Ansonia Brass Copper Company v. Electrical Supply Company

by Henry Billings Brown

United States Supreme Court

144 U.S. 11

Ansonia Brass Copper Company  v.  Electrical Supply Company

STATEMENT BY MR. JUSTICE BROWN.

This was a bill in equity for the infringement of letters 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 water-proof and furnishing a proper insulation. With conductors of this character several accidents occurred in consequence of the conductor 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 through out 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.

'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 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 non-combustible, and it prevents the covering being ignited by the wire 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 non-combustible, 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 non-combustible 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 Fed. Rep. 81, and 35 Fed. Rep. 68,) and an appeal taken to this court.

Mr. Justice FIELD, dissenting. 35 Fed. Rep. 68, and 32 Fed. Rep. 81, affirmed.

Joshua Pusey and Chas. E. Mitchell, for appellant.

C. R. Ingersoll and M. W. Seymour, for appellee.

Mr. Justice BROWN, after stating the facts in the foregoing language, delivered the opinion of the court.

Notes