APPENDIX 7 



REPORT ON THE ASTROPHYSICAL OBSERVATORY 



Sir : I have the honor to submit the following report on the activi- 

 ties of the Astrophysical Observatory for the fiscal year ended June 

 30, 1932: 



PLANT AND OBJECTS 



This observatory operates regularly the central station at Wash- 

 ington and two field stations for observing solar radiation on Table 

 Mountain, Calif., and Mount Montezuma, Chile. The station at 

 Mount Brukkaros, Southwest Africa, which was established by the 

 National Geographic Societ}^ and was continued for a time in co- 

 operation with the Astrophj^sical Observatory with funds donated 

 by a friend of the Institution, was closed in December, 1931.^ The 

 observatory controls a station on Mount Wilson, Calif., where occa- 

 sional expeditions are sent for special investigations, one of which 

 is mentioned below. 



The principal aim of the observatory is the exact measurement of, 

 the intensity of the radiation of the sun as it is at mean solar distance 

 outside the earth's atmosphere. This is ordinarily called the solar 

 constant of radiation, but the observations of past years by this 

 observatory have proved it variable. As all life, as well as the 

 weather, depends on solar radiation, the observatory has undertaken 

 the continued measurement of solar variation on all available days. 

 These measurements have now continued all the year round for 14 

 years. As will appear in this report, recent studies indicate that the 

 permanent continuation of these daily solar-radiation measurements 

 may have great value for weather forecasting. In addition to this 

 principal object, the observatory undertakes spectroscopic researches 

 on radiation and absorption of atmospheric constituents, radiation of 

 special substances, such as water vapor, ozone, carbonic-acid gas, 

 liquid water, and others, and the radiation of the other stars as well 

 as of the sun. 



WORK IN WASHINGTON 



Volume V of the Annals of the Observatory was printed and dis- 

 tributed in the autumn of 1931. It rehearses the aimals of the work 

 from 1920 to 1930 ; describes the stations and instruments employed ; 



1 The valuable collections of zoological and botanical specimens made in Southwest 

 Africa by Mrs. L. O. Sordahl, wife of the director, and brought back to Washington with 

 the instruments, are referred to above in the report of the National Museum. 



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