38 REPORT OF THE SECRETARY. 



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 least 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. 



