﻿of 
  Matter 
  and 
  Mass. 
  19 
  

  

  one. 
  The 
  discussion 
  of 
  these 
  theories 
  is 
  perhaps 
  more 
  readily 
  

   accomplished 
  by 
  a 
  review 
  o£ 
  a 
  paper 
  by 
  Dr. 
  G. 
  N. 
  Lewis*. 
  

  

  This 
  paper 
  is 
  an 
  ingenious 
  effort 
  to 
  reconcile 
  modern 
  ideas 
  

   and 
  Newtonian 
  mechanics. 
  In 
  it 
  the 
  writer 
  attempts 
  two 
  

   distinct 
  things: 
  first, 
  to 
  establish 
  a 
  quasi-corpuscular 
  theory 
  

   of 
  ]ight, 
  and 
  second, 
  to 
  explain 
  inertia, 
  wholly 
  or 
  in 
  part, 
  as 
  

   a 
  function 
  of 
  velocity. 
  

  

  We 
  may 
  pass 
  over 
  the 
  difficulties 
  all 
  corpuscular 
  theories 
  

   of 
  light 
  plimge 
  us 
  into 
  when 
  such 
  phenomena 
  as 
  interference, 
  

   polarization, 
  diffraction, 
  &c. 
  are 
  discussed, 
  as 
  they 
  are 
  not 
  

   touched 
  upon. 
  The 
  fallacy 
  of 
  his 
  hypothesis 
  lies 
  in 
  his 
  

   cardinal 
  assumption 
  " 
  That 
  a 
  beam 
  of 
  radiation 
  possesses 
  not 
  

   only 
  momentum 
  and 
  energy, 
  but 
  also 
  mass, 
  travelling 
  with 
  

   the 
  vC'Ocity 
  of 
  light, 
  and 
  that 
  a 
  body 
  absorbing 
  radiation 
  is 
  

   acquiring 
  this 
  mass 
  as 
  it 
  also 
  acquires 
  the 
  momentum 
  and 
  

   energy 
  of 
  the 
  radiation. 
  Therefore 
  a 
  body 
  which 
  absorbs 
  

   radiant 
  energy 
  increases 
  in 
  mass"t. 
  

  

  In 
  the 
  first 
  place, 
  the 
  assumption 
  made, 
  that 
  because 
  

   energy 
  is 
  involved 
  in 
  radiation, 
  and 
  because 
  a 
  black 
  body 
  

   absorbing 
  this 
  energy 
  is 
  moved 
  mechanicallj^, 
  therefore 
  

   radiation 
  is 
  due 
  to 
  a 
  mass 
  in 
  motion, 
  is 
  not 
  a 
  necessary 
  one. 
  

   Maxwell 
  proved 
  that 
  such 
  a 
  mechanical 
  action 
  must 
  occur 
  if 
  

   radiation 
  were 
  due 
  to 
  electromagnetic 
  waves, 
  and 
  Nichols 
  

   and 
  Hull 
  measured 
  the 
  effect 
  as 
  a 
  property 
  of 
  such 
  waves. 
  

  

  Secondly, 
  the 
  assumption 
  is 
  an 
  arbitrary 
  one, 
  contrary 
  to 
  

   our 
  experience. 
  As 
  an 
  illustration, 
  if 
  a 
  ball 
  moving 
  toward 
  

   a 
  man 
  were 
  stopped 
  by 
  his 
  hand 
  he 
  would 
  evidently 
  absorb 
  

   this 
  energy, 
  and 
  yet 
  no 
  one 
  would 
  claim 
  that 
  the 
  man 
  had 
  

   increased 
  in 
  mass. 
  Still 
  less 
  would 
  the 
  claim 
  be 
  made 
  if 
  the 
  

   ball 
  were 
  the 
  mass 
  of 
  a 
  beam 
  of 
  radiation 
  which, 
  according 
  

   to 
  Dr. 
  Lewis, 
  would 
  have 
  no 
  " 
  mass 
  if 
  it 
  were 
  at 
  rest, 
  or 
  

   indeed 
  if 
  it 
  were 
  moving 
  with 
  a 
  velocity 
  even 
  by 
  the 
  smallest 
  

   fraction 
  less 
  than 
  that 
  of 
  light."" 
  

  

  The 
  fallacy 
  in 
  the 
  assumption 
  is 
  even 
  more 
  clearly 
  seen 
  in 
  

   the 
  mathematical 
  deductions, 
  from 
  which 
  I 
  quote 
  : 
  

  

  '' 
  The 
  momentum 
  of 
  any 
  part 
  of 
  a 
  beam 
  of 
  radiation 
  having 
  

   the 
  mass 
  m 
  will 
  be 
  given 
  by 
  the 
  equation 
  

  

  li 
  = 
  m\ 
  (5) 
  

  

  The 
  increase 
  ^M 
  in 
  the 
  momentum 
  of 
  the 
  body 
  absorbing 
  

   the 
  radiation 
  will, 
  therefore, 
  equal 
  the 
  increase 
  dm 
  in 
  its 
  

  

  * 
  Lewis, 
  " 
  On 
  a 
  Revision 
  of 
  the 
  Fundamental 
  Laws 
  of 
  Matter 
  and 
  

   Energy," 
  Phil. 
  Mag. 
  vol. 
  xvi. 
  p. 
  705 
  (1908). 
  

   + 
  /:: 
  c. 
  p. 
  707. 
  

  

  C2 
  

  

  