Douglass

This appeal presents the question whether the estoppel running against an assignor of a patent to assert its invalidity extends to third persons who acquire by purchase other and later patents of the assignor found to infringe the assigned patent. We think in the present state of the law the question must be answered in the negative.

Ralph M. Keele made application for patent for a hair waving device and simultaneously for a valuable consideration assigned the application to appellee. On December 18, 1934, letters patent No. 1,984,585 issued to appellee on the application. Subsequently Keele devised another method and apparatus for hair waving, known as Koolerwave, and shortly afterwards entered into an agreement with Tomlinson I. Moseley for the promotion of this method, assigning a one-half interest therein to Moseley in consideration of the latter’s agreeing to finance the development and patenting thereof. After a period of experimentation and development Keele applied for patents covering the device, and patents Nos. 2,187,473 and 2,187,474 were issued. In October, 1936, Keele and Mosely formed the Keelmo Company, and the two patents last above referred to (then in the form…