Apparatus for measuring moisture of soil

Claim 1

THE COMBINATION WITH A MOISTURE-SENSITIVE ELEMENT COMPRISING A BLOCK OF POROUS ABSORBENT MATERIAL HAVING COMPLETELY EMBEDDED THEREIN A PAIR OF SPACED ELECTRODES COATED WITH BLACK PLATINUM, WHEREBY THE EFFECTIVE SURFACE AREA OF THE ELECTRODES IS INCREASED MANY TIMES AS COMPARED TO THE SURFACE AREA OBTAINED FROM A MERE INCREASE IN THE PERIPHERAL DIMENSIONS OF THE ELECTRODES, OF A MEASURING INSTRUMENT COMPRISING A WHEATHSTONE BRIDGE COMPLETELY DEVOID OF CONCENTRATED CAPACITANCE, THERE BEING AN INDICATOR ACROSS ONE DIAGONAL OF SAID BRIDGE AND A CONNECTION ACROSS THE OTHER DIAGONAL OF SAID BRIDGE FOR SUPPLYING HOUSE POWER SUPPLY THERETO, SAID BRIDGE HAVING FOUR ARMS IN ONE OF WHICH IS A SERIES OF SELECTABLE RESISTORS, IN TWO OTHER SAID LAST TWO ARMS, AND BEING A POTENTIOMETER BETWEEN SAID LAST TWO ARMS, AND IN THE FOURTH ARM SAID BLOCK OF POROUS ABSORBENT MATERIAL CONNECTED THERETO BY RUBBER-COVERED LEADS.