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 144
MAGNETISM, 313 … Fig 219. {a.) If it be free to move in a horizontal plane, it is a horizontalneedle; e. g., the mariners or the survey-ors compass (Fig. 219). It will come torest pointing nearly north and south.If the magnet be free to move in a ver-tical plane, it constitutes a vertical ordipping needle (Fig.…
Electricity · Magnetism
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