THE ECLIPSE OF 1871. 129 



the corona, and the existence of substances beyond the 

 chromatosphere. I think the question whether the 

 corona is due to the terrestrial atmosphere is disposed 

 of (trancMe), and we now have before us the prospect 

 of the study of the extra-solar regions, which will be 

 *mbst interesting and fruitful.' 



In the spectroscopic study of the corona Janssen 

 achieved a noteworthy success. Hitherto astronomers 

 had failed in recognising on the faint rainbow-tinted 

 spectrum, forming a background, as it were, to the 

 distinctive bright-line spectrum of the corona, those 

 dark lines which are seen in the spectrum of solar 

 light. The inference was that very little or none of 

 the coronal light is reflected sunlight. Janssen, how- 

 ever, besides detecting several bright lines which had 

 not hitherto been recognised, saw also the chief solar 

 dark lines. Strangely enough, he appears to infer 

 from their presence that the corona exercises an 

 absorptive effect on light which would otherwise 

 produce a rainbow-tinted spectrum unstreaked by dark 

 lines. To me, the more natural explanation appears to 

 be that a portion of the coronal light is due simply to 

 the reflection of sunlight from the cosmical matter 

 undoubtedly surrounding the sun. Janssen himself 

 recognises the existence of such matter, since in his 

 remarks on his observations he says, 'Besides the 

 cosmical matter independent of the sun, which must 

 exist in his neighbourhood, the observations demon- 

 strate the existence of an excessively rare atmosphere, 

 mainly of hydrogen, extending far beyond the 



III. K 



