332 Prof. F. L. 0. Wadsworth on the Resolving Power of 



more than 0*8 the intensity at the two maxima on each side, 

 we find that for resolution the distance between the com- 

 ponents in different cases must be 



10 = 01 j 



dist. = l-12« = n 1 , 



%0 = 2a, 



„ =i-45a=n 2 , 



tv = 3a, 



„ =r90«=X2 3 , 



w = 4a, 



„ = 2'45«=H 4 . 



For lines so wide that the broadening by diffraction can be 

 entirely neglected we find (fig. 6 b) that the distance between 

 the components necessary for resolution is 



Fig. 6 a. 



2-38=0-575«>^fw. 



Fig. 6 b. 



J.C O 1.0 ».o ». 



Expressing the preceding results in the form 

 Q, = ±w+f{w)a, 



we have 



for w = 0, 



for io = a, 



/(to) =1-00, 

 /(«>) = 0-55, 



fovw = 2a, f{w) =0-31, 



for to = 3a, f{io) = 0*18, 



for io= 4m, f(io) =0*15, 



for io = co a, f(w) = 0'00, 



o X 



l2r=a= — , 



7 o 



fl=^ + 0'3l| 



n=^+o-i8^, 



12=^ + 0-15t, 



n =^ioh-o-oo. 



The coefficients /(ic) of the last term are plotted in fig. 7 

 as a function of w. The first portion of this curve may, as in 



