Compound Microscope in Case, by Andrew Pritchard, London, c. 1830

Compound microscope in case, by Andrew Pritchard, London, c. 1830. This copper alloy instrument (50705.1) is carried on a cylindrical pillar that stands on a flat tripod base. A post telescopes from the top of the pillar and the limb is held by collar on a compass joint on top of the post. A rack and pinion mechanism, operated by a mill-edged knob, raises a bar, with a triangular cross section, from within the limb. This carries the monocular body tube on an arm. The eyepiece pushes into the top of the body and the nose has an external thread to take objectives. Two pins on the underside of the stage push into a bracket on the limb. There are two dovetail grooves on the stage plate and the stage hole has a thread that takes a condenser in a copper alloy tube with a sliding adjuster. A substage lens is mounted on a sliding sleeve on the limb and a concave mirror is mounted below it. There is also an objective in a can that does not fit this instrument (50705.2). The box is mahogany (50705.3) and has a hinged lid with a lock.