﻿Series 
  of 
  Lines 
  in 
  the 
  Spectrum 
  of 
  Neon. 
  981 
  

  

  were 
  respectively 
  1*3 
  mm. 
  and 
  0*02 
  ampere 
  ; 
  and 
  for 
  the 
  

   carbon 
  dioxide 
  tube 
  8'2 
  mm. 
  and 
  about 
  0*03 
  ampere. 
  

  

  In 
  conclusion, 
  I 
  have 
  pleasure 
  in 
  acknowledging 
  my 
  

   gratitude 
  to 
  Professor 
  Stroud, 
  who 
  has 
  provided 
  me 
  with 
  

   every 
  facility 
  necessary 
  for 
  the 
  successful 
  issue 
  of 
  the 
  ex- 
  

   periments 
  undertaken. 
  To 
  Mr. 
  H. 
  Morris-Airey_, 
  who 
  

   originally 
  suggested 
  to 
  me 
  the 
  examination 
  of 
  high-frequency 
  

   oscillatory 
  discharges, 
  I 
  owe 
  an 
  expression 
  of 
  thanks 
  also, 
  

   for 
  his 
  willingness 
  to 
  assist 
  in 
  any 
  matter 
  of 
  difficulty 
  which 
  

   arose 
  during 
  the 
  progress 
  of 
  the 
  work. 
  For 
  his 
  kindness 
  in 
  

   lending 
  me 
  an 
  argon 
  tube, 
  I 
  owe 
  my 
  further 
  thanks 
  to 
  

   Professor 
  Bedson, 
  of 
  Armstrong 
  College, 
  Newcastle. 
  

  

  Armstrong 
  College, 
  Neweastle-on-Tyne, 
  

   July 
  14, 
  1913. 
  

  

  LXXXVI. 
  Series 
  of 
  Lines 
  in 
  the 
  Spectrum 
  of 
  Neon. 
  

   By 
  R. 
  Rossi* 
  . 
  

  

  IT 
  has 
  been 
  shown 
  by 
  Runge 
  and 
  Paschen 
  f 
  that 
  the 
  line 
  

   spectrum 
  of 
  helium 
  can 
  be 
  grouped 
  into 
  six 
  series, 
  

   viz., 
  two 
  sets 
  of 
  a 
  principal 
  with 
  its 
  two 
  subordinate 
  series. 
  

  

  Similar 
  relations 
  were 
  looked 
  for 
  in 
  the 
  spectrum 
  of 
  neon 
  

   by 
  Watson 
  J, 
  who 
  failed 
  to 
  find 
  any 
  series 
  though 
  he 
  found 
  

   several 
  groups 
  of 
  lines 
  repeating 
  themselves 
  with 
  constant 
  

   frequency 
  difference. 
  

  

  On 
  further 
  examination 
  the 
  writer 
  has 
  found 
  three 
  series 
  

   of 
  lines 
  in 
  the 
  neon 
  spectrum 
  : 
  two 
  series 
  of 
  doublets 
  with 
  

   constant 
  frequency 
  difference 
  and 
  common 
  convergence 
  

   frequency 
  in 
  the 
  visible 
  spectrum, 
  and 
  one 
  series 
  of 
  single 
  

   lines 
  in 
  the 
  ultraviolet. 
  These 
  series 
  lines 
  are 
  rather 
  weak 
  

   compared 
  with 
  the 
  lines 
  forming 
  the 
  constant 
  frequency 
  

   difference 
  groups, 
  and 
  this 
  probably 
  accounts 
  for 
  their 
  being 
  

   overlooked 
  by 
  Watson. 
  

  

  As 
  the 
  lines 
  in 
  series 
  are 
  not 
  numerous, 
  Rydberg's 
  formula 
  

   was 
  adopted 
  ; 
  Kayser's, 
  and 
  Hicks' 
  modifications 
  otf 
  Ritz' 
  

   formula) 
  were 
  also 
  tried 
  and 
  better 
  agreement 
  between 
  

   calculated 
  and 
  observed 
  values 
  were 
  thereby 
  obtained, 
  but 
  

   they 
  have 
  the 
  disadvantage 
  of 
  requiring 
  one 
  more 
  constant. 
  

  

  The 
  wave-lengths 
  are 
  taken 
  from 
  Watson's 
  paper 
  §. 
  

  

  * 
  Communicated 
  by 
  Prof. 
  H. 
  F. 
  Newall, 
  F.R.S. 
  

   t 
  Astropliysical 
  Journal, 
  vol. 
  iii. 
  p. 
  4 
  (1896). 
  

   X 
  Astropliysical 
  Journal, 
  vol. 
  xxxiii. 
  p. 
  399 
  (1911). 
  

   § 
  Proc. 
  Roy. 
  Soc. 
  A. 
  vol. 
  lxxxi. 
  p. 
  181 
  (1908). 
  

  

  