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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 light 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 

 atomic structure of the crystal itself is revealed and the motion of the atoms 

 outlined. The imporatnce of this discovery in relation to thermal effects 

 and heat emissions accompanying chemical reactions and rearrangements 

 can 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 topic; 

 while he sets forth the new idea involved he retains 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 — 27 gm. em. /sec, an exceedingly small quantitj r . 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 

 Avhere the wave theory fails to carry us any farther and that whereas it serves 

 us Avell in explaining difficulties of elementary problems it docs not carry 

 us to an ultimate solution. We may conclude 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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