US1164479A - Automatic telephone-exchange system. - Google Patents

Description

e. DEAKIN. v AUTOMATIC TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED OCT-25, 19H.

Patentmad Dec. 14 1915.

WIMN:

GERALD DEAKIN, 0F BERKELEY, CALIFORNIA.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

rename.

Specification of Letters Patent.

Patented Dec. I l, wild.

' Application filed October 26, 1911; Serial No. 656,912.

To all whom it may concern Be it known that I, GERALD DEAKIN, a citizen of the United States of America, and aresident of Berkeley, Alameda county, California, have invented a new and useful Improvement in Automatic Telephone-Exchange Systems, of which the following is a specification.

My invention pertains to an improved electrical circuit for a switch adapted to es= tablish automatically, connections between subscribers in a telephone exchange system. At the present time the switches commonly used in extending and completing connections in automatic telephone systems are divided into two general classes. In the first class are those switches adapted to extend or trunk the connection from the terminus of the calling subscribers line to the next switch which switch either completes the connection or extends it to another similar switch, to be further extended or trunkedr to extend or complete a connection, as occasion demands.

My improved electrical circuit applies to no particular form or design of switch jfrom a mechanical viewpoint, but may be applied to anV switch whose parts permit of adaptation to mv circuit.

As before stated, in the automatic telephone systems now in general use, a connector completes the connection between thc'calling ,subscribers line and called subscribers line while a selector' establishes automatically, the connection between the terminus of the calling subscribers line and the proper connector. Connectors are usually arranged to make connection with any one of a group of 100 lines. Thus in a telephone exchange system not exceeding one hundred (100) lines, the connectionbetween the called and calling line may be'made by a connector without the aid of a selector;- Where the number of lines in an exchange systenr exceeds one hundred (100) but m t one thousand (1000') a selector must first be stations in such a group the rate of calling is very high as compared with the rate of calling to thestations outside of the group. These groups include local private exchange systems and for the most part do not exceed or stations in capacity. In such groups as these, it is very desirable that local intercommunication be afiorded by a means involving the calling of two digits only. It is also necessary that the subscribers in .each group be able to call any other subscriber forming part of the main exchange system. My improved electrical circuit provides for this. A switch so .ar-'

rect-ly as would a connector of the usual type, but when establishing a connection with a subscriber outside of the group with which it is associated, will act as a selector and will afford the means of trunking or extending the call to the next trunking switch or connector as the case may be. In my improved circuit I provide a means for restricting any local station to local service, exclusively, thus making it impossible for'a local station to restricted to effect a connection with a subscriber outside of its particular group. I also provide for a means for registering the number of completed calls made to subscribers outside of the group in which thecall originates.

In the preferred form of my invention I arrange the switch so that it normally operates as a connector, and is converted into a ranged will complete a local connection diselector when a pre determined number or when the digit 0 is called would be so arranged as-to cause the circuit of the switch coming to the subscribers station, A. G repupper row would afiord a choice of a plurality of trunks, to a central oillce, the switch when Converted into a selector being arf ranged to rotate or otherwise select the first idle outgoing trunk.

F or the sake of clearness I willmake use of, in describing my invention, switches of the general physical form described in United States Patent No. 815321, granted to Messrs. A. E. Keith, John and Q J. Erickson, on March 13,1906.

In the accompanying drawings, Figure 1 illustrates my improved combination connector and selector circuit; also an associated subscribers line and telephone circuit. In Fig. 2 is shown a skeleton outline of a. second subscribers line and .telephone circuit. In Fig. 3 are shown two trunk line conductors terminating on a bridged relay of a selector orother switch at a main eX- change. In Fig. '3 is shown a bridged relay having its battery connections reversed so as to cause current to'flow in the opposite direction in the-calling line, for a purpose hereinafter referred to.

