REPORT OF THE SECRETARY. it 
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 were located by 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 OBSERVATORY. 
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 sky was also measured on several days. 
