40 KEPORT OF THE ACTING SECRETAKY. 



while on the other the back yards of houses would extend to the 

 park fence. The streets in question would form more appropriate 

 boundaries than now exist in those directions, and the acquirement 

 of the land would help to preserve the natural beauties of the park. 



The number of animals in the park at the close of the year was 

 1,272, of which 509 were mammals, 643 birds, and 130 reptiles. 



It is gratifying to record the continued cooperation of the Depart- 

 ment of State, through its representatives abroad, in the acquisi- 

 tion by gift or exchange of a number of rare animals from various 

 parts of the world. 



ASTROPHYSICAL OBSERVATORY. 



This Observatory was established at the instance of the late Sec- 

 retary Langle}^, who acted as its Director, and was intended to 

 render possible the continuation of the epoch-making researches 

 which he initiated at Allegheny while in charge of the observatory 

 there. Mr. C. G. Abbot, his principal assistant for a number of 

 years, has been designated temporarily as acting director. 



The buildings of the Observatory, though of a temporary char- 

 acter, have been kept in good repair, and the inclosure surrounding 

 them has been enlarged to meet additional requirements of space. 

 As a measure of protection, a small fireproof shelter has been 

 erected in the northeast corner of the inclosure to contain the storage 

 batteries and an alternating current generator and to serve as a 

 distributing center for the electrical currents used in the Observatory. 

 Continued attention has been given to the improvement of the ap- 

 paratus, with the object of adapting it more effectually to the 

 researches which are prosecuted and of increasing its delicacy and 

 precision. 



The investigations of the Observatory have been conducted along 

 lines of definite research, and much important information relating 

 to solar radiation and to the transparency of the earth's atmosphere 

 and the sun's envelope has been collected. During the past year, as 

 for some time previously, the work has been steadily directed with 

 the aim of securing data in regard to the suspected variability of 

 the sun. As explained in the last report, arrangements were made 

 in the spring of 1905 to secure series of observations at a high alti- 

 tude under superior atmospheric conditions, the work being also 

 continued at Washington during the same period. This was rendered 

 possible through the courtesy of the Carnegie Institution and the 

 invitation of Prof. George E. Hale, director of its newly established 

 observatory for solar research on Mount Wilson, in southern Cali- 

 fornia. 



