US330465A - System of electric lighting - Google Patents

Description

(No Model.) 3 Sheets-Sheet 1.

H. P. BROWN.

SYSTEM 0E ELECTRIC LIGHTING.

No. 330,465. I Patented Nov. 17, 1885. Fl' .1.

@a 6%: Jl c# Wijzen@ en M' I3 I N. PETERS, Plwwmmmpmr. wmqlcm. n. c.

(No Model.) 3 Sheets-Sheet 2.

H. P. BROWN.

SYSTEM 0F BLEGTRIG LIGHTING. No. 330,465. Patented Nov. 17, 1885.

N. PETERS. Phom-Lilhngrzpber. wnshmgwn. D. C.

(No Modl.) 3 Sheets-Sheet 3. H. P. BROWN.

SYSTEM 0F BLBGTRIG LIGHTING. No. 330,465. Patented Nov. 17.1885.

Fly/l.

N. PETERS. Phmmunmgraphr. wnshingmn, D. C.

UNITED STATES PATENT OFFICE.

HAROLD I?. BROWN, OF CHICAGO, ILLINOIS.

SYSTEM OF ELECTRIC LIGHTING.

QPECIIEICATION forming part of Letters Patent No.330,165, dated November 17, 18235.

Application tiled June 8, 1885. Serial Nc.167,952. (No modell To all whom t may concern:

Be it known that I, HAROLD I). BROWN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Electric Lighting, of which the following is a specification.

This invention relates to the art of operating groups of incandescent lamps from an arc-light or high-tension circuit by means of an automatically variable resistance shunt around each group of incandescent lamps; and it relates more particularly to certain improvements in the apparatus or mechanism for automatically varying and controlling the resistance of the shunt-circuit.

In the accompanying drawings, which form a part of this specification, and in which similar letters of reference indicate like parts, Figure l is a front elevation of a device embodying my invention. Fig. 2 is a section on line 2 2 of Fig. l. Figs. 3 and 4 are vertical sections on lines 3 3 and 4 4 of Fig. l. Fig. 5 is a detail side elevation of the grooved slide attached to the movable core of the solenoid, and by means of which the contactpieces that vary the resistance of the shunt are moved in and out of the mercury-contact. Fig. 6 is a central longitudinal section of the dash-pot. Figs. 7, 8, 9, and I0 are detail views of parts, hereinafter to be explained; and Fig. 1I is a diagram view showing the arrangement of circuits. Fig. 12 shows a modification.

In said drawings, A represents the main or arc light circuit; B, the local or incandescent lamp circuit, in which are included, on suitable branch wires, b, the incandescent lamps b in multiple arc; and C is the shuntcircuit around the group of incandescent lamps, and in which is included the variable resistance c.

As shown in the diagram view, the shunt and lamp circuits diverge at a point, as x, and reunite at a point, as x.

D is an electro-magnet or relay having a fine-wire or high-resistance coil, D', which is included in the lamp-circuit on a branch wire, b, like one of the lamps. This relay has two armatures, d and d', attached to the two switchlevers cl2 and cl3, respectively, the function of which is to open and close the two short circuits E and F around the two coils 'E' and F of the double solenoid G. The coils E and F are both included in the main circuit; but they both remain normally short-circuited. The short circuit E diverges from the main circuit at a point, as mi, and reunites at x3, and the short circuit F leads from a point, as x, and reunites at a point, as x5. lVhen, by reason of the eXtinguishment of one or more lamps in the group, or other cause, too great a portion of the current is passing through the lamp-circuit, the armature d will be attracted by the magnet D, thus moving the switch-lever d3 and opening the short circuit F, so that the main current will be forced to pass through the coil F of the solenoid, and thereby pull its movable core G to the left, and thus diminish the resistance of thc shunt circuit until only the proper amount of current will pass through the lamp-circuit, the function of the solenoid G being to operate the contact maker or mechanism which changes the resistance of the shunt; and when, on the other hand, the current on the lampcircuitfalls below its proper amount, the short circuit E is in like manner broken, and the current forced to pass through the coil E', thereby pulling the movable core G to the left and increasing the resistance of the shunt until the current again properly divides between the lamp and shunt circuits, when the armature d of the relay D will again assume its normal position, thus re-esta-blishing the short circuit E and cutting out the coil E.

rIhe general arrangement of circuits which I have above briefly described constitutes the subject-matter of a previous application iiled by me under date of December 19, 1884, and numbered 150,737, and the same is therefore not herein claimed.

