal device at the operators station, a relay at the operators station responsive to code signaling ringing current from the sending station for causing said lamp to glow according to the code signal and thereafter extinguish, and means for automatically causing said lamp to light and glow continuously upon cessation of the code signaling. 1

' 14. A telephone system comprising a telephone line, a sending station on said line, an operators station on said line, a polarized relay connected to said line at the operators station, a signal device at the operators station, means for applying signaling current in code at the sending station for operating said relayiand lamp according to the code signal, and means responsive to the cessation of the code sig naling for automatically causing said lamp to glow continuously.

15. A telephone system comprising a telephone line, an operators station on said line, a lamp signal at the operators station, a relay at the operators station responsive to code signaling currents from the sending station for causing said lamp to operate according to the code signal, and automatic means for shifting circuit connections through said lamp responsive to the cessation of the code signalin for causing said lamp to glow continuous y.

16. A telephone system comprising a telephone line, two signal devices at a station on said line,-two sending stations on said a line, a lam signal at each signal device, a relay at eac signal device, each relay being responsive to code signaling ringing currents from one of the two sending stations for causing the corresponding lamp to 0p erate according to the code signal, and automatic means for causing said lamp to glow continuously res onsive to the cessation of the code signa ing.

17. "A telephone system comprising a tele phone line, an operators station on said line, a plurality of telephones on said line, a lamp signal at the operators station, a relay at the operators station responsive to code signaling ringing currents from any of the telephones for lighting said lamp according to the code signal and thereafter extinguishing said lamp, and automatic means ,for causing said lamp to light and glow continuously after a predetermined period following the cessationof the code signaling.

18. A telephone system comprising a telephone line, an operators station'on said line, other stations on said line, means for signaling between said other stations, means for signaling said other stations from the operators station, and means for preventing signaling said other stations from the op erators station when signaling is being effected between said other stations.

19. A telephone system comprising a telephone line, an operators station on said line, other stations on said line, a first means at said operators station controlled from one of said other stations for signal ing'a second one of saidother stations on said line, other means at said operators station of Signaling certain of said other stations, and means for rendering the said other signaling means ineflective during the operation of said first 20. A telephone system comprising telephone lines one and two connected at an in termediate interconnecting point, an oper ators station on each line, a telephone on line one between the operators stations,

v switching means at the operators station on line one controlled from the other operators station for signaling the telephone on line one, and means to prevent the o erator at the station on line one from inter ering when such signaling is being effected from her station to the telephone.

21. A telephone system comprising telehone lines one and two terminating at an intermediate interconnecting point, an operators station on each line, a telephone on line one between the operators stations, means at the operators station on line one I controlled from the other operators station for signaling the telephone on line one, and means to prevent the operator at the station on line one from interferin with signaling when signaling is being e ected from her station to the telephone.

22. A telephone system comprising a telephone line, an operators station on said line, other stations on said line, a normally disconnected jack at the operators station for said line, an operators plug ended cord circuit, a relay-responsive to the insertion of the cord plug into said jack to connect said jack and line, means at said operators station controlled from one of said other stations for signaling a second one of said other stations on said line and means for rendering said relay inefi'ective during the operation of said signaling means whereby an operator cannot interfere during the signaling. 23. In a telephone system a telephone line extending from a first operators connecting station to a second station, a second telephone line extending from the second station to a third operators connectin station, a near line jack and normally isconnected ]ack for the first line at the first operator s station, a plug ended cord circuit at said first station, and means whereby when the cord plug is connected to the switching jack said jack is connected to the first line and the first line connected through the second station to the second line, and when said cord plug is connected to the line {ack connection is established with the first ine only.

24. 'In a telephone system a telephone line extending from a first operators connecting station to a second station, a second telephone line extending from the second station to a third operators connecting station but said lines being normally disconnected at said second interconnecting station, a near line jack and a normally disconnected switching jack individual to the firstline at the first operators station, a plug ended cord circuit at the first'station, and relay mechanism at the first station and at the interconnecting station whereby when said plug is connected to the switchmg jack said ack is connected with the first line and the first line connected with the second line, and when the plug is connected to the line jack corllnection is established with the first line on 2 5 In a telephone system a telephone line extending from a'first operators connecting station to a second station, a second telephone line extending from the second station to a third operators connecting station but said lines being normally disconnected at said second interconnecting station, a near line jack and a normally disconnected switching jack individual to the first line at thefirst operators station, a plug ended cord circuit at the first station, and relay mechanism at the first station and at the interconnecting station whereby when said pin is connected to the switching jack said j ac is connected with the second line, and when the plug is connected to the line jack connection is established with the first line only, and means controlled from another station to prevent the connection of the switching jack with the line.

