Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . l magnet on its axis is properly classed with that of a „. ,^^ conductor around a magnet. When theconductor and mag-net are fastened to-gether, the latter iscarried round by themovement of theformer, as stated in<5. 171. Instead offastening a conduct-ing wire to themagnet, the currentmay be transmittedthrough the magnetitself, with the sameresult. 352. Electro-Magnetism as a Motive Power.—-The great velocity of motion, and the strongattractive forc
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . l magnet on its axis is properly classed with that of a „. ,^^ conductor around a magnet. When theconductor and mag-net are fastened to-gether, the latter iscarried round by themovement of theformer, as stated in<5. 171. Instead offastening a conduct-ing wire to themagnet, the currentmay be transmittedthrough the magnetitself, with the sameresult. 352. Electro-Magnetism as a Motive Power.—-The great velocity of motion, and the strongattractive force exhibited by many of the small elec-tro-magnetic instruments, naturally suggested theapplication of this power to the purposes of the artsas a mechanical agent; and numerous experimentshave been made with this view, but hitherto withoutsuccess. Professor Henry was the contriver of thefirst instrument whose motion depended upon mag-netic attraction and repulsion. In his little machine,an electro-magnet, whose polarity was alternatelyreversed, was made to vibrate above the north polesof two straight steel magnets. He, however, made19*. lll!i!l!!i!iOi!l!!lii!lllli|illi!lliilllllHlllll!l!llllll!ll!l:lll!l!lllllililll» 222 DAVISS MANUAL. no attempt to apply this power to practical purposesThere are obstacles of a purely mechanical characterin the way of its employment; these, though im-portant, are not perhaps insurmountable. But themost serious difficulties are those which arise fromthe nature of the power. The motion of the at-tracting poles of two electro-magnets towards eachother, actually lessens the attractive force in pro-portion to the velocity with which they approach;the same thing occurs in the recession of mutuallyrepelling poles. These phenomena are due to theinfluence of secondary electric currents produced bythe motion, which flow against the battery current,and of course partially neutralize its magnetizingpower. The secondary currents present a very for-midab
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