The present improvement consists, in connection with such or an equivalent system of circuits, in the combination, with the movable core or armature of the solenoid or electromotive device for operating the resistancechanging mechanism, of a dash-pot or other equivalent device to prevent sudden or irregular movements of said core and the consequent excessive and irregular changes in the resistance of the shunt.

It also consists, in connection with a series of movable contacts connected with different parts of the variable resistance, of a mercury- IOO contact covered with glycerine or some hydrocarbon to diminish as much as possible the friction in making and breaking the connections, and at the same time secure a perfect contact and prevent sparking as the connections are made or broken.

It also consists in employinga grooved slide or cani attached to the movable core of the solenoid for moving the contact-pieces in and out of the mercury.

It also consists inthe peculiar construction of these contact-pieces and their arrangement or combination with said slide, whereby the friction of said contact pieces against the slide is maintained the same whether the centact-pieces are pressed into the mercury or raised out of it, cr part in and part out.

It also consists in combining with the relayarmature levers a weighted line for retracting the same, instead ofthe usual spring, in order to prevent failure or inaccuracy in the operation of the apparatus, owing to the springs getting out of adjustment by changes in te1nperature or other causes.

It also consists in the novel devices and combinations ot' devices hereinafter more particularly pointed ont in the claims.

II represents the frame or case, preferably made of cast-iron, in or upon which the various parts are mounted. rlhe double solenoid G is secured to this frame at each end by suitable screws, It.

K is the mercury vessel or trough, extending between the two spools of the solenoid, and provided at each end with iianges k, by which it is screwed to the inside spool-heads of the solenoid. rIlhis trough is preferably made of cast-iron, and it is partially filled with mercury 7c', which is covered with glycerine k".

L is the grooved slide or cam, by means of which the movable contactpieccs N are made to make and break connection with the mercury in the vessel K. This slide is rigidly attached to and carried by an arm, L', which is securely bolted to the sliding core G ofthe solenoid, so that the slide will be carried back and forth with said core. The upwardly-bent end Z ofthe arm L carries on a suitable pin or trunnion, Z, a friction-wheel, Z2, which travels back and forth on the tracks or fianges k3 on the outerfaceofthemercury-troughK. The movable contact-pieces N preferably consist of wires inserted through suitable holesin the insulation block or plate N, by which they are supported. The wires N all extend in the same plane, and they are bent or folded near their outer ends to form the knees or projections n, which lit in the groove Z3 ofthe slide L. The eX- treme ends n of the wires N are again bent to project downward into the mercury-cup. lThe contact-pieces N should be made of springwire, and they should be flattened or thinned near the block N, as shown at a, so that they may be easily depressed into or raised out of the mercury by movement of the grooved slide L. The slide L should be so arranged in relation to the wires N that its middle line SOAGS will lie in the same plane as the wires N, so that each of said wires, when depressed into t ie mercury, will press against the upper wall of nthe groove Z with the same force as it presses against the lower wall of said groove when it is raised out of the mercury. In this way the degree of friction of the contact-pieces N on the grooved slide is rendered almost constant whatever theposition of the slide. The length of the slide L is about twice the space occupied by the series of contactpieces N, so that all of said contacts may be either raised or depressed at once if necessary.

