﻿174 
  

  

  ANNUAL 
  EEPOET 
  SMITHSONIAN 
  INSTITUTION, 
  192 
  9 
  

  

  the 
  temperature 
  at 
  which 
  bombardment 
  by 
  electrons, 
  nuclei, 
  or 
  mole- 
  

   cules 
  would 
  first 
  begin 
  to 
  be 
  effective 
  is 
  precisely 
  the 
  same 
  as 
  that 
  at 
  

   which 
  radiation 
  of 
  the 
  effective 
  wave 
  length 
  would 
  first 
  begin 
  to 
  be 
  

   appreciable; 
  the 
  two 
  processes 
  begin 
  at 
  the 
  same 
  temperature. 
  

  

  Table 
  III. 
  — 
  The 
  mechanical 
  effects 
  of 
  radiation 
  

  

  Wave 
  lengths 
  (cm.) 
  

  

  Nature 
  of 
  

   radiation 
  

  

  Effect 
  on 
  atom 
  

  

  Temperature 
  (degrees 
  

   abs.) 
  

  

  Where 
  found 
  

  

  7,500X10-8 
  to 
  3,750X10-s 
  

  

  250X10-8 
  to 
  10-8 
  

  

  5X10-»tolO-9 
  

  

  4X10-10 
  

  

  5X10-11 
  

  

  4.5X10-12 
  

  

  2X10-121 
  

  

  1.3X10-13 
  

  

  visible 
  light. 
  

  

  X 
  rays 
  

  

  Soft 
  y 
  rays.. 
  

  

  7 
  rays 
  of 
  ra- 
  

   dium-J3. 
  

  

  Hardest 
  y 
  

   rays. 
  

  

  (?)— 
  

  

  Disturbs 
  outermost 
  

   electrons. 
  

  

  Disturbs 
  inner 
  elec- 
  

   trons. 
  

  

  Strip 
  off 
  all 
  or 
  nearly 
  

   all 
  electrons. 
  

  

  Disturbs 
  nuclear 
  ar- 
  

   rangement. 
  

  

  Highly-pene- 
  

   trating 
  ra- 
  

   diation. 
  

  

  (?) 
  

  

  Buildmg 
  of 
  helium 
  

   atom 
  out 
  of 
  hydro- 
  

   gen. 
  

  

  D 
  isintegrates 
  nuclei 
  . 
  

  

  Annihilation 
  or 
  crea- 
  

   tion 
  of 
  proton 
  and 
  

   accompanying 
  elec- 
  

   tron. 
  

  

  3,850 
  to 
  7,700 
  

  

  115,000 
  to 
  29,000,000 
  

  

  58,000,000 
  to 
  290,000,000 
  

  

  720,000,000 
  

  

  5,800,000,000 
  

  

  64,000,000,000 
  - 
  

  

  150,000,000,000 
  

  

  2,^00,000,000,000 
  

  

  Stellar 
  atmos- 
  

   pheres. 
  

   Stellar 
  interiors. 
  

  

  Central 
  regions 
  

   of 
  dense 
  stars. 
  

   (?). 
  

  

  1 
  See 
  added 
  item 
  on 
  p. 
  179. 
  

  

  We 
  have 
  seen, 
  then, 
  that 
  the 
  apparent 
  difference 
  between 
  the 
  behav- 
  

   ior 
  of 
  the 
  calcium 
  atom 
  and 
  of 
  the 
  uranium 
  nucleus 
  reduces, 
  in 
  theory, 
  

   to 
  a 
  mere 
  difference 
  of 
  temperature, 
  although 
  in 
  practice 
  the 
  difference 
  

   is 
  all 
  the 
  difference 
  between 
  5,000° 
  and 
  5,000,000,000°. 
  The 
  lower 
  

   temperature 
  is 
  approached 
  or 
  exceeded 
  in 
  the 
  atmospheres 
  of 
  most 
  

   stars, 
  so 
  that 
  the 
  calcium 
  atom 
  is 
  continually 
  rearranging 
  itself 
  in 
  

   these 
  atmospheres, 
  as 
  is 
  shown 
  by 
  the 
  presence 
  of 
  the 
  H 
  and 
  K 
  lines 
  

   of 
  calcium 
  in 
  most 
  stellar 
  spectra. 
  It 
  is 
  unlikely 
  that 
  the 
  higher 
  tem- 
  

   perature 
  is 
  approached 
  anywhere 
  in 
  the 
  universe, 
  although 
  exceptions, 
  

   arising 
  from 
  our 
  ignorance 
  rather 
  than 
  our 
  knowledge, 
  must 
  possibly 
  

   be 
  made 
  in 
  favor 
  of 
  the 
  centers 
  of 
  certain 
  "white-dwarf" 
  stars 
  and 
  

   of 
  the 
  spiral 
  nebulae. 
  Apart 
  from 
  these, 
  no 
  place 
  is 
  known 
  hot 
  enough 
  

   to 
  have 
  any 
  appreciable 
  effect 
  on 
  the 
  transformation, 
  either 
  by 
  syn- 
  

   thesis 
  or 
  by 
  disintegration, 
  of 
  the 
  radioactive 
  elements, 
  and 
  we 
  must 
  

   conclude 
  that 
  they 
  behave 
  everywhere 
  in 
  the 
  same 
  spontaneous 
  fatal- 
  

   istic 
  way 
  that 
  they 
  do 
  on 
  earth; 
  nowhere 
  is 
  there 
  sufficiently 
  intense 
  

   heat 
  to 
  cause 
  them 
  to 
  vary 
  their 
  conduct. 
  

  

  Thus 
  solar 
  uranium, 
  which, 
  as 
  we 
  have 
  already 
  seen, 
  must 
  have 
  been 
  

   born 
  in 
  the 
  sun, 
  can 
  scarcely 
  have 
  been 
  born 
  out 
  of 
  the 
  synthesis 
  of 
  

   lighter 
  elements, 
  and 
  so 
  must 
  have 
  originated 
  out 
  of 
  the 
  disintegration 
  

   of 
  heavier 
  elements. 
  The 
  position 
  with 
  respect 
  to 
  solar 
  uranium 
  is 
  

   precisely 
  analogous 
  to 
  that 
  we 
  have 
  already 
  reached 
  in 
  respect 
  of 
  

   terrestrial 
  radium, 
  but 
  there 
  is 
  the 
  outstanding 
  difference 
  that 
  we 
  

  

  