MALUS, ETIENNE Louis, 1775-1812, b. Paris; educated at the school of military engineers, but falling, under the suspicion of the revolutionary government, was dis missed. While serving as a private soldier at Dunkirk, he attracted the attention of Lepere, director of the fortifications there, who procured him an appointment to the Ecole Polytechnique. Here he pursued the study of mathematics, and especially of the mathematical theory of optics. Appointed to the engineers, he entered the army of the Sambre and Meuse, and witnessed the passage of the Rhine, and the engagements at Altenkirch and Ukratz. He was attached to the Egyptian expedition, and after the cap ture of Jaffa, was engaged in the restoration of its fortifications, and the construction of military hospitals. Me fortified Damietta, was present at the siege of Cairo, and after the surrender to the English, came back to France in 1801. He now took charge of the fortifications at Antwerp and Strasbura., at the same time carrying on his scientific researches. His Traite d' Optique, published in 1810, treats of the refraction and reflection of light, and contains experiments in regard to the reflection of light in transparent media. In 1908 the French institute offered a prize for the best paper on double refraction in crystals. Mains competed for this prize, and in the course of his experiments discovered
the phenomenon known as the polarization of light. He advanced the theory that par ticles of light have poles, and that on entering a doubly-refractina- crystal, some of the particles forming one of the rays may be so arranged as to be tTansunitted through it, while the particles which should have formed the other ray may be so arranged as to prevent the transmission in certain directions. The discovery of these phenomena intro duced a new division of physical optics. Maks published an account of them in the .31emoirs of the institute, which at once elected him to its membership; and the English royal society gave him the Rumford medal, though France and England were then at war. In 1810 he published his T Iteorie dela Double Refraction dela 1,1uniere dans les Substances Cristallisees, and the next year he wrote a couple of papers on some phenomena of polar ized light. He was appointed examiner in physics at the .Ecole Polyteclinique, and was about to be appointed director of its studies when he died.