US1168904A - Extension or party-line telephone. - Google Patents

Description

R. OWENS.

EXTENSION 0R PARTY LINE TELEPHONE.

APPLICATION FILED JULY 5.1906. 7

Patented Jan. 18, 1916.

3 SHEETS-SHEET I.

,Z 2*?78/0/1 I aw I R. OWENS.

EXTENSION OR PARTY LINE TELEPHONE.

' APPLICATION FILED JULY 5, I906. 1,168,904.

Patented Jan. 18, 1916.

3 SHEETSSHEET 2.

null" iifakfzewf R. OWENS.

EXTENSION 0R PARTY LINE TELEPHONE.

APPLICATION FILED JULY 5.1906.

1., 168,904. Patented Jan. 18, 1916.

3 SHEETS-SHEET 3.

rrnio STAWENT orrron.

ROY OWENS, OF CHICAGO, ILLINOIS, KSSIGtNOR, BY MESNE ASSIGNMENTS, TO FIRST TRUST AND SAVINGS BANK, TRUSTEE, OF CHICAGO, ILLINOIS.

EXTENSION OR PARTY-LINE TELEPHONE.

Specification of Letters Patent.

'- Patented J an. 18, 1916.

Application filed July 5, 1906. Serial No. 324,915.

To all whom it may concern Be it known that I, ROY OWENS, a citizen of the United .States of America, and resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Extension or Party-Line Telephones, of which the following is a specification.

My invention relates to telephone systems in general, but more particularly to automatic or semiautomatic telephone systems, and especially to automatic or semi-automatic systems in which several telephones are connected with one and the same line, such arrangements being ordinarily known as extension or party line telephones.

Generally stated, the object of my invention is the provision of an improved extension or party line system having improved means for preventing one subscriber from interfering with the use of the line by an other subscriber 0n the same line, or for precluding the use of one extension telephone in such manner as to interfere with the already established occ'upancy or use of the line by another telephone on the same line.

Special objects of my invention are the provision of improved means whereby each subscriber can release or restore the automatic exchange switches by simply grounding both sides of his line when he is through talking, and whereby, notwithstanding the use of this particular method of releasing, no other telephone or substation on the same line can subsequently be used in such manner as to release any connections already established by some other subscriber over? the same line; the provision of an improved arrangement whereby the use of any tele phone on an extension or party line will temporarily out ofl the releasing grounds from all other telephones on the same line, as well as from the one in use, thereby making it impossible for the switching machinery at the exchange or central station to be accidentally or prematurely released before the subscriber who is in possession of the line is through talking; and the provision of certain details and features of improvement and combinations tending to increase the general eiiiciency and certainty of operation of a telephone system of this particular character.

To the foregoing-and. other useful ends, my invention consists in matters hereinafter set forth and claimed.

In the accompanying drawings Figure I is a diagrammatic representation of an extension orparty line showing the circuits, lockmg-out mechanism, and central office apparatus. Fig. 2 is a similar View of the substation telephone apparatus, together with the locking-out device. Fig. 3 is a detailed view of certain improved parts of the substation. Fig. 4: shows the substation provided with another form of the locking device. Fig. 5 is a diagram showing another method carrying out the idea of my invention, a number of substations being repre-' sented connected to the same line.

Briefly, my invention, as disclosed in Fig.

is provided with a selector A atthe central oifice. Said selector is normally connected with the battery B and is common to the substations C, D, E and F. The central battery B, as shown, preferably has its positive terminal grounded at G, and the substations named are rovided with one common ground G he said ground G is used for sending, calling impulses as well as for releasing. I design the circuits in such a manner that the circuit between the ground G and the releasing apparatus of all the tele-' phones is controlled by the ground relay H. Whenever any one of the subscribers C, D, E or F removes his receiver from the switchhook he energizes the relay E. This relay remains energized as long as the said subscribers receiver is ofi, and as a result the ringer or bell 2, which is also controlled by the relay H, is removed from across the line that leads to the central ofhce, and the ground connection to all the releasing devices is destroyed. Any other subscriber, after the first subscriber has obtained his connection, may come in on the line, but

