US1267131A - Automatic or semi-automatic telephone system. - Google Patents

Description

A. B. SMITH AUTOMATIC 0R semmummmc TELEPHONE SYSTEM. un/mo" FILED mmzs. I914.

1 ,267, 1 31 atented May 21,1918.

5 SHEETS-SHEET l.

Q Q m Y? m mg WT/YEISSES Z VVE/VTOR- M a) W A. B. SMHH.

AUTOMATIC OR SEMI-AUTOMATIC TELEPHONE SYSTEM.

lW/Tzvbs a 4M w- 12% 1 1f um/c MM;

AP LICATION FfLEU MAFLZS I914 :[EEMW Patented May 21, 1918.

5 SHEEISSHEET 2.

A. B. SMITH. AUTOMATIC 0R SEMI-AUTOMATIC TELEPHONE SYSTEM. APPUCATIUN HLEU' MAR- 25. l9l4.

5 SHEEIS-SVHEIIIT 3.

O Q JQ 4 I/V/TNESSES MGR Az'rHuz 5. 5M1TH Patented May 21, 1918.

A. B. SMITH.

AUTOMATIC 0R SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPUCATIDN HLED MAR. 2512914.

Patented May 21, 1918.

5 SHiEIS- SHEET 4.

XVI/:2 21 705".- AETHUE 5 5M! TH Ma m- AUTOMA IC 0R SEMLAUTOMAHC TELEPHONE SYSTEM.

APPLICAHON EILED MAR. 25. 19:4 1,267,131.

Patented May 21', 1918 5 SHEETS-SHEET 5.

V/T/VESSES' Mid M UNITED STATES PATENT OFFICE.

ARTHUR BESSEY SMITH, OF EVANSTON, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC OR SEMI-AUTOMATIC TELEPHONE SYSTEM.

Application filed March 25,

To all whom it may concern:

llo it known that I, Ann-Inn Basso!" b'ilrrn. a citizen of tho [initcd States of America. and resident of Evanston, Cook county, Illinois. ha vo invcnted certain now and useful lnun'omnlcnts in Automatic or Semi Automatic 'lclcphonc Systems, of which the following is a sl'iecification.

My invention relates to in'iprovemonts in automatic or semi-automatic telephone systoms and has for its object the provision of such a system in which phantom circuit (a employed for establishing connections llerelolore attempt has been made to use phantom circuits in telephone. systems, but in every instance, as; fa as I am aware, the plrvsieal circuits on which the phantom cirrail is slum-imposed have been used only for establi hing manual connections, but I believe that Illlil the first, to employ these physical circuits for tho purpose o'lf establishing a call through automatic switches, In order to accomplish this it is necessary that that part of the physical circuits on which the phantom circuit is superimposed shouid he insulated from the rest of the physical circuits in order to prevcnt any interhu'encc with the phantom circuit.

A feature of my invention, therefore, rclates to this insulation of that part of the physical circuit which is employed by the phantom circuit. together with the provision of means whereby a call can ho inadc auto lnatieallv over such a physical circuit williout interfering in any way with tho phantom circuit. The phantom circuit can he employed either in commotion with a call which is established autonulticalljl', or with a call which is established manually, al though I have shown specific neans where-- by this phantom circuit can be employed in an automatic call. Likewise the connection can he made to the physical circuit cithcr illitOlllfli-i f i Q or through an opcrators manual board.

These and other features and objects of my invention will. he more readily understood by reference, to the accompanying drawings, in which I have illustrated my invention in connection with certain specific means for extending a connection to and from the physical circuits and the phantom circuit of the trunk. As illustrated. those means involye automatic switches of well.- known types, and as the specific form of Specification of Letters Patent.

Patented May 21, 1918.

1914. Srial No. 827,063.

theso switches which are employed for extending the connection to and from this trunk line forms no part of my present in vention. and as these switches are fully doscribcd in the publications and patents hero inaftcr referred to, a detailed description of these various switches will not be given, except in so far as is necessary for a clear understanding of the various features of my invention.

In the drawings, Figures 1 to 7, inclusive, are diagranunatic representations of a cireuit (Ulllltfitlnll established between a call ing: subscriber in Fig. 1 of one exchange and a called sul'iscriher in Fig. 7 at another oxchange in a system embodying the features of l\] invent'iml. Fig. 8 shows the mechanical details; and construction of a polarized relay with modifications which may be used in connection with my system at 49, 73. etc. for repeatingimpulses ov er the physical eii. euit.

Figs. 1 and 2 taken together represent; up paratus at the first said exchange. There is herein shown a subscribcrs substation A, the lino conductors of which terminate in an individual or line switch C. The line sw-iteh shown at (l is one of a group of similar lino switches, the plungers (not shown} of which engage a shaft and are controlled by the operation ofthe master switch D in sueh a manner that they are, when in normal position, held directly in front of the terminals of a trunk line leading to a seleclor F. Certain levels of the said selector hanks contain trunk lines which lead through a group of relays M over the trunk lines to the internu-diate exehangc. It i:= of course. understood that'certain other levels of said selector banks may lead to various other apparatus in said exchange for cou1 pletingz connections within said exchange.

l igsQZl. 4 and 5 taken together represent apparatus at the intermediatc or second exchange. It will, of course, he understood that the subscribers substations of this taxehangrc may he of any type "whatsoevt-rr and that the said exchange contains the necessary apparatus (not shown) for completing; connections within the exchange. The relays N form'the connecting link between the trunk lilies leading from the first said exchange to the selector F in the second ex change. (crtain levels of the said selector,

hanks terminate in groups of relays K,

i Ct,

which in turn connect with answering jacks the said jacks being located in a manual board in said exchange. The said manual board contains, together with other apparatus, the cord circuits (Y). which cord circuits are adapted for extending connection from jacks j tojacks The said jacks are the terminals of the conductors leading to a group of relays Q (Fig. 5), which relays are connected to trunk lines leading to a.

third exchange. shown in Figs. 6 and 7. The 7 function of the repeaters I (Fig. will be hereinafter explained.

Figs. 6 and 7 taken together represent apparatus in the third-mentioned exchange. It is. of course, understood that the subscribers substatitms of said exchange, as in the above case. may be of any type whatsoever and that the said exchange contains the necessary apparatus (not shown) for con pleting connection within the exchange. The group of relays J (Fig. l) form the connecting; link l'ietween the trunk lines leading from the said second exchange to the connector H in the'lbird exchange. The said connector switches complete the connection to the called substation through the medium of the line switch Figs. 2 and 3 taken together represent three trunk lines connecting the first said exchange with the second exchange. two of the said trunk lines being what are known as physical circuit trunk lines. while the third trunk line is known as a phantom circuit trunk line.

Figs. 5 and 6 taken together represent three trunk lines connecting the aforesaid second exchange with the. third exchange. Two of the said trunk lines. like in the above-mentioned case, are what are known as physical circuit trunk lines. while the third trunk line is what is known as a phantom circuit trunk line.

While in these drawings I have indicated the trunk lines terminating in one certain type of automatic switch. it will. of course. be understood that in ordinary practice. suitable Selector switches may be inserted throughout the system without departing from the l'n'inciples oi my invention. For example: Referring to Fig. 7. instead of connecting the trunk linc Sit--81 directly to the connector switch H. a suitable selector or a. plurality of selector switches. similar to the selector E. may 'be inserted between the trunk line 8(l-8l and the connector switch H.

'lhere isshown throughout the drawings a plurality of batteries. namely B. B and B", each having one terminal grounded at (l. Each excha go is shown provided with one of said bstttries .for supplying current for operating the central otiiee equipment and for furnishing talking current. There is likewise shown a plurality of batteries B,

B and I. These are preferably double voltage batteries. in, their voltage is higher than the voltage. of the be'forc-inenlioned batteries. The use of these batteries will hereinafter be explained.

The automatic substations A and A may he of any suitable or ap n-ovcd type. lieferring to the substation A. as herein shown it comprises the usual receiyer l, transmitter 3, SWltt'LJUOli 4., ringer 5 and condenser (7. Being an automatic substation. it is also PI'OVldcd with an impulse transmitter or calling device which is re )rcsented herein by a pair of impulse springs 7 and 8 and an impulse. wheel J, which latter is assumed to be controlled through the medium oi a finger hole dial (N t shown) in such a main ner that the imprise springs 7 and H may be momentarily separated a number of times corresponding to the digit called.

