80 NOMOS, 



and first of all, with reference to the phenomena of 

 magnetism. 



Influenced by many weighty arguments, of which 

 some have been stated, M. Ampere arrived at the 

 conclusion that magnetical phenomena are due to the 

 circulation of electrical currents around the magnet ; 

 and by thus discarding the idea of any special mag- 

 netical agent, he greatly simplified the theory of 

 magnetism. As left by him, however, the theory is 

 still complex, and perhaps incomprehensible ; for it 

 assumes the continual presence in every conductor 

 of a double series of currents, arranged cross-wise 

 with respect to each other. But this is certainly 

 not the final simplification of which the subject is 

 capable. 



In the experiment of the moveable spiral con- 

 ductor, it was shown that the powers of the mag- 

 netic poles could be explained by the common 

 reaction of electrical currents. The spiral conductor 

 (which was in every respect a true magnet for the 

 time being) gave evidence of one current passing 

 along the wire which formed the coil; but of one 

 only. Where, then, is the evidence in favour of 

 the double series of currents ? Now, the facts which 

 remain to be considered, and which furnish the 

 answer to this question, are the meridional move- 

 ment of the magnetic needle, and the cross move- 

 ment of the same needle when placed in relation to 

 an electrical conductor; and these facts we now 

 propose to examine. 



