﻿THE 
  

   LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
  MAGAZINE 
  

  

  AND 
  

  

  JOURNAL 
  OF 
  SCIENCE. 
  

  

  [SIXTH 
  SERIES.] 
  

  

  \ 
  -. 
  **«%, 
  

  

  JANUARY 
  1902V' 
  

  

  I. 
  On 
  the 
  Clustering 
  of 
  Gravitational 
  Matter 
  in 
  any 
  

  

  the 
  Universe. 
  By 
  Lord 
  Kelvin, 
  G.C.V.O., 
  F.R.S.* 
  

  

  GRAVITATIONAL 
  matter, 
  according 
  to 
  our 
  ideas 
  of 
  

   universal 
  gravitation, 
  would 
  be 
  all 
  matter. 
  Now 
  is 
  

   there 
  any 
  matter 
  which 
  is 
  not 
  subject 
  to 
  the 
  law 
  of 
  gravitation 
  ? 
  

   I 
  think 
  I 
  may 
  say 
  with 
  absolute 
  decision 
  that 
  there 
  is. 
  We 
  

   are 
  all 
  convinced, 
  with 
  our 
  President, 
  that 
  ether 
  is 
  matter, 
  

   but 
  we 
  are 
  forced 
  to 
  say 
  that 
  the 
  properties 
  of 
  molar 
  matter 
  

   are 
  not 
  to 
  be 
  looked 
  for 
  in 
  ether 
  as 
  generally 
  known 
  to 
  us 
  by 
  

   action 
  resulting 
  from 
  force 
  between 
  atoms 
  and 
  matter, 
  ether 
  

   and 
  ether, 
  and 
  atoms 
  of 
  matter 
  and 
  ether. 
  Here 
  I 
  am 
  

   illogical 
  when 
  I 
  say 
  between 
  matter 
  and 
  ether, 
  as 
  if 
  ether 
  

   were 
  not 
  matter. 
  It 
  is 
  to 
  avoid 
  an 
  illogical 
  phraseology 
  that 
  

   I 
  use 
  the 
  title 
  ' 
  gravitational 
  matter/ 
  Many 
  years 
  ago 
  I 
  gave 
  

   strong 
  reason 
  to 
  feel 
  certain 
  that 
  ether 
  was 
  outside 
  the 
  law 
  of 
  

   gravitation. 
  We 
  need 
  not 
  absolutely 
  exclude, 
  as 
  an 
  idea, 
  the 
  

   possibility 
  of 
  there 
  being 
  a 
  portion 
  of 
  space 
  occupied 
  by 
  ether 
  

   beyond 
  which 
  there 
  is 
  absolute 
  vacuum 
  — 
  no 
  ether 
  and 
  no 
  

   matter. 
  We 
  admit 
  that 
  that 
  is 
  something 
  that 
  one 
  could 
  think 
  

   of 
  ; 
  but 
  I 
  do 
  not 
  believe 
  any 
  living 
  scientific 
  man 
  considers 
  

   it 
  in 
  the 
  slightest 
  degree 
  probable 
  that 
  there 
  is 
  a 
  boundary 
  

   around 
  our 
  universe 
  beyond 
  which 
  there 
  is 
  no 
  ether 
  and 
  no 
  

   matter. 
  Well, 
  if 
  ether 
  extends 
  through 
  all 
  space, 
  then 
  it 
  is 
  

   certain 
  that 
  ether 
  cannot 
  be 
  subject 
  to 
  the 
  law 
  of 
  mutual 
  

   gravitation 
  between 
  its 
  parts, 
  because 
  if 
  it 
  were 
  subject 
  to 
  

  

  * 
  Communicated 
  by 
  the 
  Author, 
  having' 
  been 
  read 
  before 
  the 
  British 
  

   Association 
  at 
  the 
  Glasgow 
  meeting. 
  

  

  PhiL 
  Mag. 
  S. 
  6. 
  Vol. 
  3. 
  No 
  13. 
  Jan. 
  1902. 
  B 
  

  

  TWTNT7YTT 
  

  

  