781 
tion (5) in Art. 8., in the ease already dealt with in § 11 A. In 
the first column the wave-lengths X : are given in terms of the 
<p = <pß) 
Fig. 3. 
usual unit 10 -5 cm; in the;second, values of k calculated on the 
assumption, accepted in § 11 A, that 
yt 0 = 5 , 63 . 10~ 5 cm; (1) 
Bulletin III. 
3 
