440 BELL SYSTEM TECHNICAL JOURNAL 



and the 5-c<)liiinns, which in the sodium atom are widely separated, 

 are in the former atoms so closely crowded together that lines, which 

 in the sodium spectrum are far apart, are in the former spectra packed 

 into all-but-irresolublc groups. This is prol)able, but not certain. 

 Further data about other lines in the ionizcd-helium spectrum would 

 be gratefully received.-" 



The notation for the various "component" stationary states of the 

 ionized-helium atom is shown in Fig. 8. The successi\e columns 

 are denoted by the numerals 1, 2, 3, 4 . . . for which the general 

 symbol is k, as previously. This numeral is written as a subscript 

 to the serial number of the le\-el in its column, which commences with 

 1 in the first column, 2 in the second, 3 in the third, and so forth. 

 By inspecting the figure, the reader will see a reason for using these 

 ditTcrent values of the serial-number for the first levels of the different 

 columns. The serial-number is designated b\' n and called the total- 

 qiiantum-nmnber. The numeral k is called the azimiilhal-qitantum 

 number, as before. These hea\ily long names are imposed by the 

 theory and not by the data. 



E S. Further Analysis of the Stationary States of Other Elements than 

 Hydrogen and Ionized Helium; Multiplets 



Ha\ing performed a two-stage analysis of the spectra of ionized 

 helium and of hydrogen, we return to the spectra of the other elements 

 for a second attack. 



Let us consider the reasons for making these anahses in two stages. 



When the mid-Victorian physicist trained his spectroscope upon a 



tube full of glowing hydrogen, he saw the spectacle of Fig. 2 — the 



converging procession of distinct bright lines, of which the frequencies 



form that delightfully smooth numerical progression which we have 



already met. Later physicists with better instruments discovered 



that each of these "lines" was in fact a pair of lines. Now in strict 



iniiii, this discovery show'ed that the "lines" of the Balmer series 



were no lines at all; for a doublet is not a line. But the phj-sicists 



continued to refer to the "lines" of the Balmer series, chiefly no doubt 



because to anyone equipped with an ordinary spectroscope the doublets 



do appear as single lines. By itself this is little reason; but ilie usage 



is not altogether faulty. Few people w'ould hesitate lo admit that 



each of these doublets is not a couple of casual neighbors, not two 



'" It would be particularly interesting to settle beyond question whether the 

 niissinc lines demand the select ion-princi|)le already explained in section K4, rather 

 than tile one to be explained in section K8. This is one of the reasons for wanting 

 to produce and examine the spectrum of doubly-ionized lithium, in which the evi- 

 dence would probably be much clearer. 



