Compound Microscope, by Arthur Chevalier, Paris, c. 1859-1874

The body of this copper alloy instrument is supported on a rack and pinion, mounted on the cylindrical limb. A draw tube extends from the top of the body and the lower end has an internal thread for the objective. A milled-headed screw at the top of the limb operates the fine focus. The mechanical stage is circular and has two spring clips for specimens. A square sectioned bar below the stage holds a rotating disk with four apertures, which can racked up and down on the bar. A plano-concave mirror is mounted on an articulated arm at the end of the bar. The instrument is carried on trunnions on a heavy, weighted horseshoe base.