Double tube manometer to calibrate pressure sensing instruments

Claim 1

IN A CALIBRATING DEVICE, THE COMBINATION COMPRISING A DOUBLE SLANT TUBE MANOMETER INCLUDING A MEASURING TUBE AND A CORRECTION TUBE, SAID MEASURING TUBE AND SAID CORRECTION TUBE BEING COEXTENSIVE EACH OF SAID TUBES HAVING AN UPPER END AND A LOWER END, SAID MEASURING TUBE AND SAID CORRECTION TUBE EACH OPERATIVELY CONNECTED TOGETHER AND TO A VOLUME OF A REFERENCE LIQUID MEDIUM AT THE LOWER ENDS THEREOF WHEREBY SAID REFERENCE LIQUID MEDIUM MAY PROVIDE AN INDICATING LEVEL IN SAID TUBES VARYING IN RESPONSE TO FLUID PRESSURE APPLIED TO THE UPPER ENDS OF SAID MANOMETER TUBES AND SAID REFERENCE LIQUID MEDIUM, MEANS FOR SELECTIVELY VARYING THE FLUID PRESSURES APPLIED TO SAID REFERENCE LIQUID MEDIUM AND THE UPPER END OF SAID MEASURING TUBE, MEANS FOR CORRETING THE LEVELS OF THE LIQUID MEDIUM IN THE MEASURING AND CORRECTION TUBES OF SAID MANOMETER, AND MEANS OPERATIVELY ADJUSTABLE TO VARY THE FLUID PRESSURE APPLIED TO THE UPPER END OF SAID MEASURING TUBE AND SIMULTANEOUSLY VARY THE FLUID PRESSURE APPLIED TO THE UPPER END OF SAID CORRECTION TUBE INVERSELY WITH RESPECT THERETO FOR COMPENSATING SAID MANOMETER TUBES FOR VARIATIONS IN THE VOLUME OF SAID REFERENCE LIQUID MEDIUM.