The second apparatus used by Gustav Kirchhoff and Robert Bunsen in 1860/61 when they established the foundations of scientific spectroscopy was a 4-prism spectroscope built by Carl August Steinheil at Munich based on instructions by Kirchhoff. The prototype built for Kirchhoff and Bunsen is preserved at Potsdam. A copy from the following series built by Steinheil is at Deutsches Museum in Munich, see https://digital.deutsches-museum.de/projekte/gruendungssammlung/detail/1972/ . Are there more of these instruments by Steinheil in museums and collections? These instruments were rather expensive and should be rare. The backgound of this question is a restoration project of the Potsdam prototype.