The dissemination of the magnetic compass in the late Middle Ages and the demand for increasingly precise maps in the Renaissance drove the development of surveying instruments. Documents as early as the fifteenth century show the use of protractors fitted with magnetic needles for land surveying. These instruments were generally derived from the back of the astrolabe; in the following century, they were called polymeters, surveying magnetic compasses, theodolites, holometers, and graphometers. To this category, we can add the surveyor's square, which was more specifically designed, however, for plotting orthogonal alignments.
In the military sphere, the magnetic compass was also applied in the second half of the sixteenth century to a variety of instruments such as the radio latino, the archimetro, and the altazimuth square. A very popular instrument among seventeenth- and eighteenth-century surveyors was the plane table, which enabled them to simultaneously measure and draw the map of an area.
Last update 28/feb/2008