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Publication numberUS253080 A
Publication typeGrant
Publication dateJan 31, 1882
Filing dateOct 28, 1881
Publication numberUS 253080 A, US 253080A, US-A-253080, US253080 A, US253080A
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
District-telegraph system
US 253080 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

(No Model.) 2 Sheets-Sheet 1.


DISTRIGI. TELEGRAPH SYSTEM. No. 253,080.. 'Patented Jan. 31,1882.





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(No Model.) 2 Sheets Sheet 2. G. F. MQGULLOH.

DISTRICT TELEGRAPH SYSTEM. No. 253,080. Patented Jan. 31,1882.

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SPECIFICATION forming part of Letters Patent No. 253,080, dated January 31, 1882.

Application filed October-2S, 1881. (No model.)

To all whom it may concern:

Be it known that I, OHAUNGEY F. MOGUL- LOH, of Baltimore city, State of Maryland, have invented certain new and useful lmpror'ements in District-Telegraph Systems; and I hereby declare the same to be fully, clearly, and exactly described as follows, reference being had to the accompanying drawings, in Which- Figure 1 is a plan view, illustrating the arrangementof apparatus in the central office in connection with several circuits. Fig. 2 is an elevation of the signal-box mechanism; Fig. 3,

a plan of the device for making and breaking connection, and Fig. 4 a similar view of the switch and relays.

My invention relates to district-telegraph systems or fire-alarm telegraphs in which a number of stations are in circuit with a central office; and it has for its object to obviate what has heretofore been a source of great annoyance and of loss both of time and money.

In telegraph systems of the class referred to as heretofore constructed and used-with relays, registers, and gongs in the central office-the breakage of the line has either resulted in the cutting out of the stations beyond the break or in making the entire circuit inoperative until the break is located and repaired. I have succeeded in remedying this evil and in producing asystem in which the occurrence of a break is instantly signaled at the central station, where means are afforded for immediately making the entire circuit as efficiently operative as if no break had occurred. In a word, nothing short of two simultaneous breaks, one on each side of a station, can throw it outof communication with the central office, and even then the other stations of the same circuit are unaffected. This I accomplish by connecting the several stations of the circuit with the main office by Wire, making a metallic circuit, and providing each station, as well as the central ofifice, with a ground-connection. These ground-connections are all normally open, so that the occurrence of a break is instantly made known at the central office, where, the ground being then thrown on, a circuit is set up as each box is operated. Provision is also made at the central ofiice for detectin g an accidental grounding of either part of no bad result.

of the wire in case of a break, and for obviating it, so that both parts of the broken cirpasses over the wire; but in the event ofabreak the return is through the ground. The occurrence of a break is instantly made apparent at the central office by the stroke of the gong and the starting of the register. that the boxes on both sides of a brake being grounded when in operation, all the signals are recorded, what was theretofore a closed metallic circuit becoming after the break two circuits, each having a ground-return. These circuits are just as eflicient as the closed metallic circuit, and a single break is productive As soon as one occurs, however, a lineman is sent out to repair it, because, until this is done, a second break on either side of it will cut out all the intermediate boxes. This contingency can manifestly not be guarded against; but it is very remotely possible that a second break will occur before the first can be repaired.

