﻿*3 
  OLDHAM 
  : 
  GREAT 
  EARTHQUAKE 
  OF 
  1S97. 
  

  

  of 
  strength 
  is 
  to 
  be 
  found 
  in 
  the 
  buildings 
  being, 
  as 
  a 
  rule, 
  not 
  detach* 
  

   ed 
  but 
  built 
  in 
  rows, 
  and 
  where 
  this 
  was 
  the 
  case 
  it 
  was 
  seldom 
  that 
  

   any 
  but 
  the 
  end 
  houses 
  suffered, 
  except 
  in 
  the 
  case 
  of 
  those 
  which 
  

   were 
  old 
  and 
  badly 
  built. 
  

  

  In 
  accounts 
  of 
  great 
  earthquakes, 
  at 
  any 
  rate 
  those 
  written 
  in 
  

   modern 
  times, 
  it 
  is 
  usual 
  to 
  attempt 
  a 
  detailed 
  delineation 
  of 
  a 
  

   greater 
  or 
  less 
  number 
  of 
  isoseismal 
  lines, 
  and 
  much 
  information 
  can 
  

   doubtless 
  be 
  derived 
  from 
  the 
  evidence 
  their 
  irregularities 
  gives 
  of 
  

   the 
  irregular 
  distribution 
  of 
  the 
  energy 
  of 
  the 
  earthquake. 
  In 
  no 
  

   case 
  do 
  the 
  isoseists 
  have 
  that 
  regular 
  circular 
  or 
  elliptical 
  form 
  

   which 
  would 
  be 
  found 
  if 
  the 
  wave 
  was 
  propagated 
  through 
  a 
  homog- 
  

   eneous 
  medium, 
  but 
  in 
  the 
  case 
  of 
  the 
  present 
  earthquake 
  it 
  has 
  been 
  

   found 
  impossible 
  to 
  draw 
  these 
  irregularities 
  with 
  any 
  degree 
  of 
  

   accuracy, 
  and 
  the 
  isoseists 
  actually 
  drawn 
  on 
  map 
  No. 
  1 
  are 
  

   purely 
  diagramatic 
  and 
  represent 
  their 
  probable 
  course 
  if 
  we 
  

   could 
  suppose 
  local 
  conditions 
  everywhere 
  uniform, 
  and 
  the 
  diminu- 
  

   tion 
  of 
  the 
  violence 
  of 
  the 
  shock 
  comparable 
  to 
  that 
  which 
  can 
  be 
  

   recognised 
  in 
  a 
  westerly 
  direction 
  along 
  the 
  plains 
  of 
  Upper 
  India. 
  

  

  It 
  will 
  be 
  noticed 
  that 
  these 
  curves 
  come 
  closer 
  together 
  on 
  the 
  

   east 
  and 
  south-east 
  than 
  on 
  the 
  west 
  and 
  south-west, 
  and 
  I 
  believe 
  

   that 
  this 
  closing 
  in 
  is, 
  at 
  least 
  partly, 
  real, 
  and 
  not 
  due 
  to 
  imperfect 
  

   information. 
  On 
  the 
  north 
  nothing 
  is 
  known 
  of 
  the 
  course 
  of 
  the 
  

   isoseists, 
  and 
  it 
  is 
  not 
  impossible 
  that 
  the 
  closing 
  in 
  of 
  the 
  inner 
  

   isoseismic 
  lines 
  on 
  this 
  side 
  is 
  incorrect. 
  I 
  have 
  drawn 
  them 
  in 
  

   accordance 
  with 
  what 
  little 
  is 
  known 
  and 
  with 
  what 
  might 
  reason- 
  

   ably 
  be 
  expected, 
  but 
  no 
  value 
  can 
  be 
  attached 
  to 
  this 
  portion 
  of 
  

   the 
  curves. 
  

  

  So 
  sketchy 
  a 
  delineation 
  of 
  the 
  isoseismic 
  lines 
  may 
  be 
  regarded 
  

   as 
  unsatisfactory, 
  and 
  it 
  certainly 
  compares 
  unfavourably 
  with 
  the 
  

   elaborate 
  delineation 
  of 
  the 
  actual 
  courses 
  of 
  a 
  much 
  larger 
  number 
  

   of 
  lines 
  given 
  by 
  Captain 
  Dutton 
  in 
  his 
  account 
  of 
  the 
  Charles- 
  

   ton 
  Earthquake 
  of 
  1886. 
  The 
  difference 
  is 
  largely 
  inevitable 
  

   but 
  partly 
  deliberate. 
  At 
  a 
  very 
  early 
  stage 
  of 
  the 
  investigation 
  of 
  

  

  (48) 
  

  

  