Abstract: A parameter representative of a physical property of a continuously moving metal strip is determined by repetitively generating acoustical shock waves, containing ultrasonic frequencies, and adjacent the strip and measuring the speed of transmission of the shock wave in the strip. An electric spark generator with a collimator feeds the acoustic energy to the strip 10 and four microphones arranged as a first pair on opposite sides of the strip spaced a known distance from a second pair also on opposite sides of the strip pick up the signal transmitted through the strip. The difference between the mean time of arrival at the first pair and the mean time of arrival at the second pair enables the velocity of propagation in the strip to be determined despite movements of the strip transverse to its plane. The velocity of propagation in particular may be used as a measure of Young's modulus and hence, in the case of a material such as aluminium, as a measure of the temperature of heat treatment.

Abstract: A fail-safe long interval timer has a capacitor which is charged progressively and the voltage across which is sampled momentarily at intervals, without fully discharging the capacitor, by connecting a pulse transformer across the capacitor for the duration of very short pulses which act on a solid state switching element. When the sampled pulses reach a threshold amplitude level a threshold device is triggered, after a time interval which will be determined by the charging circuit and the capacitor as well as the characteristics of the sampling circuit.

Abstract: In order to detect derailment of a railway vehicle each vehicle in a train is provided with an acceleration responsive device which, in response to the vehicle acceleration resulting from derailment of the vehicle transmits a short range radio signal to a receiver installed in the engine to provide a visual or audio alarm. In one practical arrangement requiring no routine maintenance each transmitter unit has a resonant circuit which is energized as a result of the stressing of a piezo-electric crystal upon vehicle derailment, avoiding the need for any separate electrical power source on the vehicle.

Abstract: A method of detecting ground faults in ungrounded equipment having an electrical supply. The method comprises the steps of:Connecting either side of the supply to a chassis ground terminal of the equipment;Impressing a voltage varying alternately between two predetermined values on the terminal relative to one side of the supply;Detecting and monitoring, with respect to this side of the supply, the resulting potential between this side the chassis ground, said potential varying between predetermined magnitudes in the absence of any ground leak;Monitoring said potential, ground faults in the equipment being detectable by a change in magnitude of said varying potential, establishing ground faults by changes in the magnitude of the varying potential andLocating the faults with respect to the sides of the supply from variations to the upper and lower predetermined values.Preferably the limits to the voltage will be a predetermined value and substantially zero.

Abstract: A detective circuit for railway points composed of three track sections connected together at a junction or for a railway crossing composed of four track sections connected together at a junction.