﻿198 Mr. IS. McCleland on the Absorption Spectra of 

 The coefficients used are given in the following table : — 

 x y I v 



X 



i 



m 



f 



9 



y 



m 



J 



9 



f 



i 



f 



9 



h 



m Y 



V 



9 



f 



m l 



h 



Proceeding as before, we find that the frequency equation 

 breaks up into the two equations 



[Q+m)p^c}[{l 1 -hm 1 )p 2 -c 1 -]=(f+g)Y - (viii.) 

 [(l-m)f-eMh-™i)p*-c{\=<J-g)Y - (ix.) 

 and the characteristic equations reduce to 



X[{(l+m)p'-ri P -c}{(l 1 + m l )p^r 1 L P -c 1 }^(f+ 9 )Y] 



= —E[l 1 + m 1 )2f — {f+g)p 2 -r l tp — c 1 ~] (x.) 



and a similar equation for H. 



It can be seen that equations (viii.) and (ix.) correspond to 

 equations (v.), and (x.) to (vii.), the difference being in the 

 induction coefficients only. Now (v.) and (vi.) are the 

 equations of the [x, £) (or ?/, tj) group independently (allowing 

 for the change of notation). 



It appears from the above that the four bands of the 

 system may be looked on as derived from the two bands of 

 either group by displacement. This in the case of the bands 

 given by (viii.) is toward the regions of greater wave-lengths, 

 and the bands produced by the displacement in this direction 

 will tend to be sharpest. The direction of displacement of 

 the bands given by (ix.) depends on the relative values of 

 the various coefficients. It appears, then, that the groups 

 affect one another in the same general way as simple 

 oscillation centres. 



Thus, for example, a group which gives two bands A, B 

 (fig. 1) will give rise to four bands, C, D, E, F, when 

 associated with a similar group, and the appearance of the 

 curve will be as in fig. 2. 



If m is small, C and E may coalesce to form a single broad 

 band. 



We have seen that the band C is likely to be sharp, while 

 F may be very diffuse. This, it is suggested, is the so- 

 called general absorption, which is really part of a diffuse 

 band in the most refrangible regions ? . 



