﻿ME. 
  P. 
  EUTLET 
  ON 
  FULGTJEITES 
  EEOM 
  MONTE 
  YISO. 
  

  

  65 
  

  

  to 
  find 
  the 
  rock 
  altered 
  to 
  a 
  uniform 
  depth 
  around 
  the 
  lightning- 
  

   tube 
  *. 
  

  

  Throughout 
  this 
  paper 
  I 
  have 
  spoken 
  of 
  these 
  ramifying, 
  vitrified 
  

   grooves 
  as 
  tubes, 
  because 
  it 
  is 
  my 
  impression 
  that 
  the 
  lightning 
  did 
  

   not 
  produce 
  these 
  channels 
  upon 
  the 
  exposed 
  surfaces, 
  but 
  actually 
  

   penetrated 
  the 
  rock 
  ; 
  and 
  Mr. 
  Eccles 
  informed 
  me 
  that 
  he 
  saw 
  one 
  

   of 
  these 
  tubes 
  penetrating 
  the 
  rock 
  in 
  place 
  ; 
  unfortunately, 
  however, 
  

   the 
  difficulty 
  of 
  detaching 
  the 
  piece 
  of 
  stone, 
  without 
  crushing 
  the 
  

   tube, 
  prevented 
  him 
  from 
  securing 
  this 
  most 
  interesting 
  specimen. 
  

   Lightning-tubes 
  more 
  than 
  an 
  inch 
  in 
  diameter, 
  penetrating 
  an 
  

   andesitic 
  rock 
  on 
  the 
  summit 
  of 
  Little 
  Ararat, 
  have 
  also 
  been 
  

   described 
  by 
  Abich 
  as 
  far 
  back 
  as 
  1870 
  f 
  . 
  I 
  think 
  it 
  may 
  there- 
  

   fore 
  be 
  taken 
  for 
  granted 
  that 
  these 
  ramifying 
  channels 
  are 
  portions 
  

   of 
  tubes 
  laid 
  open 
  to 
  us 
  in 
  section 
  by 
  the 
  rock 
  having 
  been 
  split 
  

   along 
  planes 
  of 
  easy 
  fission. 
  

  

  Fig. 
  2. 
  

  

  ^ot 
  

  

  

  Another 
  interesting 
  problem 
  presents 
  itself 
  in 
  the 
  occurrence 
  of 
  

   minute 
  glassy 
  pellets 
  and 
  thin 
  vitrified 
  crusts 
  on 
  these 
  joint-planes 
  

   and 
  fractures. 
  Their 
  existence 
  is, 
  I 
  think, 
  to 
  be 
  accounted 
  for, 
  if 
  

   we 
  assume 
  that 
  the 
  lightning 
  as 
  it 
  penetrated 
  the 
  rock 
  also 
  split 
  

   and 
  shattered 
  it, 
  preferably 
  in 
  the 
  direction 
  of 
  pre-existing 
  structural 
  

   planes, 
  and, 
  just 
  as 
  a 
  flash 
  may 
  be 
  seen 
  to 
  emanate 
  from 
  the 
  breech- 
  

   joint 
  of 
  a 
  rifle 
  when 
  fired 
  in 
  the 
  dark, 
  so 
  we 
  may 
  conceive 
  that 
  the 
  

   flash 
  of 
  the 
  lightning 
  penetrated, 
  and 
  actually 
  prized 
  open, 
  the 
  joint- 
  

   planes 
  in 
  the 
  neighbourhood 
  of 
  the 
  tubes 
  which 
  it 
  formed, 
  in 
  this 
  

   instance 
  fusing 
  the 
  surfaces 
  along 
  which 
  it 
  passed. 
  

  

  The 
  occurrence 
  of 
  globulites, 
  margarites, 
  longulites, 
  and 
  micro- 
  

   liths 
  in 
  the 
  fulgurite 
  -glass 
  would 
  seem 
  to 
  indicate 
  a 
  less 
  sudden 
  

   cooling 
  of 
  the 
  fused 
  matter 
  than 
  is 
  assumed 
  to 
  be 
  usual 
  in 
  such 
  

  

  * 
  There 
  are, 
  however, 
  peculiar 
  contact-phenomena 
  to 
  be 
  observed 
  sometimes 
  

   where 
  taehylytic 
  glass 
  comes 
  against 
  a 
  rock-surface, 
  and 
  it 
  is 
  just 
  possible 
  that 
  

   this 
  may 
  be 
  a 
  similar 
  case. 
  Vide 
  " 
  Some 
  Additional 
  Occurrences 
  of 
  Tachylyte," 
  

   by 
  Grenville 
  A. 
  J. 
  Cole, 
  Quart. 
  Journ. 
  G-eol. 
  Soc. 
  vol. 
  xliv. 
  p. 
  301. 
  

  

  t 
  Sitzungsb. 
  d. 
  AJkad. 
  Wiss. 
  Wien, 
  vol. 
  lx. 
  p. 
  155. 
  

  

  a. 
  J. 
  G. 
  S. 
  No. 
  177. 
  f 
  

  

  