BETWEEN LONGITUDINAL AND CIRCULAR MAGNETIZATIONS. 309 



TABLE XIII. 



SMALLER IRON TUBE. 



LARGER IRON TUBE. 



The theoretical values of the change of magnetization in the 

 above table were simply obtained graphically from the curves of 

 magnetization : o Ii fi om the longitudinal and o I2 from the 

 circular magnetization. With the smaller iron tube, the field 



due to axial current c at a point distant r from the axis was 



2c . 



calculated on the supposition that it is equal to —r- • This as- 

 sumption is evidently a rough approximation. 



