US941743A

US941743A - Telephone-line selective switch device.

Info

Publication number: US941743A
Application number: US35853407A
Authority: US
Inventors: John H Swanson
Original assignee: T F ROBINSON
Current assignee: T F ROBINSON
Priority date: 1907-02-21
Filing date: 1907-02-21
Publication date: 1909-11-30
Anticipated expiration: 1926-11-30

Description

. J'. H. swANsoN.

v TELEPHONE LINE SELEGTIVE SWITCH DEVICE.

- i f rumanos num 1111.21, 1am. v v

,743, Patented NOV. 30, 1909. `f u I '7 v zsnn'rs-sxnnfr 1.

5 I- e /I I.

g 5a 55 bf; 5.2.

mms-3;.

J. H. SWANSON. mmnon: LINE sBLEcTrvr: SWITCH DEVICE.

LPELIOATIOI FILED FERRI. 1967..

Patented Nov. 30. 1909.

2 SHEETS-SHEET 2;V

UNITED sTATEs PATENT oEFieE.

I'OHIN' H. SWANSON,

F vBLDIN, WISCONSIN, ASSIGNOB 0F ONE-FOUTH'TO F.

ROBINSON, 0F ST. PAUL, MINNESOTA.

l TELEPHONE-LINE SELECTIVE SWITCH DEVICE.

.. To all whom 'it may concern:

Be it known that I, JOHN H. Swanson, of Baldwin, St. Croix county, W'isconsin, have invented certain new and useful Im,- proveniente in' Telephone-Line Selective Switch Devices, of which the following is a specification.

'In telephone systems a line, which I will` designate asy the mainline, is connected to another line entendingnfrom the termination of the main line, the second line, for convenience being designated as the sub-station line. To. illustrate, 4connected to and proceeding from a central telephone st-ation is a line consisting of two metallic conductors having atk the .central station the usual means for receiving and answering telephone' signals. The` main telephone line proceeds to a distant point from the central station an .hasalong its route'a plurality of telephone stations coiinectedgto it in what is known as a bridged manner.v lAt the ter-y 1- v ininationof the iiiainv telephone v line my invention is located, vvand yconnected to and proceeding from the terminal of `the main line is a second line independent of the i main line, consisting 0f two metallic condnctors extending into an outlying territory. Sub-stations may be connected to these conductors iii the usual way. It isassumed that the sub-'stationn line is to be under the control of the central station as though vdirectly connected to it li'y metallic conductors independent of the main line conductors. Heretofore 'it has been necessary to maintain at the sub-station or main line terminal an operator for the purpose of connecting or ,disconnecting the main telephone line and the sub-station line when telephone stations upon the main line desired rto coinmunicate with stations upon the sub-station line.

The object of n'iyinvention isto provide means whereby the expense of such an operator at the sub-,station can be avoided and the supervision and control of the sub-station line be at all times under the central station operator, thereby providing for a` erfeet checking system where toll is charged between main line telephone stations andy sub-line stations.

The inventionlis particularly adapted for rural or party farm telephone lines .where it is used in developing outlying territory Specication of Letters Patent. ,Patented NV. 30, 1909. Application tiled February `21, 1907. Serial No.' 358,534.

wit-hout the necessity. of extending lines from such territory into the central station. It is understood that in rural telephone systems the party line is most generally used and that such systems a're limited to the number of telephone stations capable of snccessful operation on one .circuit and when` the lterritory adjoining the central station fully developed, that is, when all possible telephone. users in the. territory adjoining the central station have beensupplied with telephones, the territory outlying beyond the radius of the central station territoryV can only be supplied with telephone service'by the extension of other linesfronithe central station through the already developed territory contiguous to or adjoining the central station. supplying telephone service to aterritory at'a distance from the central station much greater than to supply the territoryadjoining a central, telephone station.

By the use of my .invention the expense of extending lines through an already developed territory is eliminated, the substation line being connected to the main line and the central station operator having coniinunicatioii at all times with the sub-station lilies without the necessity of'an operator at the main line terminal.

The, invention consists generally in various constructions and combinations, all as hereinafter described and particularly pointed outin vthe claims.

Consequently the expense of.

