Abstract: A magnetic compass including a flexible bowl having a rim with an annular inwardly facing groove. The inwardly facing groove is adapted to engage a flange of a transparent cover in a tight sealing relationship, the combined assembly enclosing a compass rose.

Abstract: A wrench is disclosed which provides a readout of its angle of rotation by means of an inertial body mounted in a housing affixed to the wrench. Manual and automatic means are provided for determining the rotation of the housing with respect to the body.

Abstract: Disclosed herein is a wrench-type hand tool having apparatus for indicating the magnitude of the tightening angle through which the tool is rotated about an axis through a workpiece when applying a torque to the workpiece. The apparatus comprises a gyroscope having a rotor defining a spin axis mounted upon the tool for rotation therewith. The spin axis is oriented substantially transversely to the axis of the workpiece. Means are provided for determining the magnitude of precession of the gyroscope rotor, so that the magnitude of the tightening angle can be indicated as a function of the time integral of the magnitude of precession.

Abstract: An improved device for measuring the tightening angle on a wrench. The directionally fixed member is a liquid body which may include solid particles or a turbine wheel, the relative velocity of which is monitored to determine the relative motion of the liquid with respect to the wrench.