US1114379A - Party-line exchange. - Google Patents

Description

N. E. NORSTROM.

PARTY LINE EIGHANGE.

urucnmx rum) no. 1909.

1,1 14,379. Patented Oct. 20, 19m

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N. B. Noasmom.

PARTY LINE EXCHANGE.

APPLIOATIO! FILED IAY 29. 1909.

1,1 14,379. Patented 00a. 20, 1914.

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N. E. NORSTROM.

PARTY LINE EXGHANGB.

nruonmn mum in 29. 1909.

Patented Oct. 20, 1914.

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N. E. NOB-STROM.

PARTY LINE EXCHANGE.

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1,114,379. Patented 001;.20, 1914 4 SKEETB-BHBET 4 m: will "run an. MLITI11\.IAINIIGM. 0 c.

UNITED STATES PATENT OFFICE.

NILS EMEL NOBSTROM, OF CHICAGO, ILLINOIS, ASSIGNOB TO THE ANDERSON ELECTRIC AND MANUFACTURING COMPANY, OF MoPHERSON, KANSAS, A CORPORATION OF KANSAS.

PARTY-LINE EXCHANGE.

Specification of Letters Patent.

Patented Oct. 20, 1914.

Application filed May 29. 1909. Serial No. 499,250.

To all whom it may concern:

Be it known that I, Nns Exam. Nons'rnoM, a citizen of the United States of America, and aresident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Party- Line Exchanges, of which the following is a specification.

My invention relates to party line tele- Zlphone exchanges, and has for its object improvements in such exchanges, and particularly in the construction and operation of the apparatus located at the several substations.

The apparatus at the central office may be like that shown in my Patent No. 877,727, issued January .28, 1908, or like that shown in my Patent Number 935,049, issued Sept. 28, 190.). In an apparatus of this kind there is a callin device arranged to be mani ulatcd by the operator at the central o co. This calling device may beset in advance for any desired station or stations on a party line and afterward manipulated b turnin a crank or moving a lever. hen sue crank or lever is moved it makes a series of electrical contacts, one for each station on the line, the result of which is to send over the line a corresponding number of impulses. At the instant when an impulse is thus sent for a station for which the device had been previously set, a secondary impulse is sent over the line, the effect of which is to connect the desired station telephonically l to the line. The details of such central 0 cc apparatus do not form a part of the resent application, but they are thus described in brief l'lOCflllHC the impulses so sent control the operation of the apparatus, which will be described.

In the accompanying drawings,-Figure 1 is a front elevation of the switching apparatus located at each sub-station, a portion of the top plate of this apparatus being removed so as to expose the arts beneath; Fig. 2 is a side elevation of *ig. 1; Fi 3 is an enlarged view similar to Fi 1, lit with some additional parts removed: for the purpose of showing details of construction; Fig. 4 is an enlarged section on line 44 of Fig. 1; Fig. 5 is a section on line 5-5 of Fig.

1, showing only a few parts; Fig. 6 is a view showing some of tie parts of Fig. 1

detached, so that they may be seen separated from accompanying parts; Fig. 7 is a detail section through the ratchet wheel, by which the switching mechanism is operated; Fig. 8 is a detail showing the lower end of the armature lever, the pawl thereon and contact operated by the movement of said lever;

Fig. 9 is a. detail showing the attachment of the permanent magnet; Fig. 10 is a transverse section of the signal lever shown in the upper front part of Fig. 1; and Fig. 11 is a diagram of two substations on a party line, the jack for which is shown at the left and is assumed to be in the central oflice to which the central oiiice apparatus is connected by means of an ordinary cord and plug.

