This small astrolabe comprises two tympanums for latitudes 37° (Seville) and 40° (Toledo). The limb of the mater is graduated into four 90° parts. The back carries the orthographic projection of Juan de Rojas. The lower left quadrant is occupied by the shadow square. The rule is engraved with the words "Horizon Universalis" [universal horizon] and is graduated correspondingly on the back, while the edge of the mater gives the concordance between the zodiac signs and the calendar months. Provenance: Medici collections.