The sphere displays several noteworthy characteristics. The base, which is very heavy, terminates in lions' paws. It is made of blackened, turned and moulded bronze. The base supports the brass horizon, which bears the names of the winds in Italian, and the division into four quadrants of 0? to 90? each.
The polar caps, the equator and the tropics are divided into degrees. The band of the zodiac bears the names of the signs in Latin, accompanied by the symbols of the signs themselves.
From the band departs a horizontal ring, fixed to the graduated meridian circles. The ring, or armilla, is 65 mm wide, and bears markings relating to the extent of each sign of the zodiac, the names of the signs and the symbolic figures which represent them, in addition to the days of the month and the names of the months.
Fixed to this horizontal band are two diametrically opposed bars, each of which ends with a moulded sight, pierced in its lower portion. The sights are tangents to a circle which project beyond the band itself, which is graduated and fixed to the internal circumference of the band. The lower face of the band bears a series of Roman numerals in columns, radiating towards the centre.
At the centre of the armillary sphere is a crystal sphere, pierced by the inclined axis. The significance of the crystal sphere has been the subject of much discussion.
Under the horizon circle is the signature 'HIERONIMUS. VVLPARIAE. FLORENTINUS. FA. A. D. M. D. LX. IIII.'.
See M. Miniati, Museo di Storia della scienza:. Catalago (Florence, 1991).