The sulnscriber's individual sw itch is of the general type of subscribefs switch shown in. liritish patent. to R. \V. James No. 26.301 of 1906, being, however. of the particular type disclosed in British patent to '1. (1. Martin No. 1419 of 1910. This line switch comprises. among other details. a plunger (not shonn) attached to the end of the so called plunger arin l (l. which is controlled by the magnet 11. lhe magnet 11 comprises four windings. namely. a pull-down winding 12, a cut-oil or holding winding 12 a line winding 14. and an auxiliary or holding winding 15. The core of the magnet 10 is so constructed that the magnetic circuit o!' the windings 12 and 13 is sepaate from that of the windings 1i and 1:"). The winding 12 operates both the plunger arm 10 and the armature 16, while the winding 13 is only strong enough to operate the cnhotl' armature 1,6 and to hold the plunger arm 10 in its operated position. When the plunger arm 10 is operated, the plunger is forced into a bank of contact springs, forcing the Springs 1. 18. 19 and 20 into engagement with the springs 21, 22. 23 and 24. respectively. Although only one set of springs (1724.) is shown. each line switch is provided. with a plurality of such sets. each set, forming the terminal of a trunk line leading to the selector E. llach trunk line is connected in multiple with the corresponding springs of all the line. switches oi the group which is-controlledby the master switch l). The switch (l is controlled by the subscriber through the medium of the line relay M, as will be hereinafter more fully explained.

The master switch I) is of the general type disclosed in British Patent No. 26.301 of 1906. hercinabove referred to. being. however, of the particular type disclosed in said British Patent No. 1419 of 1910. The tunc tion of the master switch. as is well known. is to maintain the plungcrs of all the idle line witches in pmition to engage the terminals of an idle trunk line.

The aeleetor switch F. is of the general type ol selector switch (list'losed in linited t tzttes l miter latent Xo. M55321, granted Ma eh -l. ltllhi to Keith. lirh'rhmn and lilllltr-lfllh except that the so-called Hide eu'itrh ii omitted and the eireuite are modi tied to adapt the mitt-h to operate in a system in whirl] it s eontrolled h impulse: delivered over two sides of the line in writ-s in the manner sheu'n in British Pat ent Xo. W517? of .1913. granted to T. (l, Martin. Among other details. the selector ll comprises a hank of contacts arranged in horizontal rows or level whi 'h eontacts are adapted to he engaged h a set of wipers it; and 27 carried upon a Shaft (not vshown) which has a vertical movement controlled lJ the vertical magnet and a rotary movement controlled by the rotary magnet 21 The operations of \ariote: parts of the wilt-h are etmtrolled through the. medium oi. a douhle-Wound line relay l". .lleann for permitting" the 4\\'llfjli to he rei-tored to normal po ition are provided in the release magnet ill, which. upon each giving. it ithdrawa lite retainin; pupils from the hatt. The springs 32 and 11 3 close out when the szuitrh shaft ha: been raised one or more steps from its lowest position. The relays 34- and 35 are slow acting: relaythat is, the de'energize slowly after their en: rg'izing circuits are broken.

Jhe group of relays M (Fig. 2) ('onneet "the hank terminals 36, 37 and 35% of the.

selector E with the trunk line 39--40. The battery B is bridged across the conductors 41-43 through the windings ot the slow acting; polarized relay t-7'in series with the windings 44 and 4.5 of the repeating coil S. The impulses of current, transmitted through the windings 44 and l-5 of the re pcating; coil due to the momentary separation of the impulse springs 7 and d of the substation. 1L operate to induee iinpulnes of current in the windings 4 7* and 45 of the said repeating coil S. The said induced im pulses extend from the point 69 through the Winding 46 of the repeating eoil S, over the trunk conductor 40, windings 51 and 50 of the repeating coil S in series with the polarized relay 49, over the return condue tor 39 and through the Winding 47 of the. repeating coil S back to the starting" point. The polarized relay 49 is constructed with tivo'separate armaturefi, namely, 54- and 55. It is well known that an impulse of current igenerated-in the secondary of an inducton coil when a circuit is established in he primary as well as when thocircutl, hroken, l'loweyer, it is alklo tvell known tilmf the circuit through the prnnary of the safe coil may he o arranged with regard to resi tance and. voltage that this impulse which the circuit is broken.

in induced in the secondary when the primary circuit is estahlished lH either st rongrcr or weaker than that whieh is indueed when Therefore. in my syn-- tom in Whieh the impulse on the hrealr alone is utilized the primal"; circuit in so arranged that the impulse induced when the circuit la estahlis'hed in the weaker and the arlnaturea oi the polarized relay l9 may he easily adjusted no that this weaker impul e will not :ill'eet them. The armature 5-l responds lo in'tpulses of eat-rent transmitted through the relay ll in one direetiou. and the armature 5:3 respond to the impiIl e il'ttltfill'tlll'ttl through the relay 49 in the op posite, direet ion. The mid relay -l-5l is so eonntrueted and adjueted 2H not to respond to butter;' current over the phantom circuit trunk line. lhe relays i7 and eontrol the operation of the switches loeat'ed in the intermediate exehang't'n 'l'he relays tit and (3; control the application of halter from the high voltage hatter It to the eondur lors -11 and ill for releasing purpooes. \\'lll('ll ill he ln-reinal'ler more l'ull explained. The operation of the uroupa ol relays M and N of the truulc line oz: t'll is similar to th operation of the groups ol rela \I and N of the trunl-z line I!t-lll. lhe eonduetors Git" and t3?) and lit} and ti? are the phantom taps of th trunk linen aw- -l0 and oIr tS-i. 1 preferably join thepoinn tlS--t3tl and 7tl71 of the repeatin; (oils h and S thus Fhort-eireuiting the polarized relays l8 and 72. i'esl'iectirelv. in it is well known h those versed in the art that there is not am dilierenee of potential lietneeu corresponding points on the two conductors forming one limb of the phantom circuit. the halanee of my phantom eircuit in not afi'eet'ed h\' eonnecting said points together. and the resistance. of each of in}: physical circuits in somewhat decreased, thus giving stronger indueed impulses to operate the arn'tatureg of the polarized relays 49 and T -L l'thptfllll'tflk.

lhe repeater l is adapted to reeeive iiiipulses from the enlist'atlon and to repeat them over the phantom trunk line to a seeonrl exchange. i-\n'ion,Q; "therdetails, it comprises a double-wound line rela) T4 and the slow acting" relays and Ttl The slow aet ing relay 'itl oi'ierates to eat the eondensers :57 and 78 out of circuit While the repeater 18 operating to repeat. impulses to the said seeoud exehange.

The selector F is Similar in all respects to the selector 1).

The device K eonsists ot' a p'luralitr ol relays! together with tho uaual line Kl QHitl lamp 7!) and answering jack j.

The cord eireuit O is provided nith the usual supervisory signal 82 and the tlt't'th' sary relays for controlling the same. When the key K is operated, the slow acting relay R2 operates t tran mit an impulse of eurrent over the conductors 84; and 85. The function of said preliminary impulse of current will he hereinafter explained.

The trunk lines 8(i87 and 88-89 (Figs. 5 and (i) are similar to the trunk lines ink-t0 and (i3--(3l, except that they are arranged to be seized manually, (a, by means of a plug and jack, instead of by an automatic switch. It will also be seen that the trunk line Sit--87 is arranged for extending a connection in one direction. while the trunk line 88--89 is arranged for extending a connection in the opposite direction. The conductors 90 and 9t and 9; and 93 form the phantom taps oi' the trunk lines St --87 and 89-39, as in the irevious case.

The connector H (Fig. 7) is oi the same eneral type of connector disclosed in United States Letters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson and Erickson, the circuits, however, being n'ioditied to adapt the switch to operate in a systent in which the central otiice apparatus is controlled by impulses delivered over the two sides of the line in series. Like the lectors. the connector is provided with a shaft (not shown) carrying the wipers 9t, 95 and 90, which shaft is controlled by the vertical magnet 97 and the rotary magnet 98. The usual side switch comprising the wipers 10], 10-2, .103 and 101- is controlled by the private magnet 105 in the usual well-known manner. The magnet 106 is the usual release magnet. The line relay 107 is connected to the line conductors 80 and 81. The so called back-bridge relay 108 provides tallc ing battery current for the called substation. The ringing relay 109 is the mean dhrou h which ringing current applied to tie called line. The busy signaling machine It, as herein represented, comprises an induction coil or transformer, the primary winding of which is included in a local circuit with a battery and two interrnpters, one of high frequency and one of low frequency. Through the medium of these interrupters an intermittent interrupted current is sup plied to the primary winding, which induces an intermittent alternating current in the secondary Winding, whereby when said winding is connected with the subscribers line an intermittent buzzing sound is heard in the receiver.

The substation A and the line switch C are similar in all respects to the substation A and the line switch C.

