delivered the opinion of the Court:
In view of this condition of the record, we are not sure that we have jurisdiction to determine the issue in this case. The authority conferred on this court by the act creating it is, in reference to interference cases appealed to it from the decision of the Commissioner of Patents, to review the action of the Commissioner determining the right of priority of two or more persons claiming the same patentable invention. In the sense of the patent law there can be no interference unless there is patentable invention and there are rival claimants of it. Patentability of the invention or device is' a necessary prerequisite to a declaration of interference; and the patentability of an invention, in controversy, except under some extraordinary circumstances, is not an open question before us. It is necessarily assumed in the declaration of interference, and the parties are estopped from,denying it. It would be absurd and inconsistent to make application for a patent for an alleged invention, and immediately thereafter, *259when some one else claims the same invention, to argue against its patentability.
We understand the rules and the practice of the Patent Office to be in accordance with this requirement of law and right reason; and that no interference is ever declared between parties until there has been an adjudication of patent-ability. The absurdity of a declaration of interference, with a reservation at the same time of the question of patentability for future adjudication, would be, so far at least as this court is concerned, too glaring to be tolerated. Of course, it is always possible that, even after a prima facie adjudication of patentability, facts may be disclosed, in the course of interference proceedings or otherwise, which would make it the duty of the Patent Office to refuse a patent, notwithstanding the preliminary adjudication. And it may be admitted that, until the patent is actually issued, it is always competent for the Patent Office, with due regard to the rules of law, to vacate its adjudication for good and sufficient cause. But that there must be an adjudication of patentability, final to all ordinary intents and purposes, before this court can be called upon to determine the right of ownership as between rival claimants, we must regard as the demand of the statute. Otherwise, we would be trying moot causes, which it is not the province of any court of justice under our judicial system to try; or else we would be called upon to perform duties which are not judicial in their nature, and which, under our system of government, it is not competent for the legislature to impose upon judicial tribunals.
In the case now before us there would seem to be no final and definite adjudication of patentability of the invention or device in controversy. It is true that the primary examiner has passed upon it, and has adjudged it to be patentable. But the board of examiners has expressed a different opinion; and while that opinion has not the effect, under the circumstances and the rules of the Patent Office, of overruling the primary examiner, and the board can only call the attention of the Commissioner to the matter, which it has done, yet the Commissioner has virtually adopted the *260suggestion, and has held the question of patentability in abeyance to be reconsidered by the primary examiner when the matter goes back to him.
It is, of course, competent for the Patent Office to regulate its business in its own way, and to determine for itself by its own rules when and in what order it will take up the questions which arise in the performance of its functions. But, as we have said, this court cannot be called upon to determine moot causes; and the present is no more than a moot cause, since upon the face of the record itself the question of patentability bas been expressly reserved for further and future consideration.
Tbis question, however, bas not been raised by either of tbe parties to tbe cause; but, as it very greatly affects our jurisdiction, we are compelled to raise it ourselves, and to suggest tbe grave doubt wbicb exists in our minds whether we can assume jurisdiction in eases like tbe present.
But assuming that we bave jurisdiction, we do not see wbat there is here for us to adjudicate. Tbe appellant bas distinctly and in tbe most positive manner, in tbe course of bis testimony in tbe cause, disclaimed all interest in tbe subject-matter of controversy. Upon bis examination as a witness on bis own behalf, tbis question was deliberately propounded to him by bis own counsel:
“ Do you claim to be tbe inventor of a device or mechanism embracing tbe particular combination of parts or elements specified in tbe issue of interference, as you understand them ? ”
And bis deliberate answer to tbe question was —
“I do not.”
Now we do not see tbe necessity or propriety of seeking to force upon a man tbe paternity of an invention which be - so positively repudiates. In all probability tbis statement was made for tbe purpose of procuring a dissolution of tbe interference; but it matters not wbat tbe purpose of tbe appellant was in making it. It is a positive declaration under oath that be never was tbe inventor of tbe matter in issue. •This we think should settle tbe controversy. Taken in con*261nection with the appellant’s contention before the Patent Office that the device of the claim was not patentable, it would show quite conclusively that the purpose of the appellant was rather to defeat his opponent than to procure a patent for himself.
Were we to go farther and to disregard this disclaimer of interest on the part of the appellant, we would still find that Pelbel was the. first and original inventor in this case, and not Oliver.
That Felbel’s conception of the invention and all that he did in the way of reduction to practice antedated the conception of Oliver by several months, is abundantly proved, and we understand that it is not even contested by Oliver. But for the reason that Felbel was not diligent in coming to the Patent Office with an application, or in putting the invention on the market, and that in the meantime Oliver did put the invention on the market and promptly applied to the Patent Office for a patent, it is sought to bring this case within the ruling in Mason v. Hepburn, 13 App. D. C. 86, and Warner v. Smith,, 13 App. D. C. Ill. We, however, concur with the Commissioner of Patents and the other tribunals of the Patent Office in holding that this case falls rather within the ruling in the cases of Esty v. Newton, 14 App. D. C. 50; McBerty v. Cook, 16 App. D. C. 133, and the more recent case of Roe v. Hanson at the last term of this court. 19 App. D. C. 559. There was here no fraudulent concealment, no suppression of the invention to keep it from the public, no abandonment of it as of an unsuccessful experiment, no such unreasonable delay as to impose upon the claimant the burden of proof beyond a reasonable doubt. On the contrary, Felbel’s delay in this instance does not seem to have been unreasonable under all the circumstances. He had placed his invention in the hands of the person to whom it was most natural for him to look to manufacture it for commercial use, which he was unable to do himself; and he withdrew it from him as soon as it became apparent to him that this person was not then disposed to take up the matter. He had constructed a practical'operative *262machine; the reduction to practice had been complete; and all that remained to be done for the security of his right was to make his application for a patent. Undoubtedly it was' possible for him to have done this more promptly than he did; but the delay was not unreasonable.
The diligence required of an inventor is diligence rather in the reduction of his invention to practice than in application to the Patent Office or in manufacturing his device for public use. It is very true, as we held in Mason v. Hepburn, Warner v. Smith, and other cases, that delay long and unexplained, and yielding to activity only when the knowledge comes of the entrance of a rival on the field, is always presumptive evidence that what is claimed to have been reduction to practice was no more in fact than an unsatisfactory or abandoned experiment. But when reduction to practice has been satisfactorily shown, and there is no unreasonable or unexplained delay, there is no law that would bar the first or original inventor of his right. In order to give to delay the effect of destroying such a right, there must be some circumstance of concealment, suppression or abandonment of the invention.
Notwithstanding our intimation that this cause, as now presented, is not ready for the appellate action of this court, we have deemed it proper to state our opinion upon the merits in view of the fact that neither party has raised the question of jurisdiction and we desire under the circumstances to save them the expense and delay of another appeal. Upon the merits, assuming the question of patentability of the alleged invention to have been definitely solved, we think that there was no error in the decision of the Commissioner of Patents.
In cases of this kind we think the proper practice to be, that the Commissioner, reserving, if he so desires, the determination of the question of interference, should hold the cause until he has referred the question of patentability back to the examiner and there has been a definite adjudication of this latter question. Then, and not until then, his deter*263mination of the issue of interference would present a cause for our cognizance.
The clerk of the court will certify this opinion, and the proceedings in this court in the premises to the Commissioner of Patents, according to law.