﻿FISSURES 
  AND 
  VENTS. 
  gi 
  

  

  these 
  same 
  peculiarities 
  would 
  encourage 
  the 
  formation 
  of 
  fissures 
  

   in 
  the 
  same 
  direction 
  as 
  the 
  crest 
  of 
  the 
  waves, 
  or 
  at 
  right 
  angles 
  

   to 
  it, 
  rather 
  than 
  in 
  any 
  other 
  direction. 
  

  

  In 
  his 
  official 
  report 
  on 
  the 
  earthquake 
  in 
  Kuch 
  Bihar, 
  Mr. 
  

   D. 
  R. 
  Lyall, 
  C. 
  S. 
  I., 
  Superintendent 
  of 
  State, 
  remarks 
  that 
  where 
  the 
  

   soil 
  is 
  sandy 
  the 
  usual 
  form 
  of 
  fissure 
  was 
  a 
  simple 
  opening 
  of 
  the 
  

   soil, 
  but 
  in 
  the 
  racecourse 
  at 
  Kuch 
  Bihar, 
  where 
  the 
  soil 
  is 
  more 
  

   clayey, 
  there 
  was 
  generally 
  a 
  double 
  fissure, 
  the 
  soil 
  between 
  which 
  

   sank 
  from 
  a 
  foot 
  to 
  eighteen 
  inches, 
  and, 
  as 
  a 
  rule, 
  no 
  sand 
  issued. 
  

   Near 
  Maimansingh 
  Mr. 
  Grimes 
  noticed 
  the 
  same 
  feature, 
  where 
  

   fissures 
  ran 
  on 
  either 
  side 
  of 
  the 
  road, 
  and 
  throughout 
  the 
  area 
  

   affected 
  by 
  fissuring, 
  it 
  is 
  common 
  to 
  find 
  two 
  parallel 
  fissures 
  bound- 
  

   ing 
  a 
  strip 
  of 
  sunken 
  land. 
  

  

  Where 
  the 
  fissures 
  penetrate 
  down 
  to 
  a 
  bed 
  of 
  sand 
  or 
  slime, 
  

   part 
  of 
  which 
  has 
  been 
  forced 
  out 
  through 
  the 
  fissures, 
  it 
  is 
  

   easy 
  enough 
  to 
  account 
  for 
  this 
  subsidence, 
  but 
  it 
  may 
  also 
  

   take 
  place 
  where 
  no 
  material 
  has 
  been 
  forced 
  out 
  from 
  below. 
  

   Suppose 
  two 
  parallel, 
  or 
  nearly 
  parallel 
  fissures 
  starting 
  from 
  the 
  

   surface 
  and 
  gradually 
  approaching 
  each 
  other 
  underground 
  so 
  as 
  to 
  

   cut 
  off 
  a 
  wedge 
  shaped 
  piece 
  of 
  alluvium 
  as 
  shown 
  in 
  fig. 
  10, 
  then, 
  

   as 
  the 
  wave 
  reaches 
  such 
  a 
  position 
  that 
  we 
  have 
  opposite 
  semi- 
  

   phases 
  of 
  the 
  wave 
  on 
  either 
  side 
  of 
  this 
  pair 
  of 
  fissures 
  and 
  the 
  

   movement 
  of 
  the 
  wave 
  particles 
  away 
  from 
  the 
  fissures, 
  as 
  indicated 
  

   by 
  the 
  lower 
  pair 
  of 
  arrows 
  in 
  fig. 
  10, 
  there 
  will 
  be 
  an 
  opening 
  of 
  the 
  

  

  Fig. 
  10. 
  Diagram 
  to 
  illustrate 
  the 
  formation 
  of 
  fissures 
  in 
  alluvium. 
  

  

  fissures 
  and 
  the 
  wedge 
  will 
  drop 
  down. 
  As 
  the 
  wave 
  passes 
  on 
  the 
  

   action 
  is 
  reversed, 
  the 
  motion 
  of 
  wave 
  particles 
  in 
  both 
  semi- 
  

   phases 
  will 
  be 
  inwards 
  and 
  the 
  wedge 
  will 
  be 
  compresssed, 
  as 
  indicated 
  

  

  ( 
  9i 
  ) 
  

  

  