110 Prof. Faraday on some Points of Magnetic Philosophy. 



the magneto-electric current : — it is never reversed without re- 

 version of the polarity, and reversion of the polarity always re- 

 verses the induced current. 



3357. The hard steel sphere was now made a magnet, and 

 though not of good shape to retain magnetism, being very short, 

 yet it was able to sustain being placed in the magnetic field, in a 

 position the reverse of the polarity of that field, and yet retain 

 its polarity; for when taken out and examined by a magnetic 

 needle, the polarity was found to be the same as before. Such 

 being the case, it seemed to me that this magnet might be em- 

 ployed to represent, according to the view of those who conceive 

 that iron and bismuth are polarized in opposite directions in the 

 magnetic field, both iron and bismuth ; inasmuch as it could be 

 placed in the field in that condition of polarity, which these are 

 then supposed respectively to acquire. The globe magnet was 

 therefore placed in the magnetic field in a position conformable 

 to that of the dominant magnet, i. e. with its N pole towards 

 the S pole of the magnet, &c. ; and being rotated, it gave an 

 induced magneto-electric current like that of the standard and 

 of iron (3352. 3353.). The dominant magnet was then with- 

 drawn to a distance (3353.) and the globe rotated by itself; it 

 gave, as it ought to do, the same current as before ; for it, by 

 its coercitive force, retains permanently that state of polarity, 

 which the iron could receive only temporarily whilst in the mag- 

 netic field. Being now turned 180° in a horizontal direction, 

 the globe magnet was reversed as regards the dominant magnet 

 (the latter being, however, still at a distance), and now the globe 

 magnet gave a current the reverse of the former, or of the 

 standard current ; and yet a very consistent current in relation 

 to its own polarity. 



3358. The dominant magnet was now gradually brought up, 

 and its effect on the reversed globe magnet observed. The cur- 

 rent from the latter became less and less, and at last was in- 

 verted, becoming like that of the standard current ; nor can that 

 be wondered at, when it is considered that the dominant magnet 

 was the largest supplied by Logeman to the Great Exhibition, 

 and able to sustain a weight of 430 pounds, and the sphere 

 magnet only - 8 of an inch in diameter, and very imperfectly 

 hardened in the interior. But when the dominant magnet was 

 withdrawn a little, a place was soon found for the globe magnet, 

 where its rotation in either direction produced no current at all. 

 Outside of this place, the rotated sphere gave a current, the re- 

 verse of that of the standard ; whilst the iron and bismuth 

 spheres in the same place, gave currents alike in kind and the 

 same as that of the standard. In this region, therefore (and it 

 is like the whole of the magnetic field of many inferior yet very 



