This nocturnal consists of three overlapping disks of different diameters: the largest shows the zodiacal calendar; the middle one carries the hours and the index; the smallest—a toothed disk—has a long index arm and the inscription "Horologium nocturnum." On the back are engraved two altitude quadrants, hour lines for the sundial, a shadow square and, in the center a "Tabula Solis motus" (Table of the motion of the Sun) indicating the Sun's entrance into the zodiac signs. Signed by Girolamo della Volpaia and set for latitude 43°30' (Florence). Similar to items inv. 1286 and 3811. Provenance: Medici collections.