Compound Microscope, by Andrew Pritchard, London, c. 1835

This copper alloy instrument stands on a cylindrical pillar on a flat tripod foot. An inner pillar telescopes upward and is held in place by a tightening collar. The cylindrical limb is carried on a compass joint. A rack and pinion extends a bar, with a triangular cross section, from within the limb that carries the body tube on an arm. The eyepiece pushes into the top of the body and a spring-mounted nose has an internal thread to take an objective. None are present. A screw collar around the lower end of the body can extend and retract the nose for fine focusing. The mechanical stage has a rectangular stage plate with a bracket on two pegs to hold slides. A circular spring stage attaches to the stage hole by a bayonet fitting. A sliding sleeve carries the concave mirror in a horseshoe mount on the lower end of the limb. A plaster disk is on the reverse of the mirror.