Friedrich Körner (mechanic)

Johann Christian Friedrich Körner (born August 2, 1778 in Weimar ; † February 2, 1847 in Jena ) was a German mechanic, manufacturer of optical glass and optical instruments. Coming from Weimar, he was trained as a craftsman in Freiburg and studied mathematics in Jena. In 1816 he became a university mechanic in Jena. He was a "grand-hearted court mechanic" and held lectures as a private lecturer on the manufacture and handling of instruments. His best-known apprentice was Carl Zeiss .

The Jenenser astronomer Karl Dietrich von Münchow wanted to create a telescope for the observatory based on calculations. However, the flint glass available was of poor quality. Flint glass is required in combination with crown glass in order to be able to manufacture achromatic objectives and eyepieces . Therefore, with the support of Grand Duke Carl August, a small glassworks was founded in 1817 , which was also supported by Johann Wolfgang von Goethe . This initially had little success. In 1822, Goethe was visited by Georg Friedrich von Reichenbach , next to Joseph von Utzschneider one of the managing directors of the Munich Optical Institute, in which suitable glass was produced and in which Joseph von Fraunhofer also worked. During this visit, Goethe succeeded in eliciting some production secrets from Reichenbach that helped grain further. In 1827 Körner wrote: “I am very satisfied with the quality and effect of my manufactured flint glass. The mass obtained by two fusions is 7 quintals. ... I have constructed achromatic objectives with my flint glass which have withstood comparison with very good English ones to their advantage. "

Further melting tests were also carried out for crown glass in order to make itself independent of other suppliers of optical glasses. The new Grand Duke Carl Friedrich also supported the experiments financially. Goethe succeeded time and again in convincing Grand Duchess Maria Pavlovna of financial injections. The chemist Johann Wolfgang Döbereiner wanted to help with technical advice, but it turned out to be of little use.

Körner's gravestone at the Johannisfriedhof in Jena

In the end, crown and flint glass were sufficiently produced that it could also be sold. In 1847, for example, Carl Kellner , who built optical equipment in Wetzlar , asked his friend Moritz Hensoldt to buy glasses from Körner on the way from Hamburg to his native Sonneberg (southern Thuringia).

In addition to some other optical devices, Körner also produced so-called simple microscopes , i.e. those that only consist of one lens or double lens and function similar to a magnifying glass . These microscopes were described and praised in more detail by Matthias Jacob Schleiden in 1845, especially as dissecting microscopes . He describes that magnifications of 15 to 120 times could be achieved with various double lenses. Hugo von Mohl, on the other hand, found the stronger double lenses only "very mediocre" in 1846.

With the death of Körner the operation of the glassworks was stopped.

Individual evidence

1. ↑ ^{a b c d e f} Dieter Gerlach: History of microscopy . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1781-9 , pp. 265-268 .
2. ↑ Catalog of the German National Library ( entry )