﻿616 
  F. 
  W. 
  Very 
  — 
  /Solar 
  ^Radiation. 
  

  

  supposed 
  to 
  exhibit 
  a 
  law 
  of 
  change 
  opposite 
  to 
  that 
  of 
  the 
  

   sun 
  : 
  " 
  Mira 
  increases 
  in 
  brightness 
  faster 
  than 
  it 
  decreases." 
  

   The 
  discrepancy, 
  however, 
  arises 
  from 
  what 
  I 
  believe 
  to 
  be 
  a 
  

   mistaken 
  conclusion 
  in 
  regard 
  to 
  the 
  variation 
  of 
  terrestrial 
  

   temperatures 
  attributable 
  to 
  solar 
  changes. 
  In 
  my 
  paper 
  on 
  

   " 
  The 
  Variation 
  of 
  Solar 
  Radiation," 
  I 
  concluded 
  that 
  " 
  the 
  

   maximum 
  temperatures 
  are 
  higher 
  for 
  a 
  time 
  of 
  many 
  sun- 
  

   spots 
  in 
  the 
  torrid 
  zone, 
  and 
  lower 
  in 
  the 
  temperate 
  zone."* 
  

   The 
  cause 
  of 
  hesitation 
  in 
  the 
  acceptance 
  of 
  this 
  conclusion 
  is 
  

   also 
  pointed 
  out 
  : 
  " 
  Most 
  of 
  our 
  material 
  comes 
  from 
  the 
  

   temperate 
  zones 
  and 
  is 
  difficult 
  to 
  analyze. 
  The 
  fact 
  that 
  so 
  

   large 
  a 
  part 
  of 
  the 
  earth 
  is 
  in 
  lower 
  latitudes 
  than 
  the 
  average 
  

   storm-belts, 
  and 
  that 
  the 
  greater 
  part 
  of 
  this 
  surface 
  is 
  oceanic, 
  

   warns 
  us 
  that 
  our 
  mid-latitude 
  storms 
  are 
  a 
  mere 
  fringe 
  on 
  

   the 
  grander 
  field 
  of 
  tropical 
  atmospheric 
  activities. 
  "f 
  " 
  It 
  does 
  

   not 
  appear 
  to 
  be 
  necessary 
  that 
  the 
  sign 
  of 
  such 
  temperate 
  

   residual 
  should 
  agree 
  with 
  that 
  from 
  the 
  tropics. 
  While 
  

   higher 
  tropical 
  temperature 
  produced 
  by 
  greater 
  solar 
  radia- 
  

   tion 
  must 
  increase 
  convection, 
  which 
  may 
  transfer 
  extra 
  heat 
  

   to 
  the 
  temperate 
  and 
  polar 
  zones, 
  it 
  is 
  quite 
  possible 
  that 
  cer- 
  

   tain 
  regions 
  may 
  get 
  more 
  than 
  their 
  share 
  of 
  the 
  returning 
  

   polar 
  winds 
  concerned 
  in 
  the 
  convection, 
  and 
  may 
  have 
  their 
  

   temperature 
  lowered 
  thereby. 
  This, 
  in 
  fact, 
  appears 
  to 
  be 
  the 
  

   case 
  in 
  the 
  upper 
  Mississippi 
  valley 
  and 
  in 
  Europe."^ 
  

  

  The 
  prevalent 
  scientific 
  opinion 
  that 
  the 
  earth 
  is 
  cooler 
  at 
  

   sun-spot 
  maximum 
  is, 
  I 
  believe, 
  contrary 
  to 
  fact, 
  and 
  has 
  

   apparently 
  arisen 
  because 
  most 
  of 
  the 
  people 
  who 
  hold 
  this 
  

   opinion 
  reside 
  in 
  the 
  region 
  of 
  " 
  the 
  returning 
  polar 
  winds 
  

   concerned 
  in 
  the 
  convection." 
  Mr. 
  Henry 
  F. 
  Blanford, 
  than 
  

   whom 
  there 
  has 
  been 
  no 
  more 
  competent 
  student 
  of 
  the 
  mete- 
  

   orology 
  of 
  the 
  torrid 
  zone, 
  says 
  in 
  his 
  " 
  Indian 
  Meteorologists' 
  

   Yade-mecum 
  "§ 
  that 
  " 
  the 
  solar 
  radiation 
  is 
  greatest 
  in 
  years 
  

   of 
  abundant 
  sun-spots 
  and 
  vice 
  versa. 
  . 
  . 
  . 
  The 
  results 
  of 
  

   eleven 
  stations, 
  in 
  different 
  parts 
  of 
  India, 
  showed 
  an 
  increase 
  

   of 
  at 
  least 
  6° 
  in 
  the 
  mean 
  equilibrium 
  temperature 
  of 
  solar 
  

   radiation 
  at 
  the 
  earth's 
  surface 
  between 
  1868 
  and 
  1871 
  (the 
  

   last 
  following 
  a 
  year 
  of 
  maximum 
  sun-spots) 
  ; 
  and 
  this, 
  I 
  am 
  

   inclined 
  to 
  think, 
  is 
  in 
  defect 
  of 
  the 
  truth. 
  The 
  variation 
  is 
  

   thus 
  by 
  no 
  means 
  inconsiderable." 
  

  

  In 
  explanation 
  of 
  the 
  discrepancy 
  between 
  his 
  results 
  and 
  

   those 
  of 
  Koppen, 
  Blanford 
  says 
  : 
  " 
  The 
  temperatures 
  dealt 
  

   with 
  by 
  Professor 
  Koppen 
  are, 
  of 
  course, 
  those 
  of 
  the 
  lowest 
  

   stratum 
  of 
  the 
  atmosphere 
  as 
  observed 
  at 
  land 
  stations, 
  and 
  

   must 
  be 
  determined, 
  not 
  by 
  the 
  quantity 
  of 
  heat 
  that 
  falls 
  on 
  

  

  * 
  Astrophysical 
  Journal, 
  vol. 
  vii, 
  p. 
  255, 
  April, 
  1898. 
  

   + 
  Op. 
  cit., 
  p. 
  263. 
  

   % 
  Op. 
  cit. 
  , 
  p. 
  264-5. 
  

   §P. 
  159. 
  

  

  