US511875A - Callender - Google Patents

Description

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EEALLE-NEER. TELEPHONE EXCHANGE SYSTEM. No. 511,875. Patented Jan. 2, 1894.-

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TELEPHONE EXCHANGE SYSTEM. N0. 511,875. Patented Jan. 2, 1894.

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R.GALLENDER. TELEPHONE EXCHANGE SYSTEM.

No. 511,875. Patented Jan. 2, 1894,.

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TELEPHONE EXCHANGE SYSTEM. No. 511,875. Patented Jan. 2,1894.

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R. GALLENDER.

' TELEPHONE EXCHANGE SYSTEM.

No. 511,875. Patented Jan. 2, 1894.

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R. O ALLENDER. TELEPHONE EXCHANGE SYSTEM-.1

N0. 511,875. Patgnted Jan. 2, 1894.

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(No Model.) R. GALLENDER.

TELEPHONE EXGHA'NGE SYSTEM.

No. 511,875. Patented Jan. 2, 1894. I

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UNiTnn STATES 'Arnrtr rrrone ROMAINE CALLENDER, OF BRANTFORD, CANADA.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 511,875, dated January 2, 1894.

Application filed August 13,1892.

To all whom it may concern.-

Be it known that I, RoMAINE CALLENDER, a subject of the Queen of Great Britain, residing at Brantford, Ontario, in the Dominion of Canada, haveinvented certain new and useful Improvements in TelephoneExchan e 'Systems, of which the following is a specification.

My invention is directed particularly to improvements in that type of apparatus known in the art as automatic telephone exchange systems in which the subscribers, through the agency of apparatus located at outlying stations and additional apparatus located at a central or main exchange, are enabled to antomatically efiect intercommunication with each other in any desired order.

My invention has for its objects, first, the construction of such an automatic telephone exchange system as will enable any subscriber to instantaneously effect automatically intercommunication through a central exchange office with any other subscriber and at the same time prevent the possibility of any disturbance or interruption from a third subscriber until after the first two have held their conversation or been rung ofif second, to provide means whereby a preliminary signal is first sent in to the central station, all of the lines disconnected from a common switching device and finally to connect the lines desired automatically; third, to provide means whereby any two lines of an indefinite number may be automatically connected on sending a simple make and break signal from any outlying station to the central station; fourth, to provide means whereby the subscriber signaling may make the connection desired from his own office through the central office over his own line by simply turning in a signal from a transmitter located in or near his own telephone box; fifth, to provide means whereby when a signal is turned in, a constantly operating generator located in the central station may be automatically connected in circuit with the line of the subscriber sending the signal and that of the subscriber signaled and the call bells at both stations rung, thereby indicating that the two lines are in circuit; sixth, to provide mechanism which shall enable any subscriber to connect his line with that of any other subscriber automatically; to signal the subscriber want- $erial No. 442,948. (No model.)

ed and finally after the conversation hasbeen effected to automatically ring oif both subscribers and restore the lines to their normal condition; seventh, to provide mechanism in the nature of automatic apparatus whereby any two or more subscribers having telephone instruments located on any two of an indefinite series of outlying telephone lines connected withswitching mechanism at a central stationmay effect any of the results necessarily attributable to the apparatus hereinafter described, the novel features of which are particularly pointed out in the claims at the end of this specification. I accomplish these several objects with the apparatus hereinafter described, for a full and clear understanding of which reference is had to the accompanying drawings in which- Figures 1, 2, 3, 4, 5,6,7 and 8 are diagrammatic views illustrating the entire system and for a clear understanding of which, the first eight of the sheets of the drawings should be laid side by side in sequence. Fig. 9 is a part diagrammatic part plan view of that portion of the apparatus which I shall term the isolator. Fig. 10 is a detail end elevational view of the circuit controlling apparatus which regulates the releasing mechanism of the several portions of the clock or time controlled apparatus. Fig. 11 is a plan view of the general switching mechanism whereby all of the lines which enter the exchange are antomatically interrupted when a preliminary signal is sent in from a subscriber and remain interrupted during the time that the anto matic connection is being effected between the subscriber who signals and the subscriber signaled. Figs. 12 and 13 represent diagram m'atically a complete system of nineteen lines showing the circuit connections from nineteen outlying stations to and through the automatic central station with so much of the controlling apparatus as directly influences the switching portions of the mechanism, and also illustrating in the latter figure the radiating system of connecting conductors for connecting up additional lines. Fig. 14 is a diagrammatic view illustrating the circuit connections in the central station for a system of nine-hundred and ninety-nine lines, the operating apparatus not being shown.

