for Production of Luminosity in Atmospheric JSeon. 937 



(2, p — m, s) and (2, p — m, d), or subordinate series, types. 

 On the Bohr-Sommerfeld theory, spectrum lines have their 

 origin in the movements of an electron within an atom 

 from one temporary position of stability (or temporary 

 orbit) to another, in which the energy of the system is- 

 smaller. Thus the series of lines (1'5, s — m,p) result from 

 the return of an electron to the 1*5, s position of stability- 

 after having been displaced to one of the positions de- 

 signated by 2p, Zp, 4ip, &c. It is generally assumed 

 that when an atom is ionized and subsequent recombination 

 takes place, the electron, in returning to the orbit normally 

 occupied, may stop temporarily in any of the intermediate 

 stable orbits. In falling between any two temporary 

 positions it causes the system to emit a radiation, the- 

 frequency of which corresponds to the energy differences 

 between these two positions. Thus, when recombination 

 takes place on a considerable scale, a spectrum consisting of 

 lines corresponding to all possible displacements should 

 result. The appearance of one set of lines at the ionization 

 velocity 20 volts, and another set of lines at 22'8 volts, 

 therefore indicates either that two entirely different elements 

 are being ionized at these two velocities, or that displacements 

 between quite different orbits in similar atoms are occurring. 

 In order to distinguish between these two possibilities, it is 

 necessary to ascertain whether there exists any close relation- 

 ship between the constants of the particular subordinate 

 series of which members appear when the highest ionization 

 velocity is passed, and the constants of the particular prin- 

 cipal series of which lines appear at 20 volts. A consideration 

 of Table IV. given below shows that there are instances in 

 which lines of the series (1"5, s — m, p) appear at 20 volts, 

 and lines of the corresponding (2, p — m, s) series do not 

 appear until the electron velocity reaches 22'S volts. 





Table 



IV 







Instances of lines of 



series 1*5, s—m, p 



appearing at 20 volts. 





Instances 



corresponding 



appearing 



! 



A. 

 5222 

 5298 

 5189 



of lines of the 

 ; 2, p—m, 8 series 

 at 22-8 volts. 



A 



\. 

 6507 

 6678 

 6402 



Series. 

 1-5,34-2,^ 



1-5, s 5 -2, p Q 



Series. 

 2, 2? 8 -4-5, s 4 



2^,-4-5.^ 

 2.^,-4-5, s 5 



Each column of the table includes lines of the two type! 

 of series found by Paschen to occur in the neon spectrum 



