YET A YEAR LATER. 97 



regarded as demonstrated. It is at least unfortunate 

 that in thus summing up the results of the costly 

 eclipse expedition of December 1870, Sir W. Thomson 

 did not mention what particular discovery then made 

 seemed to his judgment to demonstrate the terrestrial 

 origin (in the main) of the coronal phenomena. One 

 can understand why Professor Tait, after hearing a 

 lecture on the general subject of solar eclipses, should 

 have remarked that what he had just heard convinced 

 him ,that the corona was of terrestrial origin ; for a 

 variety of eclipse phenomena seem at a first view to 

 suggest the atmospheric theory as the only available 

 explanation. Moreover, there can be no question that 

 some of the most striking phenomena presented at the 

 beginning and towards the close of totality are actually 

 due to the illumination of our atmosphere at those epochs 

 by departing rays or returning rays of direct sunlight. 

 After a lecture chiefly devoted to the consideration of 

 precisely such phenomena as these, and illustrated by 

 striking pictures of such phenomena, the opinion might 

 well be formed that the chief part of the coronal radiance 

 is simply atmospheric. It is only on a complete survey 

 of the subject, and especially of the evidence relating 

 to the corona as seen in the heart of the totality, that 

 the immense weight of evidence in favour of the real 

 existence of the corona as a solar appendage of amazing 

 extent is clearly recognised. But so far as could be 

 judged by the report, Sir W. Thomson's expression of 

 opinion related solely to the new results the dis- 

 coveries, in fact---effected last December; and it is 

 HI. H 



