US910184A - Railway signal system. - Google Patents

Description

C. E. DUFIIE.

RAILWAY SIGNAL SYSTEM.

rrLIoA'rIoN num AUG. 19.1907.

Patentgd Jam 19, 1909.

C. E. DUFPIE.

RAILWAY SIGNAL SYSTEM.

APPLIoATxo! rxLEn AUG. 19.19157.

C. E. DUFFIE.

RAILWAY SIGNAL SYSTEM.

PPLIOATION FILED AUG. 1s. 1901.

Patented Jan. 19, 1909.

C. E. DUFPIE.

RAILWAY SIGNAL SYSTEM.

nrmo'rlon FILED AUG. 19,1907.

Patented Jan. 19, 1909.

4 SHEETS-SHEET 4.

Fl j ru: Nonu Annu :o

CHARLES E. DUFFllQ, OF OMAHA, NEBRASKA.

RAILWAY SIG-IAL SYSTEM.

Specification o Letters Patent.

Patented Jan. 19, 1909.

Application filed August 19, 1937. Serial No. 389,187.

To all "ar/mm 'it may concern:

Be it known that l, CHARLES E. Duri-ua, residing at Omaha, in the county ot Douglas and State of Nebraska, have invented certain new and nsetul lnnprorements in Railway Signal tiysteins.y olf bieb the following is a description, reference being had to tbc aeconipanying drawings, 'forming a part ot this specification, in which correspon(ling letters ot' reference in the dillerent figures` indicate like parts.

Une 0i the obj ects of the present invention is the provision of an improved automatic electric railway signal system. v Another object of the. invention is the production ot' an electric signal system which shall give a danger signal upon the derangenient o'l any ot its parts.

The intention also relates to an electric signal system comprising signal circuits which are not grounded, in order that high VVoltage currents may be employed.

The invention further relates to a .signal system con'iprising signal circuits entirely independent of each other, any derangeinent all'ecting only the circuit in which it occurs.

The invention also relates to an electric signal system, in which there is no electric connection between the signal. circuits` proper and the track circuits.

The invention also reitersto a s l lal system in which the circuits l'roni whit i current is most likely to escape are comparatively short.

The inrention also refers to other improvements in signal systems and apparatus bereinafter forth.

In tbc accompanying drawings.y Figures 11 i! and i are iliagrains4 illustrating portions olJ a signal system embodying [ny invention. Fig. 't is a View illustrating the Wiriiagl of circuits of the signal system as arranged at switches. Fig. i3 is a diagram ot' the wiring for signal system to be used at railway stations.

In the embodiment herein shown of my invention, the signals are transmitted to the engineer along the riglitotway at station.`l which l shall denominate signal statil'nis l). E, it, G, H, etc., (stations l), E and l" only being shown in the drawings), said signal stations being preferably located approximately one halt niile apart. iie: Ween they :iig nal stations, preferably midway, are placed the batteries and relays which control the apparatus at the Various signal stations.

The points at which said batteries and relays are located I will indicate on the drawings by the letters d, c, and f, etc., and Will term battery stations. Theterrn train shall be used throughout to designate a steam or electric locomotive, a train or a single car.

rihe track between each two adjacent battery stations is divided into five insulated sections. The section directly opposite the signai station isppreferabl about 200 feet long, and is numbered 1 in t ie drawings. At each end ot' the section 1 is a shorter section 2, 8. The two track sections completing the distance between the battery stations are numbered 4 Upon each locomotive equi ped for service upon a railway provided Wit 1 this si aling system is placed apparatus adapte to be electrically connected at each of the signal stations along the road with a comparatively short circuit which shall be herein termed the contact. circuit. If Said Contact Circuit is closed and otherwise in operative conditionj the apparatus carried by the locomotive will not be a'liected, and no danger signal Will be given. if the contact circuit is open or deranged, the apparatus upon the locomotive will be operated to give a danger signal. Said contact circuit is arranged to be opened and closed by apparatus included in a signal circuit extending, in this instance, from said signal station to the third signal station ahead. Said signal circuit, in turn is arranged to be broken and closed b relays included in a number of circuits o which the track rails and the car Wheels and axles form a part. Said track circuits Will next be described.

llle rails 4 are connected at their left or west ends with a relay 6 by means of Wires T and H. the east ends of said rails being connected with a battery 9 by means of wires 10 and 11, the armature of a. relay 12 beii g included in said Wire 11. The relay Vconnor-tial with the rails 3 by means of ille wires 13 and 14. Said rails 3 are connected with a battery 15 by means of Wires !l' and 1T. The rails 1 are connected at their West ends with an electro-magnet 18 by wires it' and Upon the armature of the magnet is a locking projection 18a adapted to engafe the armature of the relay 12 and prevent said relay-armature from contacting its contact point.