when he hangs up his receiver, after discovering that the line is busy, he will not release the connection established by the original or first subscriber. The relay H is energized over the subscribers line by the central battery B, but this is not necessary since the local battery B as shown in Fig. 4, may be provided for energizing the ground relay. Also, it may be stated that 1, operates as follows: Each telephone line Sfall-, s nce by" arrangingthe circuitsaas eoihplishedfi, I I I .-"'Fhe'-substation apparatus may be. f r a'n Pressedintermittently, against the ground P s 6 o the-purpose of sending grgund 'impulsesatothe'vertical line'cond-uctor 7 of thesubscribers line. Furthermore, [the said impulse-wheel 3 has a'rotary impulse tooth 8 which, after'the verticalimpulses are sent l p r in, soacts upon the rotaryimpulse finger 9" 3.2 that one ound impulse issent to the rotary "line con uct'or 10; Theswitch-hook11 is provided with theca'm-arms 12, 13. and '14 for controlling certain, circuits to be described. The cam-arm 14 controls the socalled locking cam 15, so vthat' when the switch-hook rises, and before the dial is rotated, the'insulatin'g tip 16 uponthe end of said locking cam is driven to the lnner edge of the angled section on the end of the socalled rground spring '17, -When, the dial "(which is not shown) is pulled down by the .1

calling subscriber the pin 18 upon 'the end of the locking dog 19 raisesthe said locking cam a trifle more and causes the said insulating tip -16'to'fa1l behind the angled sec tion of the spring 17, permitting the latter to make electric contact with the second ground spring 20. Theengagement of the said springs 17 and 20 by the operation described placesthe ground post '6 in connection with the ground G whereby when the subscriber releases the dial, after having pulled it down as described, the vertical impulse teeth 4 will then act first upon the vertical impulse finger 5, and'after that the rotary impulse tooth 8 acts upon the rotary impulse finger 9, as described. The substation is, of course, provided with a transmitter 21 and induction-coil 22, the primary winding 23 of which is, when the switchhook is raised, normally connected in series with said transmitter and with the local battery 24; and the secondary winding 25 is connected in series with the receiver 26 and bridged across the line conductors 7 and 10. When the switch-hook is down the cam-arm 12 separates the springs 29 and 30 and the springs 27 and 28. The cam-arm 14 main tains the springs 17 and 20apart, but when the switch-hook rises the. said springs come into contact, and the springs 31 and 32,

which are normally open, as shown in'dotted lines in Fig' 3, are pressed together. The said springs 31 and 32 may, if desired, ,be

arranged as shown by the full lines in Fig.

3, in which case the cam-arm 12-w0uld con- 7 is not absolutely necessary td use a relay A i aagand the cam-je'fm'iil v theinsulation 6, thus pressin v toward the s ring 32. It will be understood,

11H- Fig.5ii--thi same resultwill beactrolsprings 31 and 3 instead A's the switr'zhshook 11 risesl ot of'. course," t at .the.dotted-1ines.-lin -2Fig. 3- mean to indicate that either 'the full line I springs 31' and 32 or the dotted line springs 31 an 32 may be used. Thegca-m arm 13 is designe to so operate the release springs 33, 34 and: 35 that when the switch-hook descends the said springs'are pressed into con tact, but not when the switch h'o'ok, ascends.

Thefadjustment. of the cam-arms 13 and 14 8Q,"

is su'chthat "as the switch-hook descends the release- springs 33, 34 and'35 are kept in contact-until after the springs 31 and 32 are permitted td-separate. The substation is further provided with a condenser. 36 to maintaini'the line conductors 7 and 10 normally open when the receiver is off of. the hook, for otherwise the said conductors would be connected through the secondary winding 25 and through the receiver-'26. The subscribers signaling device consists of a push-button 37 whichcontrols the spring '38 with respect to the contact-points 39 and 40. It will be noticed that each'gtelephon'e line is provided with only one ringer 2 whichisnormally'connected tllIOll h the condenser 41 across the conductors and 10. This ringer, however, may, as previously stated,

