Volume indicator for anesthesia machine system

Claim 1

IN A LUNG VENTILATING SYSTEM HAVING CONDUIT MEANS FOR CONVEYING LUNG VENTILATING GASES TO AND FROM A PATIENT, A BELLOWS UNIT ARRANGED TO COLLAPSE AND EXPAND GENERALLY VERTICALLY AND WITH ITS INTERIOR IN COMMUNICATION WITH SAID CONDUIT MEANS AND PROVIDING FOR DEVELOPMENT OF PRESSURE IN THE CONDUIT MEANS BY A VERTICAL COLLAPSING STROKE OF THE BELLOWS UNIT FOR ASSISTING INHALATION BY THE PATIENT AND PROVIDING FOR VERTICAL EXPANSION OF THE BELLOWS UNDER THE INFLUENCE OF THE PATIENT''S EXHALATION, A CHAMBER SURROUNDING THE BELLOWS AND PNEUMATICALLY ISOLATED FROM THE INTERIOR OF THE BELLOWS UNIT DURING SAID COLLAPSING STROKE, THE CHAMBER HAVING A TRANSPARENT WALL THROUGH WHICH COLLAPSING AND EXPANDING STROKES OF THE BELLOWS ARE VISIBLE, A BAG ADAPTED TO BE MANUALLY SQUEEZED IN A HAND OF THE OPERATOR AND CONNECTED TO THE INTERIOR OF SAID CHAMBER TO EFFECT SAID COLLAPSING STROKE OF THE BELLOWS AND TO EXPAND UNDER THE INFLUENCE OF EXPANSION OF THE BELLOWS, THE BAG THEREBY BEING FREE TO TRANSMIT THE "FEEL" OF THE PATIENT''S BREATHING TO THE HAND OF THE OPERATOR, AND BREATHING VOLUME INDICATOR SCALE MEANS FOR READING THE BELLOWS COLLAPSING AND EXPANSION STROKES AS VISIBLE THROUGH THE TRANSPARENT CHAMBER WALL CONCURRENTLY WITH "FEELING" THE PATIENT''S BREATHING IN THE COLLAPSING AND EXPANSION OF THE BAG.