42 hlectro- Magnetic Experiments. 



most lidenly has any action on the moirvet. Now, the electriciWr: 

 in the conjunctive wire of an electrical apparatus in action, is in- 

 deed latent, since it does not manifest itself to anv electrometer ; 

 and, in fact, M. Oersted performed last winter (ISIJ)) the expe- 

 riment which justified what he had conceived seven years before- 

 The result of this experiment has been known in Paris onlv three 

 months, and already several distinguished philosophers have de^ 

 dueed from it most important consequences, both for magnetism 

 and electricity. We shall give an account of these as succinctly 

 as possible. 



Supposing the metallic plates which form the electrical appa- 

 ratus with troughs, to begin with zinc and finish with copper, the 

 electrical curre5«t, supposed to be in the conjunctive wire, would 

 go from the first plate to the last. Now, imagine another con- 

 junctive wire of the same apparatius, placed parallel to the first, 

 and disposed in such a maimer that it may transmit an electrical 

 current in a direction contrary to the first, tiie two wires will re^ 

 pel. If the currents are in the same direction, they will attract. 

 M. Ampere was the first to observe these attractions and repnl- 

 £5ions at a distance, between bodies traversed by an electric fluid 

 which docs not manifest any tension. 



M. Arago magnetised a slip of iron, and afterwards a steel 

 wire, by putting them in contact with, or under the influence of, 

 the conjunctive v>irc. A simple method of magnetising a steel 

 needle by the eonjunctive wire, consists in placing the needle in 

 the part of the conjunctive wire which is twisted spirally : whe- 

 ther the needle is placed directly upon the threads of the spiral, 

 or enveloped in paper or a glass tube to prevent contact with 

 the conjunctive wire, it becomes magnetised, and its north and 

 south poles, corresponding to the north and south poles of the 

 terrestrial magnet, will bedetermined by the direction of the spiral 

 which bears the needle. If the conjunctive wire be placed in a 

 Vertical plane, and in the direction of the electric current which 

 passes from the zinc plate of the apparatus to the copper plate, 

 the generating point of the spiral may turn from left to right of 



ma;4ntt, vvitliout any o'Jier cliangc resulting in the nature of the action, ex- 

 cept the phffiiiomeiia known to rcMilt from tlie mutual action of two mag- 

 nets; and 4th, that the distribution of the electric fluid in the conjunctive 

 ■wire, is the same as in planes peipcmlicular to the line which joins the two 

 poles Ota ma;'nel, following limited curves, traced in these planes around 

 the axis of the magnet. 



M. Ampere thus establisiied tlie identity of electric and magnetic fluids, 

 ^Iiilc M. Arago made his fine experiment on the magnetising ol slips of iron 

 bv tlhe right conjunctive wire. Since these fcn'o philosophers have further 

 .idded tli(f magnetising of a steel bar by a conjunctive wire twisted spirally- 

 round (his bar ; and that they have anticipated the principal circumstances 

 of that magnetising, it would appear, lliiit they cannot dispense with adrait- 

 ting the identity of the two Quids. 



the 



