October 12: Carl August von Steinheil

Carl August von Steinheil

October 12, 1801 – September 14, 1870

Carl August von Steinheil was a German physicist.

Steinheil was born in Ribeauvillé, Alsace. He studied law in Erlangen then astronomy in Göttingen and Königsberg. He continued his studies in astronomy and physics when he started living on his father's manor in Perlachseck near Munich. He was professor for mathematics and physics at the University of Munich from 1832 to 1849.

In 1839, Steinheil used silver chloride and a cardboard camera to make pictures in negative from the Museum of Art and the Munich Frauenkirche, then taking another picture of the negative to get a positive, the actual black and white reproduction of a view on the object. The round pictures were about four cm wide, the way to get these pictures was called Steinheil method.

In 1846 Steinheil was called to Naples to install a new system for weight and measure units. Three years later, he was in the Board of Telegraphy in the Austrian Trade Ministry, designing a telegraph network for the entire empire, and helped to form the "Deutsch-Österreichischer Telegraphenverein" (German-Austrian Telegraph Society). In 1851 he started the Swiss telegraph network, when he returned to Munich as 'Konservator' of the mathematic-physical collections and ministerial secretary in the Trade Ministry of Bavaria.

He founded the optical-astronomical company C.A. Steinheil und Söhne to build telescopes, spectroscopes and photometers (his invention, used to measure brightness). In 1852 he added refractors and reflectors with silver-covered mirrors to the production. The silvering was done in a process developed by his friend Justus Liebig. Since 1862, his sons continued his company.

The Lunar crater Steinheil is named in his honor.