In the said drawings, 40 is a sheet metal base, on the upper edge of which is supported an electromagnet M provided with an armature M Secured to-the centrally pivoted armature M is an armature lever 41 having a pawl 42. at its lower extremity. This pawl engages the ratchet wheel 43 mounted on a central spindle 44 and serves to rotate said wheel when the armature lever is pushed toward the left, as shown in Figs. 1 and 3. When the armature lever is moved to the right the bent portion thereof thrusting against the fixed post 45 raises the pawl 42 out of the wheel 43 and permits said wheel to be returned to its normal end position by means of a spring 46 which surrounds the spindle 44. On the bottom face of the wheel 43 is a pin 47 which strikes against an adjustable pin 48 when the wheel 43 reaches its normal position on such backward movement. The normal position of the wheel 43 is thus determined by contact between the pin 47 and the stop 48, and this stop is adjusted so as to leave a slight clearance between the pawl 42 and the projection 49 on the wheel 43. The reason for this is that, while the spring 46 for returning the wheel 43 to normal position is intedcd to be as light as possible so as to reduce the power required to operate the magnet M and consequently the amount of current that must be sent over a long line to operate a number of such magnets, the spring 15 might be still lighter, with the result that if the projection 49 is pressed a ainst pawl 42 when in normal position the electrical connection between 15 and 16 would be open when it should be closed. The adjustable character of the stop 48 permits the clearance between i2 and 49 to be adjusted to any degree of fineness.

The wheel 43 maybe secured to the spindle -14 in any convenient manner, but preferably is pressed thereon. Between the wheel 43 and a shoulder on a spindle 14, as shown in Fig. 7, is a spring piece 50, having a piece of insulation 51 on the outside end. The piece 50 is in the form of a fork, as shown in Fig. 3, and consequently may he slipped out of position, but is normally held in position by a considerable friction. It may also be rotated by hand and set at any given position on the wheel 43 with respect to the projection 49 thereon.

Secured at a convenient place on the frame 10 are two insulated contact s )rings 26 and 27, one of which has its end in the path of the insulated piece 51. The springs .26 and 27 are normally out of contact with each other, but when the insulated portion strikes the bent end of the sprin 2G by reason of the rotation of the wheel 43, the said spring 26 is pushed into electrical connection with the sprin 27. This electrical connection exists only during one step of the ratchet wheel 43. At all steps prior to this contact or thereafter the electrical connections between 26 and 27 are open. At the different stations on the party line the piece 50 is adjusted so that the insulated end 51 will be a different distance from the projection 49. For example, in station No. 1 the insulated portion 51 will strike the pin 26 when the ratchet wheel has moved one step. At station No. 2 the insulated portion will strike the pin when the ratchet wheel has moved two steps, and so on. As will be hereinafter described, the ratchet wheels of stations move forward simultaneously with the result that the electrical connection between 26 and 27 are made at the diil'erent stations successively and correspond to the impulses sent out from the central ollice by the operator manipulatin an instrument such as previously described.

A portion of the spindle 44 is cut away on one side, as shown at 52, in Fi s. 3 and 7. At a convenient place on the rame are supported three springs 3, 4 and 21. The middle spring 3 has a piece of insulation on the end which rests in this cut-out place 52, when the ratchet wheel is in its normal position. In this condition the spring 3 engages the contact sprin 4, but when the ratchet wheel 43 and its spindle 44 are turned, the cut-away portion 52 acts as a cam on the end of spring 3 and pushes it away from the contact spring 4 in connection with the contact spring 21. \Vhcn the apparatus returns to normal position the connections are restored to the position shown in Fig. 3. On the armature lever 41, as shown in Fig. 8, is a pin 53, which lies between pieces of insulation secured to springs 15 and 17. In normal position the springs 15 and 17 make electrical connection with the central portion 16, but when the armature lever 41 is moved in either direction it presses against the insulation on the end of the springs 15 and 17 according to the direction of movement and breaks the connection between the moved spring and the fixed part 16. The construction of these is shown in Figs. 5 and 8 in more detail than in the other fi ures. On the fixed part 16 is a pin 54 on which is pivoted a signaling lever 55, one portion of which is dark or colored and the other portion of which is light, as shown in Fig. 1. The lower end of the signaling lever 55 ends in a fork which embraces the movable pin 53. The view, as shown in Fig. 1, shows the switching apparatus at normal )osition with the light part of the signaling lever at the central part of the apparatus. This apparatus is presumed to be in a box with a peep-hole opposite this central part so it may be seen whether the line is in use or not. When we consider the apparatus in the position shown in Fi 1, if the armature lever 41 moves to the left to advance the ratchet wheel the pin will strike one tine of the fork on the signaling lever 55 and throw it to the reverse position with the dark part at the upper end of the center of the apparatus. If the lever were at the other position, the movement of the pin 53 to the right would strike the. other time of the fork and throw the lever to the position shown in Fig. 1. In the upper part of this lever 55 is a slot 56, in which is a sliding weight 57. Assuming the apparatus in the position shown in Fig. 1, if a movement 0 the armature lever to the left throws the upper end of the signaling lever to the right, the sudden stopping of this lever The weight 57 i will result as a rebound. very loosely carried on the slot 50 and continues to move in the said slot after the lever itself has stopped and commenced to re bound. The movement of this weight 57 against the rebound or lever itself will prevent the RibOllTKl of this signaling lever amounting to enough to affect the apparatus. In other words, this sliding weight in this piece very perceptibly lessens the rebound resulting from the sudden stopping of the signaling lever when thrown to either the right or the left. A similar apparatus is shown at 58 in the ratchet wheel 43 for preventing rebound of that wheel when returning to normal position.

