Ferromagnetic Wires in a Magnetizing Field. 65 L 



increase with tension. By altering the length of the ferro- 

 magnetic wire, the positions of the maxima and minima are 

 imperceptibly affected. 



These positions of the maxima and minima do not coincide 

 with those in the former experiment, the first maximum 

 occurring at a little higher frequency, and the second at a 

 considerably lower frequency. The first maximum is also of 

 a frequency higher by at least 2*5 times than that calculated 

 on the consideration that the phenomenon is due simply to 

 the elastic vibration of the wire. 



Instead of attaching a weight to the free end of the wire, 

 the same end was stretched by means of a spiral spring fixed 

 to the stand. Varying the frequency of the intermittent or 

 alternate current, the maxima and minima of the amplitude 

 of vibration were also observed, as shown in figs. 4 and 5. 



Fig. 4. — Iron Wire. 



In this case, the first maximum occurred at a frequency of 

 about 75 per second for iron as well as for nickel, and the 

 second at a frequency higher than 160 per second for these 



