ii'lC UiUTUllES. 



FIG. 



If 



I 



Fig. 9 represents in A to E the different 

 aspects of such a spot as it cornea iiear the 

 odgc of the sun. 



Just on the edge of these spots there are 

 spectroscopic indications of the most violent 

 motion, and in their vicinity there are often 

 large protuberances ; they show compara- 

 tively often a rotatory motion. They may 

 bo considered to he places where the cooler 

 gases from the outer layers of the sun's at- 

 mosphere sink down, and perhaps produce 

 local superficial coolings of the sun's mass. 

 To understand the origin of these phenomena, 

 it must be remembered that the gases, as 

 they rise from the hot body of the sun, are 

 charged with vapors of difficultly volatile 



According to H. C. Vogel's observations In Both- 

 kamp, to a heizht of 70,000 miles. Tho spcctrocpic 

 displacement of the lines showed yeUvitiex of IB to 

 n mile* in a second ; and, according to Lockyer, of 

 even 87 to 48 miles. 



metals, whlcn expand as they ncencf, and 

 partly by their expansion, aud partly bv 

 radiation into space, must become cooled. 

 At the same time, they deposit their morn 

 difficultly volatile constituents as fog or 

 cloud. This cooling can only, of course, ba 

 regarded as comparative ; their temperature 

 is probably, even then, higher than any tem- 

 .pe.rature attainable on the earth. If now tho 

 tipper layers, freed trom the heavier vapors, 

 sink down, there will be a space over th 

 sun's body which is free from cloud. They 

 appear then as depressions, because about 

 them are layers of ignited vapors a ) much aa 

 500 miles in height. 



Violent storms cannot fail to occur in th 

 sun's atmosphere, because it is cooled on the 

 outside, and the coolest and comparatively 

 densest and heaviest parts come to lio over 

 (he hotter and lighter ones. This is the 

 reason w>>v we have frequent, and at timQ 



