This Drum Microscope (Oberhaeuser #1956) has a lead-filled base with a substage cutout to reveal the planoconcave illumination mirror. A spring-loaded focusing mechanism is contained within the support shaft and is actuated by a knurled knob beneith the shaft. The optics consist of three eyepieces, two nosepieces, and two objective lenses. The low magnification lens is a single plano-convex lens. The other nosepiece has an objective of three stacked lenses. There is a Bull's Eye lens (planoconvex) for illuminating opaque samples. The microscope body tube has no field lens, however it telescopes to allow for different focal length objective lenses and the three eyepieces. Specimens are held onto the stage with spring clips. This microscope comes with several, labeled glass slides and a mahogany storage case. The case also is stamped with the serial number "1956". This serial number dates the manufacture of the instrument precisely to 1849/50*. Imaging is good with a maximum magnification of approximately 125x. The microscope is 23cm tall.

The drum microscope represents an evolution from the "Pocket Microscope" of Benjamin Martin (1704-1782), with improvements in the focusing mechanism, substage mirror, and optics. This microscope is identical to microscope No. 28 in the collection of the Royal Microscopical Society.