US1314711A - smith - Google Patents

Description

AFB. SMITH.

uromflc msruous svsnm. APPLICATION FILED MAR. 25- I916.

Patented Sept. 2, 1919.

Hlfarnsy A. B. SMITH.

AUTOMATIC TELEPHONE SYSTEM. 1 .Iwrucman nuznfun. 2:. ms. Patentedsept' 2 1919. l spins-sum Hflfar'ngy A. s. smm.

AUTOMATIC TELEPHONE SYSTEM.

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' A. B. SMITH.

AUTOMATIC IELEPHONE SYSIHL m'ucmou min HA8. 25. 1910.

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A. B. SMiTH.

AUTOMAUC TELEPHONE SYSTEM.

. APPLICATION FILED MAR. 25. HHS. 2,

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[must-liar M @LMQM H1701" may STATES PATENT OFFICE.

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

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Sept. 2, 1919.

To all whom it may concern:

Be it known that I, ARTHUR Bnssnr SMITH, a citizen of the United States of America, and a resident of Evanston, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates to automatic telephone systems and more particularly to such systems as comprise a plurality of exchanges interconnected by toll or long distance lines.

In systems of the above general character it has been found desirable to provide means whereby the operators in one exchange may establish connection with subscribers in a second exchange automatically and without the intervention of operators in the second exchange. It is also desirable, in the interest of economy, to superimpose phantom circuits on such toll lines in order to obtain additional circuits without additional outlay for physical conductors.

Considerable difliculty has been experienced in the past in providing operating circuits for the automatic switches where ph ntom circuits are superimposed on the toll lines, it being necessary in order to obtain quiet operation of the phantoms to maintain a balanced condition of the corresponding physical circuits.

It is the principal object of my invention to provide a new and more efficient system of automatic calling over lines having superimposed phantom circuits, whereby connections may be established automatically over the physical circuits without interference of any kind between the physical circuits themselves or between physical circuits and phantom circuits.

In carrying out my invention in connection with two toll lines having a superimposed phantom circuit, I employ preferably a so-called simplex circuit superimposed on the phantom circuit, which simplex circuit is utilized for operating a well known type of qu-adruplex apparatus, through the medium of which I am enabled to control two setsof automatic switc e at ea h an f the toll lines separately or simultaneously, as desired.

Further objects of my invention relate to details of circuit arrangement and devices whereby the previously mentioned quadruplex apparatus is modified to adapt it to control automatic switches of well. known type, and to various other circuit arrangements whereby toll lines equipped in accordance with my invention may be used for manual connections if desired without operating their associated automatic switches.

These and other objects will appear more clearly and will be described more fully hereinafter, reference being had to the accompanying drawings.

For a clear understanding of the drawings, Figures 1, 2, and 3 should be arranged in order with the lines at the sides thereof in alinement, Fig. 4 should be joined at its left hand end to the lower right hand corner of Fig. 3, and Fig. 5 should be placed as a continuation of Fig. 4. The apparatus shown in Figs. 1 and 2 is located in what I shall hereinafter designate as the No. 1 exchange, while the apparatus shown in Figs. 3, 4, and 5 is located in what I shall hereinafter designate as the No. 2 exchange.

When the drawings are properly laid out and joined together it will be seen that I have shown a toll line 101-102 extending from jack J 2 in the No. 1 exchange to jack J 5 in the No. 2 exchange; a second toll line extending from jack J 4 in the No. 1 exchange to jack J in the No. 2 exchange; and a phantom circuit superimposed in the regular manner upon the said toll lines and extending from jack J in the No. 1 exchange to jack J a in the No. 2 exchange.

It will be shown hereinafter that all three of the above lines are adapted for manual operation in both directions, while the physical lines are also adapted for auto 0 eration in both directions. In accomplis ing the latter operation I employ, as before stated, a so-called simplex circuit superimposed on the phantom circuit in an obvious manner and evidently terminating at the respective exchanges in certain apparatus in dicated by reference characters '1 and T (Figs. 2 and 3). The apparatus shown at I and T comprises a modified form of well known quadruplex equipment whose operation and particular function in connection with my invention will be fully described in the detailed specification.

To better facilitate the understanding of my invention 1 have elected to show a part of the ap 'iaratus in operated position whereby a complete circuit connection has been established between a calling substation A (Fig. 1) and a called substation A (F1 5). The said connection has been established through the medium of multiple jack J, cord circuit P, jack J, repeating coil R toll line 103-l04, repeatin coil R, selector switch E, selector switch and connector switch H.

The substation A (Fig. 1) may be of any suitable type or construction such, for example, as the type disclosed in British patent to T. G. Martin, No. 1419 of 1910. As shown herein it comprises essentially the receiver 2, transmitter 3, switch hook 4, ringer 5 and condenser 6. Being an automatic substation there is also provided a pair of impulse springs 7 and 8 controlled by the impulse wheel 9 throu h the medium of a fin er hole dial (not 5 own).

he line conductors 12 and 13 of the substation A are connected at the No. 1 exchange to the individual line switch 0 which may be of the general type of line switch disclosed in British patent to R. W. James, No. 26,301 of 1906; being, however, of the particular type shown in United States Letters Patent No. 1,078,690, granted Jan. 17, 1912,to Frank Newforth. Since line switches of the above type are well known and form no part of my invention an extended de scription will not be given. It will suflice to say here that through the medium of line switch G the line of substation A is given access to a plurality of selector switches (not shown) which may be similar to the selector switch E to be mentioned hereinafter. A three conductor trunk line which may be extended to one of these selector switches is indicated by reference characters 17, 18 and 19.

In addition to the line switch C there is also rovided for the line of substation A a multiple jack J which, as shown herein, is directly accessible to the toll o orator. It is to be understood, however, t at the toll operator ma complete connection locally by any other known method, the method hown having been chosen principally on account of its simplicity.

At P I have shown a toll operators cord circuit which may be of any suitable type althou h the particular type shown departs somew at from the usual design in order to provide for both manual and automatic operation. As shown herein, it comprises among other details a bridged relay 36 which, in conjunction with sleeve relay 35, controls the supervisory lamp L; and the ringing up locking relay 3'? which, in conjunction with sleeve relays 38 and 39, controls the supervisory lamp L. Keys K and K are ringing keys, key K is a listenin key, and key K is a calling device adaptedf when actuated, to include the calling device S in one strand of the cord circuit P.

The calling device S may be of any suitable type, it bein only required that the impulses produced in its operation shall consist of interruptions of the circuit in which it is included. Such a cal-ling device is shown in British patent to S. (1. S. Dicker, No. 29,654 of 1910. The callin device S may be common to a number 0% cord circuits or there may be, preferably, one such calling device for each toll operator.

