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 285
n barto rotate rapidly, by drawing the hand over the axis,the needle is powerfully deflected. As the iron ap-proaches the poles of the steel magnet, it becomesmagnetic; as it recedes from them, its magnetismdisappears. While one end of the bar is leaving thenorth pole, or approaching the south… … tion. During the other half of the revolution, thesame end of the bar is approaching the north poleor receding from the south, and a reverse current isproduced. The two currents are conveyed to thegalvanometer in one direction by means of the pole-changer on the axis of the revolving bar. The…