Iii the accompanying drawings, forming part of this specification, Figure li-s a diagrammatic view ofv a telephone system enilbodying my invention.

Fig. i). is a front view ot the switch device at, the sub-station.

Fig. 3 is a side view ofthe same. Fig. 4 is a sectional viewvertically between the cores of the magnet. v

For lconvenience in manufacturing, I utilize the

electromagnets

3 and 3 of an ordinary polarized telephone bell having the usual windings which I will hereinafter designate asV the primary windings,l and -outer`

windings

3 and 3* of a heavier wire hereinafter referred to as the secondary wind ings. y

4 is a softiron armature, which I will designate for convenience of description as los the primary armature, having a rod 4f with its end bent at an angle to theinain portion 'y i and carrying an insulating post 5 having a slot to receive a contact spring 6. The armature 4 is pivoted at 7 and swings back and forth carrying with it the rod 4 and moving the contact spring 6 toward

springs

8 or 9. A permanent magnet IOVcharges the soft iron armature 4-with a golarit of 4magnetism opposite to itself an there y causes this armature to be alternatel attracted and repelled by magnetism pro uced in the cores of the

electromagnets

3 and 3 when a current of electricity is passed through them. The armature 4 is dependent for its direction of movement upon theiolarity of magnetism in the magnets 3 an 3 larity, a positive polarity in electroinagnet 3 would repel the armature 4 and a negative polarity in electroniagnet 3 would attract the armature 4. YWhen the polarity in the electromagnets is reversed, a reverse action will take place in the armature 4' and it will move in the opposite direction. Thus it will be understood the -rod 4 controlling.

contact spring 6 can be'moved in either' direction toward

springs

8 or 9 by the appli cation of electricity to the electromagnets' and 3.

`12 is a second armature, designated for v convenience the'secondary armature, extend# ing across tli'e two nets 3- and .3.

11 are ole piecescoiinected with the magnets 3- 3 to conduct the magnetic iiux at poles of the electromagan angle with thecores and attract the armai armature A12 is hel A:se

. l battery circuit Bat the switch device i attract the steel armature 12.

ture 12. This armature is of steel or hardened Airon and adapted to retain an magnetic charge when attracted by the po e pieces 11, as usual with magnets of this kind. The

pole' pieces b 'a support 13 which is pivoted at 14 on a p ate A15. Contact springs 16, 17, 18, 19,- 20 and 21 are mounted in insulating blocks 22on the plate v15. The 'support'13 has arms .23 arranged "tocontact with iiisulating blocks 24 on the springs -17. and 20,

. whereby the said springswill be moved when the support is oscillated. yThe lsprings 17 and 20 have

contact points

25 and 26 and the tension of the springs normally holds these points in engegement-with the springs 18 and 1.9J and t e armature 12away from the polepieoes 11. When the electromagnets 3 and' are energized they attract the arma- 12am] lmove springs 17 and 20 into ent with's rings 1.6 and 21 and'hold e armature an springs in that position. 27, A28 and 29 1n Iig. 1, represent the amaturesof an induction coil having four

inde endent windings

30, 31, 32 and 33.' A

furnishes a current of sufficient strength to lThe local batterygin circuit B eonnect'ed withrespect. to itself, that is, if the .permanent magnet; maintains in ,the armature 4 a positive po-` directly in front of the with .3 and 3" and contact springs o, o and 9, supplies a current of sufficient strength to attract the steel armature 12 to the pole pieces 11 and thereby gives the sai'd armature an initial charge of ina ietisni when the battery circuit is closed. rIsl-ie purpose of the attractionr of theisteel armature to the pole pieces 11 is to bend contact 'springs 17 and 20 and thereby break contact' with

springs

18 and 19 and open the circuit between lines R and Sand conductors X and Z, and to inake contact between s rings 17 and 16 and 2O and.21 and close t e circuit betweenlines R and S, and M and L. The steel armature upon being attracted to the pole pieces closes the ma etic field in electronia ets 3 'and 3 an thereby deprives the primary armature 4 of magnetic inuence, which through tlieaction of the contact spring 6 is restored to a neutral position with respect to the electroinanets,y and oiens the circuit through the atteiy ll.

he initial charge ofmagnetism in the steel armature causes it to adhere to the pole vpieces and maintain contact between

springs

17 and 16 and 20 and 21 after the battery H circuit has been broken. Nor is its electrical equilibrium disturbed. When a discoiuiection of any' connected line is desired, the method used in my device is an exti'eiiiely simple one, employing as I do :i well known principle; that an alternating current of electricity when present in an electiomagiiet coil will de-magnetize a permanent muguet within. its field of magnetic flux.

