Cartesian diving element for cartesian toys

Claim 1

A CARTESIAN DIVING ELEMENT, COMPRISING: A BODY ADAPTED TO SUBMERGED IN A LIQUID AND INCLUDING A SEALED VARIABLE BUOYANCY CHAMBER HAVING A MOVABLE PRESURE RESPONSIVE WALL EXPOSED TO THE EXTERIOR OF SAID BODY FOR MOVEMENT OF SAID WALL TO VARY THE EFFECTIVE LIQUID DISPLACEMENT VOLUME OF THE BODY IN RESPONSE TO CHANGES IN THE EXTERNAL LIQUID PRESSURE ON THE BODY, A RIGID, EXTERNALLY ACCESSIBLE, LIQUID-DISPLACEMENT-VOLUME ADJUSTING WALL MEMBER MOUNTED ON SAID BODY IN FLUID SEALING RELATION TO THE BODY AND EXPOSED TO THE EXTERIOR OF THE BODY OF VARYING THE EFFECTIVE LIQUID DISPLACEMENT VOLUME OF SAID BODY INDEPENDENTLY OF SAID PRESSURE RESPONSIVE WALL AND THE EXTERNAL PRESSURE ON THE BODY, MEANS ISOLATING SAID PRESSURE RESPONSIVE WALL FROM SAID RIGID WALL MEMBER, WHEREBY ADJUSTMENT OF SAID WALL MEMBER IS INEFFECTIVE TO ALTER THE INTERNAL PRESSURE ON SAID PRESSURE RESPONSIVE WALL, MEANS FOR RETAINING SAID RIGID WALL MEMBER FIXED IN ADJUSTED POSITION, SAID PRESSURE RESPONSIVE WALL AND SAID RIGID WALL MEMBER BEING EFFECTIVE CONJOINTLY TO VARY THE EFFECTIVE LIQUID DISPLACEMENT VOLUME OF SAID BODY OVER A GIVEN RANGE, AND SAID BODY BEING WEIGHTED TO RISE IN SAID LIQUID WHEN THE EFFECTIVE LIQUID DISPLACEMENT VOLUME OF THE BODY FALLS WITHIN ONE PORTION OF SAID RANGE AND TO SINK IN SAID LIQUID WHEN THE EFFECTIVE LIQUID DISPLACEMENT VOLUME FALLS WITHIN ANOTHER PORTION OF SAID RANGE.