The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 36
facing towards any oneof the needles, the north poleof the needle would alwaysbe deflected towards the lefthand of the swimmer. When the wire is bent intoa circle, a large number ofthese lines of force come to-gether in the interior, asshown in Fig. 7, and themagnetic action there is con-sequently… … Fig. 6
Telephone
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