264 FRESNEL. 
covered, important applications rise up, as if by enchant- 
ment, out of experiments which, until then, would seem 
likely to remain for ever among the number of abstract 
speculations. A fact which no direct utility had as yet 
recommended to the attention of the public becomes, per- 
haps, the step on which a man of genius supports himself 
to climb up to those primary truths which change the 
whole face of science, whether for creation of some eco- 
nomical moving power, which all manufacturing arts will 
henceforth adopt, and of which not the least merit is that 
of delivering thousands of operatives from overwhelming 
toils which assimilated them with the brutes, ruined their 
health, and brought them to a premature death. If to 
fortify these reflections examples may be thought neces- 
sary, I should feel no other embarrassment than that of 
too wide a choice. But here there is no necessity to 
enter on such details ; for to all the theoretical researches 
already mentioned, Fresnel has added an important labour, 
having an immediate practical application, which will cer- 
tainly place. his name among those of the benefactors of 
the human race. This work, every one knows, had for 
its object the improvement of light-houses. I will pro- 
ceed to trace the outline of its progress, and shall thus 
have finished the sketch which I proposed to offer you of 
the brilliant scientific career of our late colleague. 
Persons unacquainted with nautical matters are usually 
seizéd with a sort of fear when the vessel which carries — 
them, at a distance from continents or islands, has no 
other witness of its progress than the stars and the waves. 
A view of any coast the most barren, the most rocky, the 
most inhospitable, dissipates, as if by enchantment, those 
undefined fears which their absolutely isolated position 
had inspired, while, to the experienced navigator, it is 
