1891. 



of two Parallel Conductors. 



261 



Again taking the conductors touching one another, the follow- 

 ing table gives the maximum values of the correction as the 

 radius of the iron conductor increases. 



The first column expresses the radius of the iron conductor in 

 terms of that of the other ; the remaining columns are as in the 

 first table. 



The expression for the force can by suitably choosing a, a', b 

 so that b is somewhat greater than a */2, be made to change sign, 

 so that the force between the conductors would then be attractive, 



In the case of two iron conductors 

 L = fi +- 2/4, 



1 V M V 



1 °S^' + Xl °S(6'-a«)(&'-a'») 



l <Vlo ^ (62 - a2 - a,2) 



+ -A- 10 a (ft* _„»)(#< _ a '*) 



b 4 (b 2 -a*-a'y I 



+ A lo g(6«_ a *)(6»_ a '«)((6»_. a »)«_ a ^}((6*_ a «)»_ a ^] +etc -J ' 



/here 





In this series the coefficients of the powers of A. rapidly diminish. 

 It is perhaps worthy of remark that when /u, is 100 or greater, 

 the part depending on the size of the conductors and their 

 distance apart is only slightly affected by the value of /x, as A. 

 differs but little from unity. 



