1911 Encyclopædia Britannica/Ampère, André Marie
AMPÈRE, ANDRÉ MARIE (1775–1836), French physicist, was born at Polemieux, near Lyons, on the 22nd of January 1775. He is generally credited as one of the main discoverers of electromagnetism. The ampere unit of measurement of electrical current is named after him. He took a passionate delight in the pursuit of knowledge from his very infancy, and is reported to have worked out long arithmetical sums by means of pebbles and biscuit crumbs before he knew the figures. His father began to teach him Latin, but ceased on discovering the boy's greater inclination and aptitude for mathematical studies. The young Ampere, however, soon resumed his Latin lessons, to enable him to master the works of Euler and Bernouilli. In later life he was accustomed to say that he knew as much about mathematics when he was eighteen as ever he knew; but his reading embraced nearly the whole round of knowledge—history, travels, poetry, philosophy and the natural sciences. When Lyons was taken by the army of the Convention in 1793, the father of Ampère, who, holding the office of juge de paix, had stood out resolutely against the previous revolutionary excesses, was at once thrown into prison, and soon after perished on the scaffold. This event produced a profound impression on his susceptible mind, and for more than a year he remained sunk in apathy. Then his interest was aroused by some letters on botany which fell into his hands, and from botany he turned to the study of the classic poets, and to the writing of verses himself. In 1796 he met Julie Carron, and an attachment sprang up between them, the progress of which he naively recorded in a journal (Amorum). In 1799 they were married. From about 1796 Ampère gave private lessons at Lyons in mathematics, chemistry and languages; and in 1801 he removed to Bourg, as professor of physics and chemistry, leaving his ailing wife and infant son at Lyons. She died in 1804, and he never recovered from the blow. In the same year he was appointed professor of mathematics at the lycee of Lyons. His small treatise, Considerations sur la theorie mathématique du jeu, which demonstrated that the chances of play are decidedly against the habitual gambler, published in 1802, brought him under the notice of J. B. J. Delambre, whose recommendation obtained for him the Lyons appointment, and afterwards (1804) a subordinate position in the polytechnic school at Paris, where he was elected professor of mathematics in 1809. Here he continued to prosecute his scientific researches and his multifarious studies with unabated diligence. He was admitted a member of the Institute in 1814. It is on the service that he rendered to science in establishing the relations between electricity and magnetism, and in developing the science of electromagnetism, or, as be called it, electrodynamics, that Ampère's fame mainly rests. On the 11th of September 1820 he heard of H. C. Ørsted's discovery that a magnetic needle is acted on by a voltaic current. On the 18th of the same month he presented a paper to the Academy, containing a far more complete exposition of that and kindred phenomena. (See Electrokinetics.) The whole field thus opened up he explored with characteristic industry and care, and developed a mathematical theory which not only explained the electromagnetic phenomena already observed but also predicted many new ones. His original memoirs on this subject may be found in the Ann. Chim. Phys. between 1820 and 1828. Late in life he prepared a remarkable Essai sur la philosophie des sciences. In addition, he wrote a number of scientific memoirs and papers, including two on the integration of partial differential equations (Jour. Ecole Polytechn. x., xi.). He died at Marseilles on the 10th of June 1836. The great amiability and childlike simplicity of Ampère's character are well brought out in his Journal et correspondance (Paris, 1872).