Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . 25 356. The induction of magnetism by the earth is greatly facilitated by causing a movement among the particles of the bar, as by percussion or twisting. Let a bar of iron be held in the line of the dip, and rr iK-r its lower end brought Fig. 157. ° near the north pole of amagnetic needle. Thepole will be repelled,and will come to rest atsome distance from thebar, as shown in Now strike theupper end of the barwith a hammer, and theinduced ma
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . 25 356. The induction of magnetism by the earth is greatly facilitated by causing a movement among the particles of the bar, as by percussion or twisting. Let a bar of iron be held in the line of the dip, and rr iK-r its lower end brought Fig. 157. ° near the north pole of amagnetic needle. Thepole will be repelled,and will come to rest atsome distance from thebar, as shown in Now strike theupper end of the barwith a hammer, and theinduced magnetism willbe so much increasedthat the needle willswing round, and itssouth pole be drawn tothe bar, as indicated bythe dotted lines in thecut. The polarity thusinduced is not reversedby merely inverting therod, but the aid of per-cussion will be required, in order to remove or reversethe magnetism. This is especially the case when asteel bar. is employed instead of an iron one. 357. Take a piece of iron wire, and, placing it ina vertical position, twist it powerfully. It will nowbe found to sustain iron filings at its extremities, and. ?26 DAVISS to turn itself north and south, when balanced on apivotj as shown in Fig. 158. The end which was Fig, 158.
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
