President's Address. 
e57 
and to ensure to his discourses a ready and speedy publication. This, 
I may surely promise, the Eoyal Irish Academy will be always glad 
and proud to do. 
Turning now from Pure to Applied Mathematics, I may repeat 
something which I have before said. I may repeat (I am sorry to say) 
that here, as in Pure Mathematics, the history of the Academy for 
some time past does not show that intellectual activity which we 
could wish to see. Part of this effect is probably due to a cause which 
I have noticed before — general decline of scientific interest in a 
subject which once occupied much of our attention here, namely, 
Molecular Mechanics, passing into Mathematico-Physical Optics. 
But after all due allowance for the operation of this cause, enough 
remains to cause us serious anxiety, lest, by neglect of ours, we should 
lose any opportunity of rendering to science a service which only 
a scientific society/ can render. Eor our function here is of much 
greater importance than in the case of Pure Mathematics. With the 
mathematician it is comparatively unimportant whether his discoveries 
be given to the world through the medium of a scientific society, or 
through the medium of a separate treatise. But with the mathematical 
physicist it is far from being unimportant. He is not — ^ught not to be 
at least — a solitary student. If he would have his theories to be some- 
thing more than mere mathematical speculations — if he would acquire 
for them the character of true, or even approximate, representations 
of ]N"ature — he must come among other scientific men, who are viewing 
the subject from a stand-point difi'erent from his own. He must correct 
his speculations by the practical knowledge of the experimentalist, 
content to modify every favourite theory to meet the hard requirements 
of reality — nay more, content, if need be, to surrender it altogether — to 
hear and obey the voice of I^ature, which tells him that he is pursuing 
an unreal phantom, sure to elude his grasp — which tells him that if he 
be indeed a worshipper of truth, he must give diligent heed that no 
symmetric beauty of the theory hide from him the one great question, 
Is it true. And there is nothing which will more efi'ectually correct 
the habit, so injurious to the progress of physical science, of adopting 
physical theories solely on account of their mathematical beauty, 
than free discussion of such theories by an experimentalist, with whom 
mathematical beauty counts for very little, and whose sole object 
is to inquire whether the theory presented to him be a faithful 
representation of nature. Hid we value such discussions solely in 
their character of destructive criticism, we could, even then, scarcely 
value them too highly for the service which they can render to the 
mathematical physicist, by constantly reminding him that he has to 
deal with realities, not mere abstractions, however beautiful, and thus 
saving him from the expenditure of time, and labour, and genius, upon 
that which is — physically — unprofitable. 
But this is not the only service which the experimental philosopher 
can render to the mathematical physicist. He can suggest as well as 
correct. If he can check the growth of weeds, he can also save the 
R. I. A. PROC. — VOL. I., SER. II., SCIENCE. I 
