“ By the use of two plane mirrors of metal, forming with each other an angle of nearly 180°, he avoided the diffraction caused in the experiment of F. M. Grimaldi (1618–1663) on interference by the employment of apertures for the transmission of the light, and was thus enabled in the most conclusive manner to account for the phenomena of interference in accordance with the undulatory theory. With D. F. J. Arago he studied the laws of the interference of polarized rays. ”

“ His early progress in learning was slow, and when eight years old he was still unable to read. At the age of thirteen he entered the École Centrale in Caen, and at sixteen and a half the École Polytechnique, where he acquitted himself with distinction. ”