(after stating the facts). Applications for the patents in suit were filed on December 8, 1888. Shallenberger on April 20, 1888, and Eerarris 'on April 22, 1888, made disclosures that void these patents unless the fact be that Tesla made the improvements in.question at an earlier date. May 15, 1888, Tesla applied for patents, *711which were granted as Nos. 555,190 and 511,915, on the inductive split-phase motor. This form was then regarded by Tesla and his attorney as more important than the derivative split-phase motor. Shortly after-wards the Westinghouse Company began negotiations for the purchase of the Tesla motor inventions; arrangements were consummated in July; and Tesla thereupon went to Pittsburg to instruct the Westinghouse engineers. Delay from May to December is thus accounted for. Tesla has no pecuniary interest in this litigation. His testimony is positive that he operated the “Exhibit Motor” in all of the ways involved in these patents as early as September, 1887. The “Exhibit Motor,” as we understand it to have stood in September, was a rotating-field motor, the ends of whose windings were loose. These four wires could be coupled to the four wires of a two-phase alternating current generator, and the motor would then run in the manner described in the basic patents of May 1, 1888. These four wires could also carry, in turn, each of the phase-splitting means covered by the patents in suit, and when so equipped could be coupled to the two wires of a single-phase alternating current generator, and the motor would then run as an inductive or a derivative split-phase motor. So the exhibit is not re^ garded as proving anything beyond its capability of having built into it the phase-splitting devices. But the prolonged cross-examination, in our judgment, does not derogate in the least from the direct testimony that the exhibit was used as stated.
Brown, an electrical engineer, in 1887 and 1888 was financially concerned in the inventions that Tesla was then making. Pie has no interest in this litigation. When Tesla showed him the polyphase motor, designed to be coupled to the four wires of a two-phase generator, he raised the objection that it would not work in connection with the systems of single-phase generators and line-wires which were then in general use throughout the country. His testimony is positive that shortly afterwards, in the “summer” or “summer or fall” of 1887, Tesla fully disclosed the methods and means of the split-phase motor by the use of the “Exhibit Motor.” We are not impressed by the parallel columns of alleged discrepancies between his testimony and that of Tesla. Advocates’ argument is familiar that if witnesses agree in details their stories have been fixed up, and if they disagree in details neither is to be believed in respect to the vital matters about which they are in accord. So far as we can judge from the printed page, Brown was a reliable witness. It should not be doubted that he saw at some time what he says he saw. The Court of Appeals for the Second Circuit (121 Fed. 831, 58 C. C. A. 167), on a record less complete than that presented here, concluded that Brown was mistaken in the year; that he first saw the split-phase motor'in the “summer” or “summer or fall” of 1888. We find that Brown was not mistaken, for these reasons: He fixes the place at Tesla’s laboratory, 89 Diberty street, New York. Tesla gave up this laboratory and went to Pitts-burg in July, 1888, stayed a year, and when he returned to New York took quarters in a different street; and Brown relates the time to the early days of the polyphase invention. As Tesla began filing applications for split-phase improvements as early as May, 1888, for Brown to have seen for the first time the “Exhibit Motor” operated as a split-*712phase motor at the Liberty street laboratory in any summer or fall, the year 1887 must be accepted.
Nellis ran a stationary engine at 89 Liberty street. Tesla rented power from his employers. Nellis sometimes stayed at night to furnish power for Tesla and was admitted to the laboratory. His testimony appeals to us as that of an uneducated, entirely disinterested and honest witness. He says that he saw Tesla operate the “Exhibit ■Motor” with two wires, holding one in each hand and touching one and then the other to the motor, whereupon it would turn one way and then reverse. Of course the motor would not operate unless the circuit was closed; but neither Nellis’s failure to see accurately nor his mistakes in narrating what he saw should deprive his testimony of the effect that the exhibit was operated as a two^wire rotating-field motor. The time was in the fall or winter. The only fall or winter during which these things could have occurred at 89 Liberty street was that of 1887.