Before entering upon a detailed description of the drawings in order that a general understanding may be had of my novel automatic system, it may be well at the outset to indicate that all of the automatic apparatus in the nature of switching apparatus, time controlled mechanism and the magneto call generator are located at the central or main office into which the subscribers lines all enter, there being one or more sets of subscribers instruments located on'each independent line, each of which sets of instruments is provided with a circuitbreaking transmitter like that shown in Fig. 1 and lettered T, there being also a signaling battery B A for each independent line earthed at E. All of the apparatus therefore shown in Figs. 2 to 11 inclusive is located at the central station and all of the incoming independent wires on which the subscribers instruments are located run to a rotary or oscillating general circuit breaking cylinder 0 Figs. 5, 11, and 13, their electrical continuity being maintained through a series of metallic contact plates or strips 6 on the upper surface of this cylinder.

In order to simplify the illustration, I have shown a single outlying line numbered 1, Fig.

, 1, earthed at E and provided with the usual lightning arrester L, Blake transmitter T transmitting battery B A, receiving magneto telephone T hung upon its hook in the ordinary way, all of the circuit connections thereof for the transmitter T and receiver T being what is now well understood by those skilled in the art; the right hand side of the lightning arrester L being connected by the subscribers line 1 to and through the upper portions of Figs. 2, 3 and 4 to the general circuit breaker C (Figs. 5, 11 and 13) through the contact springs 3 metallic plates a to No. 1 of a series of contact plates numbered from O to 9 which in turn are connected through corresponding subscribers wires and similar apparatus located at like outlying stations.

In the telephone box of each subscriber or at some point easily accessible to the subscriber, is located a rotary transmitter T consisting of an insulating cylinder having a series of ten metallic strips or successively of different length located upon its surface and electrically in contact with the metallic axis of the cylinder which in turn is connected through a contact spring y with a signaling battery B A earthed at E. The number of these metallic plates at is equal to that of a corresponding set of conductingsprings a the free ends of which are adapted to bear upon the cylinder T and make contactin succession with the plates a, While their other ends are secured to a fixed set of electrical conducting plates numbered 0, 1, 2, 3, &c., to 9, inclu sive, said contact plates being lettered 0 and corresponding in number with the number of subscribers lines under the control of the first portion of the apparatus at the central station which I denominate as numerical reoeiver No. 1. See Figs. 5 and 13.

S w is a rotating conducting switch the free end of which is adapted to contact with the ends of the conducting plates 0 and M B is a magneto call bell electrically connected on one side to the lightning arrester L with the earth E and on the other through a pair of conducting springs 25 with a short conducting plate z' carried by the cylinder T and in turn through the telephone hook with the subscribers line 1 as clearly shown.

The rotary transmitterT with the transmitting batteryB A and the circuit connections just described constitute the only apparatus used by me at the subscribers stations for efiecting automatic intercommunication through a central station with outlying subscribers on independent lines.

I shall now describe in general terms the apparatus located at the central station, after which I shall describe the mode of operation of the entire system.

In Fig. 6 is shown at the bottom of the drawing, a battery B A and a series of circuits numbered 12, 7, 14, 17, 22 and 24 running to step by step mechanism illustrated in Figs. 2, 3, 4, 5, 7, 8 and 13. These several circuits are automatically opened and closed at the points q g by one or more conducting extensions m of a pendulum R carried by a clock beating seconds or any other preferred elements of time, P being the pendulum ball. I have shown this method of closing these several circuits by a single conducting extension m and through the agency of a pendulum for the reason that this is the simplest method of illustrating this portion of the apparatus. It will be understood that it would of course be preferable to provide independent circuit closing contacts q q for each circuit 12, 7, 14, 17, 22 and 24 and that the circuits might be closed with sliding contacts carried by a rotary drum adapted to make one revolution in any desired time or that there might be a separate rotary drum for each set of contacts and each controlled by an independent clock mechanism and adapted to rotate each at such a speed as the necessities of the case might demand.

Referring now to Figs. 2, 3, 4, 7 and the lower part of 8, that portion of the apparatus which discloses ratchet wheels or ratchet sectors with holding and propelling pawls and operating electro-magnets together with releasing devices are all controlled directly in their forward action step by step by the clock mechanism shown in Fig. 6.

That portion of the apparatus at the bottom of Fig. 2 lettered E I term the general time limit apparatus, its object being to operate for a specified length of time under the control of the clock (Fig. 6) during which time the subscriber shall have had an opportunity to complete his signal and make the circuit connection with thesubscribersought, after which this portion of the apparatus is automatically released and conversation proceeded with as will be fully described later on.

ft I O0 That portion of the apparatus illustrated in Fig. 3 by the letter O I denominate as the magneto signaling controlling instrument, its function being to automatically connect the constantly driven magneto signaling generator H in a looped circuit between any two subscribers lines after they have been automatically connected together through the central station.

