1883.] Theory of Magnetism based on New Researches. 189 



molecules in steel are excessively rigid, they have the quality of 

 elastic rigidity, consequently the elastic pressure which prevented free 

 rotation serves to restore them quickly to their previous zero, and also 

 prevents any springing past or rotating from beyond their true zero. 



Effects of Magnetism. 



If the molecules of iron have inherent polarity and rotate freely 

 upon their axes, we should expect that we could rotate them by the 

 influence of an exterior permanent magnet alone, and this proves to be 

 the case, for if (when the rod is free from torsion and the molecules 

 are at zero) we approach a powerful compound permanent magnet 

 perpendicular to the rod, the molecules rotate under its influence as 

 freely as we have seen previously under torsion. Supposing the 

 magnet to be at 20 centims. distance, and that we gradually lessen this 

 distance, we find the maximum rotation whilst the magnet is at 

 5 centims., passing this point it gradually diminishes to a complete 

 zero when distant 3 centims. the molecules now being parallel with the 

 rod or the inducing coil according to the direction of rotation, and 

 consequently (as before explained) no induced currents are possible. 

 If we now continue to approach the magnet, the molecules are still 

 further rotated, and we have now strong induced currents of the 

 opposite polarity to the previous, notwithstanding that the rod is 

 evidently magnetised continually in the same sense. 



The rotation here, with its zeros and change of polarity, whilst the rod 

 is gradually magnetised by increasing degrees of magnetic force, is due 

 to the magnetic influence being perpendicular to the rod, allowing full 

 rotation, from the circular neutrality which I shall explain later ; but 

 if the magnet is approached in the line of the rod, instead of perpen- 

 dicular to it, we have continued increased rotation until it touches the 

 rod ; in this case we do not cross a zero, because the molecules can 

 only turn in the direction of saturation. 



Symmetrical Arrangement. 



When we have a rod of soft iron, free from torsion, it is perfectly 

 homogeneous in its structure, and we have a complete zero at all por- 

 tions of the wire, rod, or strip of iron, at the extremities as well as at 

 the centre. In order to observe this we should employ a very narrow 

 coil, the one employed by myself being a single insulated wire, wound 

 spirally upon itself upon a cardboard, being a marvel of workman- 

 ship, given. me by Mr. A. Stroh ; by means of this coil, whose thick- 

 ness does not exceed T x ¥ millim., we can explore rods of any length, 

 and if any portion is under strain we at once hear loud tones. Thus 

 I find in all rods that have not been annealed, spots or places show- 

 ing strains which have been caused by their mechanical treatment, 

 such as hammering, rolling, or drawing into wire. We can by this 



