﻿Gravitational 
  Bearings 
  of 
  Electrical 
  Theory 
  of 
  Matter. 
  143 
  

  

  others 
  of 
  the 
  four 
  inner 
  planets, 
  by 
  any 
  judiciously 
  selected 
  

   direction 
  for 
  solar 
  drift. 
  

  

  If 
  therefore 
  the 
  theory 
  fails 
  to 
  give 
  all 
  the 
  known 
  pertur- 
  

   bations 
  correctly, 
  something 
  must 
  be 
  wrong 
  ; 
  and 
  by 
  rinding 
  

   out 
  what 
  is 
  wrong, 
  we 
  may 
  perhaps 
  discover 
  something 
  

   instructive. 
  At 
  first 
  I 
  thought 
  that 
  it 
  would 
  suffice 
  to 
  say 
  

   that 
  the 
  extra 
  inertia 
  must 
  after 
  all 
  be 
  fully 
  subject 
  to 
  

   gravity, 
  and 
  that 
  therefore 
  the 
  acceleration 
  was 
  unaltered. 
  

   But 
  in 
  the 
  light 
  of 
  Eddington's 
  improved 
  theory, 
  that 
  

   loop-hole 
  is 
  closed 
  ; 
  for 
  the 
  ratio 
  F/m 
  turns 
  out 
  not 
  to 
  be 
  

   really 
  involved. 
  So 
  the 
  alternative 
  that 
  next 
  occurred 
  to 
  me 
  

   was 
  to 
  suppose 
  that 
  the 
  gravitative 
  constant 
  7 
  may 
  likewise 
  

   be 
  a 
  function 
  of 
  velocity, 
  and 
  that 
  its 
  changes 
  act 
  in 
  a 
  com- 
  

   pensating 
  manner 
  ; 
  that 
  is 
  to 
  say, 
  that 
  the 
  7 
  for 
  bodies 
  

   in 
  motion 
  through 
  the 
  sether 
  differs 
  from 
  the 
  value 
  appro- 
  

   priate 
  for 
  bodies 
  at 
  rest 
  in 
  one 
  or 
  other 
  of 
  the 
  two 
  

   following 
  ways 
  : 
  — 
  

  

  -y=yo\/(i- 
  ?) 
  

  

  if 
  extra 
  inertia 
  is 
  independent 
  of 
  gravity, 
  

  

  7=70(1- 
  y 
  

  

  or 
  

  

  if 
  the 
  extra 
  inertia 
  has 
  its 
  full 
  complement 
  of 
  weight. 
  But 
  

   then, 
  so 
  far 
  as 
  I 
  know, 
  there 
  has 
  never 
  been 
  any 
  reason 
  for 
  

   suspecting 
  such 
  a 
  variability 
  in 
  the 
  ^Newtonian 
  gravitative 
  

   constant. 
  

  

  If 
  there 
  should 
  really 
  turn 
  out 
  to 
  be 
  such 
  a 
  change 
  in 
  the 
  

   value 
  of 
  the 
  gravitative 
  attraction 
  between 
  bodies 
  in 
  rapid 
  

   motion, 
  it 
  would 
  be 
  a 
  very 
  remarkable 
  and 
  noteworthy 
  fact, 
  

   and 
  one 
  that 
  would 
  serve 
  to 
  strengthen 
  belief 
  in 
  some 
  form 
  

   of 
  the 
  Principle 
  of 
  Relativity. 
  Hitherto 
  the 
  experimental 
  

   foundation 
  of 
  that 
  Principle 
  has 
  been 
  the 
  fact 
  that 
  whether 
  

   luminous 
  or 
  telegraphic 
  signals 
  were 
  used, 
  or 
  whether 
  the 
  

   interval 
  of 
  time 
  between 
  reception 
  and 
  transmission 
  of 
  

   signals 
  was 
  made 
  to 
  depend 
  on 
  cohesion 
  or 
  some 
  other 
  

   property 
  of 
  solid 
  matter, 
  there 
  was 
  always 
  a 
  disconcertingly 
  

   complete 
  compensation, 
  so 
  that 
  no 
  motion 
  of 
  matter 
  as 
  a 
  

   whole 
  through 
  the 
  aether 
  could 
  be 
  demonstrated. 
  I 
  had 
  

   hoped 
  that 
  by 
  aid 
  of 
  the 
  astronomical 
  perturbations 
  calculable 
  

   from 
  the 
  electrical 
  theory 
  of 
  matter 
  this 
  compensating 
  

   influence 
  might 
  be 
  overcome, 
  and 
  that 
  the 
  force 
  of 
  gravity 
  

   would 
  not, 
  so 
  to 
  speak, 
  join 
  the 
  conspiracy 
  to 
  defeat 
  our 
  

  

  M2 
  

  

  