i879-] 
British Association. 
635 
tions which would refer many very different phenomena to a 
common source. But in this very charm there is undoubtedly a 
danger, and we must be all the more careful lest it should exert 
an influence in arresting the progress of truth, just as at an 
earlier period traditional beliefs exerted an authority from which 
the mind but slowly and with difficulty succeeded in emancipating 
itself. 
But have we, it may be asked, made in all this one step forward 
towards an explanation of the phenomena of consciousness or 
the discovery of its source ? Assuredly not. The power of con- 
ceiving of a substance different from that of matter is still beyond 
the limits of human intelligence, and the physical or objective 
conditions which are the concomitants of thought are the only 
ones of which it is possible to know anything, and the only ones 
whose study is of value. 
We are not, however, on that account forced to the conclusion 
that there is nothing in the universe but matter and force. The 
simplest physical law is absolutely inconceivable by the highest 
of the brutes, and no one would be justified in assuming that man 
had already attained the limit of his powers. Whatever may be 
that mysterious bond which connects organisation with psychical 
endowments, the one grand fadT — a fadt of inestimable import- 
ance — stands out clear and freed from all obscurity and doubt, 
that from the first dawn of intelligence there is with every ad- 
vance in organisation a corresponding advance in mind. Mind 
as well as body is thus travelling onwards through higher and 
still higher phases ; the great law of Evolution is shaping the 
destiny of our race ; and though we may at most but indicate 
some weak point in the generalisation which would refer con- 
sciousness as well as life to a common material source, who can 
say that in the far-off future there may not yet be evolved other 
and higher faculties from which light may stream in upon the 
darkness, and reveal to man the great mystery of Thought ? 
The first Evening Discourse was by Mr. Crookes, F.R.S., 
“ On Radiant Matter the second by Prof. Ray Lankester. 
F.R.S., “ On Degeneration;” while the Saturday evening 
Ledture to Working Men was delivered by Mr. W. E. 
Ayrton, the subiedt being “ The Transmission of Power by 
Eledtricity.” 
Mr. Crookes’s discourse was illustrated by experiments 
on the movements of molecules in high vacua, some of which 
were recently described in the “ Monthlyjournal of Science.” 
According to the best authorities, a bulb 13*5 centimetres in 
diameter contains more than 1,000000,000000,000000,000000 
(a quadrillion) molecules. Mr. Crookes showed that when 
exhausted to a millionth of an atmosphere there are still a 