In my system ofoperating the said switch device, I use an alternating current of electricity, such as is ordinarily used for the purpose of rin' ing polarized telephonev bells in telephony. ythis means, I simplify the operation of my apparatus, as no s cial devices are necessary at the centra station, other than are found in any telephone celitral station.

- The secondary wiiidin s, or the outer coils 3". and 3b are of a size o wire.proportionate to the exciting current used, ai`i d 'iii ordinary practice, I find that iicoil of about 10 ohlns resistance is the' best suited for an open circuity battery of about 3 volts.

The priiiiai'y windings of

magnets

3 and 3 are of resistance of about-20() ohms, sliitable for a current of electricity fiowin througli the main lines M and L and throng i oils 30 sind 31, and through

magnets

3 and 3 to earth at E, or in other words, of about upon

electroinagnets

3 and 3 yuro wound in the saniedirectioii on the cores of the iria"- nets and do not interfere in their action wit i the cores or with tliestecl larmature 12'so that when ytlie'=aimature is-attracted to the l polegpieccs 1111s ofmagnetism is `not dissi ated by a second current passing throught e prlmary or sec ,15 be demagnetized and released from the pole pieces 1 When a suitable direct current of elect-ricity is applied to the mawin line at the central station to operate the relay in the desired direction, a current of electricity flows through

coils

30 and 31 and unites at D, and thence passes through magnets Band 3 to ground at E. This current of itself would not be sufficient to operate the switch device,

that is, to attractthe steel armature 12, but

as soon as the contact springs 6 and 8 or 9v p make contact by the operation of the olar-4 ized relay, and thereby close the loca battery circuit which includes in it the electrov magnet windings 3 and 3b, the battery current lowin throu h'y these Windinffs 1n the g g e same direction as in the primary windings ofelectromagnets 3 and `2l augments the 4ma netislu in said cores'and attracts the stee armature 12 and retains it in that condition as hereinbeforeset forth. The see` ondary or steel amature 12 upon being attracted by the pole pieces 11 closes the magnetic field of force in the clectromagnets 40 and thereby deprives the rimary armature 4 of magnetic influence. he primary armature is immediatelyrestored to itsnormal sition by the kspring 6 and opens the local attery circuit. .l A

As theoperuting current owing in the main line and through the primary wind- I ings of electromagnets 3 and` k3 is in The same direction'supon these cores, it will be understood that.l 1.,.does not vinterfere with the operation oft e switch device v'to close circuit connected to the contact .springs 16,.

t

17, 18, 19, 20 and 21. v I have` found in prac- Yice that the opening of the line connections, last named, maybe eectedpot alone byA an alternatingmirrent'ofv electricityx applied to the main operating line fn'whic device is operated, but may be accomplished by the application of a direct current of electricity to the main operating line in the opposite direction as to its polarity to thatof the initial char e or first impulse applied for the purpose o? closing the line circuits.

' But this second impulse, of course, must be of very short duration'for two reasons, First,

it must be of too` short a duration to make the switchV the polarized relay operable to close the battexy circuits, and secondly, it must be of su cient duration to repel the steel armature away from the electromagnet cores and no more. However, this lat-ter method of release,l while it is possible, I have yfound is not so simple and effective as the use of the alternating current.

The principles involved in my device may be used in apparatus slightly different from 25 the one l herein describe, and I do not Wishto be understood as confining myself to this exact type of instrument, nor to the exact combination of circuits as here shown. ln fact, the greatest utility of my invention is iu the fact that it is adaptable to greatly varying conditions and to a great number of coun bina tions of line switchlng.

