Phcenomena in Electro-Magnets. S8S 



some experiments in the hope that they may lead to further 

 investigation, as I am much inclined to think that many ex- 

 traordinary facts may be gathered as well as important results 

 obtained from a more extended prosecution of the subject. I 

 have already made a great number of experiments, and shall 

 proceed to detail a few of those which I consider to be the 

 most interesting. 



Having some considerable time since commenced a series 

 of experiments on the conducting powers of different metals, 

 among others I made use of several bars of soft iron, and 

 found that when a bar of that metal is so circumstanced that 

 it may be converted into an electro-magnet, at the instant 

 that the magnetism is imparled a sound is given from it, and 

 another sound is again perceptible when the galvanic current 

 is broken ; the two sounds however are not exactly alike, but 

 appear to correspond with such as may be produced by the 

 alternate separation and attraction of the particles or certain 

 particles composing the material acted upon. In order how- 

 ever that the subject may be more conveniently detailed, 1 will 

 describe a kvf experiments. 



I constructed a helix of thick copper wire, on the outside of 

 which is another of a much thinner wire, with such an arrange- 

 ment that they can be easily separated. I inserted a bar of 

 soft iron one inch in diameter and twenty feet long in the com- 

 pound helix, the primary wire of which I connected with a 

 battery; on breaking the circuit a very audible sound was 

 given from the iron, and again on forming contact. I then 

 took bars of different dimensions, and varying in thickness 

 from a quarter of an inch to two inches, and in length from 

 six inches to twenty feet, and a sound was given by each, va- 

 rying however in intensity ; first, according to the size of the 

 bar ; second, to its diameter, filling or not filling the helix ; 

 third, the power of the battery ; fourth, its position in the 

 helix ; for if the end were not placed beyond the centre of the 

 primary coil no magnetic effects were produced, and the bar 

 did not sound; and lastly, much appeared to depend on the 

 state of the secondary coil) as the sounds diminished consider- 

 ably on the ends being united, and the diminution was greater 

 when the contact was metallic, than when 1 held the wires in 

 my hands. The sound produced was the tonic of each bar, 

 and I could imitate it by striking the end of the bar with any 

 metallic substance, but could produce no resemblance by 

 means of a blow laterally. 1 used electrodes of different metals, 

 and tried numerous experiments in order to prove that the 

 sonorous effects were not produced by the jarring of the ap- 

 paratus ; one of these was the partial envelopment of the 