A general description of the apparatus having been given, it will now be explained how a connection is extended from a calling substation A, whose lines terminate in one exchange, to it called. substation A, whose lines terminate in another exchange, the counectien extending through an intermediate exchange. We will assume that the calling subscriber A must call the number 22 to ob tain connection with the operator at the ins, tcrnlcdiatc exchange.

Upon the renuhal ot' the receiver from the switch-hook at the substation A preparatory to making a call, an energizing circuit is closed through the line winding 14 of the hulividual switch C, thereby attract;- iug the line armature 1.10. he armature 1.10, upon being attracted, a circuit, through the pulhdmrn coil 12in series with the auxiliary winding 15. The pull-down coil, u )11 energizing, attracts the plunger arm 10 to force the plunger into the bank of sprin ]7---24, inclusive. it also operates the t-otf armature 16, thereby di onnecting the line winding l-t from the ine.

The armature 110 does not (all back immediately, hrwverer, owing to the fact that the wil'iding 15 is still in series with the pulldown winding 1:2. Upon the plunger? arm in being attracted. the springs 111 and 112 are brought. together to short-circuit the auxiliary winding 15, mating the same slightly w acting. The armature 111') licing set: to fall back allows sutiicient time for a holding circuit to be closed in tie switch ahead for the cut-off or holding winding in. The engagement of the springs 17 and 20 wizl the springs 21 and 24, respectively, extei is the subscribers lines to the 95 line relay 3b of the selector i The line relay 30 of the selector switch E is thereupon energized. closing a circuit through the relay 3 The relay 34, upon energizing, closes the ahoveanentioned holding circuit through the cut-o'fi winding 13 of the line switch (I. This circuit extends tron: ground. G through the springs 113. bank springs 2:3 and 1.8 and the cut-oi? winding 13 to the battery, lead 100, thence through battery B to ground G. The winding 13. upon energizing, holds the armature 16 and the plunger arm 10 in their operated positions after the circuit of the Hill-down winding is broken by the falling back of the line a rnia'iu re 1'10 A guarditig ground potential is suppiied to the cornice tor private bank contacts of the calling line as soon as the relay 34 is energized. This circuit extends over the circuit 3ust traced to the bank spring 18, thence over the trim]; 114 to said private bank contact. The eiiergization of the relay 34 also prepares euit for the rertical magnet by bringing into engagement the springs 115 and 116 and opens the circuit of the rel ease magnet at the springs 116 and 117.

The calling subscriber now operates his calling device for the first digit 2, whereby the substation impulse springs 7 and 8 are operated twice momentarily, each time breaking the circuit of the selector line relay 30. The relay 34 of the selector being slow acting does not deenergize during thcmom'entary interruptions of its circuit by the line relay 30,

.deiinergizes, an impulse is transmitted over the circuit extending from ground G through the contact of springs 119 and 118, springs 121 of the relay 1:32, springs 116 and 1 15 of the relay relay 13 and the vertical magnet 28 to the battery lead .100. The vertical magnet receives live impulses of rurrent over this circuit and operates to raise the switch shaft and wipers two steps to a position opposite the second row or level of hank contacts. The oii-noruull springs fl) and 33 close as soon as the shaft is raised one step, but the circuit of the release magnet 31 still remains open at the springs 116 and 11.7. The slow acting relay is maintuined in its energized position while impulses are being sent through it to the vertical magnet, and in its energized position closes a circuit extending from ground Gr through the springs 123 and 124 and the relay 126 to the battery lead 100. The relay 1217, upon energizing, closes a locking circuit for itself extending from ground G at the relay 1 1 through the springs 113, rotary uuignel springs 129 and 128, normal springs 33 and the springs 130 and 131 of the relay 1%, thence through the said relay 126 to the battery lead 100. Thus, upon the deenergization oi": the relay 35 after the last impulse delivered to the vertical magnet, the relay 126 remains energized and the circuit of the rotary magnet is closed. This circuit cxtendslfrom ground G through .thesprings 113, springs 129 and 128, normal springs 33, springs 130 and 131, springs 124 and 1.25, 111-- terrupter springs 127 and the rotary magnet 29 to the battery lead 100. The rotary magnet, upon energizing, rotates the wipers one step and, by opening the springs 128 and 129, disconnects ground (1 from itself and the relay 12b. If the first trunk line of the second level is idle, the relay 126 decnergizes as soon as the springs 128 and 129 are opened. If this trunk line. is busy, however, the private wiper 26 finds the contact with which it engages provided with a guarding ground potential, which is transmitted to the relay 126 through the springs 130 and 131, thereby preventing itfrom deiinergizing. The rotary magnet, however, denengizes when the springs 127 separate, regard.- less of Whether the relay 126 remains energized or not. If the relay 126 remains energized, the circuit of the rotary magnet will heagain closed as soon as the armature drops hack far enough to close the springs 128 and 129. The rotary magnet will therefore operate in the manner of a buzzer to advance the wipers step by step over the contacts until the non-grounded contact of an idle trunk line is reached by the wiper 26, whereupon the relay 126 dei uergizes. The relay 1%, upon dei nerg'iziii whether after one or several operations of the rotary magi'nct, permanently breaks the circuit of the magnet 29 and closes the circuit of the switching relay 122. The circuit through Said relay 122 extends from ground G through the springs 113.S|)Il11;1s 129 and 12S, springs 33, springs 13(1 and 132 and the relay 122 to the battery lead 100. The relay 122, upon energizing" disconnects the line relay 3!) from the line and extends the line connection over the heavy conductors through the wipers 25 and 27 to the group of relays M (Fig. 2) of the trunk line ill--10. The wipcr25 and 21' making: contact with the conductors 41 and 4-3, r(2s 'iectii'ely, close a circuit through the line relay 4-7, the said cirruii extending from ground G through the lower winding of the relay 17, Winding 45 of the repeatingcoil S, springs 133 and 131 of the relay 56, the lower winding of said relay. conductor 43, Wiper 27, over the hen vy eonillu-lors, through the substation A, over the heavy return conductor, wiper :55, conductor 11. winding 44; of the repeating coil S and the upper winding of the relay 4? to the battery B. The relay 47, upon energizing, provides a holding circuit for the relay 12 of the selector E and the winding 1b of the line switch 1. The said circuit for the relay 122 of the lertor E extends from ground G through the contact of springs 13?, conductor "12, Wiper 26, springs 130 and 132 and the relay 122 to the battery lead 100. The holding circuit for the Winding 13 extends over the above-traccd circuit through the wiper 26,

(iii-normal springs 33, springs 128 and 129, bani? springs 2 and 18 and. through the winding 13 to the battery lead 100. A further result the energization of the relay 47 is to closean ener izin circuit thron -h the relays 61 and 62. The said circuit extends from ground G through the springs 135 and the relays G1 and (12 to the battery B.

The relay 61 energizinp quicker than the relay 62 opens the contacts of its springs 138 and 131) before the relay G2 closes its contact springs .140 and 141. Therefore the energization of said relays is functionless at this time. The relay 56, upon energizing, completes a locking circuit for itself through the springs 136 independent of its energiz ing circuit. A further result due to the energization of said relay 56 is to momentarily open the energizing circuit of the relay 4? at the springs 13 and 133, and then to again close said circuit at the springs 133 and 137, thus connecting the conductor 13 direct to one terminal of the Winding 45 of the repeating coil The said operation of the relay 56 transmits one impulse of cur rent through the windings 45 and 44 of the repeating coil S, which impulse of current induces a corresponding impulse of current in the secondary windings 46 and 47 of said The induced impulse exrepeating coil. tends from the point 69 through the winding 16 of the repeating coil S, trunk conductor 40. Winding 51 of" tho ropunt-ing ruil S, polnrizoil relay -49, winding 50 of tho repeating roil S. trunk rontluctor 39 and the winding 4? of tho ropuating roil 9 hack to the point till. 'lho arniuturo fi-t of tho pulnrizrd rulay 4t responds to suitl llllPlllHt illltl. rloson u cir- ('llil through the rolnys 57 and 38. The billtl oirvuit; tor the relay 57 oxtomls from ground i through tho rontartr of prings 'l 12. springs I44 and ll-i'l and tho rt-hiy 57 to tho lmttrry lrzul 200. Thu roluy 57. upon (nor-- gi'liing, UltlStS 2i lurking ou-ruit for itself through tho springs H5 uiul llil intlupmuh out of its energizing: rirruit. A l'urthor result of the rnrrgimlion of snhl rolay is to rlosu n bridge across the t'tilltlHtiOl'H 5!) and 60, thus vnrrgizinyr tlulino rt-lny 1 18 of tho solortor 1*. Thu suiil vnvrgizing rirruit on tennis from ground ti (Fig: t) through tho lowor winding of tho lino roluy 148., springs H9 ulul M9 of tho rolay 151. trunl; routluotor till, winding; 523 of tho rupvutin; coil S, springs Ht. springs l t-7. Winding 5; of tho repeating coil 2 trunk rmulnrlor it". springs I50 uml la'itl" of tho. ri-luy l-il uiul tho upper wintling ol the rvluy t lt; to tho hutlrry lriul 2 'lhr apparatus: is. now in rrzulinrsu for tho opvrution of tho *lih'tl at tho culling Hlllislutiml for the u 1ontl digit J.

