﻿260 
  GEOLOGY. 
  

  

  springs 
  of 
  Madison, 
  Marion, 
  and 
  Pike 
  Counties; 
  a 
  white 
  

   sulphur 
  spring 
  in 
  Neshoba 
  County; 
  and 
  the 
  springs 
  in 
  

   Marshall 
  and 
  Lafayette, 
  the 
  properties 
  of 
  which 
  I 
  have 
  

   not 
  learned. 
  

  

  ARTESIAN 
  WELLS. 
  

  

  Artesian 
  wells, 
  so 
  called 
  from 
  the 
  province 
  of 
  Artois, 
  

   in 
  France, 
  where 
  they 
  are 
  generally 
  supposed 
  to 
  have 
  

   been 
  first 
  constructed, 
  are 
  of 
  such 
  a 
  description, 
  that, 
  by 
  

   boring 
  into 
  the 
  earth 
  to 
  the 
  requisite 
  depth, 
  water 
  is 
  

   obtained 
  on 
  the 
  surface 
  or 
  escapes 
  from 
  the 
  orifice 
  in 
  a 
  

   jet 
  to 
  a 
  variable 
  height 
  above 
  it, 
  and 
  this 
  result 
  is 
  due 
  to 
  

   the 
  principle 
  that 
  water 
  will 
  find 
  its 
  own 
  level. 
  

  

  Success, 
  therefore, 
  is 
  not 
  to 
  be 
  expected 
  alike 
  in 
  all 
  

   situations, 
  and 
  such 
  borings 
  are 
  to 
  be 
  undertaken 
  only 
  

   in 
  those 
  formations, 
  or 
  under 
  certain 
  conditions 
  of 
  geolo- 
  

   gical 
  structure, 
  in 
  which 
  the 
  strata 
  are 
  so 
  disposed 
  in 
  

   reference 
  to 
  their 
  dip 
  or 
  inclination, 
  and 
  their 
  character 
  

   and 
  consistency, 
  as 
  to 
  render 
  this 
  practicable. 
  

  

  Plate 
  XI., 
  Fig. 
  2, 
  exhibits 
  a 
  section 
  of 
  such 
  a 
  stratifi- 
  

   cation 
  as 
  answers 
  these 
  conditions. 
  

  

  The 
  whole 
  series 
  is 
  seen 
  so 
  curved 
  or 
  inclined 
  by 
  some 
  

   subterranean 
  movement 
  as 
  to 
  present 
  a 
  concave 
  surface 
  

   or 
  basin-shaped 
  structure: 
  A 
  represents 
  a 
  stratum 
  of 
  

   such 
  consistency 
  or 
  character 
  of 
  rock 
  as 
  to 
  retain 
  the 
  

   water 
  falling 
  on 
  it, 
  upon 
  its 
  surface 
  ; 
  B 
  a 
  stratum 
  of 
  sand 
  

   and 
  gravel, 
  or 
  of 
  such 
  other 
  porous 
  materials 
  as 
  will 
  

   absorb 
  the 
  water 
  w^hich 
  fiills 
  upon 
  and 
  is 
  conducted 
  into 
  

   it 
  by 
  Af 
  and 
  which 
  is 
  prevented 
  from 
  rising 
  above 
  by 
  

   the 
  retentive 
  strata 
  of 
  clay, 
  or 
  any 
  impervious 
  rock, 
  

   represented 
  by 
  C. 
  Borings 
  from 
  the 
  surface, 
  as 
  at 
  E 
  

   E, 
  penetrating 
  into 
  the 
  water-bearing 
  stratum 
  B, 
  will 
  

  

  