Crowell

Preliminary Statement.

The appellee manufactures and sells tools used in drilling and cementing oil wells; the appellant is an inventor, owning several patents of appliances and methods of cementing oil wells. The appellant claimed that the appellee manufactured and sold four types of apparatus, known as Baker Cement Retainers Model F and Model K, Baker Multiplex Cementing Equipment, and Baker Series Cementing Equipment, and that said apparatus and the method of its use infringed three of appellant’s patents; all of which the appellee denies.

To bring the controversy to a head the appellee brought this action against appellant for a declaratory judgment. The appellant denied the allegations of the complaint that appellant’s patents were invalid and were not infringed by appellee’s devices. The appellant also counterclaimed alleging that its patents were valid and were infringed by appellee. The appellee then in turn denied the counterclaiming allegations of infringement and reasserted the invalidity of the appellant’s patents.

The appellant’s patents involved herein are: No. 2,168,735, having twenty-three claims, a method patent which was issued to appellant Crowell as assignee…