REPORT OF THE SECRETARY. 31 



mal that seems most popular is a male chimpanzee, about 4^ years 

 old, from the forests of French Congo. 



The number of visitors during the past year was 1,157,110, as com- 

 pared with 794,530 in the year preceding. This included 161 schools, 

 classes, etc., numbering 8,679 individuals. 



Eecent improvements include the construction of a hospital and 

 laboratory building and the grading of some ridges and gullies to 

 secure additional building sites and paddocks for the deer and other 

 large animals. 



As mentioned in previous reports an appropriation was made in 

 1913 for the purchase of several acres as an extension to the western 

 boundary of the park, but legal proceedings and complications inci- 

 dent to adjustment of values and benefit assessments caused such 

 delay that the appropriation, not being a continuing one, lapsed on 

 June 30, 1915, and Congress has failed to renew the allotment for this 

 much desired improvement. 



Many important needs are urged by the superintendent, some of 

 which I have mentioned year after year. One of these is an aviary 

 building for the birds now being housed in temporary quarters 

 greatly deleterious to their health. Other needs are a building for the 

 elephants, hippopotami, and similar animals; an ape house; a reptile 

 house ; a pheasantry ; an ostrich house ; an aquarium ; and an insect- 

 ary ; also a gatehouse and a permanent boundary fence. 



THE ASTROPHYSICAL OBSERVATORY. 



Observations of the solar constant were continued at Mount Wil- 

 son, Cal., from July to October, 1915, and were begun again in 1916. 



During the year there was published the results of solar-constant 

 observations made under Prof. Pickering's direction at Arequipa, 

 Peru, since August, 1912, with a silver-disk pyrheliometer lent by 

 the Smithsonian Institution. These observations confirm the vari- 

 ations of the sun observed at Mount Wilson. An interesting feature 

 of the Arequipa observations was the fact that the volcanic eruption 

 of Mount Katmai in 1912, which produced a great deal of dust over 

 the northern hemisphere, apparently had no effect on the atmosphere 

 south of the equator. 



The results of observations at Mount Wilson in 1913 and 1914 on 

 the distribution of radiation along the diameter of the sun's disk 

 were published during the year. It is thus shown that the average 

 distribution over the disk varies from year to year as well as from 

 day to day. 



Observations have been continued on the transmission of rays of 

 great wave length through long columns of air, which it is expected 

 will be of much interest in studying the earth's temperature as 

 dependent on radiation toward space. 



