MEASUREMENT OF PERMEABILITY 



281 



resembling the magnetic hysteresis loop. The reader may easily 

 follow out the close analogies between the two systems. 



We have only attempted in this chapter to give such an account 

 of the magnetisation of the ferromagnetic metals that the reader 

 may gain a general idea of the methods of experiments and a 



FIG. 216. 



general id a of the results obtained. For details of the methods 

 and results, for effects of temperature and stress, and for modifica- 

 tions of the methods for technical purposes, the reader should 

 consult Ewing's Magnetic Induction in Iron and Other Metals on 

 which this chapter is based. That work is a very clear account by 

 one who has largely contributed to our knowledge of magnetic 

 phenomena. Additional information will be found in Rapports au 

 Congres International, 1900, vol. ii, in articles by H. du Bois and 

 E. Warburg. The latter contains some account of the various 

 changes in iron as the temperature rises, investigated by F. Osmond. 

 Another and a very full account of the present state of the subject 

 will be found in Winkelmann's Handbuch der Physik, vol. v. 

 Further information will be found in the paper by S. P. Thompson 

 referred to on p. 187. 



