Author: Jochen Hennig

Title: "The prism and the telescopes are manufactured by Steinheil in Munich" - A replication of the early spectroscopical experiments of Gustav Kirchhoff and Robert Bunsen

Abstract: This study focuses on the spectroscopical experiments performed by the physicist Gustav Kirchhoff (1824-1887) together with the chemist Robert Bunsen (1811-1899) in Heidelberg in 1859. Due to the far-reaching results concerning both the establishment of chemical spectral analysis as well as the interpretation of the Fraunhofer lines these experiments became widespread in physical, chemical and later on in historical literature.

The knowledge about the first spectral apparatus constructed by Kirchhoff and Bunsen themselves was hitherto limited to descriptions given by Kirchhoff and Bunsen in their paper "Chemical analysis by spectrum-observations" in 1860.

Here a letter written by Kirchhoff will be presented, that includes more details concerning the optical components used for this spectral apparatus. On the basis of these sources a replica of the apparatus could be constructed close to the original. I will present the replica and discuss my experiences gained in the work with this apparatus when I replicated the early flame-spectroscopical experiments of Kirchhoff and Bunsen. I will argue, that Kirchhoff and Bunsen could fall back onto their background and various practical experiences they already had possessed at the beginning of their spectroscopical experiments.

From the letter written by Kirchhoff it also follows, that Kirchhoff and Bunsen used optical components manufactured by Carl August Steinheil for their first spectral apparatus. Also the next steps of the collaboration between the instrument-maker Steinheil from Munich and the scientists Kirchhoff and Bunsen living in Heidelberg will be discussed by the use of further sources that have not received attention yet. I will show how Kirchhoff and Bunsen brought their experiences to bear in the construction of two spectral apparatus that were made in the optical workshop of Steinheil. Since both these apparatus, one for the purpose of chemical analyses, the other one to investigate the solar spectrum, became widespread and were copied by various instrument makers, the initial development of spectroscopes was already shaped in 1859 by the collaboration of Bunsen, Kirchhoff and Steinheil.