﻿144 
  Sir 
  Oliver 
  Lodge 
  on 
  Astronomical 
  and 
  

  

  object. 
  We 
  must, 
  however, 
  now 
  face 
  the 
  possibility 
  that 
  

   gravitation 
  too 
  obeys 
  a 
  compensating 
  law, 
  and 
  declines 
  to 
  

   enable 
  us 
  to 
  receive 
  information 
  about 
  absolute 
  motion 
  of 
  

   matter 
  through 
  aether. 
  

  

  We 
  must 
  face 
  the 
  possibility 
  : 
  I 
  do 
  not 
  say 
  we 
  must 
  

   accept 
  it 
  ; 
  but 
  it 
  becomes 
  necessary 
  to 
  consider 
  what 
  other 
  

   loop-holes 
  there 
  are 
  out 
  of 
  the 
  conclusion 
  which 
  has 
  thus 
  

   suggested 
  itself. 
  

  

  Is 
  it 
  possible 
  that 
  there 
  is 
  anything 
  wrong 
  about 
  the 
  

   theory 
  that 
  the 
  inertia 
  of 
  matter 
  is 
  increased 
  as 
  a 
  certain 
  

   function 
  of 
  the 
  speed 
  ? 
  There 
  can 
  hardly 
  be 
  any 
  doubt 
  

   about 
  it 
  for 
  an 
  isolated 
  charge 
  such 
  as 
  an 
  electron, 
  inasmuch 
  

   as 
  the 
  calculation 
  based 
  upon 
  the 
  behaviour 
  of 
  its 
  lines 
  of 
  

   force 
  is 
  very 
  straightforward, 
  and 
  because 
  in 
  the 
  case 
  of 
  

   certain 
  extra-high-speed 
  ejections 
  from 
  radium 
  the 
  extra 
  

   inertia 
  has 
  been 
  observed 
  and 
  measured 
  and 
  found 
  to 
  cor- 
  

   respond 
  with 
  theory. 
  

  

  But 
  it 
  may 
  be 
  argued 
  that 
  when 
  electrons 
  are 
  packed 
  

   together 
  into 
  an 
  atom, 
  — 
  positive 
  and 
  negative 
  together, 
  so 
  as 
  

   to 
  be 
  on 
  the 
  whole 
  neutral, 
  — 
  this 
  effect, 
  due 
  to 
  their 
  individual 
  

   electrostatic 
  lines 
  of 
  force, 
  is 
  masked, 
  and 
  that 
  the 
  whole 
  

   neutral 
  atom 
  ought 
  not 
  to 
  show 
  any 
  but 
  perhaps 
  a 
  residual 
  

   effect 
  of 
  that 
  kind. 
  

  

  Against 
  this 
  argument 
  I 
  urge 
  several 
  considerations 
  : 
  — 
  

   First, 
  that 
  if 
  the 
  inertia 
  of 
  the 
  negative 
  electron 
  is 
  wholly 
  

   electrical, 
  it 
  becomes 
  exceedingly 
  probable 
  that 
  all 
  inertia 
  is 
  

   of 
  that 
  kind 
  ; 
  and 
  if 
  so, 
  the 
  abolition 
  of 
  electrical 
  inertia 
  

   would 
  mean 
  the 
  abolition 
  of 
  all 
  inertia. 
  

  

  Secondly, 
  although 
  we 
  may 
  speak 
  of 
  electrons 
  as 
  " 
  packed 
  

   together 
  " 
  into 
  an 
  atom, 
  the 
  packing 
  is 
  very 
  far 
  from 
  being 
  

   close 
  ; 
  for 
  to 
  all 
  intents 
  and 
  purposes 
  they 
  are 
  well 
  sepa- 
  

   rated 
  from 
  each 
  other 
  and 
  almost 
  isolated, 
  even 
  though 
  several 
  

   are 
  contained 
  in 
  a 
  sphere 
  the 
  ten 
  -millionth 
  of 
  a 
  millimetre 
  

   in 
  diameter. 
  It 
  will 
  be 
  remembered 
  that 
  inertia 
  is 
  due 
  to 
  

   the 
  concentration 
  of 
  the 
  electric 
  charge, 
  and 
  this 
  concentration 
  

   is 
  only 
  marked 
  within 
  a 
  minute 
  distance 
  from 
  a 
  sphere 
  so 
  

   small 
  as 
  an 
  electron. 
  Taking 
  its 
  linear 
  dimensions 
  as 
  10 
  ~ 
  13 
  , 
  

   all 
  but 
  one-hundred-thousandth 
  of 
  the 
  inertia 
  lies 
  within 
  a 
  

   range 
  smaller 
  than 
  10~ 
  8 
  . 
  Regarding 
  the 
  electron 
  of 
  a 
  

   hydrogen 
  atom 
  as 
  a 
  sphere 
  an 
  inch 
  in 
  radius, 
  the 
  adjacent 
  

   opposite 
  charge 
  is 
  something 
  like 
  a 
  mile 
  away. 
  Moreover, 
  

   the 
  fields 
  of 
  opposite 
  charges 
  are 
  subject 
  to 
  the 
  law 
  of 
  simple 
  

   superposition. 
  And 
  again, 
  the 
  inertia 
  in 
  superposed 
  fields 
  of 
  

   force 
  does 
  not 
  depend 
  on 
  the 
  sign 
  of 
  each 
  component, 
  but 
  is 
  

   proportional 
  to 
  the 
  square 
  of 
  each 
  component. 
  Consequently 
  

   there 
  seems 
  no 
  adequate 
  reason 
  against 
  merely 
  adding 
  their 
  

  

  