﻿F. 
  A. 
  Per 
  ret 
  — 
  Volcanic 
  Research 
  at 
  Kilauea. 
  

  

  477 
  

  

  it 
  was 
  necessary, 
  for 
  the 
  sake 
  of 
  clearness, 
  to 
  greatly 
  exaggerate 
  

   the 
  size 
  of 
  the 
  trolley 
  and 
  the 
  height 
  of 
  the 
  A-frames 
  consti- 
  

   tuting 
  the 
  main 
  cable 
  supports, 
  with 
  the 
  unfortunate 
  result 
  of 
  

   reducing 
  the 
  apparent 
  dimensions 
  of 
  the 
  crater 
  to 
  an 
  almost 
  

   ludicrous 
  proportion 
  — 
  properly, 
  the 
  size 
  of 
  the 
  trolley 
  should 
  

   be 
  Jess 
  than 
  a 
  tenth 
  of 
  the 
  diameter 
  of 
  its 
  smallest 
  wheel, 
  as 
  

   drawn, 
  and 
  the 
  height 
  of 
  the 
  A-frames, 
  and 
  their 
  distance 
  from 
  

   the 
  crater's 
  edge, 
  should 
  be 
  reduced 
  in 
  proportion. 
  

  

  Fig. 
  2. 
  

  

  Fig. 
  2. 
  Showing 
  cables, 
  trolley, 
  and. 
  winch, 
  at 
  eastern 
  edge 
  of 
  the 
  crater. 
  

  

  A 
  -f-inch 
  Lidgerwood 
  steel 
  cable 
  with 
  hemp 
  core 
  was 
  

   employed, 
  the 
  total 
  length 
  between 
  anchorages 
  being 
  530 
  M. 
  of 
  

   which 
  nearly 
  400 
  M. 
  was 
  clear 
  span 
  between 
  A-frames. 
  This 
  

   was 
  stretched 
  to 
  a 
  5 
  per 
  cent 
  drop 
  according 
  to 
  recommenda- 
  

   tion 
  of 
  the 
  engineers,* 
  in 
  which 
  condition 
  the 
  center 
  of 
  the 
  

   span 
  hung 
  some 
  56 
  M., 
  at 
  the 
  beginning, 
  above 
  the 
  surface 
  of 
  

   the 
  lake, 
  the 
  subsequent 
  sinking 
  of 
  which 
  increased 
  this 
  con- 
  

   siderably 
  and 
  added 
  greatly 
  to 
  the 
  difficulty 
  of 
  lowering 
  the 
  

   instruments. 
  

  

  * 
  For 
  others 
  who 
  may 
  undertake 
  similar 
  experiments 
  the 
  writer 
  would 
  

   advise 
  a 
  greater 
  drop, 
  not 
  only 
  as 
  lessening 
  the 
  strain 
  but 
  as 
  actually 
  facili- 
  

   tating 
  the 
  sending 
  of 
  the 
  trolley 
  to 
  the 
  center 
  of 
  the 
  span. 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XXXVI, 
  No. 
  215. 
  

   32 
  

  

  -November, 
  1913. 
  

  

  