88 SCIENCE IX SHOUT CHAPTERS. 



not yet been invented, all the telescopic details of spot 

 phenomena might have been described a j.riwi as necessary 

 consequences of the constitution I have above ascribed to the 

 sun. 



Not merely the great spot phenomena, but all the minor 

 irregularities of the photosphere follow with similarly demon- 

 strable necessity. Thus the many interfering solar tides mus j 

 throw up great waves, literally mountainous in their magni- 

 tude, the summits and ridges of which, being raised into higher 

 regions of the absorbing vaporous atmosphere that envelops 

 the photosphere, will radiate more freely, its dissociated matter 

 will combine more abundantly, and will thicken the photo- 

 sphere immediately below ; this thicker flame will be more 

 luminous than the normal surface, and thus produce the 

 phenomena of i\ie faculce. 



Besides these great ground-swells of the flaming ocean of the 

 photosphere, there must be lesser billows, and ripples upon 

 these, and mountain tongues of flame all over the surface. 

 The crests of these waves, and the summits of these flame-alps, 

 presenting to the terrestrial observer a greater depth of flaming 

 matter, must be brighter than the hollows and valleys between ; 

 and their splendor must be further increased by the fact that 

 such upper ridges and summits are less deeply immersed in the 

 outer ocean of absorbing vapors, which limits the radiation of 

 the light as well as the heat of the photosphere. The effect of 

 looking upon the surface of such a wild fury of troubled flame, 

 with its confused intermingling of gradations of luminosity, 

 must be very puzzling and difficult to describe ; and hence the 

 "willow leaves," "rice grain>," "mottling," "granules/* 

 "things," "flocculi," "bits of white thread," " cumuli of 

 cotton wool," "excessively minute fragments of porcelain," 

 " untidy circular masses," " ridges," " waves," " hill knolls," 

 etc., etc., to which the luminous ii regularities have been 

 compared. 



At the time I wrote, the means of examination of the edge 

 of the sun by the spectroscope was but newly discovered, and 

 the results then published referred chiefly to the prominences 

 proper. Since that, a new term has been introduced to solar 

 technology, the " sierra," and the observations of the actual 

 appearances of this sierra precisely correspond to my theoretical 

 description of the limiting surface of the photosphere, which 

 was written before I was acquainted with these observed facts. 

 This will be seen by reference to Chapter 10, the subject of 



