This elegant quadrant features an unusual scalloped rim. On the front, the letters "A.D." are engraved at the center of the band. The rim carries three graduated scales: the degree scale, identified by the letter G, and other two scales divided into 48 equal parts and 48 decreasing parts respectively, identified by the letters A and L. The middle of the plate is engraved with a zodiacal calendar, a small index pivoting at its center. The back displays the declinations of many stars, some hour markings, and a motto on the brevity of life signed "T.R." Provenance: Medici collections.