﻿EEPOET 
  OF 
  THE 
  SECRETARY 
  113 
  

  

  Field 
  assistant, 
  Mr. 
  F. 
  A. 
  Greeley, 
  Mount 
  Brukkaros. 
  

   Computer, 
  Mrs. 
  A. 
  M. 
  Bond, 
  Washington. 
  

   Computer, 
  Miss 
  M. 
  A. 
  Maesden, 
  Washington. 
  

   Computer,^ 
  Miss 
  M. 
  C. 
  Rhoderick, 
  Washington 
  (temporary). 
  

   Instrument 
  maker, 
  Mr. 
  A. 
  Kramer, 
  Washington. 
  

   Librarian,' 
  Mrs. 
  M. 
  L. 
  Reed, 
  Washington 
  (temporary). 
  

   Librarian^' 
  Mrs. 
  A. 
  E. 
  Blanchajkd, 
  Washington 
  (temporary). 
  

   Librarian,' 
  Miss 
  M. 
  B. 
  Ladd, 
  Washington 
  (temporary). 
  

   Librarian,^ 
  Miss 
  C. 
  S. 
  Gunther, 
  Washington 
  (temporary). 
  

  

  Swrwiary. 
  — 
  The 
  work 
  of 
  the 
  year 
  was 
  mainly 
  in 
  continuation 
  of 
  

   accurate 
  observations 
  of 
  the 
  solar 
  constant 
  of 
  radiation. 
  A 
  new 
  

   cooperating 
  observatory 
  in 
  South 
  West 
  Africa 
  was 
  installed 
  at 
  the 
  

   cost 
  of 
  the 
  National 
  Geographic 
  Society. 
  Improved 
  apparatus 
  and 
  

   procedure 
  has 
  led 
  to 
  a 
  higher 
  standard 
  of 
  accuracy 
  in 
  all 
  the 
  observa- 
  

   tories 
  than 
  ever 
  before. 
  

  

  Gratifying 
  correlations 
  with 
  other 
  results 
  are 
  appearing. 
  Thus 
  

   Doctor 
  Pettit's 
  observations 
  of 
  ultra-violet 
  solar 
  radiation, 
  while 
  

   showing 
  extreme 
  variations 
  of 
  at 
  least 
  a 
  hundred 
  per 
  cent, 
  are 
  

   closely 
  in 
  proportion 
  with 
  the 
  small 
  changes 
  found 
  in 
  total 
  solar 
  

   radiation 
  by 
  the 
  Smithsonian 
  observers. 
  Doctor 
  Austin, 
  too, 
  finds 
  a 
  

   very 
  high 
  correlation 
  between 
  solar 
  constant 
  changes 
  and 
  the 
  recep- 
  

   tion 
  of 
  long 
  range 
  radio. 
  

  

  Finallj'', 
  a 
  remarkable 
  regular 
  periodicity 
  of 
  25% 
  months 
  has 
  been 
  

   found 
  by 
  Dr. 
  C. 
  G. 
  Abbot 
  in 
  the 
  solar 
  variation 
  itself, 
  which, 
  

   during 
  the 
  years 
  1920 
  to 
  1927, 
  has 
  joined 
  with 
  the 
  sun-spot 
  cycle 
  to 
  

   account 
  for 
  almost 
  the 
  whole 
  change 
  in 
  monthly 
  mean 
  solar 
  constant 
  

   results. 
  If 
  this 
  persists 
  in 
  future 
  years, 
  it 
  may 
  become 
  possible 
  to 
  

   forecast 
  at 
  least 
  two 
  years 
  in 
  advance 
  the 
  principal 
  solar 
  changes, 
  

   and 
  whatever 
  of 
  importance 
  may 
  prove 
  to 
  hang 
  thereon. 
  

  

  Respectfully 
  submitted. 
  

  

  C. 
  G. 
  Abbot, 
  

   Director^ 
  Asti^o 
  physical 
  Observatory. 
  

  

  To 
  the 
  Acting 
  Secretary, 
  

  

  Smithsonian 
  Institution. 
  

  

  * 
  This 
  compensation 
  was 
  defrayed 
  in 
  part 
  or 
  wholly 
  from 
  private 
  funds. 
  

  

  