The rails 1 are connected near their middle portion With a battery 2l. At their east ends the rails 1 are connected with an electromagnet 22 by means of Wires 23 and 24. The rails 2 are connected With a battery 25 by means of Wires 26 and 2T, and with a relay 28 by means of Wires 29 and 30. The West ends of rails are connected with a battery 31 by means of Wires 32 and 33, the wire 33 including the armature of the relay 2S. The east ends of rails 5 are connectedwith a relay 34 by means of Wires 35 and 36.

Fig. 4 illustrates the arrangement of the track circuits at switches, draw-bridges, etc., 3T, 38 and 39 being insulated rail sections, 40 a track battery, and 41 a relay for opening the signal circuits to be hereinafter inentioned. A wire 42 connects the rails 38 and 39, a circuit-breaker 43 being inserted in said Wire. The movable Contact 44 of the circuit-breaker is connected With the switch points so as to be moved to open or shut the track circuit when the switch is set for the siding. An open switch leading from the main line to the siding, therefore, Will cause a danger signal to be given to an approaching train as will appear hereinafter. Fig. 4 also illustrates the means for giving a danger signal in case a car be left standing on a. siding in such a position that a passing train cannot clear it. The sections and 46 of the siding rails are insulated from the remainder of the siding and connected with the rails 3T and by means of the Wires 4T. It will be seen that a pair of Wheels resting upon the rails 45 and 4G Will short-circuit the battery 40 and cause the relay 41 to break the signal circuit. Said signal circuits will noW be described. At signal station D a relay 4S is connected with the common return Wire 49 and with a signal Wire 50 extending to signal station A (not shown), a

relay similar to relay 4S being there connected in series with said signal Wire 50 and the common return Wire 49. Atthe signal station D another relay 51 is connected in series with the connnon return Wire 49 and a signal Wire 52 running eastward to signal station G (not shown), a similar relay being there connected in series with said signal Wire and the common return Wire. Similarly, at signal station E a relay is connected in series with the common return Wire 49 and a signal Wire 54 extending to signal station B. At signal station l) another rela 55 is connected in series with the common return Wire and a signal wire running eastward to signal station ll'. rit si al station F the relay 57 is connected with the return Wire 49 and a signal Wire 58, extending to signal station C, and a relay 59 is connected with the common return Wire and a signal Wire 60 extending eastward to signal station l. The Contact points 61 of the relays 48, 51, 53, 55, 57 and 59 are Connected with the common return Wire 49 l the relay points of said relay open.

by means oi' the Wires G2. The arnialures of the relays 4S and 51 are electrically connected through the Wire G3, are also the armatures of relays 53 and 55, and 5T and 59. Midway between the said armatures and connected between the wire G23 and the connnon return wire il) is a relay G4 and ay battery 65. it will be seen that when either oi the relays 4S and 5l is energized a circuit will be closed through the relay (34 and the battery G5.

ln each oit' the signal Wires a0, 52, 54, 5b, 58 and G() is placed a inain battery GG connected in parallel with the common return wire 49, said batteries being located at the baltery stations. At opposite sides of said battery, relays (5T and (3S are included iu said signal wire, the contact poinls ot' said relays being (.:onnectcd with said signal Wire and the coinniou return wire by means oi wires 55) and 70. lilach of the signal Wires 50, 52, 54, 5G, 58 and G0 is connected with the arinatur-s ot the relays G and 54, the springs of said relays tending to move said armatures in the direction to open said Wires.

