Dividing engine used to engrave the graduated circles of astronomical instruments. The machine basically consists of a revolving circular platform 160 mm in diameter. Its toothed edge meshes with an endless screw, which is turned by a handle with a graduated drum. Every turn of the endless screw rotates the platform by 10'. Since the graduated drum, which is integral with the endless screw, is divided into 300 parts, a turn of the screw by an angle equal to one division of the drum translates into a 2" turn of the platform. The operator attached the circle to be divided on the platform, making sure that the circle was concentric with the platform. The operator engraved one line for every fraction of a turn of the endless screw moving the platform. The engraving was done with a burin on the outer surface of the circle—which was usually silvered—or on the edge. The burin was integral with the engine stand. This machine was made at the workshop of the Museo di Fisica e Storia Naturale of Florence at the behest of Giovanni Battista Amici.