^4 Prof. Faraday on some Points of Magnetic Philosophy. 



ought to be more favourable to the determination of magnetic 

 force upon it before the induction than after ; whereas if, accord- 

 ing to my view, the polarity is not reversed, but is the same as 

 that of the magnet, the metal ought to be more favourable to 

 the determination of magnetic force upon or through it after 

 induction than before. Believing this to be an experiment which 

 would settle the question of reverse polarity, and perhaps the 

 existence or non-existence of physical lines of magnetic force, I 

 have made many attempts in various ways, and especially by 

 alternating motions of cylinders and balls of bismuth between 

 soft iron magnetic poles furnished with helices, to obtain some 

 results due to the time of induction, but have been as yet unable 

 to succeed. I cannot doubt that time is concerned; but it 

 seems to be so brief in period as to be inappreciable by the means 

 I have employed. 



33.20. Professor Thomson has put this matter of time and 

 polarity in another form. If a globe of bismuth be placed with- 

 out friction in the middle of the magnetic field, it will not point 

 or move because of its shape ; but if it have reverse polarity, it 

 will be in a state of unstable equilibrium; and if time be an ele- 

 ment, then the ball, being once moved on its axis ever so little, 

 would then have its polarity inclined to the magnetic axis, and 

 would go on revolving for ever, producing a perpetual motion. 

 I do not see how this consequence can be avoided, and therefore 

 cannot admit the principles on which it rests. The idea of a 

 perpetual motion produced by static forces is philosophically illo- 

 gical and impossible, and so I think is the polarly opposed or 

 adverse static condition to which I have already referred. 



3321. It is not necessary here that I should refer to the 

 manner in which my view of the lines of magnetic force meet 

 these cases, for it has been done in former papers (2797, &c.) ; 

 but I will call the attention of those who like to pursue the sub- 

 ject, to a true case of reverse polarity in the magnetic field (Ex- 

 perimental Researches, 3238, fig. 15), and there they will easily 

 see and comprehend the beginning of the rotation of Professor 

 Thomson's bismuth globe, and its continuance, if, as supposed, 

 the polar state represented in the figure could be continually 

 renewed. 



3322. When the north pole of a magnet repels a piece of 

 bismuth in a vacuum, or makes a bar of it set equatorially, and 

 is found to produce like actions with many paramagnetic bodies 

 when surrounded by media a little more paramagnetic than 

 themselves, and with as many diamagnetic bodies when sur- 

 rounded by media a little less diamagnetic, it would seem more 

 cautious in the first instance to inquire how these latter motions 

 take place, and how it is that parts, which with the paramag- 





