US678607A - Electric-arc lamp. - Google Patents

Description

No. 678,607. Panama my I6, lam. J. J. woon.

ELECTRIC ARC LAMP.

(Application led Dec. 14, 1900.) (No Model.) z sheets-shunt Patented'luly I6, IQOl.

(No Model.)

INVENTOR:

Til will UNITED STATES PATENT EETCE.

JAMEs .rr-woon, or FORT WAYNE, INDIANA.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 678,607, dated July 16, 1901.

-Application filed December 14,1900. Serial No. 39,888. (No model.)

To aZZ whom, t1-may concern:

Be it known that I, JAMES J. VOOD, a citizen of the United States, residing at Fort WVayne, in the county of Allen and State of Indiana, have invented certain new and useful Improvements in Electric-Arc Lamps, of which the following is a specification.

This invention introduces certain improvements in electric-arc lamps.

These improvements are in part applicable to lamps designed to beV fed byalternatingvv They are in part applicable to currents. lamps of the class known as carbon-feed lamps wherein the upper carbon is engaged directly with the feeding device, and they are in part applicable to inclosed-arc lamps.

One feature of lny invention which is especially applicable to alternating-current lamps is designed to effect a proper and gradual drawing of the arc without the objectionable dancing of the movable carbon that is liable to occur with lamps of this class. To this end I connect the armature or movable member of the electromagnet with the separating device for drawing the arc through the medium of a yielding member, as a spring, which is adapted to yield duringV the arc-drawing movement, and thereby permit the armature to be attracted suddenly Without imparting such sudden movement to the separating device, the latter being restrained in its action by the usual retarder or dash-pot, the said yielding member reacting against a relativelyunyielding member, which also forms part of the connection between said armature and separating device, so that said unyielding member limits the movement communicated through said yielding member or spring and upon the retraction of the armature transmits a movement in the contrary direction.

In the preferred and most simple form of lamp embodying my invention wherein a single magnet is employed to control both the separating and feeding movements, the separating device becomes a feeding device, and the relatively-unyield-ing member serves to transmit the feeding movements from the armature to said feeding device. The relatively-unyielding member constitutes a lostmotion device or movable stop' acting in opposit-ion to the yielding member or spring, so as to receive the reaction thereof and to provide a means by which the yielding member may be given an initial stress, so that upon the attraction of the armature the stress which is transmitted to the separating device is in excess of such initial stress. vention enables the pressure by which the separating movement is effected against the retardation of the dash-pot to be augmented so as to attain an initial pressure adequate Afor insuring a firm and progressive movement and to avoid the objectionable dancing effect heretofore experienced.

My invention also provides a convenient means for adjusting the lamp for greater or less current by varying the leverage with which the spring or yielding member acts to transmit its stress to the feeding device, and this without altering the initial stress of such spring. This I accomplish by causing the spring to act against one arm of a lever, which arm is made extensible by means of a nut or sleeve against which the spring acts and which screws upon the threaded portion on the lever so as to move toward or from the fulcrum of the lever the point of application of the stress of the spring.

-Those improvements which relate to the carbon-feed lamp involve means for making electrical connection between the trolley and its tube without danger of pitting the tube and provide an improved clutch by which the trolley grasps the carbon, means for properly centering the trolley when introducing the carbon, and an improved clutch for engaging and feeding the carbon.

Those improvements which are applicable to an inclosed-arc lamp include an improved globe-holder for the arc-inclosing globe and an improved construction of gas-cap for closing the top of said globe.

The several improvements provided by my present invention are especially designed for conjoint use in an inclosed-arc carbon-feed lamp to be employed withalternating currents. The preferred construction of such lamp is shown in the accompanying drawings, wherein-A y Figure l is a vertical mid-section of the entire lamp. Fig. 2 is a fragmentary vertical mid-section on a larger scale than Fig. 1, and in a plane at right angles to that of Fig. l, the planes of Figs. 1 and 2 being denoted, rc-

