**Christian Wiener**'s father was a judge in Darmstadt, a town south of Frankfurt am Main and southeast of Mainz. Darmstadt had become a grand duchy in 1806 and, at the time Christian was born twenty years later, it was undergoing a period of rapid building of a new town under the first grand duke Ludwig I. Christian had a younger brother Jurgen Hambrecht Wiener who later moved to Vienna where he set up a butcher's shop and created the 'wiener sausage', as it is now sometimes called.

Christian attended the Gymnasium in Darmstadt, completing his studies in 1843. He then studied engineering and architecture at the University of Giessen, entering the university in the year he graduated from high school and taking four years for his studies. In 1847 he took the state examinations to qualify him to teach in secondary schools in Germany and in the following year of 1848 he became a teacher of physics, mechanics, hydraulics and descriptive geometry at the Technische Hochschule in Darmstadt. (It was called the Höhere Gewerbeschule at that time.) While teaching at the Höhere Gewerbeschule, Wiener was studying for his doctorate and he submitted his thesis *Bestimmte Lösung der Aufgabe über die Vertheilung eines Drucks auf mehr als drei Stützpunkte* Ⓣ on mechanics of particles and systems to the Justus-Liebig University of Giessen in 1850.

After obtaining his doctorate he was employed as a privatdozent at the University of Giessen where he began to teach. However, Wiener had ambitions to further his education and went to Karlsruhe where he studied mechanical engineering at the Technical University under Ferdinand Redtenbacher for a year. He returned to Giessen where he began teaching at the start of the academic year 1851-52. In 1852, however, he was appointed to the chair of descriptive geometry at the Technische Hochschule (Technical University) of Karlsruhe.

The Technische Hochschule had been founded in 1825 and was the first of its kind in Germany. Five years after Wiener arrived in Karlsruhe his son Hermann Wiener was born; Hermann went on to undertake his undergraduate studies under his father, then later wrote his habilitation thesis *Rein geometrische Theorie der Darstellung binärer Formen durch Punktgruppen auf der Geraden* Ⓣ at Karlsruhe under his father's guidance. Christian Wiener remained at the Technische Hochschule of Karlsruhe for the rest of his life, being three times elected as rector of the university.

Karlsruhe was the capital of the state of Baden. The state of Baden had seen a revolution led by Friedrich Hecker and Gustav von Struve four years before Wiener arrived at the capital Karlsruhe. A revolutionary government had been set up but it was suppressed by Prussian military forces in 1849 and restored Leopold as grand duke. Frederick I became grand duke in 1852, the year Wiener arrived, and continued in that role throughout the rest of Wiener's life. Wiener served the state of Baden in a number of ways, in particular as Oberschulrat. In Baden, public education was directed by the state and, as Oberschulrat, Wiener was head of the Educational Council.

Wiener worked on mathematics, physics, and philosophy. We shall say a little about his contributions in each of these areas in turn beginning with his mathematical contributions which were mainly on descriptive geometry. His chief work is a two volume book on geometry *Lehrbuch der darstellenden Geometrie* Ⓣ which supplements Chasles's work and contains important historical information [1]:-

Wiener extended work on descriptive geometry to physics and calculated the amount of solar radiation received at different latitudes during the varying lengths of days in the course of the year. This work was important in atmospheric studies and in climatic studies. Wiener was a skilled experimenter who was able to conduct experiments so that he obtained results which were remarkably accurate. This was demonstrated in his work on Brownian motion in which he was able to show that it was an "internal motion peculiar to the liquid state".Wiener treated the basic problems of descriptive geometry by a single method: a varied use of the principal lines of a plane. He also sought to simplify individual problems as much as possible and to find the easiest graphical solutions for them. He was not, however, concerned merely with graphical methods, of which he was a master. He was also interested in the problems and their solutions(such as shadow construction and brightness distribution), as well as in the development of the necessary geometric aids. For example, he used imaginary projection and developed a grid method that can be derived from the theory of cyclically projected point series.

Although Wiener wrote quite a number of works on philosophy, these did not have the impact of his mathematical and physical works. He was particularly interested in moral philosophy and wrote on topics such as free will and morality. As one might expect from an eminent scientist, Wiener defended scientific research against the opinions of many at that time who saw it as being a danger to morality.

At Clebsch's suggestion Wiener constructed plaster of Paris models of mathematical surfaces which were exhibited in London, Munich and Chicago.

Körber describes Wiener in [1]:-

As a final comment on Wiener, let us mention that there is a manoeuvre in the game of Mornington Crescent called the "Wiener" manoeuvre. For those who have not heard of this game it is strategy game played by two or more players, or sometimes by teams. The manoeuvre was named after Wiener by Minski who read his bookAn able and respected teacher, Wiener trained a great number of students while conducting important research. ...[He]was liked and esteemed for his upright character, his sense of justice, and his kindliness.

*Lehrbuch der darstellenden Geometrie*Ⓣ and applied the patterns described in the text to the game of Mornington Crescent.

**Article by:** *J J O'Connor* and *E F Robertson*

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