The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

110 IAGNETISM.
If the north pole of a bar magnet, figure 11, be placed on
the centre of a circular plate of iron, a south polarity is given
Fig. 9. Fig. 10. Fig. 11.
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Fig. 12. Fig.13.
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to tlhe metal or plate touching the bar, and the under part becomes north, and from it will be suspended iron filings when
they are brought in contact with the plate. If the plate is cut
in the form of a star, as represented by figure 12, each point
becomes a stronger north pole. The part of the plate in con