A central station equipment necessary for controlling the current used for operatingr 4,my device, is illustrated, having a source of direct current G and a source of alternating current H, and cams Jand K or othcrsuitable means for applying the direct and alter- 'natiug current to the main operating liuc S0 M and L, proceeding to the sub-station switch device.

When it fis desired to connect the main operating line M and L to an independent line R and S, proceeding from the said substation and independent ot the first said main operating line, plug T isy insertedin jack V. A direct current of electricity is applied to the main line conductors with one polarity of the said current and the opposite polarity to ground at Ha by movement ot cam K to the left. When this cam is opcrated in this manner, contact springs 34, 35 and 36 are connected to the main line conduct-ors throu hcond'uctors 37 and 3S, plug T and jack and the source of directeurrent G. n The main line conductors are thereby made to receive a. current of electricity of negative polarity which flows equally over cach of the said conductors through contact with 'spring 34 which is connected to the negative pole of the source of electricity at the central station, the other ole G being grounded at H. The current o'ws ovcrthe mainlines in the manner described, thence throughv coils 30fantl31 and throuvh magnets 3 andS to the earth vat E. :T is cur rent energizes electromagnets in the polar-- -ized relay in the Well-known manner, and closes the localv battery circuits by

contactv springs

6 and 8 or 6 and 9 coming 1n contact as hereinbefore described; the direction of its movement Abeing dependent upon the polarity of the ermanent magnet '10,With respect to the po arity of the electroinagncts 3 and 3', influencing armature 4 in the Well known manner.

It will be understood that contact springs 6 and 8 and 9 normally maintain an open local battery circuit andare only closed 130 when the polarized relay is operated to do so by a current in the main line conductors, as described. Vhen the contact spring-6 comes in contact with

contact spring

8 or 9 itl closes the local battery circuit B and current Hows through the windings 3* and 3", energizing the corea.` The steel armature 12 is thereby attracted to the pole pieces 11 on said cores and retained in that condition until acted -upon by analternating current in the primawry windings of electromagnets 4 and 3', applied atthe central station in a like manner as the direct current.

The action of the alternating current in the switch device causes the steel armature 12 to be demagnetized and thereby be released from the pole piece 11 whereupon the arinature will be withdrawn by thc contact springs'lTand 20 and the circuits opened between the main line M and L, lines R and S, cont-act,y springs 16 and 21, and closed through conductors X and Z. When the secondary or steel armature is in this position it maintains the connection vbetween thc independent line R-'S and induction coil winding32-33 throuvhcontact springs 17, 1S, 19. and 20, and the central station may signal or call stations on thc independent line or lines, thus connected to thel main operating line through the-said induction,

coil by operating the cam K to the right. The alternating current-.ot electricity from source H flows through contact springs 41, 3) and 40 through conductors 357 and 38 to line M--Ji through plug T and jack V, thence through coils 3() and 31 and through the relay, thence to earth at E. This 1n (luces electricity in the

coils

32 and 33 in the well known manner and causes an alternating current of electricity to vflow in conductors X and Z and through contact springs, 17, 18, 19 and 20, to which is connected line R-S or the independent line proceeding from the sub-station.

When my invention is used in a systemes y hereindescribed, it is necessary `-in order that the independent line R--S may signal cen` tra] station, that. av means for receiviii'ur the is means consists of the ordinary switchboardidrop at thecentral station, illustratedy at. Y, v'which is'here shown connected with one side of the main line M and thence to earth -at- Y. It'is necessary that the windin of this signal'device should be of high, selzf-,inductive resistance so as to notunbalance the electrical equilibrium inthe mainoperatng line.

The central station receives ther telephone signals from the sub-station lineover main line conductor M and the earth for return circuit online drop Yat the central station. V iVhen a station on the substation line R-S operates the alternating current generator '(not shown) for the purpose of calling the ceni'gnals attlie central station be provided.

tral station, the induction il windings and 33 included in lineR-S, induces a current of-electricity in the'secondary windin of 30 and 31 of opposite polarity to the Su station line current when present in wind-

v ings

32 and 33. The induced'current in the

secondary windings

30 and 31 Hows through main line conductors M and L to the central station. The induced current in the

secondary windings

30,and 31 Hows through main line conductors M and L to the central station where winding in line' drop Y isconnected `iii circuit with the circuit M; yThe current flows through the said winding in line drop Y' tothe earth at Y. From oint E at the substation the circuit is comp eted through

relay windings

3 and 3 by conduc; tor Q at point D in the induction coil. centralstation operator upon observing the call answers by inserting plug T into sprin jack V and by operating cani J4 to thele tplaces the operators set 51- in communication withv the sub-stationline actin as one conductor and the earth at Hb and as its return circnits'in the manner described.

