356 



On Spectroscopic Observations of the Sun. [Mar. 18, 



The D line of hydrogen (?) also once bore a similar appearance. 



Secondly, as to the other phenomena which accompanied this strange 

 behaviour of the F line, and were apparently the cause of it. 



In the same field of view with F, I recognized the barium-line at 

 1989-5 of KirchhofFs scale. 



Passing on, the magnesium -lines and the enclosed nickel-iron-line were 

 visible in the chromosphere. The magnesium was projected higher into the 

 chromosphere than the barium, and the nickel or iron was projected higher 

 than the magnesium. I carefully examined whether the other iron-lines 

 were visible in the spectrum of the chromosphere ; they were not. 



I also searched for the stronger barium -lines in the brighter portion of 

 the spectrum ; but I did not find them, probably owing to the feeble 

 elevation of the barium-vapour above the general level of the photo- 

 sphere, which made the observation in this region a very delicate one. 



I detected another chromosphere-line very near the iron-line at 1569'5 

 (on the east side of it) . 



The sodium-lines were also visible. 



Unfortunately clouds prevented my continuing these interesting observa- 

 tions ; but the action was evidently toning down. 

 "Here, then, we have an uprush of 

 Barium, 

 Magnesium, 

 ? Nickel, 

 and an unknown substance 

 from the photosphere into the chromosphere, and with the uprush a dense 

 prominence ; accompanying the uprush we have changes of an enormous 

 magnitude in the prominence ; and as the uprush ceases the prominence 

 melts away. 



As stated in the former part of this paper, the barium- and magnesium- 

 lines were thinner than the corresponding Fraunhofer lines. In con- 

 nexion with this subject, I beg to be allowed to state that I have com- 

 menced a careful comparison of KirchhofFs map with the recently pub- 

 lished one of Angstrom. From what I have already seen, I believe other 

 important conclusions, in addition to that before alluded to, may be derived 

 from this comparison ; but I hesitate to say more at present, as I have not 

 yet been able to compare Angstrom's maps with the sun itself, or to examine 

 the angular diameters of the sun registered at Greenwich during the pre- 

 sent century. 



On the 14th inst. I also succeeded in detecting the hydrogen -line in the 

 extreme violet in the spectrum of the chromosphere. 



The Society then adjourned over the Easter Recess to Thursday, April 8. 