Located on the lower portion of the base 40 is a magnet 25) provided with an armature 59, the end of which engages an inclined face 60 on a pivoted lfifll iil mounted upon a pin 62 in the base -10. The other end of the pivoted lever (31 lies adjacent to the pin 47 carried by the ratchet wheel 43. When the magnet 29 is operated to attract this armature 59, the spring surrounding the post 62 causes the pivot lever 61 to catch and hold the said lever 55 in an attracted position, but in a position considerably less than its extreme movement. The catch point on the lever 61 is shown at 63, and the other end of the armature lever lies adjacent to a series of contact springs 2324 32-33 and 35. \Vhen the armature lever 59 is in its normal position these various springs make electrical connections, as shown in the drawings. \Vhen the armature lever is moved enough to be caught by the catch 63, these connections are shifted, as will be hereinafter described. The end which moves these contact springs is provided with a clapper 74.- adapted to engage a bell 75 whenever the armature 59 is actuated.

Fig. 6 shows the apparatus in a normal )osition. An impulse flowing through the magnet 29 will attract the armature so that it may be caught by the lever 61 and will at the same time cause the clapper 74 to strike the bell 75. After this takes place the magnet may be operated a number of times resulting in ringing the bell 75, but without changing the electrical connections due to such ringin The connection made between 61 and 59 is a connection that is made after the ratchet wheel 43 has been moved from its 1 normal position. Assuming the wheel to be so advanced and the armature lever 59 to be cau ht and held by the lever 61, the return of tTie wheel 43 to its normal position will cause its pin 47 to strike against the tail end pivoted lever 61 and disengage the catch 63 from the armature lever 59. The contact springs before mentioned then act to push the armature lever 59 outward against the inclined face 60. The in 47 'trikes the lever 61 just before it stri es the stop pin 48, and the momentum of the wheel 43, in returning to its normal position is snilicient to move the lever 61 so that when the armature lever 59 engages the inclined face 60, such arrangement will hold the lever 61 clear of the pin 47 with the result that the spring 46, which returns the ratchet wheel 43 to normal position need not be powerful enough to overcome the spring on the pin 62. which moves the lever 61. The general object to be obtained by this is to make the tension of the spring 46 as light as possible with the result that very little force is required of the magnet M to advance the ratchet wheel.

livoted at a convenient place is a holding pawl 64, and projecting tail piece 65 on the extreme end of the armature lever 41 engages this holding pawl in such a way that when the armature lever is moved to the right to release the pawl 42 from the ratchet wheel 43 this tail piece 65 lifts-the holding pawl 64: at the same time, thus leaving the 'ratchet wheel 43 entirely free to return to its normal position. A very light spring 66 serves to hold the holding pawl 64 in engagement with the wheel 43 when not pushed outward by the tail piece 65.