The variable resistance c preferably consists of ilat carbon blocks c, contained in the pans c, lined with the insulating plates or strips c", which may preferably be of slate, metal pla-tes cL being inserted at suit-able intervals between the carbon blocks, with which metal plates the contact-pieces N are connected. It is obvious that when all the contact-'pieces N exA cept the right hand one are raised out of the mercury, the shunt-circuit current will be forced to pass through the whole of the resistance c,- but when the slide L is moved to the left and all the contact-pieces N are in connection with the mercury, the shunt-circuit current will take the left-hand wire N and therefore only pass through a small portion ofthe resistance c. When the resistance of the shunt-circuit is slight, it will be understood that the greater portion of the main current will pass through the shunt, and to prevent the resistance from being too much heated I make the carbon blocks c in the first part of the series of about twice the area of those in the subsequent or latter part, and for this reason also I place the first carbonpan above the others, so that the heat from the former will not be eonnminicated to the latter rlhe carbon blocks in the lower pans do not need to be so large as in the upper one, because when the current passes through the lower pile it is then only a small fraction of the total or main current, owing to the greater resistance in the shunt. By this disposition ofthe carbon blocks I am enabled to make a considerable saving in the aggregate amount oi' material required. The pans c, which contain the carbon blocks, are best made of thin sheet-iron, and they may be conveniently supported on shelves or projections h, secured to or east upon the box H.

M is the dash-pet pivoted at its lower end to a bracket, t, on the frame, and having its piston-rod M pivoted to the arm L, which is secured to the movable core of the solenoid. The piston-rod has a threaded end, m, by which it is secured to the piston mf, and the duct ml2 communicates with the threaded hole in the piston, so that by screwing the pistonstem in or out the size of the duct may be Varied andthe motion of the solenoidcore G thus adjusted and regulated as may be desired. As the piston is round and tits easily in the dash-pot, in order to hold it from turning when the piston-stem is to be screwed in or IOO IIO

out, I provide a little pin or lug, m3, on the piston, which engages in a corresponding cavity, m4, in the head of the dash-pot. To make this adjustment it will be understood that the piston-stem is to be first uncoupled from the arm L.

In lieu of the dash-pot other equivalent or substitute motion-regulating devices may be used in this combination, with the core of the solenoid and the contact making and breaking device operated thereby. The switchlevers d2 d3, operated by the relay-magnet D, are both bent levers, and their horizontal arms are each provided with vertically-adjustable contact-pieces or screws d4 d5, which make connection with the mercury in the cupsv d di. The switch-levers cl2 d3, in order to prevent friction, are connected by their iiat iiexible 'springs d8 di with the base-block d10, which is preferably of wood. The switch or armature levers d2 dii are retracted by means of weighted lines d d, which are connected at one end to said levers and at the otherto eyes or hooks d d14 on the frame. The weights for these lines are preferably made in two screw-threaded or extensible parts, du d1, so that by screwing or unscrewing said parts the line may be shortened or lengthened and its retracting force thus adjusted.

Inforderto guard against injury to the apparatus and lamps, Iinclude in the circuit an electro-magnet, O, having a pivoted armaturelever, o, provided with a catch, o', the function of which is to hold up the contact-piece P and break the short circuit P' whenever the lamps are in use, land to release said contactpiece and close said short circuit whenever the current through the coil of the magnet O ceases. The lever o will swing back by its own gravity when the current through the magnet O ceases, as it is pivoted to one side of its central line. When the current is again turned on or starts up, it is obvious that both the lamps and the resistance in the shunt will be cut out or shert-circuited until the contactpiece P is again raised out of the mercury. This of course could be done in various waysas, for example, by connecting the switch P with the armature of the magnet O, or by connecting it with the switch by which the group or building is connected with the main circuit; but it is desirable that the resistance-changing mechanism should be putthrough its movement before the short circuit P is broken and the current reaches the lamps, in order that the resistance of the shunt may be rst reduced to its minimum or to a small amount, so that if only one or two lamps should at the instant happen to be turned on no injury would result,and so that also the resistance-changing mechanism may be, so to speak, tested and found capable of performing its work before the current reaches the lamps. For these reasons I operate the switch or contact piece P by means of a groove or cam, p, on the slide L, the incline or rise of said cam being located near the right-hand end of the slide, so that it will not operate to raise said contact-piece P out of the mercury until said slide reaches the extreme limit of its throw to the left, and the resistance of the shunt thus reduced to its minimum. The relay-magnet D is provided with a coarse-wire or low-resistance coil, D2, which is included in the short circuit P, so that the current on this short circuit will energize the magnet D and pull the armature or switch lever dyand break theshort circuit F, and thus cause the current to iiow through the left-hand coil, F, of the double solenoid and pull the slide L to the left, as before described. The moment this is done the contact-piece P will be raised out of the mercury and the short circuit P broken, when the current will then pass through the shunt and lamp circuits. As the resistance of the shunt is at its minimum at this moment of beginning, if two or more lamps happen to be turned on in the group the slide L will almost instantly begin to move to the right, and continue so to do until the resistance of the shunt is so increased as to properly divide the current between the lamps and shunt.