`When a station connected with'the sub station R-S desires to communicate with any station connected with main, line M-L, it signals the central station in the manner set forth and informsl the operator who thereupon calls the desired station upon the main line Mi-L in the usual and well known manner, that is, by the application of a, suit` able alternating current of electricity to the main line conductors M-L. Whenl the station called has answered, the central operator proceeds to place the sub-station line R-S andthe main line M-L indirect communication by the application of a direct current of electricity to the 'main line conductors M--I-J. Thisis accomplished'by operating the cani K toward the left. The source of direct current G at the central sta- The tion is grounded at Hythe direct current v flows through contact springs 34, 35, andl36 through

conductors

37 and 3 8, plugl'll and spring jacks V connected with main liuc con` ductorsM--L This direct.currentshould be of lsomewhat. higher Avoltage and amper `l` age than the current 4used for ringing ou( the mainline, as the relay at the switch device is adjusted to close thc local battery circuit upon the 'application of the 'direct current,'

but to lremain unatfected by the alternating current used in ringing stations on the niain line. The direct current when thus vapplied to the line M-L o crates the 'rela at the telephone line switcllii device and `c oses the local 'battery circuit through springs f6, `8 and 9 in the imanner .heretofore described,

telephone line switch device when the main line M--L is placed indirect connection or contact with the sub-station line A whereupon :i station ou line R-S 'thereby cutting oil the repeating coil at the" lease of the secondary 'armature from the pole. pieces 11,-and thereby restores the connections between the repeating coil, ythe Amain` line M-L and substation line R-S. l

Theil a station on line M-L desires to call the central station.. lt may do so by ring' N illg with the' telephone generator (not shown) upon the said lille, which ring will The central be received on line drop o5. operator proceeds to answer by the insertion of plug T into eitller Jack V or V, and op crates the calli J to lthe right in the manner hereinbefore described, or the call may be answered with any other lug and cord-set ili the switch-board wire in the ordinary way, by the insertion of such plug into jack V".

I have omitted details not absolutely necessar to the performance of the pur ose to wliici this device is designed; as or iiistance, the sub-stations or telephones connected with line M-L or stations upon R-S, are not shown, their mode of operation not being different from the ordinary ma neto-system of telephony.

claim as lny invention 1. The combination, with a central station lilies, of a polarized relay having primary' and secondary windings, said rimary win'd.A

lings being in circuit with sai centi-al lines, a normal y 'open local circuit having a4 suitiiected with said secondary windings, lneaiis whereby said local circuit will be closed when said relay is energized by the passage offa current through said primary windings,

said local circuit is opened, substantially as described.

.2. The combination, with a ceiit-ial station lines, of a polarized relay having priliiary and secondary windings, said primary windings being of greater resistance than said secondary windings and in circuit with said central station lines, a normally open local circuit'connected with said secondary windings nieans whereby said local circuit will be closed when raid relay is energized, substation lilies, means whereb the closing of said local circuit willestablish a circuit between said central Aand `sub-station lilies, and said inca-ns maintaining such circuit after said local circuit is opened and until an alternatingcurrent is passedl through said primary windin 3. The ,coniglis mation, with a central station lines, of a polarized relay having primar and secondary windings, said primary wint able source of, electrical energyy and con-9 ings being in circuit with said celltial station lines, a normally o en local circuit connect- -ed with said secoli ary windings a primary armature arraliged to be attracted when a current is passed through said primary windings, means actuated by the movement of said primary armature for closing-said local circuit, a secondary armature normally tween said central stationlines and said silbiiiiail'ected. by the passin of a current through said primary. win( ings biitattracted` when said current is augmented by the closing ot thc circuit tl'iroughvsaid secondary windings, sub-station lilies, and means actin i` ated -by the movement of said secondary arL mature for, establishing a connection be station lilies, aiid said secondary armature being adapted todeprive said primary armature of magnetic influence whereby upontlie attraction of said secondary armature said primar i armature will return to its normal position and said local circuit will be opened without eil'ecting vthe connection between said main lines and said sub-station lilies, substantially as described.

