LIST OF PLATES. 



Becretary's Report : P.iko. 

 Plate I. Location of animal (piai'ters in the National Zoolo,ii:ical Park. _ 70 

 II. Plan of main tioor of new honse for animals. National Zoo- 

 logical Park 70 



III. Bird cage at Louisiana Piirchase Exposition 73 



IV. (Ireat brown bear from Alaska. Leopard in National Zoo- 



logical Park 72 



V. Ground plan of the observatory inclosure 78 



VI. New form of bolometric apparatus 78 



VII. Terrestrial temperature and solar radiation, 1903 83 



VIII. Intensity of radiation along diameter of solar disk. September, 



1903 S3 



IX. Smithsonian and National Museum St. Louis exhilut 100 



X. St. Loiiis exhibit of National Museum 100 



XL Central court, Smithsonian pavilion at St. Louis 104 



XII. Entrance to St. Louis exhibit of the Astrophysical Observatory. 104 



XIII. St. Louis exhibit of the National Zoological Park . . . 106 



XIV. St. Louis exhibit of the Bureau of Exchanges '. 106 



Experiments with the Aerodrome (Langley): 



Plate I. Instantaneous photograph of the launch of October 7, 1903 _ _ _ 113 

 The Rumfori) SPECTROHELKXiRAPH (Hale and Ellerman): 



Plate I. The Rumford spectroheliograph attached to the 40-inch 



Yerkes refractor - ^ - . 146 



II. Tlie curvature of lines in the spectroheliograph. fig. 3, H and 



K lines on the disk, etc 146 



III. Fig. 1, K line on the di.sk and at the limb ; fig. 3, H and K lines 



in electric arc ; fig. 3, minute calcium flocculi (H^) 1 48 



IV. The sun, showing calcivim flocculi 148 



V. Fig. 1, low level (Hj) section of calciunl flocculi; fig. 3. high 



level (Hj) section of same flocculi 150 



VI. General appearance of sun's disk at H^, level 150 



VII. Fig. 1 , Faculae : fig. 3, calcium flocculi, low K, level 153 



VIII. Calcium flocculi, higher Kj level ; fig. 3, calcium flocculi, K^ 



level 153 



IX. Hydrogen flocculi _ 154 



X. Fig. 1 , hydrogen flocculi ; fig. 2, calcium flocculi. .-. 154 



XI. Calcium flocculi, low H, level. 156 



XII. Calcium flocculi, middle H, level 156 



XIII. Calcium flocculi, H. level. 1,58 



XIV. Hydrogen flocculi 1.58 



XV. Calcium flocculi, low H, level 160 



XVI. Calcium flocculi, middle Hi level 160 



XVII. Calcium flocculi, high H, level 163 



XVIII. Calcium flocculi, H2 level 162 



IX 



