REPORT OF THE SECRETARY. 23 



The study and analysis of Indian music is a subject to which the 

 bureau has devoted considerable attention during the last few years, 

 and there have already been published two bulletins on Chippewa 

 music, which have attracted much attention in the musical world. 

 There is now in press an extended account of " Teton Sioux Music " 

 wdth transcriptions of 240 songs and about 100 illustrations; and a 

 paper on the music of the Ute Indians is in preparation. 



The collection of manuscripts pertaining to American Indians which 

 has been accumulated by the bureau during the last 30 years now 

 numbers about 1,700 items. Many of these manuscripts have come to 

 be of priceless value, comprising as they do records which it would 

 be impossible now to duplicate. There was added to this collection 

 during the last year a number of interesting records, including a 

 Laguna Indian dictionary, 49 Arapaho and Gros Ventre notebooks, 

 the war record of " Sitting Bull " depicted in 55 pictographs, and a 

 photostat copy of "A Grammar of the Pottewatomy Language." 



The bureau issued two bulletins, and there was in press at the Gov- 

 ernment Printing Office at the close of the year the twenty-ninth, 

 thirtieth, thirty-first, and thirty-second annual reports, and four 

 bulletins. The completion of several of these works is delayed by 

 the European war, the authors in some cases residing in belligerent 

 countries. The distribution of publications aggregated 10,185 vol- 

 umes and pamphlets. There were about 500 books added to the 

 library, which now numbers 20,237 volumes, 13,188 pamphlets, and 

 several thousand unbound periodicals. 



ASTROPHYSICAL OBSERVATORY. 



One of the principal researches by the Astrophysical Observatory 

 during the past year was the continuation of observations as to the 

 intensity of solar radiation at various altitudes, wnth a view to defi- 

 nitely determine the value of the solar constant of radiation. By 

 means of sounding balloons, to which were attached automatic record- 

 ing pyrheliometers, successful records were secured up to a height of 

 25,000 meters or about 15 miles, where the barometric pressure is only 

 one twenty-fifth that at sea level. Director Abbot, in his report 

 and in a special publication (Smithsonian Miscellaneous Collections, 

 Vol. 65, No. 4, June 19, 1915), reviews the observations in solar radia- 

 tion made at various altitudes from sea level up to the highest prac- 

 ticable mountain peak (Mount Wliitney) , thence in a balloon as high 

 as man could live, thence to a height of 15 miles, and concludes that 

 the solar constant of radiation is 1.93 calories per square centimeter 

 per minute. Dr. iVbbot discusses also the interesting fact that con- 

 siderable fluctuations of the " solar-constant " values occur from day 

 to day ranging over nearly 10 per cent between the extreme limits, 



