Biconvex objective lens mounted in a cardboard ring. The aperture of the lens is 40 mm, the focal length 1,480 mm, the diameter of the ring 54 mm. The glass, which has a red tint, contains elliptical bubbles and some inclusions. The lens is scratched. One side of the ring has an inscription ("V. Torr: 8.feb.1643") indicating the maker (E. Torricelli) and the construction date. On the other side can be read "B. 2 1/2," i.e., 2.5 braccia (1,460 mm, a measure of the focal length).