Multilayer Coils with Square and Circular Section. 989 

 Substituting (26) into (31) and (34), 



1- 2 



p, 



Co -^T7F^ (35) 



8= i 4^—1 



Thus formulae (20), (31), (35) give C ', C ", C "v 

 Hence C is obtained as 



The expression for C / is in a form suitable for numerical 

 computation. It remains to transform (31) and (35) into 

 more convenient expressions. 



This may be done by formula (26), which gives 



p s _ cl^J 2 



A 



2 ,4 

 An expression for -r- may now also be obtained in a 



TT 



different form by making v = — -, in (25). This gives 

 for x y which is equal to a for the above value of v, 



so that 



In this series the terms are alternately positive and 

 negative, so that the error committed is always less in 

 absolute value than the last term left out. Thus, takino- 

 the first six terms of the series (37), the error committed is 

 less than O'OOl. A calculation gives 



1=0-847 (37 a> 



The value of -j- thus being known, the double series 



(4*i-l)(4*i-f4j a -2) 



which occurs in (31) will be expressed in terms of X — — 



V 



