﻿of 
  Matter 
  and 
  Mass. 
  21 
  

  

  it 
  attains 
  the 
  velocity 
  o£ 
  light 
  and 
  acquires 
  the 
  property, 
  

   mass. 
  Now 
  the 
  mass 
  of 
  a 
  body, 
  according 
  to 
  the 
  summary 
  

   of 
  the 
  writer 
  at 
  the 
  end 
  of 
  the 
  paper, 
  becomes 
  infinite 
  if 
  it 
  

   has 
  the 
  velocity 
  of 
  light. 
  To 
  escape 
  this 
  dilemma 
  either 
  

   light 
  must 
  move 
  with 
  a 
  velocity 
  less 
  than 
  the 
  velocity 
  of 
  

   light, 
  or 
  else 
  these 
  light-particles 
  must 
  be 
  a 
  new 
  creation 
  of 
  

   matter, 
  having 
  nothing 
  in 
  common 
  with 
  our 
  ideas 
  of 
  pon- 
  

   derable 
  matter. 
  Nor 
  do 
  their 
  unusual 
  properties 
  end 
  here. 
  

   If 
  the 
  energy 
  of 
  the 
  radiation 
  is 
  absorbed 
  the 
  particles 
  again 
  

   cease 
  to 
  be^ 
  vanish, 
  and 
  pass 
  into 
  the 
  unknowable. 
  They 
  

   are 
  ghosts 
  which 
  appear 
  and 
  disappear 
  at 
  the 
  will 
  of 
  the 
  

   necromancer. 
  Surely 
  we 
  should 
  pause 
  before 
  adopting 
  so 
  

   fantastic 
  a 
  view. 
  

  

  The 
  second 
  part 
  of 
  the 
  article 
  is 
  an 
  attempt 
  to 
  construct 
  a 
  

   new 
  system 
  of 
  mechanics. 
  In 
  this 
  system 
  we 
  may 
  retain 
  all 
  

   the 
  axioms 
  and 
  propositions 
  of 
  mechanics 
  previously 
  held 
  

   excepting 
  the 
  one 
  which 
  states 
  that 
  the 
  mass 
  of 
  a 
  body 
  is 
  

   independent 
  of 
  its 
  velocity. 
  For 
  this 
  we 
  should 
  substitute 
  

   that 
  mass 
  is 
  proportional 
  to 
  content 
  of 
  energy, 
  and 
  therefore 
  

   changes 
  with 
  velocity. 
  This 
  is 
  not 
  a 
  new 
  idea, 
  or 
  the 
  school 
  

   of 
  energetics 
  has 
  laboured 
  in 
  vain. 
  In 
  fact 
  any 
  treatise 
  on 
  

   hydrodynamics 
  arrives 
  at 
  the 
  same 
  conclusion, 
  except 
  that 
  

   we 
  usually 
  call 
  it 
  effective 
  or 
  apparent 
  mass. 
  But 
  the 
  deduc- 
  

   tions 
  from 
  this 
  axiom 
  will 
  repay 
  study 
  as 
  they 
  are 
  typical 
  of 
  

   a 
  new 
  movement 
  in 
  physics. 
  

  

  On 
  page 
  711 
  we 
  find 
  the 
  equation 
  

  

  d'^'=vd^ 
  (13) 
  

  

  where 
  E' 
  is 
  the 
  kinetic 
  energy, 
  M 
  the 
  momentum, 
  and 
  v 
  the 
  

   velocity 
  of 
  a 
  moving 
  body. 
  

   And 
  as 
  

  

  M 
  = 
  ?nv, 
  

  

  rfM 
  = 
  mdv 
  + 
  I'dm, 
  

  

  Since 
  the 
  mass 
  as 
  well 
  as 
  the 
  velocity 
  is 
  to 
  be 
  reckoned 
  a 
  

   variable^ 
  we 
  have 
  by 
  substitution 
  

  

  dEi' 
  = 
  mvdv 
  + 
  v^dm 
  (14) 
  

  

  Introducing 
  the 
  relation 
  of 
  mass 
  to 
  energy 
  given 
  in 
  

   equation 
  (7) 
  we 
  may 
  write 
  

  

  and 
  combining 
  this 
  equation 
  with 
  (14) 
  gives 
  

   Y^dm 
  = 
  mvdv 
  + 
  v^dm. 
  

   Here 
  again 
  we 
  have 
  the 
  unexplained 
  duality 
  of 
  the 
  mass 
  m, 
  

  

  