12 REPORT— 1905. 
distributed throughout the globe. The forces called into play by these elec- 
trical interactions are clearly very complicated, and you will not be sur- 
prised to learn that Thomson found himself compelled to limit his detailed 
examination of the model atom to one containing about seventy corpuscles. 
It is indeed a triumph of mathematical power to have determined the 
mechanical conditions of such a miniature planetary system as I have 
described. 
It appears that in general there are definite arrangements of the 
orbits in which the corpuscles must revolve, if they are to be persistent 
or stable in their motions. But the number of corpuscles in such a com- 
munity is not absolutely fixed. It is easy to see that we might add a 
minor planet, or indeed half a dozen minor planets, to the solar system 
without any material derangement of the whole; but it would not be 
possible to add a hundred planets with an aggregate mass equal to that 
of Jupiter without disorganisation of the solar system. So also we might 
add or subtract from an atom three or four corpuscles from a system 
containing a thousand corpuscles moving in regular orbits without any 
profound derangement. As each arrangement of orbits corresponds to 
the atom of a distinct element, we may say that the addition or subtrac- 
tion of a few corpuscles to the atom will not effect a transmutation of 
elements. An atom which has a deficiency of its full complement of cor- 
puscles, which it will be remembered are negative, will be positively 
electrified, while one with an excess of corpuscles will be negatively elec- 
trified. I have referred to the possibility of a deficiency or excess of 
corpuscles because it is important in Thomson’s theory ; but, as it is not 
involved in the point of view which I wish to take, I will henceforth only 
refer to the normal or average number in any arrangement of corpuscles. 
Accordingly we may state that definite numbers of corpuscles are capable 
of association in stable communities of definite types. 
An infinite number of communities are possible, possessing greater or 
lesser degrees of stability. Thus the corpuscles in one such community 
might make thousands of revolutions in their orbits before instability 
declared itself ; such an atom might perhaps last for a long time as esti- 
mated in millionths of seconds, but it must finally break up and the 
corpuscles must disperse or rearrange themselves after the ejection of 
some of their number. We are thus led to conjecture that the several 
chemical elements represent those different kinds of communities of cor- 
puscles which have proved by their stability to be successful in the 
struggle for life. If this is so, it is almost impossible to believe that the 
successful species have existed for all time, and we must hold that they 
originated under conditions about which I must forbear to follow Sir 
Norman Lockyer in speculating.! 
But if the elements were not eternal in the past, we must ask 
whether there is reason to believe that they will be eternal in the 
! Inorganic Evolution, Macmillan, 1900. 
