REPORT OF THE SECRETARY. 33 
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 
T901. 
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 
73176°—su 19143 
