Angularly adjustable drafting tables

Claim 1

IN A MECHANISM FOR MOVING A MEMBER SUCCESSIVELY IN OPPOSITE DIRECTIONS UPON SUCCESSIVE MOVEMENTS OF ANOTHER MEMBER IN A SINGLE DIRECTION, SAID MECHANISM COMPRISING: A BASE; AN OPERATING LEVER PIVOTED AT ONE END ON SAID BASE; MEANS URGING SAID LEVER IN ONE ROTATIVE DIRECTION; AN ANGULARLY POSITIONABLE MEMBER PIVOTED TO SAID BASE, SAID POSITIONABLE MEMBER HAVING A PAIR OF PROTRUDING LUGS SUBSTANTIALLY EQUIDISTANT FROM ITS PIVOTAL AXIS; AND A POSITIONING ELEMENT PIVOTALLY ATTACHED TO SAID LEVER AND HAVING CAMMING SHOULDERS SLOPING TOWARD EACH OTHER FROM OPPOSITE EDGES OF SAID ELEMENT IN A DIRECTION GENERALLY AWAY FROM SAID ELEMENT''S AXIS OF ROTATION TO AN INTERVENING NECK, SAID EDGES PROTRUDING OUTWARD BEYOND SAID NECK TO FORM HOOKS WHICH INDIVIDUALLY ACT UPON MOVEMENT OF SAID LEVER AGAINST THE ACTION OF SAID MEANS TO PULL ON WHICH EVER LUG IS THEN MOST REMOTE FROM SAID ELEMENT''S ROTATIONAL AXIS, THUS ROTATING SAID MEMBER TO ANGULAR POSITION IN WHICH THE OTHER LUG WILL NEST UNDER THE OTHER HOOK, EACH OF SAID LUGS INDIVIDUALLY ACTING UPON UPWARD MOVEMENT OF SAID ELEMENT UNDER ACTION OF SAID MEANS TO SLIDE OUTWARD AND DOWNWARD ALONG THE THEN ENGAGING SHOULDER AND EXERT A TURNING MOMENT THEREON TO ROTATE SAID MEMBER TO AN ANGULAR POSITION IN WHICH THE OPPOSITE LUG WILL NEST AGAINST SAID NECK.