This is a patent case, under Section 145 of Title 35 U.S.Code (1952), 35 U.S. C.A. § 145. The Patent Office and District Court both found lack of invention over the prior art. On the record before us, we cannot say that either the Patent Office or the District Court erred. It may well be true, as plaintiff-appellant argues, that he has made a useful contribution to the art of die making. But the essence of any such contribution, as expressed in his brief and argument, is not reflected in the language of his formal claims, 1 or in any proof offered to the District Court.

Affirmed.