This appeal is from the judgment of the District Court in a declaratory judgment proceeding that the appellants’ patent 1 was invalid “for lack of invention”. The District Court specifically found as a fact that the principles involved in the patent constituted “an improvement upon checker work then in use in the trade” but that they were the product of mechanical skill and not the product of inventive genius. We have examined the briefs and the record in this case and have carefully considered the arguments of the appellants. We are convinced that the findings of the District Court are amply sustained by the evidence. We need add nothing to what has been so well stated by Judge Clary in his exhaustive analysis of the evidence and the applicable law and accordingly the judgment of the Court below will be affirmed upon his opinion. 98 F.Supp-. 710.