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Ansonia Brass & Copper Co. v. Elec. Supply Co., 144 U.S. 11 (1892)

Ansonia Brass and Copper Company v. Electrical Supply Company

No. 165

Argued January 19, 1892

Decided March 14, 1892

144 U.S. 11


Letters patent No. 272,660, issued February 20, 1883, to Alfred A. Cowles for an "insulated electric conductor," are void for want of patentable novelty in the alleged invention covered by them.

The cases reviewed which establish (1) that the application of an old process or machine to a similar or analogous subject, with no change in the manner of application and no result substantially distinct in its nature, will not sustain a patent, even if the new form of result had not before been contemplated, and (2) that on the other hand, if an old device or process be put to a new use which is not analogous to the old one, and the adaptation of such process to the new use is of such a character as to require the exercise of inventive skill to produce it, such new use will not be denied the merit of patentability.

The Court stated the case as follows:

This was a bill in equity for the infringement of letters

Page 144 U. S. 12

patent No. 272,660, issued February 20, 1883, to Alfred A. Cowles, for an "insulated electric conductor."

In his specification, the patentee stated that

"Before my invention, copper wires had been covered with one or two braidings of cord, and paraffine, tar, asphalt, and various substances had been employed for rendering the covering waterproof and furnishing a proper insulation. With conductors of this character, several accidents occurred in consequence of the conductor's becoming heated and setting fire to the insulation. For this reason, objections were made to insuring buildings against loss by fire where electric lamp wires were introduced. To render the conductor fireproof without interfering with the insulation led me to invent and manufacture the insulated electric conductors to which the present invention relates, which conductors have gone extensively into use during about a year and a half before the date of this specification."

His method of preparing the wire was stated substantially as follows: the wire was first passed through a braiding machine, and a layer of cotton or other threads braided about it. The covered wire was then passed through a vessel containing paint, preferably white lead or white zinc ground in oil, and mixed with a suitable drier. A second braiding was then applied directly upon the fresh paint. The threads thus braided upon the paint force the paint into the first braided covering, and at the same time the paint oozes through between the threads. In this way, the paint was incorporated throughout the braided covering and filled up the pores, and the wire was thus perfectly insulated, and there was no possibility of inflaming the covering. "With intense heat, the threads may char, but they will not burn."

"If desired," said he,

"a coat of paint may be applied outside of the outer layer of fibrous material, and this may be colored, so as to be used in distinguishing the wires. It is always preferable to braid the second or subsequent coats upon the paint when fresh, but I do not limit myself in this particular, as the paint may be dried, or partially so, before the next layer of braiding is applied. Paint might be applied to the wire before the first braiding. "

Page 144 U. S. 13

"I am aware that wire has been covered with braided threads; also that India rubber, asphaltum, and similar materials have been applied upon the covering, either hot or cold; but one coating of such material was allowed to set or harden before the next layer of braided material was applied. Hence the asphaltum or similar material was not forced into the interstices, and besides this, all these substances ignite by the wire's becoming heated, or fire will follow along upon such covering."

"I have discovered that ordinary paint, composed of lead or zinc with linseed oil, is practically noncombustible, and it prevents the covering's being ignited by the wire's becoming hot if there is a resistance to the electric current. Besides this, fire will not burn along the conductor, as is the case where the fibrous covering is saturated with asphaltum, India rubber, or similar material."

"I claim as my invention:"

"1. The method herein specified of insulating electric conductors and rendering the coating substantially noncombustible, consisting in applying a layer of fibrous material, a layer of paint, and a second layer of fibrous material upon the paint before it dries or sets, substantially as set forth."

"2. An insulated and noncombustible covering for electric conductors, composed of two or more layers of cotton or similar threads, with paint that intervenes between the layers and fills the interstices of the covering, substantially as set forth."

Upon a hearing upon pleadings and proofs in the circuit court, plaintiff's bill was dismissed, 32 F. 81 and 35 F. 68, and an appeal taken to this Court.

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