The o'|u .r:1tion of tho walling tlt'Yit't. for tho second digit 1 opons tlueurrgizing rirunit, of the relay 1:7 twiro, hut us tho suiil rrluy is slow noting it; (low; not, (luinorgizu during the momentary intnrruption of its circuit at the substation. lhrrphy prurmuiu tho first selector l'l tllltl tho lino switch (i from releasing. Thu opuning vand 1'lt).'--ill; of tho said iinpulso springs at the sni'istiuion causes the windings 4t and 15 of tho rcpt-at ing ooil S to inrluoo impulsvn of rurrmli in the secondary windings t7 mul it'- of mint repoatin coil The arumturu 54- ol tho )Olfll'lZBt. relay 49 mspoinliug to mill ill- (luccd impulses oporutos to ropvut the mid. impulses to tho rrlay 5% over u rir uil ex tending from ground (2" through tin: routact of springs H23 and the rvluy on to tlu: buttery lead 200. The rrlny 58 rouponiling to said impulses repeats the. sumo to the line relay 148 of the. selector F. Thu operations of the selector F that; are brought, about by the line relay 148 are similar in all. resperts to the operations of the first olootor ll. Tho selector F, upon being thus oprrntml. (XllOl'lt'lS the lino connection to the group of relays K. The roluy 152 of the said group of relays thereupon becomes energized and closes n. holding circuit for the relay 1.531 of the selector F and also causes tho linr lump 79 to glow. The holding rircuit For the said relay 151 oxtr-nds from ground G" through tho contact of springs 153 and, 154. wiper 156, contact of springs 157 untl 15S and tho relay 151 to tho buttery lead 300.

The operator at the manual board not-i0 lug: tho lamp 7U glowin g inserts the plug {2' ol tho. oortl circuit. 0 into the inch 1 P e insertion of the plug p into the jack j rnusrs thr rrluys 159. 166 and 165 to enorgino. Tho energizing circuit for the relay 159 extends from ground G through the contacts of tho nprings 160 and the reluy 159 to tho hntxtrry lozul 200. The relay 159, upon rnorgizin opurntou to close a new holding rirrnit for tho ruluy 151 of the selector F and to (liHCflllHNfl l'llu uoinlurtors 161. unit 162 from tlulino roluy 15; uml to connect the Fittitl ('tllllllltiltll'h with tho jnrk spring; 163 nlltl Iii-t. rrspm-tivrl The energizing cirt'uil. 'l'or tho roluy ltltt tXlt'IltlS l'roni grountl tl through tho .-':|i l rrluy. slrrvo ol" tho jack j and tho lHIHll'lHg of tho plug: p to tho lmttory lriul .Ztlt), 'lhr rrluy 166, upon out-ruining. t wrutr,-. to rlosr u rirouit' through tho springs Hi? to inur'r lhr lump 82 to glow. hut the Stiltl rirruit in iunurtliutoly opened at tho spring ms hy tho rnorgizatiou of tho ruin ltih. 'l'hp )|)iltlltll' now oporatrs thr lu-y it" to ln-iilgr lu-r talking not :ioross thilino rotulurlors lil :uul litl guu'l rvrvivrs the, rolling ulnz-wiln-r! ll'tltl. l pon learning that tho uulN-rilwr :il uhstntion whoso lino ltllllillttltH in u tlistunt oxrhnugo, is \tllllll'tl. sho insrrb tin plu; p into tho jnrk j. \Vo will :lfifilllllt that tho rullwl suhslnlion's number i it). 'lhr inurrtion of the plug 1 into tho jnvk j onuuw thirrluys 171 illltl 172 (Fig. (I) to onvrgzizo on" :1 rirruituxtvruling' from ground ti through tluslttYt ol' the pin" p. hushiun' of tin jurh 10G nlul thr rulnyh lit and lit! in Stllt'R to thilmttvry ll. 'lhr rni-rgizntiou ol illtl rrluys is llllltlllUllltHH ll this llitlt'. Thu tlllt'l'ill l l\n\\ throws tho kor K. hritlfling' lltl milling ll\'i ,'t' 172i tilfl'nSr tho ((llltlllt'ltll'i-t 9i unil thus rn rp izing tlw rrluy H 5. 'lho rvlny 5 23 upon onvrn'ixingr. ttilll'llt'ltS :i lurking cirvnit for itsoll through tho sprin w li'l pontlrut of its rnorgiviing i-rrni ("on 'a oprrzlt s to transmit. our impulse of current (Wtl' tho fitmtliltlfll' S2, inul 8+ in tho sunw inunnrr as tho rrlay ht: (Fig. 2') operated in tho provious instanro. 'llnsaid llllplllSt of rurrent (xii-nth from ground ti" through tlw wintling 17? of tho ropouting coil S over lhr uonilurtur 95. through tho ('Ol'tl rirruit. 0. orvr thr return ronilurtor S4 uiul winding 176 of tho rrpouti-ngrroil S" to liuttrry B. This ilnpulw o'l rurrrnt llltlllttS .n rorrvs iontlin gimpulse of rurront in tho windings 12 'l T :nul 178 of snirl rrpruting roil S, 'lhr llltllltlt'l iinpulsr tXl'tHtlS from tho point 180 through tho winding 178 of tho rvprutiug roil P (wonillu'tor R7, winding l' l of tho rcprutingrroil S. polarizoil relay i l-1. winding 1 5 182 of the l'QXiltillg (-oil S. ('ontlur-tor S6 and tho winding 17? of the reprinting roil S to tho point 190. 'llum'niuluro 196 of the polurizml ri-ln Vruspmnl; to until impulse ltllll (1030b .1 l through the relays 187 and 188. The said circuit for the relay 188 extends from ground (ift through the contael of springslot), springsfLtLl and tilt) and the relay lots to battery it. 'lltc"*l'elay 1813,

upon energizing, closes a locl iiug circuit-13nitself through the springs 'ltlt' and 192 independent of its energizing circuit. A further result of the cnergization of said relay is to close a bridge across the conductors St and so. thus energizing the line relay 107 (Fig. T of the connector ll. The said oncrgizing circuit extends from ground (1 through the lower winding of the line relay 1U? conductor 61. winding 18- of the repeating coil S". springs 193i springs 194, winding 183 of the repeating coil S, conduetor S0 and the upper winding of the line relay 107 to the battery lead 300. The said relay. upon energizing, closes an. energizing circuit through the relay 195 from'grouiul i through the contact of springs 196 and 197 and the relay 195 to the battery lead 300. The apparatus is now in readiness for the operation of the dial at; the operator's calling device for the first digit 2.

The operation at the said calling device for the first. digit 2 closes and opens the aforesaid circuit through the windings 175 and 176 of the repeating coil S thus trans mittin two impulses of current through the said windings. The said impulses of current induce corresponding im 'iulses of current in the windings 178 and 177 of the repeating coil S The armature 186 of the polarized relay, 185 responding to said 1nduced impulses operates to repeat the impulses to the relay 187 over a circuit extending from ground G through the contact of springs 189 and the relay 187 to battery B. The relay 187 responding to said impulses repeats the same to the line relay 107 of the connector H. Since the relay 195 is slow acting it does not dei nergize during the 1nomentary interruptions of its circuit by the relay' 107, so that each time the latter relay is deiinergized a circuit. iscloscd exteinling from ground G through the contact of springs 196 and 198, springs 201 and 199, relay 202. vertical magnet 97 and the side switch wiper .101 (in first-position) to the battery lead 300-. The vertical magnet 97 receives two impulses over this circuit and operates to raise the switch wipers 94. 95 and 96 to a position opposite the second level of bank contacts. The relay 202. which was included in Series with the \vertical magnet. remains in its energized position during the. entire time that impulses are being sent through it and operates to close the circuit of the private.magnet 105. After the last impulse is delivered. the relay 202 opens the. i

circuit of the private magnet 105, which. upon deenergiaing, permits the side switch to advance from first to second position. The movement of the side switch wiper 101 tors shown to'the called substation.