That portion of the apparatus represented at the bottom of Fig. 4 and lettered C I denominate as the numerical separator, its function being to enable any subscriber to select a certain one of the remaining subscribers lines where the total number of those lines amounts to more than nine: that is tosay, by the use of the switch S10 and the transmitter T for one revolution of said transmitter the subscriber may connect his line with the desired one of the lines 0 to 9 in Fig. 5, but when the outlying subscribers lines amount to more than nine it will be necessary to make two or more revolutions of the transmitter T and to correspondingly change the location of the switch S w to any one of the desired numerals O, and 1 to 9 inclusive, between which revolut-ions of the transmitter this and other like numerical separators act to aid in bringing about the desired connection as will be fully described in connection with the description of the mode of operation. To make this statement last made more clear, it is to be understood that for the first system of outlying subscribers wires illustrated in Fig. 5, the switch handle S w is to be placed upon that one of the conducting strips 0 O to 9 inclusive corresponding to the subscribers wire wanted and one revolution given to the transmitter T by the handle H and that for connections between the subscriber and any higher number of outlying subscribers circuits, such as is shown in Fig. 8, the switch handle S 20 would be placed upon any one of the conducting strips 0 to 9 corresponding to the subscribers wire wanted in the higher number than nine and the transmitter T given a second rotation. In the meantime the numerical separator illustrated at the bottom of Fig. 4 will select the circuits of the higher order of numerals from those of the lower order of numerals during the interval of time between the two rotations of the transmitter T as will be fully described in the description of the mode of operation.

That portion of the apparatus illustrated in the upper portion of Fig. 5, I denominate as numerical receiver No. 1. It consists of a ratchet wheel W' and conducting arm D, operating electro-magnet R and releasing electro-magnet d, propelling pawl 72., holding pawl k releasing cord 0 passing under pulley b and releasing armature lever Z V being a weight attached to a cord passing over a pulley n and secured to the shaft of the wheel WV,the function of the conducting arm D being to convey the current from the subscribers wire to the desired outlying subscriber whose wire is connected with one of the conducting plates 0 to 9 inclusive. This numerical receiver is positively propelled by the action of the electro-magnet R and pawl b through current impulses sent over the signaling subscribers line by the transmitter T when rotated, as already described.

That portion of the apparatus illustrated at the bottom of Fig. 5, I denominate as the general circuit breaking instrument, the same being illustrated in plan view in Figs. 11 and 13, and controlled by electro-magnets d and d armature levers Z Z propelling pawl h and releasing pawl k releasing cord a passing under the pulley b That portion of the apparatus illustrated in the upper portion of Fig. 7 and lettered G I denominate as the adjustable automatic conversation time-limit mechanism, its function being to regulate the time for which the conversation between the subscribers may be held, and it is controlled by electro-magnets (1 d, and (7/ with propelling pawl h releasing pawl releasing cord 0 passing under pulley Z)".

That portion of the apparatus shown at the bottom of Fig.7 and lettered (3 ,1 denominate as the automatic release controller which releases all of the apparatus not already released when the adjustable automatic conversation time-limit restores all of the apparatusat the central station to normal condition ready for the next signal.

That portion of the apparatus shown near the top of Fig. 8, I denominate numerical receiver No. 2, it being a mere extension of the like portion of the apparatus shown in Figs. 5 and 13 and denominated numerical receiver No. 1 each one of the several subscribers lines numbered from 1 to 9 inclusive, Figs. 5 and 13, being connected to an instrument like numerical receiverNo. 1. In other words each subscribers line running out from numerical receiver No. 1 in Fig. 5 would be connected to a corresponding conducting arm D on a second numerical receiver adapted to be connected with any one of a secondary set of subscribers, like that shown in Figs. 8 and 13 thereby largely increasing the connecting capacity of the system.

A more clear understanding may be had of the arrangement of the numerical receivers or switching apparatus which connect up the various lines with each other, on examination of Fig. 14:, where the first numerical receiver or numerical receiver No. 1 is shown at the bottom of the drawing, and through which all incoming signals pass for all lines of the entire system. The second series of numerical receivers, each of which is always denominated as numerical receiver No. 2, whenever referred to in this specification, is seen immediately above numerical receiver No. 1; and the third series of numerical receivers, each of which is always denominated as numerical receiver No. 3, whenever referred to in this specification, is located above the second series and all signals of the third order of decimals pass these receivers, as will be more clearly understood in connection with the description of the mode of operation. This figure of the drawings just referred to shows the circuit connections only for the entire system of lines and the numerical receivers for. connecting them together in pairs in any desired order, it being understood that auy incoming signal from any outlying subscriber is conveyed first to numeri cal receiver No. 1, thence through that one of the second series of numerical receivers denominated as numerical receiver No. 2 which is called, and thence through that one of the third series of numerical receivers which is called, it being understood that all lines from 1 to 9 inclusive may be called through numerical receiver No. 1 only while all lines from 1 to 99 inclusive are connected with each other only through numerical receiver No.1 and the necessary one of the second series connected to the line wanted. In

