MALUS, Etienne Louis (1775-1812) - Théorie de la double réfraction de la lumière dans les substances cristallisées. Pargi: Garnerey, Baudoin, 1810. First edition of the prize winning work that contains the polarization theories of the French physicist Etienne Louis Malus. The scientist discovered that light, when reflected, becomes partially plane polarized; i.e., its rays vibrate in the same plane. His observation led to a better understanding of the propagation of light and his is best known for Malus's law, giving the resultant intensity, when a polariser is placed in the path of an incident beam. Uncut copy. 4to (271 x 218mm). Half title, 3 engraved folding plates at end (some spotting and few leaves lightly browned). Original paper boards, paper label on spine, uncut (some wear to paperlabel). DSB.