Astronomical Instruments of the Imperial Observatory

A full-page engraving depicts three different types of mathematical or drafting instruments, specifically compasses and dividers, set against a minimalist landscape background. At the top is a large pair of wing compasses with a curved adjustment arc featuring a screw mechanism for fine adjustment; the legs are tapered and the head is rounded. At the bottom left is a pair of proportional or reduction compasses, featuring a central pivot and four points, allowing for scaling measurements; the tips are decoratively engraved. At the bottom right is a large sector or folding rule, shown partially open, consisting of two flat legs joined by a circular hinge with various scales and graduations engraved along the length of the arms.