At A in Fig. 1, is shown a simple form of subscribers station telephone circuit consisting of a transmitter, receiver, ringer, condenser, switchhook and at 3 contact springs controlled by the calling dial and adapted to open the ine circuit intermittently when in operation." V, P and R represent the subscribers line contacts, which are adapted to be engaged in electrica connection by the switch wipers, VW, PW' and RWV respectively. 17, 18, 19, 20 and 21 represent side switches controlled by the electro-magnet PM, eachside switch being arranged to make alternately three connections, indicated by the side switch number suflixed by the letters a, b and. c. D represents a cut ofl relay adapted to remove the switch from connec tion with the subscribers line on calls inresents the controlling winding of a service meter connected serially in one side of the subscribers line. VM and RM represent electro-magnets controlling the vertical and rotary motion of the switch respectively. J represents the release electro-magnetand is controlled by the shaft contact 30, and the slow-acting relay L. Shaft contact 30 is arranged to close whenever the shaft of the switch to which wipers VW, RW and PlV are fastened, is out of its normal position. K represents a line relay controlling the operation of the vertical and r tary magnets VM and RM respectively, tl acting relays L and M.. H and S represent relays controlled by shaft contact springs 31 and 33. These rela s when energised, ar arranged to convert tie electrical. circuit of the'switch from a circuit adapted to the including V and V", 'tacts includin P and P and a rou of rough slowestablishment of local connections as done of my invention it engages a fixed projection on the shaft and is moved only when the shaft is stepped up to the last row. N represents a retardation coil of high resistance and impedance. E represents a'supervisory relay and affords the means of holding the switch busy during trunked connections.

. RR represents the ringing relay-controlling swinging'springs 66 and 61. Q represents the called line relay. F represents a relay adapted to give the calling subscriber a busy signal should the line called be busy. Relay I operates as an interrupter on trunk connections and causes the rotary magnet RM to rotate the wipers over busy trunk contacts.- 39 and 40 represent condensers. 64 and 63 represent contact springs controlled by the private magnet PM.

In Fig. 2, V, P and It represent line contacts of a second subscribers line adapted to be engaged by wipers VW, PW and RW', Fig. 1, respectively. D represents a cut oil relay similar to that shown at D in Fig. 1. At B is shown a simple form of subscribers station telephone circuit such as is shown at A in Fig. 1.

In Fig. 3, V", P and R" represent line contacts of a trunk terminating at a 'main oflice on a bridged relay, C. The line contacts are adapted to be engaged by wipers VW, PlV and RlV, F ig. 1, respectively. The contacts V, P" and R of the trunk lines are in the same group with the corresponding contacts V, P and R, respectively, of.

thesubscribers lines, that is, there are three groups, each comprising several single rows of contacts, namely, a group of tip contacts a group of test consleeve contacts including R and R.

Each of theside switches previously referred to consist of a movable contact spring and three fixed contacts, the whole being controlled by the electro-magnet PM, Fig. 1, and so designed that the side switches are normally held in what is called their first or normal position under the tension of a spring or springs which tend to force them into their second and third positions. The electro-magnct, PM, when first energized and then deenergized, operates an escapement, causing the side switches to step from their first or normal position into their second position. In other words, the movable springs are caused to break connection with the first series of fixed contacts and make connection with the second series of fixed contacts. When the private magnet is cnengized and deenergized a second time, it

causes the side switches to step from their second into their third or final position. The side switches are caused to resume their normal position by the energizing of the release magnet which magnet in addition to forcing the side switches back into their normal position, releases the switch shaft to which the wipers are attached, allowing the shaft to resume its normal position. Contact between springs 63 and 64; is adapted to open whenever electro-magnet PM is energized.

The operation of a switch arranged according to my improved circuit is as follows: We will first consider the case in which one local station desires to establish a connection with another local station. In this case station A, Fig. 1, may be considered as the call ing station and station B, Fig. 2 as the called station. To call, the subscriber at station A removes the receiver from the switchhook thereby closing a circuit through his telephone set from earth 1, through battery 2, one winding of K, 37', 60, T 5, conductor T of calling line, telephone set at station A including calling device contacts 3, conductor T of the calling line, 4, Winding oil meter controlling winding G, 13, 12, the other winding of K to earth again at 1.

