delivered the opinion of the Court:
This is an appeal from a decision of the Commissioner of Patents in an interference case, wherein the subject of controversy is an improvement in motor carriages propelled by steam. The invention is described in the following three issues formulated in the Patent Office:
“1. The combination with a carriage of a steam boiler carried thereby and having a burner for heating it, and a flue for disposing of the combustion from the burner, said flue having substantially horizontal divergent branches, which are provided with outlets to the atmosphere, and are arranged on either side of that portion of the flue which connects with the flues or heating passages of the boiler, said branches together forming a through passage for disposing of atmospheric currents which might otherwise reverse the normal draft of the burner.
*284“2. Tbe combination with a carriage body, of a steam boiler carried thereby and having a burner for heating it, and a flue for disposing of the products of combustion from the burner, said flue having substantially horizontal divergent branches extending transversely of the carriage body and terminating in outlets to the atmosphere which coincides substantially with the planes of the side walls of the carriage body, said branches being arranged on either side of that portion of the flue which connects with the flues or heating passages of the boiler, and together forming a through passage for disposing of atmospheric currents which might otherwise reverse the normal draft of the burner.
“3. The combination with a carriage, of a steam boiler carried thereby and having a burner for heating it, and a substantially horizontal flue at the top of the boiler for disposing of the products of combustion from the burner, said flue having a middle or enlarged part immediately covering the boiler and a transverse part disposed to the rear of said middle or enlarged part and consisting of divergent branches having outlets to the atmosphere, and together forming a through passage for disposing of atmospheric currents which might otherwise reverse the normal draft of the burner.”
The invention, as is apparent, consists in the mode of construction of the smoke outlet of steam carriages, and is practically no more than the application to steam carriages of a cowl or chimney top, so as to give the chimney the shape of the letter T.
The appellee Mudge has a patent for the invention issued to him on September 18, 1900, upon an application filed April 30, 1900. Lemp did not file his application until July 27, 1901, more than ten months after the issue of the patent to Mudge. In his preliminary statement Lemp claims conception of the invention on or about April 17, 1899; a reduction to practice of the invention described in counts 1 and 3 of the issue about April 19, 1899 ; and a reduction to practice of the invention of count 2 of the issue on or about August 30, 1899. In kludge’s preliminary statement the allegation was of conception and disclosure of the invention about September 1, 1899, and of its reduction to practice about February 1, 1900.
*285Tbe Examiner of Interferences, upon tbe testimony adduced in tbe case, beld in favor of Mudge, tbe patentee, bere tbe appellee. Tbe Board of Examiners-in-Chief beld in favor of Lemp; but the Commissioner of Patents reversed tbe decision of tbe Board of Examiners, and awarded judgment of priority of invention to tbe patentee, Mudge. Erom bis decision tbe case comes to us on appeal.
Notwithstanding tbe favorable decision thereon of tbe Board of Examiners-in-Cbief in tbe Patent Office, we must regard tbe claim of the appellant as wholly without merit. To our minds bis is as clear a case of an unsuccessful and abandoned experiment as could well be conceived. It appears from bis testimony that in April of 1899 be did make some bind of cap for bis flue of tbe nature of tbe invention bere in issue, but that it was discarded and relegated to tbe scrap heap after a few trials within a month and a half after it was put on, and that it was never again used; that in August or September of 1899 be constructed and used a longer cap or cowl, but that this also was very soon discarded and relegated to tbe scrap heap, and never again used; that it does not appear that either one of these devices was ever successfally operated; and that nothing whatever was. done to utilize either until bis application was prepared and filed in this case 10 months after tbe issue of tbe patent to Mudge. Only upon reading this patent did be recall tbe fact that be thought be bad tbe same device some years before. This is not an unusual idea under such circumstances. But claims of this character, advanced under such circumstances, must be proved by testimony of tbe clearest and most satisfactory character before they can be accepted.
Tbe appellant bere, being tbe junior applicant and having to overcome a patent in tbe bands of bis adversary, is required to establish bis case by proofs which admit of no reasonable doubt. Kelly v. Fynn, 16 App. D. C. 573; Dashiell v. Tasker, 21 App. D. C. 64. Instead of so establishing bis case, be has failed even in showing that be ever bad tbe invention in issue. He certainly never reduced it to practice; and bis total abandonment of it, notwithstanding that there was constant and incessant need for *286some suck device, is proof positive to our minds tkat kis contrivance was no more tkan it plainly appears from kis own testimony to kave been, — an unsuccessful and abandoned experiment.
It is unnecessary to go further into tke case. Tke Commissioner’s opinion, as we find it in tke record, is full and conclusive; and we would add notking to it. We tkink tkat tke appellee, kludge, is entitled to judgment of priority of invention; and tke Commissioner’s decision to tkat effect is therefore affirmed.
Tke clerk of tke court will certify this opinion and the proceedings of tke court in tke premises to tke Commissioner of Patents according to law. Affirmed.