Modern electricity and magnetism, theoretically and practically considered (1885)
Avery, Elroy M[cKendree], 1844- [from old catalog] · New York and Chicago, Sheldon and company · leaf 124
gnetic meridian bythe directive influence of the earth; in the galvanometer,this is obviated almost wholly by the use of an astatic needle(§ 439). In Oersteds apparatus, the current makes but asingle course about the needle ; in the galvanometer, thewire is insulated and coiled many times about the… … Fig. 201. priate slit in the coil. If both needles were within thecoil, since their poles are reversed, the same current wouldtend to deflect them in opposite directions and thus theaction of one needle would neutralizethat of the other. The astatic needleis suspended by an untwisted silkfibre from…
Electricity · Magnetism
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