The toll operator, besides having access to lines of the local sul'iscribers, has before her multiple jacks which are terminals of toll lines extending to other exchanges. The three jacks shown in Fig. 1., 2'. e., jacks J", c and J, are terminals of toll circuits extend ng to the No. 2 exchange, as has been previously mentioned. Considering the jack the tip and ring conductors extend by way of repeating coil R toll line 103-404, and repeating coil R to jack J (Fig. 3). It is evident that in a similar manner conductors extend from jack J (Fig. 1) by way of repeating coil R, toll line 101102, and repeating coil R to jack J 5 (Fig. 3). Superimposed on the two parallel toll lines may be seen a phantom circuit which extends from ack J (Fig. 1) by way of repeating 0011 R toll lines 101-102 and 103-404 in series, and repeating coil R to jack J 6 (Fig.

I In accordance with my invention the toll line 103104 is provided at the No. 1 exchange with a roup of relays M which relays are of uti ity in the automatic operation of the toll line and whose particular functions will be described in the detailed specification. At the No. 2 exchange a similar group of relays M is provided. Extendlng from relay group M is shown a two conductor trunk line 327328 which terminates in the selector switch E (Fig. 4). The trunk line 123-124 extending from relay group M is assumed to terminate in a selector switch similar to selector E but which is not shown.

It will be clear that toll line 101-102 is, like toll line 103104, provided with a group of relays in each exchange, which reay groups are indicated by reference characters M and M Also it will be seen that the relay groups M and M are provided with trunk lines 325-326 and 323- 324, which trunk lines are assumed to terminate in selector switches similar to selector E, one of these selectors being in fact shown at E (Fig. 1).

The selector switch E is of the general t pe of selector switch disclosed in United btates Letters Patent No. 815321, granted March 13, 1906, to Keith, Erickson, and Erickson; being, however, of the particular type disclosed in British patent to the Automatic Telephone Mfg. Co., No. 2543 of 1914. Such a selector switch, as is well known, may be operated in response to the first digit of a called number to select one of a number of main groups into which the lines of the No. 2 exchange are divided. For this purpose the selector E ma be given access to a number of groups 0 trunk lines one of which trunk lines is shown as extending to a second selector switch E, which may be similar to selector switch E in construction. The selector switch E responds to the second digit of a called number to select a subgroup in the main group with which it is associated, and to this end may be given access to groups of trunk lines extending to connector switches which in turn have access to the individual lines comprising the various sub-groups.

One of these latter trunk lines is shown as extending to the connector H, which may be of the general type of connector switch disclosed in United States Letters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson, and Erickson; being, however, more nearl of the particular type disclosed in Britisi patent to the Automatic Telephone Mfg. Co., No. 2270 of 1914. The connector switch H has access to a single group of subscribers lines and may be operated in response to the last two digits in a called number to complete connection to a wanted line in the group.

One line accessible to the connector H is shown in Fig. 5 as extending to the substation A, which may be similar to substation A (Fig. 1) already described. The line of substation A is provided at the No. 2 exchan e with an individual line switch C, which may be similar to the line switch C (Fig. 1). Conductors 431, 432 and 433 are assumed to extend t multiple jacks by which toll operators in the No. 2 exchange may be given access to the line of substation A.

Referring now to the uadruplex apparatus shown at T (Fig. 2 reference char acters 155 and 1556 indicate, respectively, the well known neutral and polar relays. As is well understood by those versed in the art, the neutral relay in a quadruplex system respends only to current of a certain strength independent of its direction, while the polar relay operates to close its contact in response to current in one direction and operates to open its contact in response to our rent in the opposite direction. The polar relay, moreover, does not depend for its op eration on a particular strength of current as does the neutral relay. The variable condenser 158 and the adjustable resistances 159 and 160 constitute an artificial line which is adjusted to balance the working line in well known manner. For supplying current to operate the neutral and polar relays I have shown four D. C. generators, 183, 184, 185, and 186. Generators 183 and 186 have their negative poles grounded, while generators 184 and 185 have their positive poles grounded. The enerators 183 and 184 are low voltage mac iines and deliver current which, while of sufiilcient strength to operate one of the polar relays, is not strong enough to operate a neutral relay. The generators 185 and 186 are of approximately three times the voltage of generators 183 and 184. Relays 157 and 154 are associated with the neutral relay and constitute what is commonly known as a bug trap. Relay 152 is the impulsing relay associated with the neutral side of the quadruplex system while relays 150 and 151 are the impulsing relays associated with the polar side. The apparatus shown at T (Fig. 3) is similar to the apparatus shown at T (Fig. 2) which has just been described.

It has been mentioned before that the toll lines in the system shown are adapted for manual operation as well as for automatic operation. There is shown, accordingly, a drop, cut-ofl relay, and busy lamp associated with each of the jacks J J J and J. In the case of jack J the above equipment is indicated by reference characters 109, 103, and L There is also shown in connection with the phantom circuit a drop 126 and cut-ofl relay 125 associated with jack J and a similar drop and cut-ofi' relay associated with jack J While I have shown throughout the drawings a plurality of batteries, it is to be understood that there is preferably but two of these batteries, one for each ex hange, and each having its positive pole grounded. Associated with the connector H I have shown a generator Gen for supplying ring ing current, an interrupter I for supplying intermittent ringing impulses, and a usy signaling machine N.

Having given a general description of the apparatus, I will now proceed to a more detailed explanation of the operation of the same. Inasmuch as a great deal of the automatic equipment shown here is well known and has been described fully in the publications previously referred to, the operation of such apparatus will be described in a more or less general manner. I will first describe the operations which take place when establishing the complete connection previously referred to between the substation A (Fig. 1) and the substation A (Fig. 5). The (all is assumed to have originated with the subscriber at substation A and the connection is therefore handled by an op erator in the No. 1 exchange.

Referring now to Fig. 1, the subscriber at substation. A, in initiating a long distance call, must first get into communication with a so-called recording operator at the No. 1 exchange. Any approved method of accomplishing this object will serve, but since the substation A is an automatic substation, it will be assumed that the operator has been called automatically as follows: Upon removing the receiver at substation A, the line switch C is operated to extend the line conductors 12 and 13 through to a selector switch, which may be the selector to which the trunk conductors 17, 18, and 19 extend. After the line switch has operated, the calling subscriber may inani 'iulate the finger hole dial of his instrument, thereby operating the selector switch to select a group of trunks extending to recording operators positions; after which the selector operates automatically to connect with an idle one of these trunks, all in a well known manner. The calling subscriber, upon hearing the operator respond, will give her the necessary information, such as the name and address of the person with whom conversation is desired, and also his own name and telephone number; and will then replace his receiver, thereby restoring his line switch and the selector switch to normal position. The recording operator in the meantime has written out the data received from the call' ing subscriber on a ticket, which is passed to a toll operator whose duty it is to complete the required connection.