I will next describe the coni act circuit at each oi the signal stations. At each signal station there is placed along the track at a short distance outside of the traliic rails tivo contact rails T1 and 72, preferably oi inverted V-shape in cross-section. These contact rails are arranged lo bc contacted by suilable brushes, shoes or similar devices carried by the loconio ive, said brushes being connected With cab allipaiatus (not herein described) for noting the condition of the signal apparatus for the purpose of obtaining a signal. The contact rail T1 is connected with the armature ot' the relay -l by nieans of the Wire T3. The contact rail T2 is connected with the contact point of said relay by 11u-ans of the Wire 74. The apparatus earried by the locomotive may bc of any suitable charaeter, adapted to be aliiected by the condition olf the contact circuit. Such apparatus is indicated diagrannnaticaliy at (Figs. 1 and lith certain furnis of eab apparatus it may be desirable to include a resistance T5 in the wire 74.

ln Figs. 1, 2 and 3 are shown successive portions of a signal system en'il'iodying my invention, the live circuits being indicated by heavy lines and the dead circuits by light lines. The track circuits are .shown in normal condition in Fig. 2. Vtails 4 are i11- cluded in 'lhe circuit c 'oniprising the relay (i, battery f and the relay point oi the relay l2. The relay l2 is in circuit with the rails i3 and the battery 15. The Western ends ot the rails 1 are connected with the electro-magnet 1S, the armature of which carries the locking projection 1S adapted to engage with the armature ot' the relay l2 for holding It Will be seen that so long as the rails 4 are electrically continuous and unoccupied by a pair ot wheels the relay G will be energized by thc current from battery 9 and will attract its three armatures, closing the points of said relayv as shownin Fig. Q, and making the sig- nal Wires 54 and 58 electrically continuons. But the relay G Will not be cnernirfzcd unless the relay pointes otI the relay 12 are closed so as to complete the circuit ot thc battery Sl. Said points will be closed so long' as tbc circuit is completed troni the battery 15 through the rails l unless while tbc armature ot' the relay 12 is in its uppermost position, tbc magnet 18 deprived of current, in which case the, locking projection 1H upon the armature of said magnet will engage tbc armature ot tbe relay 1Q, and bold it open. The purpose ot tbie interlock will bc explained hereinafter. i\ssaniing' now that a mir ot wheels contactsthe rails 4, tbc electrical conditions just described will bc altered to those illustrated in Fig'. 1. The wbccls 1/ bare elmrt-circuited battery 9 and tbns deprived relay (l ot current. brcalting the signal wires 50, 54 and 5R. Said signal wires also would be opened by the presence oi a pair ot' Wheels across tbe rails 3, said wheels; slmrt-circuitingr the battery 15. tbns ileprivingil the relay 12 of current` and brcaltiirg,1 the circuit in which thc relay il is included. lt now, while there is a pair o'l Wheels across tbc raile 3, a second pair ot' wheels cncrs upon the rails 1, (as would occur in llae case ot a train traveling in tbe direction ot tbe arrow, Fig. 1), a short circuit will llc established through the pair ot wheels upon rails 1, deprivinp; the niagnet 1S ol current, whereupon its armature will bc released and the locking projection 1S will engage the arnntturr ot tbe relay lf2 which has previously receded. The circuit through battery 9 and tlic relay lf, cannet non' be again closed. even though tbc short circuit across the rails 4 be rcnioi'ed, so long as the magnet 1S is deprived ot' current. As soon as the short circuit is removed 'troni across the rails 1, the magnet 1S again receives current, and attrac inn' its arnmtnre, permits the armature olE tbe relay to close the circuit through thc relay lf3 and close the signal wires 50, 54 and ."-l torna-gb the arn'iature and relay points ot' said relay. But it will be seen that tlc train will not rcniovc said short-circuit lit-tore sbortcircnitingj the battery by entcringj anon tbc rails Q.

Precisely siinilar electrical conditions obtain to the right ot' any signal station upon the approach ot a train, but affecting. however, tbe relays QH and 34 and the magnet 2Q.