other words all incoming signals of any nature whatever must pass through numerical receiver No. 1. All incoming signals of the second order of decimals or from 1 to 99 inclusive must pass through numerical receiver No. l and one of the second series of numerical receivers. All signals from 1 to 999 inclusive must pass through numerical receiver No. 1, some one of the second series of numerical receivers and some one of the third series of numerical receivers.

That portion shown at the bottom of Fig. 8 of the drawings is a'd'uplicate numerical separator and is identical with that shown at the bottom of Fig. 4 of the drawings lettered Referring now to Fig. 2; L L are switches controlled by magnets M M ing magnet for releasing the weighted switch lever 1 there being one of these releasing magnets for each subscribers line and all operatively connected with the circuit 8 with the releasing mechanism controlled by the adjustable automatic conversation time-limit apparatus illustrated in Fig. 7.

S, S and S", Fig. 4, are releasing magnets operated either by the transmitter T or by the apparatus connected to the adj ustable automatic conversation time limit.

S and S S, Fig.4, are switches controlled by electro-magnets M M M and M.

S and S S Fig. 8, are substantial duplicates of the switches S and S S shown in Fig.4.

K, K, K, K, K, Figs. 3, 4, 5, 7, and 8 are ratchet segments adjustably secured to the rotary parts 0, C O O and 0 (see Fig. 8,) the size and number of the ratchet teeth being made dependent upon the proportionate times in which it is desired to rotate the disks or cylinders to which they are attached.

W W W WV? are weights carried by levers pivoted to the frame of the apparatus,

their inner or free ends bearing under or be-' neath the curved portions of the sectors K so that as the disks are rotated the weights V d is a releasare lifted and when said disks are released, these weights acting through the levers will cause the disks and sectors to assume their normal positions. In place of these weighted levers I may use weights and cords passing over pulleys like those shown at W and n in connection with the ratchet wheel of the general time limit apparatus in Fig. 2.

Referring now toFig. which is an enlarged view illustrating different positions of the circuit cont-rollers carried by the rotary disks or cylinders C, 0 C and 0 t is a strip of conducting metal secured at one end to one of the conductors running to a releasing electro-magn et, in this instance shown as the conductor 11, running to the releasing magnet d Fig. 2, and t is a corresponding conducting plate secured to the edge of the disk 0', this plate being in turn connected to'the other end of the conductor 11. t is an elastic or yielding metallic plate carried also by the disk 0 but insulated from it and the plate The upper or straight edge of this yielding metallic plate t lies snugly against the end of the disk 0', and the lower or V shaped edge is curved outward from the end of said disk and so'thatit is out of electrical contact with the fixedinnerplatef,thearraugement beingsuch that as the disk 0 rotates in the direction of the arrowin the first position the free end ofthe metallic plate 6 rides up over the outwardly curved end of the plate 1 so that there will be no metallic contact between the contacting plate t and the fixed plate 25 carried by the disk 0 until it leaves the upper curved or angular surface of the insulated plate 2' and assumes the position shown in the central figure, while on rotating the disk 0' in the reverse direction as shown in the right hand of thefigure, the plates 25 and 25 will be in metallic contact as the former passes under the insulated plate 2' and maintains contact between the plates and t until the disk assu mes its original position and passes out from under the end of the yielding plate 71 as said disk rotatesin the direction of the arrow shown in the right hand portion of Fig. 10. The action of these corresponding parts in Figs. 8, 4, 7and8 in connection with the disks 0', O O 0 and (J is the same and the releasing electro-magnets d (1 d, d, and 61 are adapted to release said disks at the proper intervals of time.