4. The combination, with a central station lines, of a polarized relay having primary and secondary windings, said primary windings being in circuitvwith said central station lines, a normally open local circuit connected with said secondary windings, a vsott iron armature arranged to be attracted wlien'a current'lis assed through said primary windings ang having means,-when attracted, for closing said local` circuit, a steel armature normallyniiatlected by the passage ot a current through said primary windings but attracted when a current .is passed through said secondary windings by the closingot said local circuit, sub-station lines, and means controlledby the movement of said steel armature for establishing a connection between said cent-ral station lilies and said sub-station lines, and said steel armature being adapted' to ydeprive the said soft iron armature of its magnetic influence and allow it to return to its normal position and open said local circuit,'and said steclarn'iature remaining in its att `acted position until released by the passageofiin alternating current through'said-primary windings, sub 115 s tantially as described.

In a polarized .relay having primaryv and secondary windinvs, a soft iron armature norilially attracte l 'by the passage of a ings augmenting the magnetism of said relay .sutiic'iently to attract said steel armature, and said steel armature depriving, when attracted, said soft iron -ariilatureot' its inag- 130 neticlr inliuencc, Vwhereby when said steel -passed through said primary windings, an,

induction'coi in circuit with said central station lines, sub-station. lines, and means for establishing a connection between either of said sub-station. es and either of said crrectlonP Lettersl Patent. No.` 941,743.

main lines whensaid al circuit is closed, and sald connection contlnumg after the opening of said local circuit bythe return of said armatureto' its normal position, substantially as described.

7. In a Atelephone system, the combination,- with a central station line, of a relay having prima and secondary windings, said primary windin being inv circuit with said central station ines, a ,normally open local circuit having a suitabletsource of electrical ener and connected with said secondary win ings, means whereb said local circuit will be closed when sai relay is energized b` the passage -of a current through sai pnmary windings, sub-station` lines, and means whereby the closing of said local circuit will close the circuit between the said central and sub-stationlines and `maintain such circuit'after said local crl icuit is opened. i 8. 1n a telephone system, the comblnation, with the central station lines, of sub-station circuits normally disconnected from'` [sun] :improvement inf ySwitch Devices, y requiringH fester; -ir ure greet ma primed heed e it is stated` that `said falssigned'onelfourth of his interest to T.' F. Robinson, vwhereasfit should yhave been stated that said` to Il F. Rcbinefmms shown by the of assignments inthis oce; and :het the reid Lettere retestenema lbe reed with une eerreraiee therein, that the same may conform to therecord of the case in the Patent (Mice. i I

-signed mi sealed thir'esur dey ef Deeember; A. D., 1909-.

said central station lines, a normally open local circuit provided at the sub-station, means within control of the o erator at the central station for closing sai local circuit, and means whereby the closingof said local circuit will close the circuit between the said central station linesA and sub-station cir-l cuits, substantially as described and said -means maintaining said circuit after Said local circuit is o cned.

9. In a telep one system, the combination,

Vwith a central station lines, of sub-station lines, a normally open local circuit provided at the sub-station, means within control of thex o erator at central station for closingl said ocal circuit, means whereby the closing ofsaid local circuitvwill close the circuit between the said central and sub-station lines,.andsaid means maintaining such cirstation line, and having a.y subscribers stationand means within control of the operator at the central station for closing said local4 circuitand connectin or disconnecting said central line and sai sub-station circuit, to connect a subscribers station on said sub-station circuit with the central line,

'risr without thepresence of an operator at the sub-station.

In witness whereof, I have hereunto set my4 hand this 13th day of February 19.07.

JOHN Il'l SVVANSON.

Witnesses:

RICHARD PAUL, J. B. ERA.