In the case under consideration the wanted subscriber is located in the No. 2 exchange. The toll operator, therefore, observing first that the busy lamp L associated with toll line 103104 is not'lighted, inserts the calling plug of the cord circuit P in the jack J. By the insertion of the plug in the jack the following circuit is completed: ground at G winding of relay 38, winding of relay 39, sleeve of plug, sleeve of jack J and winding of cut-off relay 103 to battery B. Relay 38 is marginal and does not operate at this time. Relay 39, upon attracting its armature, closes a contact in the circuit of supervisory lamp L (of no consequence now, however). Relay 103, upon energizing, disconnects the tip and ring conductors of jack J from the drop 109 and connects them instead to windings of relay 100, and also closes a circuit extending from ground at (Si by way of contact springs 111 and 112 to busy lamp L and multiple busy lamps in other positions.

Since the connection is to be established automatically, the operator now throws her key K, thereby inserting the calling device S in one strand of cord circuit P, and at the same time, by closing contact springs 16 and 47, placing the resistance 40 in parallel with the relays 39 and 103. Relay 38 now receives sufficient current to enable it to operate and, upon so doing, it removes round from the armature of relay 39 and al so places a short around the condenser 48. The following circuit is thereby closed for relay 100: ground at G", Winding 101 of relay 100 contact springs 113 and 114, tip spring of jack J tip of plug, contact of key K, contact springs 45 and 44 of calling device S, contact springs 41 and 43 of key K contacts of relay 38, upper winding of relay 37, contact of key K, ring of plug, ring spring of jack J, contact springs 117 and 116, and winding 102 of relay 100 to battery B.

Relay 3? is operated upon the closure of the foregoing rircuit but without ell'ecl. at this time. Relay 100. however, upon attracting its armature. closes the following circuit: ground at G contact springs 119 and 120, winding of relay 152, and winding of relay 153 to battery B. Relays 152 and 153 are energized in series and, upon attracting their arinatures, complete the following o crating circuit extending to the distant o. 2 exchange: ground at G, D. C. generator 185, contact sprin s 181 and 180, con tact springs 173 and 1 4:, contact springs 170 and 171, wire junction 190, upper winding of neutral relay 155, left and right inner windings of polar relay 156, windings 212 and 213 of repeating coil R in parallel, windings 210, 211, 214, and 215 of repeating coils R and R in paralleL'line conductors 101, 102. 103, and 104 in parallel, windings 216, 217. 220, and 221 of repeating coils R and R in parallel, windings 218 and 219 of repeating coil R in parallel, left and right inner windings of polar relay 256, upper winding of-neutral relay 255, and contact sprin s 271 and 272 to ground at G. It will e seen that a branch of the above circuit extends from wire junction 190 by way of the lower winding of neutral relay 155, left and right outer windings of polar relay 156, and the artificial line to ground at G and G Currents in the above two branches through the windings of the neutral and polar relays 155 and 156 oppose each other and hence these relays are not operated.

At the No. 2- exchange the direction of current flow in the inner windings of polar rela 256 is such that this relay is operate to hold its armature against the back stop. The neutral relay 255 attracts its armature and closes a circuit for relay 257 as follows: ground at G, winding of relay 257, contact 256, and armature 263 to battery B. Upon energizing, relay 257 completes the following circuit for relay 254:: ground at G, contact springs 266 and 267, resistance 282, and winding of relay 25-1 to battery 13. Relay 25 1, upon energizing, closes a circuit for relays 128 and 129 over the following path: ground at U, contact springs 268 and 269, Winding of relay 129, and winding of relay 128 to battery B. Relay 129, upon energizing, closes the following circuit for relay 132: ground at G, contact springs 134 and 133, and winding of relay 132 to battery 15. Relay 132, upon attracting its armature, completes a circuit extending from ground at G by way of contact springs 139 and 140 to busy signal lamp L and its multiples, whereby the toll lino 103104 is made busy to operators in the No. 2 exchange. Relay 132 also disconnects the right hand windings of repeating coil it from the tip and ring conductors of jack J and connects them instead to trunk coiuluctors and 328 all in an obvious manner.

It will be remembered. that the energizing circuit of relay 129 also included the winding of relay 128. Upon energizing, relay 128 completes a circuit for the double wound line relay 350 of the selector E over the following path: ground at G, winding 357 of relay 350, back contact of relay 353, conductor 328, contact springs 137 and 138, winding of retardation coil 130, conductor 327, back contact of relay 353, and winding 358 of relay 350 to battery B Relay 350, upon energizing, completes a circuit for slow acting relay 351 which relay, upon energizing in turn, prepares circuits for the vertical and rotary magnets 355 and 356 in the well known manner.

The operator at the No. 1 exchange may now proceed to dial the wanted number. Upon the operation of the calling device S in accordance with the first digit, the impulse springs 41 and 45 are separated momentarily a number of times, interrupting each time the circuit of relay 100. As a result of these interruptions of its circuit, relay 100 denergizes a corresponding number of times and at each dee'nergization breaks the circuit of relays 152 and 153. The latter relay, being slow acting, does not deenergize when its circuit is opened momentarily. Relay 152, however, responds to the interruptions of its circuit and at each denergization substitutes the generator 181 for the generator 185 in the operating circuit extending to the No. 2 exchange. Since the voltage of generator 184 is but one third the voltage of generator 185, as previously mentioned, it will be readily understood that at each deenergization of relay 1.52 the current flow in the neutral relay 255 (Fig. 3) is reduced sufliciently to cause this relay to retract its armature. It follows, then, that the neutral relay 255 will vibrate its armature in accordance with the interruptions produced by the calling device S.

At each retraction of armature 263, the circuit of relay 257 is broken and a short is placed around relay 254. Relay 257, being slow acting, retains its armature during momentary interruptions of its circuit. Relay 254, each time its winding is short-circuited, retracts its armature, thereby interrupting the circuit of relays 129 and 128. Relay 129 is slow acting and accordingly does not respond. Relay 128, however, at each interruption of its circuit, deenergizes and in turn interrupts the circuit of the line relay 350 of the selector E.

