Concealed adjustment mechanisms for adjustable furniture

Claim 1

IN AN ARTICLE OF FURNITURE, A BACK THAT CAN BE TILTED FORWARDLY AND REARWARDLY, ARMS CONNECTED TO THE SAID BACK SO THAT SAID ARMS CAN MOVE FORWARDLY AND REARWARDLY AND REARWARDLY AS THE SAID BACK IS TILTED FORWARDLY AND REARWARDLY, SAID ARMS CONSISTING OF INNER PIECES AND OUTER PIECES, BRACKETS, PIN CARRIED BY SAID BRACKETS, SLOTS AND NOTCHES IN THE INNER FACES OF SOME OF SAID PIECES, SAID SLOTS AND SAID NOTCHES FREELY ACCOMMODATING SAID PINS, SAID NOTCHES AND SAID PINS BEING ENGAGEABLE TO LOCK SAID ARMS AND SAID BACK AGAINST MOVEMENT, SAID SLOTS AND SAID PINS BEING REGISTRABLE TO PERMIT MOVEMENT OF SAID ARMS AND OF SAID BACK, SAID PIECES OF SAID TWO-PIECE ARMS BEING GENERALLY SQUARE IN CROSS SECTION, SAID PIECES OF SAID TWO-PIECE ARMS BEING SPACED APART IN SIDE-BY-SIDE RELATION TO DEFINE GAPS THAT ACCOMMODATE SAID EXTENSIONS BUT THAT ARE NARROWER THAN THE THICKNESS OF A USER''S FINGER.