[ 164 J [March I, 



REPORT OF CHEMISTRY AND EXPERIMENTAL PHILOSOPHY. 



'E rssume our i!liis(ralioiis of the nev 

 nnd iniporlaiit experiments which 

 connect Voilaic Kleelricily, nnd Magneti-in, 

 niiJ which prove that the latter, il)e very 

 citiidel ofVtiie auraciive and irravitatins;- 

 theory, is but a uieciianical eflect of certain 

 mundane circnlalions. This Slagaziue will 

 thus co'itain fullerdetuils on thissuhjeet than 

 liny oiher jounial. 



M. G2RSTED, Professor of the University 

 of Copenhairen, opened this new field to the 

 infjiiiries of philosopjjers. It is to him that 

 we owe the line observation, that a nietnllic 

 ■wire, which commimioales with the two ex- 

 tremities of a voltaic electrical apparatn-, 

 acquires the very remarkable properly of 

 acting at a distance on a ma;;'netic needle. 

 This metallic wire has been named the eon- 

 juuclive wire. 



The conjunctive wire, in tlie experiment 

 of M. Oilrsted, will become healed, but if it 

 is of sulficient dianinter it will not burn ; and 

 its action may be observed on a mat^etic 

 needleatsome di-tauce. For twenty-three 

 years the eleciiic piles of Volta had been in 

 use, and no pliilosopher had yet Ihouarlil of 

 bringing a ma;^netic needle near one of tliese 

 piles in action. 



Supposiug the metnlUc plates which form 

 (he electrical apparatus with troughs, to be- 

 gin with zinc avA finish with co|)pcr, the 

 electrical current, supposed to be in the con- 

 jwnctire wire, would n;o from the first p'ate 

 to the la^t. Now, imagine anoi<;er conjunc- 

 tive wire of the same apparatus, placed pa- 

 ■ rallel to the first, and disposed in such a 

 manner that it may transmit anelectrical 

 ciirrenl in n direction contrary to the first, 

 the two wires will repel. 



M. Arago niag;netis(Hl a slip of iron, nnd 

 afterwards a steel wire, by puttins; them in 

 contact wiih, or under the inlluence of, the 

 conjunctive wire. A simple method of maa^- 

 netisiug a steel needle by the co.njunclivo 

 wire, consists in placing the needle in the 

 part of the conjunctive wire which is twisted 

 spirally : whether the needle is placed di- 

 rectly upon the threads of the spiral, or en- 

 veloped in paper or a glass tube to prevent 

 contact with the conjunctive wire, it be- 

 comes magnetised, and its north nnd south 

 poles, corresponding to the nonh and 

 south poles of the terrestrial magnet, will 

 be deteniiined by the direction of the 

 spiral which bears tlie needle. If the 

 conjunctive wire be placed in a vertical 

 plane, and in the directioi. of the electric 

 current which passes from the zinc plate of 

 the apparatus to the copper plate, the g;ene- 

 ratina; point of the spiral may turn from 

 left to right of the current, or from right to 

 left; in the first case, the south pole of the 

 needle, corresponding to the north pole of 

 the terrestrial majnet, will be on the side 

 of the zinc plate of the apparatus ; in the 

 second case, it i» the north pole of the 

 Btedlewbick i$ oa that side. 



M. Arago, following the theory of M. 

 Ampere, conceived the idea of twisting a 

 conjunctive wire in the manner of two sym- 

 metrical spirals placed one after the other ; 

 these spirals diflVred from each other only 

 as to the direction in which their generating 

 points turned round their hollow spindles : 

 by putting a needle in each spindle, the two 

 tieeilles became m.ignetised at the same 

 time, so that tlieir poles of the same name 

 were contiguous. In transmitting a dis- 

 charge of a Leyden phial through a copper 

 wire twisted in the same manner, in the man- 

 ner of two consecutive symmetricnl spirals, 

 M. Arago has further observed, that the steel 

 needles placed on these spirals became mag- 

 netised by the electric fluids of ordinary nui- 

 cl.in'_'s, as well as by the voltaic apparatus. 



M. Ampere has presented three new ar- 

 rangements of apparatus, of his invention. 

 The ,f:r\t shews a circular conjunctive wire 

 submitted to the action of a voltaic appara- 

 tus, and which is directed by the action of 

 the terrestrial globe in a vertical plane, per- 

 pendicular to the plane of the magnetic me- 

 ridian. Thti .second apparatus consists in a 

 circuit almost closed, and of a rectangular 

 form, which turns round a horizontal axis 

 perpendicular to the plane of the magnetic 

 meridian, and the plane of which inclines to 

 take, by the action of the earth, a directiou 

 perpendicular to that of the inclination of 

 the needle.* It is variable, like the declina- 

 tion, according to times and places. The 

 third apparatus of M. Ampere exhibits a 

 conjunctive v.ire twisted spirally, the ex- 

 tremities of which are attracted and repelled 

 by a magnetic bar, as those of a needle 

 would be. 



M. Ampere, in commtmications which he 

 made to theAcaden)y of Sciences, Sept. ISth 

 1820. — I showed that the current which is in 

 the pile, acts on the magnetic needle like 

 thatof the conjunctive wire, and described the 

 experiments by which I had established the 

 atiraciiou or repulsion of the whole of a 

 magnetic needle, by the conjunctive wire. 

 He described the instruments which he pro- 

 posed to construct, and, among others, galva- 

 nic spirals; and announced that the latter 

 would pro Juce, in all cases, the same efiecis 

 as magnets. Afterwards he entered into 

 some details on the manner in which the mag- 

 nets act ; a-i only owing their properties to 

 electric currents in planes pcrpaidictilar to 

 their a.ris,f and upon similar currents 

 in the terrestrial globe; in short, be reduced 

 alltho magnetic pheuomenato effects purely 

 electric. 



• This inclination was at Paris on the 22d 

 April, 1819, eso25'. 



+ How perfectly conformable to (he The- 

 ory of Matter and Motion, and to the expla- 

 nations of this and other phenomena on me- 

 chanical principles, printed iu this Miscellanv. 



On 



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