Focusing is typical Cuff-style. It consists of a sliding vertical pillar (C; rectangular in cross-section) supported by the main support shaft (D; mounted to the case), a thumbscrew, and a base (B) that can be secured to the support shaft with a clamping screw (A). The main pillar (D) is calibrated (1–6) for the working distance of each of the six objectives. In order to set focus, the operator would first loosen the clamping screw (A), then slide the microscope support arm (E) plus focusing mechanism to the position corresponding to the objective being used. The correct position is when the top of the arm matches the appropriate (objective) number. Then the clamping screw would be tightened, fixing the lower screw base (B) to the main pillar (D). Up or down movement of the microscope body would then be achieved by turning the thumbscrew, changing the distance (arrow) between the clamping screw base and microscope body support arm. Thus, coarse focus would have been done "by hand" (moving the entire mechanism along the support shaft), and fine focus via the Hevelius screw mechanism.