PRESIDENT’S ADDRESS. 27 
whole field is open for discovery; it is even possible to investigate the 
changes in shape of an electron—appallingly minute though it is— 
as it approaches the speed of light; and properties belonging to the 
Ether of Space, evasive though it be, cannot lag far behind. 
Speaking as a physicist, I must claim the Ether as peculiarly our own 
domain. The study of molecules we share with the chemist, and matter 
in its various forms is investigated by all men of science, but a study 
of the ether of space belongs to physics only. I am not alone in feeling 
the fascination of this portentous entity. Its curiously elusive and 
intangible character, combined with its universal and unifying per- 
meance, its apparently infinite extent, its definite and perfect properties, 
make the ether the most interesting as it is by far the largest and most 
fundamental ingredient in the material cosmos. 
As Sir J. J. Thomson said at Winnipeg :— 
‘The ether is not a fantastic creation of the speculative 
philosopher ; it is as essential to us as the air we breathe... . 
The study of this all-pervading substance is perhaps the most 
fascinating and important duty of the physicist.’ 
Matter it is not, but material it is; it belongs to the material 
universe and is to be investigated by ordinary methods. But to say 
this is by no means to deny that it may have mental and spiritual 
functions to subserve in some other order of existence, as Matter has 
in this. 
The ether of space is at least the great engine of continuity. It 
may be much more, for without it there could hardly be a material 
universe at all. Certainly, however, it is essential to continuity; it is 
the one all-permeating substance that binds the whole of the particles 
of matter together. It is the uniting and binding medium without 
which, if matter could exist at all, it could exist only as chaotic and 
isolated fragments: and it is the universal medium of communication 
_ between worlds and particles. And yet it is possible for people to deny 
its existence, because it is unrelated to any of our senses, except sight,— 
and to that only in an indirect and not easily recognised fashion. 
To illustrate the thorough way in which we may be unable to detect 
what is around us unless it has some link or bond which enables it to 
make appeal, let me make another quotation from Sir J. J. Thomson’s 
Address at Winnipeg in 1909. He is leading up to the fact that even 
single atoms, provided they are fully electrified with the proper atomic 
charge, can be detected by certain delicate instruments,—their field of 
force bringing them within our ken—whereas a whole crowd of 
_ unelectrified ones would escape observation. 
‘The smallest quantity of unelectrified matter ever detected 
is probably that of neon, one of the inert gases of the atmosphere. 
