Malus, Stephen Louis

, a distinguished mathematician, philosopher, and military engineer, was born at Paris July 23, 1775. His first education was principally directe’d to classical and polite literature, and at seventeen years of age he composed a tragedy in five acts, called “The Death of Cato.” These pursuits, however, did not prevent him from a study apparently not very compatible, that of the mathematics; for at the above age he passed an examination which gained him admittance into the school of engineers. After having distinguished himself there by his genius for analysis, he was about to leave it in quality of officer of military engineers, but was rejected on political grounds, and as this repulse deprived him of all hope of promotion there, he repaired to the army in the north, where he was incorporated in the 15th battalion of Paris, and was employed as a common soldier in the fortifications of Dunkirk. The officer of engineers, who superintended those works, perceiving that Malus was deserving of a better station, represented his merits to the government, and he was recalled and sent to the Polytechnic school, where he was soon appointed to the analytic course in the absence of M. Monge. Being now re-established in his | former rank at the date of his first nomination, he succeeded almost immediately to that of captain, and was employed at the school at Metz as professor of mathematics.

It was at this period (1797), that his military career commenced, and in the army of the Sambre and Meuse he was present at the passage of the Rhine. The same year he formed an attachment to the lady who afterwards became his wife. She was the daughter of the chancellor of the university of Giessen; but honour and duty prevented him from then realising his wishes. He was obliged to embark for Egypt, and assisted at the battles of Chebreis, and of the Pyramids. He was chosen member of the Institute of Cairo, but his life was too active and busy to allow him to indulge his taste for the sciences. One only occasion presented itself, of which he knew how to take advantage. In a reconnoitre on which he was ordered along with M. Lefevre, engineer of bridges and causeways, he had the satisfaction to discover a branch of the Nile, hitherto unknown to travellers, and to draw a description and map of a country where no Frenchman had penetrated since the crusades; and the memoir which he wrote on this subject forms part of the first volume of “La Decade Egyptienne.” But it was as a military engineer that he principally distinguished himself during this memorable expedition, particularly during the dangers of all kinds which attended him in Syria, and at the siege of El-Hariscb, and Jaffa, where he filled the office of engineer. After the capture of this town, he received orders to repair the fortifications, and to establish military hospitals. Here he was attacked by the plague, of which he had the good fortune to cure himself without any foreign assistance. Scarcely recovered, he hastened to Damietta on business, and from thence marched against the Turks who had landed at Lisbech; and was present at the battle of Heliopolis and Coraim, and at the siege of Cairo. After other movements, which will be found in the history of that expedition, he embarked at Aboukir, and arrived in France in Oct. 1801.

Although exhausted by so many fatigues, and by the dreadful diseases which had undermined his constitution, he did not neglect his promise to his mistress, but married her soon after his arrival, and their union, though short, was happy. About the time of his marriage, Malus gained new celebrity by a work in which be treated all the | optical questions which depend on geometry, and in which he expounded and calculated all the phenomena of reflection and refraction, and followed the ray of light through all its various courses. This production called the attention of the learned to the phenomenon of double refraction, which had occupied Huygens and Newton; and hopes were entertained of obtaining an explanation of a fact which had defied the penetration of the greatest geniuses. The Institute of France made it the subject of a prize, which ]VIalus gained, and shewed that to the analytical knowledge of which he had given proofs in his first work, he could unite the patience, the skill, and the sagacity, which constitute a great philosopher. By very nice experiments he discovered a remarkable and totally unknown property of light, that is, the resemblance between the loadstone and a particle of light, the latter of which he found to acquire polarity and a determined direction. This success opened the doors of the Institute to him, where he supplied the place of a philosopher whose name had been immortalized by a brilliant discovery (Montgolfier).

Malus was a member of the legion of honour, and under director of the fortifications at Antwerp in 1804; underdirector of the barracks in the department of the Seine, in 1809; member of the committee of fortifications, and major of engineers, in 1810. In 1811 he was second in command, director of the studies of the Polytechnic school, in which he performed for several years, to the satisfaction of the directors and pupils, the arduous duties of examiner. These various occupations did not prevent him from continuing the ingenious experiments on which his fame was to be chiefly founded, and which procured him the Copley niedal from our royal society.

The activity of Malus was equal to so many different pursuits. Though he carried in his habit the seeds of that severe illness which was so soon to terminate his life, scarcely a week elapsed without his submitting to the Institute new fruits of his researches and his name being attached to the phenomenon of polarised light, which he discovered, all future discoveries of this kind must recall the remembrance of the philosopher who first opened this new road, and who, if he had lived, would have probably completed the theory of light. He died February 24th, 1812, in the thirty-seventh year of his age, a loss which cannot be sufficiently deplored, as his learning, his genius, | and indefatigable industry, afforded every hope that length of years would have added to his discoveries, and extended the boundaries of science. His discovery of the polarisation of light by oblique reflection is perhaps the most important that optics has received since the discovery of the achromatic telescope. 1


Notice historique par M. le Chevalier Delambre, road at the Institute of France, Jan. 3, 1814 and ebligingly communicated by Dr. Kelly of Finsburysquare.