Adjustable foot piece

Claim 1

AN ANGULARLY ADJUSTABLE BASE STRUCTURE ADAPTED TO BE SECURED TO A SUPPORTING SURFACE COMPRISING: A SEAT ELEMENT HAVING A CONCAVE UPPER SURFACE; A BEARING MEMBER HAVING CONVEX UPPER AND LOWER SURFACES, SAID LOWER SURFACE OF SAID BEARING MEEMBER SLIDABLY SEATING ON SAID UPPER SURFACE OF SAID SEAT ELEMENT; A LEG SECURED TO SAID BEARING MEMBER; A COVER PLATE FOR SAID SEAT ELEMENT AND BEARING MEMBER HAVING A CONCAVE LOWER INNER SURFACE SEATINF AGAINST SAID UPPER SURFACE OF SAID BEARING MEMBER AND SLIDABLY ROCKABLE THEREABOUT; SAID COVER PLATE HAVING A CENTRAL CLEARANCE OPENING ABOUT SAID LEG TO PERMIT ITS ECCENTRIC MOVEMENT WITH RESPECT TO SAID LEG; THE PERIPHERAL PORTIONS OF SAID COVER PLATE EXTENDING DOWNWARDLY TO ENCLOSE SAID SEAT ELEMENT AND BEARING MEMBER, SAID PERIPHERAL PORTIONS, WHEN SAID COVER PLATE IS SEATED ON SAID BEARING MEMBER, BEING SPACED FROM SAID SUPPORTING SURFACE; FASTENER ELEMENTS FOR SECURING SAID COVER PLATE TO SAID FLOOR AND FORCING SAID COVER PLATE AGAINST SAID BEARING MEMBER AND SAID BEARING MEMBER AGAINST SAID SEAT ELEMENT FOR LOCKING THEM AGAINST MOVEMENT WITH RESPECT TO EACH OTHER.