484' Dr. R. Hare's Objections to the Theories severalli/ of 



namic induction is consistently explained, by supposing that 

 the waves of polarization, in passing along one conductor, pro- 

 duce, pari passu, the opposite polarization in the proximate 

 part of any neighbouring conductor suitably constituted, si- 

 tuated and arranged to allow it to form a part of a circuit. 



73. It is only during the state of the incessant generation 

 and destruction of what has been called the two electricities, 

 that the circuit, which is the channel for the passage of the 

 polarizing waves, is endowed with electro-magnetic powers. 

 It was, no doubt, in obedience to a perception of this fact, 

 that Oersted ascribed the magnetism of a galvanized wire to 

 a conflict of the electricities. Undoubtedly that state of a 

 conductor in which, by being a part of an electrical circuit, it 

 becomes enabled to display electro-magnetic powers, is so far 

 a conflict of the two electricities, as the affections of matter, 

 which are denominated electrical, consist of two opposite polar 

 forces, proceeding, agreeably to the language of Faraday, in 

 opposite directions from each side of the source, and conflict- 

 ing with each other so as to be productive of reciprocal an- 

 nihilation. 



74. That a corpuscular change in conductors is concomi- 

 tant with their subjection to, or emancipation from, a galvanic 

 current, is proved by an experiment of Henry's, which he 

 afforded me an opportunity, on one occasion, of witnessing. 

 I allude to the fact that sound is produced whenever the cir- 

 cuit is suddenly made or suddenly ruptured. By I. P. Mar- 

 rian it has been observed, that a similar result takes place 

 during the magnetization or demagnetization of iron rods, by 

 the alternate establishment or arrestation of galvanic dis- 

 charges through wires coiled about them so as to convert each 

 into an electro-magnet. Mr. Marrian represents the sound 

 as resembling that produced by striking a rod upon one of 

 its ends*. Sounds from this source were observed by Dr. 

 Page in 1838. See Silliman's Journal for that year, vol. 

 xxxiii. 



75. Thus it appears that there is an analogy between the 

 state of matter which involves permanent magnetism, and that 

 which constitutes a galvanic current, so far as this ; that either 

 by one or the other, during either its access or cessation, an 

 affection of the ponderable particles concerned ensues, suffi- 

 cient to produce sound. 



76. Simultaneously with the production of sounds as above 

 stated, by the opening or closing of the galvanic circuit through 



* Agreeably to recent experiments of Faraday, the panicles of a glass 

 prism may be so influenced by an electro-magnet as to affect the passage 

 of polarized light. See Phil. Mag. and Journ., vol. xlv. p. 383, 1844. 



