340 Mr. J. Buchanan oh the Theory of 



The "period" is R=0A. Taking OB = 1, the equation 

 to the graph of fig. 5 is 



4 f . 27T-U- . 1 . 27T aTT 1 . 27T.-P- . ) 



; a well-known expression. 

 Thus in general 



H{-~ A • Hfr-r VI)+ r ^--O-VS 



.,V 5 ' 



*{•■ r -»(5- 5 H-Vt)+--} 



To find the magnetic intensity of the residual magnetism, 

 make H= — . Thus from (12) we get 



The value H = R substituted in (12) will of course give 

 the same value of I r as does (13), but with the sign changed. 



Example 1. — Take a?=l, and R=180, in (13). Using a 

 4-figure mathematical table I find (13) gives approximately 



I,=|x0-66 



= 0-84. 



The convergence of (13) is extremely slow for this case. 



■p 

 Example 2.— Take #=1, 11=180, and H = j=45, in (12). 



I find A 



I = -x0'69 



7T 



= 0-87. 



Example 3— Take a? =4, and R=180 in (13). 

 Then 



I,.=-x0 e 57 



7T 



= 0-72. 



(12) 



