REPORT OF THE SECRETARY. 93 
and renewed again on June 11, 1911, which tend to confirm the con- 
clusion that the sun’s output of radiation varies from day to day in 
a manner irregular in period and quantity. Assurance seems now 
complete that this latter result will be tested during the next fiscal 
year by long-continued daily observations taken simultaneously at 
two widely separated stations, where the atmosphere is believed to be 
specially favorable for such research. The definite determination of 
the laws governing the apparent variability of the “solar constant ” 
it is expected will be of much value in the probable forecast of 
climatic conditions from year to year. ; 
Measurements have also been made of the transparency, for long 
wave radiation, of columns of air containing known quantities of 
watervapor. Thisline of research promises highly interesting results. 
As mentioned on another page, arrangements have been made with 
several observatories, widely separated through the world, for the 
use of the standard silver-disk secondary pyrheliometer designed by 
the director of the Smithsonian Astrophysical Observatory. It is 
hoped to thus secure not only uniformity of radiation measures, but 
also a more exact knowledge of solar radiation and the influence of 
the terrestrial atmosphere upon it. 
INTERNATIONAL CATALOGUE OF SCIENTIFIC 
LITERATURE. 
The International Catalogue of Scientific Literature publishes, 
through the cooperation of countries in all parts of the world, a 
current classified index tothe literature ofscience. Seventeen volumes 
have been published annually, beginning with the literature of 1901. 
The organization consists of a central bureau in London and regional 
bureaus established in and supported by the 32 countries taking part 
in the enterprise. Supreme control of the catalogue is vested in an 
international convention, which met in London July, 1905, and July, 
1910, and is to meet every tenth year hereafter. The second inter- 
national convention met in London at the rooms of the Royal Society 
on July 12 and 13, 1910, and Mr. Leonard C. Gunnell, assistant in 
charge of the United States regional bureau, was sent by the Insti- 
tution as the delegate from the United States. The convention de- 
cided that on account of the success already achieved by the Interna- 
tional Catalogue and the great importance of the objects promoted, 
the enterprise would be continued. Attention was called to the ur- 
gent need of a permanent fund to aid in carrying on and extending 
the work. It was pointed out that although various regional bureaus 
for the collection of material were supported by the countries in 
which they were located, the maintenance of the central bureau for 
general administration and actual publication of the 17 annua! vol- 
umes was dependent entirely on the funds derived from the sub- 
