﻿THE 
  EARTHQUAKE 
  SOUND. 
  199 
  

  

  Were 
  this 
  the 
  case, 
  we 
  should 
  expect 
  that 
  the 
  sound 
  would 
  

   beat 
  its 
  loudest 
  shortly 
  after 
  its 
  commencement 
  and 
  gradually 
  die 
  

   away. 
  To 
  a 
  certain 
  extent 
  this 
  is 
  the 
  case, 
  but 
  the 
  final 
  dying 
  out 
  

   of 
  the 
  sound 
  is 
  usually 
  so 
  short 
  in 
  comparison 
  to 
  its 
  total 
  duration, 
  

   that, 
  if 
  explicable 
  in 
  this 
  way, 
  the 
  real 
  duration 
  of 
  the 
  sound 
  waves 
  

   in 
  the 
  ground 
  must 
  be 
  within 
  a 
  few 
  seconds 
  of 
  the 
  apparent 
  duration 
  

   of 
  the 
  sound. 
  

  

  Another 
  objection 
  to 
  the 
  idea 
  that 
  the 
  prolonged 
  duration 
  of 
  the 
  

   sounds 
  is 
  due 
  to 
  its 
  gradual 
  arrival, 
  through 
  the 
  air, 
  from 
  more 
  and 
  

   more 
  distant 
  origins, 
  is 
  its 
  lovvness, 
  the 
  word 
  being 
  here 
  used 
  with 
  

   regard 
  to 
  the 
  volume, 
  not 
  the 
  pitch 
  of 
  the 
  sound. 
  Quite 
  nine-tenths 
  

   of 
  the 
  sounds 
  I 
  heard 
  were 
  never 
  loud 
  enough 
  to 
  travel 
  even 
  half 
  a 
  

   mile, 
  about 
  as 
  far 
  as 
  they 
  could 
  travel 
  in 
  2\ 
  seconds, 
  and 
  remain 
  

   audible. 
  Hence 
  it 
  is 
  evident 
  that 
  durations 
  of 
  10 
  or 
  20 
  seconds 
  

   cannot 
  be 
  explained, 
  as 
  in 
  the 
  case 
  of 
  a 
  prolonged 
  thunderclap, 
  by 
  

   the 
  varying 
  distances 
  that 
  the 
  sound 
  has 
  travelled 
  through 
  the 
  air. 
  

  

  As 
  another 
  argument 
  leading 
  to 
  the 
  same 
  conclusion, 
  it 
  may 
  be 
  

   said 
  that 
  the 
  sounds 
  appeared 
  to 
  be 
  much 
  more 
  noticeable 
  indoors 
  

   than 
  out 
  of 
  doors. 
  On 
  the 
  hypothesis 
  of 
  local 
  origin 
  this 
  is 
  easily 
  

   understood, 
  for 
  not 
  only 
  would 
  the 
  walls 
  and 
  ceiling 
  of 
  a 
  room 
  serve 
  

   to 
  confine, 
  and 
  so 
  intensify, 
  the 
  sound, 
  but 
  they 
  would 
  themselves 
  

   be 
  set 
  in 
  vibration 
  and 
  communicate 
  these 
  vibrations 
  to 
  the 
  air 
  of 
  

   the 
  room. 
  It 
  even 
  seemed 
  to 
  me 
  that 
  the 
  sounds 
  were 
  noticeably 
  

   more 
  audible 
  in 
  a 
  tent 
  than 
  in 
  the 
  open; 
  here 
  the 
  tent 
  walls 
  could 
  

   not 
  communicate 
  sound-waves 
  to 
  the 
  air, 
  but 
  they 
  would 
  serve 
  to 
  con- 
  

   centrate 
  those 
  communicated 
  by 
  the 
  ground. 
  

  

  From 
  its 
  very 
  nature 
  this 
  last 
  argument 
  is 
  based 
  on 
  an 
  impression 
  

   which 
  is 
  incapable 
  of 
  proof, 
  as 
  it 
  is 
  impossible 
  for 
  the 
  same 
  observer 
  

   to 
  be 
  both 
  in 
  and 
  out 
  of 
  doors 
  at 
  the 
  same 
  moment. 
  The 
  number 
  of 
  

   earthquake 
  sounds 
  heard 
  during 
  the 
  fci 
  r 
  m 
  >nths 
  I 
  was 
  in 
  Assam 
  

   was, 
  however, 
  so 
  great 
  that 
  a 
  certain 
  amount 
  of 
  comparison 
  was 
  pos- 
  

   sible 
  ; 
  it 
  was 
  moreover 
  a 
  point 
  to 
  which 
  I 
  paid 
  special 
  attention 
  and 
  I 
  

   believe 
  that 
  the 
  statement 
  in 
  the 
  last 
  paragraph 
  represents 
  a 
  real 
  fact. 
  

  

  The 
  general 
  conclusion 
  come 
  to 
  as 
  the 
  result 
  of 
  observations 
  

  

  ( 
  199 
  ) 
  

  

  