﻿THE 
  UNFELT 
  EARTHQUAKE. 
  

  

  247 
  

  

  centre, 
  and 
  as 
  a 
  matter 
  of 
  fact 
  they 
  certainly 
  did 
  so 
  within 
  a 
  minute 
  

   of 
  time. 
  

  

  Taking 
  the 
  time 
  of 
  arrival 
  of 
  the 
  first 
  tremors, 
  we 
  have 
  the 
  follow- 
  

   ing 
  result: 
  — 
  

  

  

  Interval 
  in 
  

   minutes. 
  

  

  APPARENT 
  RATE 
  OF 
  TRAVEL 
  ALONG 
  

  

  

  Surface. 
  

  

  Direct 
  line. 
  

  

  

  Miles 
  per 
  

   min. 
  

  

  Kilometres 
  

   per 
  sec. 
  

  

  Miles 
  per 
  

   min. 
  

  

  Kilometres 
  

   per 
  sec. 
  

  

  Ischia 
  .... 
  

  

  12-25 
  

  

  366 
  

  

  9*68 
  

  

  34o 
  

  

  8-99 
  

  

  Catania 
  . 
  . 
  I 
  . 
  

  

  12-5 
  

  

  353 
  

  

  9*33 
  

  

  335 
  

  

  8-86 
  

  

  Rome, 
  Rocca 
  di 
  Papa 
  

  

  1275 
  

  

  347 
  

  

  9'i8 
  

  

  329 
  

  

  871 
  

  

  „ 
  Ufficio 
  centrale 
  

  

  10*0 
  

  

  3^9 
  

  

  975 
  

  

  35o 
  

  

  9*25 
  

  

  Padua 
  • 
  

  

  ii75 
  

  

  379 
  

  

  IO*02 
  

  

  359 
  

  

  9'5<> 
  

  

  Siena 
  .... 
  

  

  I2'o 
  

  

  376 
  

  

  9*94 
  

  

  356 
  

  

  9-41 
  

  

  Pavia 
  .... 
  

  

  13*25 
  

  

  355 
  

  

  9'I9 
  

  

  347 
  

  

  8-64 
  

  

  Arithmetical 
  mean 
  . 
  

  

  I2"36 
  

  

  364 
  

  

  9*58 
  

  

  345 
  

  

  9*05 
  

  

  Potsdam 
  .... 
  

  

  1375 
  

  

  3»4 
  

  

  8*32 
  

  

  299 
  

  

  7'9i 
  

  

  Strassburg 
  . 
  . 
  

  

  13*5 
  

  

  34o 
  

  

  9*oo 
  

  

  321 
  

  

  8*50 
  

  

  Grenoble. 
  . 
  . 
  , 
  

  

  I40 
  

  

  33<5 
  

  

  8-90 
  

  

  317 
  

  

  8'39 
  

  

  Edinburgh 
  . 
  . 
  . 
  

  

  13-0 
  

  

  353 
  

  

  9*33 
  

  

  36i 
  

  

  9*95 
  

  

  That 
  is 
  to 
  say, 
  these 
  tremors 
  travelled 
  between 
  India 
  and 
  Europe 
  

   at 
  a 
  rate 
  of 
  about 
  345 
  miles 
  a 
  minute, 
  or 
  9*0 
  kilometres 
  a 
  second, 
  if 
  

   they 
  travelled 
  in 
  a 
  straight 
  line 
  from 
  point 
  to 
  point, 
  and 
  at 
  a 
  greater 
  

   rate 
  if 
  they 
  followed 
  a 
  curved 
  line. 
  

  

  Turning 
  to 
  the 
  time 
  of 
  commencement 
  of 
  the 
  second 
  phase 
  we 
  

   have 
  the 
  following 
  results 
  :— 
  

  

  ( 
  247 
  ) 
  

  

  