The absence of other physical exhibits is accounted for by a fire in Tesla’s laboratory. By mere chance the “Exhibit Motor” was not destroyed. It was at the Patent Office at the time, for use in the interference case between Eerarris and Tesla.
Page, attorney for Tesla in securing patents, is convincing in his testimony that Tesla fully disclosed the split-phase inventions, including those of .the patents in suit, in the early part of April, 1888. He fixes the time positively as being later than the 6th and earlier than the 18th of that month. A canceled check fixes April 6th as the day he paid the final fees on the basic patents which were issued on May 1st. He is sure that Tesla had not then informed him of the split-phase methods and means, because, when told, he was greatly perturbed over the question of having the basic patents withheld from issue on the date already fixed upon. After consulting with his then partners in New York, he finally went-to Washington to confer with an associate. This date is fixed by a hotel charge as being the 27th. He is positive that the disclosure was more than a -week earlier, because it was made in connection with Tesla’s discussion with him of an application for a patent on an alternating current regulator, issued October 9, 1888. This application was filed April 24, 1888. A bill for services and disbursements shows that the drawings were paid for on the 21st, and that the written part of the application was completed on the 18th.
This is not a case where witnesses, years afterwards, are brought in to antedate an alleged anticipation by the efforts of unaided memory. Certain time-marks are indisputably fixed. The only escape would be to discredit the accounts of the occurrences themselves. Furthermore, it is not as if the witnesses were now called for the first time. Tesla and Page particularly have had this question brought to their attention repeatedly, beginning with the Eerarris interference, when the matters were fresh in mind.
An incident in connection with the purchase of Tesla’s motor inventions we deem corroborative. In 1887-88 Shallenberger, since deceased, was an electrical engineer and inventor in the employ of the Westinghouse Company. Independently he invented polyphase and split-phase motors. When Tesla’s polyphase patents of May 1st came *713to his notice he was grievously disappointed. On behalf óf his company he went to New York in June to look into the advisability of buying the Tesla inventions. The purchase, consummated on July 7th, included the polyphase patents, the application of May 15th for inductive split-phase motors, and the inventions of the patents in suit, for which applications were to be filed later. If Shallenberger had not been convinced by his investigation that Tesla had anticipated him in every feature of both sorts of rotating-field motors, it seems to us incredible that he should have failed to apply for patents and should have advised the purchase of the Tesla inventions.
There is no direct evidence to put into the opposite scale. Two negative circumstances are counted on by appellant to prove that Tesla’s story is false. Anthony was electrical engineer, expert, and inventor for the Mather Company of Manchester, Conn. He visited Tesla’s laboratory in January or February, 1888. Tesla was at Manchester in March with a view to interesting the Mather Company in the polyphase motor. On neither occasion did Tesla disclose to An-thpny that a rotating-field motor could be built that would operate when connected to a single-circuit line. Tesla says that he did not, because Brown had instructed him “not to give away any new ideas,” and to confine his explanations to the polyphase motors that were submitted to Anthony to test. The other circumstance is that he did not make an earlier disclosure to his attorney. But if he disclosed when Page says he did, the alleged anticipations fail. Tesla gives two reasons. One is that, if he told Page of the two-wire motor before the patents for the four-wire motor were completed, Page might think the two-wire motor of so much greater importance that he would not bestow the care on the patents in hand that he otherwise would. The other is that he delayed in telling his attorney in the belief that the two-wire motor patents would detract from the commercial value of the four-wire motor patents. It is only unexplained silences that support the argument that because Tesla did not tell he had not then produced the split-phase motors. And the argument is based on an inconclusive inference, for accomplishment and silence may coexist. We regard the explanations as probable. If improbable, the resulting inconclusive inference does not assail the credibility of Brown, Nellis, and Page. On the whole record we have no doubt that Tesla antedated Ferarris and Shallenberger.
