.CIRCULAR COILS OF RECTANGULAR SFXTTION. 



127 



same value of c/b in a thick coil. The second order coefficients he gives are correct for 

 thick coils. 



In using the above formula with tables for the computation of L for valum of r/h 

 or b/c intermediate to those given in the tables, the value of / which is part of the 

 large or first order term will have to be obtained by interpolation, whereas in the 



TABLE III. 



method previously given, the whole of the first order term can be easily got with great 

 accuracy, by making use of the nearly constant ratio of r to b + c indicated by the 

 figures given in the third column of Table I. 



The coefficients /, / /,,, occurred in the computation of Tables I., II., and III., m, 

 and m a are the same as in these tables, and are in any case algebraic as 



m, = 



nt = 



2". 3. 5 



Table IV. gives the values of /, / and /, for different values of the ratio c'b for 

 thick coils, and of b/e for thin coils. 



3 I 2 