Thus my inspectively, by the line 1 l and the line 2 2 in Fig. 3. Fig. 3 is a transverse section on the line 3 3 in Fig. 2. Fig. 4t is atransverse section of the gas-cap, taken on the same plane as Fig. l. and showingits parts slightly separated. Fig. 5 is a plan, and Fig. 6 a transverse section, of the feeding-clutch. Fig. 7 is a plan of the globe-holder, of which Fig. 8 is a side elevation and Fig. 9 a fragmentary vertical section, the latter being an enlarged fragment of Fig. 2.' Fig. 10 is an elevation of one of the springs shown in Figs. 7, 8, and 9. Fig. 1l is a vertical mid-section of the trolley-tube, trolley, and upper carbon. Fig. 12 is an elevation of the trolley removed, of which Fig. 13 is a vertical mid-section. Fig. 14 is a cross-section on the line 14 14 in Fig. 12, and Fig. 15 is a plan or end View of the trolley. Fig. 16 is a fragmentary view of the intermediate or dash-pot lever of the feed mechanism, showing the adjustable spring connection. Fig. 17 includes a side and edge View of the link which constitutes the unyielding member of the connection between the armature and lfeeding' device.

In some respects the construction of lamp shown in the drawings resembles that set forth in my Patent No. 638,789, dated December 12, 1899.

Referring to the drawings, let A designate the mechanism-case; B, the frame supporting the mechanism; C, the usual main or outer globe; E E, the usual side rods, which, as shown, extend down within the globe and carry the lower-carbon holder, and M a regulating or control magnet or solenoid, the movable member or armature fm 0f which is connected to an armature-lever F, which is pivoted at a. The armature is shown as a U-shaped laminated solenoid-core and is connected to the arniatnre-lever F by springs s s, Fig. 8, in the manner fully set forth in my Patent No. 635,789.

Il is the clutch or clutch-lever, which in a lamp having a feed-rod would engage such rod, but in the particular construction of lamp shown engages the upper carbon I. The lower carbon J is shown as held in the lower-carbon holder-K, which may be of any suitable construction, the particular construction here shown being that which is set forth and claimed in my Patent No. 662,048, of November 20, 1900. The upper carbon I is held atiis upper end in a spring-holder L, formed at the lower end of a so-calledy trolley N, Figs. 11 to 15, which slides freely -in a trolley-tube D, which is fixed in place in the lamp, as shown in Figs. 1 and 2.

l will now describe the means for operating the clutch Il from the armature m of the control-magnet. In the construction shown the armature-lever F communicates the movements of the armature to an intermediate lever P, which is conveniently placed above it and which in turn connects through a link Q with one arm of the clutch-lever II, the 0pposite arm thereof being shown as forked and 'ing or arc-drawing movement thereof.

evaso? engaging an adjustable stop-screw b. A retarder R, of which a dash-pot is the best example, is connected in any suitable manner to the clutch H, so as to retard the separati convenient way of making this connection is by jointing the dash-pot directly to an arm, forming a prolongation of the lever P, as shown. The dash-pot has a check-valve c, which opens outwardly, so that it closes during 'the arc-drawing movement, and thereby acts to retard this movement, while during the feeding movement it opens, and consequently effects no retardation of the feed, this being a known expedient in lamps of this type. The lever P is fulcrumed at (Z to any suitable part, a pendent or bracket d being shown for this purpose projecting down from the top plate e of the mechanism-frame I3. The relatively yielding and unyielding members heretofore referred to are preferably interposed between the levers F and P and are shown as being respectively a spring S and link T. The spring S is shown as connected with the levers to the left of the fulcrums a and d in Fig. 2, while the link T is shown as connected to the right of these fulcrums, so that these two members act in opposition to each other. The link T is shown as pivotally connected at its lower end to the lever F by engaging a hole j' therein, while at its upper end it has a lost-motion connection with the leverP, formed as a slot p in this lever, in which the upper end of the link engages. The link is preferably formed as a bent wire, as shown in Fig. 17, its lower part t engaging the hole in the lever F and its upper part t engaging the slot in the lever I. Normally the tension of the spring S pulls down the short arm of the lever P and keeps its long arm pulled up, so that the link T is kept seated at the bottom of the notch p, so that the lost motion is kept taken up, and the abutting surfaces of the link are slit, constituting spaces forlimiting the contraction of the spring. Thus the spring may be stretched to any initial stress desired, the relativelyunyielding member T serving to receive the normal or initial reaction of the spring.

