Smithsonian Report. 1950. — Lindblad 



PLATE 3 



1. Prominence I)hutograplied on November 26, 1948, by Y. (jhinan, iStockl 



Observatory. 



2. iMilarged reproduction of the flash spectrum from one picture of the cinemato- 

 graphic film obtained on July 9, 1945, by the Stockholm Observatory expedi- 

 tion at Bratt&s, Sweden. The spectrum of the solar atmosphere appears as 

 a series of emi.ssion lines. The strongest lines are those of hydrogen, begin- 

 ning at the limit of the Bahner series in the ultraviolet (extreme left), to the 

 red Hoc line (right-hand limit), and the II and K lines of calcium, a conspic- 

 uous pair on the left-hand side, and the lines of luslium, of which the strongest 

 line is the D3 line to the left of H oc . The continuous spectrum in the middle 

 is a part of the extreme '"photospheric" layer shining through a valley on the 

 moon. 



