CAUCHY, ko'shiY. AUGUSTIN Louts (178/ 1857). A French mathematician. lle was born in Paris, and was edueated at the Ecole Poly technique. In 1810 he went to Cherbourg, in the capacity of an engineer. hut his health failing, he meturned to Paris in 1813, renounced engineering, and chose pure science for his life work. his if 'nre,ire stir I r theorie des oirdcs was crowned by the Institute in 1813• and in 1816 he became a member of the Academy of Sciences. Later he be came professor at the Polytechnic School. In 1830 he refused to take the oath required by Louis Philippe, and went into voluntary exile. During his stay abroad he held for a short time the chair of mathematics in Turin, and later (1834) went to Prague as tutor of the Comte de Cham bord. He returned to France in 1837. but his political views were such as to bar him from the higher professorships until the advent of the Government of 1848. In that year Cauchy was made professor of mathematical astronomy at the '4orbonne, a chair which he held, with a brief interruption, until his death. In politics Cauchy was a Legitimist. lie was known as a man of piety and was a defender of the -Jesuits.
The works of Cauchy occupy a leading place in science. All parts of pure and applied
mathematics, as geometry, algebra, the theory of numbers. integral calculus, mechanics, as tronomy. and mathematieal physics. are indebt ed to his discoveries. He verified the periodic ity of elliptic functions, gave the first impetus to the general theory of contributed to determinants (q.v.). and laid the foundation for the modern treatment of the convergence of infinite series (1.v.). lie emphasized the imag inary as a fundamental. not subsidiary, quan tity. perfected the method of integration of linear differential equations (see CALCULUS), advanced the theory of substitutions, invented the calculus of residues, and, hr general. was one of the leaders of the Nineteenth Century• in infusing vigor into analysis. The propagation of light and the theory of elasticity also received his attention.
Consult: VaIsom La Vie CI les travaus de Cauchy (Paris. 1868) : Terquem, "Analyse des travaux de Cauchy," in the Nourellcs annales de nualu'rnatiancs ( Paris, 1837), Les wu•rcs corn 1 es d'.1 uy us( in Cauchy (Paris, I SS2 1901) were published under the direction of the Academy of Sciences.