Reflecting telescope of the Newtonian type with an octagonal wooden tube blackened internally. Made by Leto Guidi, it closely resembles the telescope illustrated by Jean-Antoine Nollet in Leçons de physique expérimentale (Paris 1743-1748). The instrument is fixed by means of a brass horizontal shaft to an artistically designed three-legged wooden table with a revolving surface. As the telescope can be tilted at different angles to the horizontal, the arrangement effectively constitutes an altazimuth mount. The mirror has a diameter of 170 mm and a focal length of 1,960 mm. There is a finder with cross-wires. A telescope made by Leto Guidi in 1766 was also preserved at the Ximenian Observatory in Florence, as shown by an inventory of 1786, compiled the day after the death of Leonardo Ximenes.