Smithsonian Report, 1910. — Deslandres. 



— 



Plate 1, 



A ig.e.o* 



if 

 . S 



•>fc '*..': 



Upper K3 layer of calcium. 



Mean K 2 layer of calcium. 

 Spectroheliograms of September 18, 1908. 



(Negatives.) 