Upon turning on the current the magnet M is instantly energized and attracts its armature m with great force, thereby drawing it up4 and tilting the lever F to the position shown in dotted lines in Fig. 2. This communicates an upward movement through the link T, which slides its upper end t upwardly through the slot t to approximately the position shown in Fig. 1G. The same movement pulls down the lower end of the spring S, thereby increasing the tension or stress upon this spring. The lever P is now exposed to the unbalanced stress of the spring S, tonding to throw it up to the position indicated in dotted lines in Fig. 2; but this tendency is resisted by the retarder lt, so that the movement of the lever P occurs very slowly in response to the sudden movement of the lever IOO IIO

F. As the lever P slowly moves up under the moderating influence of the retarder or dash-pot it pulls up through the link Q upon the clutch H, causing the latter to engage the upper carbon I and lifting the tail of the clutch free from the stop-screw b until it is elevated approximately to the position indicated in dotted lines, its movement being arrested by the bottom of the notchp encountering the upper bend t of the link T, whereby the leverP is stopped in the position shown in dotted lines in Fig. 2. It will be perceived that this portion t of the link T constitutes, in effect, a movable stop, deriving its movements from the armature and acting in one direction as a more or less positive limit to th-e movement induced under the stress of the yielding member or spring S. In the upward movement of the clutch H it carries the carbon I with it,and thereby draws the arc. In this operation the clutch II constitutes a carbon-separating or arc-drawing device. Subsequently as the carbon consumes and the arc burns long the magnet M becomes weakened, relaxing its attraction for its armature, which accordingly descends, and in this movement the lever F pulls downwardly through the link T upon the lever P, so that the long arm of the latter is moved downward, thereby through the link Q lowering the clutch H and the carbon I to shorten the arc. This movement is not retarded by the dash-pot vR by reason of the opening ofthe valve c, so that the feed occurs promptly. IVhen this feeding movement has continued far enough to disengage the clutch so that the carbon I feeds down through it, the consequent shortening of the arc renergizes the magnet M, which reattracts its armature, thereby again communicating an upward movement through the link T, which again slides up in the slot p, thereby again throwing the unbalanced stress of the spring S upon the lever P to impart to the clutch an upward or separating movement. An important feature of this mechanism is that by reason of the relatively unyielding member T constituting a movable stop the spring S is enabled to be put under a considerable initial tension against this stop, so that when the armature movement occurs, by which the stop is displaced, the full tension of the spring is at once exerted to strongly and firmly press in the direction to draw the arc. This results in a uniform arc drawing or separating movement free from any iiuctuation or dancing, and consequently without flickering or flashing of the light.

It is practically advantageous to introduce a yielding member between the lever P and clutch H, which is conveniently done by interposing a spring Q' as a part of the link Q.

It is preferable to provide a cushion g, Fig. 2, to receive the impact of the armature when it falls. This cushion is shown-as placed in a recess in the bottom plate e of the mechanism-frame B. It is also preferable to provide a buffer of felt or other material to receive the upward impact or shock of the armature when attracted.

In a lamp of the type shown an important desideratum is to make the entire lamp as short vertically as possible. My invention provides an improved arrangement of the regulating mechanism which contributes greatly to this end. By placing the intermediate lever P above the armature-leverF the armature when retracted may be brought directly down upon the bottom plate without shortening the spring S and without exposing the spring Q beneath the mechanism-case.

An important feature of my invention relates to the means for adjusting the lamp for greater or less current. This I accomplish without affecting the initial stress of the spring S by varying the leverage or mechan.- ical advantage with which it acts upon the clutch and reacts upon the armature. To this end, since the spring is connected in tension between the short arm of the lever F and' the short arm of the lever P, I provide means for varying its leverage by varying the distance from the pivot or fulcrum at which it engages one or other of these levers. I prefer to provide the adjustment at its engagement with the lever P, as shown. As a convenient means for effecting this variation of leverage without requiring the dismounting of the spring, I have designed a screw adjustment by which the point of connection of the spring with the lever is readily moved toward or from the fulcrum-axis. vide a part movable along the short arm of the lever, which part is engaged by the spring, and I provide a screw adjustment for displacing this part toward or from the fulcrum-axis. In its most convenient and compact form this feature of my invention is constructed in the lnanner best shown in Fig. 16, where the 11pper end of the spring is looped around a nut h, so as to engage a circumferential groove therein, this nut screwing upon a screwthreaded pin or arm fi., projecting from the lever and forming part of the short arm thereof. By turning the nut so as to screw it toward the lever-fulcrum the point of application of the spring is displaced toward such fulcrum, as shown in dotted lines in Fig. 16. To adjust the lamp for a greater current, the nut is screwed toward the right to shorten the effective length of the short arm of the lever. For a less current it is screwed outwardly to increase the effective length of the short arm of the lever. Of course if this adjustment were applied instead to the lever F vthe adjustments would be made in the contrary directions. This mode of adjustment accomplishes its result by merely changing the leverage at which the spring acts and Without altering the length of the spring or affecting its initial stress.