from first to second position transfers the battery connection from the vertical magnet, J7 to the rotary magnet 98. The operator now operates her calling device for the last digit 0. in response to which the connector line relay operates to transmit ten impulses through the rotary magnet 98 in series with the relay 202. whereby the shaft Wipers are rotated onto the contacts of the desired line. H the called line is idle. the private magnet 10;) dei nergizes when its circuit is broken by the relay 202 after the last impulse is deliverod. to the rotary magnet. The denergization of the said private magnet 105 allows the side switch to advance one more positionthat is, from second to third position. By the engagement of the wipers It)? and 104 with their third-position contact points and by the energization of the ln'idge-cut-otl winding 203 of the line switch (T. the eonnection is completed over the heavy ('oinlll(.-- The circuit for. the bridge-cut-ofi' windin'g 203 of the line switch C extends from ground (1 through the side switch wiper 102 (in third position), private wiper 95, conductor 204 and the winding 203to the battery lead 30 A guiu'ding ground potential is supplied to the connector private bank contactof the called line, which prevents the called line from being seizedby some other connector switch. By the engagement of the side switch wiper 191 with its third-position contaet point. the circuit of the ringing relay 109 is closed. This circuit extends from ground G through the interrupter 205i relav 1H9, springs 206 and the side switch wiper 101 (in third position) to the battery lead 300. Theringing relay; upon energizing. disconnects the calling line from the called line and bridges the ringing current generator h across the called line to signal the called subscriber. The ringing relay 109 is energized only intermittently through the medium of the interrupter 5205. Upon the response of the called subscriber his line is provided with talking current; through the windings of the larch-bridge relay 108,Wh.ich

'rclay upon energizing. closes the circuit of the ringing eat-off relay 207. The said circuit extends from ground G through the side switch wiper 102 (in .third position), springs 208 of the relay 108 and the ringer cut-off relay 207 to the battery lead 300. The relay 20? upon energizing, interrupts the circuit of the ringing relay 109 at the springs 206 and closes a locking circuit for itself through its on n springs 209 independent of the springs 208 of the back-bridge relay N18. The operator 110W restores'the key It to normal, thus connecting the calling and called substations over the heavy conductors shown.

After the conversation is conuiileted, the connection is released uy the hanging up of the receiver at the calling substation in the following manner: When the receiver at the substation A is restored to the switchhoolc, the separation of the luck-switch spring destroys the energizing circuit of the relay 17 of the group of relays M. The

r lay 47, upon dciinergizmg, opens the hold mg circuits for the relay 122 of the selector E, the holding winding 0 and the relays 61 and 62 of the group of relays M. The deiinergization of the relay 1.22 of the selector E closes the circuit of the release magnet 31 of said selector. The said circuit extends from ground G through lhc contact of springs 119 and 118, springs 121, springs 116 and 117, ofl-noriml springs 32 and the release magnet 31 to the battery lead 100. The magnet 31, upon deenergizing, restores the switch shaft to normal position and its own circuit is broken at the oft-normal. springs 32 when the shaft reaches its lowest position. The winding 13 of the line switch (1. upon becoming deiinergized, allows the plunger arm 10 to return to normal position. The relay 61 dei nr-rgizing quicker than the relay 62 operates t trans mit an impulse of current through l' -e Wifltlings 45 and 44- of the repeating coil 55. The said impulse of current extends from the positive pole of the high voltage battery B through. the contact of springs 110, springs 139. winding 45 of the repeating coil S, lower winding of the relay 47. the positive pole of battery B, through battery B, h per Winding of the relay l7, Winding 41 o the repeating coil fisprings 138 and the springs 141 to the opposite pole of battery 15. As shown in the drawings the relay ll-is a p larized relay, and although current at this time passes through the winding of said. relay its armature will not be attracted as the current in the above traced circuit from the hi gh voltage battery B is flowing in the opposite direction from that which is re quired for the o era tion of this relay. The said impulse o'l current induces a corresponding impulse of current in the windings 46 and 47 of the repeatin Y coil S extending from the point 68 throng 1 the winding 47 of the repeating coil S, conductor 39, Winding 50 of the repeating coil S liola-riaerlv relay 49, winding 51 of the repeating coil S, conductor 4.0 and the winding 46 of the repeating coil to the point 68. The armature 55 of the polarized relay responding to said impulse opens the holding circuit of the relay 57 at the springs 216. The relay 57, upon delinerg'izing, opens the bridge across the conductors 59 and 60. thus allowing the line relay 165 of the cord circuit 0 to dciinergize. The relay 165, upon deem ergizing, closes a circuit through the supervisory lamp 82, thus signaling the operator that the connection has been terminated. The operator removing the plug p from 13 of the line switch 1hr jack j destroys the energizing circuit of the relays 166 and 159. The relay 159, upon det'cncrgizing. opens the holding circuit of the relay 151 of the selector F at the springs 211, which allows the selector to return to normal position in a manner similar to that hcrcinbefore described for the selector E. The relay 166, upon dei nergizing, opens the circuit of the supervisory lamp 82 at the springs 167. The operator then removes the plug from the jack j, which destroys the holding circuit of the relays 171 and 172 of the group of relays Q, (Fig. 5). The said relays, upon dciinergizing, cause the relay 188 (Fig. 6) to open the energizing circuit of the line relay 107 of the connector H in the same manner that -the relay 57 (Fig. 3) opened the energizing circuit of the relay 165 of the cord circuit 0.

the circuit ol the relay 195, thus completin a circuit extending from ground G t n'oug the contact of springs 196 and 198, springs 201 and 212, off-normal springs .213 and [he release magnet 106 to the battery lead 300. The inagl'uel, upon energizing, restores the switch shaft and side switch wipers to normal position and its own circuit is broken at the springs 213 when the shaft reaches its lowest position.

It the number called is busy, there will he a guarding p tential upon the connector private bank contact, just as explained in connection with the line switch C. The connector private wiper 95. upon engaging this guarding contact, and before the side switch wipers have passed to third position. coinpletcs an energizing circuit through the busy relay 5314. This circuit extends from ground at the private wiper through the side svitrh wiper 102 (in second position), springs 217 and JUL relay 214-. springs 220 and 2151 and the priva c magnet 165 to the battery lead 2W0. The privale nuignct is thus hold encrgizwl and retains the side switch in second position. The relay :14. upon energizing. opens the circuit of lhe rotary magnet 98 at the springs 215. and also circuit for itself bringing th spring .218 into contact with the spring 316, thereby disconnecting the spring 2 16 from the spring 217. The en gagenient of the springs a-circuit for the busy tone extending from the busy machine L through the said springs 2'19, side switch Wiper 104 (in second position), condenser 292. over the heavy conductor. through the calling telephone and over the return conductor to the busy machine l). The calling subscriber. upon receiving the busy signal, replaces his receiver upon the receiver hook, thereby releasing the connection in the manner above described.

it having been explained how a connection is completed from the subscriber A to The relay 107. u ion deiinergizin 0 mos 21,9 serves in close I the subscriber A by moans of physical circuit trunk linos. it will now bo explained how the anbncribor may call the suhscribor A ovcr phantom oirouit trunk lines. We will assume that tho milling subscriber must; call the number 32 to obtain connection with the oporatru' at tho inlorniodiato exchango ()\(l' a phantom circuit. trunk lino. Sineo the opt-rations of tho lino switch U and tho acleotor ll havo heroiuliotoro boon dosouboil. no will assumo that tho auhaorihor A has romovorl his roooiror and rotated his dial for tho liral digit 3 Hninorliug tho. wipols 1Z5, Qfifillltl :3? of tho iii-at Hiltt'lUI' E with tho hank mutants 22th .2124- aud As soon as tho oounortir'in is romplctorl to the conductors 2'16, 22? and 228. tho lino relay 7-1 oil. the rupoater I (Fig. 4) is energized, said oirouit oxtonding from gromul ti through tho lowor winding of tho rolay 7r conduntor 228, through tho nubstation A, over the return conductor 2% and through tho nppor winding ol' the rolay H to the huh tory lead 100, lh rolay Tl. upon (um-giviin;g olosos a rirruit through tho rolajr 7:") and hrulggos tho hnpodanro coil 223 :u'roas tho trunk conihiolori: tit -l0 and 3 til. 'llio ouorgrizing rirouii for tho rolay 7h ox tonds from ground (i through the ront'aot of springs 230 and 2'29 and tho relay T5 to tho battery load 100. The rolay 75. upon onorgizing. oomplotoa holding oircuit for the rola 12" of tho z-+oloolor E and the hold in;: winding 13 of tho lino switch ("1 The said holding: (ll'titlt for tho rola} l2) oxttlltlH From ground (1 through tho mutant, of springs 23), oorulnolor 252T. uipor L 6 springs 13'") and 132 and tho rolay ['32 to tho hattory load lll l Tho holding rirruilfor tho uiniling Ill ol th" lino swiu-h oxtonlls oror tho almrolraood c irruit to tho o. ipor 26 Mom hor iho ('iHlill oxtoudn through tho ooulaot ot' sprin -w 21i; -pring lliw and lf'iih hank apring and. W and through tho winding t2) to tho lmllorr load l ll'i. 'llio lol'lniual ((illlllll'llil'h 1'; and Q7 of tho phaw tom rircuit trunk may torminato in a solw tor switvh in tho intornwdiato ouchaugo (not shown) aimilar to tho s lot'tor F.