, Current flows through this closed circuit and energizes relay K. Metering apparatus at G does not operate as it is polarized or otherwise arranged to operate onlywhen current flows through the line in the reverse direction. The operation of relay K energizes relay 1., a circuit being closed from 1, through 28, 27, winding of L, 2 to 1. lhe switch remains in this condioperated. This dial, when operated, rapidly opens andcloses the line circuit at 3. The

number of times the line circuit is opened depends upon the digit called on the dial. For example, it digit 5 is called, the circuit is broken 5 times. The speed of these interruptions is so adjusted. as to permit relay K to follow them, but not thesluggish relays L and M. In this way a circuit is closed at each interruption from 1, through 28, 29, 25, 2 1, winding of M, winding of 7M, 17*, 17, 2 to 1. The closing of this circuit energizes relay M, also the vertical magnet VM, thereby causing the switch to step up one row or unit. At each of the succeeding openings of the line circuit at 3, the vertical magnet, VM, is caused to step the shaft up one additional row or unit. Following the cessation of the series of interruptions, the

line circuit remains closed t-rou'gh contact 3. Relays K and L remain energized. Relay M due to its sluggish action didnot resume its normal position dotting the opera tion of the dial, but does so: now, its circuit being open between 28 and 29. Relay M when first energized, as previously stated, energizes the electro-magnet PM, a circuit 20 and 21 break contact with 18, 19*, 20 and 2l respectively and make contact with 18", 19 20 and 21 respectively.

When the dial is operated a second time, relays K and M again operate as described in the preceding paragraph, this time, however, the rotary magnet RM, is energized instead of the vertical magnet VM, a circuit being established from 1, through 28, 29, 25, 21, winding of M, 52, 53, 6, 7, winding of RM, 17, 1?, 2 to 1. The switchshai't is rotated one step each time the magnet RM is energized. 1f the proper digits have been called the switch wipers VVV, PW and RW will upon the cessation of thesecond series of impulses, be in electrical contact with the called line terminal V, P, and

B, respectively. The private magnet PM is again energized at the beginning of the second series of impulses and when denergized, causes all side switches to step into their third position, thus connecting 1.7 to 17 is to 18, 19 to 19, 20 to 20 and 21 to 21. When side switch 20 steps into its third position, wiper PW is grounded. In

this way relay 1) is energized, thereby removing a: switch similar to that shown in Fig.1, from connection with called line, as shown in Fig. 2. A circuit is established from 1, Fig. 1, through 20, 20, PW, P,

winding of D, 2 to 1. The grounding of wiper PW in addition to operating cut off relay D makes the called line Fig. 2, busy to all other switches, "as hereinafter described. Side switch 21 places a ground on contact P, thus making the calling line busy to all other switches. The contact made between 17 and 17 causes the ringing delay RR to send out intermittently over the called line, an alternating or pulsating current from ringing generator Y, thereby causing the ringer at station 13 to ring at intervals. To accomplish the above result a closed circuit is intermittently. established from earth 1, through interrupter W, 44, 15, winding of RR, 17, '17, 2 to 1. Whenever relay RE is energized spring 61 breaks contact with (32 and makes contact with 60 and spring 66 breaks contact with 67 and makes contact with 65 thereby causing current to flow from one pole of ringing generator Y, through 60, 61, 9, 10, VW, V, one side of called line, ringer and condenser Mid at station B, opposite side of the called line, R, RWV, 19, 19, 66, 65 to the other pole of generator Y. During the intervals the local circuit is open at interrupter W relay RR is in its normal position, thus when the called subscriber answers, a circuit permitting the How of a direct current is closed through the. telephone set at station B. A direct'current is now caused to flow from 1, through one winding of Q, 64, 63, 62, 61, 9, 10, VVV, V, telephone set at station B, R, RW, 19, 19, 66, 67,51, 50, the other winding of Q, 2 to 1. Relay Q is now energized and locks up during the remainder of the connection, a circuit being established from 1, through one winding of retardation coil N, 18, 18, 46, 47 the other winding of Q, 2 to 1. The operation of'relay Q opens the circuit of relay RR between contacts 44 and 45. This latter relay [therefore remains in the normal position during the remainder of the connection.

