Drum Microscope with Accessories, by Georges Oberhauser, Paris, c. 1840

The instrument stands on a circular, weighted base. The circular stage has two spring clips and is mounted on a housing with a window that allows light to the Plano-concave mirror within. The body tube, with an objective screwed in place, pushes into a split sleeve supported by a pillar on the edge of the stage. It slides in the sleeve for coarse focusing and a mill headed screw on the base of the pillar adjusts the fine focus. A green leather covered box contains three objectives that screw onto the conical nose. The eyepiece pushes into the top of the body. An alternative horizontal tube with a camera lucida may be used in place of the eyepiece. The mahogany case also contains a stand with a bull's-eye condensing lens and a box of accessories. The mahogany case has wooden supports to hold the instrument and accessories, and has a removable pad which sits in the lid. The base of the bull's eye lens stand is shaped to fit against the microscope. It can also hold a stage with an aperture disc. The accessories in the smaller box are two needles on wooden handles, copper alloy forceps, four glass discs, and nine slides.