﻿Miscellaneous 
  Intelligence. 
  305 
  

  

  kilos 
  (over 
  3,000 
  pounds), 
  while 
  the 
  average 
  weight 
  of 
  each 
  kind 
  

   is 
  3-3 
  kilos 
  (7£ 
  pounds). 
  Each 
  specimen 
  is 
  described 
  and 
  a 
  series 
  

   of 
  six 
  plates, 
  most 
  of 
  these 
  of 
  etched 
  plates, 
  adds 
  to 
  the 
  value 
  of 
  

   the 
  volume. 
  

  

  III. 
  Miscellaneous 
  Scientific 
  Intelligence. 
  

  

  1. 
  Earthquakes 
  in 
  Japan. 
  — 
  A 
  recent 
  number 
  of 
  the 
  Journal 
  of 
  

   the 
  College 
  of 
  Science 
  of 
  Tokyo 
  (vol. 
  xi, 
  pt. 
  iv) 
  contains 
  the 
  

   Earthquake 
  Investigation 
  Committee 
  catalogue 
  of 
  Japanese 
  earth- 
  

   quakes 
  since 
  the 
  earliest 
  times, 
  by 
  the 
  late 
  Prof. 
  Sekiya. 
  This 
  

   report 
  is 
  discussed 
  in 
  the 
  article 
  following 
  by 
  Prof. 
  Omori, 
  with 
  

   respect 
  to 
  the 
  number 
  of 
  earthquakes, 
  their 
  chronological 
  distri- 
  

   bution, 
  variation 
  with 
  the 
  season, 
  and 
  other 
  points. 
  The 
  total 
  

   number 
  of 
  destructive 
  earthquakes 
  in 
  Japan 
  from 
  the 
  year 
  416 
  

   A. 
  D. 
  to 
  the 
  end 
  of 
  1898 
  is 
  222. 
  Of 
  these, 
  but 
  few 
  were 
  recorded 
  

   in 
  the 
  fifth, 
  sixth, 
  and 
  seventh 
  centuries, 
  probably 
  because 
  of 
  the 
  

   imperfection 
  of 
  historical 
  records 
  in 
  those 
  earlier 
  times. 
  Begin- 
  

   ning, 
  however, 
  with 
  December 
  678, 
  there 
  are 
  recorded 
  220 
  destruc- 
  

   tive 
  earthquakes 
  in 
  the 
  interval 
  of 
  1220 
  years 
  to 
  the 
  end 
  of 
  1898, 
  

   or 
  one 
  for 
  about 
  every 
  five 
  and 
  a-half 
  years. 
  Were 
  the 
  records 
  of 
  

   earlier 
  parts 
  of 
  this 
  period 
  more 
  complete, 
  this 
  interval 
  would 
  

   undoubtedly 
  be 
  shorter. 
  In 
  the 
  interval 
  of 
  nearly 
  300 
  years, 
  from 
  

   the 
  beginning 
  of 
  the 
  seventh 
  century 
  to 
  the 
  end 
  of 
  1898, 
  there 
  

   were 
  108 
  destructive 
  earthquakes 
  in 
  Japan 
  ; 
  irom 
  which 
  it 
  is 
  con- 
  

   cluded 
  that 
  one 
  part 
  or 
  another 
  of 
  Japan 
  (except 
  Formosa) 
  is 
  

   likely 
  to 
  be 
  visited, 
  on 
  the 
  average, 
  once 
  in 
  nearly 
  two 
  and 
  a-half 
  

   to 
  three 
  years. 
  

  

  With 
  respect 
  to 
  the 
  distribution 
  through 
  the 
  year, 
  it 
  is 
  found 
  that 
  

   of 
  216 
  destructive 
  earthquakes, 
  48 
  occurred 
  in 
  the 
  spring, 
  74 
  in 
  the 
  

   summer, 
  49 
  in 
  the 
  autumn, 
  and 
  45 
  in 
  the 
  winter. 
  The 
  maximum 
  

   monthly 
  number 
  of 
  32 
  occurred 
  in 
  August, 
  and 
  the 
  minimum 
  of 
  

   10 
  in 
  January. 
  The 
  frequency 
  of 
  ordinary 
  small 
  shocks, 
  however, 
  

   is 
  found 
  to 
  be 
  a 
  minimum 
  in 
  the 
  months 
  of 
  June, 
  July, 
  August, 
  

   and 
  September; 
  in 
  other 
  words, 
  just 
  the 
  reverse 
  of 
  the 
  severe 
  

   earthquakes. 
  This 
  fact, 
  however, 
  admits 
  of 
  explanation, 
  as 
  shown 
  

   by 
  the 
  author, 
  since 
  the 
  constant 
  occurrence 
  of 
  small 
  earthquakes 
  

   in 
  an 
  unstable 
  country 
  like 
  Japan 
  may 
  be 
  regarded 
  as 
  maintain- 
  

   ing 
  the 
  region 
  in 
  a 
  normal 
  safe 
  condition, 
  thereby 
  preventing 
  any 
  

   abnormal 
  condition 
  of 
  stress 
  in 
  the 
  earth's 
  crust. 
  Their 
  non- 
  

   occurrence, 
  however, 
  may 
  cause 
  an 
  accumulation 
  of 
  stress, 
  facilitat- 
  

   ing 
  the 
  occurrence 
  of 
  destructive 
  seismic 
  disturbances. 
  

  

  Discussing 
  graphically 
  the 
  distribution 
  of 
  the 
  earthquakes 
  in 
  

   Japan 
  from 
  the 
  eighth 
  century 
  on, 
  it 
  is 
  found 
  that 
  this 
  is 
  not 
  uni- 
  

   form 
  but 
  rather 
  in 
  groups 
  ; 
  in 
  other 
  words, 
  that 
  destructive 
  earth- 
  

   quakes, 
  while 
  sometimes 
  happening 
  isolated, 
  tend 
  to 
  occur 
  in 
  

   groups 
  in 
  epochs 
  of 
  maximum 
  frequency. 
  The 
  geographical 
  dis- 
  

   tribution 
  of 
  the 
  earthquakes 
  in 
  the 
  different 
  parts 
  of 
  the 
  country 
  

   is 
  also 
  minutely 
  discussed. 
  

  

  2. 
  On 
  the 
  Propagation 
  of 
  Earthquake 
  Motion 
  to 
  great 
  Dis- 
  

  

  