Moisture sensor

To measure moisture or humidity, a probe in the form of electrical capacitor means, the capacitance of which varies depending on surrounding moisture content, is connected (via 11a, 11b) to an oscillator circuit (not shown), the frequency of oscillation of which is a function of said capacitance. A counter is connected to the circuit and is operative to count its oscillations in a given time and display these as a measure of the moisture content adjacent said probe. The probe is of particularly simple form, consisting of a cut open loop or a pair (10a, 10b) of conductive wires which are coated or covered in substantially waterproof, electrically insulating material and folded or twisted into two or more helices.