926 Prof. Horton and Miss Davies on Electron Velocities 



30 or 40 volts. These observations were repeated with 

 different pressures of neon in the apparatus — up to about 

 1*5 mm., — and at each pressure with various intensities of 

 the electron stream. With the filament at a high tempe- 

 rature and with about 40 volts potential difference between 

 the filament and the grid, the spectrum of the glowing gas 

 contained the lines given in the following table. The 

 relative intensities of the lines are also given, together 

 with the series to which they belong according to the 

 recent classification- of the lines of the neon spectrum by 

 Paschen *. 



Table I. 



Lines observed in the spectrum of the glow when 

 the electron velocity was about 40 volts. 



A. 



Intensity. 



Series. 



A. 



Intensity 



Series 



6717 



0-5 



1-5, s 2 % V , 



5764 



1 



2,p 9 ~4,d/ 



6678 



0-5 



1-5, s 2 -2 fi > 4 



5748 



05 



2,p 9 -4,d,' 



6599 



0-5 



1-5, s 2 -2,p 2 



5690 



0-5 



2,pi — 3'5, s 5 



6533 



0-5 



1-5, s 3 — 2, p 7 



5657 



0-5 



2,p 7 -3-5, V" 



6507 



2 



1-5, S4 -2 p 8 



5563 



0-5 



2, P s —35, s x " 



6402 



8 



l-o, s 5 -2,p 9 



540L 



3 



1*5, s< k -2,p l 



6383 



1 



1-5, s 4 -2,^ T 



5341 



3 



2,p iQ -4,d- 



6305 



0-5 



1-5, s 4 -2, p 6 



5331 



3 



2,p 1Q —4:, d 3 



6266 



2 



I'D, s 3 — -2, 2>5 



5298 



05 



2 i p i -4-5, s 2 



6217 



05 



1*5, s 5 — 2, p 7 



Some 



faint lines. 





6164 



1 



1-5, s 3 — 2, 2h 



5222 



1 



2, £> 8 —4'5, s i 



6143 



8 



l-5,s.-2,p e 



5204 



1 



2,p 6 -5, r// 



6096 



4 



V5,s i -2,p i 



5189 



2 



2, » q —4'5, s- 



6074 



4 



1-5, s i ~2,p., 



Some blurred lines. 



6030 



1 



l-5,s,-2,p-2 



5145 



2 



2,^ 4 -4-5, s/" 



5976 



1 



I'D, S- —2, p. 



5116 



2 



2, Pl0 -3-5,V' 



5945 



3 



l-5,s 5 --2,pl 



5080 



2 



2, j» 8 -5, ^ 4 



5852 



10 



1/5, s 2 -2, Pl 



5033 



3 



2,? 9 -5, d 4 ' 



5820 



0-5 



2,p,-A,d i 



4710 



1 





(Blurred.) 



It was found that the minimum electron velocity at 

 which a glow ever appeared in the gas was 20 volts. Over 

 the range of pressures investigated, the point at which the 

 glow appeared was independent of the pressure of neon 

 in the apparatus provided this was not too low (above about 

 0'05 mm.), but it was found to depend somewhat upon the 

 intensity of the electron stream, and also upon that of 

 the magnetic field used to concentrate the luminosity. In 

 general, as the speed of the electron stream was graduallv 

 raised, the brightest lines in the spectrum of the luminosity 



* F. Paschen, Ann. der Phi/sik, vol Ix. p. 405 (1919). 



