KEPORT OF THE SECRETARY. 3S 



solar radiation, its variability from day to day, and the effect of the 

 atmospheric water vapor in absorbing the radiations of great wave 

 length such as are emitted toward space by the earth. Much atten- 

 tion has been given to the design, construction, and testing of new 

 apparatus for these researches, including apparatus for measuring 

 the sky radiation, special recording pyrheliometers to be attached 

 to free balloons for the purpose of measuring solar radiation at great 

 altitudes, and a tower telescope at the Mount Wilson Station. 



The principal results of the year include : A new determination of 

 the number of molecules per cubic centimeter of gas, depending on 

 measurements at Mount Wilson of the transparency of the atmos- 

 phere; successful measurements by balloon pyrheliometers of the 

 intensity of solar radiation up to nearly 45,000 feet elevation above 

 sea level. The results tend to confirm the adopted value of the solar 

 constant of radiation. Most important of all, the investigation by 

 the tower telescope at Mount Wilson shows that the distribution of 

 radiation along the diameter of the sun's disk varies from day to day 

 and from year to year. These variations are closely correlated with 

 the variations of the total amount of the sun's radiation. Thus the 

 work of the year yields an independent proof of the variability of 

 the sun and tends to elucidate its nature. 



INTERNATIONAL CATALOGUE OF SCIENTIFIC 

 LITERATURE. 



The United States Bureau of the International Catalogue is ad- 

 ministered by the Smithsonian Institution through 'a small annual 

 appropriation by Congress. It is one of 33 regional bureaus in 

 various countries engaged in the collecting, indexing, and classify- 

 ing of scientific publications of the year, and the classified references 

 are forwarded to the central bureau in London, where they are col- 

 lated and published in a series of 17 annual volumes covering each 

 branch of science and aggregating about 8,000 printed pages. These 

 volumes are sold at an annual subscription price of $85, chiefly to 

 large reference libraries and important scientific institutions, the 

 proceeds covering in part the cost of publication. During the past 

 year there was forwarded to London from the United States bureau 

 a total of 28,606 reference cards, making a total of 318,936 cards 

 prepared in the United States since the system was organized in 

 1901. 



NECROLOGY. 



Augustus Octavius Bacon was born in Bryan County, Ga., Oc- 

 tober 20, 1839, and died in Washington City February 14, 1914. 

 He became a member of the Board of Regents in 1905 and for three 



