( 202 ) 
the direct photospheric light it is weak enough for the dark lines 
to be visible. Thus, not considering the presence of clouds, the 
absorption lines must yet, during the transition from the flash spectrum 
to the Faunhofer spectrum, at first show very faint and with 
abnormal relative intensities, then grow stronger, intensities appearing 
normal. 
Because the double lines are not sharply defined objects, it is 
difficult to give the width of these systems. But we can make settings 
on the brightest parts of the components and measure their distance 
with a reading microscope. It differs for the different double lines, 
still it generally lies between 0.7 and 1.3 AnasTRém’s units. Wider 
and narrower systems follow each other in irregular succession, but 
on an average the distance of the components appears to decrease 
as we proceed from the green to the violet. Perhaps this fact may 
be important for dispersion theories. 
With some lines the stronger component is that which has the 
greater, in others that which has the smaller wave-length. It happens 
that even in the same line (e.g. in the arcs of 4, and Hs on our 
plate) the two cases occur close by one another, which means that 
in neighbouring places of the sun’s atmosphere the density distri- 
bution of the absorbing gas is different in this, that at one place 
the average density along the path of the ray increases, at another 
decreases towards the sun’s centre. 
CAMPBELL states!) that in some cases where dark and bright 
lines are to be found together, they are separated from one another 
by a distance of from 0.4 to 0.5 AnasrRém’s units. This is about 
the half of the distance between the components of our double lines. 
We may here reasonably suppose that CAMPBELL was concerned 
with cases, where one of the components was strongly marked. A 
similar case is found on our photograph in fg, where the component 
with the greater wave-length is stronger over nearly its whole length 
than that with the smaller wave-length, and such is the case not 
only at the third contact but also during the second and even on 
the four plates, prepared for the corona spectrum, which were exposed 
for 5, 20, 190 and 60 sec. respectively. 
I have not found until now in any chromosphere line a peculiarity 
in the distribution of the light, which would make it necessary to 
ascribe even a part of this light to radiations, emitted by incandescent 
1) CAMPBELL, Astroph. Journ. XI, p. 229. 
