159 



A Modified Permeameter. 



Edwin Morrison and B. D. Morris. 



In his work on the Magnetic Induction in Iron and Other ]\Ietals, Ewing 

 briefly describes a permeameter. (See page 247, Art. 148.) The instrument 

 is for the purpose of determining the magnetisation of a metal by means of 

 the tractive force. In Ewing's work the permeameter method constitutes 

 the fourth method of measuring the magnetic properties of a metal, that of 

 tlie ballistic, the direct magnetometric, and the optical methods having been 



r,<^. m. 



of Iro^ 



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previously described. After desci-ibing the apparatus and developing the 

 equations the author closes his discussion thus: "The tractive method is at 

 best inexact, but it affords a ready means of making rough measurements, 

 especially for purposes of comparison." 



