Chicago Pneumatic Tool Co. v. Keller Pneumatic Tool Co.

RUNYON, District Judge.

These cases have to do with improvements in pneumatic hammers, and concern an art which was introduced to the attention of this court many years ago, when the primary patents issued to Boyer, now long since expired, were the subject of consideration, and through other cases reported as hereafter noted. Since those early days, these tools have come into such extensive use, and have been the subject of such varied and successful improvements from time to time, as to make the present art a highly developed one, and with a consequent shrinkage in the scope of possible…