162 HENRY A. KOWLAND 



INDUCTION COILS 



The induction coils were in the shape of two parallel coils of nearly 

 equal size and of nearly square section. 



Let A and a he the mean radii of the coils. Let & he the mean 

 distance apart of the coils. 



Let 



C 



Supposing the coils concentrated at their centre of section we know that 



where F(c) and E(c) are elliptic integrals. 



If and y are the depth and width of each coil, the total value of 

 M will he, when A = a nearly, 



and we find 



nc 



(1 

 O -2 _ 12^ A 



^2 



COEBECTIONS 



Calling /? and <5 the scale deflections corresponding to tan a' and sin 

 , we may write our equation for the value of the resistance 



8 1--35 



where R' is the resistance of the circuit at a given temperature 17-0 C., 

 and E = 2^M-^ Ff (l + a -f & + etc.), in which ^, 5, etc. and a, 6, etc. 



are the variable and constant corrections respectively. 

 a. Correction for damping. 



