﻿THE 
  UNFELT 
  EARTHQUAKE. 
  255 
  

  

  At 
  Edinburgh, 
  as 
  has 
  already 
  been 
  noticed, 
  I 
  am 
  indebted 
  to 
  the 
  

   Astronomer 
  Royal 
  for 
  the 
  information 
  that 
  there 
  is 
  a 
  small 
  but 
  

   distinct 
  disturbance 
  of 
  the 
  trace 
  at 
  14b. 
  6m. 
  

  

  From 
  the 
  observatory 
  at 
  the 
  Rocca 
  de 
  Papa, 
  Dr. 
  Cancani 
  most 
  

   obligingly 
  sent 
  a 
  tracing, 
  nearly 
  8 
  ft. 
  long, 
  of 
  the 
  record 
  of 
  the 
  

   horizontal 
  pendula 
  at 
  that 
  observatory, 
  and 
  on 
  this 
  I 
  notice 
  at 
  14I1. 
  

   4m,, 
  two 
  distinct 
  though 
  minute 
  undulations 
  and 
  again 
  between 
  

   14I1. 
  7m. 
  and 
  14I1. 
  8m. 
  some 
  more. 
  Though 
  small 
  these 
  undulations 
  

   are 
  distinct, 
  and 
  like 
  the 
  great 
  ones 
  of 
  the 
  principal 
  disturbance, 
  

   have 
  a 
  complete 
  period 
  of 
  about 
  20 
  seconds. 
  

  

  A 
  photograph 
  of 
  the 
  record 
  at 
  Shide 
  shows 
  a 
  decided 
  enlarge- 
  

   ment 
  of 
  the 
  trace 
  from 
  14I1. 
  5m., 
  to 
  14b. 
  7m., 
  which 
  is 
  doubtless 
  

   due 
  to 
  the 
  same 
  disturbance. 
  

  

  Besides 
  these 
  I 
  find 
  in 
  the 
  detailed 
  account 
  published 
  in 
  the 
  

   Bulletin 
  of 
  the 
  Italian 
  Seismological 
  Society, 
  the 
  following: 
  — 
  

  

  At 
  Leghoru 
  oscillations 
  of 
  the 
  Tromometro 
  Egidi, 
  are 
  recorded 
  

   at 
  14I1. 
  10m. 
  1 
  The 
  extent 
  is 
  only 
  imm. 
  as 
  against 
  3'2mm. 
  

   of 
  the 
  great 
  undulations, 
  but 
  no 
  other 
  disturbance 
  is 
  recorded 
  

   between 
  13b. 
  42m. 
  and 
  15b. 
  45m. 
  

  

  At 
  Catania 
  a 
  slight 
  disturbance 
  of 
  the 
  grande 
  sismometografo 
  

   of 
  25m. 
  length 
  of 
  pendulum, 
  at 
  14b. 
  12m. 
  41s. 
  on 
  the 
  NE-SW 
  

   component. 
  9 
  

  

  At 
  Ischia 
  the 
  horizontal 
  pendula, 
  which 
  are 
  evidently 
  extremely 
  

   sensitive 
  instruments, 
  were 
  repeatedly 
  disturbed 
  between 
  2h. 
  and 
  

   3I1. 
  p.m. 
  and 
  it 
  is 
  impossible, 
  without 
  access 
  to 
  the 
  original 
  records, 
  

   to 
  identify 
  the 
  undulations 
  referred 
  to 
  here. 
  

  

  Tabulating 
  these 
  records, 
  as 
  is 
  done 
  below, 
  we 
  obtain 
  a 
  rate 
  of 
  

   travel 
  practically 
  identical 
  with 
  that 
  of 
  the 
  direct 
  passage 
  of 
  the 
  

   great 
  undulations 
  from 
  the 
  centre. 
  

  

  1 
  Boll. 
  Soc. 
  Sismol, 
  Ital. 
  Ill, 
  pt. 
  ii, 
  p, 
  251. 
  

   s 
  Loc. 
  cit. 
  pp. 
  283, 
  284. 
  

  

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  255 
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