Appendix V. 



REPORT ON THE ASTROPHYSICAL OBSERVATORY. 



Sib : The character and value of property pertaining to the Astrophysical 

 Observatory are approximately as follows : 



Buildings $8, 900 



Apparatus 40, 300 



Library and records 7,500 



During the past year a small fireproof shelter has been erected in the north- 

 east corner of the Observatory inclosure to contain storage batteries and an 

 alternating-current generator, and to serve as a distributing center for all the 

 electrical currents used for the Observatory. An underground power line has 

 been laid by the electric lighting company to connect the Observatory and 

 the main Smithsonian building directly with the main on B street independently 

 of the National Museum. This fireproof building and power line cost $1,400. 



The two shelters occupied in 1905 by the expedition on Mount Wilson have 

 been improved in a manner adapting them to maintain a more uniform tem- 

 perature, and a tower and third small shelter for cloud reflection experiments 

 have been erected. The total cost for these improvements was $200. 



Apparatus for research has been procured at a cost of $1,000, of which $200 

 was chargeable to the appropriation of 1905-6. 



The usual scientific periodicals have been continued, a few books of reference 

 have been purchased, and some periodicals and books have been bound at a 

 total cost for the Observatory library of $60. 



No losses of property have occurred. 



Personnel. — The Observatory suffered the loss of its distinguished founder 

 and director in the death of Secretary S. P. Langley, on February 27, 1906. 



Mr. L. R. Ingersoll served as temporary bolometric assistant from July 1, 

 1905, to September 8, 1905, and again from June 16, 1906, to July 1, 1906. 



Miss F. A. Graves was appointed computer beginning January 10, 1906. 



Work of the Obsebvatoby. 



During the past year the work of the Observatory has been steadily directed 

 with the aim of securing proof of the suspected variability of the sun, but for 

 convenience the year's work will be described under the following classification : 



1. Miscellaneous work. 



2. Observations at Washington. 



3. Observations on Mount W^ilson. 



4. General statement of results. 



MISCELLANEOUS WOEK. 



Preparation for publication. — The research on a possible variability of the 

 solar radiation has been continued so long and has given promise of leading 

 to results of such definiteness and importance as to justify its publication as 



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