It will be seen from the foregoing that the interruptions produced by the calling device S in the circuit of relay 100 are repeated in the manner described until they effect the circuit of the line relay 350. In response to these interruptions of its circuit, the line relay 350 is denergized a corresponding number of times and sends at each denergization an impulse from ground at G to the slow acting relay 352 and the vertical magnet 355 in series. The vertical magnet, in response to these impulses, steps up the shaft until the wipers stand opposite the horizontal level which contains terminals of trunk lines extending to the desired main group. The relay 352, being slow acting, retains its armature during the series of impulses and closes a circuit for the test relay 354, which latter relay, upon attracting its armature, locks itself to ground at Gr and also prepares a circuit for the rotary magnet 356. At the end of the series of impulses the relay 352 deenergizes, thereby closing the aforementioned rotary magnet circuit, whereupon the wipers 360, 361, and 362 start rotating in search of an idle trunk line. As is well known, the rotary magnet interrupts its own circuit and also the locking circuit of the test relay 354 at every energization, the contacts in the latter circuit, however, being short-circuited by the test or private wiper 361 While passing over busy or grounded test contacts. As soon, therefore, as the test Wiper reaches an ungrounded test contact the armature of test relay 354 falls back and opens the rotary magnet circuit, thereby bringing the wipers to rest upon the contacts of an idle trunk line, assumed to be in this case the contacts 363, 3 6i, and 365. Upon deenergizing, the test relay 354 closes a circuit for the line switching relay 353, which latter relay disconnects the conductors 327 and 328 from the windings of the line relay 350 and extends them by way of wipers 360 and 362 and bank contacts 363 and 365 to the line relay 375 of the selector E.

The line relay 375 is now energized over a circuit including the conductors 327 and 328 and, upon attracting its armature, closes an energizing circuit for the slow acting relay 376. Relay 376, upon energizing, completes a holding circuit for the line switching relay 353 of the selector E over the following path: ground at G, contact springs 378 and 377, bank contact 364, wiper 361, Contact springs of relay 354, and winding of relay to battery B The operator at the No. 1 exchange may now operate her calling device S in accordance with the second digit of the desired number, the resulting interruptions being effective at this time to cause deenergizations of the line relay 375 of the selector E. The selector E is accordingly operated in well known manner and substantially as described in the ease of selector E to raise the wipers 380, 381, and 382 until they stand opposite the horizontal level which contains terminals of trunk lines extending to the desired subgroup. After the level selection has been accomplished the wipers are automatically rotated to select an idle trunk line, and the trunk line selected is assumed to have been in this case the trunk line extending to the connector H. Through the medium of the line switching relay 879 the line conductors 327 and 328 are then extended by way of wipers 380 and 382 to the line relay 400 of the connector H. The line relay 400, upon energizing, completes a circuit including slow acting relay 401, which relay, upon attracting its armature, completes a. holding circuit for the line switching relays in the selectors E and E in the well known manner.

The operator at the No. 1 exchange may now manipulate her calling device S in accordance with the last two digits of the desired number, resulting now in two series of denergizations of the line relay 400 of the connector H. Under the control of the line relay 400, the wipers 416, 417, and 418 are raised by the vertical magnet 408 and rotated by the rotary magnet 409 until they arrive at contacts which are terminals of the line of substation A. After each series of impulses the private magnet 403 is controlled through the medium of the slow acting relay 402 (in series with the operating magnets), whereby the side switch wipers 412, 413, 414, and 415 are advanced first to second position and finally to third position (it being assumed that the line of substation A' was idle when called).

As side switch wiper 413 comes into its third position, a circuit is completed from ground at G" by way of wiper 417 and bank contact 419 to the holding winding 420 of line switch C. Upon energizing, the hold ing Winding operates the cut-off armature 421, whereby the line conductors of substation A are disconnected from their connections in line switch C. Ground from G also extends to multiple contacts similar to contact 419 in the banks of other connectors of the group, thereby making the line busy to other calls. By the advance of side switch wipers 414 and 415 to their third positions the connection is completed to the called line, relay 405 being (lecncrgized. By the advance of side switch wiper 412 to its third position a circuit is completed for the ringing relay 404., which is operated intermittently thereafter by the interrupter I to signal the subscriber at substation A. When the called subscriber removes his receiver in response to the ringing of his bell a circuit is completed in the well known manner for the double wound back bridge relay 410 (ringing relay 404 being temporarily deiincrgizcd) which relay, upon energizing, reverses the incon'iing line conductors (of no particular consequence) and also CUITlPlCiPS a circuit for the ring cut-off relay 400. The ring cut-off relay, upon attracting its arma ture, locks itself to grol'lnd at and at the same time opens the circuit of the ringing relay 404. 7

At the No. 1 exchange, when the operator has completed the dialing of the required number she may restore her calling device key K thereby making the calling device S available for use in other connections. The connection with substation A may be completed at once or the operator may wait for the response of the called subscriber, the method adopted depending ordinarily upon whether it is only required to connect with a certain substation in the No. 2 exchange or whether a. certain particular person there is wanted. Assuming the latter to be the case, the operator first ascertains that the proper person is at the telephone in the distant exchange, then inserts the answering plug of the cord circuit P in jack J, and operates the ringing key K. By the insertion of the plug in jack J a circuit is com leted which may be traced from ground at by way of low resistance sleeve relay 35, sleeve of plug. sleeve of jack J, conductor 16, and cut-oil winding 48 of line sWit-ch C to battery B". The cut-off armature 49 is thereby operated to disconnect the line conductors 12 and 13 from their connections in line switch C. A branch of the above circuit extends over conductor 20 to multiple contacts in the banks of connector switches having access to the line of substation A through the medium of normal conductors 21 and 22, thereby making-the line of substation A busy to in coming automatic calls.

In response to the ringing of his bell the callingsubscriber at substation A may now remove his receiver from the hook, when the required connection will have been completed. Current for the transmitter at the calling substation is supplied through the windings of the supervisory relay 36 of the cord circuit P, while current for the transmitter of the called substation is Supplied through the windings of the double wound back bridge relay 410 of the connector H. The complete path for voice currents has been drawn in heavy lines and should be upparent without further explanation.

When the conversation is finished both subscribers will replace their receivers.

Upon replacing the receiver at substation A" the relay 36 is decnergized, thereby lighting the supervisory lamp L. By this means the operator is informed that the conversation is at an end, whereupon she may remove both plugs of cord circuit P from the jacks. The removal of the plug from jack J" removes ground from conductor 16, whereby the individual apparatus associated with substation A is restored to normal condition. The removal of the plug from jack J* breaks the circuits of relays 103 and 100 (Fig. 2). Following the deenergization of relay 100 the various relays in the quadruplex equipment in Figs. 2 and 3 are deenergized in the same order in which they were energized. as described in the foregoing, until finally the relay 128 (M, Fig. 3) is denergized. It will be clear that this results in the breaking of the circuit of the line relay 400 of the connector H, whereupon all the automatic switches are restored to normal position in the well known manner.

