Edison Electric Light Co. v. United States Electric Lighting Co.

• Decision Date: 04 October 1892
• Citation: 52 F. 300
• Parties: EDISON ELECTRIC LIGHT CO. v. UNITED STATES ELECTRIC LIGHTING CO.
• Court: U.S. Court of Appeals — Second Circuit

52 F. 300

EDISON ELECTRIC LIGHT CO. v. UNITED STATES ELECTRIC LIGHTING CO.

United States Court of Appeals, Second Circuit.

October 4, 1892

Kerr &amp Curtis, Edward Wetmore, Samuel A. Duncan, and Frederic H Betts, for appellant.

Eaton &amp Lewis, C. A. Seward, Grosvenor P. Lowrey, S. B. Eaton, Albert H. Walker, and Richard N. Dyer, for respondent.

Before LACOMBE and SHIPMAN, Circuit Judges.

LACOMBE Circuit Judge.

On January 27, 1880, under an application filed November 4 1879, letters patent No. 223,898 were issued to Thomas A. Edison, and by subsequent assignments passed to the complainant. The four claims of the patent are as follows:

'(1) An electric lamp for giving light by incandescence, consisting of a filament of carbon of high resistance, made as described, and secured to metallic wires, as set forth. (2) The combination of carbon filaments with a receiver made entirely of glass, and conductors passing through the glass, and from which receiver the air is exhausted, for the purposes set forth. (3) A carbon filament or strip coiled and connected to electric conductors so that only a portion of the surface of such carbon conductors shall be exposed for radiating light, as set forth. (4) The method herein described of securing the platina contact wires to the carbon filament, and carbonizing of the whole in a closed chamber, substantially as set forth.'

In the lamp made by defendant the carbon conductor is not coiled as indicated in the third claim, nor is it secured as indicated in the fourth, nor does complainant contend that either of these claims is infringed. The circuit court held that the first claim was by its phraseology limited to lamps in which (among other things) the leading-in wires are 'secured to the filament according to the method of the patent, that is, by cement carbonized in situ,' and that as defendant uses clamps for this purpose it does not infringe. This construction of the first claim has been acquiesced in by the complainant, which has not appealed from the decision. There remains for consideration only the second claim.

The defendant's burner is of carbon, so small in cross section that, by the ordinary usage of common speech, it may be fairly called a 'filament.' The receiver, which contains the burner, is made entirely of glass. The conductors, which connect with the burner, pass through the glass, and from the receiver the air is exhausted. Defendant contends, however, that the specifications of the patent and the prior state of the art require that this second claim be so limited in construction that defendant's apparatus will not fall within its terms, and that, unless so limited, such claim is directly anticipated, or untenable as not involving patentable novelty.

Lamps devised to give light by means of the electric current are broadly divided into two groups, the arc and the incandescent. In the former two conductors or electrodes are so arranged that, when in operation, they are slightly separated, with their axes in the same vertical line. The current leaps across the intervening space, tearing off and partially vaporizing particles from the opposed ends of the electrodes, and developing heat and light in the ends of the electrodes and in the flying particles between them. In order to provide a current which shall be as effective as possible at the place where it develops light, not only the conductors, which bring it from the source of supply, but also the electrodes themselves, forming part of the conducting circuit, are devised to present but small resistance to the passage of the current. The effective resistance begins when the break in the circuit is reached. In an incandescent lamp there is no break in the circuit, but there is introduced into it a piece of poorly conducting material, which is so arranged that its resistance to the passage of the current will develop heat sufficient to bring it to a state of incandescence. The wires which conduct the current to the place where it is thus developed by resistance are so devised as to present but small resistance to its passage. The effective resistance begins where the piece of poorly conducting material (the burner or illuminant) is placed, and the lamp expires when the burner is consumed, breaks or wears away. The longer the life of the burner the longer the life of the lamp, and the more available it becomes for practical electric lighting. The selection of materials for the various parts of the circuit thus formed, their manipulation, arrangement, and operation, have for many years occupied the attention of experimenters, and the results of their labors, made public from time to time, constitute the state of the art of incandescent electric lighting.

The patent sets forth that 'the object of the invention is to produce electric lamps giving light by incandescence, which lamps shall have high resistance, so as to allow of the practical subdivision of the electric light. ' By the phrase 'subdivision of the electric light' is meant such a subdivision of the electric current that at several illuminating foci, supplied from the same source of electricity, there shall be developed lights of moderate intensity,--comparable to those given out by ordinary gas jets,-- and the problem to be solved required a system and apparatus which would admit of the development of these moderate lights in sufficient number, and at so low a cost, as to be commercially useful.

Prior to 1879 experimenters seemed to have reached the conclusion that success was to be attained, if at all, by modifications of the arc lamp, but up to that time no lamp, arc or incandescent, had been given to the public, which, with the means then existing for generating and distributing the electric current, accomplished this result. Since the date of the patent in suit electric lighting by lights of moderate intensity has become a commercial success. Subsequent improvements in the lamps and in other parts of the system have undoubtedly contributed materially to its development, but the record abundantly shows that with lamps such as the patent describes, constructed with the skill then known to the art, and operated under the conditions admitted by the generating and conducting apparatus then existing, it becomes practical for one generator to operate a considerable number of lamps, located at reasonable distances from it, and which at the same time were economical, durable, and cheap enough to be commercially useful, and so simple and reliable that they could be manipulated by the public. In view of the utter failure of the prior art to produce any such subdivision of the electric light, a lamp of this kind, which was capable of economical use in factories, large buildings, and in smaller buildings contiguous to each other,-- in other words, available for isolated lighting,-- should be considered commercially successful, though further development were needed to enable it to compete with gas for domestic lighting on even approximately equal terms. What, then, was the contribution to this solution of the problem which Edison gave to the world by the patent in suit?

Commercial and domestic exigencies required that the lamps should be so arranged that each derived its power independently from a common source, and not through another lamp, so that they could be individually lighted or extinguished at will, and the breaking down of a single lamp would not break the circuit. This is effected by what is called the 'multiple arc' arrangement, the wires leading to and from each light being so connected with the main conductors as to form a separate circuit for each light. In this arrangement no greater electromotive force is required for a large number of translating devices than for a single one, the current being graduated to the number employed. The lower the resistance of each illuminating conductor, the greater the current it requires, and as their number is increased, their individual resistances remaining constant, the size of the main conductors must be likewise increased, an increase which, in the prior art, soon involved such an expense for main conductors as to preclude commercial success. The amount of heat developed by the passage of an electric current is greater as the flow of the current is greater. It is also greater as the resistance of the conductor is greater, and all electric conductors vary in resistance directly as their lengths and inversely as their cross sections. Conductors of different materials have also different specific resistances. The quantity of heat developed in a translating device is independent of, but the degree of heat (i.e., the temperature) is dependent on, the extent of radiating surface. In the lamp shown in the patent these laws are availed of; the ratios of resistance of the burner to the resistance of the entire circuit and to its own radiating surface being so graduated that a light of the required intensity is produced by the expenditure of so small an amount of current at each illuminant focus as to admit of main conductors sufficiently small, and therefore sufficiently low priced, to warrant the introduction of the system into public use.

It is not necessary to enter into any elaborate discussion of the prior state of the art, so far as it bears upon the question of the patentable novelty of such embodiment of the principle of high resistance and small radiating surface. Irrespective of all patents or publications of others, the philosophy of that method of producing light is undoubtedly found stated clearly and sufficiently, and applied to the production of an incandescent platinum burner, in Edison's French patent, No. 130,910, taken out May 28, 1879. Whether, under section 4887 of the Revised Statutes, that...