be disconnected from across. the line conductors bythe ground rela'y H, by means of I the springs 42' and 43 which are under the control of the said relay H. 'It will be no- .ticed that the release-spring 35 is connected 1 with the ground G by way of the springs 44- and 45 which are controlled by the ground relay H. The selector A may also, like the substations, be of any desired or'approved character, Preferably'the selector A is of the general class described infPatent No. 815,321, granted March 13', 1906, to Keith, Erickson & Erickson. The line wipers 46 and 47 and the private Wiper 48 are controlledv by the vertical and rotary line relays 49 and 50, respectively, through the mediumo'f the vertical and rotary magnets51 and 52, The release circuits of the selector, as is well 'known, may be controlled through the line relays 49 and 50 or through the 'back-reiease-relay 53 and; the private magnet 54. '-T he said selector when operated may vbe caused to extend the subscribers line conductors 7 and 10 to a connectorswitch I, said connector being of the general class described in Patent No. 815,17 6', granted March 13, 1906, to Keith, Erickson'dz Erick-' In detail the operation of the system is as follows: When the subscriber at substation F desires to use the line he'removes his receiver 26, as shown in Fig. 2, from his switch-hook and proceeds by operating the dial to send in the requisite number of impulses in the proper way for operating the selector A and the connector I toestablish connection with the desired line. As soon 'as the switch-hook goes up the springs 31 and 32 are carried into contact and the ground relay H at once energizes or pulls up. The energizing circuit for the said relay extends from I ground G to the concluctors 57, 58 and 59 to the spring 31, thence through the spring 32 and conductors 60, 61 and 62 to the relay H, thence through the conductor 63 to the rotary line conductor 10 and through the selector ro tary line relay 50 to the battery B. The relay H upon energizing removes the ringer 2 from across the ,line by separating the springs 42 and 43 and destroys the connection'between the substation ground release springs 64,65, 66 and 35 and the ground G After the subscriber at substation F is through talking he may restore the switches at the central office by grounding the vertical and rotary line conductors 7 and 10 simultaneously, as is well known. As the switch-hook descends the release- springs 33, 34 and 35 are pressed into contact and are kept so until after the springs 31 and 3.2 are permitted to separate. As soon as Lthe springs 31 and 32 separate the ground relay H de nergizes and the springs 44 and 45 reengage and restore the connection between ground G and therelease-springs of the substations and, therefore, the ground spring 35. A current then flows from the ground release spring 35 to the release springs 34 and 33, thence by way of the conductors tary line conductors 7 and 10 and through the vertical and rotary line relays 55 and- 56 of the connector I to the battery B. As is well known, the said relays will energize and the switches will be released. If, however, before the subscriber at substation F is ready to release another subscriber comes on the line and, after attempting to make a call, finds the line is busy he (the intruding subscriber) cannot destroy the connection established by the subscriber at substation F by restoring his receiver, since all ground connection is cut off from the release-springs of all the substations. If, however, the subscriber C, for instance, comes on the line just prior to the time when the subscriber at the substation F is ready to hang up his receiver, and the subscriber at substation F hangs up his receiver before the subscriber at substation C does so, the subscriber at substation F cannot then restore the switches byhanging up his receiver, because the ground relay H will be retained energized. This is due to the fact that the springs 69 and 70 at the substation G are now in contact,

68 and 67 to the vertical and ro- J l performing the same function previously performed by'the springs '31 and '32-that i is, providing an energizing circuit for the ground relay H. Of course, therefore, even if the springs 31 and 32 do separate while the release- springs 33, 34 and 35 of the substation F are in contact there will then be no ground circuit established to the line conductors 7 and 10,as previously described. However, when the subscriber at C, hangs up his receiver the switches will be released by him instead. It is clear, of course, that when the relay H is deenergized the ringer 2 is restored across the line conductors; This ringer, together with the ground relay H and associated apparatus, may be mounted upon any suitable frame and retained at any one of the substations, or, if desired, at any other -point.

For some purposesit may be desirable to have each substation provided with a ringer, and it may also be desirable to energize the ground relay H from current provided by a local battery B as shown in Fig. 4. In such case each ringer 2 may be bridged across the vertical and rotary line conductors ,7 and 10 through the condenser 36, as shown. Then again, instead of providing two springs 31 and 32, only the one spring 31 (see Fig. 4) need be provided, the insulation I) removed from the spring 31, and'the rotary. line conductor 10 connected to the switch-hook, as shown; and then when the switch-hook is raised the relay H is energized over a circuit as follows: from battery B through the relay H to the conductor 71, thence to the spring 31 and through the switch-hook 11 to the rotary line conductor 10 and back to battery B The relay H upon energizing separates the springs 44 and 45 and breaks the connection between ground G and all the release-springs of the different substations which are connected with the common lead 74.