■ The prior art, therefore, is limited to Tesla’s polyphase invention and to Overbeck’s demonstration. The polyphase invention, “considered in its essence, was the production of a continuously rotating or whirling field of magnetic forces for power purposes by generating two or more. displaced or differing phases of the alternating current, transmitting such phases, with their independence preserved, to the motor, and utilizing the displaced phases as such in the motor.” Westinghouse Co. v. Granite Co., 103 Fed. (C. C.) 951; Id., 110 Fed. 753, 49 C. C. A. 151. Overbeck had proven as a fact in the science of electricity that two alternating currents of differing phases could be obtained not only from two out-of-step sources of generation, but also Ay splitting a single current and inserting means of retardation in one ¿i the branches. The argument is that no invention was required to *714uncouple the motor of the May 1st patents from the four wires of the two-phase generator and then to couple up the same motor to the four wires that had been split from the single phase generator. By referring to the illustrations taken from appellant’s brief it will be seen that the assumption is made that the methods and means of the patents in suit resulted from the substitution above the line X, X, of the rotating-field motor of the patents of May 1st for Overbeck’s current-testing instrument. And the assumption is attempted to be justified by italicizing the words from the .specification, “I have, however, discovered another method of operating these motors, which dispenses with one of the line circuits and enables me to run the motors by means of alternating currents from a single original source.” ■
If the assumption were accepted, we should not be ready to deny invention. Patents are granted for advances in the useful arts, not for increments of knowledge. . On the basis of the assumption,, this case would not stand as a transference of useful means within an art, or from art to art; it would be art’s first application of an empirical teaching of science. Whether the accomplishments of the patents in suit would haye been developed under the hands of an ordinary workman skilled in the electric motor art, or whether they would have lain unknown unless first visualized in the imagination of an inventor, are questions concerning which the experts differ antipodally. If we had doubts as to which experts voice the saner view, the success and value of these improvements should face us towards invention.
But when the specifications, drawings, and claims are taken together and examined in connection with the actual conditions relating to the practical question of transmitting power by electricity, we think the assumption is entirely unwarranted. Before' the improvements of the patents in suit were made a power company could build a dam, put in turbines to run dynamos, and erect‘line wires to carry the current to consumers. By commutators at "the power plant the alternating could be converted into a one-way current, which would run direct-current motors. Their power and the radius within which they could be used were, quite limited. The synchronous alternating current, motors would not start on application of the current, and would not continue if their loads threw them out of synchronism with the generator. When Tesla devised the polyphase motor, meaning thereby the rotating-field motor whose motor circuits are of the same electrical character and value, it will be remembered that Brown’s objection in substance was that factory owners could not be expected to buy such motors unless and until power companies should reorganize their existing plants and put up additional sets of line wires. Though a power plant and line wires and a motor in a customer’s factory; when connected, may be viewed as a unit electrically, practically they are separate. The practical, the commercial problem that Tesla solved was to put on the market a rotating-field motor that consumers of electricity could purchase and attach to’ the single alternating current wires of a power plant." The polyphase and the split-phase are both rotating-field motors. In that sense, and in that sense only," is the italicized sentence from! the specification, when read with all the context, to be taken; for the, polyphase and the -split-phase motors differ from .each other *715radically. While the motor circuits of the polyphase must be of the same electrical character and value, the motor circuits of the split-phase must not be of the same electrical character and value. Take the split-phase motor of Fig. 6. To produce it a polyphase motor would have to be reconstructed by making one of the motor circuits of finer wire than the other. The same is true when copper is used for one motor circuit and German silver for the other. On examination it is found that every form of split-phase motor illustrated, described, and claimed in the patents in suit differs in the same way from the polyphase motor. Couple the two motor circuits of a split-phase motor to the line circuits from a two-phase generator, and, assuming the differences of phase in the motor circuits and in the line circuits to be the same, the split-phase motor will not work; the polyphase works in that connection, and in no other.
