﻿142 
  Sir 
  Oliver 
  Lodge 
  on 
  Astronomical 
  and 
  

  

  Newtonian 
  law 
  F 
  = 
  ymm 
  f 
  /r 
  2 
  , 
  the 
  varying 
  factor 
  m 
  will 
  enter 
  

   twice 
  into 
  the 
  equation 
  of 
  motion, 
  and 
  the 
  whole 
  perturbation 
  

   will 
  be 
  increased 
  instead 
  of 
  being 
  annihilated. 
  In 
  other 
  words, 
  

   if 
  the 
  gravitative 
  pull 
  on 
  the 
  planet 
  increases 
  in 
  the 
  same 
  

   way 
  as 
  the 
  inertia 
  increases, 
  the 
  effect 
  is 
  not 
  to 
  cancel, 
  but 
  to 
  

   double 
  the 
  perturbing 
  effect. 
  On 
  the 
  other 
  hand, 
  if 
  the 
  extra 
  

   inertia 
  is 
  not 
  affected 
  by 
  gravity 
  the 
  perturbing 
  effect 
  is 
  as 
  

   already 
  calculated. 
  Consequently 
  from 
  this 
  point 
  of 
  view 
  

   some 
  perturbation 
  seems 
  inevitable 
  ; 
  — 
  either 
  the 
  value 
  reckoned 
  

   by 
  me 
  in 
  August, 
  with 
  the 
  extra 
  inertia 
  independent 
  of 
  gravity, 
  

   or 
  else 
  double 
  that 
  value, 
  if 
  the 
  extra 
  inertia 
  is 
  fully 
  subject 
  

   to 
  the 
  Newtonian 
  law 
  of 
  attraction. 
  

  

  The 
  question 
  arises 
  therefore, 
  rather 
  pressingly, 
  how 
  much 
  

   dependence 
  can 
  be 
  placed 
  on 
  the 
  theory 
  ? 
  It 
  will 
  be 
  granted 
  

   I 
  think 
  that 
  the 
  fact 
  that 
  a 
  correct 
  value 
  for 
  Mercurial 
  apsidal 
  

   progress 
  can 
  be 
  deduced 
  from 
  the 
  electrical 
  theory 
  of 
  matter 
  

   by 
  a 
  reasonable 
  assumption 
  of 
  solar 
  drift 
  is 
  not 
  a 
  negligible 
  

   fact. 
  For 
  if 
  the 
  theory 
  were 
  completely 
  inapplicable 
  the 
  

   value 
  of 
  drift 
  required 
  might 
  have 
  been 
  of 
  an 
  altogether 
  

   unreasonable 
  order 
  of 
  magnitude. 
  The 
  fact 
  that 
  the 
  same 
  

   drift 
  gave 
  a 
  Martial 
  apsidal 
  progress 
  also 
  of 
  the 
  right 
  

   magnitude 
  (see 
  August 
  Phil. 
  Mag. 
  pp. 
  91 
  & 
  92) 
  seemed 
  to 
  

   me 
  at 
  the 
  time 
  very 
  confirmatory. 
  But 
  I 
  admit 
  that 
  the 
  

   changes 
  in 
  excentricity 
  are 
  not 
  thus 
  accounted 
  for 
  correctly, 
  

   and 
  that 
  the 
  calculated 
  perturbations 
  for 
  Earth 
  and 
  Yenus 
  

   exceed 
  any 
  probable 
  value 
  for 
  those 
  planets. 
  

  

  I 
  perceived 
  in 
  my 
  August 
  paper 
  that 
  a 
  difficulty 
  of 
  this 
  

   kind 
  would 
  arise, 
  but 
  thought 
  that 
  it 
  might 
  be 
  got 
  over 
  by 
  

   choosing 
  a 
  particular 
  longitude 
  for 
  the 
  projected 
  component 
  

   of 
  the 
  solar 
  drift 
  which 
  should 
  almost 
  nullify 
  the 
  result 
  for 
  

   those 
  two 
  planets 
  ; 
  and 
  so 
  I 
  chose 
  the 
  longitude 
  294° 
  as 
  

   being 
  half-way 
  between 
  the 
  perihelia 
  of 
  Mercury 
  and 
  Mars, 
  

   and 
  inclined 
  to 
  their 
  major 
  axes 
  at 
  a 
  reasonable 
  angle, 
  while 
  

   at 
  the 
  same 
  time 
  it 
  happens 
  to 
  be 
  practically 
  half-way 
  

   between 
  the 
  perihelia 
  of 
  Earth 
  and 
  Venus, 
  though 
  inclined 
  

   to 
  their 
  major 
  axes 
  at 
  a 
  much 
  smaller 
  angle, 
  and 
  so 
  being 
  

   less 
  effective. 
  I 
  hoped 
  therefore 
  that 
  it 
  might 
  be 
  possible 
  to 
  

   contrive 
  to 
  get 
  rid 
  of 
  the 
  calculated 
  too 
  great 
  progress 
  of 
  

   perihelion 
  for 
  Earth 
  and 
  Venus, 
  especially 
  as 
  the 
  roundness 
  

   of 
  their 
  orbits 
  must 
  make 
  the 
  exact 
  position 
  of 
  perihelion 
  

   difficult 
  to 
  determine. 
  

  

  Professor 
  Eddington, 
  however, 
  countered 
  all 
  this 
  con- 
  

   trivance, 
  in 
  September, 
  by 
  working 
  out 
  the 
  theoretical 
  

   changes 
  of 
  excentricity 
  more 
  thoroughly 
  than 
  I 
  had 
  done, 
  

   and 
  showed 
  that 
  it 
  was 
  highly 
  improbable 
  that 
  the 
  calculated 
  

   perturbations 
  could 
  be 
  admitted 
  for 
  some 
  and 
  evaded 
  for 
  

  

  