2 14 The Smithsonian Institution 



dollars. The utility of such service having been demon- 

 strated at the Allegheny Observatory, the example was 

 followed a year later at Harvard College Observatory, and 

 afterward "time services " were for some years an important 

 source of income for quite a number of the observatories of 

 the United States. 



In the course of two or three years the affairs of the obser- 

 vatory became somewhat stable, and there was time for orig- 

 inal work in astronomy. Mr. Langley now began a period 

 of laborious and minute study of the features of the disk of 

 the sun. Indeed this was the one of the heavenly bodies 

 which could be most advantageously studied in Pittsburg, 

 where the heavens are usually obscured by clouds of smoke 

 and dust. In 1869 he was chosen a member of the party 

 sent out by the United States Coast Survey to observe the 

 total eclipse of August 7, and was stationed at Oakland, Ken- 

 tucky. His report, at this time submitted to Professor Joseph 

 Winlock, was his first published contribution to science. In 

 the winter of 1870 he accompanied another eclipse expedi- 

 tion to Jerez de la Frontera, in Spain, where he made impor- 

 tant observations upon the coronal rays, and found that the 

 polarization of the corona is radial. 



From this period dates the beginning of that brilliant series 

 of researches upon the solar atmosphere to which he has 

 since devoted so much of his time, and which soon gave him 

 high reputation at home and abroad. 



His telescope study of the sun's face, completed in 1873, re- 

 vealed the true character of the "granules " upon its disk, from 

 which, according to his estimate, much over three-quarters 

 of its light are derived. It also resulted in a better under- 

 standing of the structure and appearance of the sun-spots. 

 His picture of "A Typical Sun-spot," first exhibited in 1873 

 at the Portland meeting of the American Association for the 