The calling subscriber at station A and the called subscriber at station E are now in communication with each other. At the end of the conversation, the connection is released by the hanging up of the calling subscriber at station A. The disconnection is caused by the opening of the line circuit at A, thus deenergizing relay K, which in turn releasesslow-acting relay L, thus energizing the release magnet J, current flowing from 1, through 28, 29, 25, 26, winding of J, shaft contact 30, 2 to 1. The switch now resumes its normal position and opens the release circuit at 30.

The preceding paragraphs describe the method of operation of the switch ,when establishing a connection with a non-busy line. Should the called line be busy, the operation of the switch is the same as previously described, up to the point where the wipers engage the line contacts of the called hne with the side switches in'the second position. It should be noted that contact P in the line terminals of a busy line is connected to earth 1, through wiper P\V of the engaging switch in case the busy line is the called line,

, or through side switch 21 in case the busy line is the calling line. Therefore, whenever a switch, Fig. 1, selects the contacts of a busy line and the side switches are in the second position, a circuit is established from grounded contacts P, Fig. 2, through PW, Fig. 1, 20, 20", 56, 55, winding of F, 41, 42, winding of PM, 2 to 1. The result is that relay F is energized and locks up, a circuit being established from earth 1, through 23, 22, 54, 55, winding of F, 41, 42, PM, 2 to 1. This closed circuit, in addition to energizing relay F, also keeps ene gized the electro-magnet PM, which, as before stated, controls the side switches and local contacts 64 and 63. The result is that the talking circuit connecting the calling line with the wipers VW and called line. To indicate to the calling subscriber that the called line is busy, a busy tone is placed on the calling line by the closing of contacts 57 and 58 on relay F, a circuit being established from a grounded busy tone transformer through conductor 57, 58, 19 19, 66, 67, 39, T, 5 T subscribers telephone set at station A, 3, T 4, winding of G, 13, 12, one winding of K, to earth again at 1. Upon the receipt of the busy tone the calling subscriber hangs up his receiver, thus opening the calling line circuit at station A and allowing the switch to releasc as previously described. It should be said that following the cessation of the second series of interruptions, relay M resumes its normal position, as previously described. Prior to this relay M energized electro-magnet PM, current flowing from 1 through 31, ('58, -13, 42, winding of PM, 2 to 1. Springs 41, 42 and 43 are so adjusted as to cause contact to make between springs 4-1 and 42 before contact is broken between springs 42 and 43. Therefore, when wiper PW engages line contact P when grounded, as is the case when the called line is busy, the circuit through the elctro-magnet PM is not broken when relay M resumes its normal position, but remains closed in series with relay F as previously described.

What has been said thus far applies for the most part to a switch arranged in accordance'with my improved circuit and operated as a connector in completing or attempting to complete directly, a connection between two local stations. My improved circuit as previously stated, also permits the trunking or extending of a call to other switches "for,

the ultimate connection with a distant subtion, the switch is so arranged that when a particular number or digit is called, spring 31 breaks contact with spring (58 and makes contactwith springs 32 and 33. This contact spring 31, may be operated by any part ofthe switch which changes its position, in accordance with the dial interruptions originating at the calling station. We will assume that the tenth or top row of line contacts is reserved for trunks to a central oiiicc. In this case the shaft contacts will be operated when the digit 0 is called. This digit when called interrupts the line circuit ten times,-thus causing the switch shaft to step up ten rows or units, which in the present form of commercial switches, is the top row.

meagre call in response to impulses originating at the calling station and passing through the switch shown in Fig. 1.