To guard against injury to the lamps or apparat-us in case the core G ofthe double solenoid should stick or for any cause the apparatus should fail to perform its functions, I provide means for cutting out or short-circuiting the lamps whenever the current on the lamp-circuit and through the fine-wire coil D of the relay D may happen to increase to a certain prescribed limit above its normal or proper amount. This may be conveniently done by providing the relay D with a secondary armature-lever, R, pivoted to a bracket or post, ht, secured to the frame, and which,when attracted by an increase of current in themagnet, operates to swing` orpull the catch o to one side and allow the contact-piece P to drop into the mercury, and thus close the short-circuit P. The armature-lever R is provided with a threaded arm, i', and adjustable weight o", by means of which said armature-lever is retracted and so held until the current on the coil D of the magnet D for some cause reachesaeertain fixed extent aboveits proper amount. Ordinarily the armature-lever R should be so adjusted as not to be pulled up or operated until two or three lamps in the group have been extinguished without causing any change in the resistance of the shunt through some failure of the apparatus to perform its functions properly. Rt is an extension of the core of the relay D, preferably consisting of a soft-iron screw for convenience of operating thearmature-lever R. The catch 0 is made thin at ot, so that it may spring to one side under action of the armature-lever R, and the contact-piece P is provided with a shoulder or projection, p2, which rests upon the catch o. To p revcnt the contact-piece P moving laterally under action of the lever It, I eX- tend the head o3 of l[he magnet O down, and provide it with aslot, 0*, in which the contact P can move up and down, but not laterally.

In Fig. 12 I have shown what I deem abetter IOO IIC

IZO

and more improved form of device for releasing the contact-piece P when the current through the line-wire coil D' of the magnet Dbecomes too strong through failure of the mechanism to operate properly or other cause. This improved device consists simply in mounting the stop orjam-nut and screw d, which limits the movement of the armature-lever d upon the end of the lever-R, so that the increased pull of the magnet D on the lever cl3 will operate the lever B, and, further, in providing the lever R with a contact-piece, r2, which,when said lever R is raised, closes a short circuit, Q., between the two spring-contacts q q', thus cutting out the coil of the magnet O, so that its armaturelever 0 Will drop away, and thus release the contact-piece I?.

Q' represents a block of fiber or other insulation, upon which the lever B and the contact-pieces q q' are secured. It will of course be understood that the different parts are properly insulated 'from each other wherenecessary. As this is well understood by those skilled in the art, I have not thought it necessary nor endeavored to point out with particularity the insulating material. Some parts, such as the slide L, the blocks which support the wires N, &e., are most conveniently made of insulating material, like gelatinized fiber, for example. Ihe spools or frame G of the double solenoid may of course be formed of insulating material; but I iind that, owing to the heat and other causes, more satisfaetory results are produced by making them of cast brass or metal, in which ease, of course, these should be insulated from the frame H by rubber bushings and Washers around the screws 71., and also from the metal mercuryvessel K.

As shown in Fig. Il, the main circuit A leads from the right-hand binding-post to the heliXE' ofthe double solenoid,thenee from the point .ft-3 along the wire A to the other coil, F', of the double solenoid, and thence from the point along the wire A, through the lowresistance coil ofthe magnet O to the point a0, where the lamp-circuit B and the variable-resistance shunt C diverge. The lamp-circuit B leads from the point x to the left-hand bindingpost B', thence along the several branch Wires b, through the lamps b' to the right-hand wire B and binding-post B', and thence along the Wire B to the mercury-trough K, where it reunites, as at fr', with the shuntcircuit C. One of the branch wires b leads from the lefthand bindingpost B', through the inner or line-wire coil D' of the relay-magnet D to the right-hand binding-post B'. The variableresistance shunt G extends from the point through a greater or less portion of the resistance c, and thence through one of the movable contact-pieces N to the mercury in the niercury-eup, where the shunt-circuit reunites with the lamp-circuit, andthe reunited circuit then passes to the left-hand binding-post, A',

