400 Intelligence and Miscellaneous Articles. 



free ends of the loops, but is due to alterations of the magnetism, 

 owing to the alternate condensations and expansions, which are 

 greatest at the nodes and are null at the free ends. 



When the dynamometer was replaced by a galvanometer, ' the 

 needle of the latter exhibited no deflection, but only irregular move- 

 ments. These arose from the variations of the magnetic iron wire 

 inseparably connected with the rubbing ; for those actions took place 

 if the variations of the wire were produced without any note. It is 

 therefore to be concluded that the action upon the dynamometer is 

 to be ascribed to alternate opposite induction-currents of equal 

 strength, which indicate alternately opposite equal changes in the 

 magnetism. 



Of other commercial iron wires, of similar dimensions to that of 

 the wire previously used, two did not at all exhibit the phenomena 

 described on sounding, while another did so, but extremely feeble. 

 These wires were now heated in the middle, where a node was 

 formed when the fundamental note was sounded, and the experi- 

 ment was repeated. All three iron wires now exhibited the pheno- 

 menon in question so powerfully as to produce a deflection of 200- 

 300 divisions of the dynamometer. The wire used in the first 

 experiments, when heated at the node, gave also, when powerfully 

 rubbed, a deflection of 500-600 divisions. A steel wire, on the 

 contrary, after strong heating did not exhibit the phenomena in 

 question. Matteucci states, in accordance with these results, that 

 the magnetic moment of soft iron wires is more strongly changed 

 by drawing than is that of hard wires. 



To judge the strength of the effect obtained, it may be stated for 

 instance, that in one experiment, on opening the magnetizing spiral 

 (that is, by the almost total disappearance of the entire magnetism 

 of the iron), a current was induced in the induction -spiral which 

 only produced a deflection of three divisions in the dynamometer ; 

 while the action of the currents produced by continuous sounding in 

 the induction-spiral was so far accumulated in the dynamometer that 

 the bifilar coil produced a deflection of an area of 460 divisions. 



An increase in the magnetism of the soft-iron wire, whether by 

 an increase of the current-producing elements or by using several 

 magnetizing spirals, gave no corresponding increase in the magnetic 

 variations on sounding. Just in like manner, in Villari's experi- 

 ments a strengthening of the magnetizing current was not always 

 succeeded by a stronger change of the magnetic moment in conse- 

 quence of traction ; and even when it was, only in the case of cer- 

 tain wires. 



When instead of two elements only one was used, feebler actions 

 were obtained ; but even when the magnetizing current was opened 

 the remanent magnetism of the soft iron wire was sufficient to 

 produce a deflection of from fifty to sixty divisions in the dynamo- 

 meter when the bar was made to sound. 



Considerably smaller variations of the magnetic moment were 

 indicated by the dynamometer in a node of the first upper tone of the 

 bar of 2600 vibrations in a second. — Monatsbericht der Berliner 

 Akademie, December 1869. 





