This nocturnal consists of three overlapping disks of different diameters: the largest shows the zodiacal calendar; the middle one carries the hours and the rotating index; the smallest—a toothed disk—has a long index arm and the inscription "Horologium nocturnum." On the back are the signature of Girolamo della Volpaia and the date (1567), the solar quadrant, and the disk for determining the Sun's position in the zodiac signs. The instrument is set for latitude 43°44' (Florence). Similar to items inv. 2503 and inv. 1286.