ll'aii'ingg.A now described the operation of the instrinncnts in the track circuits, the operation otl tbc signal circuits will next be explained. Referring to battery station e at battery station c and the relay points ofthe relays 6 and 34 at battery station d to the relay corresponding to relay 51 at the signal station C, thence to the common retnin wire and back to the battery G6 at battery AStation e. The remainder of the current from said battery flows east through the relay 68, the relay points of the relay 6 at battery station e, the relay points of relays 34 and G at battery station f through the relay 57 at signal station F, thence to coinmon return Wire 49 and back to battery 66 at battery station e. It will be seen that so long' as current is flowing in each direction t'roin said battery G6, the relay before retcrred to at the signal station C and the relay 57 at signal station F will both be energized and will attract their armatures, inaking` an electrical connection between said armatures and the Wires 62. It, however, the signal Wire 58 be open at any point between battery station e and the signal station C, the relay before referred to at said signal station and the relay G7 at battery station e will both be deprived of current. llf'hen the armature of the former relay drops, the circuit between said armature and its wire 62 will be opened. The dropping of tbe a rmatare of the relay 67 at battery station c will have the following effect. A circuit will be closed from the battery 66 through Wires 49 and 69, theiarmature of the relay (3T, wires 70 and 58, and relay 68. This will short-circuit the current from battery station e, and it can no longer How to the relay 57 at signal station F. The latter relay, thus deprived of current, will allow its armature to fall, and the Circuit will be broken between said armature and the Wire G2 leading to the common return wire 49. A break in the signal Wire 58 at a point east of the battery station e Wilhof course, have the saine effect. on the relays at signal stations F and C, except that in this event the sh0rtcircnit would be formed by the relay 68 and would occnr betweenthe battery station e and the signal station C. It will be observed. however, that when the current from the battery 66 at battery station c is short crcuitcd as first described, said current continues to How through the coils of the relay (38 at said battery station, because said shortcircnit is formed outside of the connections ot said relay. As soon, however, as the circuit is restored between the battery 66 at battery station e and the signal station C, the relay 67 will again be energized, and, attracting its armature, will remove the short-circuit between the battery 66 at bat- 1 tery station c and the signal station F, and current will again be iermitted to flow east to the relay 57 at said1 signal station F. It will now bey seen that a pair of wheels across the rails at any point between signal stations F and C will deprive ot current both the relay 5T and the relay corresponding to 5E) at signal station C, the first by an open circuit and the other by a short circuit, or the reverse. according to where the train stands on the track between said signal stations. The breaking of a track circuit at any point between the said two signal stations will have the same ellect, and this will happen not in one only, but in the three signal circuits, because each r lay (l and 34 governs three separate signal circuits. The resistance T5 is included in the contact circuit so that an accidentally or inaliciously formed short-circuit cutting out said resistance shall be detected by the cab apparatus. To render such detection certain the resistance 75 should be inserted as near as possible to the relay points of the relay Gt.

The magnets 1S and QQ are employed to prevent a misleading clear signal being given to a locomotive drawing no load. The rear wheels of such an engine, westbound, would have left the rails 2 betore the contact brushes touched the Contact rails Tl and T2.

This would allow the track Circuits 2 and 5 to close, closing the signal circuit extemjliug rearwardly of the engine, energizing relay 48, 5l, 53, 55, 5T or 55) in said circuit, clos'- ing a circuit through battery G5 and relay G4, and closing the Contact circuit. A clear signal would then be given, said signal coming from` the portion ot the train-control blck behind the engine, even it there were a train in theI portion of said blot-t: :head et the engine. lt is therefore necessary, for the protection of light engines, to keep the relay at the given signal station, in the rear wardly extending circuit, deprived ot current until the Contact brushes have passed oli" the Contact rails.

To prevent the giving ot a false danger signal by the train itseli at every signal station, the distance ot the rails 2 and 13 vfrom the contact rails Tl and T in the present embodiment of the invention, should be longer than the distance from the front truck of the longest engine which passes over the road to the rear wheels ot the tender, the preferred length being not less than 90 feet.

In order that there may be no points at which two trains could meet without getting signals, I arrange the signal circuits so that they overlap each other, as shown, one of the two signal circuits that end at each signal station extending to the third signal station ahead, and the other circuit running to the third station behind. The reason for two overlaps instead oli' but one is to provide against the remote possibility ol two approaching trains striking and leaving the contact rails at stations D and G, for eX- ample, before the one train reached the rails 2 (station D) or the other, the rails 3 (station Neither train having reached said track rails before the other lett the contact rails, neither would operate the trackcircuit apparatus to open the signal wire 52 in time to signal the other. The trains would then proceed to stations ll and F where they would he stopped, as the signal relays governing these two lstations would be deenergizccd before either train arrived.

lt will be seen that a train receives signals only from` the signal circuits extending forwardly from any particular signal station, but that it transmits signals to stations ahead ol and behind it. Any train, therefore, as it moves over the track is practically the center of a movable traiireontrol or signal block three miles long, which shifts forward, as the train progresses, every halt mile.

lt is evident that a single section of the signal system herein .shown may be employed for protecting the right-of-way for any snitable distance at each side of a railway sta tion, or the right-ot-way between two adjacent stations. ln Fig. l have illustrated diagrannnatically an isolated system eniployed to protect the track for, say, three thousand feet at each side of a railway station. The signal circuit ctnuprises the coininon return wire TG, the signal wire 7T, the central battery T8 connected in parallel between said common return and said signal wire, and the relaysv 79 and St), said relays being located at the signal stations Sl and VQ, respectively. VIt is desirable that the circuit extend about two thousand teet outside of the yard limits (not indicated) in order that trains may work treely within the yard,

and yet warning be given of their presenceI or ol open switches at a sntticicnt distance to allow an approaching train to stop. ln an isolated signal system, such as shown in Fig. 5, the track eircuita and the wiring for the relays at the signal stations are the same as in the system illustrated in Figs. l, i! and I3, and the mode ot operation the saine in both.

