Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity (1854)
Davis, Daniel · Boston : Palmer and Hall · leaf 234
immuiflMjijiHimiBflirafflBnjiifflMifflnRmiffliD magnetic MAGNET REVOLVING IN A COIL. 217 SO supported as to revolve by the earths action ina horizontal plane, instead of a vertical one. In this Fig. 150. ifliBi … flrafliflmBWHHWTRmiwiiimHiHmniiiMuy] case, the instrument must beplaced in such a position thatthe polarity shall be reversedwhen the revolving mag-net assumes the direction ofthe compass-needle, pointingnorth and south, 346. When a steel mag-net is placed in a proper po-sition near the revolving…
