Microscope No. 109 comes with two lenses.

This brass lens screws into the microscope body. It consists of a single low-magnification bi-convex lens (dia=8mm, f=2.0cm, aperture=3mm). The lens is held in place by a brass retaining ring.

This second lens, #5, consists of a turned ivory body 2.8cm in diameter, and a plano-convex lens (dia=6mm, f=3mm, aperture 2mm). The lens is held in place with a threaded ivory ring. It is unlikely that this lens was part of the original microscope system, as the outer threads do not match the microscope body.