For convenience l have herein used the term battery to indicate any suitable source ot eleetrfal energy, and the terni relay l to (,lesiguate various equivalent forms ot apparatus.

It will be apparent to those skilled in the art that the circuits and apparatus herein shown may be altered and rearranged in various ways without departing from the spirit and scope ol myiinvention. No undue limitation, therefore, should be understood from the foregoing detailed description.

The contact circuit and the locomotive ap- 1f.liian electric signal system. in conilii- Iiatiniua plurality otncrniaily-closcr'l, tn'ci'- j lapping, independent s/igi'ial ciig'cnits;

titi.

paratusl licicin disclosed arc trlaiincd in n v (impending application Serial En. :50.590, tiled ikpriti", 190.1 l'

:L claiinias myi iii vention:

a noriiially-cluseil track circuit; and means in said tracklcii'ciiit 'for opening and closing all of said. signal circuits.

2. In ail/electric signal system; in cciiil'iination. aTsignal circuit; a track circuit controlling said siena] circuit; a track circuit controlling sait' first mentioned track circuit; and means for rendering ineffective the action ct tlic apparatus iii said second inenticncd track circuit.

3. ln an electric signal system, in combi nation. a signal circuit; a track circuit controlling szi'id signal circuit: a track circuit controlling said first mentioned track circuit; and a track circuit for rendering iiiclicctirc tlie acjiionni tlic apparatus in said second niciiz'ioned truck circuit.

4l. ln an electric signal system; in combination, a signai circuit; a track cir-cuit controlling said signal circuit; an electroniagnct for locking in inoperative position tlie appar-alusin said track circuit; and a track circuit in n'liicli said elcctroinagiict is ineluded.

5. lr. an electric signal system, in combi nation, a signal circuit; a track circuit controlling :said signal circuit; a track circuit. controlling said lirst mentioned track cir cuit.,` an elcctromagnet for locking in in operative position tlie apparatus in said sec ond mentioned track circuit and a track circuit iii uliicli said electroniagiiet is included.

G. In an electric Signal system; in combi natioii,signal means comprising a forwardly? extending signal circuit and a rearwardlyextending signal circuit; means operable by a train for opening said rearwardly-extending signal circuit; and means for transmitting a signal to said train from said forivardly-eXtending signal circuit.

7. In an electric signal system, in combination; a' forwardly-extending si nal circuit; a rearwardly-extending signa circuit a contact circuit; means for controlling said Contact, circuit; and means in eacli of said signal circuits cont-rolling said last inentioned means.

8. In an electric signal. system; iii combination, a forwardly-extending signal cir cuit comprising a relay; a rearwardly-extending signal circuit coinprisin a relay; a contact circuit and means contro led by said relays for controllin f saidcontact circuit.` `9. In an .elec/tric'sigiial system, in combination, a f owardlyf extending si nal circuit; a; rearwardlyextendi-ng slgna .,circuit;

contact-circuit; aait-cuit comprisingtil re,- lgysntrolling saidcqntact circult: and .a

iv i iiiflay nieacli ofsaid signal circuits controL s ling said las? Mentioned:- circuit.

r io.-u iii au electric signal systciii,`.in ccmt Func-juni; signal means comprising a for wf:ifdlycncnaing lsignal circuit and a rear- `ardlytxtcinliiig signal circuit; means oper- ;lc by a train tor opening said rearwardly- .fr\.zciniing signal circuit; and means carried .'f said train tor noting the condition of said torn-uidly-extending signal circuit.

ll. in au electric Sgnalsystein, in com- 1niuaiion, a signal circuit comprising a batter-j," connected in parallel in said circuit; means for opening said circuitat one side ot said battery; and means operated upon such opening of the circuit for denergizing tlie remainder of tlie circuit.

