﻿632 
  F. 
  W. 
  Very 
  — 
  Solar 
  Radiation. 
  

  

  temperature 
  from 
  the 
  normal 
  on 
  any 
  one 
  day 
  over 
  all 
  points 
  

   of 
  the 
  globe, 
  and 
  form 
  their 
  mean. 
  The 
  fluctuations 
  of 
  this 
  

   mean 
  would 
  represent 
  those 
  of 
  the 
  sun's 
  radiation" 
  (p. 
  314). 
  

   Of 
  two 
  regions, 
  A 
  and 
  B, 
  " 
  if 
  we 
  found 
  that 
  the 
  mean 
  tempera- 
  

   ture 
  at 
  B 
  was 
  above 
  normal 
  when 
  it 
  was 
  above 
  the 
  normal 
  in 
  A, 
  

   and 
  below 
  it 
  in 
  the 
  contrary 
  case, 
  it 
  would 
  show 
  that 
  there 
  was 
  

   some 
  common 
  cause 
  affecting 
  the 
  two 
  places. 
  Should 
  the 
  mean 
  

   temperature 
  in 
  B 
  be 
  entirely 
  independent 
  of 
  A 
  it 
  would 
  show 
  

   that 
  there 
  was 
  no 
  common 
  cause 
  affecting 
  the 
  temperature 
  of 
  

   the 
  two 
  places 
  and 
  therefore 
  that 
  the 
  fluctuations 
  were 
  not 
  due 
  to 
  

   changes 
  in 
  the 
  sun's 
  radiation" 
  (p. 
  315 
  ). 
  

  

  These 
  are 
  extraordinary 
  principles 
  to 
  adopt 
  as 
  the 
  basis 
  for 
  

   discovering 
  changes 
  in 
  the 
  solar 
  radiation. 
  One 
  might 
  as 
  reason- 
  

   ably 
  anticipate 
  a 
  simultaneous 
  high 
  tide 
  over 
  all 
  the 
  earth 
  as 
  to 
  

   "expect 
  a 
  similar 
  change 
  in 
  every 
  other 
  region 
  " 
  if 
  a 
  particular 
  

   climatic 
  effect 
  in 
  some 
  one 
  region 
  is 
  attributable 
  to 
  a 
  variation 
  

   in 
  solar 
  radiation. 
  Climatic 
  phenomena 
  are 
  seldom 
  regulated 
  in 
  

   such 
  a 
  simple 
  and 
  direct 
  way, 
  but 
  a 
  given 
  change 
  in 
  one 
  part 
  

   of 
  the 
  earth, 
  even 
  if 
  caused 
  by 
  an 
  increase 
  or 
  decrease 
  of 
  solar 
  

   radiation, 
  will 
  set 
  in 
  action 
  a 
  long 
  train 
  of 
  consequences 
  and 
  

   will 
  be 
  accompanied 
  by 
  an 
  opposite 
  change 
  somewhere 
  else, 
  

   while 
  between 
  the 
  localities 
  of 
  opposing 
  effects 
  lie 
  apparently 
  

   neutral 
  belts 
  of 
  conflicting 
  phases. 
  

  

  In 
  comparing 
  solar 
  effects 
  for 
  different 
  localities 
  we 
  must 
  first 
  

   be 
  sure 
  that 
  the 
  phases 
  are 
  the 
  same, 
  otherwise 
  the 
  signs 
  should 
  

   be 
  changed 
  for 
  the 
  region 
  of 
  inverted 
  type. 
  Next 
  we 
  must 
  

   recognize 
  that, 
  while 
  types 
  may 
  persist 
  over 
  extensive 
  areas 
  

   of 
  the 
  earth's 
  surface, 
  there 
  are 
  intermediate 
  regions 
  in 
  which 
  

   the 
  type 
  varies 
  through 
  shifting 
  of 
  the 
  great 
  centers 
  of 
  action 
  

   which 
  govern 
  world-wide 
  circulatory 
  phenomena 
  of 
  the 
  atmos- 
  

   phere. 
  Any 
  lag 
  in 
  the 
  phase 
  will 
  require 
  a 
  time-adjustment 
  

   before 
  the 
  waves 
  for 
  different 
  locations 
  can 
  be 
  compared. 
  

   Finally, 
  it 
  is 
  probably 
  a 
  mistake 
  to 
  assume 
  that 
  the 
  solar 
  radi- 
  

   ant 
  changes 
  can 
  be 
  represented 
  by 
  a 
  simple 
  sinusoid 
  curve, 
  as 
  

   though 
  they 
  were 
  regular 
  like 
  the 
  planetary 
  revolutions. 
  On 
  

   the 
  contrary, 
  the 
  solar 
  changes 
  are 
  only 
  approximately 
  periodic, 
  

   and 
  several 
  different 
  periods, 
  each 
  of 
  slightly 
  varying 
  duration, 
  

   are 
  superposed. 
  Even 
  harmonic 
  analysis, 
  which 
  deals 
  success- 
  

   fully 
  with 
  simultaneous 
  sinusoid 
  phases 
  of 
  various 
  periods, 
  is 
  

   nonplussed 
  by 
  such 
  a 
  complex. 
  

  

  Newcomb's 
  rigid 
  criterion 
  starts 
  with 
  an 
  erroneous 
  hypoth- 
  

   esis. 
  The 
  criterion 
  has 
  been 
  invented 
  to 
  get 
  rid 
  of 
  the 
  acci- 
  

   dental 
  fluctuations, 
  which 
  it 
  does, 
  but 
  at 
  the 
  same 
  time 
  it 
  also 
  

   eliminates 
  the 
  solar 
  radiant 
  phases 
  which 
  it 
  is 
  proposed 
  to 
  

   investigate. 
  No 
  other 
  outcome 
  than 
  a 
  purely 
  negative 
  one 
  

   was 
  to 
  be 
  anticipated. 
  It 
  was 
  principally 
  to 
  meet 
  the 
  special 
  

   case 
  of 
  a 
  j)eriodicity 
  of 
  varying 
  length 
  that 
  Newcomb 
  devised 
  

   his 
  " 
  criterion 
  for 
  distinguishing 
  between 
  a 
  definite 
  period 
  

  

  