174 FRESNEL. 
gance and with grace. Also I could not but persuade 
myself that the indulgence of the Academy presaged in 
some degree that with which the public would deign to 
honour me; otherwise could I have dared to make an 
inexperienced voice heard here, after the eloquent inter- 
preter whom we have just lost, and by the side of him 
whom we have the happiness still to possess ? 
I hasten, moreover, to explain that this éloge departs 
from the ordinary form. I shall even ask the favour of its 
being looked upon as simply a scientific memoir, in which, 
taking occasion from the labours of our late associate, I 
have the opportunity of examining the progress which 
has been made in our times in several of the most impor- 
tant branches of optics. At an epoch when the courses 
of lectures at the Collége de France, of the Faculté de 
Paris, of the Jardin du Roi are attracting so great a 
concourse of auditors, it has occurred to me that the 
Academy of Sciences might directly address itself to the 
public (that friend of our studies, showing its good will 
by so numerous an attendance at our meetings) on some 
of the various questions with which we are specially occu- 
pied. At the same time this is but a simple attempt of 
my own on which I should wish to be enlightened; the 
critic will find me docile. I hope, however, that the satis- 
faction of becoming initiated in a few minutes into the 
most curious discoveries of one century, may appear a 
sufficient compensation for the inevitable tediousness 
which so many minute details must cause. 
For my own part, the indulgence on which I count 
will not prevent my making every effort to render myself 
clear. Fontenelle, on a similar occasion, asked of his 
auditory (I quote his own expression) “the same atten- 
tion which they would necessarily give to the romance of 