\Vhon tho calling; dc\ h'o at tho aul-ataiion" is oporatoil. tho waparalion of tho ilupnlxo springs 7 and H allows lho lino rolar Tl o'l tho ropoator l to doonorgixo. llarh limo tho rolar Tl iloi uorn'izos. tho wpriuoj 121m nuuuru larily disonggagm tho spring! 22 and ongmgoa tho spring 2 3i and tho aprin g 2 1 dison gag-m tho RPllltLl' 217-5. The oporati n f tho Hprinoa .lf l and 235 opons tho hridoo arrow th oondin-tom tit" and 63. than roru-atiu; tho ihipnlaos from tho auhstatimi to tho so lortor switch at. tho intormodiato oxohange. Sinoo tho rolay 7.) is slow noting it does not, loi norn-irw during tho momontary soparation of tho springs: .229 and 230. (onscqucntly the cngagen'iontof tho springs .230

and 231 (loses a rircuit. through the relay Tt. This circuit oxtouds from ground G through the rontart of springs 230 and 231, springs 236 and tho rolay 76 to the battery lead 100. "lho rolay 76 is energized bytlie first, impulst and, being slow acting, remains in its operated position until all'the impulses for the digit. are. delivorod. In it'ts onorgizoll position the relay 76 operates to dmconnort tho oonduotors 64* and 65 from tho roiuilonsors 'TT and 78 and to ahnrt-cirouit; the impodanoc coil. 233 to prevent its iutcrt'oronoo with tho operation of the switches at tllo distant exchange.

Whon the substation calling dorice is operated for the second digit 2, tho ropoator oporatcs in the manner oxplainod to repeat two irnpulhos ovor tho trunlc conductors- 39---4O and (5341l to a selector in the intornu-diato uxchango. This Helootoi' oporatos in tho same uiannor as tho solootor F to' oxtond tho connection to a group of relays similar to tho group of relays K. Tho opt'rtor amwors by moans of at 00rd oircuit 0 similar to tho cord circuit 0, ox'copt that tho proliinluary llllPlllSP rolay 835 is tlispclhml with. 'Ihc oporator, upon rocoiviug the railing: snhscribofs ordor, insor-tS tho plug p into a jack ronnootcd to the phantom tap conductors and 91 of tho trunk lines 86--8T and Si --89, which extends the connection to the third oxchaugo. The plan tom tap Conductorn 9:? and 93 (Fig. (3) or the mid trunk linos 8(3S7 and SH-- Sl torniinato in a counoctor Hwitoh (not shown) in the third oxrhang'o similar in all rcsports' to tho connootor switch ll. Tho operator thou liridg'os hor (-allintr \lovioo (tho impulse nprings lloinu' normally rlowil) across tho phantom tap conductors 9() and 1 and opou atos tho dial in :n-rordanoo with tho dosirod numbor to comploto the uonnootion to tho oallod suhsrribcr, as horoinho'l'oro dost'rihodi 'lho roloa o of tho apparatus is priu'tioally tho mun as ln-roinlwl'oro iuonlionoil and is llilllilll'tl h tho walling uuhaoribor X roplarin hi rovoivor upon tho toroiror hook.

It will thus ho soon that, I havo devised a 'ory ollirirnl form of automatio tolcphonc s wtom in which a phantom circuit can he ai wri|npimod on trunk linon over which an aulou|atironuooti'on is vatahlishod. this beng brought about in such a mannor that noithor ouo ot' tlioso rounootions intorforos in "any way with tho othor. Flutluumorr.

it will ho soon. that tho oonuootiou can ho ,of 'said subscribers lines, and a phantom signaling circuit superimposed on said trunk lines.

2. In a telephone system, ,a plurality of subscribers lines, means including a trunk line and automatic switches controlled over said trunk line for extending a connection between two of said lines, a second trunk line and automatic switches controlled thereover for establishing a second connection between two of said lines, and a phantom signaling circuit superimposed on said trunk lines.

3. In a telephone system, a plurality of subscribers lines, means including a trunk line and automatic switches for extending a connection between two of said lines, means including a second trunk line for extending a second connection between two of said subscribers lines, a phantom circuit superimposed on said trunk lines, and means includin automatic switches for establishing a ta king circuit including said phantom circuit.

4. In a telephone system,a plurality of subscribers lines, means including a trunk line and automatic switches controlled over said trunk line for extending a connection between two of said lines, a second trunk line and automatic switches controlled thereover for establishing a second connection between two of said lines, a phantom circuit superimposed on said trunk lines, and means includin automatic switches for establishing a ta king circuit including said circuits, and a phantom signaling circuit superimposed on said physical circuits.

6. In a telephone system, a pair of physical'trunk circuits, means for controlling antomatic switches over either of said physical circuits, and a phantom signaling circuit superimposed on a portion of said physical circuits, said portion of the physical circuits being conductively insulated from the remainmg portion of said circuits.

7. In a telephone system, a pair of physical trunk circuits, means for controlling antomatic switches over either of said physical circuits, a phantom circuit superimposed onsaid physical circuits, and means for controlling automatic switches over said phantom circuit to establish a talking circuit.

8. In a telephone system, a pair of physical trunk circuits, means for controlling automatic switches over cithc'r of said physical circuits, a phantom circuit superimposed terminating in the primary winding of an.

induction coil, a second trunk terminating in the secondary of said induction coil, a re lay at the opposite end of said second trunk, and means for automatically transmitting an impulse through the primary of said induction coil when connection is made with said first trunk to thereby induce an impulse of current by clectrrmiagnetic inducl ion in said second trunk to thereby operate said relay.

11. In a telephoncsystcm. a trunk line terminating in the primary winding of an induction coil, a second trunk terminating in the secondary of said induction coil, a relay at the opposite end of said second trunk, means for automatically transmitting an impulse though the primary of said induction coil when connection is made with said first trunk to thereby induce an impulse of current in said second trunk to thereby opcrate said rclay, a third normally inoperative trunk inductively associated with said second trunk, and meanscontrolled by the initial operation of said relay for renderin said third trunk operative.

I2. In a telephone system, a trunk line, a relay in said trunk, means imluetivoly rclatcd to said trunk for trmismitting a series of induced impulses over said trunk to operate said relay, and 'an automatic switch controlled by said relay.

13. In a telephone system, a plurality of subscribers lines, mcaus'for establishing a connection between two of said lines. said means including a trunk line ronduciively insulated from the remainder of said con nection, and automatic switches for use in establishing said connection controlled by induced impulses transmitted over said con ductively insulated portion of said lrunk line by electromagnetic induction.

14- In a telephone system, a plurality of subscriberslines, a trunk line, a second trunk inductively related to said first trunk, a relay in said second trunk, means for extending a connection from a calling line to said first trunk, means for transmit in? a, p urality of series of impulses to said rst ffinlg; means for thereby inducing a corresponding series of impulses in said second trunk and through said relay by electromagnetic induction, and means including an automatic switch controlled by said relay for completin the connection to it called line.

15. n a telephone system, a polarized relay, an automatic switch, and means for operating said relay by induced impulses of one direction to operate said switch and by induced impulses of the opposite direction to control the release of said switch.

16. In a telephone system, a trunk line, a polarized relay n said trunk, means lnducs li\ely related o said trunk to transmit a series of induced impulses over said trunk in one dirc tion to operate said relay, an an t mati switch controlled by said operation f said relay, means for transmitting an induced impulse over said trunk in the oppo site direction to again operate said relay, and means controlled by the latter operation of said relay to release said automatic switch.

17. In a telephone system, a plurality of subscribers lines, means for establishing a connection between two of said lines, said means including a trunk line conductively insulated from the remainder of said. conmotion, and automatic switches for use in establishing said connection controlled by induced impulses transmitted in one direc tion over said conductively insulated portion of said trunk line. and released by an induced impulse transmitted in the opposite direction over said portion of said trunk line.