If the line of substation A had been busy when called, the connector H would have operated after the final series of impulses to connect a lead from the busy signaling machine N with one side of the calling line, the side switch wipers being held in the second position for this purpose and to prevent con nection with the called line. Upon perceiving the busy signal, the operator at the dis tant exchange removes the plug from jack J whereupon the apparatus is restored to normal as hereinbefore described.

The connection which has just been described was established by means of what is commonly known as the neutral side of the quadruplex. It will be evident that a similar connection might have been established at the same time or at any time thereafter over toll line 101102, using the polar side of the quadruplex for controlling the automatic switches at the No. 2 exchange. To make this perfectly clear the operation will be briefly described as follows: When the operator inserts the plug of a cord circuit similar to cord circuit P in jack J a circuit is completed for relay 190 over the sleeve of the cord. Relay 190, upon energizing, connects the relay 191 across the tip and ring conductors of jack J lights the busy lamp L and disconnects the drop 192. Upon throwing the calling device key in the cord circuit, relay 191 is energized and, upon attracting its armature, completes a circuit including relays 150, 151, and 153 in series.

Relay 153 is common to both neutral and polar sides of the quad, and its function evidently is to shift the line circuit from ground over to the generators whenever a call is being made from the No. 1 exchange to the No. 2 exchange. Relays 150 and 151 operate to shift the working line from the generators of negative polarity to the gencrators of positive polarity. ()r in other words, when relays 150 and 151 are energized, current is supplied to the line either from generator 183 or generator 186, depending on whether or not the neutral side of the quad, is being used: It follows then that inasmuch as the direction of current flow in the line is reversed, the polar relay 256 at the distant end of the line will be operated to close its contact whenever relays 150 and 151 are operated. The clo- Sure of its working contact by the polar relay 256 operates the relays 193 and 194, the latter relay performing the same function in respect to trunk conductors 323 and 324 as did relay 128 (M*, Fig. 3) in respect to trunk conductors 327 and 328. It will now be plain that interruptions of the circuit of relay 191 will result in deenergizations of relays 150 and 151, these relays by the successlve retractions of their armatures causing reversals of the line current. The polar relay 256 is responsive to such reversals to control a selector switch through the medium of rela 194 and trunk conductors 323 and 324. t will be observed that the apparatus at the two exchanges is substantially in duplicate whence it appears that connections may be automatically established by operators in the No. 2 exchange between calling subscribers therein and called subscribers in the No. 1 exchange. The methods by which such connections are established will be plain from the preceding description, since the only essential difference is the difference in direction. f-Furthermore, connections may be established simultaneously over the two toll lines shown in opposite directions as well as in the same direction without interference. Since the operation of quadruplex circuits in general is well known and since I do not limit myself to the particular form of quadruplex shown herein, it is not thought to be necessary to go further into the detailed operation of such circuits to explain how simultaneous connections as mentioned above are established.

Considering now the automatic calling feature of my invention in its broader aspects, it will be seen that the talking circuits, comprising the two physical lines and the phantom circuit are quite independent of the operating circuits. In other words, no talking circuit is necessarily associated with any particular operatin circuit, but each operating circuit may arbitrarily assigned to any talking circuit as desired. To

elucidate further, I might employ the toll line 101102 and the phantom circuit for automatic calling in. both directions, while restricting the toll line 103-104 to manual operation. Or I might employ the phantom circuit for autoi'natie operation in both directions, one of the physical circuits for automatic operation in one direction only, and the other physical circuit for automatic operation in the other direction only. Other combinations will be obvious and need not be specifically mentioned.

I'have mentioned hereinbefore that the toll lines and the phantom circuit shown in the drawings are adapted for manual operation whenever desired independent of the automatic features. In establishing a inanual connection over the toll line 103104, for example, the cord circuit 1 may be used as before except that the calling device key K is not thrown. It follows that relay 38 will not be operatively energized and there fore the circuit of relay 100 (M Fig. 2) will not be closed. 'llheretore the operating circuit for the automatic selector switch sociatcd with toll line 103104 at the dis tant end will not be closed and such selector switch will remain inactive. The key K is a ringing key by means of which signaling current may be projected over the toll line 103104 to actuate the drop at the No. 2 exchange. Since the relay 100 is in bridge of the tip and ring conductors whenever a plug is inserted in jack J the ringincr current used for manual signaling shou d be preferably of rather high frequency so as not to operate relay 100 during the signaling operation. Or, if desired, a bar to alternating currents in the form of an impedance coil might be inserted in the bridge to accomplish the same results. Further details regarding the manual operation are thought to be unnecessary in View of the common knowledge of the subject.

It will be seen from the foregoing that I have devised an eflicicnt and comprehensive system of automatic calling over phantomed long distance lines by which auto matic connections may be set up and released at will by a toll operator without in any way interferin with existing connections and without estroying the normally quiet and balanced condition of the lines.

While I have found it convenient in explaining my invention to show a certain specific embodiment thereof, I do not wish to be held strictly to the exact form disclosed, for various adaptations of the same will doubtless occur to persons skilled in the art. I desire, therefore, to include and have protected by-Letters Patent all forms and modifications of my invention which may come within the scope of the appended claims.

What I claim as my invention is:

1. In a telephone system, a calling and a called line, a trunk line, means for connecting said lines via said trunk line, said means including an aliitomatic switch having ac- (088 to the called line, an operating circuit for said switch including the conductors of said trunk line in parallel, a controlling relay for said switch in said circuit, a source of current For said circuit, and means for re versing the direction of current flow in said circuit at intervals in accordance with digits in the number of the called line to operate said controlling relay, whereby said switch may be operated to complete the said con nection. Y

2. In a telephone system, a line, an electromagnetic automatic trunking switch for said. line. a control circuit for said switch including cmiductors of said line, a second line accessible to said switch, a relay in said circuit responsive only to current flow in a certain direction, sources of current of opposite polarity, means for closing said circuit through one of said sources to operate said relay. and means for intermittently substituting the other source in said circuit to cause denergizations of said relay, whereby said switch may be operated to connect said lines, a second automatic trunking switch, said second switch for said second line, said relay for also operating said second switch to close a circuit with another line.

3. In a telephone system, a calling and a called line, a trunk line, means for connecting said lines via said trunk line, said means including an automatic switch having access to the called line, an operating circuit for said switch, a controlling relay in said circuit, a source of current of high potential, a source of current of low potential, means for inserting said high potential source in said circuit to operate said relay, and means for substituting said 10w potential source for said high potential source at intervals to cause deener izations of said relay, whereby said switc may be operated to complete the said connection.