1tje hereby eerued, trentini-euere Peter: Ne.l 941,743, greeted November 3o, 1909, upon the, application tif-'John H. Swanson, of Baldwin, Wisconsin, for an an error lappare A f the epeeifierrtier'r in said invention SWflnsOnassigned E. B. MOORE,4 Commissioner of Pvtenu,

' netic, iniiuencc, Vwhereby when said steel armature is attracted, said sot iron arma-l ture will bey released and will return to its normal position and o en said local circuit,

s substantially as descri ed.

with said centra station induction coi station lines, sub-station. lines, and means for establishing a connection between either of said sub-stations es and either` of said main lines whensaid al circuit is closed,

2o and said connection continuing after the (IcirrectlonP Lettersl Patent. No.` 941,743.

opening of said local circuit bythe return of said armatureto' its normal position, substantially as described.

7. In a Atelephone system, the combina- 5 tion,- with a central station line, of a relay having prima and secondary windings,

said primary windin being inv circuit with said central station ines, a 'normally open local circuit having a suitabletsource of o electrical ener and connected with said secondary win ings, means wliereb said local circuit will be closed when sai relay is energized b` the passage -of a current through sai primary windings, sub-station` I5 lines, and means whereby the closing of said local circuit will close the circuit between the said central and sub-statioiilines and `maintain such circuit'after said local cirl icuit is opened. i 8. 1n a telephone system, the combination, with the central station lines, of sub-station circuits normally disconnected from'` [sun] :improvement inf` ySwitch Devices, y requise; feiieie'; in the greet ma primed heed e it isstated that said falssigned'onelfourth of his interest to T.' F. Robinson, vwhereasit should yhave been stated that said` to Il F. Rcbinafm'as sli-'own by the of assignments inthis oce; and :het the seid Lettere retestenema lbe reed with this eerreetiee therein, that the 'same may conform to therecord of the case in the Patent (Mice. i I

-signed mi eeeied thie'esth dey ef Deeembe; A. D., 1909-.

said central station lines, a normally open local circuit provided at the sub-station, means within control of the o crater at the central station for closing sai local circuit, and means whereby the closingof said local circuit will close the circuit between the said central station linesA and sub-station cir-l cuits, substantially as described and said -means maintaining said circuit after Said local circuit is o cned.

9. In a telep one system, the combination,

Vwith a central station lines, of sub-station lines, a normally open local circuit provided at the sub-station, means within control of thex o erator at central station for closingl said ocal circuit, means whereby the closing ofsaid local circuitvwill close the circuit between the said central and sub-station lines,.andsaid means maintaining such cirstation line, and having ay subscribers stationand means within control of the operator at the central station for closing said local4 circuitand connectin or disconnecting said central line and sai sub-station circuit, to connect a subscribers station on said sub-station circuit with the central line,

'iisr without thepresence of an operator at the sub-station.

In witness whereof, I hws hereunto set my4 hand this` 13th day of February 19.07.

JOHN Il'l SVVANSON.

Witnesses:

RICHARD PAUL, J. B. ERA.

nie hereby eeriiiied, cenni-euere retest Ne.l 941,743, greeted November 3o, 1909, upon the, application tif-'John H. Swanson, of Baldwin, Wisconsin, for an an error lappara o f the epeeifieetieu in said invention Swansonassigned E. B. MOORE,4 Commissioner of Pvtenu,

Correctlon in Letters Patent No.941.743.

It is hereby certified nmz in Letters Patent No. 941,743, grunted November 3o, 1909, upon the application of John H. Swanson, of Baldwin, Wisconsin, for nu 'improvement in TelephoneL-ine 'Selective Switch Devices, an error appears requiring correction,v foiio'vvsr In the grnnt and printed head of the specification it is stated that said Swanson ssignedone-fourth of his interestA in said invention to T.F. Robinson, Whereas it should have been stated that said Swanson assigned One-aafto .T E Romrm, as shown by the record of assignments in this oiiice; and that the said Letters Patent shouid be read with this correction therein, that the seme may conform to the record of the case in the Patent (Miice.

Signed ami sealed this 28th dey of December; A. D., 1909.

[5mn] E. B. MOORE,

' OOmmzasz'oner of Patents.