﻿UEPORT 
  OF 
  THE 
  SECRETARY 
  31 
  

  

  such 
  concessions 
  at 
  the 
  National 
  Zoo 
  would 
  not 
  only 
  provide 
  better 
  

   j-erA^ice 
  to 
  the 
  public 
  but 
  would 
  make 
  available 
  funds 
  for 
  the 
  purchase 
  

   of 
  new 
  specimens 
  for 
  the 
  exhibition 
  collection. 
  

  

  ASTROPHYSICAL 
  OBSERVATOEY 
  

  

  Work 
  at 
  Washington 
  included 
  preparations 
  for 
  an 
  attempt 
  to 
  

   improve 
  on 
  the 
  results 
  of 
  1923 
  in 
  measuring 
  the 
  energy-spectra 
  of 
  

   certain 
  stars. 
  Work 
  was 
  also 
  begun 
  on 
  a 
  new 
  type 
  of 
  pyrheliometer 
  

   for 
  the 
  solar 
  observations, 
  designed 
  to 
  still 
  further 
  reduce 
  errors. 
  

  

  The 
  important 
  work 
  of 
  revision 
  of 
  the 
  solar 
  radiation 
  measure- 
  

   ments 
  was 
  continued 
  vigorously 
  during 
  the 
  year. 
  The 
  records 
  from 
  

   the 
  Montezuma 
  station 
  from 
  1923 
  to 
  date 
  were 
  completely 
  re-reduced, 
  

   giving 
  values 
  which 
  may 
  now 
  be 
  considered 
  definitive. 
  The 
  obser- 
  

   vations 
  from 
  the 
  Table 
  Mountain 
  station 
  are 
  being 
  similarly 
  treated, 
  

   and 
  when 
  completed 
  will 
  permit 
  of 
  the 
  publication 
  of 
  definitive 
  

   values 
  from 
  that 
  station 
  also. 
  

  

  The 
  observing 
  station 
  at 
  Table 
  Mountain, 
  Calif,, 
  which 
  replaces 
  

   that 
  formerly 
  occupied 
  at 
  Mount 
  Harqua 
  Hala, 
  Ariz., 
  has 
  been 
  in 
  

   continuous 
  operation 
  throughout 
  the 
  year. 
  Although 
  the 
  number 
  

   of 
  days 
  on 
  which 
  solar 
  observations 
  may 
  be 
  made 
  does 
  not 
  greatly 
  

   exceed 
  that 
  at 
  Harqua 
  Hala, 
  the 
  quality 
  of 
  those 
  days 
  for 
  observing, 
  

   especially 
  from 
  June 
  to 
  September, 
  is 
  vastly 
  superior. 
  The 
  daily 
  

   results 
  from 
  the 
  Montezuma, 
  Chile, 
  station 
  have 
  been 
  published 
  on 
  

   the 
  United 
  States 
  weather 
  maps 
  of 
  the 
  day 
  following. 
  They 
  have 
  

   also 
  been 
  transmitted 
  daily 
  by 
  telegraph 
  to 
  the 
  Argentine 
  Govern- 
  

   ment 
  and 
  to 
  the 
  publisher 
  of 
  a 
  monthl}^ 
  meteorological 
  bulletin 
  con- 
  

   taining 
  them. 
  The 
  station 
  on 
  Mount 
  Brukkaros, 
  South 
  West 
  Africa, 
  

   built 
  and 
  maintained 
  for 
  the 
  Institution 
  by 
  the 
  National 
  Geographic 
  

   Society, 
  began 
  daily 
  observations 
  under 
  the 
  direction 
  of 
  Mr. 
  W. 
  H. 
  

   Hoover, 
  director, 
  in 
  December, 
  1926. 
  It 
  is 
  too 
  soon 
  to 
  decide 
  how 
  

   favorable 
  the 
  atmospheric 
  conditions 
  at 
  this 
  new 
  station 
  will 
  be. 
  

   For 
  a 
  considerable 
  part 
  of 
  the 
  time 
  they 
  have 
  been 
  first 
  class, 
  and 
  

   what 
  unfavorable 
  weather 
  has 
  been 
  experienced, 
  according 
  to 
  old 
  

   residents 
  of 
  the 
  region, 
  has 
  been 
  unusual. 
  

  

  Correlations 
  of 
  the 
  variation 
  in 
  solar 
  radiation 
  with 
  other 
  results 
  

   have 
  appeared 
  during 
  the 
  year. 
  Doctor 
  Pettit's 
  observations 
  of 
  

   ultra-violet 
  solar 
  radiation 
  are 
  closely 
  in 
  proportion 
  with 
  the 
  changes 
  

   found 
  in 
  total 
  solar 
  radiation 
  by 
  the 
  Smithsonian 
  observers. 
  Doctor 
  

   Austin 
  has 
  found 
  a 
  very 
  high 
  correlation 
  between 
  changes 
  in 
  the 
  

   solar 
  constant 
  and 
  long-range 
  radio 
  reception. 
  

  

  Doctor 
  Abbot 
  has 
  found 
  a 
  remarkable 
  regular 
  periodicity 
  of 
  

   25% 
  months 
  in 
  the 
  solar 
  variation 
  itself, 
  which, 
  with 
  the 
  sun-spot 
  

   cycle, 
  accounts 
  for 
  almost 
  the 
  Avhole 
  change 
  in 
  monthly 
  mean 
  solar 
  

  

  