delivered the opinion of the Court:
Sarfert, as the junior applicant, is chargeable with the burden of proof. The fact that his opponent Meyer holds a patent, imposes the burden on him to prove his case beyond a reasonable doubt. This he does if he proves his dates conclusively, as set forth in his preliminary statement: for these dates are all prior to the time which Meyer claims as that of his conception of the invention: unless, indeed, Sarfert’s delay in applying for a patent has the result of affecting his right.
The case is one merely of the weight of testimony. There is an “ Exhibit A” in the case, being a machine constructed by Sarfert, which, by written stipulation, is conceded to be a reduction of the invention to practice by Sarfert, and which is amply proved even without the stipulation. Its date, however, is not shown by the stipulation. There is also a stipulation to the effect that about June 14, 1898, Meyer constructed a machine wherein he reduced the invention to practice. But Sarfert’s Exhibit A is shown by testimony, which is indisputable and which places the fact beyond all question, to have been constructed as early as March, 1898. It necessarily follows that Sarfert’s conception of the invention and its reduction to practice by him both antedated Meyer’s conception, for which he himself claims no earlier date than April of 1898.
There is the usual claim of inoperativeness of Exhibit A, the absence of some of the component members, and other *29defects. But we think that all these considerations have been satisfactorily disposed of by the Commissioner in his opinion, as well as by the other tribunals of the Patent Office in their respective decisions. We deem it unnecessary and would regard it as useless to add to the review of the testimony which they have so well analyzed and discussed.
It is argued that Sarfert concealed his invention, and that his case therefore should be governed by the decision in Mason v. Hepburn, 13 App. D. C. 86. It is true that he may have concealed it for a little time; but it is very plain that he soon gave it to the public in the way of the result of its operation, and that he showed it to his opponent Meyer early in 1899. This is inconsistent with the theory of suppression of the invention to which effect was given in the case of Mason v. Hepburn.
On the whole, we think that the Commissioner and the other tribunals of the Patent Office were right in the conclusion reached by them in this case. The decision of the Commissioner, awarding judgment of priority of invention to the appellee Sarfert, will therefore be affirmed.
The cleric of the court will certify this opinion, and the proceedings in the cause in this court, to the Commissioner of Patents according to law.