452 



DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 



There can be little doubt about these lines forming a series, but there is so far no 

 independent evidence that it is of the F type beyond its analogous position in the 

 spectrum to that of the other rare gases. If it is of this type we should expect to 

 find a number of parallel series as well as of the associated P type. It is then 

 necessary to test for these conditions. 



A considerable number of parallel series can be arranged all weak for m = 3 as in 

 the original series. Some of these are given in the following list in which the 

 numbers in clarendon below the wave-numbers give the separations from the corre- 

 sponding F lines. Those to the right of the vertical line are added. The others are 

 deducted. 



(2-67(0). ..71 



The wave-numbers in italics are by L.D. and subject to probable errors dX = -5 and possible d\ = 1. 

 For values of links see below. 



* u.26997-6 = 26891-0; 266948.e = 26891-8. 



t u.28927 = 28820-3; 28711.U = 28817-7, mean taken. 



} One at least must be a coincidence, or the two series can simply be linked by u or v. 



