120 



-w THE CHEMISTRY OF THE SUN. 



[CHAP. 



the slit is no longer shown us as a perfectly straight line, it is 

 in fact a very irregular one ; and further than this, it branches 

 at a certain distance from the sun and becomes double. 



FIG. 53. Contortions of F line in a prominence. 



The next series of figures (Fig. 55) represents another obser- 

 vation of this bright r line of hydrogen. These various effects 



(111 111! Ill 



FIG. 54. Contortions of the hydrogen lines. 



were produced by varying the position of the slit a very little 

 indeed over a small and very brilliant prominence. 



The left-hand figure shows the appearance of this line when 



