﻿30 
  MALLET 
  : 
  VOLCANOES 
  OF 
  BARREN 
  ISLAND 
  AND 
  NARCONDAM. 
  

  

  with 
  some 
  simple 
  method 
  of 
  purification/ 
  he 
  might 
  be 
  able 
  to 
  work 
  out 
  the 
  

   deposits 
  at 
  a 
  profit. 
  Firewood 
  for 
  distilling" 
  the 
  sulphur 
  is 
  abundant. 
  But, 
  

   on 
  the 
  other 
  hand, 
  the 
  present 
  want 
  of 
  good 
  water 
  on 
  the 
  island 
  is 
  a 
  difficulty 
  

   which 
  must 
  be 
  overcome 
  as 
  a 
  si?ie 
  qua 
  non 
  to 
  any 
  lengthened 
  stay 
  there. 
  

   There 
  is 
  an 
  unlimited 
  supply 
  of 
  fine 
  volcanic 
  ash, 
  or 
  ( 
  puzzuolana/ 
  

   on 
  the 
  island, 
  a 
  material 
  which 
  is 
  very 
  largely 
  used 
  

  

  Volcanic 
  ash 
  as 
  an 
  # 
  - 
  

   ingredient 
  of 
  hydraulic 
  in 
  Central 
  £ 
  ranee, 
  and 
  other 
  parts 
  or 
  lUirope, 
  as 
  an 
  

  

  mora1, 
  ingredient 
  of 
  hydraulic 
  mortar 
  or 
  cement. 
  It 
  is 
  

  

  obtainable 
  in 
  abundance 
  close 
  to 
  the 
  landing-place, 
  and, 
  if 
  it 
  could 
  bo 
  

   shipped 
  to 
  Port 
  Blair 
  at 
  a 
  sufficiently 
  low 
  rate, 
  would 
  be 
  worth 
  experi- 
  

   menting 
  on, 
  in 
  combination 
  with 
  the 
  lime 
  which 
  is 
  there 
  procurable. 
  3 
  

   In 
  conclusion, 
  I 
  may 
  perhaps 
  suggest 
  to 
  future 
  visitors 
  that 
  soundings 
  

   near 
  the 
  island 
  would 
  possess 
  considerable 
  interest, 
  

   as 
  at 
  present 
  we 
  have 
  no 
  certain 
  knowledge 
  as 
  to 
  

   the 
  depth 
  of 
  water 
  from 
  which 
  the 
  volcano 
  rises. 
  The 
  temperature 
  of 
  the 
  

   hot 
  spring 
  should 
  be 
  noted, 
  and 
  observations 
  made 
  on 
  the 
  thickness 
  of 
  the 
  

   fresh 
  and 
  undisturbed 
  sulphur 
  crusts. 
  What 
  was 
  left 
  after 
  our 
  visit 
  was 
  

   so 
  completely 
  trampled 
  down 
  by 
  the 
  working 
  party, 
  that 
  no 
  difficulty 
  

   ought 
  to 
  be 
  experienced 
  in 
  distinguishing 
  the 
  new 
  crusts 
  formed 
  since 
  

   February 
  1884. 
  From 
  their 
  thickness 
  an 
  estimate 
  can 
  be 
  formed 
  of 
  the 
  

   rate 
  at 
  which 
  the 
  sulphur 
  is 
  deposited. 
  The 
  recent 
  lava 
  streams 
  have 
  

   been 
  accurately 
  delineated 
  by 
  Captain 
  Hobday, 
  but 
  the 
  remaining 
  geo- 
  

   logical 
  lines 
  on 
  his 
  map 
  are 
  open 
  to 
  revision 
  in 
  detail. 
  As 
  Captain 
  

   Hobday 
  and 
  I 
  were 
  working 
  simultaneously, 
  his 
  map, 
  of 
  course, 
  was 
  not 
  

   available 
  for 
  geological 
  purposes 
  at 
  the 
  time. 
  The 
  lines 
  in 
  question, 
  

   therefore, 
  were 
  added 
  subsequently 
  from 
  my 
  notes, 
  made 
  on 
  a 
  rough 
  

   sketch, 
  kindly 
  supplied 
  me 
  by 
  Captain 
  Hobday 
  from 
  his 
  plane-table. 
  

  

  For 
  the 
  ascent 
  of 
  the 
  cone 
  the 
  best 
  route 
  from 
  the 
  landing-place 
  will 
  

   be 
  found 
  along 
  the 
  northern 
  edge 
  of 
  the 
  northern 
  lava 
  stream, 
  and 
  then 
  

   up 
  the 
  course 
  of 
  the 
  lava 
  itself 
  to 
  the 
  point 
  where 
  it 
  first 
  broke 
  out. 
  

   From 
  that 
  point 
  no 
  difficulty 
  will 
  be 
  experienced 
  in 
  reaching 
  the 
  summit. 
  

  

  1 
  Like 
  that, 
  for 
  instance, 
  practised 
  in 
  the 
  Suliinan 
  Hills, 
  where 
  one 
  ordinary 
  earthen 
  ghara 
  

   is 
  used 
  as 
  a 
  retort 
  and 
  another 
  as 
  a 
  receiver 
  (V. 
  Ball, 
  Records, 
  G. 
  S. 
  I., 
  Vol. 
  VII, 
  p. 
  158). 
  

  

  2 
  Records, 
  G. 
  S. 
  I., 
  Vol. 
  XVII, 
  p. 
  85. 
  

   ( 
  280 
  ) 
  

  

  