58 THE BORDERLAND OF SCIENCE. 



mitted at once that nothing in their aspect, on a nearer 

 view, encourages such a conception of their nature. 



We visited both spot zones, and examined many spot 

 depressions in several stages of development. From 

 what we saw, we were led to the conclusion that spots 

 are caused, in the first instance, by the arrival of matter 

 from without, under such circumstances as to cause a 

 large portion of the solar atmosphere to be cooled. It 

 was clear, indeed, that much of the matter which con- 

 tinued to arrive from without caused a local increase 

 of the sun's heat. This was especially the case with 

 matter which arrived nearly on a vertical course. But 

 other matter, which descended less rapidly to the 

 surface, produced a precisely contrary effect, and as it 

 settled down in the solar atmosphere, displacing and 

 driving outwards the intensely bright solar clouds, it 

 appeared to cool the underlying matter in such sort as 

 to cause it to shine less resplendently then elsewhere. 

 But all round a region thus cooled, intense eruptive 

 action was invariably excited, every spot we visited 

 being literally circled about by prominences of greater 

 or less size. Some of these eruptions were so amazingly 

 active that the ejected matter (which seemed to come 

 from an immeasurable depth) was propelled with a 

 velocity even exceeding that of any of the matter which 

 arrived from without ; so that we could not but con- 

 clude that the matter thus disgorged was driven wholly 

 and for ever away from the sun. There were signs 

 which led us to believe that intense electrical action 

 was excited during these eruptions, and it does not 