I will now describe the mode of operation of the entire apparatus giving first a description of the method of connecting up two subscribers where the number of the subscribers wires so connected lies between one and nine, and then describe the method of connecting up two subscribers where the number of Wires is over nine, thus illustrating in the second instance how, with a limited number of wires connected to each numerical receiver or two or more sets of such receivers, I may make connections between a large number of outlying subscribers wires. Suppose in the firstin- IIO stance itis desired to connect the subscriber on v wire No.1 and whose signaling and telephone instruments are shown in Fig. 1 with another subscriber whose instruments are located on say wire No. 9. The several parts of the apparatus at the outset are in the position shown in the drawings of Figsl toS inclusive and in full lines in Figs. 12 and 13. The operator on wire No. 1 turns the switch S to into contact with that contact plate 0 numbered O and then rotates the transmitter T through the agency of handle H one complete revolution, thereby sending to line in the direct-ion of the tailless arrows a single impulse from battery B Aby wire 1, switch leverZ (Fig. 2) wire 2, weighted switch lever Z wire 2, relay R, wire 2, relay R, earth E thus actuating these two relays Band B. The relay B being energized causes its armature to close the circuit of battery B through the circuit 4t4: and magnet 61 (Fig. 5) thereby causing the armature lever Z and propelling pawl 71 to act upon the ratchet sector K and rotate the general circuit breaker C a fractional part of a revolution interrupting the circuits of all lines in the group, thus disconnecting all of the local branch lines in the central station connecting the numerical receiver between the metallic strips 6 and the series of contact springs s more clearly shown in Figs. 11 and 13. At the same instant the relay R which was energized as already described, causes the armature lever r to be drawn down so that the hook lever 7L2 near its right hand end catches the free end of the weighted switch lever Z The cord 0 attached to the other end of the armature lever r and to a detent hook his simultaneously drawn down over the pulley 1), thereby drawing the hook h out of the path of a catch on the face of theisolator cylinder I, there being a separate relay R and corresponding circuit and mechanical connections for each of the incoming subscribers lines 1 to 9 inclusive as shown in Figs. 9 and 12, the arrangement being such that the operator signaling will draw his particular detent hook it out of the path of its catch, while the remaining detent hooks h will remain in the paths of their catches. At the same instant that the armature r is drawn down by the relay R a local circuit 3 will be closed from the battery B to the local electro-magnet d imparting to its armature Z and a detent hook ha forward motion,thereby rotating the isolator cylinder I a fractional part of a revolution and allowing a detent pawl 13 to fall behind a stop on a disk attached to the shaft of the isolator cylinder. This forward motion of the isolator cylinder causes all of the switch levers Z (see Figs. 2 and 9) to be tilted forward under the influence of their hooks it except that one which has just been described as having been disconnected from the isolator cylinder by the cord 0. It

will thus be seen that the circuit isinterrupted between all of the incoming subscribers wires at the switch Z and the contact points a by this action of all of the switch levers Z except the one last referred to, so that no circuit can now be closed for incoming signals from other outlying subscribers instrum ents.

