24 ANNUAL. REPORT SMITHSONIAN INSTITUTION, 1923 



(4) The search for systematic errors and the application of carefully de- 

 termined corrections to Montezuma results on the new basis. 



(5) The reductions of observations made at Mount Wilson in 1922 on the 

 form of the solar spectrum energy curve and on the spectrum energy curves 

 of 10 of the brighter stars. 



This large computing program has resulted in putting the two 

 stations on an equal footing in every possible way. 



At Mount Wilson the director and Mr. Aldrich redetermined the 

 form of the solar spectrum energy curve, varying the procedure as 

 far as possible so as to get several independent checks on the results. 

 They also accomplished the difficult task of the observation of the 

 prismatic energy spectrum of 10 of the brighter stars in the focus 

 of the 100-inch reflector on Mount Wilson. The results of both 

 of these researches were published in the Smithsonian Miscellaneous 

 Collections, volume 74, No. 7, 1923. 



The two observing stations at Mount Harqua Hala, Ariz., and 

 Mount Montezuma, Chile, have continued in operation throughout 

 the year, and the results have been very numerous. They had not 

 been critically compared at the close of the year. 



The work on solar radiation, begun in 1903, has been steadily im- 

 proved, until with the continuous year-round occupation for two 

 years of two first-rate observing stations the decisive test has been 

 made, proving the substantial character of solar variation. In short, 

 the director believes that there is no longer a reasonable doubt that 

 the sun varies or that the observations can reveal these variations 

 satisfactorily. It is now a question for meteorologists whether these 

 variations are of importance in weather forecasting. 



Just after the close of the fiscal year some preliminary observa- 

 tions were made on changes in the appearance of the sun accom- 

 panying changes in the output of radiation. Two years of record 

 prints from direct photographs and spectroheliograms of the sun 

 made at the Mount Wilson Solar Observatory were compared with 

 the corresponding two-year records of solar radiation, and there 

 were established four general rules or principles connecting the 

 solar radiation with the sun's visible appearance. 



INTEENATIONAL CATALOGUE OF SCIENTIFIC LIT- 



EKATUKE 



In the report of the Regional Bureau of the International Cata- 

 logue of Scientific Literature for 1922 attention was called to an 

 international convention to be held at Brussels during July, 1922, 

 to consider the affairs of the catalogue and to the proposals to be 

 submitted by the Smithsonian Institution. It is satisfactory to be 

 able to report that at this convention these proposals formed the 

 basis of the resolution whereby all the countries represented agreed 



