﻿18 
  MALLET: 
  VOLCANOES 
  OF 
  BARREN 
  ISLAND 
  AND 
  NAHCONDAM. 
  

  

  piece), 
  a 
  conspicuous 
  object 
  against 
  the 
  sky-line. 
  Dr. 
  Playfair, 
  who 
  

   landed 
  in 
  185 
  7, 
  refers 
  to 
  this 
  block,, 
  which 
  was 
  also 
  noticed 
  by 
  Mr. 
  "Ball 
  

   in 
  1873. 
  1 
  

  

  Of 
  several 
  solfataras 
  in, 
  and 
  close 
  to, 
  the 
  crater, 
  the 
  largest 
  is 
  that 
  

   Solfataras 
  at 
  the 
  re- 
  extending 
  from 
  the 
  northern 
  edge 
  downwards 
  into 
  

   the 
  interior. 
  It 
  is 
  somewhat 
  in 
  the 
  shape 
  of 
  a 
  

   triangle 
  with 
  the 
  apex 
  pointing 
  downwards 
  having 
  a 
  base 
  of 
  about 
  50 
  feet 
  

   and 
  perpendicular 
  of 
  some 
  80. 
  Throughout 
  the 
  greater 
  portion 
  of 
  this 
  

   area 
  the 
  ground 
  wa&, 
  at 
  the 
  time 
  of 
  my 
  visit, 
  2 
  covered 
  by 
  a 
  crust 
  of 
  

   sulphur 
  varying 
  from 
  2 
  or 
  3 
  to 
  6 
  or 
  8 
  inches 
  in 
  thickness. 
  In 
  one 
  or 
  

   two 
  spots 
  there 
  was 
  as 
  much 
  as 
  a 
  foot. 
  The 
  sulphur 
  had 
  a 
  columnar 
  

   structure 
  perpendicular 
  to 
  the 
  surface 
  of 
  the 
  crust, 
  the 
  surface 
  being 
  

   generally 
  formed 
  by 
  an 
  infinitude 
  of 
  small 
  glittering 
  crystals. 
  The 
  ash 
  

   beneath 
  (which 
  was 
  dug 
  into 
  to 
  a 
  depth 
  of 
  6 
  feet) 
  contained 
  some 
  

   sulphur 
  disseminated 
  very 
  irregularly 
  through 
  it, 
  and, 
  from 
  its 
  normal 
  

   black 
  color, 
  was 
  bleached 
  to 
  a 
  greyish-white 
  through 
  the 
  influence 
  of 
  acid 
  

   vapors. 
  From 
  crevices 
  between 
  some 
  ejected 
  blocks, 
  near 
  the 
  middle 
  of 
  

   the 
  solfatara, 
  superheated 
  steam, 
  with 
  sulphureous 
  vapor, 
  issued 
  rather 
  

   copiously, 
  the 
  column, 
  as 
  it 
  rose 
  into 
  the 
  air, 
  being 
  visible 
  from 
  the 
  

   landing-place, 
  or 
  even 
  some 
  distance 
  out 
  at 
  sea. 
  The 
  temperature 
  of 
  

   the 
  steam 
  at 
  the 
  point 
  of 
  issue 
  was 
  219° 
  F., 
  or 
  9° 
  above 
  the 
  boiling 
  

   point 
  of 
  water 
  at 
  the 
  elevation 
  of 
  the 
  crater, 
  and 
  the 
  fumes 
  were 
  

  

  i 
  Dr. 
  Playfair 
  says 
  that 
  the 
  longest 
  direction 
  of 
  the 
  crater, 
  in 
  1857, 
  lay 
  N. 
  W. 
  — 
  S. 
  E., 
  and 
  

   Mr. 
  Ball, 
  writing 
  in 
  1873, 
  makes 
  a 
  similar 
  statement. 
  Lieutenant 
  Henthcote, 
  again, 
  who 
  

   accompanied 
  Dr. 
  Playfair 
  (vide 
  Mouat's 
  Researches 
  amongst 
  the 
  Andaman 
  Islanders, 
  p. 
  53) 
  

   calculated 
  the 
  height 
  of 
  the 
  cone, 
  trigonometrically, 
  at 
  975 
  feet 
  above 
  the 
  sea 
  (Selec, 
  Rec. 
  

   Govt, 
  of 
  India, 
  XXV, 
  p. 
  128), 
  or 
  40 
  feet 
  lower 
  than 
  Captain 
  Hobday's 
  value, 
  from 
  which 
  it 
  

   might 
  be 
  inferred 
  that 
  the 
  cone 
  has 
  gained 
  40 
  feet 
  since 
  1857- 
  But 
  tbe 
  descriptions 
  of 
  the 
  

   crater 
  by 
  Dr. 
  Playfair, 
  Dr. 
  Leibig, 
  and 
  Mr. 
  Ball, 
  especially 
  by 
  the 
  last-named, 
  agree 
  so 
  well 
  

   with 
  its 
  present 
  appearance, 
  that 
  it 
  is 
  extremely 
  difficult 
  to 
  believe 
  that 
  an 
  eruption 
  has 
  occurred 
  

   since 
  their 
  time, 
  by 
  which 
  the 
  direction 
  of 
  the 
  major 
  axis 
  has 
  been 
  shifted 
  some 
  60°. 
  It 
  is 
  

   plain, 
  also, 
  from 
  Dr. 
  Playfair's 
  view 
  of 
  the 
  island, 
  and 
  the 
  copy 
  of 
  a 
  photograph 
  given 
  at 
  

   p. 
  9 
  of 
  the 
  same 
  volume, 
  that 
  the 
  western 
  depression, 
  aud 
  the 
  great 
  ejected 
  block, 
  were 
  in 
  the 
  

   same 
  position 
  as 
  at 
  present. 
  The 
  position 
  of 
  the 
  block 
  seems 
  to 
  furnish 
  almost 
  incontestable 
  

   proof 
  that 
  the 
  altitude 
  of 
  the 
  cone 
  is 
  the 
  same 
  now 
  as 
  in 
  1857. 
  

  

  2 
  1 
  say 
  " 
  was 
  " 
  because 
  the 
  richest 
  part 
  of 
  the 
  sulphur 
  was 
  collected 
  and 
  removed 
  by 
  the 
  

   party 
  of 
  convicts 
  placed 
  at 
  my 
  disposal. 
  

  

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  268 
  ) 
  

  

  