Objective: 1647 / Tube: second half 18th cent. (?)
length 1115 mm
Telescope with a single brass tube, made from two tubes soldered together. There is a wooden diaphragm about halfway along the tube. The biconvex objective by Evangelista Torricelli is inserted in a cardboard ring bearing the inscription "V. Torr. in Fior. 1647. Br 1 3/4," i.e., a focal length of 1.75 braccia [1,022 mm]. The eyepiece is plano-convex, with a focal length of 32 mm. The glass quality of the two lenses is very different: the objective, typical of the first half of the seventeenth century, has a slight yellow tint and contains many small bubbles and inclusions; the eyepiece glass, certainly of later date, is clear and homogeneous. The instrument's magnification is 32. First mentioned in the 1776 inventory of the Museo di Fisica e Storia Naturale, it was probably made in the second half of the eighteenth century to house the Torricelli objective.