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of light waves except in regard to their wave length, these being approximately 
1/10000 the length of ultra-violet waves; these and the foregoing phenomena 
accompanying the ionization and dissociation of various gases; the disinte- 
gration of radioactive substances have given the champions of the undu- 
latory theory of light some reason for alarm; the phenomena of interference 
was formerly considered as explainable only in the hight of the wave theory, 
but the behavior of the X-rays when examined for interference effects in 
crystals seems to pave the way for a revision of this. Not only can the 
wave lengths of X-rays be measured by the method suggested but the 
atomie structure of the crystal itself is revealed and the motion of the atoms 
outlined. The imporatnee of this discovery in relation to thermal effects 
and heat emissions accompanying chemical reactions and rearrangements 
ean hardly be overestimated. 
As to the seriousness of the attempts to get at the ultimate constitution 
of light and heat centers and thereby gain a clearer knowledge of the 
mechanism of radiation, we have but to note the trend of thought as pre- 
sented in recent papers read before the British Association for the Advance- 
ment of Science. At the recent Birmingham meeting of this association, 
a vigorous discussion arose as to the fundamentals involved in this ques- 
tion of radiation. At the meeting, J. H. Jeans, F. R. S., gave a very interest- 
ing and comprehensive summary of the facts relating to this fruitful topie; 
while he sets forth the new idea involved he retain. faith in the truth of 
Maxwell’s equations, but suggests that these equations can be made of 
more general application by the addition of the expression representing 
the unit quantities employed by Planck in his development. These quan- 
tities being respectively E and h. The magnitude of H has been determined 
to be 6.415 x 10 —% gm. em./sec., an exceedingly small quantity. We 
might quote from Einstein in support of the quantum theory: he approached 
the problem from the standpoint of the theory of relativity. It may be 
necessary to revise our ideas of an all-pervading ether so essential to the 
working of the undulatory theory. We are just beginning to realize that 
we may have arrived at a point in our knowledge of light and heat centers 
where the wave theory fails to carry us any farther and that whereas it serves 
us well in explaining difficulties of elementary problems it does not carry 
us to an ultimate solution. We may conelude that as there are unmis- 
takeable evidences derived from different sources that the undulatory theory 
fails to give satisfactory solution to many of the newer problems that have 
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