ELECTRIC RADIATIONS—BRAGG. 207 
end might be incorporation with an atom traversed. Professor 
Rutherford has suggested to me that such a fate may befall the a 
particle at the end of its range. On this view it would be possible 
for a portion of a disintegrating atom to break away, to pass over 
an appreciable distance, and finally to become part of another atom, 
the atomic weight of which would be thereby increased. Internal 
atomic energy might be transferred at the same time. For if we 
suppose that it is possible for some of the internal energy of an atom 
to be set free, and recent discoveries seem to compel the supposition, 
then we must also consider it possible for atoms to withdraw energy 
from circulation and add it to their internal store. If, therefore, 
the handing of neutral pairs from one atom to another is a process 
which actually occurs, then matter and energy may be continually 
transferred from atom to atom without our being aware of it: the 
whole operation may take place in a world apart. We can not follow 
it by radioactive tests, for the ionization is so feeble; nor chemically, 
because the rate of atomic change is so slow; nor thermally, because 
the energies appear at no stage in tangible form. 
Since the properties of y rays are amongst the properties of X rays, 
an hypothesis which will suit one form of radiation will also so far 
suit the other. But we know much more about the latter form of 
radiation than we do about the former. It is of interest, therefore, to 
consider the extent to which our additional knowledge can be fitted to 
- a neutral pair hypothesis. It is true, of course, that the ether pulse 
theory has been most ably developed, and is now widely accepted. 
Nevertheless the evidence for it is all indirect: and indeed some of it 
is, I think, a little overrated. It is quite possible that ether pulses 
may not, after all, constitute the bulk of Rontgen radiation. If, 
therefore, there is anything to be said in favor of any other hypoth- 
esis, it seems right that it should be said and considered. 
Let us therefore for the moment suppose the X rays to consist 
mainly of a stream of neutral pairs. 
We have at once an explanation of the absence of deflection in 
electric and magnetic fields and of regular reflection and refraction. 
There should be great penetration, whose amount might vary with 
the moments of the pairs, or the velocity, if the latter were a variable. 
We can understand that a pair which struck a hght and yielding 
atom might be returned unchanged; yet if it struck a heavier and 
more resisting atom it might be disarranged so as to acquire a greater 
moment, and thus to become a better ionizer, but more readily ab- 
sorbed ; or it might be shattered altogether, giving rise to a secondary 
ray of the cathode type. The softer the ray, i. e., the greater the 
moment of the pair, the more readily might this be done, and the 
