APPENDIX 7 

 KEPORT ON THE ASTROPHYSICAL OBSERVATORY 



SiK : The Astrophysical Observatory was conducted under the fol- 

 lowing passage of the independent offices appropriation act approved 

 February 13, 1923 : 



Astrophysical Observatoi-y : 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 

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

 laneous expenses, $15,500. 



The observatory occupies a number of frame structures within an 

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

 ministration 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 on Mount Harqua Hala, Ariz., was 

 erected in July, 1920, at the expense of funds donated for the pur- 

 pose by Mr. John A, Roebling, of Bernardsville, N. J., and this sta- 

 tion has been occupied as a solar radiation observing station by the 

 Astrophysical Observatory since October, 1920. 



The i)resent 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 

 outiit for the purposes of the investigation. 



WORK OF THE YEAR 



There have been several features of particular interest, including 

 the installation of daily telegraphic reports from the Arizona and 

 Chile solar-radiation stations, certain experimental forecasts based 

 on these reports, and the measurement of the energy distribution in 

 the spectra of 10 of the brighter stars. 



Work at W ashington. — As in previous years, the variation of the 

 sun has been the main concern. The generosity of Mr. John A. 

 Roebling enabled arrangements to be made for daily telegrams from 

 our two solar radiation stations. This service was begun September 

 13, 1923. The results obtained in Chile are cabled in code, so that the 

 Aveighted mean solar-constant value, the date and hour of observa- 



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