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  53'] 
  GKEAT 
  JAPANESE 
  EARTHQUAKE 
  OF 
  1891. 
  15 
  

  

  PoSTSCRIPTUM. 
  

  

  [In 
  the 
  discussion 
  which 
  followed 
  the 
  reading 
  of 
  this 
  paper, 
  it 
  

   was 
  stated 
  that 
  'where 
  the 
  maps 
  showed 
  blank 
  spaces, 
  in 
  many- 
  

   cases 
  the 
  country 
  was 
  mountainous, 
  and 
  there 
  were 
  no 
  observers.' 
  

   This 
  probably 
  affords 
  a 
  partial, 
  but 
  not, 
  I 
  think, 
  a 
  complete 
  expla- 
  

   nation 
  of 
  the 
  paucity 
  of 
  epicentres 
  in 
  the 
  district 
  referred 
  to 
  herein, 
  

   for 
  it 
  would 
  only 
  apply 
  to 
  very 
  slight 
  earthquakes. 
  It 
  is 
  obvious 
  

   that 
  the 
  stronger 
  shocks 
  (if 
  there 
  were 
  any) 
  originating 
  within 
  the 
  

   mountainous 
  region 
  would 
  be 
  observed 
  in 
  the 
  surrounding 
  country, 
  

   and 
  the 
  resulting 
  records 
  would 
  enable 
  the 
  positions 
  of 
  the 
  epicentres 
  

   to 
  be 
  determined.— 
  Nov. 
  20th, 
  1896.] 
  

  

  Discussion. 
  

  

  Prof. 
  Milne 
  said 
  that 
  the 
  Mino-Owari 
  earthquake 
  had 
  furnished 
  

   a 
  greater 
  number 
  and 
  a 
  more 
  varied 
  series 
  of 
  seismic 
  phenomena 
  for 
  

   analysis 
  than 
  had 
  been 
  noted 
  in 
  connexion 
  with 
  any 
  disturbance 
  

   previously 
  recorded. 
  When 
  this 
  earthquake 
  took 
  place 
  an 
  enormous 
  

   fault, 
  which 
  can 
  be 
  traced 
  over 
  a 
  length 
  of 
  more 
  than 
  40 
  miles, 
  

   appeared 
  upon 
  the 
  surface, 
  and 
  it 
  was 
  usually 
  supposed 
  that 
  the 
  

   sudden 
  rupture 
  and 
  displacement 
  of 
  vast 
  masses 
  of 
  material 
  along 
  

   this 
  line 
  were 
  the 
  cause 
  of 
  the 
  earthquake. 
  

  

  On 
  account 
  of 
  a 
  peculiar 
  distribution 
  of 
  shocks 
  which 
  took 
  place 
  

   prior 
  to 
  1891, 
  Dr. 
  Davison 
  argued 
  that 
  the 
  fault 
  or 
  faults 
  in 
  the 
  

   Mino-Owari 
  district 
  were 
  outlined 
  before 
  the 
  occurrence 
  of 
  the 
  great 
  

   earthquake, 
  which 
  was, 
  therefore, 
  only 
  the 
  result 
  of 
  their 
  extension. 
  

   This 
  may 
  have 
  been 
  so, 
  but 
  it 
  must 
  be 
  remembered 
  that 
  before 
  1891 
  

   the 
  number 
  of 
  shocks 
  occurring 
  in 
  the 
  Mino-Owari 
  plain 
  were 
  not 
  

   numerous 
  ; 
  and 
  as 
  we 
  pass 
  from 
  1889 
  to 
  1891 
  we 
  cannot 
  say 
  that 
  

   they 
  increased 
  in 
  n 
  amber, 
  while 
  their 
  distribution, 
  as 
  exhibited 
  by 
  

   maps, 
  was 
  largely 
  dependent 
  upon 
  the 
  observing-stations. 
  Where 
  

   the 
  maps 
  showed 
  blank 
  spaces, 
  in. 
  many 
  cases 
  the 
  country 
  was 
  

   mountainous, 
  and 
  there 
  were 
  no 
  observers. 
  The 
  present 
  Author's 
  

   method 
  of 
  treatment 
  of 
  the 
  statistics 
  relating 
  to 
  ' 
  after-shocks 
  ' 
  no 
  

   doubt 
  possesses 
  advantages 
  over 
  that 
  previously 
  used 
  by 
  Prof. 
  Omori, 
  

   but 
  the 
  results 
  arrived 
  at, 
  so 
  far 
  as 
  they 
  are 
  comparable, 
  closely 
  

   accord. 
  It 
  was 
  at 
  the 
  speaker's 
  suggestion 
  that 
  the 
  study 
  of 
  after- 
  

   shocks 
  was 
  undertaken, 
  and 
  he 
  must 
  congratulate 
  Prof. 
  Omori 
  on 
  

   having 
  obtained 
  results 
  far 
  beyond 
  and 
  of 
  greater 
  importance 
  than 
  

   anything 
  anticipated 
  at 
  the 
  outset. 
  Prof. 
  Omori 
  added 
  to 
  our 
  

   knowledge 
  respecting 
  the 
  expiring 
  efforts 
  in 
  a 
  seismic 
  area; 
  while 
  

   Dr. 
  Davison, 
  among 
  other 
  things, 
  has 
  thrown 
  new 
  light 
  upon 
  the 
  

   change 
  in 
  subterranean 
  conditions 
  which 
  culminated, 
  on 
  October 
  

   28th, 
  1891, 
  in 
  a 
  shaking 
  which 
  could 
  be 
  recorded 
  from 
  pole 
  to 
  pole. 
  

  

  The 
  Rev. 
  Edwin 
  Hill 
  remarked 
  upon 
  the 
  extreme 
  interest 
  of 
  the 
  

   earthquakes 
  described. 
  

  

  Mr. 
  D. 
  Paul 
  also 
  spoke. 
  

  

  