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U.S. Supreme Court

The Incandescent Lamp Patent, 159 U.S. 465 (1895)

The Incandescent Lamp Patent

No. 10

Argued October 29-30, 1894

Decided November 11, 1895

159 U.S. 465


With the exception of the third claim, viz., for "the incandescing conductor for an electric lamp, formed of carbonized paper, substantially as described," the claims in the letters patent No. 317,076, issued May 12, 1880, to the Electro-Dynamic Light Company, assignee of Sawyer and Man, for an electric light, are too indefinite to be the subject of a valid monopoly.

This was a bill in equity, filed by the Consolidated Electric Light Company against the McKeesport Light Company, to recover damages for the infringement of letters patent No. 317,076, issued May 12, 1885, to the Electro-Dynamic Light Company, assignee of Sawyer and Man, for an electric light. The defendants justified under certain patents to Thomas A. Edison, particularly No. 223,898, issued January 27, 1880; denied the novelty and utility of the complainant's patent, and averred that the same had been fraudulently and illegally procured. The real defendant was the Edison Electric Light Company, and the case involved a contest between what are known as the Sawyer and Man and the Edison systems of electric lighting.

Page 159 U. S. 466

In their application, Sawyer and Man stated that their invention related to

"that class of electric lamps employing an incandescent conductor enclosed in a transparent, hermetically sealed vessel or chamber from which oxygen is excluded, and . . . more especially to the incandescing conductor, its substance, its form, and its combination with the other elements composing the lamp. Its object is to secure a cheap and effective apparatus, and our improvement consists first, of the combination, in a lamp chamber composed wholly of glass, as described in patent No. 205, 144,"

upon which this patent was declared to be an improvement,

"of an incandescing conductor of carbon made from a vegetable fibrous material, in contradistinction to a similar conductor made from mineral or gas carbon, and also in the form of such conductor so made from such vegetable carbon, and combined in the lighting circuit with the exhausted chamber of the lamp."

The following drawings exhibit the substance of the invention:

Image a:

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The specification further stated that:

"In the practice of our invention, we have made use of carbonized paper, and also wood carbon. We have also used such conductors or burners of various shapes, such as pieces with their lower ends secured to their respective supports, and having their upper ends united so as to form an inverted V-shaped burner. We have also used conductors of varying contours -- that is, with rectangular bends instead of curvilinear ones; but we prefer the arch shape."

"No especial description of making the illuminating carbon conductors, described in this specification, and making the subject matter of this improvement, is thought necessary, as any of the ordinary methods of forming the material to be carbonized to the desired shape and size, and carbonizing it while confined in retorts in powdered carbon, substantially according to the methods in practice before the date of this improvement, may be adopted in the practice thereof by anyone skilled in the arts appertaining to the making of carbons for electric lighting or for other use in the arts."

"An important practical advantage which is secured by the arch form of incandescing carbon is that it permits the carbon to expand and contract under the varying temperatures to which it is subjected when the electric current is turned on or off without altering the position of its fixed terminals. Thus, the necessity for a special mechanical device to compensate for the expansion and contraction which has heretofore been necessary is entirely dispensed with, and thus the lamp is materially simplified in its construction. Another advantage of the arch form is that the shadow cast by such burners is less than that produced by other forms of burners when fitted with the necessary devices to support them."

"Another important advantage resulting from our construction of the lamp results from the fact that the wall forming the chamber of the lamp through which the electrodes pass to the interior of the lamp is made wholly of glass, by which all danger of oxidation, leakage, or short-circuiting is avoided."

"The advantages resulting from the manufacture of the carbon from vegetable fibrous or textile material instead of

Page 159 U. S. 468

mineral or gas carbon are many. Among them may be mentioned the convenience afforded for cutting and making the conductor in the desired form and size, the purity and equality of the carbon obtained, its susceptibility to tempering, both as to hardness and resistance, and its toughness and durability. We have used such burners in closed or hermetically sealed transparent chambers, in a vacuum, in nitrogen gas, and in hydrogen gas; but we have obtained the best results in a vacuum or an attenuated atmosphere of nitrogen gas, the great desideratum being to exclude oxygen or other gases capable of combining with carbon at high temperatures from the incandescing chamber, as is well understood."

The claims were as follows:

"1. An incandescing conductor for an electric lamp, of carbonized fibrous or textile material, and of an arch or horseshoe shape, substantially as hereinbefore set forth."

"2. The combination, substantially as hereinbefore set forth, of an electric circuit and an incandescing conductor of carbonized fibrous material, included in and forming part of said circuit, and a transparent, hermetically sealed chamber, in which the conductor is enclosed."

"3. The incandescing conductor for an electric lamp, formed of carbonized paper, substantially as described."

"4. An incandescing electric lamp consists of the following elements in combination: first, an illuminating chamber made wholly of glass hermetically sealed and out of which all carbon-consuming gas has been exhausted or driven; second, an electric circuit conductor passing through the glass wall of said chamber and hermetically sealed therein, as described; third, an illuminating conductor in said circuit and forming part thereof within said chamber, consisting of carbon made from a fibrous or textile material having the form of an arch or loop, substantially as described, for the purpose specified."

The commercial Edison lamp used by the appellee, and which is illustrated below, is composed of a burner, A, made of carbonized bamboo of a peculiar quality, discovered by Mr. Edison to be highly useful for the purpose, and having a length of about six inches, a diameter of about five one-thousandths

Page 159 U. S. 469

of an inch, and an electrical resistance of upward of 100 ohms. This filament of carbon is bent into the form of a loop, and its ends are secured by good electrical and mechanical connections to two fine platinum wires, B, B. These wires pass through a glass stem, C, the glass being melted and fused upon the platinum wires. A glass globe, D, is fused to the glass stem, C. This glass globe has originally attached to it at the point d a glass tube by means of which a connection is made with highly organized and refined exhausting apparatus, which produces in the globe a high vacuum, whereupon the glass tube is melted off by a flame, and the globe is closed by the fusion of the glass at the point d.

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Upon a hearing in the circuit court before Mr. Justice Bradley upon pleadings and proofs, the court held the patent to be invalid and dismissed the bill. 40 F. 21. Thereupon complainant appealed to this Court.

Page 159 U. S. 470

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