4. In a telephone system, a line, an automatic switch for said line, an operating circuit for said switch including the conductors of said line in parallel, a second line accessible to said switch, a source of current of high potential, a source of current of low potential, a controlling relay for said switch in said circuit, means for closing said circuit through the said high potential source to operate said controlling relay, and means for intermittently substituting the said low potential source for the said high potential source to cause deenergizations of said controlling relay, whereby said switch may be operated to connect the two lines.

5. In a telephone system, a calling and a callcdline, a trllnlg llne, means for connecting said lines via said trunk line, said means including an automatic switch having access to. the called line, anoperating circuit, a source of current for said circuit, controlling relay in said circuit responsive to current impulses of a particular character therein to operate said switch, another switch, a connection established over another line by means of said other switch, a second relay in said circuit for inaintaining said connection, said second relay irresponsive to said impulses, and means for transmitting said particular character of current impulses I over said circuit, whereby said first switch may be operated toconnect; the said calling and called lines without affecting the connection over the said other line.

6. In an automatic telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a phantom circuit superimposed on said lines, an automatic switch at the second exchange for each of said lines, a common controlling circuit for said switches superimposed on said phantom circuit, means at, the first exchange for transmitting current impulses of different character over said controllin circuit, and a controlling relay for each o said ,switches'in said controlling circuit, saidlrelays each responsive only to current impulses ofa particular character. a 7

7. 111 an automatic telephone system, a first exchange and a second iexchangaa pair fif lines connecting said exchanges, a Fphan tom circuit superimposed on said lines, van automatic switch at the second exchange for each of said lines, a common controlling circuit for said switches, said controlling circuit including theconductors of said lines in parallel, means at the first exchange for transmitting current impulses of different character over said controlling circuit, and a controlling relay for each of said switches in said controlling circuit, said relays each responsive only to current impulses lot-17a particular character.- 1 a 8; In; an automatic telephone system, a firstexchange and a second exchange,a airof lines connecting said: exchanges,.a1 p antoni circuit superimposed on said, dines, an automatic switch at the second exchange for each of; said lines, a common controllingcine euit for said switches superimposed on said pl autonrcircult, a source ojficurrentjor sa d controlling circuit, means at, the first exchange for periodically reversing the direc: 1'

tio n of current flow in said controlling cinuu; m ans at t e r hene emp ia odically increasing the current flow: ire said controllingv circuit, and Acontrollingi neleys in .said IGOll-tI'OIliflg circuit xfor said automatic sw tcheaione of, said relays res 0I181V6O4PB-- versalscteunrentiand, the ot er relay re ft-ar uses si ca e incremen ed cu rents u l a 9- a an, metastat c teleph ne sys m li pair of 111165, anautoniat c SWlWh, for each, line ton -extending connections therefrom, 5a common controllii ,circuit forsaidswitches, including; .the tal ing conductors otisaid lines, means for transmitting current ,in r pulses of differentcharacter over said con? y trollin circuit,,and a controllingnelay for each 0 7 said switches in said continuing-cite, w, cuit, said relays each responsive on1ytocur-75 1 rent iinpulsesota particular character M 10. In an automatic telephone system, a pair oflines, an automatic switch forqeachi line forexten'ding connections therefrom, a common controlling circuit forgsaid switches .80, 1, including the conductors 0;E saiddines, la, n source of current, or, said circuit 'auqona trolling relay in said circuit for oneof said switches, said relay responsive only to re versals of current therein to operate ,itsas- 85,, sociated switch, a second controlling relay in said circuit for the other of said swiches, said second relay responsive only to in creased current impulses therein, to operate its associated switch, and means for, trans- 90, inittin reverse current impulses or, in: crease current impulses over 7 said controlling circuit, whereby said switches, may, beoperated independently, i

11." In an automatic telephone; pair of lines, an automaticswitch fonieach line for extending connections therefrompa common controllin circuit for saidlswitchesm including the tal ug conductors of said? lines, a source of current for saidlcircuit, e1 9; controlling-relay in said circuit for? one..of said switches, said relay responsive enlyto, current impulses in said circuit of aparitcir lar character for operating its associated switch, a second controlling relay inisaid 1 5,? circuit for the other of said switches, said second relay responsive only currentim-i, i pulses in said circuit of a difierent charred ter for operating its associated switch, and!1 means for tran'smittinawover said controlling 19. circuit either ofltwo differentkindsiotuim pulses, whereby said switches may hampers i med-independently. i a L, y;

12. In Z an? automatic telephone system, is

first; cachangciand a second exch ns tazpaim 11 5 of. li es connecting said: exchanges, a, ual, gack for each ime in each e hange a ti 5 autom artie switch; for each line a h m l? wexchange, a controlling circuit for snid switches! in uding $12110 ,toendu m s pt said 9 lines, a source; (of curren for said? emtuib, la, g; controlling relay in said circuit resppnsine y to ent imp lses herein-i chat particnwg l n -ch r t r: :ter p eg ne at. said: u;

switches, asecend controlling relaying ms; 1,253,, ci uitzvespensweionlv to cum utiampi lsrc-n therein 1 of re; difi'ereutwharaeterufon opera 1' 5 ating: the other: 0t said -W1thr means- .tom 5,: transmitting-7 over fi ld Girl-711 b e h r r of 'tWQ I diijarcnttle ds rtimr ssa-iwh m niaatdal fin switches may be operated independently, and means associated with each line at the second exchange for disconnecting such line from its associated jack and for connecting it instead with talking conductors of its associated switch when the said switch is opcrated.

13. In an auton'iatic telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a manual jack for each line in each exchange, an automatic switch at the second exchange for each of said lines for extending connections therefrom, a controlling circuit for said switches includin the conductors of said lines, a source 0 current for said circuit. a controlling relay in said eimuit responsive only to reversals of current therein for operating one of said switches, a second controlling rela in said circuit responsive only to increase current impulses therein for operating the other of said switches, means for transmitting reverse current impulses or increased current impulses over said control ling circuit, whereby said switches may be operated independently, and means associated with each line at the second exchange for disconnecting such line from its associated jack and for connecting it instead with talking conductors of its associated switch when the said switch is operated.

14. In an automatic telephone System, a first exchange and a second exchange, a pair of lines connecting said exchanges, a manual jack for each line 111 each exchange, an automatic switch for each line at the second exchange, a controlling circuit for said switches including the conductors of said lines, a source of current for said circuit, a controlling relay in said circuit responsive only to current impulses therein of a particular character for operating one of said switches, a second controlling relay in said circuit responsive only to current impulses therein of 1a difi'erent character for operating the other of said switches, means for transmitting over said circuit either of two different kinds of impulses, whereby said switches may be operated independently, a busy signal associated with each jack at the second exchange, and means for operating the busy signal corresponding to any line when the automatic switch therefor is operated.

