i8 ROUGH WAYS MADE SMOOTH. 



about 280,000 miles opposite the solar poles, but opposite the 

 polar equator to about 670,000 miles. Its light was white. 

 This white light was not in the least radiated itself, but it 

 had the appearance of rays penetrating through it ; or rather 

 as if rays ran over it, forming symmetrical pencils diverging 

 outwards, and passing far beyond the boundary of the 

 white light. These rays had a more bluish appearance, and 

 might best be compared to those produced by a great 

 electro- magnetic light. Their similarity to these, indeed, 

 was so striking, that under other circumstances I should 

 have taken them for such, shining at a great distance. The 

 view of the corona I have described is that seen with the 

 naked eye. ... In the white light of the corona, close 

 upon the moon's edge, there appeared several dark curves. 

 They were symmetrically arched towards the east and west, 

 sharply drawn, and resembling in tint lines drawn with a 

 lead pencil upon white paper. . . . Beginning at a distance 

 of one minute (about 26,000 miles), they could be traced up 

 to a distance of about nine minutes (some 236,000 miles 

 from the moon's edge.' 



Almost all the features observed in this case correspond 

 closely with those noted and photographed during the eclipse 

 cf December, 1871. In other words the corona seen in 

 1867, when the sun was passing through the period of least 

 solar disturbance, closely resembled the corona seen in 

 1871, when the sun was nearly in its stage of greatest 

 disturbance. Even the spectroscopic evidence obtained in 

 1871 and July, 1878, may be so extended as to show with 

 extreme probability what would have been seen in 1867 if 

 spectroscopic analysis had then been applied. We cannot 

 doubt that the reddish inner corona, extending to a height 

 of about 140,000 miles, would have been found under spec- 

 troscopic analysis to shine in part with the light of glowing 

 hydrogen, as the reddish corona of 1871 did. The white 

 corona of July, 1878, on the contrary, shone only with such 

 light as comes from glowing solid or liquid matter. Here 

 then, again, the evidence is unfavourable to our theory; 



