Important Decision on Tesla Split-Phase Patents

Judge Archbold, in the United States Circuit Court, Eastern District of Pennsylvania, has just handed down a decision in the suit of the Westinghouse Electric and Manufacturing Company vs. H. C. Roberts and the Sangamo Electric Company, which has an important bearing on alternating-current meters and fan motors. The suit was under the so-called Tesla split-phase patents. The defendants' device against which suit was brought was the Sangamo electric meter. The Court, after a careful review of the testimony, decided that the complainant had proved satisfactorily that Tesla's date of invention preceded that of Ferraris's and others, and that the device in question was an infringement.

The importance of these patents is great, as some of the most successful alternating-current meters and motors of small size are tributary to them.

The following is an abstract of Judge Archbold's review of the testimony:

The patents in suit and those on which they are based, or which are kindred to them, have been so fully considered in previous cases which until recently have also been uniformly in their favor, that little is left to be brought forward with regard to them.

The derivative patents in suit, numbers 511,559 and 511,560, were first considered in the Dayton fan and motor case, 106 Fed. 724; affirmed in 118 Fed. 562, and a decision rendered in substantial accord with those which had preceded it. One defence there, as here attempted to be made, was that it involved no inventive skill when once the practicable use of alternating currents of different phase was established, to substitute the dephased split current which was a well recognized equivalent; but it was not so held, nor can it be here.

The patents in suit were also before Judge Lacombe in the Westinghouse Electric and Manufacturing Company vs. the Catskill Illuminating and Power Company, 110 Fed. 377. In addition to the attack made upon them in other cases, it was further urged that, in a paper read by Professor Ferraris before the Royal Academy of Sciences, of Turin, Italy, March 18, 1888, a portion of which was published on April 22 following, at Milan, in L'Elettricita, not only was there a full disclosure of the transmission of electric power by means of alternating currents of different phase, but also the use for the same purpose of a dephased split current derived from a single source, the same as in the patents in suit. Upon a due consideration of the opposing proofs the invention of Tesla was held to be carried back of this publication; but on appeal, the decision was reversed, the evidence brought forward by the complainants not being considered sufficient for that purpose; 121 Fed. 831; a conclusion which was followed by Judge Colt in a case by the same plaintiffs against the Stanley Instrument Company, in the first circuit, not yet in print. This, and the matter of infringement, are the overshadowing questions in the present case.

The Ferraris publication, as we have seen, was April 22, 1888, and the patents in suits were not applied for until December 8 following. To relieve from this apparent priority the invention has, therefore, to be carried back of the earlier date by competent and convincing evidence. That Tesla, early in May, 1888, had a complete grasp of the split-phase idea is established by his application of May 15 for patents, Nos. 511,915 and 555,190, which embody it, the same that were before Judge McPherson in the Scott & Janney case 97 Fed. 582, already alluded to. This is important evidence which can not be contradicted and I, therefore, start with it. Not only is the invention beyond question carried back by it to the date named, which is within twenty-three days of the Ferraris publication, but from the known order of events, a patent not being able to be worked out in a day, ground is thus persuasively laid for an earlier date if there is any fair evidence to warrant it. In the face of it, I hardly see how we can doubt the accuracy of Mr. Page's statement that Tesla disclosed to him the principles of the invention somewhere in the first part of April of that year. His testimony on this point is specific and convincing. In the fall of 1887 and spring of 1888, as he says, he was engaged in developing in the Patent Office a number of Tesla's inventions, and among them the poly-phase motors and transformers which were patented May 1, 1888. These were prosecuted to an allowance in the early part of April, the final fees, as shown by the books of the firm of which he was a member, having been forwarded to Washington on April 6. After having secured the allowance of this group and made arrangements for similar applications in a number of foreign countries for patent to issue simultaneously therewith, Tesla gave him the material for application one feature of which was the inducing of one current from another in the operation or construction of a motor, and in this connection disclosed to him his plan for operating his polyphase motors by means of a single split-phase circuit. Startled by this revelation and questioning whether the claims which he had drawn in the pending cases would protect this new improvement he had a long conference with Tesla, getting from him all that he could as to the different ways he proposed to operate this two-wire system. It seems to me convincingly established that prior to April 22 the date of the Ferraris publication, Tesla had disclosed to Mr. Page, his solicitor, the principle of his split-phase adaptation.

But the testimony of Mr. Page is by no means all there is upon this subject. Mr. A. S. Brown formerly connected with the Western Union Telegraph Company, became interested in the summer or fall of 1887 in bringing out the original Tesla motor; and he testifies that once when it was first brought to his notice it occurred to him as a great objection that it required two separate currents; not long after which Tesla showed him how it could be operated on a single main line from the generator. So far as I have considered only the proofs, about which no question can be raised, and basing my decision solely upon them, I am satisfied that the patents should be sustained.

The question of infringement still remains. At the time suit was brought, the defendant, Roberts, was engaged at Philadelphia in the sale of Gutmann recording wattmeters, as agent for the Sangamo Electric Company, of Springfield, Ill., by whom they were made.

It is contended that a meter is not a motor, and that on this ground of itself no infringement can be charged. No doubt the strict object of a meter of this class is to measure and record the element which passes through or actuates it, gas, water, the electric current, or whatever it may be; but where, as here, it is, in mechanical construction, nothing more than an adopted motor with meter attachments, it can not escape infringement on that plea.

The Tesla motor as an invention, was first in its own peculiar field, and is entitled in consequence to a liberal application of the doctrine of equivalents, and of the substantial equivalency of the defendants' device I am fully convinced. The significant thing in each is the conjoint or resultant action of the two opposite sets of poles, the magnetic influence, whether of attraction or repulsion, waxing and waning, and shifting progressively about the armature, of the existence of which there can be little doubt. It is persuasive of the equivalency of operation which is so contended for, although by no means conclusive of it, in a patent applied for by Tesla May 20, and granted December 3, 1889, this equivalency is assumed without explanation as being within the terms of the invention. Other confirmations of the equivalency of the two arrangements with that of a Tesla motor, as well as with each other, could be drawn from this record, but these must suffice. They establish to my satisfaction the general infringing character of the defendants' meter as is charged. Finding therefore that the patents in suit are valid and have been infringed, a decree is directed in favor of the complainants in the usual form, with costs.