C. A. Young—Spectrum of the Corona. 53 
nickel is 58-01. The following table gives all the determina- 
tions made : 
Rothhoff, 59°20 Dumas, 59-028 
Hrdmann and { 58°20 to Russell, 58°74 
Marchand, | 58°60 Sommaruga, 58°026 
Schneider, 58°04 Winkler, 9-054 
Marignae, 58°40 to 59 Lee, 58°01 
In conclusion, my thanks are due to Dr. Gibbs for the selec- 
tion of the subject of my work, and for his advice during the 
course of my investigation. 
Cambridge, May, 1871. 
Art. X.—WNote on the Spectrum of the Corona; by Prof. C. A. 
Youne. 
Ty an article upon the Solar Corona, which appeared in the 
May number of this Journal, I wrote, “very perplexing also 
1s the fact that the faint continuous spectrum, which must be in 
part produced by this polarized component of the corona’s light, 
shows no discoverable traces of the dark lines of the ordinary 
sunlight-spectrum. Probably they exist, but are in some way 
masked so that they are not easily detected.” : : 
On further reflection, however, I believe the matter is readily 
explained, and that on the other hand it would have been re- 
markable if we had been able to bring out the Fraunhofer lines. 
The truth is that the reflected photospheric sunlight forms 
only one small fraction of the total coronal radiance, the other 
Constituents of which so far preponderate that it becomes very 
difficult to detect in the general spectrum the characteristics of 
this reflected light. ; 
The spectrum of the corona is, in all probability, composed of 
at least four superposed elements. : 
Ist. A continuous spectrum, without lines either bright or 
dark, due to ineandescent dust—that is, to particles of solid or 
liquid meteoric matter near the sun. For although I am not 
able to admit with Mr. Proctor that the whole explanation of 
the corona is involved in the presence of such meteoric particles, 
must: become incandescent and give such a spectrum as de- 
scribed. 
2nd. A true gaseous spectrum of the second order, consisting, 
like all such spectra, of a more or less bright continuous back- 
gro ith well marked maxima or bright lines. In this 
one bright line (1474) certainly exists, and perhaps several. So 
