﻿512 
  Scientific 
  Intelligence. 
  

  

  law 
  is 
  n'=:/x 
  where 
  n 
  = 
  index 
  of 
  refraction 
  and 
  jx 
  = 
  dielectric 
  

   constant. 
  

  

  The 
  results 
  of 
  the 
  authors 
  are 
  embodied 
  in 
  the 
  following 
  table 
  

   (A, 
  is 
  wave 
  length). 
  

  

  n 
  n 
  

  

  Dielectric. 
  /z 
  \//Lt 
  A 
  = 
  Qm 
  A 
  = 
  6 
  , 
  10~ 
  7 
  m 
  

  

  Fluid 
  paraffine 
  1'98 
  1*41 
  1-4=7 
  ) 
  1*48 
  

  

  Cooling 
  paraffiue 
  208 
  J-44 
  1-48 
  J 
  bis 
  

  

  Solid 
  paraffine. 
  1-95 
  1*40 
  1-43 
  1*53 
  

  

  Glass 
  I 
  5-37 
  2-32 
  2-33 
  1-51 
  

  

  Glass 
  II 
  ._ 
  590 
  2-43 
  2'49 
  1*53 
  

  

  Castor 
  oil 
  4-67 
  2-16 
  2-05 
  148 
  

  

  Olive 
  oil 
  3 
  07 
  1-75 
  1-77 
  1-47' 
  

  

  Xylol 
  2-35 
  1-53 
  1-50 
  1'49 
  

  

  Petroleum 
  2-07 
  1-44 
  1-40 
  1-45 
  

  

  — 
  Ann. 
  cler 
  Physik 
  und 
  Chemie, 
  No. 
  10, 
  1891, 
  pp. 
  206-213. 
  

  

  J. 
  T. 
  

  

  II. 
  Geology. 
  

  

  1. 
  On 
  the 
  British 
  Earthquakes 
  of 
  1889 
  ; 
  by 
  C. 
  Davison, 
  of 
  

   King 
  Edward's 
  High 
  School, 
  Birmingham, 
  (Geol. 
  Mag., 
  viii, 
  1 
  891.) 
  

   — 
  The 
  more 
  important 
  conclusions 
  of 
  Prof. 
  Davison's 
  paper 
  are 
  

   presented 
  in 
  the 
  following 
  citations 
  from 
  pages 
  10, 
  20 
  and 
  28. 
  

  

  I 
  believe 
  we 
  may, 
  with 
  some 
  probability, 
  conclude: 
  (l) 
  that 
  

   the 
  Edinburgh 
  earthquake 
  was 
  caused 
  by 
  a 
  slip 
  of 
  the 
  fault 
  

   marked 
  BB 
  on 
  the 
  map, 
  at 
  a 
  spot 
  vertically 
  below 
  the 
  position 
  

   indicated 
  for 
  the 
  epicentrum, 
  and 
  therefore 
  not 
  far 
  from 
  the 
  

   middle 
  of 
  the 
  fault, 
  where, 
  probably, 
  the 
  throw 
  is 
  a 
  maximum 
  

   and 
  where 
  earthquake-action 
  has 
  been 
  most 
  frequent 
  or 
  most 
  

   intense; 
  (2) 
  that, 
  on 
  account 
  of 
  the 
  simple 
  character 
  and 
  short 
  

   duration 
  of 
  the 
  disturbance, 
  the 
  horizontal 
  length 
  of 
  the 
  fault 
  

   over 
  which 
  the 
  slip 
  took 
  place 
  was 
  very 
  short, 
  possibly 
  less 
  than 
  

   a 
  mile 
  ; 
  (3) 
  that 
  the 
  slip 
  of 
  the 
  downthrow 
  side 
  was 
  downward 
  

   or 
  that 
  of 
  the 
  upthrow 
  side 
  upward, 
  resulting, 
  in 
  either 
  case, 
  in 
  

   an 
  increase 
  of 
  the 
  throw 
  of 
  the 
  fault 
  in 
  the 
  neighborhood 
  of 
  the 
  

   seismic 
  focus 
  j 
  and 
  (4) 
  that, 
  while 
  the 
  region 
  of 
  maximum 
  slip, 
  

   the 
  focus 
  of 
  the 
  earthquake 
  proper, 
  was 
  probably 
  at 
  a 
  depth 
  of 
  

   several 
  (perhaps 
  about 
  8) 
  miles, 
  the 
  slip 
  extended 
  upwards 
  to 
  

   within 
  a 
  short 
  distance 
  of 
  the 
  surface, 
  this 
  part 
  of 
  the 
  slip-area 
  

   being 
  the 
  focus 
  of 
  the 
  sound-vibrations. 
  — 
  p. 
  10. 
  

  

  In 
  both 
  the 
  Edinburgh 
  and 
  Lancashire 
  earthquakes, 
  the 
  

   shock 
  and 
  sound, 
  we 
  have 
  reason 
  to 
  believe, 
  were 
  caused 
  by 
  

   slipping 
  along 
  well-known 
  faults, 
  the 
  foci 
  of 
  the 
  sounds 
  being 
  

   nearer 
  the 
  surface 
  than 
  the 
  foci 
  of 
  the 
  corresponding 
  shocks. 
  In 
  

   both, 
  also, 
  the 
  area 
  over 
  which 
  the 
  slip 
  took 
  place 
  must 
  have 
  

   been 
  very 
  limited 
  in 
  extent 
  : 
  and, 
  while 
  the 
  amount 
  of 
  the 
  slip 
  

   may 
  have 
  been 
  greatest 
  near 
  the 
  center 
  of 
  the 
  Lancashire 
  area, 
  

   it 
  must 
  certainly 
  have 
  died 
  away 
  toward 
  its 
  upper 
  and 
  lateral 
  

   margins. 
  

  

  