38 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
Measurements for the determination of the “solar constant ” were 
also made at Washington whenever atmospheric conditions per- 
mitted. These are of great value as supplementary data to the Mount 
Wilson observations. 
Volume II of the Annals is in press, and includes an account of the 
work of the observatory from 1900 to 1907. Speaking broadly, the 
energy of the observatory has been devoted to an investigation of 
the intensity of the rays of the sun and the dependence of the earth’s 
temperature upon the radiation. 
The investigations have resulted in apparently definitely fixing the 
approximate average value of the “solar constant” at 2.1 calories 
per square centimeter per minute, and in showing decisively that 
there is a marked fluctuation about this mean value, sufficient in 
magnitude to influence very perceptibly the climate, at peat of in- 
land regions, upon the earth. 
The observatory buildings, although temporary, have been kept in 
good repair by a small expenditure. Plans have been made and 
contracts have been awarded for the installation of electrical light- 
ing and power to replace the present inadequate facilities, and some 
additions have been made to the research equipment and library. 
INTERNATIONAL CATALOGUE OF SCIENTIFIC 
LITERATURE. 
The International Catalogue of Scientfic Literature is a classified 
-author’s and subject catalogue of all original scientific papers pub- 
lished throughout the world. The organization consists of bureaus, 
established in each of the civilized countries, whose duty it is to 
furnish references to the scientific publications issued within their 
several regions, these references being assembled, edited, and pub- 
lished in seventeen annual volumes by a central bureau in London. 
The cost of printing and publishing is met by the subscribers to 
the Catalogue; and American universities, libraries, and scientific 
societies alone have shown their appreciation of the work by making 
advance subscriptions amounting to over $30,000. The cost of col- 
lecting and indexing the material for the Catalogue is in each case 
borne by the countries taking part in the work, and is for the most 
part derived from direct governmental grants. 
The Regional Bureau for the United States was organized in 1901 
by the Smithsonian Institution, and was maintained by funds of the 
Institution until it was placed on a firm footing by an appropriation 
made by Congress of $5,000, which became available for use July 1, 
1906. A further grant of $5,000 became available July 1, 1907. 
Each regional bureau collects, indexes, and classifies the current sci- 
entific literature published within the country it represents, and fur- 
nishes the material to the central bureau in London for publication. 
