This is a compound microscope made by Edmund Hartnack (1826–1891) of Paris. It consists of an all-brass stand with a heavy horseshoe base with leather bottom, a swinging mirror assembly, and a single support pillar for focusing and support of the microscope body. The body is screwed into a brass bar limb that moves with the focus mechanism. Focus is by a fine screw thread actuated by a large top knob. The microscope optics consist of a Huygenian eyepiece (eye and field lens) and two objectives screwed into a rotating nosepiece. The robust stage has two slide clips on top and a dovetail assembly underneath. Originally this stage slider supported a cylindrical diaphragm, but it is now missing. Engraved on the microscope body is "E. Hartnack, Sucr. de. G. Oberhaeuser, Place Dauphine 21, Paris". On the focus knob stem is the stamped number "25". Imaging is very good yielding a resolution of <1µm with only slight chromatic aberration visible at high magnification. The total height of the microscope is 29.5cm.
Edmund Hartnack, the nephew of Georges Oberhaeuser, joined him in his shop at Place Dauphine in 1857 forming the firm Oberhaeuser and Hartnack. In 1860 Hartnack took over the firm and continued to make instruments. In 1870 the Hartnack moved the firm to Potsdam where he became partners with Adam Prazmowski creating the firm Hartnack and Prazmowski (of both Paris and Potsdam). After changing hands a few more times, the firm was purchased by Nachet of Paris in 1898.
The Golub Collection has a Drum Microscope from the Oberhaeuser firm at Place Dauphine, Paris.