Secured to the upturned lip of the base 40 is a. permanent magnet 67, see Figs. 2 and 9, the upper end of which is bent around through 180 degrees so that the end face of this permanent magnet is directly above the armature h 1 and in line with the cores of the electromagnet M. Bent around in this way the lilies of,force are directed to the armature in a more efficient manner than when the end of the magnet simply projects over the armature in the ordinary way. The lower portion of the permanent magnet 67 is adjustable by means of a screw 68 operating in a slot 69 in a magnet 67. By means of these parts the magnet 67 may be ad justed to or from the armature M with any degree of fineness that may be desired, with the result that the armature is polarized in a more efficient manner.

Referring now to Fig. 11, it will be assumed that the subscriber at station, marked No. 1, desires to talk to the subscriber at station No. 2, or with any other subscriber on the line, as may be desired. The opera tion of effecting connection between two subscribers on the same line is as follows: The calling subscriber turns his generator G when the current flows 12-3-4-5-6 7-89-1011121314.l516- 17-18-G. This operates the drop 10 at the central ofiice and calls the operator there, who inserts a plug in the jack J and inquires what, station is wanted. The talking circuit, as far as the local station is concerned, is as follows: induction coil K-19- receiver R--23456-8central offiec a paratus-l213l415l6-l7- 18- 20K.

The subscriber having informed the operator at the central ofiice that he desires to talk to the subscriber at station No. 2, the operator will then set her apparatus for stations 1 and 2 and turn the crank or move the lever to send as many impulses over the party line 612 as there are subscribers on the line, or a few more impulses than there are such subscribers. At the first impulse, each apparatus movcs forward one step. As previously described, the connections .26 and 27 will be closed at this time for station No. 1. At the second step the similar contacts will be closed at station No. 2. The apparatus having been set for these stations, there will be a secondary impulse accompanying the primary impulse from the central oilice. The primary impulses flow over the party line 6-12 through the magnets M, which are bridged on the line (3-l as shown in Fig. 11. The secondary inipulse for these stations is an impulse which connects one of the lines to ground through a battery, the current flowing in this case from the central office through lines 12 1326272829-ground back to the central oliice. This is an impulse through the magnet 29 which operates said magnet to attract its armature to be caught hold of by the catch 63. This shifts the contact springs, as previously described, for station No. 1. In the same manner the contact springs are shifted for station No. 2, but they are not shifted for any other station on the line because similar im )ulses are not sent from the central ofiice or selection of 5 any station other than the two it is desired to place in telephonic connection. The advance of the switching mechanism breaks the connection between the contact springs 3 and 4, as )reviously described, with the re sult that the previously described talking and ringing circuits are broken at this point. When this connection is broken at this point for a station in which the magnet 29 has not been operated, the receiver R for such station is shunted by a circuit as follows: R 2. -21-2-223-24-25-KR. For the stations, however, in which the magnet 29 has been operated so as to break the connection between 23 and 24, this shunt is broken 30 and this exists for-stations No. 1 and No. 2, which we resume are the ones selected. In general e ect we may therefore say that the operation of the switching mechanism for a. given station operates to shunt the receiver thereof, and thus cut it off from telephonic connection with a party line, after which the operation of the magnet 29, in case such magnet is operated, results in a ain connecting the receiver telephonicall y to the line. If, however, the magnet 29 is not operated the receiver remains shunted with the result that the subscriber at that station is cut off from telephonic connection with the line.

The impulse which is described through magnet 29 causes a signal stroke on the bell at the station which is selected. The calling device used usually has the latter and of its movement so arranged that it will send a series of impulses through the magnet which has been previously operated. This is accomplished by reason of the connections 32 and 33. which are closed by the first operation of the magnet and serves as connection 65 for magnet 29 as follows: from a central oflice over line 12-13-l4-15-1617- 18H313233--34-29gr0und back to the central office. It will be observed that the central oliice sending impulses to line 12 and ground would not reach its magnet 29 unless the connections 32 and 33 had previously been closed in the manner before described. These connections, therefore, serve as means for automatically signaling the called subscribers with a portion of the normal movement of the calling device used for selecting stations. Such calling operation, however, may be a separate key which would send impulses over the circuit just described. '10