15. In an-automatic telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a manual j-ackfor each line in each exchange, an automatic switch at the second exchange for each of said lines for extending connections therefrom, a controlling circuit for said switches including the conductors of said line, a source of current for said circuit, a controlling relay in said circuit responsive only to feversalsof. current therein for operating one of said switches, a second controlling relay in said circuit responsive only to increased current impulses therein for operating the other of said switches, means for transmitting reverse current impulses or increased current imiulses over said controlling circuit, where y said switches may be operated independently, a busy signal associated with each jack at the second exchange, and means for operating the busy signal corresponding to any line when the automatic switch therefor is operated.

16. In an automatic telephone systen'i, a first exchange and a second exchange, a pair of lines connecting said exchanges, a manual jack for each line in each exchange, an auto matic switch for each line at the second exchange, a controlling circuit for said switches including the comluctors of said lines, a source of current for said circuit, controlling relay in said circuit responsive only to current impulses therein of a par ticular character for operating one of said switches, a second controlling relay in said circuit responsive only to current impulses therein of a different character for operat ing the other of said switches, means for transmitting over said circuit either of two difi'erent kinds of impulses, whereby said switches may be operated independently, a drop for receivin signals in bridge of each line, and means or disconnecting the drop from the line when the switch associated therewith is operated.

17. In an automatic telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a manual jack for each line in each exchange, an auto matic switch at the second exchange for each of said lines for extending connections therefrom, a controlling circuit for ,said switches including the conductors of said lines, a source of current for said circuit, a controlling relay in said circuit responsive only to reversals of current therein for operating one of said switches, a second controlling relay in said circuit responsive only to increased current impulses therein for operating the other of said switches, means for transmitting reverse current impulses or increased current impulses over said controlling circuit, whereby said switches may be operated independently, a drop for receivin signals in bridge of each line, andmeans or disconnecting the drop from theline when the switch associated therewith is operated.

18. In an automatic telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a manual jack for each line in each exchange, an automatic switch for each line at the second exchange, a controlling circuit for said switches including the conductors of said lines,"a source of current for said circuit, a controlling relay in said circuit responsive only to current impulses therein of a particular character for operating one of said switches, a second controlling relay in. said circuit responsive only to current impulses therein of a different character for operating the other of said switches, means for transmitting over said circuit either of two different kinds of impulses, whereby said switches may be operated independently, local lines in each exchange, and manual connecting means whereby connections may be established between local lines via said first lines without operating the automatic switches associated therewith. 19. In an automatic telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a manual jack for each line in each exchange, an automatic switch at the second exchange for each of said lines for extending connections therefrom, a controlling circuit for said switches including the conductors of said lines, a source of current for said circuit, a controlling relay in said circuit responsive only to reversals of current therein for operating one of said switches, a second controlling relay in said circuit responsive only to increased current impulses therein for operating the other of said switches, means for transmitting reverse current impulses or increased current impulses over said controlling circuit, whereby said switches may be operated independently, local lines in each exchange, and manual connecting means whereby connections may be established between local lines via said first lines without operating the automatic switches associated therewith.

20. In an automatic telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a phantom line superimposed on said lines, a manual jack for each of said lines and for the phantom line in each exchange, an automatic switch for each line of said pair at the second exchange, a controlling cir cult for said switches superimposed on said phantonrline, a source of current for said circuit, a controlling" relay in said circuit responsive only to current impulses of a particular character therein for operating one of said switches, a second controlling relay: in said circuit 'fesponsiveonlyto cure rent impulses of a different charactertherewinpfor operating the other ol' said switches, means for transmitting over sald cirauit either of two difi'erent kinds of impulses, whereby sai-d switches may be operated independently, loxal lines in each exchange,

wand; manual, .connectin means wherehy conlletljlQlIS may be esta lished between local lines via said first lines or said phantom line without operating the said automatle switches.

21. In a telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, an automatic switch for each line in each exchange, a common controllin circuit for said switches, a controlling rlay in said circuit for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular character, similar controlling relays in said circuit for the switches at the second exchange, and means at each exchange for transmitting two different kinds of current impulses over said circuit, whereby the switches at the other exchange may be operated independently.

22. In a telephone system, a, first exchange and a second exchange, a pair of lines connecting said exchanges, an automatic switch for each line in each exchange, a common controlling circuit for said switches, a source of current for said circuit, a controlling relay in said circuit at the first exchange responsive only to reverse current impulses for operating one of the switches thereat, a second controlling relay in said circuit at the first exchange responsive only to increased current impulses for operating the other of said switches, similar controlling relays in said circuit tor the switches at the second exchange, and means at each exchange for transmltting reverse current impulses or increased current-impulses over saidcircui't, whereby the switches at the other exchange may be operated independently.

23. In a telephone system, a first exchange and a second exchange, a pair of lines connecting said exohan es, a phantom line superimposed on sai lines, an automatic switch for each line of said pair in each exchange, a common controlling circuit for said switches superimposed on said phantom line, a controlling relay for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular character, similar controlling relays in said circuit for the switches at the second exchange, and means at each exchange for transmitting two different kinds of current impulses over said circuit wheree y the switches at the other exchange may be operated independently. a

24. In a telephone system, a first exchange,

and a second exchange, apair of lines connecting said exchanges, an automatic switch for each line in each exchange, a common controllin circuit for said switches, a controlling re ay in said circuit for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular-character, similar controlling relays in, said circuit for the switches; at the second exchange, means at each exchange for-transmittin two 'difierent kinds of cur-i rent impulses over said circuit, whereby Ill the switches at the other exchange may be operated independently, and menus at each exchange whereby the controlling relays at the exchange from which impulses are being transmitted are pre'wnted l'roin rcspoiulimi; thereto.

25. In a telephone system, a first exchange and a second exchange, n pair or lines connecting ,caid exchange an mitoinnli switch for each line in each exchange, a connnon controlling circuit for said switches, a source of current for said circuit, a controlling relay in said circuit at the first exchange responsive only to reverse current; impulses for operating one of the switches thereat, a second controlling relay in said circuit at the first exchange responsive only to increased current impulses for operatin the other of said switches, similar controlling relays in said circuit for the switches at the second exchange, means a each exchange for transmitting reverse current impel res or increased current impulses over said circuit. whereby the switches at the other exchange may be operated indc 'icndently, nd inean at each exchange whereby the control ing relays at the exchange from which impulse 1 are being transmitted are prevented from responding thereto.

