This unusual theodolite is joined to the book describing its construction and use. Placed at the horizontal on a pedestal, the book carries on its cover a magnetic compass with a sundial, and on its top edge a viewer, with a degree scale, a shadow square, and a plumb bob. The book was written in German and printed in Nuremberg in 1625. It explains that the purpose of the instrument was to measure distances, heights, and depths, to conduct surveying work, and to produce perspective drawings. The maker was Michael Bumel; the author of the book, and possible inventor of the instrument, was Andreas Albrecht, from Nuremberg. Provenance: Medici collections.