. Assume station A desires to make a trunk connection through a central oflice with the trunk line contacts arranged as just described. The operation of the switch during the calling of the digit 0 is the same .as described in the preceding paragraphs.

The movement, however, shaft spring 31 breaks contact with spring 68 and makes contact with 32 and 33, the following changes take place in the circuit of the switch. The windings of relays K and Q are removed from connection with the calling line by the opening of contact between 37 and 60, 50 and 51, 12 and 13 and 9 and 10. Relay E, by the closing of contact between 51 and 69, is placed in series with one side of the'calling line. Wiper VW is placed in direct metallic contact with the calling line by the closing of contact between 10 and 11. Contact is made between 7 and 8 and broken between 6 and 7 thus removing the rotary magnet RM, from the control of line rel'ay K and placing it in series with interrupter T, the function of which is to cause the switch to rotate until a non-busy trunk is selected, after which the side switches step into their second position, opening the circuit of the rotary magnet, thus preventing the further rotation of the switch. This action of the rotary magnet is accomplished in detail as follows: The closing of contact between 7 and 8 energizes interrupter ll and rotary magnet RM, a circuit being established from 1, through 16,- winding of ll, 8, 7, winding of RM, 17*, 17 2 to 1. The switch rotates one step, then the circuit opens between 14 and 16, thus deenergizing bothinterrupter I and electromagnet RM and arrangingthem for a second operation. The switch is prevented from releasing during its rotation by the contact or series of contacts made between springs 14 and 15 on interrupter T. The circuit thus closed energizes slow-acting relay L which being sluggish in operation, does not chatter during the interruptions. At the beginning of the call relay M is energized and in turn energizes the private magnet PM. At the end of the first series of interruptions, relay M resumes its norinal position, thus denergizing the private magnet PM, all as previously described.

The closing of the circuit through inter rupter 1, causes the rotary magnet RM, to

operate the moment the side switches stepinto their second position, which occurs when private magnet PM is denergized.

Following the first operation of the rotary magnet RM, the private magnet PM is again energized a circuit being established from 1, through 70, 71, winding of PM, 2 to 1. Should the first trunk be busy, contact P" tween 17 and 17 now affords a clear pair of wires from thewill be found grounded, as previously described. A circuit is thus established from grounded contact P" through PW, 20, 20 48, 49, this latter contact being closed by the operation of relay S, winding of PM, 2 to 1. In this way the private magnet is sustained as "long as wiper PW passes over busy contacts. The moment, however, a non-grounded contact P is selected, the circuit through the private magnet PM is opened. The private magnet thus becomes deenergized and allows all side switches to step into their third position, thereby open ing circuit of therotary .magnet RM, be-

The circuit of the switch calling station A to the trunk switch Fig. 3, and current flows from earth 1, Fig. 3, through one winding of O, R, RW,'Fig. 1, 19, 19, 66, 67, 51, 69, windingof E, T 5, T telephone set at A, including calling device contact 3, T 4, winding of G, 11, 1Q, VW, V", Fig. 3, the other winding of relay C, 2 to 1. Relay E now operates and holds the switch busy, a circuit being established from earth 1, through 34, 35, winding of L, 2 to 1. As before stated, relay L when energized, opens a release circuit between contacts 25 and 26. The circuit now described will permit of indefinitely extending a call.

The interruptions from station A in operating the distant switches may cause relay E to chatter but not the sluggish relay L. Therefore, the switch circuit will remain unchanged until the permanent opening of the line'circuit at the calling station A. When this occurs, relay E resumes its normal position, thereby allowing relay L to fall back and close the release circuit. The release of the distant trunking switches is eiiected by the deenergizing of relay C, Fig. 3 or its equivalent, which, as before indicated, is also under the direct control of the calling station.