In so-called carbon-feed lamps, wherein vertical compactness is attained by shortening the ordinary feed-rod into a mere plun- IOO Accordingly I pro- IIO ger, called the trolley, sliding` within a fixed tube, called the trolley-tube, and causing the feed-clutch to engage directly with the upper carbon, which slides up within the trolley-tube, difficulty is commonly experienced in conducting the current between the trolley-tube and trolley, since the slightest imperfection of contact is liable to result in the formation of small arcs which burn the conducting springs or brushes and pit the inner face of the tube. Only avery light rubbing contact can be made between the trolley springs or brushes and the tube, as otherwise such friction would be generated as would impair the free feeding dewn of the carbon. To overcome the disadvantages heretofore experienced, I provide a construction of trolley-brushes whereby these brushes or springs make edge contact with the tubular guide, the edges of the springs being` pre-41V sented against the inner face of the tube at so many points as to insure the making of a conductive connection such as shall avoid arcing or pitting. The trolley N is shown within the tube in Fig. ll and separately in Figs. 12 and 13. It is formed of a cylindrical plunger of suitable weight, having a suitable number of longitudinal grooves, in which are placed the contact springs or brushes jj, which at one end are fastened to the trolley by screws or otherwise, and at their other'or free ends press outwardly against the inner' wall of the tube. The free ends of these springs are bent so as to present their edges outwardly to bear against the tube. Preferably they are bent into U shape, as shown in Fig. 15, so that cach spring presents both edges of said U-shapcd portion to make edge contact with the inner surface of the tube. I prefer to use three springs, so that six edges are presented in contact with the tube. Thus very light springs may be employed, pressing outwardly with very gentle pressure, and yet by reason of the numerous points of contact with the tube they adapt themselves to all inequalities of surface and maintain ample conductive contact, thereby effectively preventing any arcing or burning, or the pitting or other injury of the tube. On the bottom of the trolley is formed the carbonholder L, consisting of a spring-clamp forming a yielding socket for receiving the upper end of the upper carbon I. The socket is preferably made integrally with the trolley, as shown, the thin metal tube forming the socket being elastic and being cut or slitted by two or more longitudinal cuts fr., which at their upper ends are carried around or continued by horizontal cuts Z. This forms each leaf of the socket of substantially L shape, so that it may yield either by expanding or contracting to fit slight variations in the diameter of the carbon, or may be distorted to adapt itself to a slightlycrooked carbon. The upper end of the trolley and the upper end of the tube D are provided with reciprocal means whereby to center the trolley as it is pressed up. These means consist of' a projection on one part and a socket in the other, one or preferably bot-h being conical. I prefer to form a cone n, Fig. 11, upon a plug o, which closes the upper end of the tube D, and to form a socket it' in the upper end of the trolley. In trimming the lamp it is only necessary after removing the consumed carbon to push the new carbon up into the tube D, thereby sliding up thev trolley until the latter strikes the stop-plug o and centers thereupon, and by the same movement seating the upper end ofthe carbon in the spring clamp or holder L. The trolley is formed with a slight flange q, making an easy fit with the tube, and the tube has screwed on its lower end a collar q', Fig. 11, the internal fiange of which projects sufficiently far to arrest the flange q and prevent the trolley dropping out of the tube when removing the consumed carbon. The clutch H being arranged beneath the mechanism-case and engaging the carbon where it is liable to be considerably heated is subject to injury through wear and heating of its surfaces engaging the carbon. To prolong the life of the clutch, I construct it with a lining ring or bushing II', (shown best in Figs. 5 and 6,) which is held in place by a small set-screw r, the end of which enters a circumferential groove in the bushing. Vhen a bushing wears, it can, by loosening the screw, be turned around circumfereutially to present new engaging surfaces or by partly withdrawing the screw it can be slipped out and inverted, thereby at least doubling the life of the clutch.