It is to be noted also that the clock or other time mechanism illustrated in Fig. 6 is supposed to be running continuously, thus constantly making and breaking the circuit of the battery B A between the yielding contact springs q q and through the circuits 12, 7, M, 17, 22 and 2t and apparatus connected therewith when any of said circuits are closed at other points as will be described later on. The preliminary impulse sent in by the transmitter T through contact plate 0 switch S w and circuit No. 1 as just described, has thus disconnected all of the outlying subscribers lines, save the one who has just signaled. As soon therefore as the relay E (Fig. was demagnetized, its armature r and hook lever 72/ shifted the circuit from the lower contact point a; at its left hand end to a second contact point 00' j ust above, and a new No. 1 circuit was established by wire l,left hand switch L,wire I, right hand magnet M of the right hand switch L thence by wire 1 through back contact stop of the armature lever of relay R and finally through relay R to earth at E both of said relays being found in Fig. 3 of the drawings. The electro-magnets R R 850., which control the movements of the numerical receivers and the switching magnets S S &c.,Fig. 8, which control the circuits in connection therewith, should be somewhat more sluggish than the relays R and B, Fig. 2, in order that the preliminary impulse sent in from any outlying station may not affect such of those magnets as may be in circuit before the branch circuits are all interrupted at the general circuit breaker; or the same may be effected by utilizing a signaling battery B A, Fig. 1, at each subscribers station of considerablyless electro-motive force than the battery B A, Fig. 3, which controls the aforesaid electromagnets. The operator at station 1 now places the switch S w in contact with plate No. 9. Supposing he desires to connect his wire with some subscriber on wire No. 9. He then gives to the transmitter '1 one complete revolution as before, thus sending ten impulses over the line in the same direction as before through lever 7?,(Fig. 2,) upper contact 03, wire 1, left hand switch L, wire 1, right hand portion of magnet M which controls and turns the switch L thence through relay R to earth at E at the bottom of Fig. 3 as already described. These ten impulses therefore actuate the relay R and cause the battery B A at the bottom of Fig. 3 to send ten successive impulses forward from earth E by armature of relay R and front contact stop by wire 1 through the left hand switch S, (Fig. 4,) thence through wire 16 and right hand magnet M which controls the two point switch S S, (Fig. 4,) thence by wire 16 through electro-magnet R to earth at E These ten impulses therefore impart to the numerical receiver No. 1 in Fig. 5, ten forward steps through the agency of the hook h and retaining pawl k thereby placing the conducting arm D of this'receiver ultimately in contact with the right hand plate 9 as clearly illustrated in dotted lines in Fig. 13 and hence withithe circuit running to the subscriber desire Returning now to the right hand switch L at the top of Fig. 2, it will be seen that by the act of shifting the lower end of its switch arm to the lefta clock circuit is established from the battery B A (Fig. 6) by way of the conductors 7-7 which circuit includes the actuating electro-magnet d at the bottom of Fig. 2 so that as the pendulum vibrates the generaltime-limit apparatusE issetin motion through the operation of the armature lever Z and propelling pawl h This mechanism continues to advance step by stem for a period of say twenty seconds or twenty beats of the clock pendulum and during the first fifteen seconds of this forward motion, the contact plate e of the general-time-limit apparatus is brought under the two conducting springs s 8, while the holding pawl retains the apparatus as it is advanced step by step and the restoring weight and cord W are drawn up over the pulley n. When the contact plate (2 passes beneath the conducting springs s a new clock circuit 12 is established through the contact points q q and battery B A said circuit 12 including an actuating electro-magnet d for the magneto signaling controlling instrument represented by the letter C (Fig. 3) so that the ratchet sector K through the agency of the propelling pawl h, armature lever Z and retaining hook 7c is caused to advance step by step as the clock closes the circuit at q q in Fig. 6. During the first of the forward steps of the tooth sector K and hence of the magneto signaling-controlling apparatus 0, the conducting plate e carried thereby is brought under the two conducting springs s s and an additional circuit is thereby closed through the conductor l3l3 from the battery B which circuit includes a releasing magnet d for the general circuit-breaker shown at the bottom of Fig. 5, thereby performing two functions at the same time: namely,first releasing the general circuit-breaking cylinder 0 through the agency of the armature lever Z releasing cord 0 propelling pawl 7L6 and detent pawl I0 and allowing this cylinder to assume its normal position or that now shown in Figs. 5, 11 and 13, thereby again restoring all of the subscribers, circuits into through connection with the contact plates a and the numerical receiver circuits, as clearly shown in Figs. 5, 12 and 13. It will be noted at this time that although the general circuit has been re-established for all of the local branch circuitsatthegeneralcircuit-breakerasshown in Figs. 5, 11 and 13, all of the subscribers circuits except the signaling circuit are now broken at their points of juncture with the switch levers Z by virtue of the previous rotation of the isolator cylinder I so that there is only one path for an incoming current.

The circuit 13 which includes the battery B contact springs 8's and the releasing magnet 03 includes also a relay R located near the bottom of Fig. 3, and it is therefore apparent that during the time that the conducting plate (2 of the magneto signaling controlling instrument 0 remains under the contact springs s s the armature of relay R will be held forward on its front contact stop. The result therefore is that the constantly operating magneto generator H is now looped in circuit with both of the incoming subscribers lines 1 and 9, and the magneto bells M B at both stations continue to ring during the time that the contact plate e is under the springs s's. As the instrument 0' continues to rotate circuit is made through conductor 9 and contact springs 25 and t and the battery circuit B near the center of Fig. 3 is closed through circuit 9 including the releasing" magnet d", (Fig. 5,) the right hand magnet of the left hand switch L at the top of Fig. 2 and the left hand switch magnet M of the switch which controls the adj ustable-conversation-time-limit apparatus in Fig. 7. Consequently the left hand switch L at the top of Fig. 2 is turned with its lower point in contact with the left hand contact point as shown in dotted lines in Fig. 12. The contact spring t of the magneto controller'O, Fig. 3, has ridden over the insulated plate 2' and assumed the position shown in the central View of Fig. 10, thereby closing the circuit of battery B through wire 11 t0 the releasing magnet cl thus releasing the generaltime-limit apparatus E in Fig. 2, and allowing it to return to normal position, it having first advanced far enough to close the circuit 10 through contact springs t with a conducting plate 0 so as to energize the left hand magnet M of the right hand switch L at the top of the drawings and return it to normal position thereby rupturing the clock circuit 7 7. The general time-limit apparatus for controlling the time of turning in the signal has been returned to normal position and has shifted the switch of the right hand switch L its at the top of Fig. 2 to its normal position, the

magneto signaling controlling instrument has been returned to normal position through the agency of the releasing magnet d and the magneto generator cut out of circuit. The adjustable automatic time-limit conversation apparatus has been set in motion through the agency of the circuit 9, magnet M and switch S to (Fig. 7) a circuit having been established through said switch, the conductor 2e, operating magnet d and the clock circuit at Fig. 6.

