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  GEOLOGY. 
  

  

  iron 
  bar, 
  or 
  sinker, 
  which 
  forms 
  the 
  iipj^er 
  section 
  of 
  the 
  

   rods, 
  and 
  is 
  provided 
  with 
  a 
  series 
  of 
  holes, 
  at 
  suitable 
  

   distances 
  along 
  its 
  entire 
  length, 
  about 
  ten 
  feet, 
  through 
  

   which 
  the 
  lever 
  is 
  keyed, 
  and 
  by 
  means 
  of 
  which 
  it 
  can 
  

   be 
  shifted 
  and 
  adjusted 
  at 
  a 
  higher 
  elevation, 
  as 
  the 
  

   auger 
  descends. 
  

  

  To 
  the 
  lower 
  end 
  of 
  the 
  sinker, 
  wooden 
  i^ods, 
  in 
  sec- 
  

   tions 
  of 
  about 
  twenty 
  feet 
  in 
  length, 
  tipped 
  with 
  iron 
  to 
  

   admit 
  of 
  being 
  screwed 
  together 
  as 
  the 
  work 
  progresses, 
  

   are 
  attached 
  ; 
  and 
  these 
  are 
  elevated, 
  as 
  occasion 
  re- 
  

   quires, 
  by 
  the 
  rope 
  by 
  which 
  they 
  are 
  suspended, 
  passing 
  

   through 
  the 
  block, 
  and 
  connecting 
  with 
  a 
  windlass, 
  

   which 
  may 
  be 
  worked, 
  if 
  necessary, 
  by 
  horse-power. 
  

  

  A 
  bored 
  log 
  is 
  usually 
  inserted 
  down 
  to 
  the 
  indurated 
  

   marl 
  or 
  lime-rock. 
  This 
  is 
  necessary 
  to 
  prevent 
  the 
  

   loose 
  incoherent 
  earth 
  or 
  sand 
  of 
  the 
  upper 
  strata 
  from 
  

   caving 
  in 
  or 
  being 
  washed 
  away. 
  The 
  log 
  has 
  an 
  aperture 
  

   sufficient 
  to 
  admit 
  the 
  free 
  passage 
  of 
  the 
  auger 
  and 
  

   rods, 
  and 
  is 
  driven 
  or 
  forced 
  down 
  in 
  one 
  or 
  more 
  sec- 
  

   tions 
  of 
  twenty 
  feet, 
  suitably 
  united, 
  to 
  the 
  requisite 
  

   depth, 
  which 
  is 
  sometimes 
  near 
  a 
  hundred 
  feet. 
  

  

  When 
  the 
  compact 
  rock 
  is 
  penetrated, 
  and 
  sandy, 
  in- 
  

   coherent 
  strata 
  met 
  with, 
  tubing 
  becomes 
  necessary; 
  

   sheet-iron 
  is 
  generally 
  used 
  for 
  the 
  purpose, 
  but 
  cast-iron 
  

   pipes 
  are 
  considered 
  more 
  suitable. 
  

  

  Thirty 
  feet 
  a 
  day 
  can 
  be 
  bored 
  in 
  the 
  soft 
  lime 
  rock, 
  

   but 
  not 
  more 
  than 
  ten 
  in 
  the 
  sand-rock 
  or 
  green-sand. 
  

   Fifty 
  feet 
  is 
  sometimes 
  accomplished 
  the 
  first 
  day. 
  

  

  The 
  ordinary 
  charge 
  for 
  boring 
  is 
  thirty-three 
  cents 
  

   per 
  foot 
  for 
  the 
  first 
  three 
  hundred 
  feet 
  ; 
  for 
  the 
  next 
  

   two 
  hundred 
  feet, 
  fifty 
  cents; 
  and 
  over 
  five 
  hundred 
  

   feet, 
  one 
  dollar 
  per 
  foot. 
  

  

  The 
  tubing 
  with 
  sheet-iron, 
  is 
  estimated 
  to 
  cost 
  fifty 
  

   cents 
  per 
  foot. 
  

  

  