﻿F. 
  W. 
  Very— 
  Solar 
  Radiation. 
  633 
  

  

  [even 
  though 
  this 
  be 
  of 
  fluctuating 
  length] 
  and 
  complete 
  

   irregularity," 
  always, 
  however, 
  subject 
  to 
  the 
  supposition 
  that 
  

   there 
  is 
  no 
  question 
  in 
  regard 
  to 
  the 
  identification 
  of 
  max- 
  

   imum 
  and 
  minimum 
  in 
  the 
  phase, 
  but 
  that 
  the 
  maxima, 
  or 
  

   positive 
  departures 
  in 
  surface 
  temperature 
  due 
  to 
  variation 
  of 
  

   solar 
  radiation, 
  will 
  everywhere 
  coincide. 
  This 
  is 
  the 
  funda- 
  

   mental 
  error 
  which 
  overthrows 
  the 
  final 
  conclusion. 
  There 
  may 
  

   be 
  provision 
  for 
  detecting 
  a 
  slight 
  lag, 
  but 
  there 
  is 
  none 
  for 
  deal- 
  

   ing 
  with 
  a 
  complete 
  reversal 
  of 
  phase. 
  If, 
  however, 
  instead 
  of 
  

   attempting 
  to 
  apply 
  his 
  criterion 
  to 
  the 
  whole 
  world, 
  Newcomb 
  

   had 
  tried 
  it 
  on 
  a 
  single 
  homogeneous 
  region 
  of 
  one 
  common 
  type, 
  

   he 
  would 
  not 
  have 
  cancelled 
  out 
  his 
  opposing 
  phases. 
  Bigelow* 
  

   has 
  used 
  the 
  method 
  for 
  a 
  particular 
  region 
  where 
  the 
  solar 
  

   radiant 
  impulses 
  give 
  rise 
  to 
  a 
  climatic 
  effect 
  of 
  a 
  single 
  type 
  

   throughout 
  the 
  area, 
  and 
  finds 
  conclusive 
  evidence 
  of 
  a 
  true 
  

   solar 
  periodicity, 
  which 
  leads 
  him 
  to 
  remark 
  that 
  Newcornb 
  

   has 
  not 
  done 
  full 
  justice 
  to 
  his 
  criterion. 
  When 
  two 
  different 
  

   phenomena 
  are 
  related 
  simply 
  by 
  coincidence 
  of 
  a 
  maximum, 
  it 
  

   takes 
  a 
  great 
  many 
  recurrences 
  to 
  completely 
  establish 
  the 
  con- 
  

   nection 
  ; 
  but 
  where 
  the 
  relation 
  includes 
  further 
  details 
  in 
  

   respect 
  to 
  congruous 
  curves, 
  this 
  is 
  equivalent 
  to 
  an 
  indefinite 
  

   multiplication 
  of 
  coincidences 
  and 
  the 
  relation 
  may 
  be 
  discerned 
  

   from 
  comparatively 
  few 
  observations. 
  

  

  Criteria 
  are 
  also 
  needed 
  in 
  other 
  departments 
  of 
  solar 
  radia- 
  

   tion 
  study 
  to 
  decide 
  upon 
  the 
  permissible 
  limits 
  of 
  deduction. 
  

   Questions 
  have 
  arisen 
  as 
  to 
  the 
  proper 
  times 
  and 
  stations 
  for 
  

   actinometric 
  measurements 
  which 
  can 
  be 
  settled 
  in 
  no 
  other 
  

   way 
  than 
  by 
  means 
  of 
  decisive 
  criteria 
  or 
  crucial 
  tests. 
  The 
  

   Smithsonian 
  observations, 
  for 
  example, 
  usually 
  stop 
  when 
  the 
  

   air 
  mass 
  becomes 
  as 
  large 
  as 
  3 
  or 
  4 
  atmospheres. 
  Some 
  do 
  not 
  

   even 
  extend 
  to 
  2 
  atmospheres. 
  Reduced 
  by 
  Bouguer's 
  for- 
  

   mula, 
  these 
  midday 
  readings 
  agree 
  among 
  themselves, 
  but 
  

   solely 
  because 
  they 
  have 
  stopped 
  before 
  reaching 
  the 
  point 
  

   where 
  disagreement 
  begins. 
  This 
  is 
  equivalent 
  to 
  shirking 
  the 
  

   difficulties, 
  and 
  the 
  seeming 
  extraordinary 
  agreement 
  of 
  the 
  

   measures 
  is 
  misleading. 
  If 
  the 
  missing 
  readings 
  had 
  been 
  

   supplied, 
  the 
  discrepancies 
  would 
  have 
  been 
  obvious.f 
  Such 
  

  

  * 
  Frank 
  H. 
  Bigelow 
  : 
  " 
  Studies 
  in 
  the 
  General 
  Circulation 
  of 
  the 
  Earth's 
  

   Atmosphere," 
  this 
  Journal 
  (4), 
  vol. 
  xxix, 
  p. 
  277, 
  April, 
  1910. 
  

  

  fin 
  Abbot's 
  work 
  on 
  "The 
  Sun," 
  in 
  the 
  pages 
  devoted 
  to 
  the 
  solar 
  con- 
  

   stant, 
  one 
  looks 
  in 
  vain 
  for 
  even 
  the 
  bare 
  mention 
  of 
  the 
  names 
  of 
  Forbes, 
  

   Violle, 
  Crova, 
  Langley, 
  Hanski, 
  Savelief 
  and 
  many 
  others 
  whose 
  work 
  has 
  

   helped 
  to 
  solve 
  this 
  greatest 
  of 
  astrophysical 
  problems. 
  The 
  only 
  name 
  

   mentioned 
  by 
  Mr. 
  Abbot 
  in 
  this 
  connection 
  is 
  that 
  of 
  Pouillet, 
  whose 
  results 
  

   resemble 
  his 
  own, 
  while 
  those 
  passed 
  by 
  in 
  silence 
  totally 
  disagree. 
  

  

  It 
  is 
  not 
  always 
  possible 
  to 
  secure 
  complete 
  series 
  of 
  actinometric 
  observa- 
  

   tions, 
  but 
  this 
  does 
  not 
  absolve 
  us 
  from 
  the 
  duty 
  of 
  trying 
  to 
  make 
  them. 
  

   The 
  fine 
  work 
  of 
  Mr. 
  H. 
  H. 
  Kimball, 
  who, 
  on 
  several 
  occasions, 
  has 
  followed 
  

   the 
  snn 
  almost 
  or 
  quite 
  to 
  its 
  setting, 
  and 
  whose 
  actinometric 
  measurements 
  

   have 
  been 
  of 
  great 
  assistance 
  to 
  me, 
  deserves 
  especial 
  mention 
  by 
  way 
  of 
  

   contrast, 
  and 
  the 
  splendid 
  services 
  of 
  M. 
  Crova 
  to 
  this 
  study 
  will 
  never 
  be 
  

   forgotten. 
  

  

  