The talking circuit between stations 1 and 2 as so far described would be as follows: beginning at K of station No. 119-R-2- 3212223' 5-3645-6 to 5 of station No. 2363523-22213-2R 19K20- H --1817-1615-1sl-13 12-back to 13 of station No. 1-1415 16-171S-H20-K. \Vhen through talking the subscriber rings off, when the circuit closes as follows: G12-3--21-- 22-23353656clearing out drop at central oflice12131415--1G-17 l8-G. The operator then sends the impulse over the party line in the opposite direction from those sent to operate the magnets M to advance the switching mechanism. This impulse in the opposite direction moves the armature lever 41 to the left and releases the various switching mechanisms, as previously described so that their springs 46 may 9 return them to their normal position. At stations No. l and No. 2 which have operated their magnets 29 and have their levers 61 moved so as to catch-and hold the armatnres 59, the ends of such levers 61 will be advanced far enough so that they will be struck a-blow by the pin 47 on the ratchetwheel 43 just as it is arriving at its normal position and just before it comes into contact with the stop pin 48. This blow releases the catch levers (S1 for these two stations and permits the armatures 59 to flow back to their normal position under the action of the springs 23 and 33, which press against the other end of the armature lever and which were shifted in their connection by the attraction of said armature by the, magnet 29. Connected to one of the branches which go to each station is an emergency key 70 which enables a subscriber to call up the central office even when the line is in use by other parties. F or example, the subscriber who needs to call the central oilice in a case of emergency presses this key 70 and turns his generator, when a current flows as follows: G127(l5fi8ccntral ollice apparatus back to 12l3 of the signaling station141516-1 7-13-( There of course, a branch of this circuit going through his own magnet M and also through the corrcspomling magnets of the other stations. The current in the generator, however, does not operate thcsc magnets, or at least operates them to only a minute extent because this circuit passes through the central fixed part 16 and the contract springs 15, 17 on each side of it. The instant the magnet begins to move, the armature 11 thereof moves either spring 15 or spring 17 from its normal position in contact with the fixed part 16, with the result that this impulse through, such magnets is brokenbefore it accomplishes any result of moving the switching mechanism.

The holding pawl 64- is made of a pieceof spring metal bent back upon itself, as shown in Figs. 1 and 3, and the two branches of which are connected together by a screw 80 which is under tension by the spring action of the metal. Tightenin the screw 80 tends to shorten the pawl by drawing its holding end nearer to its pivot. Slacking u on the screw produces the opposite effect 0 lengthcnin g the pawl. By thus adjusting the holding pawl Get the teeth of the wheel 43 may be held during operation at any desired relationship to the driving pawl 42.

What I claim is:

1. The combination with a magnet, an armature lever moved thereby, and springs for normally holding said lever in a mid-position, of a ratchet wheel arranged to be advanced from normal position by a movement of said lever in one direction and to be released by a similar movement in the other direction, a spring for returning said wheel to normal position when so released, a catch arranged to be released by a blow delivered by said wheel as it arrives at its normal position, said catch when not in operation being normally held so as not to be touched by said wheel.

2. The combination with a magnet, an armature lever moved thereby, and sprin s for normally holding said ever in mi position, of a ratchet arranged to be advanced when said lever is moved in one direction and to be released when movedin the other direction, a spring for returning said wheel to normal position when so released, a catch arranged to be struck by said wheel to release the same as the wheel is arriving at normal position, and an adjustable stop arresting said wheel at its normal position.

3. The combination with a ratchet wheel, means for advancing it, and a spring for returning it to normal position when released, of an armature, a spring actuated catch for holding said armature in an attracted position, aprojection carried by said wheel and arranged to strike and" release said catch when said wheel returnstowhich said normal position, and means by 1 said projeccatch is icld out of contact wit tion after said catch isreleased.

4. The combination with a ratchet wheel, means for advancing it, and a spring for returning itto normal position when released, of an arm arranged to operate electrical connections when moved fromits normal position, a'catch for holding it, in such moved position, means 'forieleasing said catch upon the return of said wheel to its normal position, and means by which said catch in its released position is held clear from the means used for releasing it.

