Keszthelyi

' This is an appeal from a final decree of the District Court in favor of appellees in a suit in equity for infringement of letters patent No. 1,474,905 issued to appellant on November 20, 1923, for a new and useful improvement in tool joints used in rotary drilling of oil wells.

In his patent specifications appellant explains that in rotary drilling the bit cutting the formation is carried at the lower end of the string of drill pipe; that in order to withdraw the bit for sharpening or replacement, it is necessary to pull up the drill pipe, uncoupling it at intervals usually of three or four lengths of the pipe, for convenience in handling; that it is therefore necessary to provide a tool joint at such intervals to prevent injuring the threads of the pipe by frequent coupling and uncoupling; that one of the operations in rotary drilling is to pump a stream of mud laden fluid down through the drill pipe and through the bit, and to do this it' is necessary to apply considerable pressure at the upper end of the drill pipe so that in the ordinary type of tool joint it is difficult to insure tight joints which will withstand the pressure necessarily applied; that tool joints as…