When the rin ers 2 are bridged across the line (see Fig. 4% it is not necessary to provide the party line with a line relay,.as in that case the circuits may then be arranged as shown in Fig. 5. The spring 72 is, in that event, bent upward, as shown in Fig. 5, o that the cam 12 may be able to press the springs 72 and 29 together while the release- springs 33, 34 and 35 are still in contact. If no relay is employed the circuits at the substations will be arranged as follows: Referring to Fig. 5, the first substasubstation tion G on theline has the spring 73 con since the ground connection between his ground connection between ground G a when the subscriber at substation C restores (Fig. 1).. to call the substation F at which thence through the springs of the ringing combination of a telephone line,

7 common lead 74. Furthermore, the spring at the substation F upon hearing the signal 29v at the substation F is connected with the s will respond by coming to the phone. Af-. spring '75 of the substation E, and the spring ter the subscribers are through talking they 76w1th the spring 77 of the substation D, will, of course, release in the usual manand in turn t e spring 78 of the substation ner. J

D with the spring 79 of the substation C.

stations removes his receiver, for instan e at the substation F, the springs 72 and 2 will separate and the ground connection between all the ground release- sprin s 64, 65, 66 and 35 and groundGr is thus estroyed.

Patent No. 1,151,544, "ranted on August 24th, 1915, to Talbot Martin. Such a selector is provided with aprivate normal relay 0 that controls a connection between Therefore, if any other subscriber along the ground G and the connector private bankline attempts to'make a call he cannot recontacts. This lease the connection when he restores; his guarding potential at just the instant when i It is necessary, inv order for a substatlon 7 Now, if a subscriber at any one of the s b to call back upon its line, that the selector 1 EA be of the general type described in U. S..

ermits the removal of the switch-hook and presses his release-springs a connector is required to connect with a v 80, 81 and 64 of substation G into contact. It will'be understood that if the subscriber When the relay H is energized by the cen- C attempts to use the line while the subtral battery B good results may be obtained scriber F is on the line, the said subscriber by winding same to seventy-five hundred F will not be able to release by pressing his ohms resistance. Of course, when local batrelease- springs 33, 34 and 35 into contact, teryB as described in Fig. 4, is employed for energizing the relay H, a coil of much ground release-spring 35 and the ground Gr lower resistance may then be substituted for is broken at the substation 0 between the the high wound coil. The battery B may be springs 73 and 79. Subsequently, however, of 50 volts.

From the foregoing it will be seen that I his receiver he presses the release-springs provide each of the several telephones on 80, 81 and 64 into contact, and at the same an extension or party line witha release-cirtime the springs 73 and 79 into contact, cuit for use in grounding both sides of the thereby simultaneously establishing a line to release the switching machinery at d the exchange or central station. In addition, I also provide means forautomatically opening all of said release circuits of the different telephones whenever any telephone is brought into use and the line temporarily the ringer 2 may be located. In that event appropriated for switching or talking or the calling subscriber calls back on his own signaling purposes. In this way the use calling line.

the vertical and rotary line conductors 7 and 10.

It may be deslrablc for the substation C line and bridges the ringer-generator 82 of any telephone precludes the releasing of across the line conductors 10 and 7, by any established connection by the subsepressing his signaling button button 37 is pressed the spring 38 is carried the same line; for when any telephone is onto the ground contact 40 and the vertical used all releasing circuits opened, including line conductor '7 is grounded. Grounding the one allotted to the telephone in use. the vertical line conductor energizes, of WVhat I claim as my invention is course, the ringer-relay 83 of the connector, 1. In a telephone exchange system, the which latter then operates to connect the combination of a telephone line, a plurality ringer-generator across the line, as stated. Current will flow from the ringer-generator through the side switch wiper 84,*shaft wiper 85 and rotary normal conductor 10 telephone, and means for opening all of said (with which the wiper 85 is then in conreleasing circuits when any telephone is tact), to the rotary line conductor 10, thence used. through the relay Hand springs 7 0 and 69, 2. In a telephone exchange system, lthe a plura ity button to the vertical line vertical normal of telephones connected therewith, auto- 7, shaft wiper 86'an d side switch wiper 87 matic switches at the exchange or central back to the generator. The alternating curstation, a ground releasing circuit for each rent from the generator will cause the-'retelephone, each releasing circuit including a lay H to deenergize and energize, causing ground common to all of the telephones, the said relay to rattle. The springs-42 and means for disconnecting the ground and 43 will, of course, be brought into confrom all of said circults when any telephone tact at each operation of the relay H nd 1s used. retained in contact sufiiciently. long to al- 3. In a telephone exchange system, the low the bell 2 to be rung. The subscriber combination ofa telephone line, a plurality 37. When the quentattempted use of another telephone on of telephones connected therewith, auto-- of telephones connected therewith, automatic switches at the exchange or central station, a ground common to all of the telephones, a set of releasing springs for each telephone, one spring in each set being normally connected with the said ground, grounded release circuits controlled by said springs, and means for disconnecting the ground from all of said springs when any telephone is used. c e I 4. In a telephonetexchange system, the combination of a telephone line, a plurality of telephones connected therewith, auto matic switches at the exchange or central station, a ground common to all of the telephones, a set of releasing springs for each telephone, one spring in each set being normally connected with the said ground, a relay common to all of said telephones, provided with contacts through which the said ground is connected with the said releasing springs, as many grounded energizing circuits for said relay as there are telephones,

