Compound microscope

The cylindrical tube has a top extension that slides inside the tube under friction. It also has a scale marked 160–180–200 and houses the eyepiece. At the very bottom is a revolver with a double hoop that holds lenses that can be easily interchanged. On the sides of the tube are 2 screws that move it vertically using a rack mechanism for coarse focusing. Fine focusing is achieved with a screw marked 0 to 60 at the top of the pillar. The quadrangular stage is held at the bottom of the pillar. It has a central hole and 2 other holes for slide clips or magnifying glasses. Under the stage is the iris-style diaphragm used to control how much light passes through. The plano-concave mirror is attached to the back pillar in a way that allows it to move in all directions. The microscope sits on a quadrangular pedestal with an articulated screw that enables the whole instrument to tilt until it is horizontal. A side screw controls the tilt and holds the instrument in place. The base is a heavy horseshoe shape designed to provide good support. On the heel is the manufacturer's inscription: "R&J. Beck. Ltd. London. 23479."