Measurement of expired tidal air volume

Claim 1

APPARATUS FOR THE MEASUREMENT OF PULMONARY TIDAL VENTILATION COMPRISING A VERTICALLY DISPOSED TANK MEMBER HAVING A BOTTOM WALL AND BEING OPEN AT THE TOP, INTAKE AND EXHAUST TUBES EXTENDING UPWARDLY FROM THE LOWER PORTION OF SAID TANK AND TERMINATING IN THE UPPER PORTION THEREOF, MEANS CONNECTED TO THE LOWER END OF SAID INTAKE TUBE FOR CONDUCTING TIDAL EXPIRATION FROM A PATIENT TO SAID INLET TUBE, INTAKE AND EXHAUST VALVES CONNECTED TO SAID TUBES RESPECTIVELY FOR OPENING AND CLOSING THE SAME, SAID INTAKE VALVE BEING NORMALLY IN CLOSED POSITION AND BEING MOVABLE TO AND MAINTAINED IN OPEN POSITION BY THE IN-FLOW OF TIDAL EXPIRATION AND RETURNING TO CLOSED POSITION UPON CASSATION OF SUCH IN-FLOW, MOTION TRANSMITTING MEANS CONNECTING SAID INTAKE AND EXHAUST VALVES FOR OPERATING THE SAME ALTERNATELY IN UNISON, A DIVING BELL MEMBER MOUNTED FOR VERTICAL MOVEMENT IN SAID TANK MEMBER AND ENCLOSING THE AREA ABOVE THE UPPER ENDS OF SAID TUBES, A VOLUME OF WATER IN SAID TANK MEMBER FORMING A WATER SEAL FOR THE LOWER OPEN END OF SAID DIVING BELL, ONE OF SAID MEMBERS BEARING INDICIA, AND THE OTHER MEMBER HAVING A PORTION COOPERABLE WITH SAID INDICIA FOR INDICATING THE TIDAL VOLUME OF SUCH IN-FLOW.