Gauss,

Gauss, JOHANN KARL FRIEDRICH, German mathematician, born at Brunswick, 30th April 1777, in 1801 published an important work on the theory of numbers and other analytical subjects, Disquisitiones Arithmeticae. Shortly afterwards his attention was attracted to astronomy; and he invented, and used in brilliant fashion, new methods for the calculation of the orbits of planets, comets, &c. The fruits of his researches in this department appeared, two years after his appointment as professor of Mathematics and director of the observatory at Göttingen, in his Theoria Motus Corporum Coelestium (1809). He also laboured with equally brilliant success in the science of geodesy, being appointed by the Hanoverian government to conduct the trigonometrical survey of the kingdom and to measure an arc of the meridian. Whilst engaged in this work he invented the instrument then called heliotrope (see HELIOGRAPHY). Later in life (in 1843-46) he published a collection of valuable memoirs on surface geometry, in Ueber Gegenstände der höhern Geodäsie. In the meantime he had also begun to study the problems arising out of the earth's magnetic properties. In 1833 he wrote his first work on the theory of magnetism, Intensitas Vis Magneticae Terrestris; and in conjunction with W. E. Weber he invented the declination needle and a magnetometer. He was also mainly instrumental in founding a Magnetic Association, which published valuable papers, entitled Resultate (1836-39), including two by Gauss on the law of magnetic attraction. In applied mathematics he investigated the problems connected with the passage of light through a system of lenses, in Dioptrische Untersuchungen (1840). Besides the researches already mentioned he wrote papers or works on probability, the method of least squares, the theory of biquadratic residues, constructed tables for the conversion of fractions into decimals and of the number of classes of binary quadratic forms, and discussed hypergeometric series, interpolation, curved surfaces, and the projection of surfaces on maps, all of which, with others, are printed in the seven vols. of his collected works (Gött. 1863-71). Gauss died at Göttingen, 23d February 1855. See Lives by Sartorius von Waltershausen (2d ed. 1877) and Winnecke (1877).