Evolution and Devolution of the Elements. 21 
Finally, the fundamental proposition is dealt with mathe- 
matically from an entirely different point of view and the 
same result obtained. 
In conclusion I wish to express my thanks to Prof. J. J. 
Thomson and to Mr. G. F. C. Searle for several valuable 
criticisms and suggestions. 
Cambridge, England, 
August 14th, 1907. 
II. The Evolution and Devolution of the Elements. 
By A. C. and A. E. Jessup *. 
[Plate VII.] 
rpHE hypothesis that the elements are different forms of 
J- one original substance was first formulated in modern 
times by Prout, and though his idea that hydrogen was that 
substance has since been shown to be incorrect, yet modern 
theories have given us, in the corpuscle, a body which may 
well be the root basis of all matter. 
The recent researches of M. and Mme. Curie, Sir William 
Ramsay and Mr. Soddy, Professor Rutherford and others, 
have brought to light the fact that some of the elements are 
undoubtedly degrading into simpler forms of matter. But 
when we look for a reversal of this process on the earth, it is 
not apparent. In other words, we have as yet found no 
indications that elements with low atomic weight are changing 
into other elements with a higher atomic weight, that is, we 
have no proof of inorganic evolution. But when we turn 
our attention to the heavens, the case is altered, and it is 
entirely upon astrophysical observations that the ideas of 
evolution we are about to bring forward are based. 
It was originally our intention to give these observations 
in full, but it has appeared advisable to give in the present 
paper only such of them as are essential for an understanding 
of what follows. 
Spectroscopic evidence shows us that the nebula? contain 
but few elements, all of which are in a highly attenuated 
form. The only two which have been recognized on the 
earth are hydrogen and helium, and the atomic weights of 
these are less than those of any other elements with which 
we are acquainted. 
As the nebula becomes more compact, and assumes the 
form of a star, more and more complex elements appear, such 
* Communicated by Sir William Ramsay, K.C.B., F.R.S. 
8S2o 