double solenoid, leads from a point, as w?, to the mercury-cup do, thence through movable contact-piece or switch-lever d2 and wire E back tothe main circuit at a point, as as. The short circuit F leads from a point, as fr, on the main circuit to switch-lever d, thence to mercury-cup di, and back to the main circuit at a point, as rlhe short circuit P', which serves to cut out both the lamps and the variable resistance in case of a failure of the apparatus to act, extends from a point, as fr, on the relay branch wire b, through the coarsewire or lowresistance coil DZ of the relaymagnet D, and thence through the movable contactpiece P `to the mercury-cup K and the main circuit A.

A' A' represent the main-circuit bindingposts, and B' B' the local binding-posts. The levers d2 and d3 form part of the short circuits E and F. Equivalent devices may of course be used for the dash-pot in its combination with the movable core of the solenoid to regulate the motion thereof. I should, perhaps, also state that my experiments and experience have shown that fly-wheel mechanism does not produce very satisfactory results, owing to the inertia making the resistance-changing mechanism too slow to start and difficult to stop at the right point, and that friction-brake mechanism I have found difficult to keep uniform in its action, and specially liable to stick and cause the core ofthe solenoid to start very hard. The dash-pot, I have found, produces the best results; but I of course do not limit myself thereto, as other equivalent or substitute devices may be used in its place in the combination. I have also discovered that in the use of the mercury contact with the movable contact pieces or wires N, if the contact piece or wire N has a square end, when it is being withdrawn from theinercur y a globule of mercury will follow up the wire, or, rather, form on its end above the surface of the mercury, thus producing irregularity in the making and breaking ofthe connections. To prevent this I provide the contact-pieces N, I), d, and l5 with pointed or sharp ends. By this means I am enabled to withdraw the contact-pieces from the mercury without causing any drop or portion of the mercury to rise above the surface thereof, and thus continue the electrical connection after it should be broken.

It will be observed that in the drawings, Fig. 11, I have only indicated three lamps of the group. f he apparatus shown is specially designed for operating twelve lamps in the group. It may, however, operate any number of lamps up to twenty-four by making some slight changes in the relative position of the metal plates c" in the resistance c. It is preferable, however, to have about twice as many divisions in the variable resistance as there are lamps inthe group, so as to have means of compensating for variations in the resistance of the carbon blocks due to changes in the temperature. The carbon pile or blocks may IOC) IOS

preferably be made o'f the pulverized residue from the distillation of coal. They are commonly known on the market as carbon battery-plates.

I claim- 1. The combination, with a main circuit, of a local or incandescent lamp circuit having included therein on suitable branch wires a number of incandescent lamps in multiple arc, a shunt around said lamps having therein avariable resistance, a relay, an electro-motive device set in operation by said relay for varying the resistance of said shunt, and a dash-pot for regulating the movement of said leztro-motive device, substantially as speci- 2. The combination of a main circuit with a lamp circuit having included therein a number of incandescent lamps in multiple arc, a variable-resistance shunt around said lamps, a'double solenoid having a sliding core for varying the resistance of said shunt, a dashpot for regulating the movement of said core, and a relay to control the circuit through one or the other coil of said solenoid, as may be required, substantially as specified.

n 3. The combination, With a group or number of incandescent lamps in multiple arc, of a shunt around such group of lamps, a variable resistance in said shunt, a series of movable contact-pieces connected with different parts of said resistance, a mercury-contact, and an electro-motive device for moving` said contact-pieces in and out of the mercury to vary said resistance, substantially as specified.

4. The combination, with a variable-resistance shunt around a group of incandescent lamps, of a mercury-contact, a series of movable contacts leading to different parts of said variable resistance, and a slide having a cam or groove for moving said movable contacts in and out of the mercury, substantially as speciiied.

5. The combination of a variable-resistance shunt around a group of incandescent lamps with a mercury-contact, a series of movable contact-pieces, a slide having a cam or groove, and an electro-motive device for operating said slide, substantially as specilied.

6. The combination of a variable-resistance shunt around a group of incandescent lamps with a mercury-contact, a number of movable contact-pieces, a slide having a cam or groove, and a double solenoid having a movable core connected to said slide for operating the same, substantially as specified.