26. In a tele hone system, a telephone line extending rom a first operators connecting station to an intermediate station, a second telephone line extending from the intermediate station to a third operators connecting station, a near line jack and a switching jack individual to the first line at the first operators station, a plug ended cord circuit at the first station, means whereb when said plug is connected to the line jac connection is established with the first line only, a relay operated when the plug is connected to the switching 'ack to connect said jack and line, relay mec anism at the interconnectin station also responsive to the insertion o the plug in the switching jack and far lines, a near'l'ine switchingequip-- -ment and a far line switching equipment in 'dividual to the near line at its operators connecting statio'n, one of said equipments being normally disconnected, an operators plug ended cord circuit for connection to the near line switching equipment for direct connection with the near line only, means included in the far line switching equipment responsive to the connection of the op- "erators cord circuit with the far line switching equipment for connecting this last said equipment with the near line, and means responsive to the last said connection for connecting the two lines.

28. A telephone system comprising two telephone lines terminating at an intermediate interconnecting station, through and near line switching equipment associated with, an operators station on each line, means for connecting said lines together or using either line independently at the intermediate station, and means for operatively disconnecting the through switching equipment of either line responsive to a call over the corresponding line from the intermediate station.

29. A telephone system comprising two telephone lines terminating at a central interconnecting station and permanently paired thereat, an operators connecting station on each line, means whereby an operator at one station may signal the substation on the tar line, relay mechanism at the central interconnecting station controlled by the calling operator for interconnecting said lines, and a signal device at the interconnecting station operated for indicating when said lines are interconnected, and means at the intermediate station for preventing interconnection of the lines from the operators stations.

30. A telephone system comprising a telephone line extending from one operators connecting station to an intermediate exchange, a second line-from the intermediate exchange to a third operators connecting station, means whereby either operator may extend a connection to the near line or over the near line to the tar line, and a lamp signal at the tar line operated responsive to a through connection to indicate that such through connection is being efiected.

31. A telephone system comprising a telephone line extending from one operators connecting station to an intermediate exchange, a second line from the intermediate exchange to a third operators connecting station, means whereby either operator may extend a connection to the near line or over the near line to the tar line, and lamp signals at the intermediate and far line connecting stations responsive to a through connection to indicate that such through connection is being effected.

32. A telephone system comprising two telephone lines terminating at a central interconnecting station, an operator s connectin station on each line said 0 era-tors sta- T tions being at difi'erent exchanges, near line nee switching equipmentand far line switching line one between the operators statons, a calling lamp signal for each switching equipment, an operators cord circuit, and means responsive to the connection of said cord circuit with the far line switching equipment to disconnect hoth calling signal lamps.

33. A telephone system comprising two telephone lines terminating ata central inter-- connecting station and permanently paired thereat, an operators connecting station on one line, a station on the second line, means whereby the operator at the operators station may signal the station on the other line, relay mechanism at the central interconnecting station controlled by the calling operator for interconnecting said lines, a signal at the interconnecting station, and means for disconnecting the signal at the central interconnecting station'during a through connection from the operators station on the first line to the station on the other line.

34. In a telephone system a springjack, a switching plug adapted to register with the contact springs of the springjack, a line leading from the telephonic springs of the said springjack, a source of ring ing current, means "for supplying said source of ringing current through said plug in brid e of the limbs of the line, a relay responsive to said ringing current connected in bridge of the limbs of the line, a source of direct current controlled by said relay, and means for applying the said direct current over a path including a derived circuit of the line.

3,5. In a telephone system a springjack, a switching plug adapted to register with the contact springs of the springjack, a line leading from the telephonic springs of the said springjack, a source of ringing current, means for applying said source of ringing current through said plug in bridge of the limbs of the line, a relay responsive to said ringing current connected in bridge of the limbs of the line, a source of direct current controlled by said relay, and means for applying the said directcurrent over a path including a simplexed circuit of the line.

36. In a telephone system a first line arranged to be connected to a second line through connecting mechanism controlled remotely, an operators switching cord and plug, a first source of ringing current. means for connecting said plug with the first line and for operating said switching mechanism for interconnecting the lines, a relay responsive to the ringing current connected in bridge of the limbs of the first line, a second relay for applying a second source of ringing current to the second line controlledby said first relay, means for applying ringing current through the plug and across the limbs of the line in bridge, and means whereby when ringing current is applied to the first line the second relay will apply ringing current to the second line for the period of said application of ringing current to the first line.

37. In a telephone system a first line arranged to be connected to a second'line through connecting mechanism controlled remotely, an operators switching cord and plug, a source of alternating current, means for connecting said plug with the first line and for operating said switching mechanism for interconnecting the lines, a relay responsive to alternating current connected in bridge ofthe limbs of the first line, a second relay for applying ringing current to the second line controlled by said first relay over an operating conductor, means for applying the source of ringing current through the plug and in bridge of the limbs of the first line, and means whereby when the ringing current is applied to the first line the second relay will apply ringing current to the second line for the period of said application of ringing current to the first line.

38. In a telephone system a springjack,

' a switching plug adapted to register with the cooperating second line,

contact springs of the springjack, a line leading from the said springjack, a source of ringing current, means for applying said source of ringingcurrent through the plug in bridge of the limbs of the line, a relay responsive to said ringing current connected in bridge of the limbs of the line, two sources of direct current controlled by said relay, a second relay differently responsive to the said two current sources; and means whereby when the first said relay operates the said second relay will be caused to correspondingly operate.

