Grindle

This is a suit for the declaration of invalidity of a patent, No. 2,534,644, and for certain relief incident to the invalidation of that patent, including damages and the assignment of the patent to the claimed true inventor. Jurisdiction arises under 28 U.S.C. § 2201 .

. The patent in question concerns a measuring device to determine the quantity of gasoline in the wing tanks of airplanes, known as a “dipstick.” The dipstick is a liquid fuel column gauge, of a type long familiar. A patent issued as long ago as May 26, 1863, to one Hyde (No. 38,681) for a “cask gauge” described the essentials of the gauge as being a tube or cylinder “made of transparent glass, or its equivalent, and left open at either end”, enclosed within the center of a square slitted rod “made of wood, metal, gutta-percha, or any other suitable material, so that either end of the rod shall be flush with the ends of the enclosed tube”, and with suitable gauging scales marked on the four sides of the enclosing rod, each adapted to a particular type of cask, so that by observing the level of the fluid in the central measuring tube, the content of the cask or vessel could be ascertained. The operation of the…