The meter controlling mechanism G in series with the calling line as before stated,

.does not operate when the direction of arm to flow in the opposite direction in the call-.

ing line. The manner in which the direction of current flow is reversed is immaterial as it forms no part of my invention.' Any of the well known methods of current re versing may be employed in this connection.

To restrict local stations to. the making of local calls only, one side of the calling line is connected to conductor T instead of T Fig. 1. Thus when an attempt is made to establish a trunk connection, the calling line circuit is opened between contacts 37 and 60, thereby causing the switch to release substantially as previously described.

Having thus described my invention, what- I claim and desire to secure by United States Letters Patent, is:

1. In a telephone exchange system, a switching device having primary movement and secondary movement, directive controlling means for the primary secondary movements, automatic controlling means for the secondary movement, and means adapted upon a predetermined extension of idlecircuit to disable said automatic controlling means.

3. In a telephone exchange system, a connector switch provided with a plurality of contacts arranged in rows and a movable contact member adapted to be moved into a position opposite any one of the rows and thereafter to be moved into engagement with any contact in said row, directive controlling means for both movements of the movable contact, automatic controlling means for the latter movement normally ineffective, and means automatically actuated upon the movement of the movable contact memberinto a position opposite a predetermined row to disable said directive controlling means and render said automatic con trolling means. effective.

4. In a telephone exchange system, a plurality of subscribers lines having restricted service, a plurality of subscribers lines having unrestricted service, a plurality of trunk lines, switching mechanism operated over said subscribers lines to extend. connection between any two of said subscribers"lines and from any one of said subscribers lines having unrestricted service to a trunk line, but not to extend connection from a subscribers line having restricted service to a trunk line.

5. In atelephone exchange system, a plurality of subscribers lines having restricted service, a plurality of subscribers lines having unrestricted service, a plurality of trunk lines and said called lines,

said impulses over a subscribers line having restrlcted service to disable said switching means, whereby the subscribers lines havingrestricted service are prevented from connection with trunk lines.

6. In ,a' telephone exchange system, a switching device normally in a disconnected position and having primary and secondary movement for making connections, with directive controlling means therefor, and means adapted upon a predetermined extension. of the primary movement to disable said controlling means and restore the switching device to its normally disconnected position.

7. In a telephone exchange system, the combination of a calling line, a plurality of called lines, a plurality of trunk lines, an automatic switch, means to cause said switch to operate and -establish connection between said calling ine and any one ofsaid called lines of a local group by the calling'of two digits only, means to cause said switch to operate and establish connection between said calling line and any one of said trunk lines, and means individual to the switch adapted "to complete the connection of said switch with an idle trunk line by the calling of asingle digit.

8. In a telephone exchange system, the combination of a calling line, a plurality of called lines, a plurality of trunk lines, an automatic switch, means to make said trunk when in use, busy to said switch, means to cause said switchto operate and establish connections between said calling line and any one of said called lines of a local group-on the calling of two digits only, means to cause said switch to operate and establish connections between said calling line andthe first nonbusy trunk line, means for registering the number of completed calls made to subscribers outside of said local group in which the call originates, means to cause the connection of said switch with an idle trunk line 'bythe callingof a single digit, and means of preventing the establishment of av connection betweensaid calling line and any one of said trunk lines.

9. In a telephone exchange system,the combination of an unrestricted calling line, a restricted calling line, a plurality of called lines, a plurality of trunk lines, an automatic switch, a means of causing said switch to operate as a connector and establish con nections between either of said calling lines and any one of said called lines, a means of causing said switch to operate asTa selector and establish connectionsbetwee'n said unare restricted calling line and any one of said trunk lines, and a means of preventing said switch from establishing a connection. between said restricted calling line and any one of said trunk lines.

10. In a telephone exchange system, the combination of an unrestricted calling line, a restrictedcalling line, a plurality of called lines, a plurality of trunk lines, an automatic switch, means to cause said switch to operate as a connector and establish connections between either of .said calling lines and any one of said called lines of a local group by the calling of two digits only, means to cause said switches to operate as a. selector and establish connections between said unrestricted calling line and any one of said trunk lines,means for preventing said switch from establishing a connection between said restricted calling line and any one of said trunk lines, and means to cause the connection of said switch with an idle trunk line by the calling of a single digit.

