temper-screw

Century Dictionary and Cyclopedia

1. n. In well-boring, the connecting-link between the working-beam and the cable, which is let out as fast as the drill penetrates the rock, so as to regulate the play of the jars. When the whole length of the screw is run out, it is disengaged and carried up, so as in a few minutes to be ready for another run. See cut under oil-derrick.
2. n. A set-screw the point of which bears against an object or a bearing, and serves to adjust it.