Abstract: A linear irrigation system has the wheels on each end angled outward to stretch the entire pipe. Some of the vehicles in the middle of the pipe are steered responsive to the distance the elongated pipe is from a guide line. Steering is controlled by the movement of a cable. Bridges upon a tube on the cable are used to activate a microswitch. The microswitch itself is on a carriage which is responsive to the distance of the elongated pipe from a guide line. Therefore when any correction is needed, a predetermined correction is applied and no additional correction is applied until the carriage carrying the microswitch is again moved. The wheels are individually steered. The correction is almost instantaneous and is not dependent upon changing the angle of the entire moving pipe.

Abstract: A moisture detector comprises a shell adapted to float with an anode and cathode on the bottom portion thereof. The anode may be of sacrificial metal which is electrolyzed to increase the conductivity of moisture contacting the electrodes. Also, a water soluble electrolyte may be placed either on the electrodes or close thereto. A plug on the shell may provide for a pair of remote electrodes. A piezoelectric transducer system of improved design involves shaping of the chambers in said shell.

Abstract: A compressed dehydrated cellulose sponge wafer has conductive plates attached to opposing faces. A bridging conductor electrically connects the two plates together upon swelling of the wafer responsive to its contact with moisture. One edge of the sponge is treated with adhesive so as to form a hinge. The wafer opens like a book upon contact with moisture forcing the extending plates into contact.