each energizing circuit controlled by its. allotted telephone, whereby the use of any telephone energizes said relay and cuts oil the ground from all of said releasing springs.

5. In a telephone exchange system, the combination of a telephone line, a plurality of telephones connected therewith, automatic switches at the exchange or central station, a ground releasing circuit for each telephone, and means for opening all of said releasing circuits when any telephone is used, said switches including first-selectors, and the exchange comprising a battery for operating said selectors.

6. In a telephone exchange system, the combination of a telephone line, a plurality of telephones connected therewith, automatic switches at the exchange or central station, a ground releasing circuit for each telephone, each releasing circuit including a ground common to all of the telephones, and means for disconnecting the ground from all of said circuits when any telephone is used, said switches including first-selectors, and the exchange comprising a battery for operating said selectors.

7. In a telephone exchange system, the combination of a telephone line, a plurality of telephones connected therewith, automatic switches at the exchange or central station, a ground common to all of the telephones, a set of releasing springs for each .telephone, one spring in each set being normally connected with the said ground, grounded release circuits controlled by said springs, and means for disconnecting the ground from all of said springs when any telephone is used, said switches including first-selectors, and the exchange comprising a battery for operat'ing said selectors.

8. In a telephone exchange system, the

combination of a telephone line, a plurality oftelephones connected therewith, automatic switches at the exchange or central station, a ground common to all of the telephones, a set of releasi'ngeprings for each telephone, one spring in each set being normally connected with the said ground, a relay common to all of said telephones, provided with contacts through which the said ground is connected with the said releasing springs, as man grounded energizing circuits for said re ay as there are telephones, each energizing circuit controlled by its allotted telephone, whereby the use of any telephone energizes said relay and cuts oil the ground from all of said releasing springs, said switches including first-selectors, and the exchange comprising a battery for operating said selectors. I

9. In apparatus of the character specified, means for establishing a calling connection comprising the combination with a line circuit and a plurality of subscribers station circuits connected in multiple with the line circuit, of aground for releasing any calling connection over, said line, and means common to all of said station circuits and operated from a subscriber station when the circuit is closed through any one of the sta- ,tion circuits for automatically cutting oi the remaining stations from said ground.

10. In apparatus of the character specified, means for establishing a calling connection comprising the combination with a line circuit and a plurality of subscribers station circuits connected in multiple therewith, of a ground for releasing any calling connection over said line, and means com mon to all of said station circuits and operated from a subscriber station for automatically cutting off the remaining stations from said ground.

11. In a telephone system, a line, aplurality of subscribers station circuits permanently connected therewith and a central source of current and means operated thereby and common to all of said station circuits and controlled from a subscribers station whenthe circuit is closed through any one of the station circuits for automatically preventing any remaining subscribers station from interfering with the subscriber al ready in possession of the line.

12. In a telephone system, a line, a plurality of substations permanently connected therewith, and relay mechanism common to all of said substations, located outside of the exchange, and adapted for preventing interference between the different subscribers in the use'of the line.

13. In a telephone system, a line, a plurality of substations permanently connected with said line, and a relay common to all of said substations, located outside of the exchange, and provided with means for auto- 4 circuit.

matically preventing interference between the different subscribers in the use of sa1d line. 14. In a party-line telephone system, party-lines, a ground connection for each subscribers station, and a relay common to all ofthe subscribers stations on a partyline,-located outside of the exchange, and responsive to any subscribers station for automatically breaking the ground connection to the remaining subscribers. stations.

15. In a telephone system, a party-l ne, a calling device-at each substation, switching means at the central station responsive to said de'vice,;a' hook-switch for each substation on the line, a circuit through all the other substations, and means whereby the operation of any hook-switch controls said 16. In a telephone system, a party line, a calling device'ateach substatlon, swltching 'means at the central station .respons1ve to said device, a hook-switch for each substation on the line, a circuit through contacts of all other hook-switches on the line, and means whereby the operation of any hookswitch serves to control said circuit.

