﻿Bands 
  in 
  the 
  Positive 
  Band- 
  Spectrum 
  of 
  J^itrogen. 
  349 
  

   bands 
  of 
  nitrogen 
  (\ 
  = 
  500 
  to 
  \=280). 
  The 
  following 
  are 
  

  

  his 
  figures 
  : 
  — 
  

  

  

  

  

  

  

  |N. 
  observes 
  

  

  JST. 
  observes 
  

  

  N. 
  observes 
  

  

  N. 
  observes 
  

  

  N. 
  calcules 
  

  

  N. 
  observes 
  

  

  Intervalles 
  

  

  (Series 
  I.). 
  

  

  (Ser. 
  II.). 
  

  

  (Ser. 
  III.). 
  

  

  (Ser. 
  IV.). 
  

  

  (Ser. 
  IV.). 
  

  

  (Ser. 
  V.). 
  

  

  calcules. 
  

  

  

  

  

  183251 
  

  

  183241 
  

  

  201045 
  

  

  

  

  

  

  197360 
  

  

  197377 
  

  

  215179 
  

  

  14136 
  

   14428 
  

  

  

  

  193162 
  

  

  211792 
  

  

  211805 
  

  

  229578 
  

  

  14719 
  

  

  ... 
  

  

  188372 
  

  

  207770 
  

  

  226517 
  

  

  226524 
  

  

  244279 
  

  

  15010 
  

  

  ... 
  

  

  203388 
  

  

  222737 
  

  

  241518 
  

  

  241526 
  

  

  259316 
  

  

  15302 
  

  

  198776 
  

  

  218685 
  

  

  238080 
  

  

  256837 
  

  

  256828 
  

  

  274664 
  

  

  15593 
  

  

  214352 
  

  

  234256 
  

  

  253714 
  

  

  272444 
  

  

  272430 
  

  

  290247 
  

  

  15885 
  

  

  230247 
  

  

  250117 
  

  

  269587 
  

  

  288337 
  

  

  288315 
  

  

  306077 
  

  

  16-176 
  

  

  246374 
  

  

  266350 
  

  

  285791 
  

  

  304492 
  

  

  304492 
  

  

  322247 
  

  

  16468 
  

  

  262872 
  

  

  282831 
  

  

  302230 
  

  

  320946 
  

  

  320961 
  

  

  338707 
  

  

  16759 
  

  

  279636 
  

  

  299569 
  

  

  318990 
  

  

  337723 
  

  

  337721 
  

  

  355479 
  

  

  17051 
  

  

  296664 
  

  

  316628 
  

  

  336020 
  

  

  354772 
  

  

  354773 
  

  

  

  

  The 
  measurements 
  are 
  partly 
  by 
  Hasselberg, 
  partly 
  by 
  

   Lecoq 
  de 
  Boisbaudran, 
  and 
  partly 
  by 
  Deslandres 
  himself. 
  

   The 
  results 
  are 
  sufficiently 
  good 
  to 
  justify 
  his 
  claim 
  to 
  have 
  

   established 
  the 
  law, 
  though 
  in 
  many 
  instances 
  the 
  intervals 
  

   depart 
  widely 
  enough 
  from 
  the 
  figures 
  given 
  in 
  column 
  7. 
  

   Deslandres 
  states 
  that 
  he 
  has 
  verified 
  this 
  law 
  on 
  the 
  first 
  

   positive 
  group 
  of 
  nitrogen 
  (X 
  700 
  to 
  \ 
  500) 
  " 
  with 
  at 
  least 
  

   three 
  series," 
  and 
  on 
  other 
  spectra. 
  In 
  1890 
  Prof. 
  J. 
  S. 
  

   Ames 
  * 
  published 
  a 
  fresh 
  set 
  of 
  measurements 
  of 
  the 
  wave- 
  

   numbers 
  of 
  the 
  middle 
  line 
  in 
  the 
  head 
  of 
  the 
  bands 
  of 
  

   the 
  second 
  group 
  of 
  the 
  spectrum 
  of 
  nitrogen, 
  and 
  added 
  

   an 
  amended 
  table 
  of 
  the 
  series 
  picked 
  out 
  by 
  Deslandres. 
  

   The 
  following 
  are 
  his 
  figures, 
  with 
  the 
  addition 
  of 
  the 
  first 
  

   differences 
  between 
  the 
  wave-numbers 
  (p. 
  350). 
  

  

  The 
  regularity 
  of 
  the 
  first 
  differences 
  seems 
  to 
  prove 
  

   beyond 
  reasonable 
  doubt 
  that 
  we 
  have 
  here 
  the 
  expression 
  of 
  

   a 
  law 
  which 
  governs 
  the 
  bands 
  of 
  the 
  second 
  group. 
  

  

  So 
  far 
  as 
  I 
  am 
  aware, 
  however, 
  the 
  bands 
  of 
  the 
  first 
  

   group 
  have 
  never 
  been 
  reduced 
  to 
  order 
  in 
  the 
  same 
  way. 
  

  

  * 
  Phil. 
  Mag. 
  [5] 
  vol. 
  xxx. 
  p. 
  48. 
  

  

  