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UNITED STATES.V ¿PATENT CARL HEINRICH ELOEENZ MÜLLER, on HAMBURG, GERMANY.

INCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 317,171, dated May 5, 1885.

Application filed June 14, 1884. (Xo model.) ' Patented in England October 2, 1882, No. 4,676. -

To all whom it may concern. Be it known that I, CARL HEINEIcII FLO

RENZ MÜLLER, a subject of the Emperor of Germany, and a resident of Hamburg, in the German Empire, have invented certain new and useful Improvements in Incandescent Electric Lamps, of which the following is a speciñcation. ­ .

lVIy invention relates to improvements in electric lamps where the light is produced by the incandescence of a carbon filament in a Vacuum; and the `objects of my improve ments are, first, to shape the carbon filament in such a manner that around the axis of the lamp or bulb an equal lighting-surface will be visible; and, second, to facilitate the con nection of the carbon ñlament with the glass bulb. I attainthese objects by the device illustrated in the accompanying drawings, in which

Figures l and 2 are side elevations of my improved electric lamp from two different points of vieW,-situated at right angle to each other. Fig. 3 is a top view.

Similar letters refer to similar parts through out the several views. The carbonV ñlaments of incandescent lamps

as used up to this day allow only a single line or little-more to be visible when observed from certain points of View, as the ascending part of the bow obscures the descending one, and vice versa. The diffusion of the light at such points of view is proportionately smaller than at such point-s where the complete bow can be seen, as the quantity of the diffused light decreases with the decreasing lighting surface. -

It has been proposed to make the carbon filament inthe form of two spirals crossing each other, in order that the ñlament can eX pand and contract freely; but the spirals have been of a very compact form, consequently each spiral obstructs a considerable portion of the light emitted by the other. According to my invention the carbon fila

ment a is shaped in such a manner as to form two open cylindrical or conical spirals cross ing one another, which terminate in a bow, c', common to both, the diameter of said bow ' being the same or nearly the same as that of

the spirals. The two spirals and the termi nal bow are made of a single Iilament bent in the manner shown, or of two filaments united at one of their ends, and the free ends are connected to the platinum wires b in any convenient manner. 4The conducting-wires b are sealed into glass tubes c, which, at their upper extremities, are bent outward and pass . 4through the side walls of the small protuber ance c', formed 011 the bulb c at points dia metrically opposite to each other. The glass tubes c are connected together and braced by meansof the glass bars d. The bulb is sealed at the-point f on the summit of the bulb in the usual way after a sufficient vacuum has been produced within the bulb. This ar rangement of the point f causes the light of \ the lamps to be diüused more equally from the incandescent carbon, as no projection, 8vo., will interrupt the globe or otherwise shaped surface of the glass bulb. ~Having thus fully described my invention,

what I desire to claim, and secure by Letters Patent, is- p `

1. In an incandescent lamp, a carbon iila­` ment in the shape of an open double spiral, ` the windings of which extend ̀ in an inclined horizontal direction and cross each other, so that the ñlament presents an equal amount of lighting-surface‘on all sides, substantially as and for the purpose set forth.

2. In an incandescent electric lamp, a car bon ñlament, a, of the shape of an open double spiral, the windings of which extend in an inclined horizontal direction and cross each other, terminating in a bow, a', the filament 'thus formed presenting an ̀ equal amount of

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lighting-surface from all sides, substantially 4 as and for the purpose set forth. ,

3. The combination, in au incandescent electric lamp, of the bulb e, ‘having the pro tuberance e', with the connecting-wires b, .in cased in the glass tubes c, the outer ends of which pass through the walls ofthe bulb at Vpoints diametrically opposite to each other, together with the bars d and the carbon fila-` ment a, substantially as and ̀ for the purpose set forth. _ ` ` ` , "

4. The combination, in an incandescent electric lamp, of the bulb c, Vconnecting-wires .Iool

317,171

of of windings of which cross one another, termi- l 4’

1 i ,' ` hating in a bow, a', substantially as and for CARL HEIBRICH FLORE“ MULLER' 5 the purpose set forth. Witnesses:

In testimony that I claim the foregoing as ALEXANDER SPECHT, my invention I have signed my name, in pres` DIEDRIOH PETERSEN.