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XXI.—Transverse Induction Changes in Demagnetised and Partially Demagnetised Iron in relation to the Molecular Theory of Magnetism

Published online by Cambridge University Press:  15 September 2014

James Russell
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Extract

In a former communication the æolotropy of iron, demagnetised by the method of decreasing reversals, was shown. During the early stages of induction the permeability is greater to the re-application of a magnetising force in the same direction—whether positive or negative—as that used in the immediately preceding demagnetising process, than to a transverse force. The demagnetisation is complete in the sense that there is no external polarity, and also in the sense that perfect symmetry exists to the subsequent application of the same positive or negative directional field. This symmetry being uni-directional, æolotropy immediately appears if the subsequent magnetising force contains a transverse component.

Type
Proceedings
Information
Proceedings of the Royal Society of Edinburgh , Volume 32 , 1913 , pp. 291 - 314
Copyright
Copyright © Royal Society of Edinburgh 1913

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References

page no 292 note * “Magnetic Shielding in Hollow Iron Cylinders,” Trans. Roy. Soc. Edin., vol. xl. pp. 649–654 (on “Magnetic Æolotropy“).

page no 292 note † “The Molecular Condition of Iron demagnetised by Various Methods,” Proc. Roy. Soc. Edin., vol. xxiv. p. 544.

page no 294 note † A circular disc of cardboard, on which was drawn the stereographic projection of a hemisphere, could rotate from beneath on the surface of a wooden board. Over this arrangement a piece of transparent paper was securely stretched. Obviously the new co-ordinates of any series of known points marked on the paper could, on the rotation of the disc through any required angle, be immediately read off. Mr Blaikie's apparatus has been exhibited at the Royal Society of Edinburgh and other societies, but no account of his ingenious device appears to have been published. Dr Dyson, Astronomer Royal, kindly showed me Mr Blaikie's device at the Royal Observatory, Edinburgh, which suggested the above modification of the more complete apparatus.

page no 308 note * “The Shift of the Neutral Points, etc.,” Proc. Roy. Soc. Edin., vol. xxix. pp. 30–34.