APPENDIX 7. 

 REPORT ON THE ASTROPHYSICAL OBSERVATORY. 



Sir : The Astrophysical Observatory was conducted under the fol- 

 lowing passage of the sundry civil act, approved June 5, 1919 : 



Astrophysical Observatory: For maintenance of the Astrophysical Observa- 

 tory, under the direction of the Smithsonian Institution, including assistants, 

 purchase of necessary books and periodicals, apparatus, making necessary ob- 

 servations in high altitudes, repairs and alterations of buildings, and miscel- 

 laneous expenses, $13,000. 



The observatory occupies a number of frame structures within an 

 inclosure of about 16,000 square feet south of the Smithsonian admin- 

 istration building at Washington, and also a cement observing station 

 and frame cottage for observers on a plot of 10,000 square feet leased 

 from the Carnegie Solar Observatory, on Mount Wilson, Calif. 



A new solar observing station was erected in July, 1920, at the ex- 

 pense of funds donated for the purpose by Mr. John A. Roebling, of 

 Bernardsville, N. J., and this station has been occupied as a solar 

 radiation observing station by the Astrophysical Observatory since 

 October, 1920. 



The present value of the buildings and equipment for the Astro- 

 physical Observatory owned by the Government is estimated at 

 $50,000. This estimate contemplates the cost required to replace the 

 outfit for the purposes of the investigation. 



WORK OF THE YEAR. 



At Washington.— -The preparation of the manuscript for Volume 

 IV of the Annals of the Observatory was continued. Owing to the 

 postponement of its publication, it has required to be brought up to 

 date by repeated additions and modifications, and it is now expected 

 to publish in Volume IV all the results up to September, 1920, when 

 the solar radiation apparatus which had been employed on Mount 

 Wilson was removed to Mount Harqua Hala, Ariz. A great deal of 

 measuring and computing was required to bring up to date the work 

 of 1919 and 1920 on the solar constant of radiation and to work up 

 the results of the observations of the distribution of light over the 

 sun's disk, which have been carried on since 1916 with only partial 

 reduction. This work went on under Mr. Fowle's direction, assisted 

 by Mrs. Bond, computer, and for a few months by temporary com- 

 puters, Miss Inez Ensign and Miss Esther Weaver. The cost of em- 



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