7. The combination of a variable-resistance shunt around a group of incandescent lamps with a mercury-contact, a number of movable contact-pieces, a slide having a cam or groove, a double solenoid having a movable core, and a dash-pot, substantially as speciiied.

8. The combination, with a variable-resistance shunt around a group of incandescent lamps, of a mercury-contact and a series of movable contact-pieces, N, consisting of wires lying in the same plane, each provided with a projecting knee or fold, u, and a depending end, n', substantially as specified.

9. The combination, with a variable-resistance shunt around a group of incandescent lamps, of a mercury-contact, a number of movable contact-pieces, N, a slide, L, having a groove or cam, Z3, a double solenoid having a sliding core, G', a dash-pot, and a frictionwheel, and a truck therefor, substantially as specified.

10. The combination, with a variable-resistance shunt around a group of incandescent lamps, of a mercury-contact vessel, K, provided With iianges or tracks 7c3, a number of movable contact-pieces, N, slide L, having groove Z3, double solenoid G, having sliding core G', arm L', connecting said core and slide, friction-wheel Z2, and dash-pot M, substantially as specified.

11. The combination, With a variable-resistance shunt around a group of incandescent lamps, of a fixed contact, a series of movable contact-pieces leading to diiierent parts of said resistance, a double solenoid having a movable core, and a slide having a cam or groove, substantially as specitied.

12. The combination, with a variable-resistance shunt around a group of incandescent lamps, of a double solenoid having a movable core, a dash-pot, aslide having acam or groove, and a number of movable contact-pieces operated thereby, substantially as specified.

13. The combination, With a variable-resistance shunt around a group of incandescent lamps, of a movable core of a solenoid, a grooved slide or cam, and a number of movable contact-pieces operated thereby, substantially as speciiied.

14. rlhe combination of a variable-resistance shunt around a group of incandescent lamps With a number of movable contactpieces, N,and a grooved slide, L, substantially as specified.

15. The combination, with a group of incandescent lamps in multiple arc, of a shunt around such group, having included therein a variable resistance, consisting of a carbon pile With metallic plates insertedv at intervals, said plates being connected with a series of contact-pieces, substantially as described.

16. The combination, with a group of incandescent lamps in multiple arc, of a shunt around such group, having included therein a series of carbon plates or blocks, c', and a series of contact-pieces connected with said series of carbon blocks at different points, substantially as specified.

17. The combination, with a group of incandescent lamps in multiple arc, of a shunt around such group, having included therein a series of carbon plates or blocks, c', and aserics of contact-pieces, as N, connected with said series of blocks at different points, the blocks in the first part of said series being of larger area than those in the latter part thereof, substantially as speciiied.

18. The combination, with a group of in- IOO 'around such group having a variable resistance included therein, a number of movable contact-pieces connected with different parts of said resistance, a mercury-contact, a slide having a groove or cani, a double solenoid having a movable core for operating said slide, a relay having two movable armatures, two contact-pieces opeiated thereby, and two inercury-coiitacts, substantially as specified.

19. The combination, with a variable-resistance shunt around a group oi" incandescent lamps, oi' a solenoid and mechanism operated thereby for varying said resistance, and a relay having two movable switch-levers and mercury-contacts, substantially as specied.

20. The combination, with a variable-resistance shunt around a group of incandescent lamps in multiple are, of a double solenoid and mechanism operated thereby for varying said resistance, and a relay having two movable switch or armature levers and weighted lines for retractingsaid levers, substantially as specified.

21. The combination, with a variable-resistance shunt around agronp of incandescent lamps in multiple are, of a double solenoid and mechanism operated thereby for varying the resistance of said shunt, and a relay having two armature-levers and carrying contactpoints, weighted lines for retracting said levers, and two mercury-contacts, substantially as specified.

22. rPhe combination,with a main circuit,of a local or lamp circuit having a number of incandescent lamps therein in multiple are, a variable-resistance shunt around said lamps, a double solenoid, the coils of which are normally sliort-eircuited for varying the resistance of said shunt, a relay to open and close the short circuits around the coils of said solenoid, a short circuit i'or cutting out both the lamps and the shunt-resistance, and means for closing said short circuit in case the current through the lamps and the relay increases a certain prescribed extent above its normal amount-as, for example, the extent due to the extinction of two oi'threelampswithout corresponding change being made in the resistance of the shunt, substantially as specified.

