H. Wenzel Tent & Duck Co. v. White Stag Mfg. Co.

The H. Wenzel Tent & Duck Co., hereafter called plaintiff, brought suit against the White Stag Manufacturing Co., hereafter called defendant, for allegedly infringing plaintiff’s patent on a self-cooling cotton canvas water bag. Defendant interposed by way of defense evidence as to its claimed manufacture and sale to the public of a substantially identical product more than one year prior to plaintiff’s original patent application. The district court held that since 1940, more than one year before plaintiff’s original filing date, there had been “a public use and a disclosure to the public that cotton fabric treated with paraffin to restrict the passage of water through the fabric without rendering the fabric entirely waterproof could be used in place of flax canvas in making self-cooling water bags”, and that plaintiff’s patent had been anticipated by prior public use and was “inadvertently granted”. Judgment was awarded to defendant, and plaintiff appealed.

It has long been known that water in a porous container can be kept cool by the limited seepage and evaporation of the water from the outer surface of the container. A flax bag soaked for twenty-four hours has proved to' be…