EEPORT OF THE SECRETARY. 25 



On Mount Wilson Mr. Aldrich continued the observations of the 

 solar constant of radiation, and in September, 1918, made an inter- 

 esting observation in cooperation with the Army Balloon School at 

 Arcadia, Calif., on the measurement of the reflection of sun and 

 sky radiation from layers of fog, which led him to conclude that 

 a great horizontal fog bank reflects to space 78 per cent of the radia- 

 tion of the sun falling upon it. 



The preparation of Volume IV of the Annals of the Astrophysical 

 Observatory has been in the hands of Dr. Abbot since February; it 

 includes the results of measurements from the year 1913. Mr. Fowle 

 has continued the work of revising the Smithsonian Physical 

 Tables, in which he has received valuable aid from the various 

 scientific departments of the Government and from individuals in 

 colleges and industrial corporations. 



INTERNATIONAL CATALOGUE OF SCIENTIFIC 

 LITERATURE. 



Tlie United States Regional Bureau of the Catalogue, supported 

 by congressional appropriation under the direction of the Smith- 

 sonian Institution, undertakes to list and index all scientific articles 

 appearing in the United States each year. These titles are for- 

 warded to the Central Bureau in London, where they are incorpor- 

 ated with the lists from al] other countries in a comprehensive cata- 

 logue of the 3^ear's scientific work of the world. Tlie war and the 

 chaotic conditions in Europe since the war, have greatly- liampered 

 the work of the catalogue and it has been recognized for several years 

 that a general reorganization will be necessary when conditions be- 

 come more settled. 



The Central Bureau has published during the year 8 volumes of 

 the Thirteenth Annual Issue, completing that issue, and 12 of the 

 IT volumes of the Fourteenth Issue have appeared. The United 

 States Bureau lias continued to gather and index the scientific titles 

 in this country, and in some of the sciences, notably zoology, the titles 

 have been classified far in advance of the published volumes. 



It has been recently announced by the Royal Society of London, 

 the principal sponsor of the catalogue since its inception, that after 

 the completion of the Fourteenth Annual Issue a new financial ar- 

 rangement will be necessary in order to continue the work, and scien- 

 tific establishments and academies throughout the world have been 

 asked to offer suggestions as to the best method of accomplishing this 

 end. 



