Prof. G. Wiedemann's Magnetic Researches. 51 



citation* of earlier work, has (together with certain experi- 

 ments following at once from my views) reproduced my 

 theory as new. This theory has thus, in .various quarters, 

 been supposed to have originated with him. 



Mr. Hughes passes, for instance, alternating currents 

 through a flat iron band, surrounds the middle of this 

 with an induction-spiral, and, in a telephone connected with 

 the latter, hears no sounds ; as was to be expected, since, 

 with both directions of the current, the potential of the 

 transverse and circularly-directed molecular magnets upon 

 the spiral is zero. But if the iron band be twisted mean- 

 while, then, as I have expressly explained, the transversal 

 molecular magnets take up a position inclined to the axis 

 of the band, and partially maintain this position during 

 the detorsion. Hence, under the influence of the alter- 

 nating currents, they assume positions variously inclined to 

 the axis, so that the potentials can no longer be zero, or equal 

 to each other ; hence the telephone sounds. That upon the 

 sudden springing back of the twisted band the molecular 

 magnets may spring over to the other side, and that then the 

 induced currents run in the opposite direction, is clear. It is 

 equally obvious that the molecules of the iron tape may take 

 up an inclined position upon the lateral approach of a magnet, 

 though not spirally arranged round the axis, and that similar 

 phenomena must result. These conclusions follow at once from 

 my earlier results. 



Tn connexion with these and similar experiments,Mr. Hughes 

 proposes the theory (a) that each molecule of a magnetic metal 

 is an unalterable molecular magnet ; (b) that it can be caused to 

 revolve on its axis by means of mechanical and electromecha- 

 nical forces ; (c) that when there is external magnetic neu- 

 trality, the molecules and their polarities are so arranged that 

 they satisfy their mutual attractions in the shortest possible 

 way ; and, lastly, (d) that if magnetism is produced, the 

 molecules and their polarities become rotated into a given 

 direction in a symmetrical manner, so that a north pole is 

 produced in the one direction and a south pole in the opposite 

 direction. Moreover, also, a symmetrical arrangement is as- 

 sumed when magnetism is produced, but the circuits of attrac- 

 tion are not complete unless there is a keeper connecting the 

 two poles. Hence Mr. Hughes assumes still further (e) a 



* Thus, amongst others, the theoiy of rotation of molecular magnets, 

 given in De la Rive's Traite d' EUctriciie, English edition, Sect. iii. p. 317 

 (1853), is attrihuted to De la Rive ; the much earlier fundamental deduc- 

 tion of W.Weber, Electrodyn. Maashest. iii. p. c57 (1846) is not mentioned. 

 My conclusions are not quite correctlv represented. 



E 2 