11. In a telephone exchange system, the combination of a calling line, a. plurality of called lines, a plurality of trunk lines, an automatic switch having primary and secondary movement, means to cause said. switch to operate as a connector and establish connections between said calling line and any one of said called lines of a local group, means to cause said switch to operate as a selector and establish connections between said calling line and any one of said trunk lines, relays adapted when energized to change the circuit of the switch from a circuit adapted to the establishment of said local connections to a circuit adapted to trunk calls to other automatic switches, as when the switch operates as a selector, and means operable in the primary movement of said switch for controlling said relays. 7 12. In atclephone exchange system, the combination of a calling line, a plurality of called lines, a plurality of trunk lines, an automatic switch, means to cause said switch to operate as a connector and establish connections between said calling line and any one of said called. lines of a local group, meansto cause said switch to operate as a selector and establish connections be tween said calling line and any one of said trunk lines, relays adapted when energized to change the circuit of the switch from a circuit adapted to the establishment of said local connections to a circuit adapted to trunk calls to other switches, as when the switch operates as a selector, shaft contact springs adapted to controlsaid relays, means for preventing the establishment of a connection between said calling line and any one of said trunk lines, and a train of relays connected to said calling line branch of said switch and adapted to hold. said switch busy on connections between said calling line and said called lines.

13. lo a telephone exchange system, the combination of a calling line, a plurality of called lines, a plurality of trunk lines, an automatic switch combining the function of a connector and a selector switch and adapted to establish connections between said calling line and any one of said called lines or saidtrunh lines, a calling line branch forming paji t of said switch, a called line branch torming part of said switch, a source of: current for operating said switch, a train of relays connected to said calling line branch of said switch and adapted to hold said switch busy on connections between said calling line and said called lines,

a means of removing said train of relays from connection with said switch on connections between said calling line and said trunk lines and in place thereof, inserting in series with said calling and called line branches of said switch, said calling line, said trunk line and said source of current, and another relay adapted to hold said switch busy, substantially as shown and described.

14. In a telephone exchange system, the combination of a. calling line, a plurality of called lines, a plurality of trunk lines, an automatic switch combining the functions of a connector and a selector switch and adapted to establish connections between said calling line and any of said called lines or said trunk lines, a means at said calling station to cause said switch to establish such connections. calling line branch forming part of said switch, a called line branch forming part of said switch, a source of current for operating said switch, a train of relays connected to said calling line branch of said. switch and controlling the selective powers of said switch as directed by the calling line, and adapted to hold said switch busy on connections between said calling line and said called lines, a means of removing said train of relays from connection with said switch on completed connection between said calling line and said trunk lines and in place thereof, inserting in series with said calling and called line branches of said switch, said calling line, said trunk line and said source of current, and another relay, adapted tohold said switch busy, substantially as shown and described.

15,111 a telephone exchange system, a switching mechanism adapted to act both as a connector and a selector, a trunk circuit for said switching mechanism including condensers, and means operable upon the operation of said switching mechanism as a selector to shunt out said condensers. whereby a circuit for direct current is extended through said trunk and said switch to the next succeeding switch.

r meeeve 16. In a telephone exchange system, autofor the purpose of dn-ectiveiy controlling 10 metic switching mechanism having; primary other switches through said contacts. and secondary movement, directive control- Signed by me at San Francisco, this 17th ling means therefor, and automatic means day of October, 1.911. 5 'operabie upon at predetermined extension of GERALD DEAKIN the primary movement to (115001111661; sand 7 controlling means from said switching mech- Witnesses:

anlsm and extend the connection of said con- PAULINE J. (in-meg,

trolling means to the contacts of said switch, FRANKLIN Cr CAssmY.

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