The lamp shown is a long-burning or inclosed arc-lamp, the inner or smaller globe U of which is held ina globe-holder V of improved construction. I'Ieretofore much trouble has been experienced in providing a suitable construction of holder for this inner globe, many complicated devices having been provided for this purpose. It is desirable that the base of the globe be held elastically, as any rigid holding means is liable to break it. It should also be constructed so as to be quickly and easily operated and should be as simple and cheap as possible and not liable to get out of order. My improved construction aims to fulfil these conditions. I preferably construct the globe-holder integrally with the fixed part of the lowercarbon holder K; but this is not essential. It is sufficient to provide any suitable globe seat, base, or socket u, Figs. 8"and 9, fastened in any suitable way to the bottom portion of the pendent frame-aa for example, in the manner shown in Fig. 1, where it is fastened by screws to the yoke E', uniting the lower ends of the rodsE E. The globe seat or base u preferably has a flange for supporting the foot of the globe, a packing u' being arranged to cushion the globe, as shown, though this is not essential. It is also desirable but not esssential that a flange u2 should be provided to inclose the foot of the globe, forming a sort IOO IIO

of cup; but this is also unessential. That which is essential is that the foot or neck of the globe shall be engaged at'substantially equidistant points by three (more or less) studs, pins, or clamps o c, mounted on springs, so that they shall be pressed yieldingly toward the globe, so as to hold it elastically at preferably three points. I prefer to provide leaf-springs w w, one of which is shown separately in Fig. 10, which are extended peripherally around the globe-seat, being fixed at one end to thebase u and carrying at their other ends the studs or clamps o. It is also desirable to provide a :means for adjusting the tension of these springs, and this I preferably attain by constructing the studs or clamps fu as screws, the threads of which en` gage threaded holes in the free ends of the springs. Other means `of adjustment may, however, be provided. The screw studs or clamps are screwed outwardly to admit of placing the foot of the globe in the holder, whereupon they are screwed up to embrace the neck of the globe between them with a suitable pressure. They cannot be made to press tighter against the glass than the tension of the springs, and hence the breakage of the globe by screwing up the screws too tightly is'avoided, the springs being made of proper stiffness to this end. The ends of the screw-studs are slightly upset, so that they cannot be lost out. The upper end of the globe U is closed, as usual, 4by a gas-cap W, which to allow for the expansion and contraction of the gases in the globe is provided with a circuitons gas-passage y, as usual, one end of which, y', Fig. 4t, opens within the globe, while the other end y2, Fig. 2, opens externally. This passage y is formed, as heretofore, by means of a groove in the upperside of the plate W, which groove is closed by fastening a flat plate W on the ytop'of the cast plate vW. This top plate has heretofore been fastened down by screws; but this is objectionable, since these screws interfere with the circuitous passage and occupy room otherwise needed therefor. My invention improves upon this construction by forming the plate W with asocket a; in its upper side, as shown in Fig. 4, of a diameter exactly equal tov or, in fact, very slightly less than that of the plate W'in forcing this plate down into the socket under heavy pressure. This makes a permanent union between the top plate and the casting and avoids the disadvantage of fasteningscrews.

In Fig. l, X is the reactive coil employed in constant-potential alternating-current lamps.

I have shown in Figs. l and 2 an air-chamber Y beneath the mechanism-case in order to protect the mechanism-case and its contents from the heat of the arc, which in lamps of this class is apt to be a serious consideration, whereby because of the compactness of the arrangement the arc is brought close beneath the mechanism-case. The outer case surrounding this chamber Y is perforated and communicates with an open hood, so that air can freely circulate on either side through the chamber Y to keep the parts cool.

My invention is by no means limited to the details of construction which I have hereinbefore set forth, but may be modified in many structural `respects without departing from its essential features. These features I have endeavored to set forth in the claims forming part of this specification. The unyielding member, of which the link T is an example, need not be absolutely unyielding, but should be substantially unyielding relatively to the yielding member or spring S.

I claim as my invention the following-defined novel features, substantially as hereinbefore specified, namely:

1. The combination of a magnet, its armature or movable member, a separating device for drawing the arc, a retarder for restraining the separating action thereof, and means for connecting said armature and separating device, comprising a yielding member and a relatively unyielding member, the former' adapted upon the attraction of said armature to transmit a stress to said device tending to move it in the separating direction, and the latter adapted upon the retraction of said armature to transmit a movement to said device in the contrary direction.

