Plano-concave eyepiece lens, with cracked glass, mounted in a wooden ring covered with paper. The lens diameter is 30 mm, the aperture 24 mm, the focal length -200 mm (the negative focal length means that the lens is diverging). On the ring can be read "B: 10," indicating that it was to be combined with an objective of 10 braccia (5,840 mm). Intended for very powerful instruments, this type of eyepiece was used in the years between 1640 and 1660. The lens is of Florentine origin, as can be deduced from the reference to braccia. Moreover, the ring and the inscription, which resemble those of items inv. 2572 and inv. 2571, suggest an attribution to Evangelista Torricelli or another Florentine optician such as Ippolito Francini or Jacopo Mariani.