Unsymmetrical Components in the Stark Effect. 951 



we choose such combinations as give rise to m 3 — n s =0 

 or ?7i 3 — n 3 = ±1 respectively. The group in Table A corre- 

 sponds to lines where the plane of polarization is perpen- 

 dicular to the impressed field F [i. e. the electric force 

 parallel to F], and that of Table B to lines where the light 

 is polarized in a plane parallel to F [i. e. the electric force 

 perpendicular to F] . 



We observe that whereas (Pi — Qi) has a negative value 

 numerically equal to every one of its possible positive values, 

 (Q 2 — P 2 ) on the other hand has an invariable positive sign 

 and a roughly constant order of magnitude, viz. 10 3 . 



If we avail ourselves of the most recent values * for the 

 constants involved in the formula (25), viz. 



/i = 6'547 x lO" 27 , e = 4-774 x 10" 10 , — = 5-301 x 10 17 , 



m 



and if we put E = <? for hydrogen, we have 



K 1 = 5-784xl0 8 . K 2 = 7-677xl0; . . (28) 



so that (26) can now be written 



Av= 5-784 x 10 8 x Z x F + 7*677 xR.X 10 4 x F 2 , (29) 



where 7 - tj> m V _ Qg — Pg 



or on the scale of wave-lengths, since Av= —— 2 dX, 



- A\=-8304 x 10- 10 x F x Z + 1-102 x 10~ u x R,F 2 . (30) 



Here it must be remembered that F is measured in absolute 

 C.G.S. electrostatic unitss In (30) we observe that Z is a 

 whole number, positive or negative, between and 13 and 

 that R z varies from about \ to about 2. 



If we assume a value for F = 10 3 [ = 300,000 volt x cm.- 1 "], 

 then if \' be written for X x 10 8 \i. e. if we measure \', the 

 wave-length, in Angstrom units] we write : 



-AA/ = 8-304Z + 1-102 xE 2 (31) 



We thus see that for small values of Z, the second term 

 on the right-hand side of (31) is quite appreciable compared 

 with the first term [e. g. for Z = l the ratio is about £] ; and 



* These are quoted from E. A. Millikan's 'The Electron,' The 

 University of Chicago Press, Third Impression 1918, pp. 238 and 251. 