in an electric signal system; in combination. n signal circuit comprising a battery connected in parallel in said circuit; nicaV for opening said circuit at one side of iliciiaiteiy; and means operated upon such opening ot' tlie circuit for sliort-circiiiting the current :troni tlic remainder of said cir cuit. i

lli. in an electric signal system, in coin bination, a signal circuit comprising a battery connected in parallel in said circuit; i uis for opening said circuit at one side of a l baticrg. and a relay iii said side of tlie' circuit arranged to short-circuit tlie current from die otlicr side oi said circuit.

l-l. In an electric signal system; units conlsistiiig of two oppositely-extending si nal circuits; tiro track circuits each control ing cnc of said signal circuits; a contactcircuit.;

id means controlled by said signal circuits 'ir r ci'nitrollino said contact` circuit.

",515, In an electric signal system; in com- `inaticn, signal means; two track circuits c iitrolling said signal means; two track circuits eacli controlling one of said first mentioned track circuits; and a track circuit including means for rendering inetfective tlic action of tlie apparatus in the two last mentioned track circuits.

16. In an electric signal system; units coniprising a track circuit; a contact circuit comprising contact rails located centrally of said track circuit; signal means; `and a track circuit at each end of said first inentioned track circuit ,and controlling said signal means, said first mentioned track circuit including means for rendering ineffectivc tlie action of the apparatus in Said last mentioned track circuits.

17. Invan electric signal system, in c0mbination, signal means comprising a forJ Wardly-extending signal circuit and a rearwardly-exteiidiifig signal circuit; means for transmitting a signal to a trainfrom said circuits; and means cperable'by a train for preventing one of said circuits from trans i mittinva signal to a train. p

`18. fn an electric' signal system, in coinisc Correction in Letters Patent No. 910,184.

bination2 Ameans for transmitting a signal to a train; means located in front of said signal-transmitting means, for controlling said signal-transmitti means; means located in the rear of sai signal-transmitting means, for controlling said signal-transmitting means; a forWardly-extendi signal circuit in which the lirst mentions controlling means is included; and a rearwardl -extending signal circuit in which the second7 mentioned controlling means is included.

19. In an electric signal system, in com- [SEAL] nimma bination, a circuit comprsin a relay and a source of electrcalenergoth connected 15 in parallel in said circuit; a signal circuit arranged to jaect said circuit at one side of said relay; another signal circuit arranged to affect said circuit at 'the opposite side of said relay; and signal means controlled by 20 said relay.

CHARLES n DUFFIE.

Witnesses:

H. S. DANIEL, Maen C. HIGGINS.

It is hereby certified that in Letters Patent No'. 910,184, granted January 19, 1909, upon the application of Charles E. Due, of Omaha, Nebraska. for an improvement in Railway Signal Systems, an error appears in the printed specification requiring correction,4 as follows: In line 21, page 2v, the wordrfshut should read shunt; and that the said Letters Patent should be read with this correction therein that the same may conform to the recordof the case in thePatent Oice.

Signed and sealed this 9th day of February, A. D. 1909.

C. c. BILLINGS,

Acting Commissioner of Patents.

Correction in Letters Patent No. 910,184.

bination2 Ameans for transmitting a signal to a train; means located in front of said signal-transmitting means, for controlling said signal-transmitti means; means located in the rear of sai signal-transmitting means, for controlling said signal-transmitting means; a forWardly-extendi signal circuit in which the lirst mentions controlling means is included; and a rearwardl -extending signal circuit in which the second7 mentioned controlling means is included.

19. In an electric signal system, in com- [SEAL] nimma bination, a circuit comprsin a relay and a source of electrcalenergoth connected 15 in parallel in said circuit; a signal circuit arranged to jaect said circuit at one side of said relay; another signal circuit arranged to affect said circuit at 'the opposite side of said relay; and signal means controlled by 20 said relay.

CHARLES n DUFFIE.

Witnesses:

H. S. DANIEL, Maen C. HIGGINS.

It is hereby certified that in Letters Patent No'. 910,184, granted January 19, 1909, upon the application of Charles E. Due, of Omaha, Nebraska. for an improvement in Railway Signal Systems, an error appears in the printed specification requiring correction,4 as follows: In line 21, page 2v, the wordrfshut should read shunt; and that the said Letters Patent should be read with this correction therein that the same may conform to the recordof the case in thePatent Oice.

Signed and sealed this 9th day of February, A. D. 1909.

C. c. BILLINGS,

Acting Commissioner of Patents.

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