In 1860, Edmund Hartnack (1826-91) formed a partnership with George Oberhauser (1798-1868) in a microscope-making firm, already in business in 1830. Hartnack became sole owner in 1860, and on his departure for Potsdam in 1870 he turned the company over to Adam Prazmowski (1821-?), who had worked at the Warsaw observatory. The firm later changed its name to Bézu & Hausser, and was eventually taken over by Nachet toward the end of the 19th C.