Zubler's book is another instance of the early-modern fashion for writing on somewhat exotic surveying instruments and emphasising military problems among their universal applications. Zubler's design is a further example of a triangulation instrument and its relevance to range-finding and to surveying fortifications is probably even more prominent that was usual in such books.
Zubler's triangulation instrument (see figure 71) dispenses with the third arm of the Bürgi design (figures 68 and 70), but can be used in the same way by fixing the angle between the baseline and the pivoted arm, setting the sliding sight on the baseline arm to the scaled length of the baseline itself and finally, from the second station, sighting across the two arms while moving the second sliding sight into alignment with the first sight and the target. The position of this second sight, adjusted to scale, then gives the side of the triangle on the ground. The provision of a degree scale on a semicircular plate at the pivot permits other techniques involving angle measurement or setting the arms at right angles.