In the accompanying drawings, Fig. 1, are shown the usual paraphernalia of the central office and their circuits to a. b b c 0, having each a number of stations, A B 0. These stations are all connected by a main-line wire with the officefwhere they are attached, as usual, to disk-switches 25 25 25 of the ordinary construction. 22 is the local battery; 10, the No.1 main battery; 11, No. 3 main battery; and 12, theextra battery, to be used on any of the circuits of the switch-board. The extra battery'12 is connected by the wire 1, leading through the relaylS, with the right lower segment of each of the upper-disk switches, the wire from the other pole of the battery leading through the relay 17, by the wire 2, to the corresponding segment of each of the lower disks. The No.1 (10) main battery is connected by wire 3 with its relay 24, from which the wire 3 continues to the left lower segment of the disk 25, which latter is normallyin electric connection with the upper half of the disk through a plug, 26. From the upper half of the disk the current traverses the line a a, returning to the It is obvious upper halfof the lower disk 25, which is connected with the left lower segment of the same by a plug, 27, and thence by the wire 4 to the battery. Such is the normal arrangement of the circuit a a with reference to the battery 10 and disk-switches 25, and it is the usual and well-known arrangement. Double cords 5 5, having split plugs on their ends, connect the first circuit, cm, with the second, I) b, as shown. The third circuit, 0c,is connected from the upper half of the disk 25", by plug 28, with the lel't lower segment of the upper disk; thence the current passes by wire 6, through relay 23, to one pole of the battery 11,No. 3. From the opposite pole the wire 7 leads to the left lower segment of the lower disk 25"; thence through the plug 29 to the upper half of the disk and wire 0. The wire 8 from the local battery 22 leads primarily to the relay 23, which closes circuit with the wire 9, leading to the gong and register 16 of the circuit 0 c; thence the curreutreturns, by the wire 8, to the other pole of the battery. The other circuits, a a b b, are connected, as usual, with the local battery and their relay 24, gong 13, and register 14. From the wire 8 leads a tap or loop, 9,to the register 21, gong 20, relays 18 17, and by wire 10 vthe current is led to the wire 8 and to the opposite pole of the local battery. From the center cell of the extra battery 12 leads a wire, 30, to a double-lever switch, 19, having a groundconnection, G. From the switch 19 lead wires 37 38 to the wire 2, as shown. Each station A B G is provided with a normally-broken ground-connection, Gr.

Such is the general arrangement of the apparatus, and its operation may well be described before goin g intoa detailed description of the box mechanism shown in Figs. 2 and 3. Suffice it here that the. latter has a ground connection, normally broken, but so arranged as to close to make the signal. Now suppose a break to occur in any of the circuits-say at X in the line 0 c--the current is immediately broken, and notice is given at the central otlice by the stroke of the gong 15 and the starting of the register 16, precisely as if the first break of a signal had comein. The plugs 28 and 29 are simply moved over to connect the upper halves of the disks with the right-hand lower segments, and the double-lever switch 19 is thrown over from its normal position (shown in dotted lines, Fig. 4) to the position shown in heavy lines, Figs. 1 and 4.. This has the effect of throwing the relay 17 into circuit and ot' grounding the center of the battery 12 by wire 30, the transposition of the plugs 28 29 having changed the main circuit from battery 11 to extra battery 12. Each of the relays 17 18 is provided with three disks, 32 33 34. The disks 34 are connected together and with the wire 9 from one pole of the local battery, the armatures 35 being connected with the wire 9 to the other pole of the same battery. The disks 32 are connected with the insulated contact pins 36 of the relays, and

the disks 33 are connected with the metallic frames sustaining the pins 36. Each relay has a plug, 31, to fit between the disks and set up electric connection. with reference to the disks 32, 33, and 34 determines the action of the relay, making it work on either theforward or backward stroke, as may be necessary in the eventot' the grounding of the wire in case of a break.

The object of grounding the center of the battery 12 and of locating a relay on each side of it is to guard against the contingency, in the event of a break of the line, of a permanent ground being thrown on at one end, as is very 8o liable to occur should the broken wire fall on a lightning-rod or into the street. In the latter case the grounding is liable to be due to contact of the wire with street-car rails, a lamp-post, or awningsupport. should both ends be grounded, the circuit would be unimpaired; but this is most unlikely to occur.

