REFRACTIVE INDEX. 



12:5 



Suppose in/t=\ and ct=cd=^X)\ m.m. 

 and also /(=1.4 ; 



Then substituting in equation (3) A gives 



r/«/a: 



1-4 

 •0029+ 01 



xOl+01 



Since H and cd may each, be either positive or negative this gives 

 a maximum value of c////(=:-0129, which is an error ot 1.29 per cent. 



^6 



24 



ZZ 



20 



•D 

 V 1.4 



33 



2 12 



10 1.1 



12 



14 



1.6 



18 19 2.0 



Values of p 

 Fig. 3. 



