In a paper laid before this Society in July 1902, the magnetic æolotropy of iron demagnetised by decreasing reversals of co-directional and transverse magnetising forces, and also of iron left transversely magnetised, was established. In later communications (July 1903 and July 1904) it has further been shown that iron and nickel demagnetised by decreasing reversals of a directional force, develop an induction component at right angles to the subsequent magnetising force, which tends to disappear as saturation values are reached, when the angle between these two forces is other than 0° and 90°. In annealed iron this property is absent.