LIST OF PLATES. 



Skc^rktary's Report : Page. 

 Platu I. Location of aiiinial (ii;;irters in the National /oolo,u;ical Park.. 70 

 II. Plan of main floor of new house for animals. National Zoo- 

 logical Park 70 



III. Bird cage at Louisiana Purchase Exposition 72 



IV. (rreat brown hear from Alaska. Leopard in National Zoo 



logical Park 73 



V. Ground jilan of the observatory inclosure 78 



VI. New form of bolometric apparatus 78 



VII. Terrestrial temperature and solar radiation, 1903 . S2 



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



nm 82 



IX. Smithsonian and National Museum St. Louis exhibit .... 100 



X. St. Louis exhiltit of National Museum 100 



XI. Central court, Smithsonian pavilion at St. Louis 104 



XII. Entrance to St. Louis exhibitoftheAstrophysical 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, lOO.'J _ _, 113 

 The Rumford Spectroheliooraph (Hale and Ellerman): 



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



Yerkes refractor _ . _ . 146 



II. The curvature of lines in the spectroheliograph, fig. 2, H and 



K lines on the disk, etc ' 146 



III. Fig. 1, K line on the disk and at the limb : fig. 2, H and K lines 



in electric arc ; fig. 3, minute calcium flocculi (Hj) - - - _ 148 



IV. The sun, showing calcium flocculi 148 



V. Fig. 1, low level (Hj) section of calcium flocculi; fig. 2. high 



level (H2) section of same flocculi l.")0 



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



VII. Fig. 1 , Facula? ; fig. 2, calcium flocculi, low K, level ir)3 



VIII. Calcium flocculi, higher Kj level ; fig. 2, calcium flocculi, K.^ 



level 152 



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 Hi level 156 



XIII. Calcium flocculi, H. level. 158 



XIV. Hydrogen flocculi 158 



XV. Calcium flocculi, low H, level... 160 



XVI. Calcium flocculi, middle Hi level 160 



XVII. Calcium flocculi, high H, level. 162 



XVIII. Calcium flocculi, H2 level 162 