Finally, want of invention is urged from the fact that at about the same time Ferarris, Shallenberger, Anthony, and Jackson produced the same results in the same way. The argument involves the leveling of Tesla to a mechanic skilled in the electric motor art by assuming that the gentlemen named are of the mechanic rank. That Ferar-ris and competent patent authorities did not deem the assumption true as to him is proved by Ferarris’s applying for and taking out patents in European countries, and by his interferences with Tesla’s applications. Shallenberger obtained a patent on an electric-meter mechanism involving the split-phase principle. Apparently he thought this was all that was left open to him out of his independent inventions of the polyphase and split-phase motors. The tentative suggestion in the letter of Jackson, a university professor of physics, may be dismissed as a rebound from the disclosure in Anthony’s letter to, him. Anthony’s letter, March 11, 1888, is accepted as showing that he then comprehended, if he had not then practiced, the principles of the split-phase motors. His previous examination and study of Tesla’s polyphase motor induced, we believe, the train of thought and experiments which he now says did not involve invention. Iiis letter, however, leads us to conclude that he was of a different opinion at the time, and that he would have,applied for patents on split-phase motors had he not been restrained by a sense of professional honor. The contemporaneous opinions of these highly trained men we value as corroboration. We think they were right in ranking themselves inventors. And it is not unprecedented that the spirit of a particular period should bring forth within the same lines a galaxy of geniuses.
Our judgment on this record is that, to these unanticipated methods and means of producing a new and useful practical result, we cannot deny the quality of invention.
Was Tesla prevented from receiving and the government from granting the monopolies of the patents in suit by reason of the prior issuance of patent No. 401,520? The applications for the patents in suit were pending when the application for patent No. 401,520 was filed. The statute requires the applicant to point out clearly and to, claim distinctly the new thing of which he is asking a monopoly. These considerations must be borne in mind in examining the application which became patent No. 401,520. The specification and claims *716of this patent, as set forth in the statement, show that synchronous motors, polyphase motors, and split-phase motors were recognized as being then old in the art. Each form was therefore open to the use of the public so far as patent No. 401,520 was concerned. If some one was otherwise empowered to shut off the free use of synchronous motors or of polyphase motors or of split-phase motors, that was another matter. What was distinctly pointed out and claimed as new was a method of operating synchronous motors. One trouble with them had been that they were not self-starting. Tesla said: Take a synchronous motor; apply to it, for starting purposes, the rotating-field of either a polyphase or a split-pliase motor; when synchronism is attained, cut out the rotating-field, and there is the synchronous motor in full operation.
Counsel argue that, particularly in view of claim 5 and Eig. 7 of patent in suit No. 511,560 and of the parts of the specification relating to such. claim and figure, no invention was required to discover the method of patent No. 401,520, and therefore the invention that was covered by No. 401,520 was the invention now claimed under the patents in suit.
The variableness in the dephasing devices, described in No. 511,560, is for the purpose of regulating and reversing a split-phase motor. Differences of phase must be maintained if the split-phase motor is to operate. Motors, to be synchronous motors, must be supplied with single-phase current. Claim 5 and Eig. 7 have no “switch mechanism, by means of which the (full and unimpeded) line-current may be carried directly through the motor coils or indirectly through paths by which its phases are modified,” as is required in No. 401,520. But even if the mechanical combination necessary to the method of No. '401,520 were described in No. 511,560, invention may have been involved in prescribing the method of use claimed in No. 401,520. As the Supreme Court said in Carnegie Co. v. Cambria Co., 185 U. S. 403, 22 Sup. Ct. 698, 46 L. Ed. 968:
“If the mere fact that a prior device might be made effective for the carrying on of a particular process were sufficient to anticipate such process, the absurd result would follow that, if the process consisted merely of manipulation, it would be anticipated by the‘mere possession of a pair of hands.”
So, looking only collaterally at the question of inventiveness in the method of No. 401,520, we are not prepared to reject the presumption which is carried by the grant.
But if the premise that no invention was displayed in the method of No. 401,520 were true, the conclusion would not necessarily follow that some other invention was covered by that patent, and that such other invention was the invention described and claimed in the patents in suit. From what has already been said, our conclusion may be gathered that No, 401,520, whether good or bad, does not touch the patents in suit.
“Every patent granted for an invention which has been patented in a foreign country” shall expire at the same time with the foreign patent. The invention which was patented in British patent No. 6,527 of 1889, being the invention patented in No. 401,520, was not the invention for which the patents in suit were granted.
The decree is affirmed.