An unusual adjustable condenser lens on lacquered brass stand, that can be used for magnifying close work, such as tying fishing flies, philately, or entomology, where it can be used for quick identification before microscopic examination. Originally used for optical bench work or to focus light in scientific experiments during the late 19th or early 20th century. Features include adjustable height and rotation of the lens, as well as adjustment for the diaphragm to restrict the amount of light reaching the lens. Circa 1900.
