SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 209 



all. It should be noticed that as the iron rods become nearly saturated 

 with magnetism, the magnetization curves bend around and become 

 more and more parallel to the i/'-axis, so that a very slight displace- 

 ment of the curves up or down may result in proportionately large 

 errors in the construction of the ^-curves. The only thing to do is 



10 i& 



Figure 7. [Table III.] 



Reversal magnetization curves for a Bessemer soft steel rod of diameter 

 1.270 cms. 



to construct by " trial and error " methods a normal curve which will 

 give the best possible results for the whole body of iN'^-curves. 



To be absolutely consistent the ^V-curves should be constructed from 

 magnetization curves on the / vs. H' plane, for N is defined by 

 H = H'— NI. Substituting in this the value for / from the funda- 

 mental equation B = H -\- 47r/, we get 



H 



VOL. XLIII. 



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