
    FILTERITE CORPORATION, a body corporate of the State of Maryland, Appellant, v. TATE ENGINEERING, INC., and the Carborundum Company, Appellees.
    No. 15379.
    United States Court of Appeals, Fourth Circuit.
    Argued May 14, 1971.
    Decided May 27, 1971.
    Harry John Staas, Washington, D. C., Z. Townsend Parks, Jr., Baltimore, Md., for appellant.
    William H. Webb, Pittsburgh, Pa., for appellees.
    Before SOBELOFF, Senior Circuit Judge, and WINTER and CRAVEN, Circuit Judges.
   PER CURIAM:

Filterite Corporation, assignee of United States Letters Patent No. 3,356,-226, brought this action alleging infringement of its patent. The District Court, 318 F.Supp. 584, held the patent valid, but not infringed because of differences between the method of construction of the accused filter units and the specifications of the patent claim. Upon careful consideration of the record, the briefs, and oral arguments, we affirm the judgment of the District Court.

Affirmed.  