THE SMITHSONIAN INSTITUTION 585 



ards of the world. The ancients, the Babylonians, the Greeks, and 

 others made no measurements of the quantity of heat received from 

 the sun. We can not tell accurately from any recorded observa- 

 tions prior to the year 11)00 what was then the intensity of the sun's 

 heat output. Since 1902 the Astroph3'sical Observatory has made 

 every year many exact measurements, so that our successors will be 

 able to compare their observations, even centuries hence, with those 

 which we are now making. 



Early in this series of observations it appeared that the sun's heat 

 is not constant but variable. In other words, the sun is a variable 

 star. This discovery, which was made about the year 1903, has been 

 confirmed by expeditions to California, Africa, South America, and 

 elsewhere, including measurements made at the summit of Momit 

 Whitney, the highest mountain in the United States. Since 1918 

 the Institution has maintained two stations — one in the United 

 States, one in Chile — cooperating to observe the sun's variation. The 

 results are being used in several countries for weather forecasting. 



The original establishment of the Astrophysical Observatory was 

 made with funds from private sources. Small Government appro- 

 priations for it have been available since 1891. A part of the income 

 derived from funds given to the Smithsonian by the late Mr. Thomas 

 G. Hodgkins for atmospheric investigations has been devoted to its 

 work since 1917. Mr. John A. Roebling contributed largely to its 

 support from 1920. 



THE NATIONAL ZOOLOGICAL PARK 



Secretary Langley, though an astronomer and a i^hysicist, had 

 been very strongly impressed by the fact that all of our largest and 

 most interesting wild animals were rapidly approaching extinction. 

 He conceived the idea of securing a tract of country, as primitive as 

 possible, that might be made a lasting refuge for these vanishing 

 races. He urged this project upon the attention of Congress, and 

 after three years of effort, in which he was supported by men of 

 science and educators as well as by lovers of animals, an initial 

 appropriation of $200,000 was made for the purpose in the year 1890. 



This sum was expended for the purchase of 1G7 acres of land, 

 beautifully diversified with woods and streams, in the suburbs of 

 Washington. A collection of about 2,000 living animals is now 

 the feature of the Zoological Park. There are numerous paddocks 

 and ranges for buffalo, deer, and other large mammals; lakes and 

 pools for waterfowl, seals, beaver, and other aquatic species; out- 

 door cages, some of large size, for hardy birds and mammals; and 

 houses and shelters for species requiring special care or heated 

 quarters during the winter months. The yearljj^ public attendance 

 exceeds 2,000,000 persons. 



