﻿XX 
  OLDHAM: 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  severe 
  earthquake. 
  For 
  instance, 
  degree 
  IV 
  specifies, 
  as 
  a 
  part 
  of 
  its 
  characters, 
  

   the 
  disturbance 
  of 
  doors, 
  etc.; 
  in 
  the 
  case 
  of 
  the 
  1897 
  shock, 
  this 
  was 
  recorded 
  at 
  

   Sehore 
  in 
  Central 
  India 
  and 
  at 
  Bangalore, 
  yet 
  these 
  places 
  were 
  beyond 
  the 
  

   region 
  where 
  the 
  earthquake 
  could 
  be 
  distinctly 
  felt, 
  and 
  would 
  fall, 
  at 
  the 
  outside, 
  

   in 
  degree 
  I 
  of 
  the 
  Rossi-Forel 
  Scale. 
  Another 
  objection 
  is 
  its 
  limited 
  range. 
  The 
  

   area 
  which, 
  in 
  1S97, 
  was 
  covered 
  by 
  the 
  maximum 
  degree, 
  No. 
  X, 
  of 
  the 
  

   Rossi-Forel 
  Scale 
  is 
  as 
  large 
  as 
  England, 
  and 
  within 
  it 
  there 
  were 
  variations 
  of 
  

   violence, 
  or, 
  as 
  ordinarily 
  called, 
  intensity, 
  which 
  would 
  require 
  the 
  scale 
  to 
  be 
  

   extended 
  for 
  at 
  least 
  another 
  5 
  to 
  10 
  degrees. 
  1 
  

  

  63. 
  The 
  fact 
  is 
  that 
  the 
  word 
  intensity 
  as 
  ordinarily 
  used, 
  and 
  as 
  it 
  is 
  attempted 
  

   to 
  be 
  defined 
  in 
  these 
  scales 
  — 
  which 
  were 
  intended 
  to 
  serve 
  in 
  seismology 
  the 
  

   purpose 
  which 
  Moh's 
  scale 
  of 
  hardness 
  serves 
  in 
  mineralogy 
  — 
  is 
  altogether 
  too 
  

   vague 
  and 
  indefinite 
  a 
  term 
  to 
  be 
  used 
  in 
  scientific 
  description. 
  Prof. 
  Menden- 
  

   hall 
  has 
  pointed 
  out 
  that 
  there 
  are 
  three 
  distinct 
  quantities 
  which 
  have 
  been 
  or 
  may 
  

   be 
  used 
  as 
  measures 
  of 
  the 
  so-called 
  intensity 
  at 
  a 
  given 
  locality. 
  They 
  are 
  — 
  

  

  (1) 
  the 
  maximum 
  velocity 
  of 
  wave-particle, 
  

  

  (2) 
  the 
  maximum 
  acceleration 
  of 
  wave-particle, 
  

  

  (3) 
  the 
  energy 
  of 
  the 
  earthquake, 
  which 
  may 
  be 
  measured 
  by 
  (a) 
  the 
  energy 
  

  

  contained 
  in 
  a 
  unit 
  volume 
  of 
  rock 
  set 
  in 
  motion 
  by 
  the 
  wave, 
  (b) 
  the 
  

   rate 
  at 
  which 
  energy 
  is 
  transmitted 
  across 
  a 
  unit 
  area 
  of 
  the 
  wave 
  

   front. 
  

  

  Of 
  these, 
  (3) 
  in 
  one 
  of 
  its 
  forms 
  is 
  the 
  most 
  rational 
  and 
  scientific 
  equivalent 
  to 
  

   be 
  represented 
  by 
  the 
  word 
  intensity, 
  and, 
  of 
  the 
  two 
  forms, 
  (b) 
  is 
  that 
  which 
  Lord 
  

   Rayleigh 
  has 
  adopted 
  in 
  his 
  " 
  Theory 
  of 
  Sound 
  " 
  as 
  the 
  measure 
  of 
  intensity 
  of 
  

   radiation. 
  

  

  64. 
  Unfortunately 
  the 
  intensity, 
  in 
  this 
  sense, 
  is 
  incapable 
  of 
  direct 
  measurement, 
  

   and, 
  so 
  far, 
  has 
  not 
  been 
  satisfactorily 
  determined 
  in 
  the 
  case 
  of 
  any 
  earthquake. 
  

   As 
  ordinarily 
  used, 
  the 
  word 
  is 
  applied 
  to 
  the 
  greater 
  or 
  less 
  impression 
  produced 
  

   by 
  the 
  earthquake 
  on 
  the 
  senses 
  or 
  the 
  greater 
  or 
  less 
  destruction 
  wrought 
  by 
  it. 
  

  

  1 
  The 
  Rossi-Forel 
  Scale 
  of 
  Intensity. 
  — 
  Translated 
  by 
  Dr. 
  C. 
  Davison. 
  

   I. 
  Recorded 
  by 
  a 
  single 
  seismograph, 
  or 
  by 
  some 
  seismographs, 
  of 
  the 
  same 
  model, 
  but 
  

   not 
  by 
  several 
  seismographs 
  of 
  different 
  kinds; 
  the 
  shock 
  felt 
  by 
  an 
  experienced 
  

   observer. 
  

   II. 
  Recorded 
  by 
  seismographs 
  of 
  different 
  kinds; 
  felt 
  by 
  small 
  number 
  of 
  persons 
  at 
  rest. 
  

  

  III. 
  Felt 
  by 
  several 
  persons 
  at 
  rest 
  ; 
  strong 
  enough 
  for 
  the 
  duration 
  or 
  the 
  direction 
  to 
  be 
  

  

  appreciable. 
  

  

  IV. 
  Felt 
  by 
  persons 
  in 
  motion 
  ; 
  disturbance 
  of 
  moveable 
  objects, 
  door, 
  windows, 
  cracking 
  

  

  of 
  ceilings. 
  

  

  V. 
  Felt 
  generally 
  by 
  every 
  one; 
  disturbance 
  of 
  furniture 
  and 
  beds, 
  ringing 
  of 
  some 
  bells. 
  

   VI. 
  General 
  awakening 
  of 
  those 
  asleep 
  ; 
  general 
  ringing 
  of 
  bells, 
  oscillation 
  of 
  chandeliers, 
  

  

  stopping 
  of 
  clocks; 
  visible 
  disturbance 
  of 
  trees 
  and 
  shrubs. 
  Some 
  startled 
  persons 
  

   leave 
  their 
  dwellings. 
  

   VII. 
  Overthrow 
  of 
  moveable 
  objects, 
  fall 
  of 
  plaster, 
  ringing 
  of 
  church 
  bells, 
  general 
  panic, 
  

  

  without 
  damage 
  to 
  buildings. 
  

   VIII, 
  Fall 
  of 
  chimneys, 
  cracks 
  in 
  the 
  walls 
  of 
  buildings. 
  

   IX. 
  Partial 
  or 
  total 
  destruction 
  of 
  some 
  buildings. 
  

  

  X. 
  Great 
  disasters, 
  ruins, 
  disturbance 
  cf 
  strata, 
  fissures 
  in 
  the 
  earth's 
  crust, 
  rock-falls 
  

   from 
  mountains. 
  

  

  