Theodolite built by Erasmus Habermel. The central disk carries four linear scales and the shadow square. At the center pivots a diopter with an index and a magnetic compass. Attached to the rim are a circular band with six concentric circumferences, a degree scale, and two diametrically opposing viewers. The instrument was used to measure heights and distances and to record position angles in surveying. There is a gold-tooled leather case. Brought to Florence from Germany by Prince Mattias de' Medici in the first half of the seventeenth century.