2. The combination of a control-magnet, its armature or movable member, a feeding device forseparating and feeding the carbons, a retarder for restraining the separating action of said feeding device, and means for connecting said armature and feeding device comprising a yielding member and a relatively unyielding member, the former adapted upon the attraction of said armature to transmit a separating stress to said feeding device, and the latter adapted upon the retractionof said armature to transmit a feeding movement to said feeding device.

3. The combination of a magnet, its armature or movable member, a separating device for drawing the arc, a retard er for restraining the separating action thereof, and means for connecting said armature and separating device, comprising a yielding member and a movable stop, the former under an initial stress, and the latter arranged to receive the reaction of said stress, the former adapted to transmit a stress upon the attraction of the armature, and the latter to transmit a movement in the opposite direction upon the :retraction of the armature.

4E. The combination of a control-magnet, its armature or movable member, a feeding device for separating and feeding the carbons, a retarder for restraining the separating action of said feeding device, and means for connecting said armature and feeding device comprising a yielding member and a movable stop, the former under an initial stress, and the latter arranged to receive the reaction of said stress, the former adapted upon the attraction of said armature to trans- IOO IIO

mit to said feeding device a separating stress in excess of its initial stress, and the latter adapted upon the retraction of said armature to transmit a feeding movement to said feeding device.

5. The combination of a control-magnet, its armature, an armature-lever, a feeding device for the carbon, a retarder for restraining the separating action thereof, a lever intermediate of said armature-lever and feeding device, and means for connectingr said levers comprising a spring and a movable stop, the latterscrving to resist the stress of the spring, whereby the spring may be put under an initial tension, the spring arranged upon the attraction ot' the armature to transmit its stress to said intermediate lever to impart a separating movement, and the movable stop adapted upon the retraction of the armature to impart a feeding movement.

G. The combination of a magnet, an arma ture-lever, a feeding device, an intermediate lever connected to said feeding device, and

lmeans for connecting said armature-lever and intermediate lever comprising a spring connecting said levers on one side of their fulcrums, and a relatively unyielding member connecting them on the opposite side of their fulcrums, said latter member having an engagement in one direction only so as to constitute a movable stop acting in opposition to vsaid spring.

7. The combination of a magnet, its armature, an armature-lever F, a lever P, a link T pivoted to one of said levers and engaging a slot in the other, a spring S connecting said levers in opposite position to said link, and a feeding device connected to said lever P.

S. The combination of a magnet, an armatu re-lever engaging the armature thereof beneath said magnet, a feeding device beneath vsaid armature-lever, an intermediate lever above said armature-lever connected to said feeding device on the one hand and to said armature-lever on the other, the latter connection comprising a spring and a movable stop, the latter serving to resist the stress of the spring, whereby the spring may be put under an initial tension, and a dash-pot connected to said feeding device.

9. The combination of a magnet, its armature-lever, a feeding device, an intermediate lever connected to said feeding device, a connection between said intermediate lever and armature-lever, and means for adjusting the point of-attachment of said connection to one of said levers so as to vary the leverage.

10. The combination of a magnet, its armature-lever, a feeding device, an intermediate lever connected to said feeding device, and a connection between said intermediate lever and armature-lever comprising a spring, and means for adjusting the leverage of said spring by displacing its point of connection with one of said levers toward or from the fulcrnm of such lever.

11. In an arc-lamp, the combination 0f a magnet, its armature-lever, a feeding device, an intermediate level', and a connection between said levers comprising a spring, and means for varying the leverage at which said spring acts consisting of an adjusting device for moving the point of attachment of said spring with the lever toward or from the ful crum ofthe lever.

12. In an arc-lamp, the combination of a magnet, its armature-lever, a feeding device, an intermediate lever, and a connection between said levers comprising a spring, and means for varying the leverage at which said spring acts by varying its point of connection to the lever in direction toward or from the fulcrnm thereof, and substantially perpendicular to the direction of stress of the spring, whereby the initial stress of the spring is not varied by such adjustment.

13. In an arc-lamp, the combination with a lever P having a screw-threaded arm fi, of an adjusting-nut 7?. screwing on said arm, and a spring S engaging said nut.

1st. In an arc-lamp, the combination with a lever P and a spring S acting against said lcver, of means for varying the leverage at which said spring acts, consisting of an adjusting-screw engaging said leverand adjustable thereon in direction toward or from its fulcrum, said screw having a circumferential groove, and said spring having a loop entering said groove.