18. In a telephone syslem, a plurality of subscribers lines, a trunk line. a second trunk inductively related to said first trunk, a polarized relay in said second trunk, means for extending a connection from a falling line. to said lirsl trunk, means for transn'iitting a plurality of series of impulses in one diil'ection over said first trunk, means For therdliy inducing the corrcspondiin, rics of impulses in said second trunk through said relay, an automatic switch controlled by said operation of said relay, means for transmitting an inductive impuls" if the opposite direction through said relay, means controlled by this last operation of the relay .to control the release of said switch, and means controlled by said switch for completing the connection to a aillcd line.

19. In a telephone system, trunk line, a normally inoperative trunk extending therefrom, meanstl'or establishing connection with said first trunk, means controlled by the establ'islnncnt of said connection for rendering said second trunk operative, a third trunk line, and a phantom signaling circuit superimposed on said first and third trunk lines.

20. In a telephone system, a trunk line, a imrtnally inoperative trunk extending therefrom, means for establishing connection with said first trunk, n'icans controlled by the establishment of said connection for transn'iitting a preliminary impulse over.

said first trunk to render said second trunk operative, a third trunk line, and a phantom signaling circuit superimposed on said first and third trunk lines.

21. In a telephone system, a trunk line, a second normally open trunk inductively associated with said first trunk, means for establishing a. connection with said first trunk, means controlled by the establishment of said connection for closing said second trunk, a third trunk line, and a phantom signailing, ircuit. superimposed on said lirst and third trunk lines.

2. in a telephone system, a trunk line terminating in the primary winding. of an induction coil, a second trunk terminating in the secondary of said induction coil, a relay at the opposite end of said second trunk, means for autolnatically transmitting an impulse through the primary of said induction coil when connection is made with said first trunk to thereby induce an impulse of current in said second trunk to thereby ope ate said relay, a third trunk line, and a phantom signaling circuit supcrinniosed on said sec ond and third trunk lines.

255. In a telephone system, a trunk line terminating in the primary winding" of an induction coil, :1 second trunk terminating in the secondary of said induction coil, a relay at the opposite end of said second trunk, tin-ans for automatically transmitting an impulse through the primary of said induction coil when connection is made with said lirst. trunk to thereby induce an impulse of current in said second trunk to thereby operate said relay, a third normally inoperative trunk'inductively associated with said second trunk. means controlled by the initial operation of said relay for rendering said third trunk operative, a fourth trunk line, and a phantom signaling circuit superimposed on said second and fourth trunk lilies.

24. In a telephone system. a trunk line, a relay in said trunk, meansinductively rclatcd tosuid trunk for transmitting a series of induced impulses over said trunk to operate said relay, an automatic switch controlled by said relay, a second trunk line, and a phantom signaling circuit superimposed on said trunk lines.

25. In a telephone system, a plurality of subscribers lines, means for establishing a connection between two of said lines, said means including a trunk line conductively insulated from the remainder of said connection, automatic switches for use in establishing said connection controlled by induced impulses transmitted over said conductively insulated portion of said trunk line, a second trunk line, and a phantom sigi aling circuit superimposed on said trunk mes.

26. In a telephone system, a plurality of subscribers lines, a trunk line, a second trunk inductively related to said first trunk, a relay in said second trunk, means for extending a connection from a calling line to said first trunk, means for transmittin a plurality of series of impulses to said rst trunk, means for thereby inducing a corresponding series of impulses in said second trunk and through said relay, means in cludin an automatic switch controlled by said re ay forcompletin the connection to a called line, a third trun line, and a pliantom signaling circuit superimposed on said second and third trunk lines.

27. In a telephone system, a trunk line, a polarized relay in said trunk, means inductively related to said trunk to transmit a series of induced impulses over said trunk in one direction to operate said relay, an automatic switch controlled by said operation of said relay, means for transmitting an induced impulse over said trunk in the opposite direction to again operate said relay, means controlled by the latter operation of said relay to release said automatic switch, a second trunk line, and a phantom signaling circui-t superimposed on said trunk line.

28. In a telephone system, a plurality of subscribers lines, means for establishing a connection between two of said lines, said means including a trunk line conductively insulated from the remainder of said connection, automatic switches for use in as tablishing said connection controlled by induced impulses transmitted in one direction over said conductively insulated portion of said trunk line and released by an induced impulse transmitted in the opposite direction over said portion of said trunk line, a second trunk line, and a phantom signaling circuit superimposed on said trunk lines.

29. In a telephone system, a plurality of subscriberslines, a trunk line, a second trunk inductively related to said first trunk, a polarized relay in said second trunk, means for extending a connection from a calling line to said first trunlqmeans for transmitting a plurality of series of impulses in one direction over said first trunk, means for thereby inducing the corresponding. series of impulses in said second trunk 'through said relay, an automatic switch controlled by said operation of said relay, means for transmitting an inductive impulse of the opposite direction through said relay, means controlled by this last operation of the relay to control the release of said switch, means controlled by said switch for completing the connection to it called line, a third trunk line, and a phantom signaling circuit superimposed on said first and third trunk lines.

30. In a telephone system, a plurality of subscribers lines, means for establishing a connection between a pair of said lines, means for establishing a second connection between another pair of said lines, both of said means including a trunk line, together with a normally inoperative trunk extending therefrom, means for establishing connection with either of said first trunks, means controlled by the establishment of said connections for rcndering the corresplonding second trunk operative, and a p antom signaling circuit superimposed on said first trunks.

31. In a telephone system, a plurality of subscribers lines, means for establishing connection between a pair of said lines, means for establishing a second connection between another pair of said lines, both of said means including a trunk line, together with a normally inoperative trunk extending therefrom, means for establishing connection with either of said first trunks, means controlled by the establishment of said connections for transmitting a. preliminary impulse over the corresponding first trunk to render the corresponding second trunk operative, and a phantom signaling circuit superimposed on said first trunks.

32. In a telephone system, a plurality of subscribers lines, means for establishing a connection between a pair of said lines, means for establishing a second connection between another pair of said lines, both of said means including a trunk line, a second normally open trunk inductively associated with each of said first trunks, means for establishing a connection with either of said first trunks, means controlled by the establishment of said connections for closing the corresponding second trunk, and a phantom signaling circuit superimposed on said first trunks.

33. In a telephone system, a pair of trunk lines, a relay in each of said trunks, means inductively related to each of said trunks for transmitting a series of induced imfor establishing a second connection between two other of said lines, each of said means including a trunk line conductively insuluted from the rcn'iainder of the corresponding connection, automatic switches for use in establishing said connections controlled by induced impulses transmitted at the conductively insulated portion of the corresponding trunk line, and a phantom signaling circuit superimposed on the conductively insulated portions of said two trunks.

35. In a telephone system, a plurality of subscribers lines, means for establishing a connection between two of said lines, means for establishing a second connection between two other of said lines, each of said means including a trunk line conductively insulated from the remainder of the corresponding connection, automatic switches for use in establishing said connections controlled by induced impulses transmitted at the conductively insulated portion of the corresponding trunk line, a. phantom signaling circuit superimposed on the comluctively insulated portions of, said two trunks, and means for controlling automatic switches to establish a third talking circuit over said phantom circuit.

343. In a telephone system, a plurality of subscribers lines, means for establishing a connection between two of said lines, means for establishing a second connection between two other of said lines, each of said means including a trunk line comluctivcly insulated from the renniinder ot' the corresponding connection, automatic switches for use in establishing said connections operated by induced impulses transmitted in one direction over said conductivcly insulated portion of the correspomling trunk line and released by induced impulses transmitted in the opposite direction, and a phantom signaling circuit superimposed on said conductircly insulated portions of said two trunks.

iii. In a telephone system, a plurality of subscribers lines, means for establishing a connection between two of said lines, mean for establishing a secondconnection between two other of said lines, each of said means including a trunk line conductively insulated from the remainder of the correspond ing connection, automatic switches for use in establishing said connections operated by induced impulses transmitted in one direction over said eondllrtivcly insulated portion of the mirrespomlingtrunk line and released by induced impulscstransmitted in the op posite dircct ion, a phantom signaling circuit. superimposed on said conductivcly insulated portions ol said two trunks, and means for controlling automatic switches to establish a third talking), circuit over said phantom circuit.

3H. lo a telephone system. a trunk line, means l'or cxlending a connection to said trunk, a generator at one end of said trunk, a polarized relay at the opposite end of said trun k, a normally open circuit for extending a connection from said trunk, means for musing the generator to produce a preliminary impulse to operate said polarized relay to close said normally open trunk when connection is established with said first trunk, means for subsequently controlling the generator to send a series of. impulses through said relay, and an automatic switch connected to the opposite end of said second trunk controlled by said relay.

3!). In a telephone system, a calling and it called subscribens line. means for extending a connection between said lines, said means including a physical phantom circuit, automatic switches for extending a connection from a calling, line to said circuit, an open ators board, means for extending a connee tion from said physical phantom circuit to said opcrators board, a second physical phantom circuit, means for extending a connection from said operatoNs board to said second physical phantom circuit, and automatic switches for extending a connection from said second physical phantom circuit to the called line.

