Bettis

Appellant brought this action alleging an infringement of patent No. 1,573,031 for a “well casing protector.” The patented device is for use in connection with a rotary drill for oil wells, and is designed to protect the metal "well casing from contact with the metal drill pipe and couplings by the interposition-of a rubber buffer. The vibration of the drill pipe during drilling causes such contacts and the consequent injury to the easing and the drill pipe. Such contacts also result from the crookedness of the well and the fact that the drill pipe and the well easing are not concentric, at some-points resulting in friction at the points of contact between the drill pipe 1^s projecting couplings-and the inner 0Uíí?e0 ^ casin& S3^ i*1 drilling mud tending to wear out the contact- ^ metal surfaces. The patented device consists simply of a baM ^ or other resilient material, with an interior diameter smaller than the exterior diameter of the drill pipe for gripping the drill pipe tenaciously by reason of its elasticity with an exterior diameter greater than that of the pipe couplings, although more elaborately described in the patent. As the pipe vibrates in the well, tbe mbber…