Countersink

—A conical rose bit or fluted reamer, for enlarging bolt holes to a conical rece for the reception of the tapered head of the bolt, which is thus, let into the material so that the bolt head is flush with the exterior surface. voup The two electrodes of a voltaic cell. 2. A pair of equal and parallel forces acting in opposite directions, tending to produce a motion of rotation in the body acted on.