CARTOGRAPHY

the art and science of graphically representing a geographical area, usually on a flat surface such as a map or chart; it may involve the superimposition of political, cultural, or other nongeographical divisions onto the representation of a geographical area. Cartography is an ancient discipline that dates from the prehistoric depiction of hunting and fishing territories. The Babylonians mapped the world in a flattened, disk-shaped form, but Ptolemy established the basis for subsequent efforts in the 2nd century AD with an eight-volume work on geography that showed a spherical Earth. Maps produced during the Middle Ages followed Ptolemy's guide, but they used Jerusalem as the central feature and placed East at the top. These representations are often called T-maps because they show only three continents (Europe, Asia, and Africa), separated by the T formed by the Mediterranean Sea and the Nile River. More accurate geographical representation began in the 14th century when portolan (seamen's) charts were compiled for navigation. The discovery of the New World led to the need for new techniques in cartography, particularly for the systematic representation on a flat surface of the features of a curved surface (see projection; Mercator projection). The 17th and 18th centuries saw a vast outpouring of printed maps of ever-increasing accuracy and sophistication. Noteworthy among the scientific methods introduced later was the use of the telescope for determining the length of a degree of longitude. Modern cartography largely involves the use of aerial photographs as a base for any desired map or chart; the procedures for translating photographic data into maps are governed by the principles of photogrammetry (q.v.) and yield a degree of accuracy previously unattainable. Satellite photography has made possible the mapping of features of the Moon and of several planets and their satellites.