﻿COUNTING 
  THE 
  STARS 
  AND 
  SOME 
  CONCLUSIONS 
  

  

  By 
  Frederick 
  H. 
  Seares 
  

   Assistant 
  Director, 
  Mount 
  Wilson 
  Observatory, 
  Carnegie 
  Institution 
  of 
  Washington 
  

  

  [With 
  4 
  plates] 
  

  

  I 
  

  

  INTRODUCTION 
  

  

  Counting 
  stars 
  is 
  not 
  unlike 
  counting 
  people 
  or 
  sheep 
  or 
  pebbles 
  on 
  

   the 
  seashore. 
  The 
  astronomer's 
  difficulties 
  are 
  not 
  in 
  the 
  counting, 
  

   but 
  rather 
  in 
  knowing 
  when 
  the 
  counting 
  must 
  start 
  and 
  stop. 
  With 
  

   patience 
  these 
  difficulties 
  may 
  be 
  overcome, 
  but 
  the 
  conclusions 
  to 
  be 
  

   drawn 
  from 
  the 
  numbers 
  of 
  stars 
  counted 
  are 
  a 
  more 
  delicate 
  mat- 
  

   ter; 
  some 
  are 
  indisputable, 
  others 
  less 
  certain, 
  still 
  others 
  highly 
  

   speculative. 
  

  

  First 
  of 
  all, 
  we 
  are 
  concerned 
  with 
  a 
  census 
  of 
  the 
  sky; 
  and 
  just 
  as 
  

   the 
  census 
  taker 
  enumerates 
  people 
  in 
  different 
  ways 
  — 
  according 
  to 
  

   residence, 
  race, 
  occupation, 
  for 
  example 
  — 
  so 
  the 
  astronomer 
  may 
  

   count 
  his 
  stars 
  differently; 
  but, 
  whatever 
  the 
  manner 
  of 
  counting, 
  it 
  

   has 
  always 
  the 
  purpose 
  of 
  learning 
  how 
  the 
  stars 
  are 
  scattered 
  through- 
  

   out 
  space 
  and 
  how 
  the 
  great 
  system 
  which 
  they 
  form 
  is 
  constructed. 
  

  

  To 
  keep 
  clear 
  of 
  complexities 
  and 
  survey 
  only 
  the 
  broad 
  struc- 
  

   tural 
  features 
  of 
  the 
  system, 
  he 
  counts, 
  at 
  the 
  start, 
  in 
  only 
  two 
  ways; 
  

   to 
  learn 
  fundamental 
  things, 
  he 
  considers 
  characteristics 
  which 
  them- 
  

   selves 
  are 
  fundamentally 
  different. 
  At 
  first, 
  therefore, 
  he 
  observes 
  

   only 
  the 
  direction 
  of 
  a 
  star 
  in 
  the 
  sky 
  and 
  its 
  brightness 
  as 
  seen 
  with 
  

   the 
  telescope. 
  All 
  other 
  features 
  in 
  which 
  stars 
  differ, 
  such 
  as 
  size, 
  

   color, 
  mass, 
  motion, 
  are 
  left 
  for 
  subsequent 
  study. 
  It 
  is 
  as 
  though 
  

   the 
  census 
  taker 
  were 
  to 
  count 
  people 
  according 
  to 
  their 
  ages 
  and 
  the 
  

   places 
  in 
  which 
  they 
  live, 
  disregarding 
  all 
  other 
  possible 
  groupings, 
  

   such 
  as 
  height, 
  race, 
  and 
  occupation. 
  

  

  1 
  Reprinted 
  by 
  permission, 
  with 
  minor 
  changes, 
  from 
  Publications 
  of 
  the 
  Astronomical 
  Society 
  of 
  the 
  

   Pacific, 
  vol. 
  40, 
  pp. 
  303-331, 
  1928. 
  An 
  address 
  delivered 
  before 
  the 
  Pacific 
  Division 
  of 
  the 
  American 
  Asso- 
  

   ciation 
  for 
  the 
  Advancement 
  of 
  Science, 
  at 
  the 
  Pomona 
  meeting, 
  June 
  14, 
  1928. 
  A 
  detailed 
  account 
  of 
  the 
  

   investigations 
  here 
  described, 
  which 
  were 
  undertaken 
  in 
  part 
  with 
  the 
  cooperation 
  and 
  assistance 
  of 
  Prof. 
  

   P. 
  J. 
  van 
  Rhijn 
  of 
  the 
  Kapteyn 
  Astronomical 
  Laboratory 
  at 
  Groningen, 
  and 
  of 
  Miss 
  Mary 
  Joyner 
  and 
  

   Miss 
  Myrtle 
  Richmond 
  of 
  the 
  computing 
  division 
  of 
  the 
  Mount 
  WOson 
  Observatory, 
  may 
  be 
  found 
  in 
  Mt. 
  

   Wilson 
  Contributions, 
  Nos. 
  301, 
  346, 
  and 
  347. 
  

  

  183 
  

  

  