26. In a telephone system, a first exchange and a second exchange, a pair of lines con necting said exchanges, a phantom line superimposed on said lines, an automatic switch for each line of said pair in each exchange, a. common controlling circuit for said switches superimposed on said phantom line, a controlling relay for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular character, similar controlling relays in said circuit for the switches at the second exchange, means at each exchange for transmitting two different kinds of current impulses over said circuit, whereby the switches at the other exchange may be operated independently, and means at each exchange whereby the controllin relays at the exchange from which impu ses are be ing transmitted are prevented from respond in thereto.

7. In a telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, an automatic switch for each line in each exchange, a common controlling circuit for said switches, a con trolling relay in said circuit for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular character, similar controlling relays in said circuit for the switches at the second exchange, means at each exchange for transmitting two different kinds of current impulses over said circuit, whereby the switches at the other exchange may be opernted independmIIly, n manual jzn'li For ouch line H] each exchange l)il;-; signals associl ll \Vllll the lnl'liri r rrzwno n|n|p to the lines ol soul pull, and nuw a l'nr ogn-lxitil'lff the hu:'-;y iinnnl nl he'll ends ol n llnn when one 01 the antonmtn switches nssoriated lineu t! n operated.

28. in a li-lophoi e system, n lnsi exchange -1i"f l iv'nnzl evrhnnrlpun 'il' lines conwi l ei ran1- i nm 1' mid circuit,

' at "h" 2 y be oncrated indcpendently a manual ;k for each line in each exchange, busy signals associated with the jacks corresponding to the lines of said pair, and means for oper ating' the busy signal at both ends of a line when one of the automatic switches associated therewith is operated.

29. In a telephone system, a first exchange and a second exchange, a pair of lines conectinnsaid exchanges, a phantom line superimposed on said lines, an automatic Wit h for ach line of said pair in each exangfn. 1: common eontrollinncircuit for "d mvitchcs superinnposed on said. Diuinton'i e cr'mtrolliuq' rrliy r i h at mid itehes in th firs ef-I anur said relays csponsivc only to current impulses of a particular character. similar controlling relays in said circuit for the switches at the second exchange, means at each exchange for transmitting two different kinds of rurrent impulses over said circuit, whereby the switches at the other exchange may he operated independently, a manual jack for each line in each exchange, busy signals associated with the jacks corresponding to the lines of said pair, and means for operating the busy signal at both ends of a line when one of the automatic switches associated therewith is operated.

30. In a telephone system, a first exchange and a second exchange. a pair of lines conne ting said exchanges, an automatic switch for each line in each exchange, a common controlling: circuit for said switches, a controlling relay in said circuit for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular character, similar controlling relays in said time for the switches a the switches'at the other exchange may be oper- "irte'd independently, a manual jack 'fo'r each line in each exchange, and means associated with. with line of, said air at each exchange whereby wheat-saute exchange operated the line associated therewith "disconnected 1 from its" ajk in that exch e and is connected instead to talkin crhi fuctors of the operated switch.

31. n a telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, an automatic switch for each line in each exchange, a common controlling circuit for said switches, a source of current for said circuit, a controlling relay in said circuit at the first exchange responsive only to reverse current impulses for operating one of the switches thereat, a second controlling relay in said circuit at the first exchange responsive only to increased current impulses for operating the other of said switches, similar controlling relays in said circuit for the switches at the second exchange, means at each exchange for transmitting reverse current impulses or increased current impulses over said circuit, whereby the switches at the other exchange may be operated independently, a manual jack for each line in each exchange, and means associated with each line of said pair at each exchange whereby when an automatic switch in either exchange is operated the line associated therewith is disconnected from its jack in that exchange and is connected instead to talking conductors of the operated switch.

32. In a telephone system, a first exchange and a second exchange, a pair of lines connecting said exchan es, a phantom line superimposed on sai lines, an automatic switch for each line of said air in each exchange, a common controlling circuit for said switches superimposed on said phantom line, a controlling relay for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular character, similar controlling relays in said circuit for the switches at the second exchange, means at each exchange for transmitting two different kinds of current impulses over said circuit, whereby the switches at the other exchange may be operated independently, a manual jack for each line in each exchange, and means associated with each line of said pair at each exchange whereby when an automatic switch in either exchange is operated the line associated.

therewith is disconnected from its jack in that exchange and is connected instead to talking conductors of the operated switch.

33. In a telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, an automatic switch for each line in each exchange, a common controlling circuit for said switches, a controlling relay in said circuit for each of said switches in the first exchange, said relays each res 'onsive only to current impulses of a arse 'ar character, similar controlling relays insaid circuit forthe swi hes at the second exchange, means at eac 1 exchange for transmitting two different kinds of current impulses over said circuit, whereby the switches at the other exchange may be operated independently, a manual jack for each line in each exchange, local lines in each exchange, and manual connecting means whereby connections may be established between local lines via said first lines without operating the automatic switches associated therewith.

34. In a telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, an automatic switch for each line in each exchange, a common controlling circuit for said switches, a source of current for said circuit, a controlling relay in said circuit at the first exchange responsive only to reverse current impulses for operating one of the switches thereat, a second controlling relay in said circuit at the first exchange responsive only to increased current impulses for operating the other of said switches, similar controlling relays in said circuit for the switches at the second exchange, means at each exchange for transmitting reverse current impulses or increased current impulses over said circuit, whereby the switches at the other exchange may be operated independently, a manual jack for each line in each exchange, local lines in each exchange, and manual connecting means whereby connections may be established between local lines via said first lines without operating the automatic switches associated therewith.

35. In a telephone system, a first exchange and a second exchange, a pair of lines connecting said exchanges, a phantom line superimposed on said lines, an automatic switch for each line of said pair in each exchange, a common controlling circuit for said switches superimposed on said phantom line, a controlling relay for each of said switches in the first exchange, said relays each responsive only to current impulses of a particular character, similar controlling relays in said circuit for the switches at the second exchange, means at each exchange for transmitting two. difi'erent kinds of current impulses over said circuit, whereby the switches at the other exchange may be operated independently, a manual jack for each line in each exchange, local lines in each exchange, e in] manual connecting means win-reby ((JIHIUCiiUHH may he established beM-veen. iemi lines ViiL said first lines or said phanieln line without operating the said uutw mat is switches.

36. A rehiy emitmiied over :1 trunk by the use 0' high vuimge battery and a 10W volt- :ige haitm-y, :1 line, an autoumiie progressively lliflwlilifl switch for extending said line to another line (to form :1 mlkinig cireuit over the two lines, send relay eentaru ling sand an lmnutn: switch over two sides of said first line in series when operated as specified.

bigned by me 21L (jhlcugo, (100k county, State of Illinois {his eleventh day of March, 1916.

ARTHIVTR BESSEY SMITH.

Copies of this patent may be obtained for five Cents each, by addressing the Commissioner of Patents, Washington, D. C.

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