15. The combination of a feeding-clutch and a removable bushing attached thereto having an inner gripping edge for engaging the movable electrode, and form ed externally with a .flange of greater width seated in the clutch.

16. The combination of a feedingclutch having a' circular recess, and an adjustable annular gripping edge seated therein for engagement with the movable electrode.

17. The combination of a feeding-clutch and a bushing therefor movable wit-hin said clutch to different positions.

18. The combination of a feeding-clutch having a set-screw o', with a removable bushing H having a circumferential groove adapted to be engaged by said screw.

19. In an arc-lamp, the combination with a trolley for engaging the carbon and its guiding-tube, of brushes for conducting the current between said trolley and tube attached to one part and arranged to press edgewise and to slide frictionally against the other.

20. In an arc-lamp, the combination with a trolley for engaging the carbon and its guiding-tube, of brushes for conducting the cnr rent between said trolley and tnbe consisting of metal springs attached to said trolley and bearing at their free ends against said tube, and bent to present at their free ends an edge contact with said tube.

21. In an arc-lamp, the combination with a trolley for engaging the carbon and its guidingtube, of brushes for conducting the current between said trolley and tube consisting IOO IIO.

IIS

of metal springs attached to said trolley and bearing at their free ends against said tube, their free ends being bent into channel form to present both edges thereof in contact with said tube.

22. In an arc-lamp, the combination with a trolley for engaging the carbon and its guidand conducting-brushes in said grooves con.

sisting of springs fastened at one end and pressing outwardly at their opposite or free ends, and bent at said free ends to present edge contact with the guiding-tube in Which said trolley moves.

24E. In an arc-lamp, the combination with a trolley for engaging the carbon and the guiding-tube of said trolley, the upper end of said tube and the upper end of said trolley being provided reciprocally with centering means adapted to center said trolley when pressed up Within said tube.

25. In an arc-lamp, the combination with a trolley for engaging'the carbon and the guiding-tube of said trolley, the upper end of said trolley being provided with a conical recess,

and the upper end of said tube being closed by a plug having a conical projection for engaging said recess and centering the trolley.

26. In an arc-lamp, a trolley for engaging the carbon having a carbon-holder consisting of a socket divided into segments by longitudinal and transverse slits, whereby said segments are adapted to yield in either direction.

27. In an arc-lamp, a trolley for engaging the carbon,the carbon-holder L consisting of a socket divided into segments by vertical slits 7c and horizontal slits Z, to the effect set forth.

2S. In an arc-lamp, a globe-holder consisting of a plurality of studs adapted to engage the neck of the globe, and springs engaging said studs and arranged to press them inwardly.

29. In an arc-lamp, a globe-holder consisting of a plurality of studs adapted to engage the neck of the globe, springs arranged to press them inwardly, and means for adjusting the tension of said springs.

'30. In an arc-lamp, va globe-holder consisting of a plurality of studs adapted to engage the neck of the globe, each stud movable independently of the others, and springs engaging the respective studs pressing them independently toward the center.

3l. In an arc-lamp, a globe-holder consisting of a plurality of screw-threaded studs adapted to engage the neck of the globe, and leaf-springs for pressing said studs inwardly each spring fixed at one end and having at its other a screw-threaded engagement with its stud, whereby the studs may be independently adjusted in their respective springs to vary their tension.

32. In an arc-lamp, a globe-holder comprising a flanged base u, leaf-springs w w each xed at one end to said base, and studs fu QJ carried on the free ends of said springs, pressed inwardly thereby proj ectinginwardly through the flange of said base, and adapted to engage the neck of the globe.

33. A globe-holder for an arc-lamp, coniprising a globe-seat, a spring extending peripherally With relation thereto, and an adj ustable clamp on the free end of the spring.

34. A globe-holder for an arc-lamp, comprising a globe-seat, a plurality of peripherally-extendin g springs mounted thereon,fiXed at one end, and having adjustable clamps on their free ends.

35. In an inclosed-arc lamp, a gas-cap consisting of a plate W grooved on its upper side to form a circuitous vent-passage, combined with a top plate W for closing said passage, the one plate being formed with a flange and the other fitting tightly within said flange and united thereto by being forced thereinto.

In witness whereof I have hereunto signed my name in the presence of two subscribing Witnesses.

JAMES J. VOOD.

Witnesses:

EDWARD A. BARNES, FRED S. HUNTING.

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