Apparatus for specific gravity measurements

Claim 1

IN COMBINATION, A CONTAINER FOR A LIQUID, A MEMBER, MEANS LOCATING SAID MEMBER IN LIQUID IN THE CONTAINER AND MOUNTING IT FOR VERTICAL MOVEMENT UNDER THE BUOYANT ACTION OF THE LIQUID, SAID MEANS PROVIDING SUBSTANTIALLY NO RESTRAINT TO SAID MEMBER AGAINST VERTICAL MOVEMENT IN A LIMITED RANGE, ELECTROMAGNETIC MEANS OF BALANCEABLE MAGNETIC CIRCUIT TYPE PROVIDING AN ELECTRICAL SIGNAL OF RELATIONSHIP OF THE POSITION OF SAID MEMBER TO A PREDETERMINED POSITION THEREOF WITHIN SAID LIMITED RANGE, PHASE SENSITIVE MEANS RECEIVING SAID SIGNAL AND PROVIDING A REVERSIBLE DIRECT CURRENT OUTPUT INDICATIVE OF THE POSITION OF SAID MEMBER RELATIVE TO SAID PREDETERMINED POSITION, MEANS POSITIONABLE BY SAID OUTPUT AND REVERSIBLE THEREWITH IN ACCORDANCE WITH THE LAST MENTIONED POSITION, ELECTROMMAGNETIC MEANS FOR APPLYING DIRECTLY TO SAID MEMBER A VERTICAL MAGNETIC FORCE BALANCING THE BUOYANT ACTION OF THE LIQUID TO LOCATE SAID MEMBER SUBSTANTIALLY IN SAID PREDETERMINED POSITION, AND MEANS INDICATING THE MAGNITUDE OF SAID FORCE WHEN THE MEANS POSITIONABLE BY SAID OUTPUT HAS A POSITION CORRESPONDING TO THE LOCATION OF SAID MEMBER IN SAID PREDETERMINED POSITION, SO THAT THE INDICATION OF THE MAGNITUDE OF SAID FORCE AT THAT TIME IS A MEASURE OF THE SPECIFIC GRAVITY OF SAID LIQUID.