﻿256 
  Profs. 
  Wood 
  and 
  Kimura 
  on 
  the 
  

  

  in 
  picking 
  out 
  other 
  series 
  of 
  doublets 
  in 
  the 
  series 
  of 
  com- 
  

   plicated 
  groups 
  excited 
  by 
  the 
  quartz 
  arc. 
  

  

  For 
  example, 
  we 
  may 
  take 
  the 
  wider 
  doublets 
  shown 
  

   united 
  by 
  dotted 
  lines 
  in 
  the 
  previous 
  paper 
  (fig. 
  4). 
  

  

  The 
  frequency 
  differences 
  for 
  these 
  doublets 
  are 
  given 
  in 
  

   the 
  following 
  table 
  : 
  — 
  

  

  Order. 
  

  

  Freq. 
  Dif. 
  

  

  Order. 
  

  

  Freq. 
  Dif. 
  

  

  

  

  161 
  

  

  8 
  

  

  158 
  

  

  1 
  

  

  159 
  

  

  10 
  

  

  157 
  

  

  3 
  

  

  159 
  

  

  12 
  

  

  157 
  

  

  5 
  

  

  158 
  

  

  15 
  

  

  152 
  

  

  6 
  

  

  157 
  

  

  17 
  

  

  156 
  

  

  It 
  will 
  be 
  remembered 
  that 
  the 
  frequency 
  difference 
  of 
  the 
  

   first 
  series 
  of 
  doublets 
  considered 
  was 
  50. 
  

  

  The 
  spacing 
  of 
  this 
  series 
  along 
  the 
  spectrum 
  is 
  only 
  fairly 
  

   well 
  represented 
  by 
  the 
  formula 
  

  

  1 
  m 
  (m 
  — 
  1) 
  

  

  r- 
  = 
  183075 
  - 
  2119 
  m 
  + 
  13—^0 
  — 
  • 
  

  

  The 
  observed 
  and 
  calculated 
  values 
  of 
  1/A, 
  for 
  the 
  com- 
  

   ponents 
  of 
  longer 
  wave-length 
  (the 
  companion 
  line 
  is 
  to 
  the 
  

   left 
  in 
  this 
  case) 
  are 
  given 
  in 
  the 
  following 
  table. 
  It 
  will 
  be 
  

   observed 
  that 
  the 
  doublets 
  are 
  missing 
  in 
  the 
  fourth, 
  eleventh, 
  

   and 
  thirteenth 
  orders, 
  as 
  well 
  as 
  in 
  the 
  orders 
  in 
  which 
  the 
  

   doublets 
  of 
  the 
  first 
  series 
  failed 
  to 
  appear. 
  

  

  Order. 
  I 
  (Obs.) 
  ^(Cal.) 
  Dif. 
  

  

  183075 
  183075 
  

  

  1 
  180956 
  180956 
  

   3 
  176754 
  176757 
  3 
  

  

  5 
  172599 
  172600 
  l 
  

  

  6 
  170543 
  170556 
  13 
  

   8 
  166470 
  166487 
  17 
  

  

  10 
  162448 
  162470 
  22 
  

  

  12 
  158479 
  158505 
  26 
  

  

  15 
  152621 
  152655 
  34 
  

  

  17 
  148786 
  148820 
  34 
  

  

  In 
  the 
  following 
  table 
  are 
  given 
  the 
  wave-lengths 
  and 
  

   their 
  reciprocals, 
  on 
  the 
  International 
  Scale 
  and 
  reduced 
  to 
  

   vacuum, 
  of 
  all 
  of 
  the 
  lines 
  in 
  the 
  groups 
  between 
  and 
  17, 
  

   in 
  the 
  case 
  of 
  iodine 
  vapour 
  excited 
  by 
  the 
  quartz 
  mercurv 
  

   arc 
  operating 
  at 
  115 
  volts. 
  

  

  The 
  doublets 
  excited 
  by 
  the 
  Cooper-Hewitt 
  lamp 
  are 
  

   marked 
  thus 
  * 
  and 
  the 
  other 
  doublets 
  which 
  we 
  have 
  studied 
  

   thus 
  t- 
  This 
  table 
  corresponds 
  to 
  the 
  diagram 
  in 
  the 
  pre- 
  

   vious 
  paper. 
  In 
  the 
  fourth 
  order 
  group 
  lines 
  A 
  and 
  B 
  were 
  

   added 
  from 
  an 
  old 
  series 
  of 
  measurements. 
  The 
  line 
  between 
  

   them 
  is 
  the 
  only 
  one 
  which 
  appears 
  on 
  our 
  recent 
  plates, 
  and 
  

   this 
  line 
  only 
  is 
  given 
  in 
  the 
  table. 
  

  

  