Prof. Faraday on some Points of Magnetic Philosophy. 107 



or like the bottom of a chamber formed in the end of a magnetic 

 pole, a neutral place, or place of no magnetic action. 



3349. The transition by degrees, from a pointed conical pole 

 to an inclosed chamber, is, from the results described, very evi- 

 dent ; and so also is their connexion with those belonging to the 

 numerous neutral places produced under ordinary circumstances 

 (3234. figs. 6, 10, 11, 15). Not the slightest difficulty or hesi- 

 tation occurs, when these results are read or considered by the 

 principle of representative lines of force ; all the variations in 

 the strength of the magnetic force and in the direction appear 

 at once. But the great point is to observe how they all concur 

 in showing the necessity of the complete and equivalent dual 

 relation of the magnetic forces. When that is diminished or 

 interfered with in any degree, in the same proportion does the 

 power as a whole become diminished ; until, at last, it absolutely 

 disappears from a given place, though energies of the strongest 

 kind are directing the force on to that spot, supposing that one 

 of the dual elements could exist in any degree without, or inde- 

 pendent of, the other. 



3350. When formerly working with bismuth and magnets, I 

 described several results (2298. 2487. 2491.) due to the principle 

 of neutral magnetic places, more or less developed. If a sphere 

 or cube of bismuth be delicately suspended by a vertical suspen- 

 sion or on a torsion balance, and an N pole be brought 

 towards it, fig. 12, the bismuth will be re- 



pelled and the suspension deflected: — if a &• * 



second N' pole be brought up, as in the '1 f 



figure, the bismuth will be less repelled by N N i ° i 11 



than before, will return towards it, and N' will 

 also seem to attract it, for on approaching 

 the bismuth will tend to go into the angle 

 formed by N and N'. If a third pole, N", be 

 brought up on the opposite side, the bismuth will then seem to 

 be attracted by it, and by the first pole, and will, in fact, return 

 very nearly into the position it would have if all the magnets 

 were away. I thought at one time that magnetic structure, given 

 by the second north pole N' to the bismuth, might produce the 

 approximation of it to N, and if so that this would be neutralized 

 by the action of a like pole N" on the opposite side, and so the 

 approximation of the bismuth (if due to such a cause) be pre- 

 vented. On the contrary, however, such a pole increased it; 

 and a moment's consideration, by showing that the three poles 

 form a chamber of diminished or no action (3341. 3347.), shows 

 also that such ought to be the case. All the movements of the 

 bismuth are the result of the tendency which it has to pass 

 from stronger to weaker places of magnetic action (2418.) ; and 



