Apparatus for determining soil moisture content

Claim 1

A MOISTURE INDICATOR COMPRISING A FIRST TUBE DEFINING AN INTERNAL CHAMBER, A LIQUID-PERMEABLE SECTION ON THE FIRST TUBE FOR COMMUNICATION OF LIQUID BETWEEN THE EXTERIOR OF THE FIRST TUBE AND THE INTERNAL CHAMBER THEREIN, A SCALE TUBE DISPOSED PARTIALLY WITHIN THE INTERNAL CHAMBER OF THE FIRST TUBE AND PARTIALLY EXTERIORLY OF THE FIRST TUBE, MEANS FOR MOVABLY MOUNTING THE SCALE TUBE ON THE FIRST TUBE FOR MOVEMENT OF THE SCALE TUBE INTO AND OUT OF THE INTERNAL CHAMBER IN THE FIRST TUBE AND FOR PROVIDING A SEAL AGAINST ATMOSPHERE BETWEEN THE INTERNAL CHAMBER IN THE FIRST TUBE AND THE SCALE TUBE, SAID SCALE TUBE DEFINING ON INTERNAL CHAMBER EXTENDING THROUGH THE SCALE TUBE WHICH IS CLOSED TO ATMOSPHERE AT THE END OF THE SCALE TUBE DISPOSED EXTERIORLY OF THE FIRST TUBE AND WHICH COMMUNICATES WITH THE INTERNAL CHAMBER IN THE FIRST TUBE THROUGH THE PORTION OF THE SCALE TUBE DISPOSED WITHIN THE INTERNAL CHAMBER IN THE FIRST TUBE, A FIRST VENT IN THE FIRST TUBE COMMUNICATING BETWEEN THE INTERNAL CHAMBER THEREIN AND THE EXTERIOR THEREOF, A SECOND VENT IN THE PORTION OF THE SCALE TUBE DISPOSED EXTERIORLY OF THE FIRST TUBE AND COMMUNICATING BETWEEN THE INTERNAL CHAMBER IN THE SCALE TUBE AND THE EXTERIOR THEREOF, VALVE MEANS FOR SELECTIVELY SEALING AND OPENING EACH OF THE FIRST AND SECOND VENTS, AND INDICIA ON THE PORTION OF THE SCALE TUBE DISPOSED EXTERIORLY OF THE FIRST TUBE FOR DEFINING A PREDETERMINED INITIAL VOLUME OF AIR IN THE INTERNAL CHAMBER IN THE SCALE TUBE BETWEEN THE LEVEL OF AN INDICATING LIQUID IN THE INTERNAL CHAMBERS OF THE FIRST TUBE AND THE SCALE TUBE AND THE CLOSED END OF THE INTERNAL CHAMBER IN THE SCALE TUBE AND INDICATING THE MAGNITUDE OF SUCH VOLUME OF AIR IN THE INTERNAL CHAMBER OF THE SCALE TUBE RELATIVE TO THE INITIAL VOLUME OF AIR THEREIN RESPONSIVE TO CHANGES IN THE LEVEL OF AN INDICATING LIQUID THEREIN.