4H. In a telephone system, a section of a talking circuit, a bridge across said section, a second talking circuit passing through a point in said bridge. a second bridge acro s said section, said second talking circuit passing also through a point in said second bridge, and an automatic progressively mo able switch associated with said second bridge and controllable thereby.

41. In a telephone system, a section of a talking circuit, a bridge across said section, a second talking, circuit passing through a point. in said bridge, a second bridge across said section, said second talking circuit pass-- ing also through a point in said second bridge, an inductive windingin said first bridge, a relay in said second bridge, and an automatic switch controllable through the medium of said relay.

4-2. In a telephone system, a section of a talking circuit, a bridge across said section, a second talking circuit passing through a point in said bridge, a second. bridge across said section, said second talking circuit passing also through a point, in said second bridge. an inductive winding in said first. bridge. a relay in said se ond bridge, and an automatic progressively movable switch associated with said second bridge and controllable thereby.

l3. lo a telephone system, a section of a talking circuit, a bridge across said section, a second talking circuit passing through a point in said bridge, a second bridge across said section, said second talking circuit pass ing also through a point in said second bridge, an inductive winding in said first bridge, a relay in said second bridge, and an automatic progressively movable switch associated with said second bridge and controllnble through the medium ot said relay.

44. In a telephone system, a pair of con ductors for talking purposes, a pair of bridges across said conr uctors, a second talking circuit passing through a point in each of said bridges, and an automatic switch associated with one of said bridges and controllable thereby.

45. In a telephone system, a pair of conductors for talking purposes, a pair of bridges across said conductors, a second talking circuit passing through a point in each of said bridges, an inductive winding in one of said bridges and a relay in the other, and an automatic switch controllable through the medium of said relay.

46. In a telephone system, a pair of condoctors for talking purposes, a pair of bridges across said conductors, a second talking circuit passing through a point in each of said bridges, an inductive winding in one of said bridges and a relay in the other, a line, means for extending the two sides of said line into inductive relation with said Winding, and means controlled over said line for inducing current in said winding to operate said relay.

47. In a telephone system, a pair of conductors for talking purposes, a pair of bridges across said conductors, -a second talking circuit passing through a point in each of said bridges, an inductive winding in one of said bridges and a relay in. the other, a line, means for extending the two sides of said line into inductive relation with said winding, means controlled over said line for inducting current in said winding to operate said relay, and an automatic switch controllable through the medium of said relay.

48. In a telephone system, a pair of condudtors for talking purposes, a pair of bridges across said conductors, a second talking circuit passing through apoint in each of, said bridges, an inductive Winding in one of said bridges and a relay in the other, a line, means for extending the two sides of said line into inductive relation with said winding, means controlled over said line for inducing current in said winding to operate said relay, other lines, and an automatic switch controllable through the medium of said relay to extend connection to one of said other lines.

49. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a pair of bridges for each of said sections, a third talking circuit passing through a point in each of said bridges, an automatic switch associated with a bridge at each of said sections and controllable tgereby, i, a 1

including a relay,

50. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a pair of bridges for each of said sections, one bridge in each of said pairs including a relay, a third talking circuit passing through a point in each of said bridges, and an automatic switch controlled by each of said relays.

51. In a telephone system, a section-of a talking circuit, a section of a second talking circuit, a pair of bridges for each of said sections, one bridge in each of said pairs including a relay, the other bridge in each of said pairs comprising an inductive winding, a third talking circuit assing through a point in each of said bri ges, and an automatic switch controlled by each of said relays.

52. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a pair of bridges for each of said sections, one bridge in each of said pairs including a relay, the other bridge in each of said pairs comprising an inductive winding, a third talking circuit passing through a point in each of said bridges, an automatic switch controlled by each of said relays, and means for inducing currents in one of said, windings to operate the associated relay for controlling its associated automatic switch.

53. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a pair of bridges for each of said sectiom, a third talking circuit passing through a point in each of said bridges, an automatic switch associated with a bridge at each of said sections and controllable thereby, other automatic switches, and means for controlling one or more of said other switches over said third talking circult.

54. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a pair of bridges foreach of said sections, one bridge in each of said pairs including a rela a third talking circuit passing through a point in each of said bridges, an automatic switch controlled by each of said relays, other automatic switches, and means for controlling one or more of sald other sw itches over said third talking circuit.

55. In a telephone system, a section ,of a talking circuit, a section of a second talkin circuit, a pair of bridges for each of sai sections, one bridge in eachof "said,pairs the other, bridge in each of said pairs comprising an inductive winding, a t ird talking circuit passing through a point in each of said bridges, an automatic switch controlled by each of said relays, other automatic swltehes, and means for controlling one or more of saidpther switches over said third talking circuit.

56. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a pair of bridges for each ol said sections, one bridge in each of said pairs including a relay, the other bridge in each of said pairs con'iprising an inductive winding, a third talking circuit passing through a point in each of said l'n'idgcs, an antoniatie switch controlled by each oi said relays, means for inducing currents in one of said windings to operate the associated relay for controlling its associated automatic. switch, other auton'iatie switches, and means for controlling one or more of said other switches over said third talking circuit.

57. In a telephone system, a pair of conductors for talking purposes, a second pair of conductors for talking purposes, a pair of bridges for each of said conductor pairs, a circuit passing through a point in each of said bridges and an automatic switch controllable over said circuit.

58. In a telephone system, a pair of conductors for talking purposes, a Second pair of conductors for talking purposes, a pair of bridges for each of said conductor pairs. a circuit passing through a point in each of said bridges, a snbscriher s line, no antomat ie switch, means for extending said line by way of said circuit into connection with said switch, another subscribers line accessible to said switch, and means for controlling said switch. over said circuit to connect the. two subscribers lilies.

59. In a telephone system, a pair of conductors for talking purposes, a second pair of conductors for talking purposes, a pair of bridges for each of said coinluctorpairs, automatic progressively movable means for establishing a pair of talking connections each of which connections includes one of said conductor pairs, a circuit mssing through a point in each o'l said bridges, and an automatic switch controllable over said circuit.

60. In a telephone system, a section of a talking circuit, a winding included in said section, a second talking circuit including said winding, a relay in said section. said second talking circuit including also the coils of said relay, and an automatic switch controlled by said relay.

($1. In a telephone system, a section of a talking circuit, a winding included in said section, a second talking circuit including said winding, a relay in said section, said second talking circuit including also the coils of said relay, an automatic switch controlled by said relay, and means for. inducing current impulses in said winding to operate said relay.

62. In a telephone system, a section of a talking circuit, a winding included in said section, a second talking circuit llit'llltlillfl, said. winding, a relay in said section, said second talking circuit including also the coils of said relay, an automatic switch controlled by said relay, a plurality of extensions for said section associated with said switch, and means for inducing current impulses in said winding to operate said relay, whereby said switch is controlled in extend the said section via one of said extensions.

ea. In a telephone system, a section of a talking circuit, a winding included in said section, a scconl talking circuit including said winding, a relay in said section, said second talking circuit including also the coils of said relay, an automatic switch controlled by said relay, a plurality of exten sions for said section associated with said switch, means for inducing current impulses in said winding to operate said relay, whereby said switch is controlled to extend the said section via one of said extensions, and means for inducing a different current inipulse in said winding to operate said relay in a dill'crent manner to release said switch.

ti l. In a telephone sy tem, a section of a talking circuit. a section of a second talking circuit, a winding and a relay in each of said sections, a third ircuit including all of said windings and all of said relays, and an auto nialic swilch associated with each of said relays and controllable thereby.

(35. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a winding and a relay in each of said sections, a third circuit including all of said windings and all of said relays. and an automatic switch. controlled over said third circuit.

86. In a telephone system, a. section of a talking circuit, a section of a second talking circuit, a winding and a relay in each of said sections, a third circuit including all of said windings and all of said relays, an automatic switch associated with each of said relays and controllable thereby, and an automatic switch controlled over said third circuit.

(37. In a telephone system, a section of a talking circuit, a section of a second talking circuit, a winding and a relay in each of said sections. a third circuit including all of said windings and all of said relays, an automatic switch associated with. each of said relays and controllable thereby, another .section for each of said first and sec ond talking circuits inductively related to the windings therein, and means for of feeling current changes in one of said last sections whereby one of said relays is open ated by currents induced in its associated winding.

68. In a telephone system, a section of a talking circuit, a section. of a second talking circuit, a winding and a relay in each of said sections, a third circuit including all of said windings and all of said relays, an

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