5. The combination with a ratchet wheel, means for advancing it, and a spring for returning to and beyond normal position when released, of a series of contact devices, an arm arranged to actuate said devices when moved from its normal position, a catch for holding said arm in its normal position, means carried by said wheel for releasing said catch so that the arm held thereby may return to its normal position, and means by which said arm in its released position is held clear from the means for releasin 1t 6. 'l he combination with a ratchet wheel. means for advancing it ste by step, and contact devices adapted to e temporarilv actuated at some particular step of such advance movement, of a piece carried by said wheel for engaging and actuating said contact devices, said piece being ad ustable by hand on said wheel and being held at any desired position by spring tension.

7. The combination with a spindle and ratchet wheel secured together, means for advancing said wheel step by step, and contact devices adapted to be actuated at some particular step of such advance. of a removable spring piece held by compression between said wheel and a shoulder on said spindle, said spring piece being adjustable by hand so that the projecting end thereof may be located at any desired position on said wheel with respect to'some fixed part thereof, and said projecting end being. arranged to engage and actuate said contact devices when moved past them by the advance of said wheel.

'8. The combination with a spindle, a ratchet wheel secured thereto, means for advancing said wheel, and contact devices actuated by such advance, of a fork-shaped piece of spring metal adapted to be inserted etween said wheel, and a shoulder on said spindle and to'be held in any desired positlon by friction, said fork-shaped piece havmg a projecting end for engaging said contact devices.

9. In the substation apparatus of a party line exchange, the combination with a rece ver normally in telephonic connection with the party line through a contact closable' by the switch hook, of a switching mechanism at the same station with the receiver and adapted upon advance to shunt the receiver, a magnet adapted to break such shunt andto establish a new telephonic connection for the receiver when actuated, said magnet also being adapted to operate a signal receiver when. actuated, and means for holding the connections made by the actuaee i\'er normally in telephonic connection with the party line through a contact closable by the switch hook, and a signaling ma net normally not in operative connection wit li the line, vof a switching mechanism adapted upon advance to shunt the receiver so as to destroy its telephonic connectionto ,the lineiand also to temporarily connect said magnet between "round and one branch of the line, electrica connections for breaking such shunt and establishing new telephonic connections for the receiver and also for establishing a new connection,forsaidmagnet, means by which anpperation of said magnet during its temporary connection operates said electrical connections, a catch for holding such electrical connections in operated condition,'means by which said magnet may operate for signalim without interfering wit 1 the connections held by said catch, means by which a return of the switching mechanism .to its normal position will release said catch so as to permit the connections held thereby to also return to their normal position, and means for holding the released catch away from the means for releasing it.

11. Ina arty line exchange, the combination with t 1e line limbs, a series of electrically operated switching mechanism, each having its operating magnet in permanent bridge of said line limbs, and springs for returning the switchin mechanisms to nor- 1 lIliLlPOSltlOIl when reeased after advance movement, said springs each being as hght' as will return the swltching mechanisms at electrically operated mechanism for governing the telephonic connection of the receiver to the line, and means for releasing the electrically o erated mechanism by the blow l delivered y he switching mechanism when being stopped at thetermmat on of its re.- turn movement.

and a telephone receiver, of a connective mechanism for governing the telephonic connection of the receiver to the line, a selective mechanism operated by impulses sent over the line and serving to govern the operation of the connective mechanism, means by which the connective mechanism is held in an operated position after operation, a spring for return ng the selective mechanism to normal posltion when released, and means for releasin the connective mechanism by the blow cfizlivered by the selective m a i h n amen memeh 1 stepp d ata aal Beaten,

J anew l3. Substation apparatus for party telephone-lines including switching mechanism, a detent for holding the switching mechanism in the osition to which it has been actuated, an electro-magnetic mechanism including a motor magnet and a signal-receiver for the substation, and serving to operate the said switching mechanism, to permit the detent to engage the same and for releasin the detent from connection with the said switching mechanism.

