Smithsonian Report. 1931. — Dunham 



PLATE 1 



A.aAquilae. Rapid rotation. All lines widened; B.aCtjgni. No noticeable rotation. Lines 

 not widened; C, Sirius. Moderate pressure in the atmosphere. Hydrogen lines widened by 

 electric fields. Metallic lines relatively narrow; D,aCygni. Very "low jiressure in the atmos- 

 phere. Hydrogen lines relatively narrow; E, F, G, Flash spectrum of the solar atmosphere 

 photographed at Honey Lake, Calif., April 28, 1<J30. 75, a region in the violet. The left mem- 

 ber of theclo.se pair of crescents is due to ionized calcium (H), while the right member is due to 

 hydrogen (He) . The two strong crescents at the left of F are due to ionized strontium (X4077) 

 and hydrogen (US). G shows the strong H7 crescent of hydrogen in the blue with many 

 weaker crescents caused by atoms of iron, titanium, and other metals 



