544 Prof. Wartmann on the Musical Sounds 



observed facts of earthquake motions, or even with the condi- 

 tions of his own hypothesis. 



LXXXIII. On the Causes to which Musical Sounds produced 

 in Metals by discontinuous Electric Currents are attributable. 

 By Prof. Elie Waktmann*. 



QINCE the discovery made in 1837 by Dr. Page, and veri- 

 *-* fied the following year by Prof. Delezenne, of the possi- 

 bility of producing a musical sound by electricity, this interest- 

 ing phenomenon had scarcely been studied, when in 1844 

 MM. Marian, Beatson, Gassiot, and De la Rive all at once 

 made known the various conditions of its production. The 

 interesting memoir of the last gentleman, printed in vol. v. 

 p. 500 of the Archives de I'Electricite, contains a great num- 

 ber of very valuable results. But the theoretical part of the 

 subject has not yet been presented under a precise and gene- 

 ral form, and it is with a view to supply, if possible, this gap, 

 that I have undertaken the following experiments. I imagined 

 them in the month of August 1845, in consequence of a meet- 

 ing at which M. de la Rive exhibited his curious apparatus to 

 Prof. Dove and myself. 



A well-annealed soft-iron wire, l m, 7 long and 2 mm, 5 in dia- 

 meter, was fixed in a horizontal position on a thick trencher 

 of hard wood inserted into the wall. One of its extremities 

 was held back by the jaws of a clamp, whilst the other sup- 

 ported a weight of 24 kilogrammes. Upon a cork, pierced by 

 friction with the wire, I arranged a small plane mirror, with 

 parallel faces, made at the Optical Institute of Munich and 

 intended to reflect, into a telescope furnished with cross wires, 

 the divisions of a scale placed at a distance of two metres. 

 This arrangement, similar to that of the magnetometer, ex- 

 hibits the least deviations of the reflecting surface, when it is 

 not displaced parallel to itself. The iron wire passed through 

 a wooden reel, the bore of which was five centimetres in dia- 

 meter, and on which were rolled three copper wires enveloped 

 with silk, 23 m, 6 long and 3 millimetres in diameter. I em- 

 ployed a Bunsen's battery of eleven pairs, and a mercurial 

 rheotome or contact-breaker ; these two instruments were en- 

 closed in an ante-room adjoining the laboratory. 



According to the place which the wire occupies, it becomes 

 the seat of greater or less transversal vibrations, whose plane 

 may be varied at will. In general, in any position of the wire, 

 the intensity of the effect varies at different points of its length, 

 as is perceived on bringing the mirror to such points. The 

 * Communicated by the Author. 



