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  LXXXIII. 
  On 
  the 
  Rings 
  of 
  Saturn. 
  

  

  To 
  the 
  Editors 
  of 
  the 
  Philosophical 
  Magazine. 
  

  

  Gentlemen, 
  — 
  

  

  THE 
  Philosophical 
  Magazine 
  for 
  April, 
  1908, 
  p. 
  469, 
  pub- 
  

   lishes 
  the 
  following 
  paragraph 
  written 
  by 
  Mr. 
  Percivai 
  

   Lowell 
  : 
  — 
  

  

  "Although 
  seen 
  by 
  all 
  the 
  observers 
  at 
  Flagstaff, 
  the 
  black 
  

   core 
  was 
  not 
  caught 
  by 
  Barnard 
  at 
  Yerkes, 
  nor 
  has 
  it 
  been 
  

   reported 
  from 
  the 
  Lick. 
  This, 
  however, 
  is 
  in 
  keeping 
  with 
  

   the 
  definition 
  at 
  the 
  first 
  place 
  disclosed 
  already 
  by 
  its 
  greater 
  

   space 
  penetration 
  for 
  stars." 
  

  

  Statements 
  similar 
  to 
  that 
  made 
  in 
  the 
  last 
  quoted 
  sentence 
  

   have 
  in 
  the 
  past 
  three 
  years 
  been 
  published 
  by 
  Mr. 
  Lowell 
  

   in 
  several 
  popular, 
  semi-popular, 
  and 
  technical 
  magazines; 
  

   and 
  it 
  seems 
  to 
  be 
  my 
  reluctant 
  and 
  unprofitable 
  duty 
  

   finally 
  to 
  take 
  note 
  of 
  them. 
  

  

  Recent 
  observations 
  at 
  the 
  Lick 
  Observatory 
  (soon 
  to 
  be 
  

   published 
  elsewhere) 
  show 
  that 
  Mr. 
  Lowell 
  is 
  not 
  justified 
  

   in 
  claiming 
  " 
  greater 
  space 
  penetration 
  for 
  stars 
  " 
  for 
  his 
  

   telescope. 
  But 
  his 
  article 
  in 
  this 
  Magazine, 
  quoted 
  from 
  

   above, 
  supplies 
  its 
  own 
  refutation 
  of 
  his 
  claim. 
  

  

  1st. 
  The 
  inner 
  condensation 
  in 
  Saturn's 
  rings, 
  seen 
  double 
  

   with 
  great 
  ease 
  by 
  Aitken, 
  using 
  the 
  36-inch 
  Lick 
  telescope, 
  

   and 
  with 
  some 
  difficulty 
  (on 
  account 
  of 
  poor 
  seeing), 
  but 
  cer- 
  

   tainly, 
  by 
  Barnard 
  using 
  the 
  40-inch 
  Yerkes 
  telescope, 
  was 
  

   not 
  seen 
  double 
  by 
  Lowell. 
  

  

  2nd. 
  Lowell 
  located 
  a 
  " 
  gap 
  " 
  or 
  a 
  " 
  most 
  conspicuously 
  

   vacant 
  spot 
  " 
  in 
  the 
  ring 
  system 
  5{ 
  n 
  west 
  from 
  the 
  ball 
  of 
  

   the 
  planet, 
  and 
  another 
  one 
  like 
  it 
  5 
  J" 
  east 
  of 
  the 
  ball. 
  

   Aitken, 
  observing 
  on 
  the 
  same 
  night, 
  noticed 
  that 
  the 
  light 
  

   was 
  relatively 
  very 
  weak 
  at 
  these 
  points 
  ; 
  but, 
  thanks 
  to 
  the 
  

   greater 
  light-collecting 
  power 
  of 
  the 
  36-inch 
  telescope, 
  he 
  

   was 
  able 
  to 
  see 
  with 
  certainty 
  a 
  faint 
  line 
  of 
  light 
  extending 
  

   right 
  across 
  each 
  of 
  Lowell's 
  "conspicuously 
  vacant 
  gaps." 
  

  

  Mt. 
  Hamilton, 
  California, 
  

   September 
  29, 
  1908. 
  

  

  W. 
  W. 
  Campbell, 
  

  

  Director 
  Lick 
  Observatory. 
  

  

  