68 



trum, and the spectra of the sun, chromosphere, solar 

 prominences and corona as seen in the eclipse of 1869.] 



The spectrum of the chromosphere, the gaseous hiyer 

 in which the solar prominences originate, contained the 

 four h} drogen lines with several others not determined. 

 In the spectrum of the prominences were found, besides 

 these, four others, three of which were also found in the 

 corona ; of these two were rather faint, and have not 

 generally been seen. The third, which is called the 

 "1474" line, from its position on the standard scale, is 

 considered the characteristic line of the coronal spectrum ; 

 it indicates the presence of an unknown gaseous substance 

 which is also found in the sun, and probably thrown up 

 from it into the corona. In the corona have also been 

 seen the continuous spectrum, which would indicate in- 

 candescent solid or liquid matter, and the spectrum of 

 sunlight with its dark lines, which w^ould agree with the 

 polariscope in indicating reflected sunlight. 



Upon the testimony of the spectroscope, then, the 

 corona is of a very complex nature, for it shines with its 

 own light, shines with reflected sunlight, and contains an 

 unknown gaseous substance found also in the sun. But 

 the corona does not exhibit the same spectra in different 

 eclipses. In the last eclipse the change was especially 

 marked. The 1474 line was very faint — some observers 

 failed entirely to see it — while the continuous spectrum 

 was the marked feature, the dark solar lines being also 

 seen. This noticeable change in the spectrum, particu- 

 larly the unusual faintness of the 1474 line, points to a 

 connection between the sun and the corona which is one 

 of the most important results of the recent observations. 

 The sun has been for some time past in a state of unusual 

 quiescence ; the spots and prominences are few, the chro- 

 mosphere low. That at this time the corona should show 



