REPORT OP THE SECRETARY. 37 



permitted. This plan will be continued- It has not been carried for- 

 ward as rapidly as the necessities demand, owing to the fact that 

 the appropriation granted, for a number of years, has been but Little 

 more than sufficient for the maintenance of the park. 



Attention has before been called to the desirability of securing for 

 the park the narrow tracts of land lying between its boundaries and 

 the recently established highways on the southeast and west. The 

 highways Avere located b}^ the Engineer Commissioner of the District 

 as close to the park as the topography would permit, in order to 

 reduce these tracts to a minimum. It is estimated that the land in 

 question can be acquired by condemnation for $40,000. and an item 

 for this purpose is submitted in the estimates. 



The collection of animals at the close of the fiscal year numbered 

 1,193. The small mammal house, which has been under construction 

 for several years, was opened to the public on November 15. To it 

 were transferred the collection of monkeys, as there had always been 

 a difficulty in keeping these animals in the proper condition of health 

 in their previous quarters. Work upon two additional bear yards 

 has been contracted for and considerable repairs made to some of 

 the older cages. The Adams Mill road was overhauled and resur- 

 faced during the autumn of 1906, and the planting of trees was car- 

 ried on at suitable times as far as the available fund permitted. 

 Five of the more important buildings were heated from the central 

 heating plant, installed during the previous year. The specialists 

 of the Department of Agriculture were offered opportunities for 

 pathological studies when animals died, and such dead animals as 

 might be useful to the national collections were sent to the National 

 Museum. 



ASTROPHYSICAL OBSP^RVATORY. 



The work of the Astrophysical Observatory, carried on under the 

 supervision of Mr. C. G. Abbot, who was appointed director March 

 1, 1907, has consisted of observations at the Mount Wilson Observa- 

 tory and at Washington, and the preparing of Volume II of the 

 Annals of the Observatory. About seventy days on Mount Wilson 

 were devoted to observations of the " solar constant " of radiation, 

 on which the staff of the observatory had been at work for some 

 years. The results were generally excellent. A new continuous 

 recording pyrheliometer is in course of construction for this work, 

 of different dimensions and construction from the one at present in 

 use. Much attention was paid to the observation of the intensity 

 of light reflected from clouds, with a view to the determination of the 

 albedo or total reflection of the earth. The quality and amount of 

 the light of the skv was also measured on several davs. 



