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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  the 
  lightest 
  elements 
  survive 
  for 
  longest 
  the 
  disintegrating 
  action 
  oi 
  

   time, 
  so 
  that 
  ultimately 
  the 
  star 
  contains 
  only 
  the 
  lightest 
  elements 
  

   of 
  all 
  and 
  so 
  has 
  lost 
  all 
  radiating 
  power. 
  Our 
  terrestrial 
  elements 
  

   have 
  so 
  little 
  capacity 
  for 
  spontaneous 
  transformation 
  that 
  they 
  may 
  

   properly 
  be 
  described 
  as 
  "permanent." 
  Calculation 
  shows 
  that 
  if 
  

   they 
  underwent 
  any 
  appreciable 
  transformation 
  in 
  periods 
  com- 
  

   parable 
  with 
  the 
  life 
  of 
  a 
  star 
  (say 
  10'^ 
  years) 
  the 
  spontaneous 
  gen- 
  

   eration 
  of 
  heat 
  by 
  the 
  earth's 
  mass 
  would 
  make 
  the 
  earth 
  too 
  hot 
  for 
  

   human 
  habitation. 
  The 
  radioactive 
  elements 
  are, 
  of 
  course, 
  an 
  

   exception; 
  they 
  probably 
  represent 
  the 
  last 
  surviving 
  vestiges 
  of 
  

   more 
  vigorous 
  primeval 
  matter, 
  and 
  so 
  form 
  a 
  bridge 
  between 
  the 
  

   inert 
  permanent 
  elements 
  and 
  the 
  heavier 
  and 
  shorter-lived 
  elements 
  

   of 
  the 
  stars. 
  

  

  An 
  interesting 
  question 
  is 
  whether 
  the 
  heavy 
  atoms 
  change 
  into 
  

   radiation 
  instantaneously, 
  or 
  only 
  through 
  successive 
  stages 
  of 
  trans- 
  

   formation. 
  Astronomical 
  evidence 
  makes 
  it 
  fairly 
  certain 
  that 
  the 
  

   most 
  massive 
  stars 
  contain 
  more 
  atoms 
  than 
  our 
  sun, 
  there 
  being 
  a 
  

   v/ider 
  range 
  in 
  the 
  weights 
  of 
  the 
  stars 
  than 
  in 
  the 
  atomic 
  weights 
  

   of 
  their 
  atoms. 
  As 
  these 
  stars 
  must 
  in 
  time 
  become 
  reduced 
  to 
  the 
  

   mass 
  of 
  our 
  sun, 
  the 
  process 
  of 
  evolution 
  clearly 
  calls 
  for 
  an 
  actual 
  

   annihilation 
  of 
  atoms; 
  it 
  is 
  not 
  enough 
  to 
  postulate 
  a 
  mere 
  gradual 
  

   decrease 
  in 
  the 
  atomic 
  weight 
  of 
  each 
  atom 
  until 
  it 
  ends 
  as 
  a 
  perma- 
  

   nent 
  atom. 
  Radioactivity 
  suggests 
  that 
  this 
  latter 
  process 
  may 
  also 
  

   occur, 
  but 
  the 
  evidence 
  of 
  astronomy 
  is 
  that 
  it 
  is 
  at 
  best 
  a 
  subsidiary 
  

   process. 
  

  

  The 
  number 
  of 
  " 
  permanent 
  " 
  atoms 
  in 
  a 
  massive 
  star 
  such 
  as 
  

   Antares 
  or 
  V 
  Puppis 
  can 
  not 
  undergo 
  any 
  perceptible 
  diminution 
  in 
  

   the 
  next 
  10'^ 
  years, 
  so 
  that 
  they 
  must 
  all 
  survive 
  in 
  the 
  final 
  star 
  of 
  

   mass 
  perhaps 
  only 
  a 
  fiftieth 
  of 
  that 
  of 
  the 
  present 
  star. 
  Thus 
  some 
  

   98 
  per 
  cent 
  of 
  the 
  present 
  masses 
  of 
  these 
  stars 
  must 
  consist 
  of 
  non- 
  

   permanent 
  atoms. 
  To 
  put 
  it 
  in 
  another 
  way, 
  the 
  present 
  mass 
  of 
  a 
  

   star 
  such 
  as 
  Antares 
  or 
  V 
  Puppis 
  must 
  consist, 
  as 
  regards 
  98 
  per 
  

   cent, 
  of 
  atoms 
  which 
  are 
  destined 
  to 
  change 
  into 
  radiation, 
  and 
  as 
  

   legards 
  only 
  2 
  per 
  cent, 
  of 
  atoms 
  which 
  can 
  not 
  change 
  into 
  radia- 
  

   tion. 
  Clearly 
  the 
  primary 
  matter 
  of 
  the 
  universe 
  must 
  be 
  of 
  non- 
  

   permanent 
  type; 
  our 
  terrestrial 
  atoms 
  are 
  a 
  mere 
  residue 
  of 
  non- 
  

   transformable 
  ashes. 
  Like 
  the 
  animalculse 
  of 
  the 
  raindrop 
  looking 
  

   out 
  on 
  to 
  Niagara, 
  we 
  discern 
  that 
  our 
  physics 
  and 
  chemistry 
  are 
  

   only 
  the 
  fringes 
  of 
  far-reaching 
  sciences; 
  beyond 
  the 
  seashore 
  we 
  

   have 
  explored 
  in 
  our 
  laboratories 
  lies 
  the 
  ocean 
  the 
  existence 
  of 
  

   which 
  we 
  are 
  only 
  just 
  beginning 
  to 
  suspect. 
  

  

  We 
  are 
  thus 
  led 
  to 
  picture 
  the 
  youngest 
  stars 
  as 
  formed 
  of 
  matter 
  

   practically 
  all 
  of 
  which 
  is 
  unknown 
  on 
  earth, 
  being 
  of 
  atomic 
  weight 
  

   higher 
  than 
  that 
  of 
  uranium. 
  This 
  possesses 
  the 
  capacity 
  of 
  annihi- 
  

  

  