﻿246 
  

  

  OLDHAM 
  : 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  I 
  

  

  2 
  

  

  3 
  

  

  4 
  

  

  5 
  

  

  6 
  

  

  7 
  

  

  

  Latitude. 
  

  

  Longitude. 
  

  

  Angle. 
  

  

  Arc. 
  

  

  Chord. 
  

  

  Versin. 
  

  

  Potsdam 
  . 
  

  

  

  1 
  • 
  

  

  52°2 
  5 
  / 
  N 
  

  

  i 
  3 
  °2'E 
  

  

  62*36' 
  

  

  4,322 
  

  

  4,111 
  

  

  576 
  

  

  Ischia 
  

  

  

  • 
  

  

  4o°45' 
  N 
  

  

  i3°58' 
  E 
  

  

  63°28' 
  

  

  '4,382 
  

  

  4,162 
  

  

  591 
  

  

  Catania 
  . 
  

  

  

  • 
  

  

  37°28' 
  N 
  

  

  i3°28' 
  E 
  

  

  63°53' 
  

  

  4,411 
  

  

  4,185 
  

  

  599 
  

  

  Rome 
  . 
  

  

  

  

  4i°54' 
  N 
  

  

  1 
  i°28' 
  E 
  

  

  64° 
  5' 
  

  

  4,425 
  

  

  4,198 
  

  

  603 
  

  

  Padua 
  • 
  

  

  

  . 
  

  

  45°24' 
  N 
  

  

  ii°5o'E 
  

  

  64°2 
  9 
  ' 
  

  

  4,452 
  

  

  4,221 
  

  

  610 
  

  

  Siena 
  

  

  

  - 
  

  

  43°i9' 
  N 
  

  

  n°i9'E 
  

  

  6?i8' 
  

  

  4,5o9 
  

  

  4,269 
  

  

  625 
  

  

  Pavia 
  

  

  

  . 
  

  

  45°n' 
  N 
  

  

  9°io' 
  E 
  

  

  66°22' 
  

  

  4,582 
  

  

  4,331 
  

  

  645 
  

  

  Strassburg 
  

  

  

  . 
  

  

  48°35' 
  N 
  

  

  7°43' 
  E 
  

  

  66°32' 
  

  

  4,594 
  

  

  4,34o 
  

  

  648 
  

  

  Grenoble 
  

  

  

  • 
  

  

  45°«o' 
  N 
  

  

  5>'E 
  

  

  68°i4' 
  

  

  4,7" 
  

  

  4,438 
  

  

  68 
  1 
  

  

  Edinburgh 
  

  

  

  • 
  

  

  55°57' 
  N 
  

  

  3° 
  i'W 
  

  

  7o°5i' 
  

  

  4,891 
  

  

  4,586 
  

  

  732 
  

  

  bnide 
  

  

  

  • 
  

  

  5o°4i' 
  N 
  

  

  i°i9'W 
  

  

  7i°34' 
  

  

  4,942 
  

  

  4,626 
  

  

  747 
  

  

  In 
  this 
  table 
  the 
  first 
  three 
  columns 
  require 
  no 
  explanation. 
  The 
  

   fourth 
  column 
  represents 
  the 
  angle 
  subtended, 
  at 
  the 
  centre 
  of 
  the 
  

   earth 
  by 
  the 
  place 
  mentioned 
  in 
  the 
  first 
  column, 
  and 
  an 
  assumed 
  

   centre 
  in 
  N. 
  Lat. 
  25°45', 
  E, 
  Long. 
  91*0 
  '. 
  The 
  fifth 
  column 
  is 
  the 
  

   length 
  of 
  the 
  corresponding 
  arc 
  in 
  miles, 
  calculated 
  to 
  a 
  mean 
  

   radius 
  of 
  3,956 
  statute 
  miles 
  ; 
  or, 
  in 
  other 
  words, 
  the 
  distance 
  in 
  a 
  

   direct 
  line, 
  measured 
  along 
  the 
  surface 
  of 
  the 
  earth. 
  Column 
  6 
  gives 
  

   the 
  distance 
  in 
  a 
  direct 
  line 
  measured 
  through 
  the 
  earth, 
  and 
  

   column 
  7 
  the 
  greatest 
  depth, 
  in 
  miles, 
  of 
  this 
  line 
  from 
  the 
  surface. 
  

   In 
  calculating 
  6 
  and 
  7, 
  the 
  focus 
  was 
  assumed 
  to 
  be 
  at 
  the 
  surface, 
  

   and 
  they 
  are 
  consequently 
  subject 
  to 
  an 
  inaccuracy 
  on 
  this 
  account, 
  

   which 
  would 
  tend 
  to 
  increase 
  the 
  value 
  of 
  6 
  and 
  diminish 
  that 
  of 
  7. 
  

   In 
  other 
  words, 
  the 
  true 
  distance 
  in 
  a 
  direct 
  line 
  would 
  be 
  rather 
  less 
  

   than 
  that 
  tabulated, 
  and 
  the 
  true 
  depth 
  rather 
  greater. 
  The 
  error 
  

   is, 
  however, 
  proportionately 
  so 
  small 
  that 
  it 
  may 
  be 
  neglected. 
  

  

  Taking 
  these 
  distances, 
  we 
  may 
  calculate 
  the 
  rates 
  of 
  travel, 
  

   represented 
  by 
  the 
  principal 
  epochs 
  in 
  the 
  records. 
  In 
  doing 
  so, 
  we 
  

   may 
  assume 
  that 
  all 
  the 
  waves 
  started 
  at 
  the 
  same 
  time 
  from 
  the 
  

   ( 
  246 
  ) 
  

  

  