23. rlhe electric lighting system consisting in a main circuit, as A, a lamp-circuit, as B, incandescent lamps in multiple arc, as b", a shunt-circuit, as D, a variable resistance therein, as c, an electro-motive device for varying the resistance oi' said shunt, a relay to set said electro-1n otiv-e device in opcration,a short circuit, as P, and means for closing the same in case said resistance-varyi ng device lails to act, substantially as speciiied.

24. The electric lighting system consisting in a main circuit, as A, a lamp-circuit, as B, incandescent lamps, as b, in multiple arc, a shunt, as C, having included therein a variable resistance, as c, a double solenoid, as E F, short circuits, as E F, around the coils of said solenoid, a rela-y, as D, having a coil, as D', included in a branch, as Z), and having a second coil, as D3, included in a short circuit, as P, and an electro-magnet, as O, for holding said short circuit P" open, substantially as specified.

25. The combination, with a variable-resistance shunt around a group oi' incandescent lamps, of a series of contact-pieces, N, leading to different parts of said resistance, a contactpiece, P, for opening and closing a short circuit, as P', and a slide, L, having a cain or groove, Z, for operating said contact-pieces N, and also a cam, as p, i'or operating said contact-piece P, said eain p being so located or arranged in relation to said cani Z that the short circuit P will not be opened until the resistance oi' the shunt is reduced to its minimum, substantially as speciiied.

2G. The combination, with a variable-rcsistance shunt around a group of incandescent lamps, of an electro-motive device for varying the resistance of said shunt, a short circuit, P, and an electro-magnet for closing said short circuit in case said resistance-varying device fails to act, substantially as specified.

27. The combination, with a variable-rcsistanee shunt around a group oi' incandescent lamps, of an electro-motive device for varying the resistance of said shunt, a short circuit, as P, and an electro-magnet to close said short circuit in case the resistance-varying mechanism fails to act, and to'lieep the same closed until the resistance of the shunt is reduced to its minimum.

28. lThe combination, with a variable -resistance shunt around a group of incandescent lamps, of an electro-motive device for varying the resistance of said shunt, a short circuit, as P, an electro-magnet, D, for closing the same, having a coil, D', in circuit with the lamps, and a second coil, D2, included in said short circuit P', substantially as specified.

29. The combination, with a variable-resistance shunt around a group of incandescent lamps, of a mercury-contact, a number of movable eontact-pieces, N, a movable contactpiece, P, and a slide, L, provided with cams Z3 and p, substantially as speciiied.

.30. The combination of a mercury-contact with movable contact-pieces N, movable contact-piece P, and an electro-magnet, as O, to hold said contact P out of the mercury, substantially as specified.

3l. The combination of movable contactpiece P with electro-magnet O, having armature-lever o, provided with catch or shoulder o, electro-magnet D, and lever It, to release said contact-piece P, substantially as speciiied.

3a. The combination, with a double solenoid, of a relay-magnet, short circuits around the two coils of said solenoid, the movable core of said solenoid, and a dash-pot, siibstantially as specified.

33. The combination, with a variable resistance, a series of contact-pieces leading to different parts of said resistance, a double IIO solenoid having a movable core, a relay-magnet,'short circuits around the two coils of said solenoid, a dash-pot, and mechanism for operating said contact-pieces, substantially as specified.

34. The combination, with an electromagnet, of its movable armature, and a weighted line for retracting the same, said weight consisting of two extensible parts,whereby the same may be adjusted.

35. The combination, with a group of incan descent lamps in multiple arc, of a shunt around such group, having included therein a variable resistance having a greater number of parts or divisions than there are lamps in the group, substantially as specified.

36. The combination, with a group of incandescent lamps in multiple arc, of a variableresistance shunt around said group, an electro-motive device for varying the resistance of 2o HAROLD P. BROVN.

Vitnesses:

EDMUND ADoooK, JOHN W. MUNDAY.

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