The coarse focus screw is on the right side of the limb; the fine focus is by a vertical high precision screw, both the screws move the gearset of the stage. The stage dovetails into the bracket, has mechanical movements on the horizontal plane ond on the top has a blackened glass surface, with fitting for two brass clips (one is missing). Below it, a condenser with lens and a disc with four rotating holes in a bayonet fitting provides the desired illumination. An alternative plane stage in blackened brass is present: on it can be mounted a brass circular disc with two fixed clips for small size slides and on its top there is a circular housing for a Buonanni-type spring. The horizontal body tube has rack and pinion adjustment to the graduated eyepiece extension tube, engraved with a scale 0-80 mm. The objective is mounted on a right-angle component containing a prism and is attached via a bayonet fitting to the body tube. The mounting permits the body tube to be swivelled through to 90° on top of the short brass bracket; we suppose it had other accessories for different observations (see "Des Microscopes et de leur usage", C. Chevalier, 1839, first edition, plate 4). The instrument can be set in the vertical position; an objective collar is used in this configuration. All the parts of the microscope and all of the accessories are engraved. The assembly number assigned to the instrument is 4.