﻿THE 
  EPICENTRAL 
  TRACT. 
  133 
  

  

  The 
  upper 
  limit 
  of 
  size 
  is 
  due 
  to 
  another 
  cause. 
  The 
  motion 
  of 
  

   the 
  earthquake 
  wave 
  has 
  to 
  be 
  communicated 
  to 
  the 
  stone 
  through 
  

   the, 
  comparatively, 
  yielding 
  and 
  inelastic 
  soil, 
  in 
  which 
  it 
  is 
  partially 
  

   imbedded. 
  But 
  the 
  stone 
  does 
  not 
  take 
  up 
  the 
  motion 
  immediately 
  

   or 
  without 
  some 
  resistance 
  from 
  its 
  own 
  inertia, 
  which 
  increases 
  

   with 
  the 
  mass 
  of 
  the 
  stone, 
  and 
  part 
  of 
  the 
  energy 
  of 
  the 
  shock 
  is 
  

   consequently 
  taken 
  up 
  in 
  compressing 
  the 
  soil 
  under 
  the 
  stone. 
  In 
  the 
  

   case 
  of 
  smaller 
  fragments 
  this 
  proportion 
  may 
  be 
  small, 
  the 
  stone 
  

   quickly 
  takes 
  up 
  the 
  movement 
  of 
  the 
  earthquake 
  wave, 
  and 
  the 
  

   velocity 
  communicated 
  to 
  it 
  may 
  be 
  not 
  much 
  less 
  than 
  that 
  of 
  the 
  

   wave 
  particle 
  in 
  the 
  rock 
  below 
  the 
  layer 
  of 
  soil. 
  The 
  larger 
  the 
  

   mass 
  of 
  the 
  stone, 
  however, 
  the 
  slower 
  it 
  takes 
  up 
  the 
  motion 
  of 
  the 
  

   wave 
  and 
  the 
  greater 
  the 
  work 
  expended 
  in 
  compressing 
  the 
  yield- 
  

   ing 
  soil 
  beneath 
  it 
  ; 
  after 
  this 
  deduction, 
  the 
  velocity 
  of 
  movement 
  

   actually 
  imparted 
  to 
  the 
  stone 
  may 
  be 
  insufficient 
  to 
  enable 
  it 
  to 
  

   leave 
  its 
  bed 
  and 
  travel 
  as 
  a 
  projectile 
  through 
  the 
  air. 
  

  

  This 
  upper 
  limit 
  was 
  about 
  3 
  ft. 
  in 
  diameter, 
  the 
  fragments 
  being 
  

   generally 
  of 
  a 
  rudely 
  spheroidal 
  form. 
  Larger 
  rocks 
  were 
  displaced 
  in 
  

   abundance, 
  dislodged 
  from 
  their 
  sites, 
  and 
  caused 
  to 
  roll 
  down 
  the 
  hill- 
  

   sides, 
  but 
  I 
  saw 
  very 
  few 
  cases 
  of 
  stones 
  as 
  large 
  as 
  3 
  ft. 
  in 
  diameter 
  

   which 
  had 
  been 
  actually 
  projected 
  in 
  a 
  free 
  course 
  through 
  the 
  air. 
  

  

  Both 
  at 
  Goalpara 
  and 
  Gauhati 
  instances 
  of 
  objects 
  projected 
  

   through 
  the 
  air 
  were 
  observed, 
  and 
  at 
  the 
  latter 
  place 
  there 
  is 
  inde- 
  

   pendent 
  evidence 
  of 
  a 
  high 
  angle 
  of 
  emergence. 
  In 
  the 
  centre 
  of 
  

   the 
  river, 
  opposite 
  Gauhati, 
  rises 
  a 
  small 
  island, 
  commonly 
  known 
  

   as 
  Peacock 
  Island, 
  which 
  is 
  regarded 
  as 
  sacred, 
  and 
  crowned 
  with 
  an 
  

   ancient 
  temple. 
  It 
  is 
  stated 
  that 
  before 
  the 
  shock 
  of 
  1897, 
  though 
  

   earthquakes 
  had 
  visited 
  and 
  damaged 
  both 
  banks 
  of 
  the 
  river, 
  they 
  

   had 
  never 
  been 
  able 
  to 
  reach 
  this 
  island, 
  an 
  immunity 
  which 
  was 
  

   attributed 
  to 
  its 
  sanctity, 
  but 
  finds 
  a 
  rational 
  explanation 
  in 
  the 
  deep 
  

   channel 
  of 
  the 
  Brahmaputra 
  which 
  surrounds 
  it. 
  

  

  The 
  investigations 
  in 
  Japan 
  1 
  have 
  shown 
  how 
  completely 
  the 
  

  

  1 
  J. 
  Milne 
  : 
  Trans. 
  Seismol. 
  Soc, 
  Japan, 
  VIII, 
  98; 
  S. 
  Sekiya 
  and 
  F. 
  Omori, 
  Jour. 
  ColL 
  

   Sci, 
  Imp. 
  Univ. 
  Japan, 
  IV, 
  Pt. 
  ii, 
  249 
  (1891). 
  

  

  ( 
  133 
  ) 
  

  

  