BIOGRAPHICAL NOTICE OF PROF. C. A. YOUNG, 841 



one-hundred-days men, mostly composed of the students of the col- 

 lege, who had volunteered at the call of Governor Tod, of Ohio, in 

 1862. The company was ordered to Vicksburg as escorts to a cartel 

 of exchanged prisoners, and Professor Young's health received injuries 

 during the expedition from which he has never entirely recovered. 



He returned to his native town of Hanover in 1865, to take the 

 professorship of Natural Philosophy and Astronomy in Dartmouth Col- 

 lege, the same which had been held by his grandfather, and his father, 

 who died in 1858. He was connected with this institution until 18TT. 

 During this time he was actively engaged on several astronomical ex- 

 peditions. He was a member of the party which, under the charge of 

 Professor J. H. C. Coffin, observed the eclij)se of August 7, 1869, at 

 Burlington, Iowa. Professor Young had devoted himself with great 

 assiduity to spectroscopic investigations, and he had charge of the 

 spectroscopic observations of the party. It was there that he discov- 

 ered the green line of the corona spectrum, and identified it with the 

 *' 1,474" line of .the solar spectrum. It may be observed that Professor 

 Harkness also discovered the same line on the same occasion, at Des 

 Moines, though, on account of the inferior power of his instrument, he 

 did not identify it correctly. In the winter of 1870-'71 Professor 

 Young was a member of the Coast Survey party which, under the 

 charge of Professor Winlock, observed the eclipse of December 22d 

 at Jerez in Spain. It was on this occasion that Professor Young made 

 his interesting discovery of what is called the " reversing layer " of 

 the solar atmosphere, giving a bright-line spectrum correlative to that 

 of the ordinary dark-line spectrum of sunlight. This remarkable ef- 

 fect is thus described by Professor Young, in his new work on the 

 sun : "At a total eclipse of the sun, at the moment when the ad- 

 vancing moon has just covered the sun's disk, the solar atmosphere of 

 course projects somewhat at the point where the last ray of sunlight 

 has disappeared. If the spectroscope be then adjusted with its slit 

 tangent to the sun's image at the point of contact, a most beautiful 

 phenomenon is seen. As the moon advances, making narrower and 

 narrower the remaining sickle of the solar disk, the dark lines of the 

 spectrum for the most part remain sensibly unchanged, though becom- 

 ing somewhat more intense. A few, however, begin to fade out, and 

 some even turn palely bright a minute or two before the totality be- 

 gins. But the moment the sun is hidden, through the whole length 

 of the spectrum, in the red, the green, the violet, the bright lines flash 

 out by hundreds and thousands, almost startlingly ; as suddenly as 

 stars from a bursting rocket-head, and as evanescent, for the whole 

 thing is over within two or three seconds. The layer seems to be only 

 something under a thousand miles in thickness, and the moon's mo- 

 tion covers it very quickly." 



In August, 1872, Professor Young was stationed at Sherman, Wy- 

 oming Territory, the summit of the Pacific Railroad, to make solar 



