Abstract: A magnetic detector includes a magnetizer generating a magnetic field; a first magnetic sensor for detecting a leakage flux resulting from a magnetically defective portion of an object moving in and relative to the magnetic field; a low-pass filter for extracting a low-frequency signal component contained in the signal output by the magnetic sensor, the low-frequency signal component being indicative of a floating flux which crosses the magnetic sensor and is a result of the object moving through the magnetic field; an amplifier for amplifying the extracted low-frequency signal component; a compensating coil excited by the amplified low-frequency signal component output by the amplifier, for generating a magnetic flux which cancels out the floating flux crossing the magnetic sensor; a high-pass filter for extracting a signal resulting from the magnetically defective portion and contained in the signal that is output by the first magnetic sensor; an output amplifier for amplifying a signal output by the high-p

Abstract: A radiation thermometer for measurement of the temperature of molten iron includes a probe tube with a sealed bottom in the form of a spheroidal shape and is made of zirconium boride ceramics. The probe tube is immersed in molten iron and radiation emitted from the spheroidal closed end of the probe tube is received by a sensor at the far end of the tube which is above the level of the molten iron. The spheroidal end of the probe tube is below the surface of molten iron by more than 10 times the inner radius of the probe tube.