﻿258 
  Profs. 
  Wood 
  and 
  Kimura 
  on 
  the 
  

  

  Eleventh 
  Order. 
  Thirteenth 
  Order* 
  

  

  X. 
  

  

  1 
  

  

  X. 
  

  

  1 
  

  

  

  X 
  

  

  

  X 
  

  

  622879 
  

  

  160545 
  

  

  6388-24 
  

  

  156538 
  

  

  3144 
  

  

  477 
  

  

  92-14 
  

  

  442 
  

  

  36'12 
  

  

  356 
  

  

  92-82 
  

  

  425 
  

  

  *6237-68 
  

  

  316 
  

  

  9454 
  

  

  383 
  

  

  *6239-56 
  

  

  268 
  

  

  *6396-08 
  

  

  346 
  

  

  42-0 
  

  

  205 
  

  

  *6398-05 
  

  

  297 
  

  

  Twelfth 
  Order. 
  

  

  Fifteenth 
  Order. 
  

  

  6294-87 
  

  

  158859 
  

  

  1-6545-65 
  

  

  152773 
  

  

  99-40 
  

  

  745 
  

  

  t6552-19 
  

  

  621 
  

  

  t6303-71 
  

  

  636 
  

  

  59-05 
  

  

  461 
  

  

  08-57 
  

  

  514 
  

  

  *6560-56 
  

  

  426 
  

  

  t6309-99 
  

  

  479 
  

  

  *6562-64 
  

  

  378 
  

  

  *6316-16 
  

  

  324 
  

  

  

  

  *6318'14 
  

  

  274 
  

  

  Seventeenth 
  Order 
  

  

  196 
  

  

  237 
  

  

  t6714-00 
  

  

  148923 
  

  

  

  

  •I-6721-03 
  

  

  787 
  

  

  

  

  *6731-09 
  

  

  564 
  

  

  

  

  *6733'27 
  

  

  516 
  

  

  Excitation 
  by 
  the 
  Yellow 
  Lines. 
  

  

  We 
  have 
  measured 
  the 
  wave-lengths 
  of 
  the 
  lines 
  in 
  the 
  

   resonance 
  spectrum 
  excited 
  by 
  the 
  yellow 
  lines 
  of 
  the 
  Cooper- 
  

   Hewitt 
  arc, 
  and 
  the 
  quartz 
  arc 
  operating 
  at 
  115 
  volts. 
  The 
  

   values 
  given 
  in 
  the 
  following 
  table 
  are 
  on 
  the 
  International 
  

   Scale 
  and 
  reduced 
  to 
  vacuum. 
  They 
  were 
  determined 
  from 
  

   plates 
  made 
  with 
  the 
  plane 
  grating 
  and 
  Cooke 
  lens 
  of 
  1 
  metre 
  

   focus, 
  and 
  can 
  be 
  considered 
  correct 
  only 
  to 
  about 
  0*1 
  AIL 
  

   We 
  have, 
  however, 
  made 
  some 
  measurements 
  of 
  the 
  doublets 
  

   photographed 
  with 
  the 
  3-metre 
  lens, 
  which 
  are 
  correct 
  pro- 
  

   bably 
  to 
  0'02 
  AIL, 
  and 
  as 
  the 
  same 
  irregularities 
  were 
  

   found 
  in 
  the 
  spacing, 
  we 
  have 
  not 
  thought 
  it 
  worth 
  while 
  

   to 
  measure 
  the 
  complete 
  spectrum 
  to 
  the 
  highest 
  degree 
  of 
  

   accuracy. 
  

  

  The 
  wave-lengths 
  are 
  given 
  in 
  the 
  following 
  table. 
  The 
  

   lines 
  or 
  doublets 
  excited 
  by 
  the 
  Cooper-Hewitt 
  lamp 
  are 
  

   marked 
  thus 
  *. 
  

  

  The 
  series 
  excited 
  by 
  the 
  Cooper-Hewitt 
  lamp 
  in 
  the 
  case 
  

   of 
  the 
  5769 
  line 
  differs 
  from 
  that 
  excited 
  by 
  the 
  green 
  line 
  

   in 
  a 
  number 
  of 
  respects. 
  

  

  In 
  the 
  first 
  place, 
  at 
  the 
  point 
  of 
  excitation 
  we 
  have 
  only 
  

   the 
  R.R. 
  line 
  with 
  no 
  companion. 
  At 
  orders 
  1, 
  2, 
  3, 
  6, 
  and 
  

   9 
  we 
  have 
  doublets, 
  4 
  and 
  8 
  are 
  missing, 
  and 
  at 
  5, 
  7, 
  and 
  10 
  

   we 
  have 
  single 
  lines. 
  

  

  