Combined Effect of Longitudinal and Circular 



Magnetizations on the Dimensions of 



Iron, Steel and Nickel Tubes. 



By 

 K. Honda, Rigakushi, 



Post-£;raduate in Plivsics. 



With Plates VIII. ami IX. 



1. The change of length in the direction of magnetization has 

 been made a subject of investigation by several experimentalists, 

 but few of them have measured the change in the direction per- 

 pendicular to that of magnetization. Joule^^ first observed the 

 diminution of length of an iron gas-piping by passing a current 

 through an insulated wire inserted into it, and bent over the 

 sides, so as to form a circular magnetizing coil of le convolutions. 

 His experiment was modified by BidwelP^ who measured the 

 change of dimensions in an iron ring. He found that the ring 

 becomes thicker in a strong field and thinner in a weak one. 

 From the measurement of the internal as well as the external 

 change of volume for iron, steel, nickel, and cobalt tubes, Knott^' 



1) Joule, Scientific papers I, 263. 



2) Bidwell, Proc. Eoy. Soc. 56, 94, 1895. 



3) Knott, Trans. Koy. Soc. 39, 457, 1898. 



