38 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1910. 



their interest to astronomers. While confident of the existence of 

 variations of this value extending over somewhat long periods and of 

 the probability of short-period variations as shown by the observa- 

 tions obtained on Mount Wilson, yet, in order to establish full confi- 

 dence in the minds of others of this variability of the sun's heat, there 

 is a very pressing need of observations made simultaneously at some 

 other place where they could be made over a longer period than is 

 possible at Mount Whitney. This new station should be so situated 

 that observations could be continued there while the winter rainy 

 season prevents them at Mount Wilson. A station in Mexico would 

 best fulfill such conditions. 



INTERNATIONAL CATALOGUE OF SCIENTIFIC 

 LITERATURE. 



The purpose of the International Catalogue of Scientific Literature 

 is to collect and publish in 17 annual volumes a classified index of the 

 current scientific publications of the world. This is accomplished 

 through the cooperation of 32 of the principal countries of the world, 

 which by means of regional bureaus, one in each country, prepare the 

 data necessary to index all scientific publications issued within their 

 domains. The material thus prepared is forwarded to a central 

 bureau in London for publication in the annual volumes. 



The various subscribers throughout the world bear the entire cost 

 of the actual printing and publication by the central bureau, but each 

 country taking part in the enterprise bears the expense of indexing 

 and classifying its own publications. 



The 17 annual volumes combined contain from 10,000 to 12,000 

 printed pages. The regional bureau for the United States furnishes 

 yearly about 30,000 citations to American scientific literature, which 

 is between 11 and 12 per cent of the total for the world. The bureau 

 for this country was for several years maintained from the funds of 

 the Smithsonian Institution, but is now supported through annual 

 congressional appropriations. 



Millions of dollars are being spent each year in scientific investiga- 

 tions, and many of the foremost men of the day are devoting their 

 entire time to such work. The results of their labors find publicity 

 through some scientific journal, of which there are over 5,000 that 

 are regularly indexed by the various regional bureaus, over 500 of 

 these journals being published in the United States. The titles of 

 hundreds of books and pamphlets are likewise cited in this Inter- 

 national Catalogue. There is thus furnished in condensed, accurate, 

 and permanent form a minutely classified index to practically all the 

 scientific literature of the world, for the method of classification 

 actually furnishes a digest of the contents, as well as the usual bibli- 

 ographical data, for each publication. 