The break is supposed to occur at X, and neither end of the wire grounds. tor in the central offioe turns the switch 19 and moves the plugs 28 29, as before described, and removes the pin 31 of the relay 18 from its normal'position between the disks 32 and 34, and inserts it between 31 and 33, as shown. has the effect to establish connection as follows: From the ground--say at the right of the break-the current passes through the wires 0' 1 to relay18, to battery12, thence through wire 30 to switch 19, and to ground G. From a box 100 to the left of the break the current traverses' the wires 0 2, relay 17, to battery 12,to wire 30, and to ground G. Now suppose a break at X, and the end of the wire to the left grounds on a lightning-rod or otherwise, the current to the 105 right of the break traverses the course above stated, but to the left acontinuous ground-cireuitis supposed to have been set up. The pin 31 on relay 17 is simply moved to the hole between the disks 34 and 32, causing the relay no to work on the backward stroke as before the break. The insertion of the pin between the disks 34 and 32 has the effect to establish the circuit from the wires 9 to the armature, and

thence through thecontact-screw 36 to the disk 1 r 5 32, so that circuit is closed as the armature flies back, whereas when the pin is between the disks 34 and 33 the circuit is set up on the forward stroke through the armature-post and the other screw. Of course in case ofa ground to 120 the right of the break at X the same transposition of the pin on the relay 18 is made. Should both ends ground, no movement of the pins is necessary, as the line is then practically intact. The gong sounds a single stroke 1 25 posed case a break at X and an accidental 1 o grounding of the end at the left of the break. The current passes through the wire 0 to the The position-of theplugs Obviously,

The opera- 0 This the usual and well-known form.

upper half of the disk, through the plug 29, which has previously been moved to theright,

to the right-hand lower half of the disk,

through wire 2 to extra relay 17, thence by the other wire 2 to the battery 12, by the wire 30 toswiteh 19 and to the ground. The closing of the circuit has the effect to bring the armature of the relay 1? against the contact-pin above the magnets, closing the circuit as foll0ws,viz: through the armature, wires 9 S,t0 battery 22, thence by wires 8 and 10 to disk 34, thence through plug 31, to disk 33, to post, which holds the pin against which the armature rests. As a result, the gong 20 gives one stroke and the register 21 starts running. The plug 31 is immediately moved to the hole between the disks 34 and 32, breaking the local circuit. As any box to the left of the break is now operated its circuitcloser makes and breaks circuit on the disk, the breaking of the circuit as it passes between the teeth allowing the armature on therelay 17 to fly back against the contact-pin 36. As it touches the pin, local circuitis set up as follows: through the armature,\vires 9 S, to battery 22, thence bywires S and 10 to disk 34, by pin 31 (which is now between 34 and 32) to 32, and thence to contact-screw 36. There are therefore three supposable cases in the event of a break in the line, namely: a dead-break and the grounding of either end, for we may lose sight of the possibility of both ends grounding at once. Until the break is repaired or the pins 31 are properly placed, the register continues to run. In the event of a dead-break, the pin of relay 18 is lowered. Should the left end of' the line ground, the pin in relay 17 is raised to the upper hole and that in 18 moved as before; and should the right end ground, the pins are undisturbed from their normal positions, only the switch 19 and plugs 28 29 being moved. A minutes experimenting with the pins 31 determines the case in point, for there are but three possible arrangements of the pins to meet anypossible case. In the eventof abreak in either of the circuits, to a or b b, the plugs 26 and 27 are simply moved to the right, so as to set up connection between the upper half and rightlower segments of their disks.

As above stated, the ground-connections of the various boxes are normally off, but provision is made for making and breaking circuit with the ground as the signal-box is operated. In Figs. 2 and 3 of the drawings is shown the box mechanism for this purpose.

H is the base of the box, having the usual frame, It, train of clock-work, escape-wheel, crank I, and stop j. It is furnished also with clamps L L for the main-line wire, one end being soldered to the frame h, the other being attached to a lip, 7r, on the insulating-block K. The lip k bears on the periphery of a disk, J, having notches to break and make circuit, whereby, when the disk revolves, the signal is transmitted. So far as described the box is of I add thereto v office.

a grouml-conuection from the clamp L, and connect the latter with a second lip,lr, on the block K, adapted to make and break circuit with a second disk, J, soldered to the face 'of the disk J, and concentric therewith. The disk J is smaller than the disk J, and the lip does not touch its periphery. The disk, however, is provided with a number of properlyspaccd teeth, j, which project far enough to touch the lip k as the disk revolves. and make circuit. In operation as the crank is turned the arm i passes clear of the pin j and the disks turn, sending the signal to the central As long as the line is intact the signals aretransmittedthereby. Thegroundisthrown on at the box, but not at the central office. In case of a break in the line at either side, the operator throws on the ground at the office, and the current, entering the box by the unbroken wire'eonnection, returns through the ground as the box is operated.

