208 Proceedings of the Boyal Society 
altered, it is not the impulse on the liquid which is given, hut de- 
finite kinematic relations are laid down to which the impulsive 
motion must be subject. In such a case. Professor Thomson has 
shown that the kinetic energy which has been thus generated is 
a minimum ; and it is for this theorem that the Prize has been 
awarded, — a theorem which not only affords a direct and simple 
mode of dealing with questions of more than ordinary difficulty, 
but which is itself an extremely singular and valuable property of 
Motion. 
The researches of Professor Thomson, to which we have referred, 
are of too recondite a nature to he generally appreciated. The re- 
sults of abstract Science have ever failed to excite the notice, or 
call forth the gratitude, of the State. The question of practical 
use — the cui hono of ignorance — is put every day by educated men 
in high and responsible positions, to whom are confided the mightiest 
interests of the nation. History and experience might have taught 
them, had they been capable of learning, that abstract Science is 
the life and soul of Industry, and that its successful cultivators are 
the true benefactors, not of their country only, hut of their species. 
The discoveries of our eminent colleague, and even the very abstract 
property of motion, to which we have attached so special a value, 
must, like all similar revelations, find invaluable applications to the 
material interests of society. 
I should be doing injustice, however, to Professor Thomson were 
I to characterise his researches as wholly abstract and transcen- 
dental. The important conclusions which he obtained from the 
Theory of Induction in submarine Telegraphs, have found a valu- 
able practical application in the Patent Instruments for reading 
and receiving messages, which he so successfully employed on the 
submarine cable across the Atlantic ; and v/hen that great work is 
completed, his name will he associated with the noblest gift that 
Science ever offered to Civilisation. By his delicate Electrometers, 
his Electric Spark Eecorder, and his Marine and Land Eeflection 
G-alvanometers, he has provided the world of thought with the 
finest instruments of observation and research ; and the world of 
action with the means of carrying the messages of commerce and 
civilisation which have yet to cross the uncabled oceans that sepa- 
rate the families of the earth. 
