6 THE PRESIDENTIAL ADDRESS. 
Board of Trade, on miners’ lamps for the Home Office and on motor- 
car head-lamps for the Ministry of Transport, and on the lighting 
of the National Gallery and the Houses of Parliament. Important 
work has been done on the forms of ships, on the steering and 
manceuvring of ships, on the effect of waves on ship resistance, on the 
interaction between passing ships, on seaplane floats, and on the 
hulls of flying-boats. 
It is also actively engaged in the study of problems connected with 
aviation, and has a well-ordered department for aerodynamical research. 
It can already point to a long and valuable series of published re- 
searches, which are acknowledged to be among the most important 
contributions to pure and applied physics which this country has made 
during recent years. 
I may be pardoned, I hope, for another personal reference, if I 
recall that it was at the Edinburgh meeting, under Lord Kelvin’s presi- 
dency, fifty years ago, that I first became a member of this Association, 
and had the honour of serving it as one of the secretaries of its chemical 
section. Fifty years is a considerable span in the life of an individual, 
but it is a relatively short period in the history of science. Nevertheless, 
those fifty years are richer in scientific achievement and in the impor- 
tance and magnitude of the utilitarian applications of practically every 
branch of science than any preceding similar interval. The most 
cursory comparison of the state of science, as revealed in his compre- 
hensive address, with the present condition of those departments on 
which he chiefly dwelt, will suffice to show that the development has 
been such that even Lord Kelvin’s penetrative genius, vivid imagina- 
tion, and sanguine temperament could hardly have anticipated. No 
previous half-century in the history of science has witnessed such 
momentous and far-reaching achievements. In pure chemistry it has 
seen the discovery of argon by Rayleigh, of radium by Madame Curie, 
of helium as a terrestrial element by Ramsay, of neon, xenon, and 
krypton by Ramsay and Travers, the production of helium from radium 
by Ramsay and Soddy, and the isolation of fluorine by Moissan, 
These are undoubtedly great discoveries, but their value is enormously 
enhanced by the theoretical and practical consequences which flow 
from them. 
In applied chemistry it has witnessed the general application of the 
Gilchrist-Thomas process of iron-purification, the production of calcium 
cyanamide by the process of Frank and Caro, Sabatier’s process of 
hydrogenation, a widespread application of liquefied gases, and Haber’s 
work on ammonia synthesis—all manufacturing processes which have 
practically revolutionised the industries with which they are con- 
cerned. ; 
In pure physics it has seen the rise of the electron theory, by 
