1 8 THE POPULAR SCIENCE MONTHLY 



It was hoped and the hope would appear to have been justified that 

 during the late eclipse these doubts would be finally removed. A few 

 weeks must elapse even after the present paper appears, and five or 

 six from the present time of writing, before the sun-painted pictures, 

 which are to decide the question, can be in the hands of the judges. 

 But, from the description which has already reached us, we can 

 feel very little doubt as to the nature of the decision which will be 

 arrived at. 



A brief sketch of the progress of the inquiry into the subject 

 of the solar corona will serve to exhibit the nature of the doubts 

 which the recent expeditions to the Indian seas were intended to 

 remove. 



From very early ages it had been known that when the sun's disk 

 is wholly concealed by the moon, a glory of light starts into view, ren- 

 dering the scene less terrible, though scarcely less striking, than it 

 would be were total darkness to prevail. 



Now, gradually, it began to be recognized that this glory around 

 the sun consisted of several distinct portions. In the first place, quite 

 close to the moon's black body, a very narrow ring of light had been 

 observed, so bright that many astronomers were led to believe that 

 the sun was not in reality totally concealed, but that a ring of sunlight 

 remained even at the moment of central eclipse. This excessively 

 bright ring of light is not, however, always seen, if (as many accounts 

 suggest) it is to be distinguished from the bright inner corona of 

 which I shall presently have to speak. During the recent eclipses we 

 have had no clear evidence respecting this brilliant but very narrow 

 ring ; and it is just possible that the accounts derived from earlier 

 eclipses have been a little exaggerated. 



Then, secondly, a red border is seen around portions of the black 

 disk of the moon. This border has commonly a serrated edge, and has 

 been called the sierra, from a well-known Spanish name for a range of 

 hills. From what thus resembles a chain of rose-colored mountains, 

 appear to spring certain red projections which have been called the 

 solar prominences. Their general appearance during eclipse may be 

 inferred from the description given by those who first observed them, 

 in 1842, who compared the moon's disk surrounded by these glowing 

 objects to a black brooch set round with garnets. But it is now 

 known that such names as prominences and protuberances are not 

 properly applicable to these red objects, and that the word sierra is 

 equally inapplicable to the rim of colored light beneath the red projec- 

 tions. The prominences as well as the sierra (for, however unsuitable, 

 the names continue in use) are in reality formed of glowing gas, hy- 

 drogen being their chief constituent element, but other elements being 

 also present in a gaseous form. Only, the reader must not run away 

 with the notion that these great red masses, some of which are more 

 than a hundred thousand miles in height, are of the nature of our gas- 



