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A simple form of 60-cps hysteresis loop tracer for materials of high and low permeability is described. By including a differential form of balance control, all 60-cps voltage present in the leads and pickup coils, prior to the insertion of a magnetic specimen into the field coils, may be completely balanced out. The sensitivity is sufficient to provide a one-inch peak to peak deflection on a Dumont 304A cathode-ray oscilloscope for a flux change of 0.1 maxwell.
D. H. Howling (Thu,) studied this question.