﻿72 
  OLDHAM: 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  The 
  third 
  group 
  of 
  observations, 
  those 
  from 
  Burma, 
  have 
  not 
  been 
  

   utilised 
  for 
  reasons 
  given 
  on 
  page 
  68. 
  

  

  Turning 
  to 
  Plate 
  XXXIX, 
  we 
  see 
  that 
  the 
  observations 
  show 
  a 
  

   fairly 
  regular 
  relation 
  between 
  the 
  time 
  of 
  commencement 
  and 
  dis- 
  

   tance 
  from 
  the 
  epicentre. 
  These 
  records 
  fall 
  so 
  well 
  together 
  that 
  it 
  

   is 
  possible 
  to 
  draw 
  a 
  line 
  through 
  them, 
  which 
  represents 
  the 
  rate 
  

   of 
  progression 
  of 
  the 
  earthquake, 
  and 
  from 
  which 
  we 
  can 
  deduce 
  the 
  

   rate 
  of 
  travel 
  at 
  any 
  point 
  with 
  greater 
  accuracy 
  than 
  is 
  possible 
  

   by 
  direct 
  calculation 
  from 
  the 
  times 
  recorded. 
  

  

  Two 
  such 
  lines 
  are 
  in 
  fact 
  drawn 
  on 
  the 
  plate. 
  Of 
  these 
  the 
  one 
  

   drawn 
  firm 
  is 
  that 
  which 
  most 
  closely 
  passes 
  through 
  the 
  centre 
  of 
  

   the 
  constellation 
  of 
  time 
  observations, 
  and 
  represents 
  the 
  probable 
  

   true 
  curve 
  of 
  the 
  times 
  of 
  arrival 
  of 
  the 
  shock 
  at 
  different 
  places 
  ; 
  

   the 
  other, 
  drawn 
  as 
  a 
  dotted 
  line, 
  is 
  that 
  which, 
  for 
  reasons 
  that 
  will 
  

   appear 
  in 
  the 
  sequel, 
  is 
  theoretically 
  more 
  probably 
  correct, 
  though 
  

   not 
  so 
  closely 
  in 
  accordance 
  with 
  the 
  recorded 
  observations, 
  In 
  either 
  

   case 
  the 
  meaning 
  of 
  the 
  line 
  is 
  that, 
  taking 
  any 
  point 
  on 
  the 
  

   line, 
  a 
  place 
  at 
  the 
  distance 
  from 
  the 
  origin 
  indicated 
  by 
  the 
  scale 
  of 
  

   miles 
  at 
  the 
  bottom 
  would 
  have 
  felt 
  the 
  earthquake 
  commence 
  at 
  

   the 
  time 
  indicated 
  by 
  the 
  scale 
  of 
  minutes 
  at 
  the 
  right 
  hand 
  end 
  

   of 
  the 
  diagram. 
  Taking 
  first 
  the 
  gently 
  curved 
  firm 
  line, 
  and 
  tabu- 
  

   lating 
  the 
  results 
  obtained 
  from 
  this 
  we 
  find 
  that, 
  taking 
  i6h. 
  26m* 
  

   as 
  the 
  time 
  at 
  which 
  the 
  earthquake 
  wave 
  first 
  reached 
  the 
  surface 
  

   and 
  started 
  on 
  its 
  outward 
  course, 
  the 
  distance 
  travelled 
  in 
  — 
  

  

  1 
  minute 
  was 
  ......... 
  170 
  miles. 
  

  

  2 
  minutes 
  ,, 
  280 
  „ 
  

  

  3 
  » 
  » 
  • 
  35o 
  „ 
  

  

  4 
  j> 
  »j 
  460 
  „ 
  

  

  5 
  »j 
  >> 
  580 
  ,, 
  

  

  6 
  »» 
  7oo 
  „ 
  

  

  7 
  » 
  >> 
  ....•...« 
  840 
  ,, 
  

  

  8 
  »> 
  » 
  9go 
  ,, 
  

  

  9 
  » 
  w 
  1,150 
  „ 
  

  

  Or, 
  in 
  other 
  words, 
  the 
  distance 
  travelled 
  in 
  the 
  — 
  

  

  1 
  st 
  minute 
  was 
  170 
  miles. 
  

  

  2nd 
  „ 
  „ 
  . 
  no 
  „ 
  

  

  3rd 
  „ 
  „ 
  80 
  „ 
  

  

  4th 
  „ 
  „ 
  . 
  . 
  t 
  110 
  „ 
  

  

  (72 
  ) 
  

  

  