274 H. Draper— Oxygen in the Sun. 
that oxygen gives brighter lines than wee other element in the 
un. But I would ask what reason we 
ground of brightness in the solar spectrum, it should be remem- 
-bered that there are theoretical considerations which Satie 
probable that there is always such a continuous backgroun 
during which the jar of the collision lasts. In the free path 
between the impacts they give out the characteristic wave 
gen lines above the photosphere, it will not, I think, follow ar 
there is no oxygen there, for there seems to be evidence tha 
. 
level of the reversing layer, and D, is a very bright line in the 
lower hror spl re Sethe de Ds 2. 4° ry a ding to it. 
VY 
