KEPORT OF THE SECRETARY. 35 



the sun of unequal brightness, which, rotating with the sun, strike 

 the various planets successively in the order of their longitudes, 

 and fall one after the other upon the earth as the sun by rotation 

 brings them into line with us. 



A new instrument for measuring nocturnal radiation, devised by 

 Messrs. Abbot and Aldrich and constructed at the observatory in- 

 strument shop, was successfully tried during the year. It is provi- 

 sionally called the "honeycomb pyranometer." The instrument is 

 almost as sensitive as a flat blackened strip and, moreover, has the 

 valuable property of being fully absorbing, which a strip has not. 

 It is an instrument of great promise for standard measurements of 

 various kinds of radiation. 



Through the generosity of Mr. John A. Roebling, of New Jersey, 

 it was made possible to move the Smithsonian observing station pre- 

 viously located on the plain near Calama, Chile, to a near-by moun- 

 tain above the interference of dust and smoke. With the remainder 

 of Mr. Roebling's grant it is proposed to establish a new observing 

 station on the Harqua Hala Mountain, in Arizona, one of the most 

 cloudless regions in the world. The establishment of these two sta- 

 tions so widely separated from one another will make it possible 

 to obtain nearly every day in the year check observ ations of the solar 

 constant of radiation, laying a firm foundation of solar observa- 

 tions from which meteorologists will be able to determine whether 

 the variations in the sun are of value, as present results indicate, in 

 forecasting weather conditions. However, with the limited funds at 

 his disposal, Doctor Abbot found it necessary to transfer apparatus 

 from the Mount Wilson station to the new Harqua Hala station, and 

 he urges in his report that Congress appropriate sufficient money to 

 provide for independent observing equipment for both stations and 

 for needed improvements to the Arizona station. 



INTERNATIONAL CATALOGUE OF SCIENTIFIC 

 LITERATURE. 



The United States Regional Bureau of the International Catalogue 

 of Scientific Literature is intrusted with the duty of collecting, in- 

 dexing, and classifying titles of all scientific papers published in 

 the United States to form part of the International Catalogue issued 

 by a central bureau in London. 



The enterprise was begun in 1900, and published annually 17 vol- 

 umes up to 1913. Fifteen volumes for the year 1914 have been 

 printed, and much of the material for the fifteenth issue is now in 

 the hands of the central bureau, its publication being delayed by 

 financial difficulties brought about by the war. A conference has 

 been called by the Royal Society in London, September 28 next, to 



