272 H.. Draper— Oxygen in the Sun. 
an unfortunate position, but I think it is a truly scientific posi- 
tion, Now, taking the position of a sceptic, one has to exam- 
ine these photographs and look to whether Dr. Draper has 
own the coincidences as Mr. Ranyard asserts; if not, his 
probabilities fall to the ground. In more than one instance I 
find an oxygen line opposite a broader bright space in the solar 
spectrum, which appears of identically the same brightness in 
its whole breadth. If the broader space consists of two or more 
bright lines, as has been suggested, we have two difficulties to 
contend with; in the first place we have to show that there are 
other substances which would give lines corresponding to the 
unoceupied breadth of the interspace, and in the second place 
we have the fact that these lines are undistinguishable in bright- 
ness from the oxygen lines. Again, each of the oxygen lines 
is fuzzy at the edges, and as there is nothing analogous in the 
solar spectrum, we have to suppose that the fuzzy edges are cut 
off by adjacent dark lines. Now, if we are to make use of 
probabilities, I would ask what is the probability of a pair of 
dark lines falling in every case exactly at the edges of an oxy- 
gen line? We must also take into account the fact that former 
physicists have failed to identify any of the bright lines of oxy- 
gen with dark lines in the solar spectrum, and therefore we 
start with the fact that none of the oxygen lines can fall oppo- 
Ste, to dark lines. 
earth affords evidence that the solar system has been in exist- 
ence for more than 20,000,000 of years, whereas, if the Sun 
2 giving out energy as at present for 20,000,000 years, 
we know that it cannot have derived it from shrinking from 
Stars, but rather think that it points to. the fact that the real 
mass of the Sun lies very much within the photosphere, and 
that if there.is any solid or liquid nucleus, it is only at a depth 
of many thousands of miles below the photosphere. If that is 
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