Apparatus for determining the deviation of a borehole from the vertical axis

Claim 1

IN APPARATUS FOR DETERMINING THE ANGULAR DEVIATION OF THE LONGITUDINAL AXIS OF A WELL FROM THE VERTICAL AND THE AZIMUTHAL DIRECTION OF SAD DEVIATION, THE COMBINATION OF A HOUSING ADAPTED TO BE LOWERED INTO A WELL, MEANS CARRIED BY THE HOUSING FOR MAINTAINING THE LONGITUDINAL AXIS THEREOF IN FIXED RELATION TO THE LONGITUDINAL AXIS OF THE WELL, COMPASS MEANS HAVING A CONTINUOUSLY NORTH POINTING MOVABLE ELEMENT, UNIVERSAL JOINT MEANS SUPPORTING SAID COMPASS MEANS IN SAID HOUSING, FIRST ELECTRICAL CIRCUIT MEANS INCLUDING ELECTRICAL INDICATING MEANS AT THE SURFACE OF THE EARTH AND AN ADJUSTABLE ELEMENT COUPLED TO SAID COMPASS MOVABLE ELEMENT FOR VARYING A PARAMETER IN SAID FIRST ELECTRICAL CIRCUIT MEANS ACCORDING TO THE POSITIN OF SAID COMPASS MOVABLE ELEMENT RELATIVELY TO A REFERENCE POSITION, MEANS FOR IMPARTING RELATIVELY WEAK VIBRATIONS TO SAID COMPASS MEANS TO RENDER SAID COMPASS MOVABLE ELEMENT CONTINUOUSLY FREELY MOVABLE, A MEMBER MOUNTED FOR PIVOTING MOVEMENT IN SAID HOUSING ABOUT AN AXIS HAVING THE SAME DIRECTION AS THE LONGITUDINAL AXIS OF THE WELL, AN OFF-CENTER WEIGHT CARRIED BY SAID MEMBER, SECOND ELECTRICAL CIRCUIT MEANS INCLUDING ELECTRICAL INDICATING MEANS AT THE SURFACE OF THE EARTH AND AN ADJUSTABLE ELEMENT COUPLED TO SAID MEMBER FOR VARYING A PARAMETER IN SAID SECOND CIRCUIT MEANS ACCORDING TO THE ANGULAR POSITION OF SAID OFF-CENTER WEIGHT RELATIVELY TO A REFERENCE