It will be noticed that the circuit 9 is provided with circuit closing devices at two points, one on the apparatus O'in Fig. 3, and the other on the general time-limit apparatus E in Fig. 2, the arrangement being such that although electrical contact is made between theplates t and i as O advances, the circuit will notbe closed between the plate 7? and the rotary plate carried by thegeneral time-limit apparatus until the latter has been released and returned to normal position thereby allowing the general time-limit apparatus to be released first and to afterward release the instrument and to perform the other functions already described. lVhen the relay B (Fig. 3) closed the circuit from battery B A through line 1, the left hand switchS of Fig. 4 and the right hand magnet M wire 16 and magnet B (Fig. 5) the first impulse sent over the line caused the two point switch S S to reverse its position and to close the clock circuit 17, thereby starting the numerical separator C almost simultaneously with the general time-limit apparatus (Fig. 2). As the numerical separator advances under the action of the armature Z and hook lever h it brings the contact plate e under the contact springs s 5 thereby closing a local battery circuit 15 from battery B through the left hand magnet M of the double switch S S restoring the switch to its normal position and also through the left hand magnet M of the switch S shifting said switch into the reverse position and hence directly in circuit with the arm D of the numerical receiver in Fig. 5 so that the magneto call currents from the magneto generator H were caused to take the path through the conductor 1, joining the two circuits thus connected togetherduring the time that the armature of relay R was held forward on its front contact stop, while the contact plate 6 of the magneto signaling controlling instrument was passing under the springs s s. The uninterrupted talking circuit therefore between the two lines 1 and 9 is as follows. Passing from the earth at station 1 in the direction of the tailless arrows through the wire 2 (Fig. 2) lever Z, wire 2, lever Z upper contact :1." upon which lever Z is held by hook 7L2, wire 1, switch L and left hand contact point upon which it is now resting, wire 6 through ringing otf magnet S in Fig. 4, wire 6,.wire 1 directly to the numerical receiver through the arm D to the wire 9 and thence through the contact springs 5 3 metallic plate 6 on the general circuit breaker directly to the outlying subscriber. See also Figs. 12 and 13. As the numerical separator advances through its complete phase the local circuit of battery B seen at the bottom of Fig. 4 is closed through the electro-magnet d and conductors running to the contact plates 25 and t the operation being the same as already described in connection with like parts illustrated in Fig. 10, the releasing armature lever Z causing the hook lever 71 and detent hook k to allow the sector K and disk 0 to return to normal position. Just before the magneto signaling controllinginstrument was returned to its normal position by the releasing electro-magnet d in circuit 9 and at the instant that the general-time-limit apparatus returned to its normal position and closed the circuit 9-9, the switch S 10 of the ad ustable automatic conversation time limit apparatus (Fig. 7) was turned into its upper position under the influence of magnet M which is also in circuit 9 so that after the magneto signal has been sentin and the two subscribers connected together as already described, this adjustable automatic conversation timelimit apparatus is now put in operation by the agency of the clock circuit 24 which runs to the clock and energizes the propelling electro-magnet- (1 thereby causing the sector K of this apparatus to advance step by step for a definite number of seconds or minutes or such time as may be allowed for conversation, the apparatus shown in Fig. 7 of the drawings merely indicating the application of this timeliniit principle. As the two subscribers converse therefore the apparatus C advances and ultimately the contact plate e rides under the conducting springs s 5 closing the circuit of the battery 13 through the conductors 18 to the releasing electro-magnet S near the center of Fig. 4 of the drawings, thereby lifting the armature lever 21 and allowing the armature lever o to be Withdrawn from the notch on the under side, thus locking the armature o in its upper position in contact with a conducting contact connected to the clock circuit 14. On the first closure of the clock circuit therefore through the circuit 14 the left hand switch S of Fig. 4is shifted by magnet M to its first or normal position and simultaneously the automatic releasing mechanism at the bottom of Fig. 7 is stepped forward under the influence of the electro-magnet (1 until the contact plate 6 is carried under the contact springs 3 thus closing the battery circuit B through the conductor 8 and right hand electro-magnet Mflshifting the conversation-time-limit switch S 10 back to its normal position simultaneously energizing the releasing electro-magnet 01 in the same circuit, thereby releasing the adjustable automatic conversation time-limit mechanisin and allowing it to rotate back to its normal position. At the same instant the releasing magnet d in the same circuit, 8, of the numerical receiver in Fig. 5 is actuated, allowing the weight .W' to return the conducting arm D of the numerical receiver to its first or normal position. The electro-magnet s of the ringing off apparatus F Fig. 4, is also caused to draw the armature 7) into its forward position and release the armature o. The electro-magnet M of the upper left hand switch L in Fig. 2 being in the same circuit 8 causes the switch to be turned to its first or normal position and the releasing magnet al which is also in circuit 8 in Fig. 2 lifts the pawl p and allows the isolator cylinder to be restored to its normal position. The releasing magnet cl which is also in circuit 8 in Fig. 2 is caused to release the armature lever hook 72. from the end of the Weighted lever t thereby allowing said lever to assume its original the isolator cylinder, Fig. 2.

