16 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1915. 



printed under congressional appropriation, so that a larger edition 

 and more widespread distribution is possible. 



Under the direction of the Institution are issued the various pub- 

 lications of its branches, (a) the Annual Eeport, the Proceedings, and 

 the Bulletins of the National Museum, including the series of Con- 

 tributions from the National Herbarium; (&) the Annual Reports 

 and Bulletins of the Bureau of American Ethnology; and (c) the 

 Annals of the Astrophysical Observatory. These series are all public 

 documents and are printed by means of annual allotments by act of 

 Congress. 



Smithsonian Contributions to Knowledge. — The requirements for 

 memoirs in this series are that they be accounts of extended original 

 research constituting important additions to knowledge. Since the 

 first appearance of this series in 1848, 35 quarto volumes containing 

 150 memoirs have been issued, the most recent one being the " Lang- 

 ley Memoir on Mechanical Flight," in which are recorded the results 

 of the late Secretary Langley's experiments establishing the practica- 

 bility of heavier-than-air flying machines. 



Smithsonian Miscellaneous Collections. — Fourteen papers forming 

 parts of four volumes of this series were issued during the year, 

 among them one paper on Cambrian geology by your Secretary. 

 Another interesting paper was that by Messrs. Abbot, Fowle, and 

 Aldrich recording new solar radiation researches, in the course of 

 Vv'hich free balloons carrying recording apparatus, ascended to a 

 height of over 15 miles and were found on their descent with the 

 records in good condition. As a result of these and other experi- 

 ments, the authors abide by their former results, namely, that " the 

 mean value of the ' solar constant ' is 1.93 calories per square centi- 

 meter per minute." In this series, the sixth revised edition of the 

 Smithsonian Physical Tables was issued, and was practically ex- 

 hausted at the close of the year, showing the continued popularity 

 and usefulness of this work. The publication of a further edition 

 was being considered at the close of the year. The usual annual 

 account of the Institution's explorations and field Avork was issued, 

 and being profusely illustrated, was of considerable popular interest. 



Smithsonian reyort. — The report for 1913 was received from the 

 printer and distributed during the year. Separates of the articles 

 forming the general appendix of the 1914 report were issued, the 

 completed volume, however, not being received from the printer until 

 shortly after the close of the fiscal year. Incorporated in the con- 

 gressional act providing for printing for the Institution and its 

 branches was a clause increasing the edition of the Smithsonian 

 annual reports from 7,000 to 10,000, a very desirable change, as the 

 edition of this volume has heretofore been exhausted almost imme- 

 diately following its appearance. 