17. In a telephone system, a party-line consisting of parallel line conductors, a plurality of substations suitably connected in said line, a plurality of auxiliary line conductors extending between the substations and terminating at the station nearest the exchange or central station, and automatic means for extending connection from said ,partydine.

18. In a telephone system, a party-line consisting of parallel line conductors, a plurality of substations suitably connected with said line conductors, an automatic trunk-selecting switch in which said line terminates;

and means for partially preventing interference between the subscribers in the use of said line, including one or more conductors independent of the line conductors extending through all of said, substations and terminating at the station nearest the exchange or central station.

19. In a telephone system, means includ ing one or more conductors extending through all of the stations on a party-line, but not to the exchange or central station, for partially preventing interference, and automatic means for extending connection from said party-line.

20. In a telephone system, a party-line consisting of parallel line conductors, a plurality of substations suitablyconnected with said line conductors, means for partially preventing interference between the subscribers in the use of said line, including one or more conductors extending through all of said substations and terminating at the station nearest the exchange or central station, and automatic means for extending connection from said party-line.

21. In a telephone system, a party-line consisting of parallel line conductors, a 111- rality of substations 'suitabl connecte in said line, a plurality of auxlliary line conductors extending between the substations and terminating at the station nearestlthe exchange or central station, and automatic mmeans having motion in one plane to select groups and motion in an-intersecting plane to a llne ma selected group for extend- 1ng connection from saidparty-line.

22. In a telephone system, apartydine consisting of parallel line conductors, a plurality of substations suitably connected with said line conductors, means for partially preventing interference between the 'subscribers in the use of said line, including one or more conductors extending through all of said-substations and terminating at the station nearest the exchange or central station, and automatic means having motion in one plane to select groups and motion in an intersectingr-plane to find a line in a selected group for extending connection from said .party-line.

23, In an automatic telephone system, a line, a plurality of telephones on said line,

a ground connection common to said teleground and thereby preclude the other sub scribers from interfering, said relay adapted to be energized and deenergiz ed without affectin the continuity of the line circuit.

25.- he extension or party-line arrangement for automatic telephone exchange systems, including a ground cut-ofl" relay common to the different subscribers on the line, adapted to be energized without opening the line circuit, and automatic switchmg means controlledby said ground connection, substantially as shown and described.

26.*In a telephone exchange system, the combination of a telephone line, a plurality of grounded substations on said line, switchhooks at said substations, telephones on said switch-hooks, and an automatic means for disconnecting all substations from ground by the taking down of any telephone, said,

automatic means including, a ground-controlling relay common to all of said substations. s

27. The combination of a telephone line; a plurality of substations on said line having a common ground connection, a substation rela which is common to all of said substations for controlling the common connection to ground therefrom, and switching means at the central staton responsive to said ground. I 1

28. In a telephone system, a party-line, a substation relay controlling the continuity of said line at a point between the exchange and the first substation, and means for energizing said relay when any subscriber on the line takes down his telephone.

29. In atelephone system, a party-line, a combined line and groundcontrolling relay common to and operable from all of the substations on the part -line, a ground circuit for said relay, said relay controlling a ground connection from a plurality of substations, trunk lines, and an automatic trunk-selecting switch for extending a connection from said line to an idle trunk-line.

30. In a telephone system, the combination of a telephone line, a plurality of substations on said line, a ground connection common to said substations, switch-hooks at said substations, telephones on said switchhooks, and automatic means for disconnecting all substations from said ground by the taking down of any telephone, said automatic means. including a ground-controlling relay common to all said substations.

31. The combination of a telephone line, a plurality of substations on said line having a common ground connection, a substation relay which is common to all of said substations for controlling the common connection to ground therefrom, and switching means at the central station the release of which is responsive to said ground.

32. In a telephone system, a party-line, automatic progressively movable trunking apparatus for said line for calling any desired telephone in the system, a common battery for supplying current for operating and Sigflfidlllg purposes, a circuit from said battery in each party line telephone for controlling progressively movable trunking apparatus, a circuit from said battery in each party line telephone for signaling, and a circuit from said battery for supplying current for releasing purposes to all of said party line telephones, a relay for controlling said last circuit, means for energizing said relay to render said circuit inoperative while the said other circuits are retained operative. Signed by me at Chicago, Cook county, Illinois, this 27th day of June, 1906.

i ROY OWENS.

Witnesses: I

Enw. D. FALES, J 05. T. CARR.

Images