﻿Constitution 
  of 
  the 
  Mercury 
  Green 
  Line. 
  367 
  

  

  therefore, 
  the 
  vacuum 
  had 
  been 
  considerably 
  changed 
  ; 
  and 
  

   from 
  glimpses 
  that 
  were 
  obtained 
  at 
  times 
  of 
  what 
  seemed 
  

   to 
  be 
  further 
  lines, 
  it 
  appears 
  probable 
  that 
  the 
  full 
  com- 
  

   plexity 
  of 
  the 
  green 
  line, 
  when 
  unaffected 
  by 
  a 
  magnetic 
  

   field, 
  has 
  not 
  yet 
  been 
  disclosed, 
  and 
  can 
  only 
  be 
  investigated 
  

   under 
  peculiar 
  conditions 
  of 
  the 
  vacuum 
  in 
  the 
  tube, 
  and 
  

   possibly 
  of 
  the 
  action 
  of 
  the 
  discharging 
  coil." 
  

  

  Since 
  that 
  time 
  the 
  constitution 
  of: 
  the 
  green 
  line 
  of 
  

   mercury 
  has 
  engaged 
  the 
  attention 
  of 
  several 
  observers, 
  and 
  

   some 
  account 
  of 
  their 
  results 
  is 
  contained 
  in 
  the 
  paper 
  now 
  

   communicated. 
  It 
  remains, 
  however, 
  still 
  uncertain 
  what 
  

   are 
  the 
  conditions 
  which 
  govern 
  the 
  appearance 
  of 
  satellites 
  

   in 
  the 
  absence 
  of 
  an 
  impressed 
  magnetic 
  field. 
  Sometimes 
  

   these 
  satellites 
  are 
  apparently 
  absent 
  or 
  are 
  only 
  seen 
  with 
  

   great 
  difficulty 
  ; 
  at 
  other 
  times, 
  according 
  to 
  the 
  observations 
  

   referred 
  to 
  in 
  the 
  above 
  quotation 
  (observations 
  which 
  I 
  

   made 
  repeatedly) 
  they 
  flash 
  out 
  brightly 
  but 
  transiently 
  in 
  

   abnormal 
  complexity. 
  There 
  can 
  be 
  no 
  question 
  of 
  the 
  

   importance 
  of 
  research 
  into 
  the 
  governing 
  conditions 
  of 
  such 
  

   complexity 
  of 
  what 
  have 
  come 
  to 
  be 
  regarded 
  as 
  compara- 
  

   tively 
  simple 
  systems. 
  

  

  It 
  does 
  not 
  seem 
  impossible 
  that 
  some 
  of 
  the 
  discrepancies 
  

   among 
  the 
  estimations 
  of 
  wave-lengths 
  of 
  satellites 
  may 
  be 
  

   due 
  to 
  differences 
  in 
  conditions 
  of 
  production. 
  I 
  have 
  been 
  

   for 
  a 
  considerable 
  time 
  engaged 
  in 
  a 
  research 
  on 
  these 
  

   conditions, 
  but 
  so 
  far 
  it 
  has 
  proved 
  difficult 
  and 
  perplexing. 
  

   Now, 
  however, 
  with 
  a 
  ready 
  means 
  of 
  constructing 
  my 
  own 
  

   tubes, 
  I 
  have 
  some 
  hopes 
  of 
  obtaining 
  a 
  solution 
  of 
  the 
  

   problem. 
  

  

  The 
  paper 
  now 
  offered 
  describes 
  determinations 
  of 
  satellite 
  

   wave-lengths 
  which 
  have 
  been 
  made 
  during 
  the 
  last 
  year 
  in 
  

   the 
  course 
  of 
  this 
  research. 
  They 
  are 
  of 
  interest 
  in 
  them- 
  

   selves 
  ; 
  and 
  it 
  is, 
  moreover, 
  desirable 
  to 
  place 
  on 
  record 
  as 
  

   many 
  careful 
  measurements 
  of 
  these 
  lines 
  as 
  possible. 
  The 
  

   results 
  have 
  an 
  interesting 
  bearing 
  on 
  those 
  which 
  have 
  been 
  

   published 
  recently 
  by 
  McLennan, 
  Nagaoka 
  and 
  others, 
  and 
  

   which 
  are 
  referred 
  to 
  in 
  the 
  Comparative 
  Table 
  of 
  Wave- 
  

   lengths 
  given 
  at 
  the 
  end 
  of 
  the 
  paper. 
  

  

  Many 
  observers 
  have 
  studied 
  the 
  mercury 
  green 
  line 
  with 
  

   different 
  apparatus 
  and 
  using 
  various 
  sources, 
  and 
  there 
  has 
  

   been 
  not 
  a 
  little 
  lack 
  of 
  agreement 
  as 
  to 
  its 
  constitution. 
  

   The 
  experiments 
  here 
  described 
  were 
  undertaken 
  to 
  ascertain 
  

   the 
  reason 
  for 
  these 
  divergencies 
  by 
  observing 
  the 
  appearance 
  

   under 
  varying 
  conditions. 
  

  

  Apparatus. 
  — 
  The 
  spectroscopic 
  apparatus 
  used 
  in 
  the 
  first 
  

  

  