﻿510 
  Messrs. 
  G. 
  N. 
  Lewis 
  and 
  R. 
  C. 
  Tolman 
  on 
  the 
  

  

  in 
  outline 
  Table 
  XIII., 
  o£ 
  which 
  it 
  may 
  be 
  said 
  to 
  be 
  a 
  con- 
  

   tinuation. 
  The 
  values 
  of 
  'Xca 
  calculated 
  by 
  means 
  o£ 
  the 
  

   values 
  of 
  Hca, 
  omitting 
  those 
  referring 
  to 
  water, 
  methyl 
  

   alcohol, 
  and 
  propyl 
  alcohol, 
  agree 
  approximately 
  with 
  the 
  

   values 
  contained 
  in 
  the 
  third 
  column 
  which 
  w^ere 
  derived 
  

   directly 
  from 
  experimental 
  data. 
  The 
  agreement 
  is, 
  how^ever, 
  

   not 
  so 
  good 
  as 
  that 
  exhibited 
  in 
  Table 
  XIII. 
  From 
  the 
  way 
  

   equation 
  (14) 
  was 
  obtained 
  it 
  is 
  obvious 
  that 
  this 
  must 
  be 
  due 
  

   to 
  deviations 
  from 
  the 
  relation 
  expressed 
  by 
  equation 
  (13). 
  

  

  Cambridge, 
  June 
  24, 
  1909. 
  

  

  LYII. 
  The 
  Principle 
  of 
  Relativity^ 
  and 
  Non-Newtonian 
  

   Mechanics. 
  By 
  Gilbert 
  N. 
  Lewis 
  and 
  Eichard 
  C. 
  Tolman*. 
  

  

  UNTIL 
  a 
  few 
  years 
  ago 
  every 
  known 
  fact 
  about 
  light, 
  

   electricity, 
  and 
  magnetism 
  was 
  in 
  agreement 
  with 
  the 
  

   theory 
  of 
  a 
  stationary 
  medium 
  or 
  aether, 
  pervading 
  all 
  space, 
  

   but 
  offering 
  no 
  resistance 
  to 
  the 
  motion 
  of 
  ponderable 
  matter. 
  

   This 
  theory 
  of 
  a 
  stagnant 
  sether 
  led 
  to 
  the 
  belief 
  that 
  the 
  

   absolute 
  velocity 
  of 
  the 
  earth 
  through 
  this 
  medium 
  could 
  be 
  

   determined 
  by 
  optical 
  and 
  electrical 
  measurements. 
  Thus 
  it 
  

   was 
  predicted 
  that 
  the 
  time 
  required 
  for 
  a 
  beam 
  of 
  light 
  to 
  

   pass 
  over 
  a 
  given 
  distance, 
  from 
  a 
  fixed 
  point 
  to 
  a 
  mirror 
  

   and 
  back, 
  should 
  be 
  different 
  in 
  a 
  path 
  lying 
  in 
  the 
  direction 
  

   of 
  the 
  earth's 
  motion 
  and 
  in 
  a 
  path 
  lying 
  at 
  right 
  angles 
  to 
  

   this 
  line 
  of 
  motion. 
  This 
  prediction 
  was 
  tested 
  in 
  the 
  crucial 
  

   experiment 
  of 
  Michelson 
  and 
  Morley 
  t? 
  who 
  found, 
  in 
  spite 
  

   of 
  the 
  extreme 
  precision 
  of 
  their 
  method, 
  not 
  the 
  slightest 
  

   difference 
  in 
  the 
  different 
  paths. 
  

  

  It 
  was 
  also 
  predicted 
  from 
  the 
  aether 
  theory 
  that 
  a 
  charged 
  

   condenser 
  suspended 
  by 
  a 
  wire 
  would 
  be 
  subject 
  to 
  a 
  torsional 
  

   effect 
  due 
  to 
  the 
  earth's 
  motion. 
  But 
  the 
  absence 
  of 
  this 
  

   effect 
  was 
  proved 
  experimentally 
  by 
  Trouton 
  and 
  Noble 
  %. 
  

  

  The 
  skill 
  with 
  which 
  these 
  experiments 
  were 
  designed 
  and 
  

   executed 
  permits 
  no 
  serious 
  doubt 
  as 
  to 
  the 
  accuracy 
  of 
  their 
  

   results, 
  and 
  we 
  are 
  therefore 
  forced 
  to 
  adopt 
  certain 
  new 
  

   views 
  of 
  far-reaching 
  importance. 
  

  

  It 
  is 
  true 
  that 
  the 
  results 
  of 
  Michelson 
  and 
  Morley 
  might 
  

   be 
  simply 
  explained 
  by 
  assuming 
  that 
  the 
  velocity 
  of 
  light 
  

   depends 
  upon 
  the 
  velocity 
  of 
  its 
  source. 
  Perhaps 
  this 
  

   assumption 
  has 
  formerly 
  been 
  dismissed 
  without 
  sufficient 
  

  

  * 
  Communicated 
  by 
  the 
  Authors. 
  

  

  t 
  Amer. 
  Jour. 
  Sci. 
  xxxiv. 
  p. 
  333 
  (1887). 
  

  

  t 
  Phil. 
  Trans. 
  Koy. 
  Soc. 
  (A) 
  ccii. 
  p. 
  165 
  (1904). 
  

  

  