14. Substation apparatus for party telehone-lines, switchln mechanism, a detent or holding the switching mechanism in the position to which it has been actuated, and electro-magnetic mechanism for releasing the detent from connection with the switching mechanism, including a motor magnet and a signal receiver, which receiver serves to 0 erate the switching mechanism, to permit the detent to engage the same.

15. The combination with a selecting device, and a signal receiver at a local station of a party line exchange, of connections for operating the selecting device so as to connect the signal receiver to the line and for operatin the signal receiver when so connected, a telephonic connection for the station closed by the signal receiver, and means controlled through the selecting device for breaking such telephonic connection.

16. The combination with a central oliice, a series of local stations, and a party line, of a paratus at each station consisting of a telep one receiver normally in operative relationship with the line through a contact closable by the switch hook, a signal receiver normally out of operative connection with the line, a selective mechanism permanently in operative relationship with .a moderate speed, of a tele hone receiver,;

said line and so arranged that upon being op- 1 erated it will first break the operative relationship between the telephone receiver and the l neand will subsequently place the signal receiver in operatlve connection, and means j by Which an operation of the signal receiver Wlll restore the operatlve relationship between the telephone receiver and the line. 12. The comblnat on with a party line 17. The combination with a central ollice, a series of local stations, and a party line, of a telephone receiver at each station normally in operative relationship with said line through a contact closable by the switch hook, a signal receiver at each station normally disconnected from the line, selective devices at each station simultaneously operated from the central ofiice, means by which anon operating said selective devices said to ephone recelvers will have their operative relationship with the line simultaneously interrupted, means by which further operation ,of the selective devices will conne t the signal receiver successively to the line so that they may be operated from the central oiiice, and means by which upon operating a signal receiver to call the subscriber at a station such operation will serve to reestablish the operative relationship between the associated telephone receiver and the line.

18. The combination with a telephone line, of a telephone receiver normally capable of telephonic connection with the line, switching apparatus adapted to restore telephonic capability to said receiver when interrupted, a signal receiver arranged to o erate the switching apparatus but normal y disconnected from the line, and a selective mechanism connected to the line and arranged to interrupt the telephonic capability of the telephone receiver and to connect the signal receiver to the line so as to bring I about a. restoration of the telephonic capability of the telephone receiver.

19. The combination with a party line, of a series of telephone receivers each normally capable of telephonic connection with the line, selective mechanism for each receiver and connected to the line so that all mechanisms are simultaneously operated, a signal receiver for each telephone, means by which the operation of the selective mechanisms serves to interrupt the telephonic capabilities of their respective telephones, contact devices operated by the selective mechanisms and arranged to complete connections successively to the signal receivers of different telephones so that the said signal receivers may be operated, and means by which the operation of any signal receiver serves to restore the telephonic capabilities of its respective telephone.

20. The combination with a arty line, a telephone receiver arranged to e placed in telephonic relationship with the line, a signal receiver, a contact device controlling the telephonic relationship of the telephone receiver with the line, means for operating the contact device by an operation of the signal receiver, and a catch for holding the contact device in its normal position.

21. The combination with a party line, of a signal receiver provided with devices for establishing its own connection with the line, and connections through which an impulse may be sent for causing a preliminary operation of said signal receiver so as to establish such connection.

22. The combination with a party line, of a series of signal receivers each of which is provided with devices for establishing its own connection with the line, and connections through which an impulse may be sent for causing a preliminary operation of any one of said signal receivers so as to establish such a connection therefor.

23. The combination with a central oilice, a series of local stations, and a party line, of a signal receiver at each station, contact devices by which each signal receiver closes its connection with the line, selective apparatus at each station and controlled from the central oflice, each selective apparatus being provided with means for closing a preliminary connection between the line and its as sociated signal receiver, and means controlled from the central ofiice for sending an impulse through such preliminary conncction so as to cause the signal receiver to operate its contact devices.

Signed at Chicago, Ill. this 27th day of May, 1909.

NILS EMEL NORSTROM.

Witnesses:

C. L. REDFIELD, CARRIE E. JORDAN.

Copies of this patent may be obtained for live cents each, by addressing the Commissioner or Eatents,

Washington, D. 0.

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