or normal position. Lastof all theautomatic release itself at the lower part'of Fig. 7ofthe drawings is effected through the agency of a local circuit and electro magnet (Z in the same manner as the apparatus 0 at the bottom of Fig. at was released as heretofore described. It is nowapparent that the several parts of the apparatus put in operation from the transmitter Tat the station ofthe signaling subscriber have served their various functions in sequence and that the adjustable automatic conversation time limit apparatus having limited the time of the conversation, the entire mechanism at the central station has again assumed its normal condition and that the isolating cylinder I has again connected all of the outlying subscribers lines With the signaling receiving mechanism for said lines at the central station. Any other operator may now turn in his signal and automatically connect his particular line with any other line in'the system, the operation being identically the same as has heretofore been described. Should any subscriber attempt to signal during the time that tne apparatus isin use by reason of a signal previously sent in, it is apparent that he will receive no signal on his own magneto-bell, his line being like that of allsubscribers, save the one who has previously signaled, out out at He must wait therefore until he obtains a signal on his own bell on turningin a signal before he is aware of the fact that his proper circuit connections have been made. The absence of such a return signal is indicative to him of the fact that the system is in use and that he must wait until the proper circuit connections are again automatically made at the central station. It is to be understood however that although all of the subscribers outlying lines, save the one who is signaling, have been cut out of circuit at the isolating cylinder (Fig. 2) for transmitting signals, all of said lines are still connected with the numerical receivers for receiving signals at the points 0 to 9 inclusive over which the conducting arm D passes and also through the contact springs s s and conducting plates a the latter attached to the general circuit-breaking cylinder 0 (See Figs. 5 and 13.)

I will now describe how I am enabled to unite two or more subscribers instruments located in independent outlying subscribers lines where the number of such outlying lines is greater than nine.

My system of uniting any two of an indefinite number of subscribers lines is based upon What I term the units, tens, and hundreds principle, and I connect the first nine subscribers lines running into the central station with a numerical receiver which is connected to ten local or branch wires, each one of these local or branch wires being connected in turn to one of a series of secondary numerical receivers having in turn ten similar connections, each one of which runs to one of a series of third numerical receivers and so on indefinitely. Automatlc switching apparatus is also included in circuit between the several numerical receivers whereby the circuit connections are shifted so that the main battery B A at the bottom of Fig. 3 is caused to automatically advance the numerical receiver and its conducting arm D to the desired point through the agency of the relay R (Fig. 3) and the electro-magnet R (Fig. 5) and then shift the circuit connections from this electro-magnet R to the electro-magnet of the next succeeding numerical receiver and so on in sequence, the main battery B A being utiliZed to drive these numerical receiversin succession. In other words, the first n umerical receiver makes connection directly for nine subscribers wires and these connections are in turn connected to one of a series of secondary numerical receivers, each of which has provision for connections to one of a series of numerical receivers of the third order,- the number of possible connections therefore being in geometrical progression and the circuit connections through the primary numerical receiver being adapted to connect up the individual subscribers connections through the additional numerical receivers in any desired order.

Fig. 14 of the drawings shows a system approximating a thousand subscribers lines with circuit connections at the central or switching station through the isolator, the general circuit breaker, and three series of numerical receivers. The apparatus for operating the isolator, the general circuit breaker, and the numerical receivers is not shown in this figure of the drawings, nor are all of the one thousand subscribers lines shown, the

diagram being in the nature of a skeleton which illustrates only a sufficient number of such lines to give a correct understanding of the switching circuits through the exchange.

It will be understood that all the subscribers lines come into the office at the top of the drawings and divide each into two branches, one of which is connected to the isolator and the other to the general circuit breaker in the manner already described and that all of these lines are broken at the isolator when the preliminary signal is sent in except that line over which the impulse is transmitted, and also that the other branches are simulta neously broken at the general circuit breaker until the proper connections are automatically made through the various series of numerical receivers and circuit connections, after which it (the general circuit breaker) is restored to its normal position, the isolator remaining in its abnormal position until the conversation is through, so that all of the subscribers lines are :disconnected at the isolator during the conversation except that of the subscriber who signaled and that it is automatically released by the act of ringing off, after which any other subscriber may in like manner obtain control of the isolator and

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