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strikes us that in the region 6000—4000 A this decrease of intensify 
presents an oscillation. It is noteworthy that the maximum of energy 
of the sun’s radiation lies at the same place in the spectrum. 
Lr 
100 5 
90 53 
80 82.5 
70 
93 
60 
50 
40 
oO 
3000 7000 7000 5000 400A 
Fig. 1, 
(ABBor’s observations ranged from 21000 A to 3800 A; the part 
from 21000—9000 A has, however, been omitted in the figure, 
because the curves do not present an irregular course there, but 
gradually approach the line J, = 100 towards 21000 A). 
To account for this decrease of intensity towards the limb many 
investigators have considered the sun as a self-luminous uniformly 
radiating core, surrounded by a strongly absorbing atmosphere. 
Now the state in the sun’s atmosphere must naturally be stationary 
on the average: the quantity of energy that the atmosphere absorbs, 
must be radiated again, even though it be in another form, and 
half must be radiated towards the outside. Now it has appeared 
convincingly from the observations of the annular eclipse of April 
17» 1912 5) that of the total quantity of energy that the earth receives 
from the sun, at most one thousandth part can originate from 
the sun’s atmosphere. It is, therefore, impossible that the absorption 
should be the chief cause of the diminution of intensity towards 
the limb. 
1) W. H. Junius. These Proc. 15, 1451. 
