﻿322 
  REV. 
  R. 
  BARON 
  ON 
  THE 
  

  

  of 
  the 
  stones 
  these 
  quartz-crystals 
  are 
  all 
  coated 
  with 
  almost 
  

   microscopic 
  crystals 
  of 
  the 
  same 
  or 
  some 
  other 
  mineral, 
  so 
  that 
  they 
  

   look 
  as 
  if 
  they 
  had 
  been 
  frosted, 
  or 
  delicately 
  powdered 
  with 
  fine 
  

   white 
  flour. 
  The 
  crystals 
  of 
  others 
  assume 
  a 
  mamillated 
  form, 
  the 
  

   mamillae 
  being 
  covered 
  with 
  minute 
  crystals. 
  These 
  generally 
  

   present 
  a 
  delicate 
  blue 
  tint. 
  When 
  these 
  stones 
  are 
  broken 
  in 
  two, 
  

   the 
  hemispheres 
  appear 
  like 
  veritable 
  fairy 
  grottos. 
  I 
  have 
  never 
  

   found 
  geodes 
  in 
  any 
  other 
  locality, 
  but 
  here 
  they 
  are 
  extremely 
  

   abundant. 
  

  

  Volcanoes 
  are 
  also 
  recorded 
  as 
  existing 
  on 
  the 
  south-east 
  and 
  on 
  

   the 
  north-west 
  coast; 
  but 
  of 
  these 
  nothing 
  more 
  seems 
  to 
  be 
  at 
  

   present 
  known 
  than 
  the 
  bare 
  fact 
  of 
  their 
  existence. 
  Basaltic 
  pro- 
  

   trusions, 
  dykes, 
  and 
  sheets 
  also 
  occur 
  in 
  numerous 
  localities 
  through- 
  

   out 
  the 
  island, 
  bearing 
  witness 
  to 
  the 
  intense 
  volcanic 
  energy 
  that 
  

   has 
  prevailed 
  at 
  a 
  remote 
  period 
  in 
  this 
  part 
  of 
  the 
  world. 
  

  

  Prom 
  what 
  has 
  been 
  said 
  respecting 
  the 
  volcanoes 
  of 
  Madagascar 
  

   it 
  will 
  be 
  seen 
  that 
  they 
  run 
  in 
  a 
  direction 
  more 
  or 
  less 
  parallel 
  

   to 
  the 
  dominant 
  strike 
  of 
  the 
  rocks, 
  that 
  is 
  to 
  say, 
  from 
  north 
  to 
  

   south, 
  and 
  hence 
  are 
  part 
  of 
  the 
  chain 
  of 
  volcanoes 
  which 
  passes 
  

   along 
  the 
  line 
  of 
  the 
  lied 
  Sea 
  and 
  the 
  eastern 
  coast 
  of 
  Africa, 
  and 
  

   which 
  Prof. 
  Judd 
  would 
  include 
  in 
  his 
  " 
  fourth 
  and 
  subordinate 
  

   band." 
  

  

  Thermal 
  Springs 
  &c. 
  

  

  Besides 
  the 
  volcanic 
  phenomena 
  mentioned 
  above, 
  thermal 
  springs 
  

   occur 
  in 
  various 
  localities 
  in 
  Madagascar. 
  They 
  are 
  found 
  to 
  the 
  

   west 
  of 
  Valalafotsy 
  (east 
  of 
  Imerimandroso) 
  ; 
  at 
  a 
  place 
  in 
  the 
  bed 
  

   of 
  the 
  river 
  Ikopa, 
  about 
  45 
  or 
  50 
  miles 
  north-west 
  of 
  the 
  capital 
  

   (at 
  the 
  south 
  end 
  of 
  the 
  hill 
  of 
  Ankadivato 
  in 
  Valalafotsy) 
  ; 
  also 
  

   at 
  a 
  place 
  a 
  few 
  miles 
  further 
  down 
  the 
  river 
  ; 
  at 
  the 
  south-east 
  

   corner 
  of 
  Ifanja 
  marsh 
  ; 
  a 
  few 
  miles 
  to 
  the 
  south-west 
  of 
  Mahatsinjo 
  

   (south-west 
  of 
  Itasy) 
  ; 
  at 
  Andranomafana 
  (at 
  the 
  north-west 
  [?] 
  foot 
  

   of 
  Vavavato 
  mountain) 
  ; 
  at 
  Paravato 
  (to 
  the 
  south-west 
  of 
  Vavavato) 
  

   in 
  the 
  Betafo 
  valley, 
  -where 
  at 
  one 
  place 
  the 
  hot 
  water 
  pours 
  out 
  in 
  

   great 
  quantity 
  and 
  at 
  a 
  temperature 
  of 
  130° 
  Fahr. 
  

  

  These 
  seven 
  thermal 
  springs 
  lie 
  in 
  a 
  northerly 
  and 
  southerly 
  di- 
  

   rection, 
  extending 
  for 
  about 
  a 
  hundred 
  miles, 
  and 
  corresponding 
  

   with 
  the 
  line 
  of 
  the 
  Mandridrano 
  and 
  Betafo 
  volcanoes 
  (about 
  long. 
  

   47°). 
  They 
  probably 
  point 
  to 
  a 
  line 
  of 
  fissure. 
  

  

  M. 
  Roblet 
  reports 
  hot 
  springs 
  as 
  occurring 
  on 
  the 
  banks 
  of 
  the 
  

   river 
  Sahasarotra, 
  fifteen 
  miles 
  from 
  Vinaninony. 
  At 
  Antsirabe, 
  

   about 
  seventy 
  miles 
  south-west 
  of 
  Antananarivo, 
  there 
  is 
  a 
  hot 
  

   spring, 
  and 
  from 
  several 
  points 
  carbonic 
  acid 
  gas 
  is 
  emitted. 
  

   Another 
  spring 
  exists 
  at 
  Andranomafana 
  (east 
  of 
  Andovoranto) 
  near 
  

   the 
  east 
  coast. 
  The 
  Rev. 
  W. 
  D. 
  Cowan 
  also 
  gives 
  the 
  following 
  

   positions 
  where 
  hot 
  springs 
  occur 
  : 
  — 
  East 
  base 
  of 
  hills 
  near 
  River 
  

   Inamorona 
  (47° 
  38' 
  E. 
  by 
  21° 
  10' 
  S.) 
  ; 
  north 
  of 
  River 
  Matsiatra 
  

   near 
  Ivohibola 
  (47° 
  18' 
  E. 
  by 
  21 
  c 
  16' 
  S.). 
  It 
  is 
  reported 
  that 
  

   there 
  is 
  a 
  spring 
  of 
  mineral 
  oil 
  somewhere 
  to 
  the 
  north 
  of 
  Betafo 
  ; 
  

   and 
  the 
  Prench, 
  it 
  is 
  said, 
  have 
  worked 
  similar 
  springs 
  at 
  Ambava- 
  

  

  