39. In a telephone system a springjaclr, a switching plug adapted to register with the contact springs of the springjack, a line leading from the said springjack, a source of alternating current, means for applying said source of alternating current through theplug in bridge-oi the limbs of the line, a relay responsive to said alternating current connected in bridge of the limbs of the line, two sources of direct current controlled by said relay, a second relay difierently responsive to the said two current sources, and means whereby when the first said relay operates the said second relay will be caused to correspondingly operate.

-d0. In a telephone system a trunk line and an electromagnetic device on the second line, a first relay responsive to ringing current connected in bridge of the telephonic limbs of the trunk, a source of ringing current. and means for applying it in bridge of the telephonic limbs of the trunk to operate the said first relay, a second source of ringing current and a means including a second relay for applying the said current to the second line, a control circuit intermediate of the first relay and the second relay including talking conductors of the trunk line whereby when the first source of ringing current is applied to operate the first relay the said second relay will be caused to apply ringing current along the second line to operate the said signal device.

41. In a telephone system a trunk line and a cooperating second line, a first relay re.- sponsive to ringing current in bridge of the telephonic limbs of the trunk, a source of ringing current and means for applying it in bridge of the telephonic limbs of the trunk to operate the said first relay, a second source of ringing current and means including a second relay for applying it to the second line, a control circuit intermediate of the first relay and the second talking conductors of the trunk line whereby when the first source of ringing current is applied to operate the first relay the said second relay will be caused to apply ringing current along the second line, and a means to disassociate the trunk line from the second line telephonically for the duration of the application. of the said first source of ringing current to operate the first said relay.

42. In a telephone system a trunk line and a means controlled over an operating circuit from a station connected to the trunk for causing the trunk to be connected with a second line, a source of ringing current and means for applying it in bridge of the limbs of the trunk, a relay responsive to the ringing current connected in bridge of the limbs of the trunk, a second'source of ringing current and a second relay connected to a talking conductorof the second line for effecting the application of said second source to said second line wherebywhen the'first said ringing current is applied to operate the first said relay the second said relay will cause the said second source of ringing current to he applied along the said second line for the duration of the application of the signaling pnrrentin bridge of the limbs of the trunk 43. In a telephone system a calling switching plug and cord, a called line, a trunk line, a springjack for connecting the switching plug to the trunk line, means controlled from the calling end of the trunk for connecting the trunk to the called line, operator controlled means for applying ringing current to the trunk from the calling end, a second source of ringing current for application to the called line, and repeating relays progressively controlled over successive portions of the talking conductors responsive to relay including the operator controlled means'whereby when called line, an operator controlled link connecting said lines, means controlled by the operator for applying ringing current to the calling line end of the link, a second source of ringing current for application to the called line, and repeating ,r'elays progressively controlled over successive portions of the talking conductors responsive to the operator controlled ringing current for applying the second source of ringing current to the called line. i p I 45. In a telephone system, a first, a second and a third line, means for connecting the first and second and the second and third lines together, a signal device on the third line, a source of ringing current and means for applying it in bridge of the talking limbs of the first line, a relay in bridge of the talking limbs of the first line responsive to the said ringing current, a second relay connected to the talking limbs of the second line which will operate responsive to current controlled by the operation of the first relay, an additional source of ringing current and means controlled by the second relay for applying it to the third line whereupon applying the signaling current to the first line will cause an independent source of ringing current to be applied to the third line to operate the sigma device thereon.

46. In a telephone system a first, a second and a third line, means for connecting them for telephonic service from the first to and including the third line, a calling station on the first line, an electromagnet device on the third line, a source of ringing current and means for applying it in bridge of the talking limbs of the first line, a relay in bridge of the talking limbs of the first line responsive to the said ringing current, a second relay connected to the talking limbs of the second line operative responsive to current controlled by the operation of the first relay,

an additional source of ringing current and means controlled by the second relay for applying the latter source of ringing current to the third line, whereupon applying the signaling current to the first line will cause said additional source of ringing current to be applied to the third line to operate the electromagnetic device thereon.

47. In a telephone system a first, a second and a third line, means for connecting them for telephonic service from the first to and including the third line, signal devices on the second and the third lines, a source of ringing current and means for applying it in bridge of the talking limbs of the first line, a first relay in bridge of the talking limbs of the first line responsive to the said ringing current, means responsive to the first relay when actuated by the application of ringing current to the first line to apply ringing,

current to the third line to operate the signal device thereon and operatively disassociate the signal from the second line.

Signed by us at Portland, county of Multnomah, and State of Oregon, in the presence of two Witnesses, this 22nd day of May, 1915.

HERBERT M. FRIENDLY. ARCHIBALD E. BURNS. Witnesses:

M. L. KNAPP, Soorrr Bozonrn.

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