"In the accompanying illustration is shown a new design in the manufacture of incandescent electric lamps, the object of the inventor being to arrange the filament so as to produce a maximum and symmetrical distribution of light-rays, or, in other words, the same measurement of maximum candle-power at every point in the horizontal and vertical plane.

"Referring to the illustration an ordinary incandescent bulb is used and the pendent glass mount is sealed within the top, conducting wires being connected to the carbon filament in the usual manner. The filament, however, is wound spirally, there being three convolutions. These are in fact two spirals, which are alike in form and arrangement. Thus the lower bend of the double spiral merges into the two central convolutions, and these again merge into the upper convolutions, whose terminals connect with the wire conductors. The spirals are wound in opposite directions and the convolutions are symmetrically arranged one exactly opposite another horizontally. An important characteristic of this filament arrangement is that the relative diameters of the several convolutions differ so that when seen in an end view the convolutions appear in different horizontal planes. The upper convolutions are narrower than the lower ones. The central convolutions are wider than the latter, and hence each set of opposite convolutions is so placed that it is seen from below, and therefore throws light downward, independently of the other two. In this way a maximum aggregation of light can be obtained in a downward direction. The side or lateral distribution of light is also claimed to be uniform, thus perfectly symmetrical effect is obtained.

"To support and steady the filament a glass anchor is employed, which depends from the mount and is formed integrally therewith. This is provided with a wire extension which is rigidly attached to the centre of the lower bend or convolution of the filament. This anchor is also claimed to serve another important function, in that it draws to itself by static induction the carbon dust or fine particles of carbon which are given off from the filament as it grows old and which are ordinarily deposited on the bulb. This obviates the discoloring of the bulb under long-continued service.

"This lamp is the invention of Mr. Glenn C. Webster, of Warren, Ohio, and has been assigned to the Sterling Electrical Manufacturing Company, of Warren, Ohio."

References
1) "Symmetrical Distribution from Incandescent Filaments," American Electrician, Vol 13, Oct 1901, pg 513.
2) Glenn Cannon Webster, "Incandescent Electric Lamp," U. S. Patent No 708,432, Sep 2, 1902.
3) "New Ideas in Incandescent Electric Lamp Manufacture," Electrical Review, Vol 41, No 14, Oct 4, 1902, pp 451-452.