The advantages of my system over those heretofore in use are apparent. The line may break; but it is in the power of the operator at the central office to practic illy repair it instantly without leaving the office. Furthermore, my invention requires no revolution in the construction of existing lines in order to apply'it. The plant is not disturbed at all, the only change being one ofaddition, and that a simple and inexpensive one.

I have described myinvention as applied to district-telegraph purposes; but it is obviously equally applicable to fire-alarm telegraphs, hotel-annunciators, or other instances of a central office in communication with a number of stations and circuits.

I am aware that it is not new to ground the several stations of such systems, as well as the central office-as, for instance, in the non-interfering fire-telegraph system-in which case each box in being operated shortcircuits through the ground to the office and cuts out the boxes beyond; but that has nothing in common with myinvention except a groundcircuit, which is very old. A break in the wire of such a system cuts out the boxes beyond the break, and they remain inoperative until the break is repaired, whereas by my invention a break is instantly remediable at the central office, and all the signals come in as if there were no break, and every possible contingency in the event of a break is provided for. This result I believe to have been hitherto unattained; and

I therefore claim as myinvention and desire to secure by Letters Patent- 1. In a district or analogous telegraph system, a continuous metallic circuit connecting the several stations with the central office, a battery adapted to be grounded in the center, and a switch for shunting said battery into circuit, in combination with a relay intermediate each pole of said battery and the termini of the circuit, said relays working a local circuit register and gong, and having means for changing their stroke from forward to backward, whereby,in the event of the breaking of the main line, the contingency of the ground ing of either end of the line is provided for, as and for the purpose setforth.

2. In combination with the conventional district-telegraph plant, a normally-open groundconnection for each box, and means for closing such connection, a central otlice having a ground connection from an extra battery, arranged to be shunted into circuit, and having a register and gone, and relays 17 18, having means for reversing their stroke, and the switch 19, as set forth.

3. In combination with the mainline wires of the closed metallic circuit, the extra battery 12, having ground-wire 30, and the relays l7 and 18, having disks 32 33 34, plugs 31, and connections from said disks with the local battery, and the insulated pins and frame of the relays, as set forth, whereby provision is made for every possible contingency in the event of a break in theline with respect to the grounding of either end.

4. In combination with the main line and battery 12, the relays 17 18, on opposite sides of the battery, the double-lever switch 19, having ground 30 from the center of the battery, the relays 17 18, and wires 37 38, as set forth.

5. The box mechanism herein deseribed,consisting' of the notched disk J and smaller toothed disk J, concentric therewith, lips It It, and main line and ground connections, as set forth.



It. 1). \VILLtAMs, W. A. BER'LRAM.

It is hereby certified that in Letters Patent No. 253,080, granted January 31, 1882, to Chauncey F, McCulloh, of Baltimore, Md, for an improvement in District Telegraph Systems, the Word break, in line 64, on page 1 of the printed specification attached to and forming a part of said'Letters Patent was erroneously printed brake, that the proper corrections have been made in the files and records pertaining to the case in the Patent Office, and are hereby made in said Letters Patent.

Signed, countersigned, and sealed this 7th day of February, A. D. 1882.


[SEAL] Acting Secretary of the Interior.

Gountcrsigned E. M. MARBLE,

Commissioner of Patents.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4068105 *May 28, 1976Jan 10, 1978American District Telegraph CompanyCentral station system transmission apparatus
Cooperative ClassificationG08B25/045