Paper, 'Magnetic polarity and neutrality' by D E [David Edward] Hughes

Description

Hughes writes: 'In recent papers upon the theory of magnetism, I gave the opinion drawn from a long series of personal researches, that magnetism in iron and steel is entirely due to the inherent polarity of its molecules, the force of which could neither be destroyed nor augmented; that, when we have evident magnetism, the molecules rotate so as to have all their similar polarities in one direction; and that neutrality is a symmetrical arrangement or a balancing of polar forces, as in a closed circuit of mutual attractions. The series of researches which I now present bear unmistakable testimony to the truth of these views, showing the opposite polarities which exist in an apparently neutral bar of iron; and that it is by this means alone that external neutrality occurs in the iron cores of an electro-magnet upon the cessation of the inducing current. The instrument used for measurements consists of a delicate silk fibre-suspended magnetic needle, always brought to its zero-mark by the influence of a large magnet at a distance, the angle of which gives the degree of force required to balance any magnetised body placed on the opposite side of the needle. It can also employ electromagnetic effects by the use of two opposing coils on each side of the needle, balanced so that an electric current passing through the coils has no influence on the needle, except when a piece of iron or steel is placed inside one of the coils; this again being balanced and measured by the large revolving magnet.'

Annotations in pencil and ink.

Subject: Magnetism

Received 23 February 1884. Read 6 March 1884.

A version of this paper was published in volume 36 of the Proceedings of the Royal Society as 'Magnetic polarity and neutrality'.

Reference number

PP/4/33

Earliest possible date

1884

Physical description

Ink and graphite pencil on paper

Page extent

25 pages

Format

Manuscript