NO. 8 SAMUEL PIERPONT LANGLEV — AHBOT 29 



latter values of the table which concludes " On Hitherto Unrecog- 

 nized Wave-Lengths " are considerably too great. 



ANNALS OF THE ASTROPHYSICAL OBSERVATORY OF THE 

 SMITHSONIAN INSTITUTION, VOLUME 1 



As indicated in the remarkable passage already quoted from the 

 Mount Whitney Report, Langley's prophetic instinct told him that 

 in the study of the sun's radiation rested the main hope of long-range 

 weather forecasting. He moved toward the establishment of solar 

 research at the Smithsonian Institution soon after becoming Secretary. 

 He writes : 



" This book is the result of a research originally due to a discovery, 

 made in the year 1881 with the then newly invented bolometer, in 

 the clear air of an altitude of over 12,000 feet, of solar heat in a 

 then unknown spectral region now called the ' lower infra-red spec- 

 trum.' The bolometer has since been used to explore and to map the 

 region in question, through the long succeeding intervals, in the latter 

 part of which it has reached an accuracy and a sensitiveness greater 

 than I could once have hoped for. 



" This map is now (June 18, 1900), after years of constant work, 

 finally published in the present form; not because this edition is 

 final, but because the long labor must come to some term, and because 

 I desire to see its results published while I may hope to see them made 

 useful. 



" While we are far from looking forward to foretelling by such 

 means the remoter changes of weather which affect the harvests, or 

 to results of such importance as the power of such a prevision would 

 indicate, still it is hardly too much to say that we appear to begin 

 to move in that direction, and it seems to me that my own early hopes 

 of making the study of the solar energy not simply an interesting 

 scientific pursuit, but one of material usefulness, may one day be 

 justified. 



" In the reports of the Secretary of the Smithsonian Institution 

 for the years ending June 30, 1888 and 1889, mention is made of the 

 hope then cherished of erecting and equipping an observatory for 

 astrophysical research; and in the year following, 1890, he is at last 

 ' able to say that this object has assumed definite shape in the con- 

 struction of a temporary shed, begun on November 20, 1889 and 

 .... completed about the ist of March, 1890. This building is of 

 the most inexpensive character, and is simply intended to protect the 



