delivered the opinion of the Court:

This appeal is from the decision of the Commissioner of Patents in an interference proceeding awarding priority of invention to appellees, Charles A. Kraus and Roy D. Mailey, for a vapor electric apparatus.

The issue is sufficiently set forth in the following counts.

“1. A vapor converter comprising a conducting casing, and a vaporizable electrode within and insulated from the casing.”

*257“3. A vapor converter comprising a conducting casing, a vaporizable electrode within and insulated from the casing, a conductor projecting from one side of the casing into the vaporizable electrode at the opposite side thereof, and an insulating sheath for said conductor.”

“5. A vapor converter comprising a conducting casing, a vaporizable electrode within and insulated from the casing, a conductor projecting from one side of the casing into the vaporizable electrode at the opposite side thereof, and an insulator surrounding the conductor, and separating it from the casing, and also extending into the vaporizable electrode.”

“12. In a vapor electric apparatus, a closed metal container, anodes suspended therein, a mercury cathode and a cup to contain the latter composed of insulating material lodged in the bottom of the container.”

The tribunals of the Patent Office have unanimously held that appellant, Prank Conrad, has not shown a reduction of the invention to practice prior to his filing date. With this ruling we agree. lie was accorded a date of conception not later than January, 1909, but he did not file his application until December 10, 1910. For three years he was engaged in experimental work, with all the facilities of the Westinghouse Electric Company, his assignee, at his command. The case turned below on the question of appellant’s lack of diligence. The Commissioner held that he had not been diligent, and awarded priority to appellees. We have examined the evidence with care, and have reached a conclusion in accord with the Commissioner’s decision.

The decision of the Commissioner of Patents is affirmed, and the clerk is directed to certify these proceedings as by law required. Affirmed.