TEMPERATURE AND STRUCTURE OP THE SUN. 101 
courage. On the basis of Julius’ theory, I believe that this 
phenomenon is due to (he different amount of anomalous 
dispersion of the different waves emitted by one and the 
same element. 
Thus we see that, starting out from questions of purely 
scientific significance like black radiation or, what is the same 
thing, the determination of the constant S in Kirchhoff’s law 
we have succeeded in answering questions of 
thoroughly practical importance. Much still remains to be 
done, and I venture to express the hope that by my address 
new problems may have been suggested to you, the solution of 
which will be found in your admirable institutions and labora- 
tories at Washington. 
