Elasticity of Ferromagnetic Substances by Magnetization. 463 



copper wire. The weight was dipped in water so as to avoid 

 its vibratory disturbance. The rotating cylinder with a 



Bar. 2. 



reflecting mirror, described in the preceding paper, was 

 brought in contact with the copper wire under slight pressure 

 to prevent sliding. The magnetizing coil was so long that 

 the bar lay in a nearly uniform field. The results of expe- 

 riment are given in fig. 3. Here H denotes effective field 



Fisr. 3 



«W 



and y the magnetic change of length per cm. We observe 



that the elasticity of a substance undergoing a large change 

 of length is also similarly affected by magnetization. 



