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 166
meticallyFig. 99. in a glass tube. When this is appliedto a U-magnet, the iron is attracted withsufficient force to hold the tube in con-tact with the poles. The polarity in-duced in the iron is precisely as greatas when only air is interposed. Theresult is the same when the iron is en-closed in a…
