﻿212 
  OLDHAM: 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  ether 
  gardens, 
  even 
  as 
  far 
  as 
  the 
  Sibsagar 
  district, 
  but 
  have 
  no 
  

   further 
  particulars. 
  

  

  The 
  earliest 
  instance 
  of 
  the 
  rotation 
  of 
  objects 
  by 
  an 
  earthquake, 
  

   of 
  which 
  I 
  can 
  find 
  any 
  published 
  record, 
  is 
  in 
  the 
  account 
  of 
  the 
  

   Calabrian 
  Earthquake 
  of 
  1783 
  by 
  Michele 
  Sarconi, 
  Secretary 
  to 
  the 
  

   Neapolitan 
  Academy 
  of 
  Science 
  and 
  Letters. 
  1 
  His 
  figures 
  of 
  the 
  

   dislocation 
  of 
  the 
  obelisk-shaped 
  pillars 
  at 
  either 
  end 
  of 
  the 
  facade 
  of 
  

   the 
  Certosa 
  di 
  S. 
  Bruno 
  have 
  been 
  made 
  classic 
  by 
  their 
  reproduction 
  

   in 
  Sir 
  C. 
  LyelPs 
  " 
  Principles 
  of 
  Geology/' 
  and 
  in 
  the 
  description 
  

   is 
  stated, 
  what 
  appears 
  to 
  have 
  been 
  overlooked 
  by 
  most 
  of 
  his 
  

   successors 
  who 
  have 
  proposed 
  or 
  accepted 
  other 
  explanations, 
  that 
  

   one 
  of 
  the 
  obelisk-shaped 
  pillars 
  was 
  twisted 
  from 
  right 
  to 
  left, 
  and 
  

   the 
  other 
  from 
  left 
  to 
  right, 
  while 
  the 
  twisting 
  is 
  accepted 
  as 
  evidence 
  

   of 
  the 
  " 
  orrizontale 
  vorticoso 
  " 
  nature 
  of 
  the 
  shock. 
  This 
  explanation, 
  

   the 
  only 
  one 
  prevalent 
  at 
  the 
  time, 
  remained 
  unquestioned, 
  till 
  

   the 
  publication 
  of 
  Charles 
  Darwin's 
  " 
  Naturalist's 
  Voyage 
  round 
  the 
  

   World," 
  where 
  (Chapter 
  XIV), 
  after 
  noticing 
  the 
  effect 
  of 
  the 
  earths 
  

   quake 
  of 
  20th 
  February, 
  1835,,. 
  in 
  causing 
  the 
  rotation 
  cf 
  some 
  square 
  

   objects 
  on 
  the 
  coping 
  of 
  the 
  Cathedral 
  walls 
  at 
  Coneepcion 
  he 
  says 
  :— 
  

   "This 
  twisting 
  displacement 
  at 
  first 
  appears 
  to 
  indicate 
  a 
  vorticose 
  

   movement 
  beneath 
  each 
  point 
  thus 
  affected 
  ; 
  but 
  this 
  is 
  highly 
  im- 
  

   probable." 
  He 
  suggests 
  as 
  an 
  explanation 
  that 
  it 
  was 
  caused 
  by 
  a 
  

   tendency 
  in 
  each 
  stone 
  to 
  arrange 
  itself 
  in 
  some 
  particular 
  position 
  

   with 
  respect 
  to 
  the 
  lines 
  of 
  vibration 
  in 
  a 
  manner 
  somewhat 
  similar 
  to 
  

   pins 
  on 
  a 
  sheet 
  of 
  paper 
  when 
  shaken. 
  

  

  The 
  next 
  attempt 
  to 
  explain 
  this 
  phenomenon 
  is 
  that 
  of 
  Mr. 
  R. 
  

   Mallet, 
  2 
  who, 
  rejecting 
  the 
  vorticose 
  theory 
  and 
  the 
  suggestion 
  of 
  

   Mr. 
  Darwin, 
  proposed 
  an 
  explanation 
  of 
  his 
  own 
  which 
  has 
  found 
  its 
  

   way 
  into 
  most 
  text-books, 
  and 
  may 
  be 
  given 
  in 
  his 
  own 
  words. 
  

  

  " 
  If 
  a 
  stone, 
  whether 
  symmetrical 
  or 
  otherwise, 
  rest 
  upon 
  a 
  given 
  base, 
  and 
  

   motion 
  be 
  suddenly 
  communicated 
  horizontally 
  to 
  that 
  base 
  in 
  any 
  direction, 
  the 
  

  

  1 
  ' 
  Istcriade 
  Fenomeni 
  del 
  Tremoto 
  avvenuto 
  nelle 
  Calabria, 
  e 
  nel 
  Valdemone, 
  nell 
  ' 
  anno 
  

   1783 
  ; 
  posta 
  in 
  luce 
  dalla 
  Reale 
  Accademia 
  delle 
  Scienze, 
  e 
  delle 
  Belte 
  Lettere, 
  di 
  NapoJi. 
  

   Folio, 
  Naples 
  1784, 
  p. 
  62 
  and 
  PI. 
  XXI. 
  

  

  2 
  Jour 
  : 
  Geol. 
  Soc. 
  Dublin 
  III, 
  138-144 
  (1845). 
  See 
  also 
  his 
  paper 
  on 
  the 
  Dynamics 
  0$ 
  

   Earthquakes 
  : 
  Trans. 
  Roy. 
  Irish 
  Academy 
  XK\, 
  51-105 
  (1846). 
  

  

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  212 
  ) 
  

  

  

  