ELECTRO-MAGNETISM. 



makes its exit ; and this quite independ- 

 ently of the position of the needle with 

 respect to the magnetic poles of the 

 earth. Wilke, on the contrary, ima- 

 gined that he could establish the exist- 

 ence of an invariable connexion between 

 the negative electricity and the northern 

 polarity. The laborious series of expe- 

 riments which were undertaken by Van 

 Swinden, with the express view of re- 

 conciling these strange discrepancies, 

 instead of settling the dispute, seemed 

 only to leave it more than ever embar- 

 rassed with difficulties. About the year 

 1777, the celebrated Beccaria engaged 

 in a similar investigation ; and although 

 he, like his predecessors, failed in disco- 

 vering the true nature of the magnetic 

 influence of electricity, yet he noticed a 

 singular fact which occurred to him in 

 the course of his experiments, but of 

 which he does not appear to have ap- 

 preciated the value. He found that a 

 needle, through which he had sent an 

 electric shock, had, in consequence, ac- 

 quired a curious species of polarity; for, 

 instead of turning as usual to the north 

 and south, it assumed a position at 

 right angles to this, its two ends point- 

 ing to the east and west. There is little 

 doubt, that if he had followed up the 

 inquiry which this important fact had 

 opened to him, he would soon have ar- 

 rived at the great discovery which was 

 made about half a century afterwards 

 by Oersted, and which has dispelled the 

 whole mystery. 



(7.) As nothing had been gained by 

 following the more violent operations of 

 highly condensed charges of electricity, 

 other philosophers occupied themselves 

 in the attentive study of the more tran- 

 quil influence of this agent, when merely 

 accumulated in insulated conductors, 

 and exerting simply its attractive and 

 repulsive powers in conjunction with 

 those of magnetism. But however these 

 actions mightbecombined,nothing could 

 be detected that indicated any interfe- 

 rence of agency or modification of effect 

 consequent on the combination. An 

 electrified body is found to exert the 

 same attractions and repulsions on a 

 magnetized needle as it does on the same 

 needle when devoid of magnetism ; nor 

 does it, like magnetism, exhibit any de- 

 cided preference for iron, compared with 

 its action on other metals. When the 

 two agencies are united in the same 

 body, as when bars of steel, already 

 rendered magnetic, are also charged 

 with electricity, and placed so as to act 



upon one another, their electrical and 

 their magnetic actions appear to be per 

 fectly distinct, and in no respect to in- 

 fluence or modify one another. 



(8.) The discovery of galvanism, and 

 the invention of the Voltaic apparatus, 

 opened a new field of inquiry ; for, by 

 furnishing the experimentalist with the 

 means of maintaining a continuous cur- 

 rent of electricity in very large quantity, 

 it enabled him to study the effects of this 

 powerful agent under circumstances of 

 a very different kind from those he had 

 previously had under his command. The 

 electro- chemical phenomena, brought 

 to light by its application to another 

 branch of physical science, for a long 

 time occupied the talents and absorbed 

 the attention of scientific men in every 

 part of Europe ; and many years elapsed 

 before Voltaic electricity was applied 

 with any success to determine the in- 

 fluence which it so directly exerts over 

 magnetized bodies. The few inquirers 

 who sought to establish a relation or 

 identity between these two powers, ex- 

 cited but little attention, in consequence 

 either of the obscurity of their reason- 

 ings or the inaccuracy of their experi- 

 ments. The various hints interspersed 

 among the journals of this period, re- 

 specting movements having been ob- 

 served in the magnetic needle by the 

 action of the Voltaic pile, were too vague 

 and uncertain to warrant any determi- 

 nate conclusion. The most definite and 

 authentic narrative relating to this sub- 

 ject was that of Ritter, who asserted 

 that a needle, composed of silver and 

 zinc, had arranged itself in the magnetic 

 meridian, and had been slightly attracted 

 and repelled by the poles of t a magnet. 

 He also stated,that by placing a gold coin 

 in the Voltaic circuit, he had succeeded 

 in giving to it positive and negative elec- 

 tric poles ; and that the polarity so 

 communicated was retained by the gold 

 after it had been in contact with other 

 metals, and appeared, therefore, to par- 

 take of the nature of magnetism. A 

 gold needle, placed in similar circum- 

 stances, acquired still more decided mag- 

 netic properties. These experiments 

 suggested to Ritter some vague idea 

 that electrical combinations, when not 

 exhibiting their electric tension, were in 

 a magnetic state ; and that there existed 

 a kind of electro-magnetic meridian de- 

 pending on the electricity of the earth, 

 at right angles to the magnetic poles. 

 But these speculations were of too crude 

 a nature to throw any distinct light on 

 B 2 



