Monocular microscope "Sentry Box"

This type of microscope is commonly known as a "sentry box" and has a design similar to a Benjamin Martin pocket microscope. These used to be made for middle-class enthusiasts as they cost less to produce and were more accessible to amateurs than conventional microscopes, helping to popularize science among society.

It is structured around a cuboid wooden box. Inside are 2 tubes, one inside the other, and both surrounded by wooden rings. The outer tube is fixed in place and decorated with embossed green leather, while the sliding inner tube is decorated with yellow paper, and has the eyepiece and lens at the ends. To focus, the inner tube slides vertically inside the outer tube. Both lenses are fixed in place, surrounded by protective wooden rings, and have wooden covers. Inside the box is a flat mirror surrounded by a wooden ring. There are 2 openings at the sides of the box to hold the item being examined.