﻿BARREN 
  ISLAND. 
  SI 
  

  

  which 
  a 
  stick 
  could 
  be 
  thrust 
  for 
  8 
  feet. 
  From 
  the 
  mouth 
  steam 
  issued 
  

   rather 
  copiously 
  at 
  a 
  temperature 
  of 
  170° 
  : 
  it 
  had 
  no 
  action 
  on 
  either 
  lit- 
  

   mus 
  or 
  lead 
  paper. 
  In 
  crevices 
  of 
  the 
  lava 
  were 
  well-formed 
  aggregated 
  

   crystals 
  of 
  sulphur, 
  in 
  unmodified 
  rhombic 
  octahedrons 
  (P.) 
  From 
  the 
  

   point 
  of 
  issue 
  the 
  molten 
  rock, 
  after 
  reaching 
  the 
  base 
  of 
  the 
  cone, 
  flowed 
  

   down 
  the 
  valley, 
  and 
  over 
  the 
  previous 
  stream 
  from 
  the 
  south, 
  the 
  termin- 
  

   ation 
  of 
  the 
  later 
  current 
  being 
  marked 
  by 
  a 
  bank 
  a 
  little 
  to 
  the 
  west 
  of 
  

   the 
  foot 
  of 
  the 
  cone. 
  1 
  There 
  is 
  no 
  essential 
  difference 
  between 
  the 
  super- 
  

   ficial 
  part 
  of 
  the 
  lava 
  on 
  the 
  side 
  of 
  the 
  cone 
  and 
  that 
  in 
  the 
  valley 
  

   below 
  ; 
  both 
  are 
  about 
  equally 
  vesicular. 
  

  

  There 
  are 
  several 
  reasons 
  for 
  believing 
  that 
  the 
  lava 
  has 
  been 
  emitted 
  

   within 
  quite 
  a 
  recent 
  period, 
  almost 
  certainly 
  within 
  the 
  last 
  century. 
  

   The 
  absence 
  of 
  vegetation, 
  in 
  a 
  climate 
  where 
  foliage 
  grows 
  so 
  luxuriantly 
  

   where 
  once 
  it 
  has 
  established 
  itself, 
  as 
  on 
  the 
  lavas 
  of 
  the 
  outer 
  cone, 
  

   may 
  be 
  taken 
  as 
  one 
  indication 
  ; 
  while 
  the 
  rapid 
  cooling 
  of 
  the 
  hot 
  

   spring, 
  which, 
  as 
  I 
  shall 
  endeavour 
  to 
  show 
  further 
  on, 
  owes 
  its 
  existence 
  

   to 
  the 
  percolation 
  of 
  the 
  drainage 
  from 
  the 
  amphitheatre 
  through 
  the 
  

   still 
  heated 
  porous 
  materials 
  beneath 
  the 
  lava, 
  is 
  another 
  and 
  still 
  more 
  

   important 
  one. 
  Again, 
  Captain 
  Blair 
  makes 
  no 
  mention 
  of 
  the 
  lava, 
  an 
  

   object 
  so 
  prominent 
  that 
  it 
  could 
  not 
  possibly 
  escape 
  his 
  attention, 
  but 
  

   he 
  says, 
  " 
  The 
  volcano 
  was 
  in 
  a 
  violent 
  state 
  of 
  eruption, 
  bursting 
  out 
  im- 
  

   "mense 
  volumes 
  of 
  smoke, 
  and 
  frequently 
  showers 
  of 
  red-hot 
  stones. 
  

   u 
  Some 
  were 
  of 
  a 
  size 
  to 
  weigh 
  three 
  or 
  four 
  tons, 
  and 
  had 
  been 
  thrown 
  

   " 
  some 
  hundred 
  yards 
  past 
  the 
  foot 
  of 
  the 
  cone. 
  There 
  were 
  two 
  or 
  three 
  

   " 
  eruptions 
  while 
  we 
  were 
  close 
  to 
  it; 
  several 
  of 
  the 
  red-hot 
  stones 
  rolled 
  

   " 
  down 
  the* 
  sides 
  of 
  the 
  cone, 
  and 
  bounded 
  a 
  considerable 
  way 
  beyond 
  us." 
  

   If 
  the 
  stones 
  were 
  accompanied 
  by 
  finer 
  fragmentary 
  material, 
  such 
  

   ought 
  to 
  be 
  now 
  found 
  on 
  the 
  lava, 
  if 
  it 
  were 
  then 
  in 
  existence, 
  but 
  it 
  is 
  

  

  1 
  Dr. 
  Playfair's 
  plan 
  of 
  the 
  island, 
  as 
  seen 
  in 
  1857, 
  appears 
  to 
  represent 
  only 
  one 
  stream 
  

   of 
  lava, 
  flowing 
  from 
  the 
  northern 
  part 
  of 
  the 
  valley 
  into 
  the 
  sea. 
  Supposing 
  this 
  to 
  he 
  

   an 
  accurate 
  drawing, 
  Dr. 
  Playfair's 
  stream 
  must 
  have 
  been 
  buried 
  beneath 
  the 
  southern 
  and 
  

   northern 
  flows, 
  as 
  represented 
  on 
  Captain 
  Hobday's 
  map. 
  Dr. 
  Liebig, 
  however, 
  whose 
  visit 
  

   was 
  only 
  tbree 
  months 
  later 
  than 
  Dr. 
  Playfair's, 
  says 
  that 
  "surrounding 
  the 
  base 
  of 
  the 
  cone 
  

   the 
  bottom 
  of 
  the 
  valley 
  is 
  filled 
  with 
  black 
  masses 
  of 
  cold 
  lava." 
  (the, 
  italics 
  are 
  mine). 
  If 
  

   the 
  lava 
  had 
  been 
  less 
  than 
  three 
  months 
  old 
  it 
  would 
  have 
  been 
  still 
  red 
  hot, 
  at 
  the 
  sides 
  

   of 
  the 
  fissures, 
  and 
  probably 
  evolving 
  too 
  much 
  steam 
  to 
  escape 
  notice 
  {vide 
  foot-note, 
  p. 
  25). 
  

   The 
  accuracy 
  of 
  Dr. 
  Playfair's 
  plan 
  must, 
  I 
  think, 
  be 
  looked 
  upon 
  with 
  very 
  great 
  doubt. 
  

  

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