The following is a paper by H. Aspden published in The Journal of Scientific Instruments, vol. 29, pp. 2-7, (1952).
A TWO FLUXMETER METHOD OF MEASURING FERROMAGNETIC HYSTERESIS LOSS
Abstract: Ferromagnetic hysteresis loss is usually measured by the method of reversals or the step-by-step method, both of which involve the use of a ballistic galvanometer or a fluxmeter. The necessity for recording observations and measuring the area of the hysteresis loop can be eliminated by using a second fluxmeter to integrate successive electrical discharges, which are initiated by a chosen change in flux density and are proportional in magnitude to the magnetizing field. The total deflexion of this second fluxmter over one complete cycle of magnetization is a direct measure of the hysteresis loss. By this means it is possible, without sacrificing accuracy, to reduce the time of measurement to a small fraction of that usually required by conventional methods.
Commentary: This paper was written during a period when the author was working for a Ph.D. degree which involved experimental research on the eddy-current anomaly. See the related paper: [1956a]. However, this method was not used in the eventual experiments which were the basis of that Ph.D.